Event: 1502: Histone deacetylase inhibition

Short Name: Histone deacetylase inhibition

AOPs Including This Key Event

Stressors

Biological Context

Event: 1503: Histone acetylation, increase

Short Name: Histone acetylation, increase

AOPs Including This Key Event

Biological Context

MAA induces acetylation of histones H3 and H4 in Sprague-Dawley (Rattus norvegicus) [Wade MG]. It is also reporeted that MAA promotes acetylation of H4 in HeLa cells (Homo sapiens) and spleens from C57BL/6 mice (Mus musculus) treated with MAA [Jansen]. VPA induces hyperacetylation of histone H4 in protein extract of mouse embryos (Mus musculus) exposed in utero for 1h to VPA [Di Renzo]. Apicidin, MS-275 and sodium butyrate induce hyperacetylation of histone H4 in homogenates from mouse embryos (Mus musculus) after the treatments [Di Renzo]. MAA acetylates histones H3K9 and H4K12 in limbs of CD1 mice (Mus musculus) [Dayan C].

Event: 1504: p21 expression, increase

Short Name: p21 expression, increase

AOPs Including This Key Event

Biological Context

FK228 up-regulated p21 level in human esophageal cancer TE2 cells (Homo sapiens) [Hoshino I]. MAA induced p21 up-regulation in human prostate cancer cell lines (Homo sapiens) [Parajuli]. MAA increases p21 expression in human bladder carcinoma cells, T24 (Homo sapiens) [Glaser]. MAA up-regulated p21 expression in limbs of CD1 embryonic mice (Mus musculus) [Dayan C].

Event: 1505: cell cycle disorder

Short Name: cell cycle disorder

AOPs Including This Key Event

Biological Context

MAA blocks G₁/S transition in human prostate cancer cell cycles (Homo sapiens) [Parajuli]. The change in the amounts of cells in G₁ phase and S phase of cell cycle was detected in mouse HDAC1^-/- fibroblast lines (Mus musculus) [Zupkovitz].

Event: 1262: Apoptosis

Short Name: Apoptosis

AOPs Including This Key Event

Biological Context

The apoptosis and proliferation inhibition induced by MAA was measured in human prostate cancer cell lines (Homo sapiens) [Parajuli]. The cell viability inhibition induced by SAHA or TSA was observed in NHDFs (Homo sapiens) [Glaser]. The proliferation of the HDAC^-/- ES cells was inhibited compared to HDAC^+/+ ES cells (Homo sapiens) [Zupkovitz].

Event: 1506: spermatocyte depletion, testis atrophy/weight loss (testicular toxicity)

Short Name: testicular toxicity

AOPs Including This Key Event

Biological Context

It has been reported that mice lacking both Ink4c and Ink4d produced few mature sperm, and the residual spermatozoa had reduced motility and decreased viability (Mus musculus) [Zindy]. The sperm counts in the cauda epidydimis of rats exposed to butylparaben were significantly decreased (Rattus norvegicus) [Oishi S2001]. EGME or MAA treatment induced the testicular damage in rat (Rattus norvegicus) [Foster PMD1983]. EGME were shown to deplete the spermatocytes in CD-1 mice (Mus musculus) and CD rats (Rattus norvegicus), principally pachytene cells, but with other stages affected with increasing dose [Anderson D]. The testicular lesions induced by 2-methoxyethanol were observed in rats (Rattus norvegicus) and guinea pigs (Cavia porcellus), which are different in onset, characteristics and severity [Ku WW]. EGME has effects in disruption of spermatogenesis in rabbits (Oryctolagus cuniculus) [Foote]. Dimethoxyhexane (DMH) induces testicular toxicity such as spermatocyte death in seminiferous tubule stages I-IV and stages XII-XIV and MAA increase in urine in Sprague-Dawley rats (Rattus norvegicus) MAA treatment induces spermatocyte death in Sprague-Dawley rats (Rattus norvegicus) [Wade 2008]. Treatment of TSA resulted in a dose-dependent decrease in relative testis weight due to impaired spermatogenesis in mice, and impaired meiosis [Fenic 2004, 2008].

Relationship: 1709: Histone deacetylase inhibition leads to Histone acetylation, increase

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

Hyperacetylation by HDIs such as SAHA and Cpd-60 are observed in mouse (Schroeder et al). TSA induces acetylation of histone H4 in time-dependent manner in mouse cell lines (Alberts et al). AR-42, a novel HDI, induces hyperacetylation in human pancreatic cancer cells (Henderson et al.). SAHA and MS-275 hyperacetylates lysine of histones in human cell lines of epithelial (A549) and lymphoid origin (Jurkat) (Choudhary et al.). HDAC inhibitors, phenylbutyrate (PB) (2 mM) and TSA (200 nM) acetylate histones H3 and H4 in synovial cells from rats with adjuvant arthritis (Chung et al 2003). SAHA treatment induces the H3 and H4 histone acetylation in human corneal fibroblasts and conjunctiva from rabbits after glaucoma filtration surgery (Sharma A 2016). TSA induces the acetylation of histones H3 and H4 in Brassica napus microspore cultures (Li H et al 2014).

The inhibition of HDAC by HDIs is well conserved between species from lower organism to mammals [Richon VM 2004, Steffan JS et al, Desjardins D et al, Ansari J et al, Miyanaga A et al, Mishra N et al, Hockly E et al.] HDIs reduced lethality in Drosophila model and the HDAC activity was inhibited with HDIs in rat PC12 cells [Steffan JS]. HDIs inhibited restores the rate of resorption of subretinal blebs in hyper glycemia in brown Norway rat and HDAC activity was inhibited with HDIs in human ARPE19 cells [Desjardins D et al]. HDIs were approved as drugs for multiple myeloma and T-cell lymphoma by FDA [Ansari]. HDIs inhibited cell growth in human non-small cell lung cancer cell lines [Miyanaga]. HDAC acetylation level was increased by HDIs in MRL-lpr/lpr murine model of lupus splenocytes [Mishra]. SAHA increased histone acetylation in brain and spleen of mice [Hockly]. MAA inhibits HDAC activity in HeLa cells and spleens from C57BL/6 mice [Jansen MS 2004]. It is also reported that MAA inhibits HDAC activity in testis cytosolic and nuclear extract of juvenile rats (27 days old) [Wade MG 2008]. VPA and TSA inhibit HDAC enzymatic activity in mouse embryo and human HeLa cell nuclear extract [Di Renzo].

Key Event Relationship Description

The gene transcription is regulated with the balance of acetylation. The histone acetylation leads to the gene transcription increase, whereas the deacetylation leads to the gene silencing in general. The HDAC inhibitors (HDIs) inhibit deacetylation of the histone, leading to the increase in histone acetylation and gene transcription. HDACs deacetylate acetylated histone in epigenetic regulation (Falkenberg 2014). HDAC inhibition by HDIs leads to hyperacetylation of histone and a large number of cellular proteins (Falkenberg 2014). Histone hyperacetylation by HDIs leads to transcriptional activation of genes (Falkenberg 2014). Measured properties of 20 valproic acid derivatives show that concentration of half-maximum inhibitory effect (IC₅₀) in the HDAC enzyme inhibition correlates with teratogenic potential, and HDAC inhibitory derivatives show hyperacetylation of core histone 4 in treated F9 cells (Eikel 2006).

Evidence Supporting this KER

HDACs are important proteins in epigenetic regulation of gene transcription. Upon the inhibition of HDAC by HDIs, the acetylation of lysine in histone remains and it leads to transcriptional activation or repression, changes in DNA replication and DNA damage repair. It is likely that the post-translational modifications such as acetylation, phosphorylation and methylation regulates biological function, which suggests that the hyperacetylation induced by HDAC inhibition by HDIs leads to the regulation of gene transcription.

HDIs increase histone acetylation in brain (Schroeder FA). The HDI selectivity exists, in which SAHA is a more potent inducer of histone acetylation than MS-275, and more acetylation sites on the histones H3 and H4 are responsible to SAHA than MS-275 (Choudhary 2009). HDI AR-42 induces acetylation of histone H3 in dose-response manner in human pancreatic cancer cell lines (Henderson 2016). HDAC1 and HDAC3 activity are inhibited by m-carboxycinnamic acid bishydroxamide (CBHA) and suberoylanilide hydroxamic acid (SAHA) [Richon VM et al]. SAHA, inhibiting HDACs, leads to cause growth arrest, differentiation, and/or apoptosis of tumor, and it up-regulates thioredoxin-binding protein-2, whereas it down-regulates thioredoxin [Butler LM et al]. HDAC regulates gene expression of the regulators by deacetylating lysine residues of the transcription factors [Freiman RN and Tjian R]. HDAC activity is related to gene silencing, whereas histone acetyl transferase (HAT) induces histone acetylation leading to gene transcription [Ropero S and Esteller M]. MAA treatment in rats induced histone hyperacetylation in histones H3 and H4 [Wade MG]. MAA-induced spermatocyte death is associated with histone acetylation increase [Wade 2008]. The histone deacetylase (HDAC) inhibition induced by valproic acid (VPA) leads to histone hyperacetylation, followed by teratogenic toxicity [Eikel 2006]. Hyperacetylation of histone H3 in HDAC1-deficient ES cells was associated with proximal p21 promoter, while the distal promoter region was not shown to be associated [Lagger].

HDACs affect a large number of cellular proteins including histones, which reminds us the HDAC inhibition by HDIs hyperacetylates cellular proteins other than histones and exhibit biological effects. It is also noted that HDAC functions as the catalytic subunits of large protein complex, which suggests that the inhibition of HDAC by HDIs affect the function of the large multiprotein complexes of HDAC (Falkenberg 2014).

References

Falkenberg KJ and Johnstone RW. (2014) Histone deacetylases and their inhibitors in cancer, neurological disease and immune disorders. Nat Rev Drug Discov 13:673-691

Eikel D et al. (2006) Teratogenic effects mediated by inhibition of histone deacetylases: evidence from quantitative structure activity relationships of 20 valproic acid derivatives. Chem Res Toxicol 19:272-278

Schroeder FA et al. (2013) A selective HDAC 1/2 inhibitor modulates chromatin and gene expression in brain and alters mouse behavior in two mood-related tests. PLoS One 8:e71323

Choudhary C et al. (2009) Lysine acetylation targets protein complexes and co-regulates major cellular functions. Science 325:834-840

Henderson SE et al. (2016) Suppression of tumor growth and muscle wasting in a transgenic mouse model of pancreatic cancer by the novel histone deacetylase inhibitor AR-42. Neoplasia 18:765-774

Richon VM. et al. (1998) A class of hybrid polar inducers of transformed cell differentiation inhibits histone deacetylases. Proc Natl Acad Sci USA 95:3003-3007.

Butler LM et al. (2002) The histone deacetylase inhibitor SAHA arrests cancer cell growth, up-regulates thioredoxin-binding protein-2, and down-regulates thioredoxin, Proc Natl Acad Sci USA 99:11700-11705

Freiman RN and Tjian R. (2003) Regulating the regulators: lysine modifications make their mark. Cell 112:11-17

Ropero S and Esteller M. (2007) The role of histone deacetylases (HDACs) in human cancer. Mol Oncol 1:19-25

Wade MG et al. (2008) Methoxyacetic acid-induced spermatocyte death is associated with histone hyperacetylation in rats. Biol Reprod 78:822-831

Lagger G et al. (2002) Essential function of histone deacetylase 1 in proliferation control and CDK inhibitor repression. EMBO J 21:2672-2681

Yoshida M et al. (1990) Potent and specific inhibition of mammalian histone deacetylase both in vivo and in vitro trichostatin A. J Biol Chem 265:17174-17179

Gnad F et al. (2011) PHOSIDA 2011: the posttranslational modification database. Nucl Acids Res 39:D253-D260

Alberts AS et al. (1998) Activation of SRF-regulated chromosomal templates by Rho-family GTPases requires a signal that also induces H4 hyperacetylation. Cell 92:475-487

Chung YL et al. (2003) A therapeutic strategy uses histone deacetylase inhibitors to modulate the expression of genes involved in the pathogenesis of rheumatoid arthritis. Mol Ther 8:707-717

Sharma A et al. (2016) Epigenetic modification prevents excessive wound healing and scar formation after glaucoma filtration surgery. Invest Ophthalmol Vis Sci 57:3381-3389

Li H et al. (2014) The histone deacetylase inhibitor trichostatin A promotes totipotentcy in the male gametophyte. Plant Cell 26:195-209

Richon VM et al. (2004) Histone deacetylase inhibitors: assays to assess effectiveness in vitro and in vivo. Methods Enzymol. 376:199-205

Steffan JS et al. (2001) Histone deacetylase inhibitors arrest polyglutamine-dependent neurodegeneration in Drosophila. Nature 413:739-743

Desjardins D et al. (2016) Histone deacetylase inhibition restores retinal pigment epithelium function in hyperglycemia. PLoS ONE 11: e0162596

Ansari J et al. (2016) Epigenetics in non-small cell lung cancer: from basics to therapeutics. Transl Lung Cancer Res 5:155-171

Miyanaga A et al. (2008) Antitumor activity of histone deacetylase inhibitors in non-small cell lung cancer cells: development of a molecular predictive model. Mol Cancer Ther 7:1923-1930

Mishra N et al. (2003) Histone deacetylase inhibitors modulate renal disease in the MRL-lpr/lpr mouse. J Clin Invest 111: 539-552

Hockly E et al. (2003) Suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, ameliorates motor deficits in a mouse model of Huntington’s disease. Proc Nat Acad Sci 100:2041-2046

Jansen MS et al. (2014) Short-chain fatty acids enhance nuclear receptor activity through mitogen-activated protein kinase activation and histone deacetylase inhibition Proc Natl Acad Sci USA 101:7199-7204

Di Renzo F et al. (2007) Boric acid inhibits embryonic histone deacetylases: A suggested mechanism to explain boric acid-related teratogenicity. Toxicol and Appl Pharmacol 220:178-185

Relationship: 1710: Histone acetylation, increase leads to p21 expression, increase

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

TSA and sodium butyrate induced p21 mRNA expression in HT-29 human colon carcinoma cells (Homo sapiens) (Wu JT). Scriptaid, a HDI, up-regulated p21 mRNA expression in mouse embryonic kidney cells (Mus musculus) (Chen S).

Key Event Relationship Description

Upon histone acetylation increase, p21 transcription and protein level are increased. Acetylation of p21 promoter and p21 mRNA level have a close correlation (Gurvich N). Transient histone hyperacetylation was sufficient for the activation of p21 (Wu JT). TSA (0.3 mM) induced p21 mRNA expression in 1 hr, whereas the induction is repressed in 24 hrs after stimulation (Wu JT). On the other hand, butyrate and repetitive doses of TSA induced p21 mRNA expression in 24 hrs (Wu JT). Histone hyperacetylating agents butyrate and TSA induced p21 mRNA expression (Archer SY). HDAC1 overexpression blocked the induction of p21 by butyrate and TSA, indicating that the p21 induction is mediated by histone hyperacetylation (Archer SY). SAHA induced the accumulation of acetylated histones in the chromatin of the p21^WAF1 gene and this increase was associated with an increase in p21^WAF1 expression (Richon VM2000).

Evidence Supporting this KER

HDIs induce histone hyperacetylation and p21 activation leading to the cell cycle arrest, which suggests the close correlation between histone hyperacetylation and p21. In the models proposed for the relationship between histone acetylation and transcription, histone acetylation can be untargeted and occur at both promoter and nonpromoter regions, targeted generally to promoter regions, or targeted to specific promoters by gene-specific activator proteins (Richon2000 et al, Struhl K). Since several results supported a model in which increased histone acetylation is targeted to specific genes and occurs throughout the entire gene, not just the promoter regions, histone acetylation may leads to gene transcription of p21 (Richon2000).

HDIs induce p53-independent expression of p21 via Sp1 binding sites in the p21 promoter (Gartel). MAA up-regulates p21 (cyclin dependent kinase inhibitor 1A; CDKN1A) gene expression in limbs of CD1 mice [Dayan C]. Considering that acetylation of p53 at K379 requires for p53 binding at the p21 promoter region, p53K379 acetylation and induction of p21 expression seemed correlated [Dayan C]. However, MAA did not increased p53, p63 and p73 level in PC-3, although MAA (5 or 20 mM) induces p21 mRNA level in prostate cancer cells including PC-3, which indicates that MAA-mediated p21 enhancement is independent of p53/p63/p73 [Parajuli]. On the other hand, MAA induced histone acetylation of H4 in prostate cancer cells including LNCaP, C4-2B, PC-3 and DU-145 parallel with p21 mRNA level increase, which suggests that MAA-mediated p21 transcription increases are correlated with HDAC inhibition [Parajuli]. HDIs such as SAHA, TSA and MS-275 up-regulates p21 gene expression in T24 bladder carcinoma cells, which also suggests that HDAC inhibition leads to p21 up-regulation [Glaser]. Cyclin-dependent kinase (CDK) inhibitors p21 and p27 are up-regulated in HDAC1-deficient embryonic stem (ES) cells [Lagger]. In HDAC1^-/- mouse embryonic fibroblasts, p21 level increase is observed, which indicates that HDAC suppression leads to p21 up-regulation [Zupkovitz]. Moreover, the increased acetylation of histones H3 and H4 at both proximal and distant promoter regions of p21 was observed in HDAC1^-/- mouse embryonic fibroblasts, suggesting that p21 increase is mediated by the loss of HDAC1 [Zupkovitz]. MAA inhibits HDAC1, HDAC2, and HDAC3 to increase the levels of acetylated histone H4 [Parajuli KR, Jansen MS]. Loss of HDAC1 in ES cells decreased proliferation and cyclin A- and cyclin E-associated kinase activity in the HDAC1 mutant cells [Lagger]. HDIs accumulated acetylation of histones and induced p21 protein and mRNA expression (Richon2000 et al, Wu et al). Hyperacetylation of histone H3 in HDAC1-deficient ES cells was associated with proximal p21 promoter, while the distal promoter region was not shown to be associated [Lagger].

There are several pathways to activate p21 promoter by HDI. A HDI, apicidin, induced p21^WAF1/Cip1 mRNA independent of the de novo protein synthesis and activated the p21^WAF1/Cip1 promoter through Sp1 sites (Han2001). Pretreatment with selective PKC inhibitors calphostin A and rottlerin suppressed the promoter activity of p21WAF1/Cip1 activated by apicidin (Han2001). Furthermore, apicidin-induced translocation of PKCe from cytosolic to particulate fraction was reversed by pretreatment with calphostin C, which suggests the PKCe involvement in apicidin-induced p21^WAF1/Cip1 transcription (Han2001). The p21 promoter activation through Sp1 sites induced by apicidin is thought to be independent of histone hyperacetylation (Han2001). The apicidin is suggested to histone hyperacetylation leading to the antiproliferative activity (Han2000). These results indicate the inconclusive discussion in the linkage between histone acetylation and p21 activation.

References

Gurvich N et al. (2004) Histone deacetylase is a target of valproic acid-mediated cellular differentiation. Cancer Res 64:1079-1086

Wu JT et al. (2001) Transient vs prolonged histone hyper acetylation: effects on colon cancer cell growth, differentiation, and apoptosis. Am J Physiol Gastrointest Liver Physiol 280:G482-G490

Archer SY et al. (1998) p21^WAF1 is required for butyrate-mediated growth inhibition of human colon cancer cells. Proc Natl Acad Sci USA 95:6791-6796

Richon VM et al. (2000) Histone deacetylase inhibitor selectively induces p21^WAF1 expression and gene-associated histone acetylation. Proc Natl Acad Sci 97:10014-10019

Struhl K. (1998) Histone acetylation and transcriptional regulatory mechanisms. Gene Dev 12:599-606

Gartel AL and Tyner AL (2002) The role of the cyclin-dependent kinase inhibitor p21 in apoptosis. Mol Cancer Ther 1: 639-649

Dayan C and Hales BF. (2014) Effects of ethylene glycol monomethyl ether and its metabolite, 2-methoxyacetic acid, on organogenesis stage mouse limbs in vitro. Birth Defects Res (Part B) 101:254-261

Parajuli KR et al. (2014) Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis. Am J Clin Exp Urol 2:300-313

Glaser KB et al. (2003) Gene expression profiling of multiple histone deacetylase (HDAC) inhibitors: defining a common gene set produced by HDAC inhibition in T24 and MDA carcinoma cell lines. Mol Cancer Ther 2:151-163

Lagger G et al. (2002) Essential function of histone deacetylase 1 in proliferation control and CDK inhibitor repression. EMBO J 21:2672-2681

Zupkovitz G et al. (2010) The cyclin-dependent kinase inhibitor p21 is a crucial target for histone deacetylase 1 as a regulator of cellular proliferation. Mol Cell Biol 30:1171-1181

Jansen MS et al. (2014) Short-chain fatty acids enhance nuclear receptor activity through mitogen-activated protein kinase activation and histone deacetylase inhibition Proc Natl Acad Sci USA 101:7199-7204

Wu JT et al. (2001) Transient vs prolonged histone hyper acetylation: effects on colon cancer cell growth, differentiation, and apoptosis. Am J Physiol Gastrointest Liver Physiol 280:G482-G490

Han JW et al. (2001) Activation of p21^WAF1/Cip1 transcription through Sp1 sites by histone deacetylase inhibitor apicidin: involvement of protein kinase C. J Biol Chem 276:42084-42090

Han JW et al. (2000) Apidin, a histone deacetylase inhibitor, inhibits proliferation of tumor cells via induction of p21^WAF1/Cip1 and gelsolin. Cancer Res 60:6068-6074

Wade MG et al. (2008) Methoxyacetic acid-induced spermatocyte death is associated with histone hyperacetylation in rats. Biol Reprod 78:822-831

Chen S et al (2011) Histone deacetylase (HDAC) activity for embryonic kidney gene expression, growth, and differentiation. J Biol Chem 286: 32775-32789

Relationship: 1711: p21 expression, increase leads to cell cycle disorder

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

DNA replication in Xenopus was suppressed by the GST fusion protein of p21 without amino acids 17-24 or the peptide containing cyclin binding site in N-terminus of p21 protein (Chen). P21 regulates the E2F transcriptional activity to control cell cycle in human U2OS osteosarcoma cells (Homo sapiens) (Delavaine L and La Thangue NB). Cell cycle is regulated by p21 through cyclins and CDKs in mice (Mus musculus) (Sherr CJ and Roberts JM).

Key Event Relationship Description

Cell cycle regulation through p21 activation is demonstrated by the interactions of p21 with cyclins (Dotto). P21 interacts directly with cyclins through a conserved region in close to its N-terminus (amino acids 17-24; Cy1) (Dotto). P21 has second weak cyclin binding domain near its C-terminus region (amino acids 153-159), which overlaps with its PCNA binding domain (Dotto). P21 has a separate cyclin-dependent kinase 2 (CDK2) binding site in its N-terminus region (amino acids 53-58) and optimal cyclin/CDK inhibition requires binding by this site as well as one of the cyclin binding sites (Dotto). Kinase activity of cyclin-Cdk kinase was inhibited by Cy1 site of p21 that is important for the interaction of p21 with cyclin-Cdk complexes (Chen). The peptide containing Cy1 site inhibited the kinase activity of cyclin E-Cdk2 and cyclin A-Cdk2 (Chen). The p21^{WAF1/CIP1/sdi1} gene product inhibits the cyclin D/cdk4/6 and the cyclin E/cdk2 complexes in response to DNA-damage, resulting in G₁/S arrest [Moussa, Ogryzko]. P21 inhibits cyclin-dependent kinases and regulates cell cycle to promote cell cycle arrest.

Evidence Supporting this KER

The study using the p21 deficient lungs showed that p21 is essential for the survival under hyperoxia and protects the lung from oxidative stress (O’Reilly). Hyperoxia inhibits DNA replication through p21 and histone H3 expression (O’Reilly). Hyperoxia decreased proliferation in p21 wild-type lungs but not in p21-deficient mice, which suggests that p21 is crucial for cell cycle regulation (O’Reilly).

TSA induces p21 expression leading to cell cycle arrest (Gartel). Butyrate induced p21 and apoptosis in human colon tumor cell lines, whereas the absence of p21 increased the apoptosis in HCT116 colon carcinoma cell line, which indicates that p21 has a repressive effect for butyrate-induced apoptosis and protects the cells from butyrate-induced cell death (Gartel). SAHA induced p53-independent p21 expression and apoptosis in myelomonocytic leukemia cells (Gartel). The SAHA-related lethality was increased by anti-sense p21, which indicates a protective role of p21 against SAHA-induced apoptosis (Gartel).

The up-regulation of p21 signaling and in testicular germ cells was observed in diabetes (Kilarkaje N). The dual roles of p21 in cell cycle arrest and antiapoptotic effect in the testicular germ cells of diabetic rats are suggested (Kilarkaje N). TSA promotes apoptosis via HDAC inhibition and p53 signaling pathway activation [Deng Z et al]. It is suggested that furazolidone induces reactive oxygen species leading to suppression of p-AKT and p21, and induction of apoptosis (Deng). The anti-apoptotic effect of p21 is mediated by caspase-3 inhibition, which demonstrates the possibility of cell-cycle independent effect on apoptosis (Deng). A study investing the effects of miR-6734 that has a sequence homology with a specific region of p21^WAF1/CIP1 promoter on HCT-116 colon cancer cell growth indicated that miR-6734 up-regulated p21 gene expression and induced cell cycle arrest (Kang). This result suggests that the direct enhancement of p21 gene expression is related to the alteration of the cell cycle distribution (Kang). It has been demonstrated that p21 induces apoptosis in human cervical cancer cell lines (Tsao), whereas p21 is implicated in apoptosis inhibition by blocking activation of caspase-3 or interacting with ASK1 (Gartel AL, Zhang J). The study of postnatal telomere indicated that dysfunction of premature telomere induces cell-cycle arrest through p21 activation in mammalian cardiomyocytes (Aix). The proposed model showed that telomere inactivation showed reduced regenerative capacity by p21 activation and cell cycle arrest (Aix). Up-regulation of p21 is implicated in the activation of DNA damage pathways, and deletion of p21 improved stem cell function and lifespan without accelerating chromosomal instability, which indicates that p21-dependent checkpoint induction affects the longevity limit (Choudhury AR). The p21^{WAF1/CIP1/sdi1} gene product inhibits the cyclin D/cdk4/6 and the cyclin E/cdk2 complexes in response to DNA-damage, resulting in G₁/S arrest [Moussa, Ogryzko]. G₁/S transition blockade was observed in MAA-treated prostate cancer cells [Parajuli].

References

Dotto GP (2000) p21^WAF1/Cip1: more than a break to the cell cycle? Biochim Biophys Acta 1471: M43-M56

Chen J et al (1996) Cyclin-binding motifs are essential for the function of p21^CIP1. Mol Cell Biol 16: 4673-4682

Moussa RS et al. (2015) Differential targeting of the cyclin-dependent kinase inhibitor, p21CIP/WAF1, by chelators with anti-proliferative activity in a range of tumor cell-types. Oncotarget 6:29694-29711

Ogryzko VV et al. (1997) WAF1 retards S-phase progression primarily by inhibition of cyclin-dependent kinases. Mol Cell Biol 17:4877-4882

O’Reilly MA et al (2001) The cyclin-dependent kinase inhibitor p21 protects the lung from oxidative stress. Am J Respir Cell Mol Biol 24: 703-710

Gartel AL and Tyner AL (2002) The role of the cyclin-dependent kinase inhibitor p21 in apoptosis. Mol Cancer Ther 1: 639-649

Kilarkaje N and Al-Bader MM. (2015) Diabetes-Induced Oxidative DNA Damage Alters p53-p21^CIP1/Waf1 Signaling in the Rat Testis. Reproductive Sciences 22: 102–112

Deng Z et al. (2016) Histone deacetylase inhibitor trichostatin A promotes the apoptosis of osteosarcoma cells through p53 signaling pathway activation. Int J Biol Sci 12:1298-1308

Deng S et al (2016) P21^Waf1/Cip1 plays a critical role in furazolidone-induced apoptosis in HepG2 cells through influencing the caspase-3 activation and ROS generation. Food Chem Toxicol 88: 1-12

Kang MR et al (2016) miR-6734 up-regulates p21 gene expression and induces cell cycle arrest and apoptosis in colon cancer cells. PLoS One 11: e0160961

Tsao YP et al (1999) Adenovirus-mediated p21^{WAF1/SDII/CIP1} gene transfer induces apoptosis of human cervical cancer cell lines. J Virology 73: 4983-4990

Zhan J et al (2007) Negative regulation of ASK1 by p21Cip1 involves a small domain that includes serine 98 that is phosphorylated by ASK1 in vivo. Mol Cell Biol 27: 3530-3541

Aix E et al (2016) Postnatal telomere dysfunction induces cardiomyocyte cell-cycle arrest through p21 activation. J Cell Biol 213: 571-583

Choudhury AR et al (2007) Cdkn1a deletion improves stem cell function and lifespan of mice with dysfunctional telomeres without accelerating cancer formation. Nat Genet 39: 99-105

Parajuli KR et al. (2014) Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis. Am J Clin Exp Urol 2:300-313

Delavaine L and La Thangue NB (1999) Control of E2F activity by p21Waf1/Cip1. Oncogene 18: 5381-5392

Sherr CJ and Roberts JM (2004) Living with or without cyclins and cyclin-dependent kinases. Gene Dev 18: 2699-2711

Relationship: 1712: cell cycle disorder leads to Apoptosis

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

MicroRNA let-7a induced cell cycle arrest, inhibited CCND2 and proliferation of human prostate cancer cells (Homo sapiens) (Dong Q). microRNA-497 down-regulated CCND2 and induced apoptosis via the Bcl-2/Bax-caspase 9- caspase 3 pathway in HUVECs (Homo sapiens) (Wu R). micoRNA-26a regulated p53-mediated apoptosis and CCND2 and CCNE2 in mouse hepatocyte (Mus musculus) (Zhou J).

Key Event Relationship Description

SEE BIOLOGICAL PLAUSIBILITY

Evidence Supporting this KER

Apoptosis, also called as “physiological cell death”, is involved in cell turnover, physiological involution and atrophy of various tissues and organs (Kerr JFR). The formation of apoptotic bodies involves marked condensation of both nucleus and cytoplasm, nuclear fragmentation, and separation of protuberances (Kerr JFR). The incidence of apoptosis was increased in vincristine-treated cells, in which metaphases were arrested, compared to untreated cells, which indicates that cell cycle dysregulation leads to apoptosis (Sarraf CE). Cell cycles characterized by the DNA content changes regulate cell death and cell proliferation (Lynch MP). Cell gain and loss are balanced with mitosis and apoptosis (Cree). Apoptosis is mediated by caspase activation (Porter AG). Caspase-3 is activated in the programmed cell death, and the pathways to caspase-3 activation include caspase-9 and mitochondrial cytochrome c release (Porter AG). The activation of caspase-3 leads to apoptotic chromatin condensation and DNA fragmentation (Porter AG). Sinularin, a marine natural compound, exhibited DNA damage and induced G₂/M cell cycle arrest, followed by apoptosis in human hepatocellular carcinoma HepG2 cells (Chung TW). Sinularin induced caspases 8, 9, and 3, and pro-apoptotic protein Bax, whereas it decrease the anti-apoptotic Bcl-2 protein expression level (Chung TW). The p21^CIP1/Waf1 induces cell cycle arrest, whereas the up-regulation of p21 signaling in testicular germ cell cytoplasm is suggested to promote antiapoptotic effect for DNA damage-induced cell death in diabetes (Kilarkaje N). microRNA-497, potentially targeting Bcl2 and Cyclin D2 (CCND2), induced apoptosis via the Bcl-2/Bax - caspase 9 - caspase 3 pathway and CCND2 protein in human umbilical vein endothelial cells (HUVECs) (Wu R). The microRNA-497 activated caspases 9 and 3, and decreased Bcl2 and CCND2 (Wu R). CCND2 is an important cell cycle gene that induces G₁ arrest (Li L), and deregulated CCND2 is implicated in cell proliferation inhibition (Wu R, Mermelstein A, Dong Q).

Cell cycle arrest such as G₁ arrest and G₁/S arrest are observed in apoptosis (Li L, Dong Q). microRNA-1 and microRNA-206 represses CCND2, while microRNA-29 represses CCND2 and induces G₁ arrest and apoptosis in rhabdomyosarcoma (Li L). The treatment with MAA in prostate cancer cells induced growth arrest and apoptosis [Parajuli].

microRNA-497 induce activation of caspase-9 and -3, followed by apoptosis, however, the caspase-9 and -3 protein levels were repressed by the ectopic expression of microRNA-497, which remains uncertain (Wu R).

References

Kerr JFR et al. (1972) Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics. Br J Cancer 26: 239-257

Sarraf CE and Bowen ID (1986) Kinetic studies on a murine sarcoma and an analysis of apoptosis. Br J Cancer 54: 989-998

Lynch MP et al. (1986) Evidence for soluble factors regulating cell death and cell proliferation in primary cultures of rabbit endometrial cells grown on collagen. Proc Natl Acad Sci USA 83: 4784-4788

Cree IA et al. (1987) Cell death in granulomata: the role of apoptosis J Clin Pathol 40: 1314-1319

Porter AG and Janicke RU. (1999) Emerging roles of caspase-3 in apoptosis. Cell Death Differ 6: 99-104

Chung TW et al. (2017) Sinularin induces DNA damage, G2/M phase arrest, and apoptosis in human hepatocellular carcinoma cells. BMC Complement Altern Med 17: 62

Kilarkaje N and Al-Bader MM. (2015) Diabetes-Induced Oxidative DNA Damage Alters p53-p21^CIP1/Waf1 Signaling in the Rat Testis. Reproductive Sciences 22: 102–112

Wu R et al. (2016) microRNA-497 induces apoptosis and suppressed proliferation via the Bcl-2/Bax-caspase9-caspase 3 pathway and cyclin D2 protein in HUVECs. PLoS One 11: e0167052

Li L et al. (2012) Downregulation of microRNAs miR-1, -206 and -29 stabilizes PAX3 and CCND2 expression in rhabdomyosarcoma. Lab Invest 92: 571-583

Mermelshtein A et al. (2005) Expression of F-type cyclins in colon cancer and in cell lines from colon carcinomas. Br J Cancer 93: 338-345

Dong Q et al. (2010) microRNA let-7a inhibits proliferation of human prostate cancer cells in vitro and in vivo by targeting E2F2 and CCND2. PLoS One 5: e10147

Parajuli KR et al. (2014) Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis. Am J Clin Exp Urol 2:300-313

Zhou J et al. (2016) miR-26a regulates mouse hepatocyte proliferation via directly targeting the 3’ untranslated region of CCND2 and CCNE2. Hepatobiliary Pancreat Dis Int 15: 65-72

Relationship: 1713: Apoptosis leads to testicular toxicity

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

Spermatogenesis was inhibited by knockdown of Sucla2 via apoptosis in the mouse spermatocyte (Mus musculus) (Huang). The suppression of microRNA-21 led to apoptosis of spermatogonial stem cell-enriched germ cell cultures and the decrease in the number of spermatogonial stem cells in mice (Mus musculus) (Niu Z et al).

Key Event Relationship Description

In the mouse spermatocyte, spermatogenesis was inhibited by knockdown of Sucla2 via apoptosis (Huang). CD147 was reported to regulate apoptosis in mouse testis and spermatocyte cell line (GC-2 cells) via NFkB pathway (Wang).

Evidence Supporting this KER

Apoptosis is a basic biological phenomenon in which the cells are controlled in the atrophy of various tissues and organs through the deletion and turnover, as well as in tumor regression (Kerr JFR et al).

MicroRNA-21 regulates the spermatogonial stem cell homeostasis, in which suppression of microRNA-21 with anti-miR-21 oligonucleotides led to apoptosis of spermatogonial stem cell-enriched germ cell cultures and the decrease in the number of spermatogonial stem cells (Niu Z et al).

Spermatogonial stem cell self-renewal and spermatocyte meiosis are regulated by Sertoli cell signaling, which suggests us that various pathways other than HDAC inhibition in spermatocytes or spermatogonia are involved in the spermatocyte deletion and testis atrophy/weight loss (Chen SR). It should be noted that the process of apoptosis is necessary for the meitosis of the stem cell differentiation in the testis, which remains in question for the regulation of spermatocyte deletion and testis atrophy/weight loss (Dym M).

References

Huang S et al. (2016) Knockdown of Sucla2 decreases the viability of mouse spermatocytes by inducing apoptosis through injury of the mitochondrial function of cells. Folia Histochem Cytobiol 54: 134-142

Wang C et al. (2017) CD147 regulates extrinsic apoptosis in spermatocytes by modulating NFkB signaling pathways. Oncotarget 8: 3132-3143

Kerr JFR et al. (1972) Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics. Br J Cancer 26: 239-257

Niu Z et al. (2011) microRNA-21 regulates the self-renewal of mouse spermatogonial stem cells. Proc Natl Acad Sci 108: 12740-12745

Chen S and Liu Y. (2015) Regulation of spermatogonial stem cell self-renewal and spermatocyte meiosis by Sertoli cell signaling. Reproduction 149: R159-R167

Dym M. (1994) Spermatogonial stem cells of the testis. Proc Natl Acad Sci USA 91: 11287-11289

De Rooij DG et al. (2001) Proliferation and differentiation of spermatogonial stem cells. Reproduction 121: 347-354

De Rooij DG. (1998) Stem cells in the testis. Int J Exp Path 79: 67-80

Relationship: 1714: Histone deacetylase inhibition leads to p21 expression, increase

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

The exposure of 2-MAA on mouse limbs in vitro induced histone hyperacetylation and p21 expression increase (Mus musculus) (Dayan). HDAC-deficient embryonic stem cells demonstrated up-regulation of p21 in mice (Mus musculus) (Lagger). HDAC inhibitor, AR-42 induced histone hyperacetylation and p21 up-regulation in human pancreatic cancer cells (Homo sapiens) (Henderson).

Key Event Relationship Description

HDAC inhibition leads to histone hyperacetylation and p21 activation (Falkenberg KJ, 2014). HDIs-induced G₁/S phase arrest occurs primarily through transcriptional changes in cell cycle regulatory genes, such as induction of the CDK inhibitors p21 (CDKN1A), p15^INK4B (CDKN2B), p19^INK4D (CDKN2D) and p57 (CDKN1C) (Falkenberg 2014). HDAC1-deficient embryonic stem cells showed decrease in cyclin-associated kinase activities and increase in p21^WAF1/CIP1 (Lagger G). Expression of p21 is up-regulated in HDAC1-null embryos (Lagger G). The HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA), trichostatin A (TSA), and MS-27-275 induced histone hyperacetylation and p21 up-regulation (Glaser). MAA up-regulated p21 mRNA level and acetylation of histone H3 and H4 (Parajuli KR).

Evidence Supporting this KER

In human pancreatic cancer cell lines, p21 up-regulation and histone H3 hyperacetylation by HDAC inhibitor AR-42 were observed (Henderson). Furthermore, the oral administration of AR-42 at 50 mg/kg resulted in suppression of tumor in the pancreatic cancer cell xenograft and transgenic KP^fl/flC (LSL-Kras^G12D; Trp53^flox/flox; Pdx-1-Cre) mouse model (Henderson). The exposure of 2-methoxyacetic acid (2-MAA) induced morphological changes on embryonic forelimbs (Dayan).

The expression of p21 was up-regulated with 10 mM of 2-MAA, whereas ethylene glycol monomethyl ether (EGME) did not increase p21 expression (Dayan). The treatment of 2-MAA induced histone acetylation in H3K9Ac and H4K12Ac, as well as p53K379Ac (Dayan).

The exposure to 2-MAA induced p53 acetylation independent of histone hyperacetylation, which demonstrates the possibility in which several pathways are activated in HDAC inhibition towards apoptosis (Dayan). It has also been shown that p21 up-regulation by sodium butyrate is p53 dependent using the Chromatin Immunoprecipitation (ChIP) assay with anti-p53 monoclonal antibody (Saldanha). ST2783, a HDI, induced acetylation of p53 (Zuco). The mechanism inducing p21 by HDAC inhibition contains several pathway cross-talk.

References

Falkenberg KJ and Johnstone RW. (2014) Histone deacetylases and their inhibitors in cancer, neurological disease and immune disorders. Nat Rev Drug Discov 13:673-691

Lagger G et al. (2002) Essential function of histone deacetylase 1 in proliferation control and CDK inhibitor repression. EMBO J 21:2672-2681

Glaser KB et al. (2003) Gene expression profiling of multiple histone deacetylase (HDAC) inhibitors: defining a common gene set produced by HDAC inhibition in T24 and MDA carcinoma cell lines. Mol Cancer Ther 2:151-163

Parajuli KR et al. (2014) Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis. Am J Clin Exp Urol 2:300-312

Henderson SE et al. (2016) Suppression of tumor growth and muscle wasting in a transgenic mouse model of pancreatic cancer by the novel histone deacetylase inhibitor AR-42. Neoplasia 18:765-774

Dayan C and Hales BF. (2014) Effects of Ethylene glycol monomethyl ether and its metabolite, 2-methoxyacetic acid, on organogenesis stage mouse limbs in vitro. Birth Defects Res 101:254-261

Saldanha SN et al. (2014) Molecular mechanisms for inhibition of colon cancer cells by combined epigenetic-modulating epigallocatechin gallate and sodium butyrate. Exp Cell Res 324:40-53

Zuco V et al. (2011) Synergistic antitumor effects of novel HDAC inhibitors and paclitaxel in vitro and in vivo. PLoS One 6:e29085

Kaur J and Tikoo K. (2013) p300/CBP dependent hyperacetylation of histone potentials anticancer activity of gefitinib nanoparticles. Biochimica et Biophysica Acta 1833:1028-1040

Relationship: 1715: Histone deacetylase inhibition leads to cell cycle disorder

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

MAA induced G₁ cell cycle arrest in human prostate cancer cells (Homo sapiens) (Parajuli). Apicidin-induced G₁ cell cycle arrest in HeLa cells (Homo sapiens) (Han).

Key Event Relationship Description

Apicidin [cyclo(N-O-methyl-L-tryptophanyl-L-isoleucinyl-D-pipecolinyl-L-2-amino-8-oxodecanoyl)], a fungal metabolite HDI, inhibits proliferation of tumor cells via p21 induction (Han JW). Apicidin induced hyperacetylation of histone H4, up-regulation of p21, and G₀/G₁ cell cycle arrest in HeLa cells (Han JW). HDAC inhibition leads to cell cycle arrest, where G₁/S phase arrest occurs with up-regulation of p21 (Falkenberg).

Evidence Supporting this KER

Loss of HDAC1 in mouse embryonic stem (ES) cells has demonstrated the acetylation of histones H3 and H4, up-regulation of cyclin-dependent kinase inhibitors p21^WAF1/CIP1 and p27^KIP1 and inhibition of proliferation (Lagger).

In HDAC1^-/- fibroblast lines, increase in the amount of cells in G₁ phase and decrease in the amount of cells in S phase were observed, which indicates the importance of HDAC inhibition in cell cycle regulation [Zupkovitz]. HDAC inhibition with SAHA, TSA and MS-27-275 induced acetylation of histone H4, up-regulation of cyclin-dependent kinase inhibitor p21, and inhibition of proliferation in human bladder carcinoma cells (Glaser).

MAA, a HDI, induced cell cycle arrest and up-regulation of p21 expression, and inhibited prostate cancer cell growth (Parajuli). The involvement of p53/p63/p73 in up-regulation of p21 induced by HDAC inhibition is not fully elucidated, where time course of the p21 and p53/p63/p73 mRNA expression has demonstrated the cell-line specific differences in the responses in 4 human prostate cancer cell lines LNCaP, C4-2B, PC-3 and DU-145 (Parajuli).

References

Han JW et al. (2000) Apicidin, a histone deacetylase inhibitor, inhibits proliferation of tumor cells via induction of p21^WAF1/Cip1 and gelsolin. Cancer Res 60:6068-6074

Falkenberg KJ and Johnstone RW. (2014) Histone deacetylases and their inhibitors in cancer, neurological disease and immune disorders. Nat Rev Drug Discov 13:673-691

Lagger G et al. (2002) Essential function of histone deacetylase 1 in proliferation control and CDK inhibitor repression. EMBO J 21:2672-2681

Zupkovitz G et al. (2010) The cyclin-dependent kinase inhibitor p21 is a crucial target for histone deacetylase 1 as a regulator of cellular proliferation. Mol Cell Biol 30:1171-1181

Glaser KB et al. (2003) Gene expression profiling of multiple histone deacetylase (HDAC) inhibitors: defining a common gene set produced by HDAC inhibition in T24 and MDA carcinoma cell lines. Mol Cancer Ther 2:151-163

Parajuli KR et al. (2014) Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis. Am J Clin Exp Urol 2:300-312

Relationship: 1716: Histone deacetylase inhibition leads to Apoptosis

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

AR-42 inhibited proliferation of human pancreatic cancer cells (Homo sapiens) (Henderson). SAHA inhibited proliferation of NHDF (Homo sapiens) (Glaser). MAA induced apoptosis in human prostate cancer cell lines (Homo sapiens) (Parajuli). HDAC-deficient mouse ES cells showed decrease in proliferation (Mus musculus) (Lagger).

Key Event Relationship Description

HDAC inhibition leads to cell death through the apoptotic pathways (Falkenberg). Intrinsic apoptosis pathway requires BH3-only proteins, and BCL-2 protein overexpression inhibits apoptosis (Falkenberg). MAA-induced spermatocyte death is associated with histone acetylation increase (Wade 2008). The HDAC inhibition induced p21 up-regulation, histone acetylation increase, and apoptosis markers such as BAK overexpression and suppression of phosphorylated AKT (Henderson). AR-42 inhibited the expression of BCL-X_L, an anti-apoptotic molecule in AsPC-1 tumor homogenates collected after 21 days of treatment (Henderson).

Evidence Supporting this KER

Oral administration of AR-42, a HDAC inhibitor, at 50 mg/kg in human pancreatic cancer cell AsPC-1 xenograft and KP^fl/flC models resulted in the suppression of tumor (Henderson).

HDAC-deficient mouse embryonic stem (ES) cells showed reduced proliferation rates with up-regulation of cyclin-dependent kinase inhibitors p21 and p27 (Lagger). HDAC-null embryoid bodies showed a reduced inner cell mass and reduced colony formation (Lagger). HDAC inhibition by suberoylanilide hydroxamic acid (SAHA) inhibited proliferation of normal human dermal fibroblasts (NHDF) (Glaser).

Methoxyacetic acid (MAA), a HDAC inhibitor, induced cell cycle arrest, apoptosis, leading to suppression of human prostate cancer cell growth (Parajuli). It is not fully elucidated whether MAA-induced apoptosis is involved in p53/p63/p73 pathway (Parajuli).

References

Falkenberg KJ and Johnstone RW. (2014) Histone deacetylases and their inhibitors in cancer, neurological disease and immune disorders. Nat Rev Drug Discov 13:673-691

Wade MG et al. (2008) Methoxyacetic acid-induced spermatocyte death is associated with histone hyperacetylation in rats. Biol Reprod 78:822-831

Henderson SE et al. (2016) Suppression of tumor growth and muscle wasting in a transgenic mouse model of pancreatic cancer by the novel histone deacetylase inhibitor AR-42. Neoplasia 18:765-774

Lagger G et al. (2002) Essential function of histone deacetylase 1 in proliferation control and CDK inhibitor repression. EMBO J 21:2672-2681

Glaser KB et al. (2003) Gene expression profiling of multiple histone deacetylase (HDAC) inhibitors: defining a common gene set produced by HDAC inhibition in T24 and MDA carcinoma cell lines. Mol Cancer Ther 2:151-163

Parajuli KR et al. (2014) Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis. Am J Clin Exp Urol 2:300-312

Relationship: 1717: Histone deacetylase inhibition leads to testicular toxicity

AOPs Referencing Relationship

Evidence Supporting Applicability of this Relationship

The administration of di(2-ethylhexyl)-phthalate induced testis atrophy in rats (Rattus norvegicus) (Oishi 1994). The administration of butylparaben resulted in decrease in sperm counts in rats (Rattus norvegicus) (Oishi 2001).

Key Event Relationship Description

MAA induced spermatocyte death with an association of histone acetylation increase (Wade 2008). Doxorubicin, which has a testicular toxicity, induced caspase 3 activation and g-H2AX induction, apoptosis markers, in human lung cancer A549 cells (El-Awady, Yamazoe). Doxorubicin-resistant A549 cells showed reduced expression of HDAC1, 3 and 4 compared to A549 cells (El-Awady). Methoxyacetic acid (MAA)-induced apoptosis in male germ cells was modulated by Sertoli cells via P/Q type voltage-operated calcium channels (Barone F).

Evidence Supporting this KER

The p.o. administration of ethylene glycol monomethyl (500 mg/kg/day) in rats induced the testis or liver organ weight loss on 2, 4, 7 and 11 days or 24 hrs and 2, 4 and 7 days after treatment, respectively (Foster PMD 1983). The investigation of 2-methoxyethanol (2-ME)-induced testicular toxicity has revealed that the conversion of 2-ME to methoxyacetic acid (MAA) is required in 2-ME-induced testicular toxicity (Moss).

MAA (300 mg/kg) induced body weight loss and testicular toxicity measured with testis weight loss (Miller). MAA induced apoptosis and degeneration in spermatocytes in human testicular tissue and 25-day rat seminiferous tubule cultures (Li).

Methyl and ethyl esters of p-hydroxybenzoic acid did not show spermatotoxic effects in rats (Rattus norvegicus) (Oishi 2004). It is reported that HDAC inhibition leads to teratogenic toxicity, whereas the correlation with testicular toxicity and teratogenic toxicity by HDAC inhibition is not fully understood (Menegola). The oral administration of vorinostat (SAHA), a HDAC inhibitor, in Sprague-Dawley rats showed no indication of reproductive toxicity in drug-treated male rats, which suggested the involvement of some compensation mechanisms or digestion (Wise).

References

Wade MG et al. (2008) Methoxyacetic acid-induced spermatocyte death is associated with histone hyperacetylation in rats. Biol Reprod 78:822-831

El-Awady RA et al. (2015) Epigenetics and miRNA as predictive markers and targets for lung cancer chemotherapy. Cancer Biol Ther 16: 1056-1070

Yamazoe Y. et al. (2015) Embryo- and testicular-toxicities of methoxyacetate and the related: a review on possible roles of one-carbon transfer and histone modification. Food Safety 3:92-107

Barone F. et al. (2005) Modulation of MAA-induced apoptosis in male germ cells: role of Sertoli cell P/Q-type calcium channels. Reprod Biol Endocrinol 3:13

Foster PM et al. (1983) Testicular toxicity of ethylene glycol monomethyl and monoethyl ethers in the rat. Toxicol Appl Pharmacol 69:385-399

Moss EJ et al. The role of metabolism in 2-methoxyethanol-induced testicular toxicity. Toxicol Appl Pharmacol 79:480-489

Miller RR et al. (1982) Toxicity of methoxyacetic acid in rats. Fundam Appl Toxicol 2: 158-160

Li LH et al. (1996) 2-Methoxyacetic acid (MAA)-induced spermatocyte apoptosis in human and rat testes: an in vitro comparison. J Androl 17: 538-549

Oishi S. (2004) Lack of spermatotoxic effects of methyl and ethyl esters of p-hydroxybenzoic acid in rats. Food Chem Tox 42: 1845-1849

Menegola E et al. (2006) Inhibition of histone deacetylase as a new mechanism of teratogensis. Birth Defects Res 78: 345-353

Wise LD et al. (2008) Assessment of female and male fertileity in Sprague-Dawley rats administered vorinostat, a histone deacetylase inhibitor. Birth Defects Res B Dev Reprod Toxicol 83: 19-26

Foster PM et al. (1984) Testicular toxicity produced by ethylene glycol monomethyl and monoethyl esters in the rat. Environ Health Perspect 57: 207-217

Oishi S. (1994) Prevention of Di(2-ethylhexyl)phthalate-induced testicular atrophy in rats by co-administration of the vitamin B12 derivative denosylcobalamin. Arch Environ Contam Toxicol 26: 497-503

Oishi S. (2001) Effects of butylparaben on the male reproductive system in rats. Tox Industr Health 17: 31-39