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Relationship: 3562
Title
SIX1 gene expression, increased leads to SIX1 protein expression, increased
Upstream event
Downstream event
Key Event Relationship Overview
AOPs Referencing Relationship
| AOP Name | Adjacency | Weight of Evidence | Quantitative Understanding | Point of Contact | Author Status | OECD Status |
|---|---|---|---|---|---|---|
| Early-life estrogen receptor agonism leading to endometrial adenosquamous carcinoma via promotion of sine oculis homeobox 1 progenitor cells | adjacent | High | Not Specified | Travis Karschnik (send email) | Under Development: Contributions and Comments Welcome |
Taxonomic Applicability
Sex Applicability
| Sex | Evidence |
|---|---|
| Female | High |
| Unspecific |
Life Stage Applicability
| Term | Evidence |
|---|---|
| Not Otherwise Specified | |
| Adult, reproductively mature | High |
Key Event Relationship Description
Sine oculis homeobox 1 (SIX1) gene expression leads to Sine oculis homeobox 1 protein expression via standard cellular transcription and translation processes.
Evidence Collection Strategy
This Key Event Relationship was part of an Environmental Protection Agency effort to develop AOPs that establish scientifically supported causal linkages between alternative endpoints measured using new approach methodologies (NAMs) and guideline apical endpoints measured in Tier 1 and Tier 2 test guidelines (U.S. EPA, 2024) employed by the Endocrine Disruptor Screening Program (EDSP). A series of key events that represent significant, measurable, milestones connecting molecular initiation to apical endpoints indicative of adversity were identified based on scientific review articles and empirical studies. Additionally, scientific evidence supporting the causal relationships between each pair of key events was assembled and evaluated. The present effort focused primarily on empirical studies with laboratory rodents and other mammals.
Xin, Li, & Yang 2016 was used as an originating publication followed by further investigation of the bibliography and google scholar to retrieve full articles.
Evidence Supporting this KER
Biological Plausibility
Transcription and translation processes, which are foundational to virtually all protein-coding genes, apply to SIX1.
Empirical Evidence
Xin, Li, & Yang 2016 used two endometrial cell lines, HEC1B and Ishikawa, to investigate the effects of gene overexpression and knockdown on subsequent SIX1 gene and protein expression. Overexpression via plasmid transfection in the HEC1B line resulted in upregulated SIX1 protein and mRNA expression. Knockout via siRNA transfection in the Ishikawa line resulted in downregulated SIX1 protein and mRNA expression. These observations directly demonstrate alteration in in SIX1 transcript levels resulting in corresponding changes in protein levels, affirming the standard transcription and translation relationship for this gene.
Uncertainties and Inconsistencies
Known modulating factors
Quantitative Understanding of the Linkage
Response-response Relationship
Time-scale
In the case of Xin, Li, & Yang 2016, western blots and RT-qPCR were conducted 48 hours after transfection. The transcription and translation process, generally, has been shown to take anywhere from a minute to several hours to reach a functional protein.
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Taxonomic Applicability
The empirical evidence presented here is limited to human endometrial cell lines. However, given fundamental transcription and translation principles, it could be reasonably concluded that SIX1 gene expression would result in SIX1 protein expression in all species where SIX1 is present.
Lifestage Applicability
The endometrial cell lines presented in the empirical evidence originated from 39 (Ishikawa) and 71-year-old (HEC1B) female patients. Again, given fundamental transcription and translation principles, it could be reasonably concluded that SIX1 gene expression would result in SIX1 protein expression in all lifestages where SIX1 is present.
Sex Applicability
The empirical evidence presented here is limited to female patients. SIX1 is not sex-restricted however, so this relationship could be expected to occur in any sex.
References
Xin, X., Li, Y., & Yang, X. (2016). SIX1 is overexpressed in endometrial carcinoma and promotes the malignant behavior of cancer cells through ERK and AKT signaling. Oncology letters, 12(5), 3435-3440.