P–341 Epigenetic role of the H2BK5ac histone modification on the expression of ALX1 and PDHX genes in the endometriotic tissues and normal endometrium
Authors: Sarshomar S , Sarshomar S , Chitsazian F , Ghaffari F , Shahhoseini M , Shahhoseini M , Shahhoseini M 
Published: August 2021

Abstract

Study question
Evolution of the ALX1 and PDHX genes expression and incorporation of H2BK5ac mark on the promoter of these genes in endometriotic tissues versus normal endometrium

Summary answer
Lower incorporation of H2BK5ac mark in ALX1 and PDHX promoters can because to downregulation of these genes in endometriotic tissues compared to normal endometrium.

What is known already
Endometriosis is considered as multifactorial disease affected by genetic, hormonal, and environmental factors. Recent evidences suggest the role of epigenetic mechanisms in this disease. Aristaless-like homeobox1 (ALX1) and Pyruvate Dehydrogenase Protein X (PDHX) genes are considered in this study. Studies show that upregulation of the ALX1 gene cause cell proliferation, migration, and invasion in cancer cells. PDHX is involved in cellular metabolism and acts as a tumor suppressor gene while maintaining normal homeostasis. It is Hypothesized that H2BK5ac which is known as a dynamic marker in promoter regions of active genes, may be involved in regulation of these gene expression.

Study design, size, duration
Ten eutopic and ectopic endometrium tissue, as well as ten normal endometrium, were collected. Ectopic biopsies were obtained using diagnostic laparoscopy, while the endometrial control samples and eutopic samples were collected via pipelle.

Participants/materials, setting, methods
RNA extraction and cDNA synthesis were done then the expression of ALX1 and PDHX genes evaluated by quantitative real-time PCR. Promoter regions of mentioned genes investigated for the incorporation of the epigenetic mark of H2BK5ac using Chromatin immunoprecipitation (ChIP) followed by real-time PCR. Data analysis performed using One-way ANOVA analysis (SPSS software) considered the significant level of P &lt; 0.05.

Main results and the role of chance
Results showed that the expression of ALX1 was significantly decreased in eutopic endometrial samples compared to normal endometrium (p = 0.007). Also, there was a significant reduction in PDHX mRNA level in the eutopic and ectopic samples vs. normal endometrium (p = .017 and p =.021, respectively). The chromatin immunoprecipitation real-time PCR (ChIP PCR) analyses showed significantly lower incorporation of H2BK5ac epigenetic mark in ALX1 promoter in eutopic endometrial samples compared to normal endometrium (p = 0.007). Also, reduced incorporation of H2BK5ac at the PDHX promoter region was observed in both eutopic and ectopic endometrial samples compared to normal endometrium (p = 0.004 and p = 0.003, respectively).

Limitations, reasons for caution
The main limitation of our study is the low number of samples.
Wider implications of the findings: Our results suggest that the marked lower levels of H2BK5ac in regulatory regions of ALX1and PDHX might lead to deregulation of these genes in tissue endometriotic samples.

Trial registration number
‘not applicable’ for non-clinical trials