HOXA5 Expression Is Elevated in Breast Cancer and Is Transcriptionally Regulated by Estradiol.

Imran Hussain,Bibhu P Mishra,Hriday K Das,Robert Matthew Brothers,Monira Obaid,Samara A Bobzean,Linda I Perrotti,Prasanna G Alluri,Avisankar Chini,Paromita Deb,S M Nashir Udden,Khairul I Ansari,Subhrangsu S Mandal,Arunoday Bhan

doi:10.3389/fgene.2020.592436

Abstract

HOXA5 is a homeobox-containing gene associated with the development of the lung, gastrointestinal tract, and vertebrae. Here, we investigate potential roles and the gene regulatory mechanism in HOXA5 in breast cancer cells. Our studies demonstrate that HOXA5 expression is elevated in breast cancer tissues and in estrogen receptor (ER)-positive breast cancer cells. HOXA5 expression is critical for breast cancer cell viability. Biochemical studies show that estradiol (E2) regulates HOXA5 gene expression in cultured breast cancer cells in vitro. HOXA5 expression is also upregulated in vivo in the mammary tissues of ovariectomized female rats. E2-induced HOXA5 expression is coordinated by ERs. Knockdown of either ERα or ERβ downregulated E2-induced HOXA5 expression. Additionally, ER co-regulators, including CBP/p300 (histone acetylases) and MLL-histone methylases (MLL2, MLL3), histone acetylation-, and H3K4 trimethylation levels are enriched at the HOXA5 promoter in present E2. In summary, our studies demonstrate that HOXA5 is overexpressed in breast cancer and is transcriptionally regulated via estradiol in breast cancer cells.

Highlights

HOX genes are a highly conserved family of homeobox-containing genes that play pivotal roles in cell differentiation, development, and embryogenesis (Krumlauf, 1994; Zakany and Duboule, 2007)
In an effort to understand the potential role of HOXA5 in breast cancer, initially we examined HOXA5 expression in various cancer cells and breast cancer tissues
These analyses demonstrated that HOXA5 expression is elevated in MCF7 and T47D (ER-positive breast cancer cells) in comparison to MDAMB-231 (ER-negative breast cancer cells) (Figure 1A)

Summary

INTRODUCTION

HOX genes are a highly conserved family of homeobox-containing genes that play pivotal roles in cell differentiation, development, and embryogenesis (Krumlauf, 1994; Zakany and Duboule, 2007). RNA extraction: cells were resuspended in DEPC-treated buffer A (20 mM Tris-HCl, pH 7.9; 1.5 mM MgCl2; 10 mM KCl and 0.5 mM DTT; 0.5 mM EDTA), incubated on ice (10 min), and centrifuged. MCF7 (treated with different conditions) cells were fixed in 4% formaldehyde (15 min), followed by quenching with 125 mM glycine and washed with PBS (twice). They were lyzed (SDS lysis buffer), and the chromatin was sheared by sonication (∼150–450 bp in length, checked by agarose gel). Data was considered statistically significant when the p-value was

RESULTS

DISCUSSION

ETHICS STATEMENT