Journal Article

SETDB1 interactions with PELP1 contributes to breast cancer endocrine therapy resistance

Tang, Weiwei, He, Yi, Li, Xiaonan, Liu, Zexuan, Shen, Liangfang, Rao, Manjeet K., Liu, Junhao, Pratap, Uday P., Chen, Yidong, Ebrahimi, Behnam, Viswanadhapalli, Suryavathi, Tekmal, Rajeshwar R., Lai, Zhao, Altwegg, Kristin A., Sareddy, Gangadhara R., Vadlamudi, Ratna K.

2022

Overview

Background Methyltransferase SETDB1 is highly expressed in breast cancer (BC), however, the mechanisms by which SETDB1 promotes BC progression to endocrine therapy resistance remains elusive. In this study, we examined the mechanisms by which SETDB1 contribute to BC endocrine therapy resistance. Methods We utilized therapy sensitive (MCF7 and ZR75), therapy resistant (MCF7-TamR, MCF7-FR, MCF7-PELP1cyto, MCF7-SETDB1) estrogen receptor alpha positive (ER + )BC models and conducted in vitro cell viability, colony formation, 3-dimensional cell growth assays to investigate the role of SETDB1 in endocrine resistance. RNA-seq of parental and SETDB1 knock down ER +  BC cells was used to identify unique pathways. SETDB1 interaction with PELP1 was identified by yeast-two hybrid screen and confirmed by immunoprecipitation and GST-pull down assays. Mechanistic studies were conducted using Western blotting, reporter gene assays, RT-qPCR, and in vitro methylation assays. Xenograft assays were used to establish the role of PELP1 in SETDB1 mediated BC progression. Results RNA-seq analyses showed that SETDB1 regulates expression of a subset of estrogen receptor (ER) and Akt target genes that contribute to endocrine therapy resistance. Importantly, using yeast-two hybrid screen, we identified ER coregulator PELP1 as a novel interacting protein of SETDB1. Biochemical analyses confirmed SETDB1 and PELP1 interactions in multiple BC cells. Mechanistic studies confirmed that PELP1 is necessary for SETDB1 mediated Akt methylation and phosphorylation. Further, SETDB1 overexpression promotes tamoxifen resistance in BC cells, and PELP1 knockdown abolished these effects. Using xenograft model, we provided genetic evidence that PELP1 is essential for SETDB1 mediated BC progression in vivo. Analyses of TCGA datasets revealed SETDB1 expression is positively correlated with PELP1 expression in ER +  BC patients. Conclusions This study suggests that the PELP1/SETDB1 axis play an important role in aberrant Akt activation and serves as a novel target for treating endocrine therapy resistance in breast cancer.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Akt / AKT protein / Analysis / Antibodies / Biomedical and Life Sciences / Biomedicine / Breast cancer / Breast Neoplasms - drug therapy / Breast Neoplasms - genetics / Breast Neoplasms - metabolism / Cancer / Cancer Research / Care and treatment / Cell culture / Cell Line, Tumor / Cell Proliferation - genetics / Cell viability / Cloning / Co-Repressor Proteins - genetics / Co-Repressor Proteins - metabolism / Co-Repressor Proteins - pharmacology / DNA methylation / Drug Resistance, Neoplasm - genetics / Endocrine therapy / Estrogen / Estrogen receptors / Estrogens / Female / Fulvestrant / Gene Expression Regulation, Neoplastic / Genomes / Growth factors / Health aspects / Histone-Lysine N-Methyltransferase - genetics / Histone-Lysine N-Methyltransferase - metabolism / Histone-Lysine N-Methyltransferase - pharmacology / Humans / Immunoprecipitation / Methylation / Methyltransferase / Oncology / PELP1 / Phosphorylation / Proteins / Proto-Oncogene Proteins c-akt - metabolism / Receptors, Estrogen - genetics / Receptors, Estrogen - metabolism / Reporter gene / Research Article / RNA / Saccharomyces cerevisiae - metabolism / SETDB1 / Surgical Oncology / Tamoxifen / Tamoxifen - pharmacology / Therapy resistance / Transcription Factors - genetics / Western blotting / Xenografts