Chidamide Reverses Fluzoparib Resistance in Triple-Negative Breast Cancer Cells.

Xinyang Li,Zhiwei Liu,Yuanpei Li,Xiang Yuan,Limin Wei,Jing Li,Yukun Wang,Xinshuai Wang,Ziming Wang

doi:10.3389/fonc.2022.819714

Abstract

Poly (ADP-ribose) polymerase inhibitor (PARPi) resistance is a new challenge for antitumor therapy. The purpose of this study was to investigate the reversal effects of chidamide on fluzoparib resistance, a PARPi, and its mechanism of action. A fluzoparib-resistant triple-negative breast cancer (TNBC) cell line was constructed, and the effects of chidamide and fluzoparib on drug-resistant cells were studied in vitro and in vivo. The effects of these drugs on cell proliferation, migration, invasiveness, the cell cycle, and apoptosis were detected using an MTT assay, wound-healing and transwell invasion assays, and flow cytometry. Bioinformatics was used to identify hub drug resistance genes and Western blots were used to assess the expression of PARP, RAD51, MRE11, cleaved Caspase9, and P-CDK1. Xenograft models were established to analyze the effects of these drugs on nude mice. In vivo results showed that chidamide combined with fluzoparib significantly inhibited the proliferation, migration, and invasiveness of drug-resistant cells and restored fluzoparib sensitivity to drug-resistant cells. The combination of chidamide and fluzoparib significantly inhibited the expression of the hub drug resistance genes RAD51 and MRE11, arrested the cell cycle at the G2/M phase, and induced cell apoptosis. The findings of this work show that chidamide combined with fluzoparib has good antineoplastic activity and reverses TNBC cell resistance to fluzoparil by reducing the expression levels of RAD51 and MRE11.

Highlights

Breast cancer, the most common malignant solid tumor, is the leading cause of cancer deaths among women worldwide, with approximately 2.1 million new cases in 2020 alone [1]
We investigated the mechanism behind HDAC inhibitors (HDACi) reversal of poly (ADP-ribose) polymerase inhibitors (PARPi) resistance in breast cancer cells in the present work by constructing fluzoparib-resistant breast cancer cell lines
The results of cycle and apoptosis assays showed that the drugs block the cell cycle in the G2/M phase and induce apoptosis. These results suggest that fluzoparib combined with chidamide significantly increased the expression levels of P-CDK1 and cleaved Caspase9

Summary

Introduction

The most common malignant solid tumor, is the leading cause of cancer deaths among women worldwide, with approximately 2.1 million new cases in 2020 alone [1]. PARPi traditionally exert antitumor effects by trapping PARP on DNA, causing DNA replication forks to collapse, disrupting cell mitosis, and inducing cell death, chemoresistance to PARPi has been reported [7, 8]. The mechanisms of PARPi resistance primarily include: [1] restoration of BRCA function or the abnormal expression of DNA repair proteins, leading to the restoration of the homologous recombination repair pathway [9–12]; [2] deletion of PTIP, EZH2, and MUS81 expression or increased miR-493-5p expression, leading to stability of the replication fork [13–15]; [3] mutations in PARP1 and PARG [16, 17]; [4] creation of Pglycoprotein pumps and ATP-binding cassette drug transporters that increase drug outflow [18, 19]; and [5] mir-622 overexpression, which inhibits nonhomologous end joining [20]. Overcoming PARPi resistance is necessary to permit adequate PARPi antitumor therapy

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