Abstract 4590: Antitumor effects of histone deacetylase inhibitors on breast cancer cell viability and mammosphere formation

Abstract

Abstract Histone deacetylases (HDACs) are overexpressed in various types of primary human cancer and have become attractive targets for cancer therapy. This study aimed to evaluate the cytotoxic properties of three HDAC inhibitors (suberoylanilide hydroxamic acid (SAHA, or Vorinostat), Valproic Acid (VPA) and CAY10603) and compare them to Paclitaxel (PTX), a chemotherapy agent used to treat Triple Negative Breast Cancers (TNBCs). In the present study, drug response in the MDA-MB-231, MDA-MB-468, and MCF-10A cell lines was evaluated by cell viability assays. Apoptosis and cell cycle distribution were analyzed by flow cytometry. Mammospheres generated from MDA-MB-231 and MDA-MB-468 breast cancer cells were also subjected to drug treatment; their response was assessed under both normoxic and hypoxic conditions. We found that SAHA and CAY10603 inhibited breast cancer cell viability without significantly affecting MCF-10A cells. SAHA, CAY10603, and VPA all arrested a significant percentage of MDA-MB-231 cells at G2/M phase after 24h compared to controls. TNBC cells experienced an increase in both early and late apoptosis following treatment with the most effective concentrations of SAHA, CAY10603, and VPA (1.8µM, 2µM, and 0.4mM, respectively). SAHA proved to be the most effective drug for induction of apoptosis compared to the control, followed by CAY10603 (8.26% and 6%, 3.67%). In both TNBCs and mammospheres under hypoxic conditions, SAHA and CAY10603 down regulated HIF-1α expression significantly, but PTX did not. In contrast, VPA and PTX down regulated CTNNB1 gene expression. This study indicates that epi-drugs exert an anti-tumor effect on TNBCs, suggesting a potential role for HDAC inhibitors as novel therapeutics for breast cancer patients. Citation Format: Golnaz Asaadi Tehrani, Becca Kubick, Meenal Datta. Antitumor effects of histone deacetylase inhibitors on breast cancer cell viability and mammosphere formation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4590.