BKS-112, a Selective Histone Deacetylase 6 Inhibitor, Suppresses Triple-Negative Breast Cancer Cells via AKT/mTOR Pathway

Triple-negative breast cancer (TNBC) remains a leading cause of cancer-related mortality in women, characterized by its aggressive nature and limited therapeutic options. TNBC is defined by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression, which excludes patients from targeted endocrine and HER2-directed therapies, contributing to poor prognosis. This study investigates BKS-112, a potent histone deacetylase 6 (HDAC6) inhibitor, for its anticancer activity against TNBC using MDA-MB-231 cells. We assessed HDAC protein expression and their prognostic implications, alongside in vitro experiments analyzing cell viability, apoptosis, autophagy, and colony formation. BKS-112 exhibited dose- and time-dependent reductions in cell viability, significant morphological alterations, and decreased colony formation. The compound increased the acetylation of histones H3, H4, and α-tubulin while downregulating HDAC6 expression and activity. Additionally, BKS-112 reduced cell migration, demonstrating anti-metastatic potential. It induced G1 phase cell cycle arrest and modulated key regulators, including cyclins and cyclin-dependent kinases (CDKs). Apoptosis was promoted through mitochondrial pathways, evidenced by changes in Bcl-2, Bax, and caspase activation. BKS-112 also elevated reactive oxygen species (ROS) levels, affecting apoptosis-related PI3K/AKT signaling. Autophagy was triggered by upregulating LC3 and Atg-7 expression. Collectively, these findings suggest that BKS-112 exerts robust anticancer effects by inducing cell cycle arrest, apoptosis, and autophagy, highlighting its therapeutic promise for TNBC treatment.