Abstract 4240: Combining belinostat with red grape seed extract effectively inhibits cell proliferation, induces apoptosis, and reduces tumor resistance to doxorubicin by targeting mutant KRAS and p-ERK in human breast cancer

Abstract

Abstract Breast cancer ranks as the second most prevalent type of cancer worldwide. Despite significant advancements in various therapeutic approaches, the incidence rates continue to rise due to the resistance caused by elevated levels of histone de-acetylating enzymes (HDACs). The current study aims to investigate a combination therapy involving red grape seed extract (GSE) and Belinostat (PXD101), a hydroxamate-type inhibitor of histone deacetylase (HDAC), as a novel treatment to overcome resistance in breast cancer. In vitro, Two breast cancer cell lines spanning from poorly to highly differentiated cell lines, MDA-MB-231 and ZR-75-1, were tested with PXD101, GSE, and their combined treatment with or without Doxorubicin treatments. The WST-1 assay was utilized to evaluate the potential synergies of this combination in reducing proliferation and inducing apoptosis in the tested cells. Additionally, the underlying molecular mechanisms responsible for cancer cell death were explored through western blotting, histone release assays, assessment of caspase-3 levels, and immunohistochemistry (IHC) to determine the localization of oncogenic markers. The Wst-1 combination assay revealed that the viability of PXD101/GSE treated cells significantly varied in a concentration-dependent manner compared to the control untreated cells or each compound after 48 h of treatment. The calculated combination index indicated a synergistic effect in MDA-MB-231 cells, although this was not observed in ZR-75-1 cells. Moreover, the combination treatment for up to 48h triggered apoptosis in both cell lines, as evidenced by morphological changes, histone release alterations, increased caspase-3 activity, and significant inhibition of mutant KRAS and p-ERK expression levels. Immunohistochemical analysis of β-catenin localization indicated its presence at cell-cell contacts and in the cytoplasmic compartment, contrasting with its localization in the nuclei of untreated control cells. In an in vivo study utilizing the MDA-MB-231 orthotopic xenograft model, the combined treatment exhibited remarkable anticancer activity compared to the control and individual drugs. Importantly, our findings demonstrated that the combination treatment had significant inhibitory effects on tumor growth and metastatic potential, with minimal toxicity relative to untreated control tumors. Additionally, this combination enhanced efficacy, reduced toxicity, and decreased tumor resistance to Doxorubicin after 48h of treatment. Overall, our findings propose a PXD101/GSE combination as a potential non-toxic fingerprint that exhibits promising anticancer activity against Doxorubicin resistance. This combination warrants further exploration in combination therapy for human breast cancer. Citation Format: Mariam Shaker Kerema, Sara Hassan Deghedy, Sofia Khalil, Ahmed Samir Sultan. Combining belinostat with red grape seed extract effectively inhibits cell proliferation, induces apoptosis, and reduces tumor resistance to doxorubicin by targeting mutant KRAS and p-ERK in human breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4240.