Silibinin induces metabolic crisis in triple‐negative breast cancer cells by modulating EGFR‐MYC‐TXNIP axis: potential therapeutic implications

Abstract

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer with limited treatment modalities and poor prognosis. Metabolic reprogramming in cancer is considered a hallmark of therapeutic relevance. Here, we report disruption of metabolic reprogramming in TNBC cells by silibinin via modulation of EGFR-MYC-TXNIP signaling. Metabolic assays combined with LC-MS-based metabolomics revealed inhibition of glycolysis and other key biosynthetic pathways by silibinin, to induce metabolic catastrophe in TNBC cells. Silibinin-induced metabolic suppression resulted in decreased cell biomass, proliferation, and stem cell properties. Mechanistically, we identify EGFR-MYC-TXNIP as an important regulator of TNBC metabolism and mediator of inhibitory effects of silibinin. Highlighting the clinical relevance of our observations, the analysis of METABRIC dataset revealed deregulation of EGFR-MYC-TXNIP axis in TNBC and association of EGFR high-MYC high-TXNIP low signature with aggressive glycolytic metabolism and poor disease-specific and metastasisfree survival. Importantly, combination treatment of silibinin or 2deoxyglucose (glycolysis inhibitor) with paclitaxel synergistically inhibited proliferation of TNBC cells. Together, our results highlight the importance of EGFR-MYC-TXNIP axis in regulating TNBC metabolism, demonstrate the anti-TNBC activity of silibinin, and argue in favor of targeting metabolic vulnerabilities of TNBC, at least in combination with mainstay chemotherapeutic drugs, to effectively treat TNBC patients.

Multiomics integrative analysis reveals antagonistic roles of CBX2 and CBX7 in metabolic reprogramming of breast cancer

“…MDA-MB-231 and MCF7 breast cancer cell lines were procured and maintained as described previously (21). Briefly, cells were grown in DMEM media (Gibco, ThermoFisher Scientific Inc., Waltham, MA, USA) supplemented with 10% FBS (Gibco) as described (21).…”

“…MDA-MB-231 and MCF7 breast cancer cell lines were procured and maintained as described previously (21). Briefly, cells were grown in DMEM media (Gibco, ThermoFisher Scientific Inc., Waltham, MA, USA) supplemented with 10% FBS (Gibco) as described (21). For CBX2 and CBX7 silencing experiments, MDA-MB-231 and MCF7 were seeded at a density of 1x10 4 and 5x10 3 per wells, respectively, followed by transfection with siRNA SMARTpool and non-targeting pool siRNA (Dharmacon, Lafayette, CO, USA).…”

“…Cells were allowed to grow for 48 hours before processing and harvesting for experimental measurements. Glucose, lactate and ATP measurements were taken spectrophotometrically using commercial kits as described previously (21). Oligomycin (Sigma-Aldrich) was dissolved in DMSO to prepare a 5 mM stock solution and stored at -80°C until further use.…”

“…All metabolic measurements were normalized to protein content. Cell viability and biomass experiments were performed using MTT and sulforhodamine-based (SRB) assays as described (21). For proliferation assay, cells were counted using a hemocytometer.…”

“…Moreover, aerobic glycolysis and associated pathways contribute to chemoand radio-resistance in cancer (18)(19)(20). Combinatorial treatments with compounds inhibiting glycolysis have shown synergy in decreasing triple-negative breast cancer cell viability (21). Taken together, aerobic glycolysis is critical for tumor growth and survival, thus, it is important to elucidate the mechanisms that contribute to its regulation in breast cancer.…”