Synergistic effects of combined cisplatin and Clinacanthus nutans extract on triple negative breast cancer cells

OBJECTIVE: Triple negative breast cancer (TNBC) is the most invasive breast cancer subtype enriched with cancer stem cells. TNBCs do not express estrogen, progesterone, or human epidermal growth factor receptor 2 (HER2) receptors, making them difficult to be targeted by existing chemotherapy treatments. In this study, we attempted to identify the effects of combined cisplatin and Clinacanthus nutans treatment on MDA-MD-231 and MDA-MB-468 breast cancer cells, which represent TNBC subtypes. METHODS: The phytochemical fingerprint of C. nutans ethanolic leaf extract was evaluated by LC–MS/MS analysis. We investigated the effects of cisplatin (0–15.23 μg/mL), C. nutans (0–50 μg/mL), and a combination of cisplatin (3.05 μg/mL) and C. nutans (0–50 μg/mL), on cell viability, proliferation, apoptosis, invasion, mRNA expression in cancer stem cells (CD49f, KLF4), and differentiation markers (TUBA1A, KRT18) in TNBC cells. In addition, we also studied the interaction between cisplatin and C. nutans. RESULTS: Derivatives of fatty acids, carboxylic acid ester, and glycosides, were identified as the major bioactive compounds with potential anticancer properties in C. nutans leaf extract. Reductions in cell viability (0–78%) and proliferation (2–77%), as well as a synergistic anticancer effect, were identified in TNBC cells when treated with a combination of cisplatin and C. nutans. Furthermore, apoptotic induction via increased caspase-3/7 activity (MDA-MB-231: 2.73-fold; MDA-MB-468: 3.53-fold), and a reduction in cell invasion capacity to 36%, were detected in TNBC cells when compared to single cisplatin and C. nutans treatments. At the mRNA level, cisplatin and C. nutans differentially regulated specific genes that are responsible for proliferation and differentiation. CONCLUSION: Our findings demonstrate that the combination of cisplatin and C. nutans represents a potential treatment for TNBC.