Apoptotic and Cytotoxic Effect of Nisin on Triple-Negative Breast Cancer Cell Line, MDA-MB-231: One Health-Oriented Strategy for Cancer Control

Abstract

Background: As one of the most prevailing cancer types, the hostile nature of breast cancer presents itself with
significant treatment challenges besides becoming resilient toward conventional therapeutic strategies, demanding
an urgent need for a better treatment option. Objectives: Hence, the study explores the anticancer potential of
nisin, a bacteriocin, synthesized by Lactococcus lactis. Materials and Methods: L. lactis, prebiotic sourced from
curd, was exposed to triple negative breast cancer (TNBC) cell line, MDA-MB-231, and its cytotoxic and apoptotic
effects were evaluated. Nisin was isolated from L. lactis strain LB11 and confirmed by spectrophotometric assay
(220 nm) through comparison with standard. Nisin was then carried forward for cytotoxic assay. Results: This
revealed its ability to endorse a dose-dependent toxicity on TNBC cells (IC50 24.959 μg/mL) that were affirmed
by the morphological changes observed in treated cells such as shrinkage and loss of spindle shape, attributed
to membrane damage instigated by exposure to nisin. This was also further supported by fluorescence imaging
studies that showed treated cells with both chromatin condensation and nuclear fragmentation, confirming early
as well as late apoptosis. Negative effect of nisin on mitochondrial membrane potential of treated cancer cells
confirmed by progressive loss of fluorescence, indicative of intrinsic apoptotic pathway, along with caspase
activation. Conclusion: These results hence affirm the capabilities of nisin to invoke cytotoxicity and apoptosis in
TNBC cells, to be used as a prospective therapeutic agent for breast cancer, aligning with sustainable development
goal of good health and well-being. However, additional studies are required to establish its suitability as an
alternative to conventional therapies.