p53 mediated cell cytotoxicity and DNA damage in lung cancer cell line A549 triggered by a small peptide extracted from a probiotic strain Lacticaseibacillus casei

Antimicrobial peptides are being explored as anticancer agents due to their selectivity toward transformed cells. We evaluated a small peptide from Lacticaseibacillus casei for anti-proliferative effects on A549 lung cancer cells and investigated apoptosis-related mechanisms in vitro. Cell viability was assessed by MTT. Apoptosis-associated morphology was examined by AO/EB staining, DNA fragmentation by agarose gel electrophoresis, and gene expression by qRT-PCR (p53, BAX, BCL-2, CASP8, CASP7, CASP3). The peptide reduced A549 viability in a dose-dependent manner relative to L929 cells. AO/EB staining revealed early apoptotic nuclear morphology, and DNA fragmentation was observed. qRT-PCR showed increased p53 and BAX, increased CASP8, downregulation of CASP7, and no significant change in CASP3. Data support apoptosis that is predominantly p53/BAX-driven with limited effector caspase engagement. As per experimental evidence of the study, the peptide from Lacticaseibacillus casei has the potential to inhibit the proliferation of Lung cancer cell line A549.