Induction of Apoptotic Cell Death in Non-Small-Cell Lung Cancer Cells by MP28 Peptide Derived from Bryopsis plumosa

Marine algae are a prolific bioactive peptide source with a broad pharmacological potential. We characterized MP28, a cationic peptide isolated from the green alga <i>Bryopsis plumosa</i>. Structural modeling indicated a predominantly amphipathic α-helix (residues 3-16) flanked by flexible termini and stabilized by intramolecular disulfide bonds, a motif typical of membrane-active anticancer peptides. Functionally, MP28 demonstrated potent activity against non-small-cell lung cancer cell lines (A549, H460, H1299) without affecting non-tumorigenic lung fibroblasts (MRC-5). In vitro, MP28 decreased cell viability and clonogenic growth and suppressed migration and invasion in a dose-dependent manner. Flow cytometry revealed increased early/late apoptotic fractions, accompanied by caspase-9 activation, consistent with engagement of the intrinsic apoptotic pathway. In a mouse xenograft model, MP28 treatment significantly reduced tumor size compared with that of controls. Collectively, MP28 may be a potent anticancer peptide that exhibits selective cytotoxicity and low toxicity toward normal cells.