C-terminal domain of human CAP18 antimicrobial peptide induces apoptosis in oral squamous cell carcinoma SAS-H1 cells.

Mammalian myeloid and epithelial cells express many antimicrobiotic peptides that contribute to innate host defense against invading microbes. In the present study, a 27-mer peptide of the C-terminal domain (hCAP18(109-135)) and analogs of the antimicrobial peptide human cathelicidin LL-37/human cationic antimicrobial protein 18 (hCAP18) were examined for tumoricidal activity. In vitro results showed that hCAP18(109-135) induced apoptosis in human oral squamous cell carcinoma (OSCC), SAS-H1 cells. The hCAP18(109-135) induced mitochondrial depolarization and apoptosis in SAS-H1 cells, but not in healthy human gingival fibroblasts (HGF) and human keratinocyte line HaCaT cells. Caspases were not activated during hCAP18(109-135)-induced apoptosis in SAS-H1 cells. The results indicate that hCAP18(109-135) may induce caspase-independent apoptosis in OSCC but not in normal cells. hCAP18(109-135) can therefore be a useful anti-tumor therapeutic agent in the treatment of OSCC.