Tilapia (Oreochromis mossambicus) antimicrobial peptide, hepcidin 1-5, shows antitumor activity in cancer cells

The inhibitory function of tilapia hepcidin (TH)1-5, an antimicrobial peptide, was not examined in previous studies. In this study, we synthesized the TH1-5 peptide and tested TH1-5's antitumor activity against several tumor cell lines. We show that TH1-5 inhibited the proliferation of tumor cells and reduced colony formation in a soft agar assay. Scanning electron microscopy and transmission electron microscopy showed that TH1-5 altered the membrane structure similar to the function of a lytic peptide. Acridine orange/ethidium bromide staining, a wound-healing assay, and a flow cytometric analysis showed that TH1-5 induced necrosis with high-concentration treatment and induced apoptosis with low-concentration treatment. Inflammation is known to be closely associated with the development of cancer. TH1-5 showing anti-inflammatory effects in a previous publication induced us to evaluate the anti-inflammatory effects in cancer cell lines through the expressions of immune-related genes after being treated with the TH1-5 peptide. However, real-time qualitative RT-PCR indicated that TH1-5 treatment induced downregulation of the expressions of interleukin (IL)-6, IL-8, IL-12, IL-15, interferon-γ, CTSG, caspase-7, and Bcl-2, and upregulation of IL-2 and CAPN5 in HeLa cells, and upregulation of IL-8 and CTSG in HT1080 cells. These results suggest that TH1-5 possibly induces an inflammatory response in HeLa cells, but not in HT1080 cells. Overall, these results indicate that TH1-5 possesses the potential to be a novel peptide for cancer therapy.