[Effects of the antibacterial peptide cecropins from Chinese oak silkworm, Antheraea pernyi on 1, 2-dimethylhydrazine-induced colon carcinogenesis in rats].

Objective: To gain insight into the putative anticancer effect of the antibacterial peptides, cecropins, from Chinese oak silkworm, Antheraea pernyi, on the cancer cells and 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats.

Methods: Growth inhibitory effect of the cecropins on normal human gastric epithelial cell line (GES-1) and human colon adenocarcinoma cell line (LS-174T) was observed using a microculture tetrazolium (MTT) colorimetric methods. Male Wistar rats were divided into 4 groups. Group1 was given on a weekly basis cecropins from Antheraea pernyi (3,000 Ua/ml) by gavage at 2 doses of 10 ml/kg body weight and exposed to subcutaneous injection of DMH at the dose of 20 mg/kg body weight. Group 2 was received weekly DMH only. Group 3 was given the cecropins by gavage at the same dose as in group 1. Group 4 was weekly exposed to subcutaneous injection of EDTA (1 mmol/L). All treatments were completed in a course of 18 weeks and the experiment was finished at week 33.

Results: MTT assay showed selective cytotoxic activity of the cecropins against the human colon adenocarcinoma cells line. The viability of the cancer cells was about 54% and 100% for the normal cells. There was a significantly lower incidence of large intestinal tumors in rats gavaged with cecropins (65%, P<0.01), but the tumor burden (tumors/tumor-bearing animal) and tumor mass index were comparable between the groups (P>0.05).

Conclusion: The cecropins possess effective anti-tumor activity with no cytotoxicity against normal eukaryotic cells, and impede the neoplastic process in murine large intestines.