Designing a Temporin-1CEa Analog with Improved in Vitro Selectivity towards Prostate Cancerous Cell Line (LNCaP)

Abstract

Temporins are small antimicrobial peptides which have cytotoxic effects against different cancerous cell lines. However, their cytotoxicity against normal cells has been reported in some studies. Designing new temporin analogs with selective cytotoxicity against cancerous cell lines is considered a goal in drug development. In this regard, four new temporin-1CEa analogs (either C-terminally α-amidated or not) with increased net positive charge, as well as the potential of hydrogen bond formation were designed and their selective cytotoxicity against prostate carcinoma cell line (LNCaP) was evaluated. MTT assay was employed to test the simultaneous effects of the modifications on the cytotoxicity of the analogs against both normal (HFFF₂) and cancerous (LNCaP) cell lines. Then, the in vitro selectivity index of each analog was determined using the equation of selectivity index (SI= IC₅₀ of peptide against normal cell line / IC₅₀ of peptide against cancerous cell line). The structural modifications of temporin-1CEa (increasing the net positive charge and removing C-terminally amidated group, as well as the potential of hydrogen bond formation on the non-polar face of α-helical structure) reduced the cytotoxicity of K₂K₃W₁₅-COOH analog against both cancerous (LNCaP) and normal (HFFF₂) cell lines. However, the modifications resulted in improving the in vitro selectivity index of K₂K₃W₁₅-COOH compared to the temporin-1CEa (1.67 vs. 1.33, respectively). The results of the present study indicated that some structural modifications may lead to a diminution in the cytotoxicity of new analogs against cancerous cells. However, the same modifications can be associated with better selectivity indexes of new analogs due to a further decrease in their cytotoxicity against normal cells.