Cytotoxic activity and mechanism of action of Smp43 scorpion peptide against colorectal cancer cell line HCT-116

Abstract

This study was conducted to extend our previous investigations to examine the cytotoxic efficacy of Smp43 scorpion peptide against colorectal cancer cell line (HCT-116) and revealing its molecular mechanisms of action. Using MTT assay, Smp43 significantly induced cytotoxic effects on HCT-116 cancer cells compared to normal colon epithelial cell line (FHC) of IC50 4.11 and 62.17 µg/ml, respectively. Flow cytometric apoptosis assay showed that IC₅₀ (4.11 µg/ml) of Smp43 induced a remarkable increase in the proportion of HCT-116 cancer cells undergoing late apoptotic cell death. Also, Smp43 caused cell cycle arrest at the S phase. RT-PCR analysis showed highly significant downregulation of Bcl-2 anti-apoptotic gene and ki-67 proliferative markers in HCT-116 treated with IC50 of Smp43. In contrast, caspase-3, −8, −9, Bax, and p53 apoptotic genes were upregulated. Protein expression levels of caspase-3, −8, −9, and p53 were similarly elevated in treated cells using a western blot analysis. The apoptotic characteristics were also confirmed through scanning and transmission electron microscopy. The Smp43 treated HCT-116 cancer cells showed cell membrane blebbing, pore formation, heterochromatin condensation toward the nuclear envelope, leakage of cell organelles, and formation of apoptotic bodies. Consequently, Smp43 peptide provides a great starting point for creating effective cytotoxic agents against human colorectal cancer.

Keywords:

• Smp43
• Scorpion venom peptide
• Scorpio maurus palmatus
• colorectal cancer
• apoptosis
• cell cycle analysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, [Mohamed A. Abdel-Rahman], upon reasonable request.

Additional information

Funding

This paper was based upon work supported by the Science, Technology & Innovation Funding Authority (STDF; Egypt) under grant number 45890 awarded to Mohamed A. Abdel-Rahman and National Science Academy (USA) awarded to Prashant P. Sharma, U.S. - Egypt Science and Technology Joint Fund.