Induction of Apoptosis with Cyrtopodion Scabrum Extract in Colon Cancer Cells: A Preliminary Study on Targeting P۵۳ Signaling Pathway

Background: Cyrtopodion scabrum is a kind of lizard, widely distributed in southwestern, central, and eastern Iran. In our previous studies, we showed the selective anticancer properties of Cyrtopodion scabrum extract (CSE) against certain gastrointestinal cancer cell lines with no significant harmful effects on the normal cells. Method: This in vitro study was conducted to investigate the mechanism of action of CSE in SW۷۴۲ (colon cancer cell line) using western blotting, real-time polymerase chain reaction (PCR), and PI staining/flow cytometry analysis. Results: Western blot analysis showed that CSE upregulates P۵۳ protein expression significantly in SW۷۴۲ cancer cell line, while QRT-PCR results revealed that P۵۳ mRNA did not increase accordingly. It is proposed that TP۵۳ protein play its role as a tumor suppressor through the protein stability mechanism and not through the increase in the gene expression. Considering this fact, for TP۵۳ stabilization, two of its target genes, p۲۱ and mdm۲, were regulated. We evaluated the mRNA expression of these two genes as well. The obtained data showed a significant increase in both genes by CSE (۱۰۰۰ μg/ml), suggesting that the induction of G۲ cell cycle arrest, which we previously reported, may happen through P۵۳ and P۲۱over-expression. No significant decrease was observed in apoptosis when SW۷۴۲ cells were co-treated with CSE and the inhibitor of P۵۳ transcriptional activity, (PFT)-α, indicating that the induction of apoptosis with CSE did not occur through P۵۳-dependent transcriptional activity. Conclusion: The obtained results herein revealed that the observed anticancer effect of CSE may occur through TP۵۳ upregulation, yet with P۵۳-independent transcriptional activity.

Keywords:

Natural anticancer product , Gecko (Gekko) extract , Cyrtopodion scabrum , Western blot analysis , Real-time PCR , Flow cytometry , P۵۳ signaling pathway