Exploring the effects of alpha-pinene on apoptosis induction in human colon cancer cells via the PI3K/AKT signaling pathway: an in vitro study

Abstract

Background: Colorectal carcinoma ranks as the second most prevalent neoplasm in females and the third most prevalent in males. Methods: In this investigation, we examined the influence of alpha-pinene (ALP), classified as a monoterpene, on the proliferation of HT-29 human colorectal carcinoma cells via the PI3K/AKT signaling cascade. HT-29 cells were exposed to a range of ALP concentrations. The survival rate of the cells was assessed through the MTT assay; while, apoptotic events were evaluated using flow cytometry in conjunction with Annexin V/PI staining. Additionally, cell cycle dynamics were scrutinized through fluorescence-activated cell sorting. The expression levels of Bax, Bcl-2, Caspase-3, PI3K, and AKT at both the gene and protein levels were quantified employing real-time PCR and western blot techniques. Results: ALP treatment led to a significant, dose-dependent decrease in cell viability, with prolonged exposure exacerbating cytotoxic effects. Apoptosis analysis showed that ALP significantly increased apoptotic cells after 24 h of treatment. Cell cycle analysis showed that ALP induces G2/M phase arrest and inhibits cell proliferation and DNA synthesis. Gene expression analysis revealed upregulation of pro-apoptotic genes Bax and caspase-3 and decreased anti-apoptotic gene Bcl-2. Furthermore, the administration of ALP led to a notable reduction in both the gene and protein expression levels of PI3K and Akt, suggesting a suppression of the PI3K/Akt signaling cascade. Conclusion: ALP inhibits HT-29 colon cancer cell growth by reducing cell viability, inducing apoptosis, and blocking the PI3K/AKT pathway. These findings highlight ALP’s potential as a therapeutic candidate for colorectal cancer.