Nicotine Activates PI3K/AKT Pathway to Induce Cellular Proliferation, Invasion, and Migration in HPV-16 Positive Cervical Cancer SiHa Cells.

Nicotine exerts a substantial influence on cervical carcinogenesis by affecting the malignant progression of human papillomavirus (HPV)-18 positive and HPV-negative cervical cancer cells, as well as HPV-immortalized cervical epithelial cells. Further research is needed to fully elucidate the impact of nicotine on HPV-16 positive cervical cancer. This study investigated the molecular mechanisms of nicotine in HPV-16-positive cervical (SiHa) cells. First, we conducted cell counting kit-8, flow cytometry, wound healing, transwell assays to evaluate cellular proliferation, migration, and invasion capabilities. The data illustrated that nicotine-treated SiHa cells displayed stronger malignant transformation capability compared to the control (p < 0.05). Furthermore, western blot analysis was used to evaluate the expression changes of cellular proteins in SiHa cells. The results revealed that nicotine induces a significant upregulation of PI3K, AKT, phosphorylated AKT (Ser473) (p-AKT), the p-AKT/AKT ratio, and matrix metalloproteinase-2 (MMP-2), along with a marked increase in its secretion. Also, it was accompanied by the suppression of tumor suppressor p53 and decreased levels of p21 and Caspase-3, as well as the active form of Caspase-3 (cleaved Caspase-3), indicating suppression of apoptosis. Critically, the use of a PI3K inhibitor (LY294002) demonstrated that the nicotine-induced downregulation of p53 and upregulation of MMP-2, as well as the enhancement of cellular invasion are dependent on PI3K/AKT pathway activation. These findings conclusively demonstrate that nicotine promotes the malignant transformation of HPV-16 positive cervical cancer cells by altering the expressions of MMP-2, p53, Caspase-3, and p21 via the activation of the PI3K/AKT pathway. This highlights the therapeutic potential of targeting this pathway in cervical cancer treatment.