Splicing Factor PTBP1 Silencing Induces Apoptosis of Human Cervical Cancer Cells via PI3K/AKT Pathway and Autophagy

Cervical cancer is the most common gynecological malignancy in the world and seriously threatens to women's lives and health. Polypyrimidine tract binding protein 1 (PTBP1), as an important splicing factor, has been identified as a proto-oncogene in several cancers, but its role and mechanism in cervical cancer remain poorly understood. Thus, our aim is to explore the impact of PTBP1 on proliferation, migration, apoptosis of cervical cancer cells, and its underlying mechanisms. The biological functions in cervical cancer cells were determined using small interfering RNA (siRNA), agonist, Cell Counting Kit-8 (CCK-8), transwell, migration test, western blot, real-time-PCR, immunohistochemistry and immunofluorescence, respectively. The results indicated that PTBP1 was highly expressed in cervical cancer patients and cervical cancer cell lines compared to the normal group. Moreover, PTBP1 silencing significantly inhibited cell proliferation, and migration in both HeLa and SiHa cells. The PTBP1 silencing also induced mitochondrial apoptosis through upregulating Bax and mitochondrial apoptotic protein Cytochrome C, and downregulating B-Cell Leukemia/Lymphoma 2 (Bcl2) protein. Additionally, PTBP1 silencing induced autophagy by downregulating Sequestosome I (p62) and upregulating the ratio of Light chain 3-Ⅱ/Light chain 3-Ⅰ (LC3-Ⅱ/LC3-Ⅰ). Mechanistically, we found that the Phosphoinositide 3-kinase (PI3K) agonist reversed the changes induced by PTBP1 silencing. Overall, PTBP1 silencing can induce cervical cancer cells apoptosis mainly through PI3K/AKT pathway and protective autophagy. This study provides preliminary evidence for PTBP1 as a therapeutic target or prognostic marker for cervical cancer.