PIWIL2/PDK1 Axis Promotes the Progression of Cervical Epithelial Lesions via Metabolic Reprogramming to Maintain Tumor-Initiating Cell Stemness.

When PIWIL2 expression is restored via heterogeneous integration of human papillomavirus, cellular reprogramming is initiated to form tumor-initiating cells (TICs), which triggers cervical squamous intraepithelial lesions (SIL). TIC stemness is critical for the prognosis of SIL. However, the mechanisms underlying TIC stemness maintenance and tumorigenicity remain unclear. Here, it is revealed that aberrant pyruvate dehydrogenase kinase 1 (PDK1) expression is closely related to aerobic glycolysis in SIL and poor survival in patients with cervical cancer. Mechanistically, that PIWIL2, which induced by stable transfection of either PIWIL2 or HPV16 oncogene E6 in human primary cervical basal epithelial cells and keratinocyte cell line HaCaT, upregulates PDK1 expression via the LIN28/let-7 axis, hence reprogramming metabolism to activate glycolysis and synchronize with TIC formation. It is further demonstrate that PDK1 is critical for TIC stemness maintenance and tumorigenicity via the PI3K/AKT/mTOR pathway both in vitro and in vivo, revealing a previously unclear mechanism for SIL progression, regression or relapse. Therefore, this findings suggest a potential rationale for prognostic predictions and selecting targeted therapy for cervical lesions.