Human papillomavirus16 E7 enhances cell stemness by regulating the APC2/SPIN4/β-catenin axis in cervical cancer

High-risk human papillomavirus (HPV) is a causal factor in cervical cancer, driving the cancer's initiation and progression. Although cancer stem cells (CSCs) have been implicated in maintaining the stemness and malignancy of cervical cancer cells, the underlying mechanisms are not yet fully understood. In this study, we modulated gene expression in Caski and SiHa cervical cancer cells using siRNA and overexpression approaches. Functional assays, including MTT, transwell, RT-qPCR, western blotting, immunohistochemistry, luciferase reporter, immunofluorescence, and sphere formation, were performed to evaluate target gene expression. Additionally, transcriptome sequencing was used to analyze the impact of silencing HPV16 E7 on SiHa cells, and a xenograft model was assessed for in vivo effects. Our transcriptome sequencing reveals substantial changes in gene expression profiles upon HPV16 E7 silencing in cervical cancer. Notably, we identified APC2 as a key downstream target transcriptionally activated by HPV16 E7 through the transcription factor E2F1, and its elevated expression is associated with poor prognosis in cervical cancer. Surprisingly, APC2 exhibits oncogeneic properties in cervical cancer by activating the Wnt/β-catenin pathway, and its overexpression reverses the inhibitory effects of HPV16 E7 silencing on malignancy and CSC properties. Additionally, SPIN4 is identified as a pivotal downstream target of the HPV16 E7/APC2 axis, positively modulating cervical cancer progression. Our study reveals a novel HPV16 E7-APC2-SPIN4 axis as a key driver of cervical cancer. In this pathway, APC2 unexpectedly functions as an oncogene by activating the Wnt/β-catenin signaling to promote tumorigenesis and CSC properties.