Abstract:

Objective To investigate the expression of the circular RNA circ-PHC3 in cervical cancer tissues and its regulatory mechanisms in the proliferation， migration， and invasion of cervical cancer cells. Methods The expression levels of circ-PHC3 in cervical cancer tissues and adjacent non-tumor tissues were analyzed using the GEO database. The correlation between circ-PHC3 expression and the clinical stage as well as prognosis of cervical cancer patients was also evaluated. The expression of circ-PHC3 in cervical cancer cell lines HCC94， C33A， HeLa， HCC1106， and SiHa was detected by real-time quantitative polymerase chain reaction （qRT-PCR）. The cell line with the highest circ-PHC3 expression was selected for transfection with a circ-PHC3 inhibitor. The interaction between circ-PHC3 and miR-1179 was validated using a dual luciferase reporter gene assay. The expression levels of miR-1179 in transfected cells were further assessed by qRT-PCR. Functional assays， including colony formation， flow cytometry， wound healing， and Transwell assays， were conducted to evaluate cell proliferation， cell cycle progression， migration， and invasion， respectively. Western blot analysis was performed to determine the expression of key proteins associated with proliferation， migration， and invasion in circ-PHC3-modulated cells. Finally， in vivo experiments were carried out to investigate the impact of circ-PHC3 silencing on the growth and metastasis of cervical cancer cells in animal models. Results The expression level of circ-PHC3 in cervical cancer tissues was significantly higher than that in adjacent normal tissues （P < 0.01）. Furthermore， circ-PHC3 expression was significantly associated with the clinical stage of cervical cancer （P < 0.01）. Patients with high circ-PHC3 expression exhibited a notably lower survival rate compared to those with low circ-PHC3 expression （P < 0.01）. In cervical cancer cell lines including HCC94， C33A， HeLa， HCC1106， and SiHa， circ-PHC3 expression was markedly upregulated （all P < 0.01）， with the highest expression observed in HCC1106 cells （P < 0.01）. Circ-PHC3 was found to directly interact with miR-1179 （P < 0.01）， and silencing circ-PHC3 significantly increased miR-1179 expression （P < 0.01）. Transfection of HCC1106 cells with a circ-PHC3 inhibitor significantly suppressed cell proliferation， migration， and invasion （all P < 0.01）， and induced cell cycle arrest （P < 0.01）； these effects were partially reversed by co-transfection with a miR-1179 inhibitor （all P < 0.05）. In HCC1106 cells with circ-PHC3 knockdown， the expression levels of key proteins associated with proliferation， migration， and invasion—Cyclin E， CDK2， MMP-9， and N-cadherin—were significantly reduced （all P < 0.01）， and this reduction was partially attenuated by miR-1179 inhibition （all P < 0.01）. In vivo experiments further demonstrated that circ-PHC3 knockdown significantly inhibited tumor growth and metastasis of HCC1106 cells （all P < 0.01）. Conclusions Circ-PHC3 is highly expressed in cervical cancer tissues， and its overexpression is significantly correlated with poor prognosis in patients with cervical cancer. Knockdown of circ-PHC3 upregulates the expression of miR-1179 and suppresses the proliferation， migration， and invasion of cervical cancer cells.

Key words: cervical cancer, circ-PHC3, miR-1179, cell proliferation, cell migration, cell invasion