Targeting the interplay between human papillomavirus oncoproteins and hedgehog signaling: assessment of chemopreventive potential of carvacrol in cervical cancer.

Abstract

Cervical carcinoma is the fourth most frequently diagnosed cancer and is a serious cause of increased mortality among females globally. Hedgehog/GLI signaling has now been established to play a pivotal role in imparting tumor recurrence and promoting metastasis in cervical carcinoma. HPV associated oncoproteins particularly E6/E7 concomitantly with altered signaling pathways are key determinants of cervical cancer. Nevertheless, the nexus between HPV oncogenes and Hedgehog/GLI signaling till date remains unclear. In this study, we investigated the anticancer and apoptotic potential of carvacrol against cervical cancer cells in vitro by targeting the plausible nexus between HPV oncoproteins and Hedgehog signaling. The findings from cell proliferation, LDH cytotoxicity, and morphology analysis suggested that carvacrol treatment significantly decreased the number of viable CaSki cells in a concentration and time-related manner. Morphological trademarks of cell death, including fragmentation of CaSki cell nucleus were studied by DAPI/PI and Hoechst33342 staining. The cytotoxicity of carvacrol was mediated through apoptosis, as confirmed by the Annexin V/FITC assay and caspase activation. Cell cycle analysis showed that carvacrol exerted significant impeding effects on the proliferation of CaSki cells via G₀/G₁ arrest. Intriguingly, carvacrol mediated the downregulation of HPV E6 and E7 oncogenes indicated its plausible role as an anti-HPV agent against HPV16⁺ CaSki cells. Additionally, carvacrol further restored p53 expression implicating that carvacrol may protect E6 mediated p53 protein degradation in CaSki cells. Thus, carvacrol exhibited strong antiproliferative potential by inducing apoptosis in cervical carcinoma cells via mediating the crosstalk between the downregulation of HPV oncogenes and inhibition of the hedgehog signaling pathway.