‘Nelfinavir sensitizes a clinically relevant chemo-radioresistant cervical cancer in-vitro model by targeting the AKT-USP15/USP11-HPV16 E6/E7 axis

Resistance to standard therapies is a major challenge in managing cervical cancer, often leading to systemic relapse. This study aimed to develop an <i>in-vitro</i> model of chemo-radioresistant cervical cancer that mimics clinical conditions and also explore the therapeutic potential of the repurposed drug nelfinavir, an HIV protease inhibitor. HPV16-positive SiHa cervical cancer cells were subjected to concurrent cisplatin and ionizing radiation, to simulate the clinical treatment regimen for locally advanced cervical cancer. The resulting chemo-radioresistant subline exhibited increased IC₅₀-value, D0 dose, and a higher Resistance Index compared to parent cells, indicating resistance development. Notably, elevated HPV16 E6/E7 expression in resistant sublines suggested a role for HPV16 in resistance acquisition. Treatment with nelfinavir significantly reduced the IC₅₀-value and D0 dose in resistant cells. Additionally, exposure to nelfinavir or AKT inhibitor IV showed significant decrease in AKT, USP15, USP11 and HPV16 E6/E7 proteins. Furthermore, siRNA mediated knockdown of USP15 and USP11 in resistant cells resulted in significant reduction of HPV16 E6 and E7 oncoproteins respectively. Thus, mechanistically nelfinavir sensitized resistant cervical cancer cells by inhibiting the AKT-USP15/USP11-HPV16 E6/E7 pathway. Overall, this study successfully established a chemo-radioresistant SiHa cell model, providing a platform for investigating resistance mechanisms. It also highlights nelfinavir's potential as a therapeutic agent in overcoming chemo-radioresistance in cervical cancer.