Abstract 2955: HPV E6* and senescence-related gene expression in cervical cancer
Authors: Bengtsson Louise Medina , Inkman Matthew , Muhammad Naoshad , Castillo Leahan , Msengi Naomi , McKinnish Tyler , Gabriel Nishanth , Zhang Jin , Schwarz Julie 
Published: March 2024

Abstract
Previous work in our lab found that increased expression of the E6* variant of the HPV E6 viral protein was significantly correlated with worse response to standard-of-care chemoradiation (CRT) and progression-free survival, independently of HPV genotype. In vitro validation showed that overexpression of E6* induces senescence in an HPV 16-positive cervical cancer cell line. Given these findings, we hypothesized that increased E6* expression mediates resistance to CRT by inducing a reversible state of tumor cell senescence. We created a senescence score using ten genes that have been consistently reported in the literature as associated with senescence. Using an institutional cohort of 68 patients with cervical cancer with prospectively collected clinical outcome data, we performed bulk RNA sequencing to assess senescence scores before CRT and determine whether there is an association between senescence scores and E6* expression. Using a second institutional cohort of 35 patients with cervical cancer treated with CRT with pre and posttreatment tumor biopsies, we performed bulk RNA sequencing to evaluate the same relationship and determine whether expression of senescence-related genes was affected by CRT. Nine cervical cancer cell lines stratified into low- and high-E6* expression groups will be assessed regarding their senescence score, beta-galactosidase staining, and SASP expression before and after CRT. In our first cohort, there was no correlation between E6*:E6 expression ratio and senescence score, regardless of HPV genotype. In our second cohort, CRT increased senescence score in CRT-treated samples (p &lt; 0.01), but p16INK4a expression significantly decreased compared to pre-treatment samples (p &lt; 0.01). Increased senescence score was not associated with cancer recurrence. There was no significant difference in senescence scores between different HPV genotypes before therapy. Tumors that were positive for HPV 16 or HPV 18 had significantly lower senescence scores compared to HPV negative tumors (p = 0.037 and p = 0.038, respectively) after CRT. Among HPV 16-positive tumors (n = 12), there was no correlation between E6*:E6 expression ratio and senescence score before or after CRT. We found no association between senescence score and E6* expression, and between senescence score and cancer recurrence after CRT in our dataset. Additionally, our results suggest that p16INK4a might not be an appropriate senescence marker in tumors that have intrinsically high p16INK4a expression, such as in cervical cancer, reinforcing the need for a cervical cancer-specific senescence signature. We are currently testing beta-galactosidase and SASP expression in vitro and in vivo before and after CRT.
Citation Format: Louise Medina Bengtsson, Matthew Inkman, Naoshad Muhammad, Leahan Castillo, Naomi Msengi, Tyler McKinnish, Nishanth Gabriel, Jin Zhang, Julie Schwarz. HPV E6* and senescence-related gene expression in cervical cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2955.