Abstract 2538: Retinol binding protein-1 and E6-E7 HR-HPV mRNA expression in normal cervical tissue and high grade squamous intraepithelial lesions
Authors: Benedetti Ines , Rodríguez Reinhard , Barrios Lia 
Published: July 2021

Abstract
Background: Gene expression differences between cervical healthy tissue and premalignant lesions could contribute to identify potential biomarkers for each step of this tumor progression. In a previous cDNA microarray analysis, we identified the gene Retinol Binding Protein 1 (RBP1), differentially expressed between normal cervix and a high grade squamous intraepithelial lesion (HSIL) with HPV-18 transforming infection. RBP1 codifies a retinol-binding protein implied in differentiation of epithelia and may play a role on inhibition of E2F-dependent gene expression and suppress cell growth.
Design: The expression of RBP1 mRNA was evaluated using RNAscope chromogenic in situ hybridization (CISH) in a tissue microarray constructed from specimens (conization and hysterotomy) obtained from 169 patients, with mean age of 35.37 years (SD ±10.4). Stained sections from donor blocks were reviewed by two pathologist, who chose representative areas of normal cervix, low grade squamous intraepithelial lesion (LSIL), and HSIL. RNAscope 2.5HD Red RBP1 assay, and RNAscope 2.5HD Red HPV-HR18 , that detect E6/E7 mRNA for eighteen different high-risk (HR) HPV genotypes, were performed, the stainings were visually scored by two pathologist from 0 to 4 in a semi-quantitative analysis, based on the average number of red dots per cell. The mean score values for each tissue group were compared using GraphPad Prism® 7.0. A p&lt; 0.05 was considered statistically significant.
Results: The in situ expression of RBP1 mRNA was determined in a cervical TMA including, normal cervix: 66, LSIL: 74, and HSIL: 130, tissue cores. There was not a statistically significant difference (p=0.965) between the RBP1 mRNA expression score in the squamous epithelium from normal cervix (0.42, 95% CI:0.23-0.61), and LSIL (0.51, 95% CI:0.28-0.74). But, its expression was higher in HSIL (1.30, 95% CI:1.09-1.50), with a very significant difference compared to squamous epithelium from normal cervix (p&lt;0.0001). Mean HPV E6/E7 mRNA expression in HSIL was significantly higher than mean HPV E6/E7 mRNA expression in LSIL (p&lt;0.0001). There was positive-moderate correlation between RBP1 mRNA expression and E6/E7 HR-HPV mRNA expression (Spearman r =0.55).
Conclusions: The in situ mRNA expression of RBP1 is similar in LSIL and squamous epithelium lining normal cervix, but the significantly different expression between healthy cervical tissue and HSIL, considered as the real premalignant cervical lesion, confirms our previous findings. There is a moderate correlation with the expression of E6/E7 mRNA for eighteen different HR-HPV. We could hypothesized that this overexpression represent a failed mechanism of regulation induced by the HR-HPV infection in cervical carcinogenesis.
Citation Format: Ines Benedetti, Reinhard Rodríguez, Lia Barrios. Retinol binding protein-1 and E6-E7 HR-HPV mRNA expression in normal cervical tissue and high grade squamous intraepithelial lesions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2538.