RAP1-GTPase immunostaining is altered in human precancerous and cancerous cervical lesions

<b>Aim:</b> This study investigated RAP1 immunostaining variation in different cell types during CC progression. <b>Methods:</b> Paraffin-embedded cervical tissues from 101 patients were categorized into control, pre-neoplastic and neoplastic groups. RAP1 immunolocalization, HPV detection and genotyping were performed. A semiquantitative immunoreactive score was employed to compare labeling intensity, cellular localization, nuclear labeling, percentage and distribution of reactive cells. <b>Results:</b> 73% (72/99) of cervical specimens were HPV+. RAP1 was localized in the nucleus and cytoplasm of all samples. Cytoplasmic RAP1 immunoscore was higher than nuclear score in all CC groups. RAP1 intensity increased with lesion severity. SCC samples exhibited predominantly intense RAP1 immunostaining. <b>Conclusion:</b> RAP1 is an efficient biomarker for detecting invasive CC lesions but has limited utility in distinguishing SCC grades. DNA-HPV search in cervical formalin-fixed and paraffin-embedded (FFPE) tissues detected presence of viral DNA in 73% of cervical specimens. HPV genotyping by automated DNA sequencing determined the prevalence of the HPV types: HPV16 (76%), HPV31 (6.4%), HPV33 (4.8%) and HPV45 (3.2%). RAP1 immunocytochemistry was performed in pre-neoplastic and neoplastic lesions tissues. Evaluation of RAP1 cellular localization detected the protein expression in the nucleus and cytoplasm of all tissue samples. Semi-quantitative analysis of RAP1 labeling intensity in the nucleus reveled that it was stronger in samples from CIN III and SCC groups. Evaluation of distribution of reactive cells in the epithelium thickness. Both histopathological grades of SCC exhibited intense RAP1 labeling observed in 58% of MSCC and 70% of PSCC cases. Only one (14%) sample of the MSCC group (less aggressive) exhibited strong (+3 score) RAP1 nuclear intensity, but 4 (57%) PSCC samples (more aggressive) presented strong nuclear intensity. These data suggest that intensity labeling of RAP1 immunostaining is a good parameter for identifying more severe (CIN III) and invasive cervical lesions.