The expression analysis of human endogenous retrovirus-K Env, Np9, and Rec transcripts in cervical cancer

While infection with high-risk human papillomavirus (HPV) types is necessary for cervical cancer (CC) development, it is not enough, and other risk factors are required. Several studies have reported the activation of HERV-K in different cancers; however, the investigation of HERV-K expression levels in CC is scarce. In this study, it was hypothesized that activation of HERV-K could play an essential role in CC development. In this order, the expression levels of HERV-K Env, Np9, and Rec transcripts were investigated on 147 normal to CC uterine cervical tissues using quantitative real-time PCR. The significantly higher levels of HERV-K Env and Np9 transcripts were found in patients with cervical intraepithelial neoplasia (CIN) II-III and CC groups compared to those in the normal/CIN I group. Expression of Rec transcript was also higher only in the CC group than normal/CIN I group. Among CC patients, meaningfully higher levels of HERV-K Env and Np9 transcripts were found in patients with squamous cell carcinoma rather than in adenocarcinoma. When only the HPV 16 positive samples were investigated, it was found that the mean difference in Env and Np9 mRNA levels was meaningfully higher among precancer lesions and the cancer group in comparison with the normal group. However, the Rec mRNA level showed no significant differences. The association between the expression of HERV-K genes was investigated, and a significant positive correlation of Env expression with Np9 transcript was found only in the group with precancer lesions (R = 0.6, p = 0.0037). Moreover, a significant positive correlation was found between Rec and Np9 transcripts in patients with normal cervix tissues (R = 0.26, p = 0.033). However, no correlations were observed between the expression of Env and Rec in the three groups. In conclusion, our results showed that HERV-K transcripts, especially Env and Np9, upregulated during cervical lesion progression. These findings highlight the potential use of HERV-K Env and Np9 as biomarkers for CC diagnosis and prognosis. Further investigation is needed to determine the clinical utility of these markers and whether targeting HERV-K oncogenes could be a viable therapeutic strategy for CC.