HPV16-E6/E7 Oncogene Mutation and p53 Expression among Indonesian Women with Cervical Cancer

Abstract

Objective: To characterize HPV16 E6/E7 mutation and its association with p53 expression among Indonesian women with cervical cancer. Methods: This is a cross-sectional study involving 31 Indonesian women with pathologically proven cervical cancer and HPV16 infection. Data about the clinical characteristics of the study population were obtained from the medical records. Biopsy specimen of the cervical cancer mass from each study participant was obtained for DNA isolation. The ORFs of E6 and E7 genes were amplified using specific primer designed according to K02718/HPV16R gene sequence obtained from GenBank. Sequencing was performed using software program MEGA10. HPV16 E6 and E7 prototype sequences for nucleotide alignment (HPv16. P, GenBank Access code: NC_001526) was selected from European variant. The sequence of nucleotide and amino acid was aligned using software program BioEdit. p53 expression was evaluated through immunohistochemistry and quantified using immunoreactivity score (IRS). Results: Twelve subjects (38.7%) present with E6 and E7 mutation. Median age, parity, stage and histologic type of the tumour did not associate with E6/E7 mutation. E6 and E7 mutation rate was 25.8% (8/31) and 12.9% (4/31), respectively. Seven single nucleotide changes were identified within the E6 and E7 oncogenes, including four non-synonymous and three synonymous mutations. E6 T27C was the most prevalent mutation (16.1%). Nonsynonymous mutations were more prevalent within E7 gene (9.6%) (N29T, N29S, and R77C). Median IRS did not differ between HPV16-E6/E7 variants and wildtype (p value = 0.990). There was no association between E6/E7 mutations and p53 expression in Indonesian women with cervical cancer (PR 1.4, 95% CI: 0.29-6.77, p value = 0.704). Conclusions: HPV16 E6 mutation was more prevalent than E7 mutation among Indonesian women. There was no association between E6/E7 mutation and p53 expression level.

The difference of transcriptome of HPV-infected patients contributes more to the occurrence of cervical cancer than the mutations of E6 and E7 genes in HPV16

“…[35,36] Another study found no correlation of HPV16 E6 and E7 gene mutations with the expression level of tumor suppressor p53 in Indonesian women. [24] Moreover, EP[a], the most common variant identified in a clinical study of 10,000 women in Costa Rica, also showed no association with CxCa. [25] In this study, T178G/A, T350G, A131C, and T241G were the most frequent mutations of HPV16 E6 gene.…”

“…However, these are related to the occurrence of immune-related events, which is consistent with the previous studies mentioned above. [24,25,35,36] The KEGG enrichment analysis of DEGs between CxCa group and non- CxCa group showed that these DEGs were enriched in MAPK signaling pathway. This indicates that the occurrence of CxCa may be related to the activation of MAPK signaling pathway, which is also consistent with a previous study that implicated the MAPK signaling pathway in the development of CxCa.…”

“…[21][22][23] However, in a study conducted in Indonesian women, HPV16 E6 and E7 gene mutations showed no correlation with the expression level of tumor suppressor p53. [24] In addition, EP[a], the most common variant found in a large clinical study of 10,000 women in Costa Rica, also showed no association with CxCa. [25] To summarize, HPV16 infection and its own gene mutations are closely related to the occurrence and development of CxCa, but there is no clear consensus on the correlation of E6 and E7 gene mutations with the occurrence and development of CxCa.…”

“…[21–23] However, in a study conducted in Indonesian women, HPV16 E6 and E7 gene mutations showed no correlation with the expression level of tumor suppressor p53. [24] In addition, EP[a], the most common variant found in a large clinical study of 10,000 women in Costa Rica, also showed no association with CxCa. [25]…”