ABSTRACT
To study the gene variation and the distribution of HPV16 variant in Hubei, China, DNA was extracted from cervical cancer tissue samples. The E6 and E7 genes of HPV16 were amplified and the PCR products were sequenced using E6- and E7-specific primers. Fortyseven cases were found mutations at nucleotide position 178 of HPV16 E6 gene in 80 cervical cancer samples. This mutation resulted in amino acid change from Asp to Glu. The rate of mutation at nucleotide position 178 of E6 gene was 58. 75%. Twenty two cases were found mutations at nucleotide position 647 of HPV16 E7 gene in 31 cervical cancer samples. This mutation resulted in amino acid change from Asn to Ser. The rate of mutation was 70.97%. These results showed that mutations at nucleotide position 178 of E6 gene, nucleotide position 647 of E7 gene of HPV16 in cerveical cancer samples were prevalent in Hubei, China. Phylogenetic analysis showed that Asian (As) variants of HPV16 are predominated in Hubei, China. European (Ep) varinats were also found in Samples in Hubei areas. None of Asian American (AA), African-1 (Af-1), African-2 (Af-2) variants of HPV16 was found in this region. Whether Asian (As) variants of HPV16 are more oncogenic and play a much more important role in the progress of cervical cancer than European (Ep) variants is not clear. More sequences of E6 and E7 gene in CIN and normal cervical tissue samples and study of the function of E6 and E7 protein of these HPV16 variants are needed to adress above question.
Subject(s)
Adult , Female , Humans , Middle Aged , China , Evolution, Molecular , Mutation , Oncogene Proteins, Viral , Chemistry , Classification , Papillomavirus E7 Proteins , Classification , Genetics , Phylogeny , Polymerase Chain Reaction , Repressor Proteins , Chemistry , Classification , Uterine Cervical Neoplasms , VirologyABSTRACT
<p><b>OBJECTIVE</b>The aim of this study was to analyze the relative distribution and gene variation of HPV16 transforming gene E6, E7 and E5 at different stages of cervical lesions.</p><p><b>METHODS</b>DNA was extracted from tissue samples of 200 patients with cervical lesions, including 124 cervical cancer, 17 CIN grade I and II, 23 CIN grade III and 36 cervicitis. Then HPV16 E6, E7 and E5 genes were amplified, and part of the E6 and E7 PCR products were sequenced using the HPV16 E6 and E7 specific primers.</p><p><b>RESULTS</b>The positive rate of E6 gene in cervicitis, CINI and CINII, CINIII and cervical cancer was 25.0%, 29.4%, 60.9% and 76.6%, respectively. The positive rate of E7 gene was 16.7%, 41.2%, 43.5% and 61.3%, respectively. The positive rate of E5 gene was 5.6%, 5.9%, 30.4% and 40.3%, respectively. HPV16 E6 gene mutations in Nt 178 were found in 47 case from 80 cervical cancer samples, resulting in amino acid change of Asp to Glu. The mutation rate was 58.8%.Otherwise the mutation rate of E6 178 in cervicitis and CIN I approximately III samples was 25.0% and 31.8%. E7 mutations were found in Nt 647 in 21 cervical samples from 30 cervical cancer samples, resulting in amino acid change of Asn to Ser. The mutation rate was 70.0%. The mutation rate of E6 647 in cervicitis and CINI approximately III samples was 35.0% and 40.9%, respectively.</p><p><b>CONCLUSION</b>The positive rate of E6 and E7 increase gradually from cervicitis, CINI and CINII, CINIII to cervical cancer. The rate of E5 is relatively lower than that of E6 and E7 gene in cervical tissue samples. These results show that E6 and E7 gene are highly associated with the progress of cervical cancer and E5 genes are lost in the development of cervical cancer. High frequency mutations of HPV16 E6 and E7 gene in E6 178, E7 647 have been found in cervical cancer samples in Hubei province, China. These results approved that the HPV16 variants prevalent in this area are different from the European and African variants.</p>