Polymorphisms and functional analysis of the intact human papillomavirus16 e2 gene

Integration sites of human papillomavirus 18 in esophageal cancer samples

To investigate the association between human papillomavirus (HPV) infection and esophageal cancer, genomic DNA was isolated from 189 samples obtained from patients with esophageal carcinoma, and HPV DNA was identified using the polymerase chain reaction (PCR) with the following specific primers: My09/11 for HPV L1 and HPV18 E6 for HPV18. The HPV18 gene products were sequenced to identify the HPV genotype and the HPV18 integration site was verified using PCR amplification of papillomavirus oncogene transcripts. HPV18 oncogene transcript products were ligated into a pMD-18T plasmid vector and sequenced to confirm the physical location of HPV18 integration. Of the 189 samples, 168 were positive for HPV, of which 33 were positive for HPV18. The sequencing analysis identified two HPV18 E6-positive samples containing one mutation and two samples containing two mutations in the viral DNA. In total ~600 bp of the HPV18 oncogene transcript was detected in three esophageal cancer samples. Sequence analysis revealed that, in two patients, the HPV18 infection was integrated into human chromosome 5, whereas in the remaining sample the virus was integrated into human chromosome 2. The high prevalence of HPV18 infection suggested that HPV18 infection is a pathogenic factor in esophageal carcinoma progression. The integration of HPV18 DNA into the host cell genome suggests that persistent HPV infection has a role in esophageal epithelial cell malignant transformation and carcinogenesis.

Integration of human papillomavirus 16 in esophageal carcinoma samples

Background

Esophageal carcinoma (EC) is one of the major cancers in China. In 1982, Syrjanen first hypothesized the relationship between human papillomavirus (HPV) infection and the development of esophageal cancer. Since then, many reports in the field have supported this viewpoint. This study investigated the etiological relationship between HPV infection and the occurrence of esophageal carcinoma at Tangshan City of the Hebei province in China.

Methods

189 samples of esophageal carcinoma patients were collected. DNA and RNA were isolated from samples, HPV DNA was detected by polymerase chain reaction (PCR) using My09/11 for HPV L1, and HPV16 was determined using type-specific primer sets for HPV16 E6. The HPV16 integration site was verified by amplification of papillomavirus oncogene transcripts, and HPV16 oncogene transcript products were ligated to the pMD-18 T vector and sequenced to confirm the physical location of HPV16 integration.

Results

168 HPV-positive samples were detected in 189 samples, and among them 76 specimens were HPV16 positive. Approximately 600 bp of the HPV16 oncogene transcript were detected in nine esophageal cancer samples. Sequence analysis revealed that HPV16 E7 integrated into human chromosome 2 in three samples, into human chromosome 5 in one sample, into human chromosome 6 in one sample, into human chromosome 8 in two samples, and into human chromosome 17 in two samples. The results verified that the integrated HPV16 E7 in five samples harbored one mutation of viral DNA compared with the HPV16 sequence provided in GenBank (K02718).

Conclusions

The high prevalence of HPV16 suggests that HPV16 may play an etiological role in the development of esophageal cancer. The integration of HPV16 into host cell chromosomes suggests that persistent HPV infection is key for esophageal epithelial cell malignant transformation and carcinogenesis.