Expression and splicing patterns of human papillomavirus type‐16 mrnas in pre‐cancerous lesions and carcinomas of the cervix, in human keratinocytes immortalized by HPV 16, and in cell lines established from cervical cancers

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Abstract
We have analysed the splicing patterns of human papillomavirus (HPV) type‐16 mRNAs in a human epithelial cell line immortalized by HPV 16 (HPKII), in cell lines established from cervical carcinomas (SiHa and CaSki) and in pre‐invasive and invasive carcinomas of the cervix. The presence of mRNA species previously described, which could encode the E6, E6I, E6II, E6III, E7, E2, E2C, E4, E5 and L1 proteins, was determined, using the RNA polymerase chain reaction (PCR) technique with primers that flank unique splice sites. The state of the viral DNA in the tumor biopsies was established by Southern blot analysis. The various HPV 16 transcripts could be detected in cell lines and in tumor biopsies. The size of the RNA PCR products were in agreement with the previously mapped splice sites. The full range of transcripts was revealed in the HPKII cell line and in a number of pre‐invasive carcinomas. Messenger RNAs which could encode the E6III, E4 and E5 proteins were most prevalent in all types of tumor. The overall results of DNA and RNA analyses in cell lines and tumor specimens indicate that (1) expression of either of the early or late transcripts studied is not specifically related to (a) tumor stage or (b) the physical state of the viral genome; and (2) alterations in the splicing patterns of HPV 16 transcripts may not be involved in tumor progression.