Relationship of stable integration of herpes simplex virus-2 BglII N subfragmentXho2 to malignant transformation of human papillomavirus-immortalized cervical keratinocytes

Transfection of the right end Xho2 subfragment of BglII N of herpes simplex virus-2 (HSV-2) into human genital keratinocytes immortalized by human papillomavirus (HPV) type 16 or 18 resulted in invasive and noninvasive indolent cystic squamous carcinomas when cells were injected into immunocompromised mice. Retention and expression of the right end portion of the BglII N fragment correlated with malignancy, as the corresponding HSV-2 sequences were integrated and transcribed in the tumorigenic cell lines. HPV-immortalized cells alone were not tumorigenic. In contrast, previous results have shown that using the entire BglII N region can malignantly transform HPV-immortalized cells, although HSV2 DNA was not retained. Together, these observations localize the transforming activity of BglII N to Xho2 and suggest that the remaining sequences have an inhibitory effect on stable integration. The Xho2 sequence is 2480 bp long and contains an open reading frame (ORF) extending from nucleotides 559 to 1797. The ORF encodes a putative protein of 412-aa with a m.w. of 42–43 kDa and is highly homologous to U_L43 of HSV-1. The correlation of tumorigenicity with stable integration and expression of Xho2 DNA in HPV-immortalized cells indicates that HSV-2 should be investigated further for a possible role in cervical cancer. Int. J. Cancer 76:865–871, 1998.© 1998 Wiley-Liss, Inc.+ This article is a US Government work and, as such, is in the public domain in the United States of America.