Infection with certain types of human papillomaviruses (HPV) is highly associated with carcinomas of the human uterine cervix. However, HPV infection alone does not appear to be sufficient for the process of malignant transformation, suggesting the requirement of additional cellular events. After DNA damage, normal mammalian cells exhibit G1 cell-cycle arrest and inhibition of replicative DNA synthesis. This mechanism, which requires wild-type p53, presumably allows cells to undertake DNA repair and avoid the fixation of mutations. We directly tested whether the normal response of cervical epithelial cells to DNA damage may be undermined by interactions between the E6 protein expressed by oncogenic HPV types and wild-type p53. We treated primary keratinocytes with the DNA-damaging agent actinomycin D and demonstrated inhibition of replicative DNA synthesis and a significant increase in p53 protein levels. In contrast, inhibition of DNA synthesis and increases in p53 protein did not occur after actinomycin D treatment of keratinocytes immortalized with HPV16 E6/E7 or in cervical carcinoma cell lines containing HPV16, HPV18, or mutant p53 alone. To test the effects of E6 alone on the cellular response to DNA damage, HPV16 E6 was expressed in the carcinoma cell line RKO, resulting in undetectable baseline levels of p53 protein and loss of the G1 arrest that normally occurs in these cells after DNA damage. These findings demonstrate that oncogenic E6 can disrupt an important cellular response to DNA damage mediated by p53 and may contribute to the subsequent accumulation of genetic changes associated with cervical tumorigenesis.

The cell cycle regulatory tumor suppressor proteins p53 and pRB are targeted for inactivation by several tumor viruses, including the high-risk types of human papillomaviruses (HPVs) via interactions of the HPV E6 and E7 oncoproteins with p53 and pRB, respectively. p53 plays a central role in a signal transduction pathway that mediates G, arrest after DNA damage, though the mechanism by which G, arrest occurs has not been elucidated. The cyclin-associated protein p2lwan/dPl has recently been shown to be induced by

Human papillomavirus (HPV) DNA was identified in the plume produced during CO2 laser vaporization of respiratory tract papillomata. The plume produced from CO2 vaporization was collected on Gelfoam pledgets that were affixed to suction tips evacuating the vapor plume from the operative field. The Gelfoam pledgets were snap frozen in liquid nitrogen, processed, and examined for HPV-6 and HPV-11 DNA by a polymerase chain reaction technique. Tissue and vapor-plume specimens were collected from 22 patients undergoing CO2 laser excision of laryngeal lesions. Seven patients had adult-onset recurrent respiratory laryngeal papillomatosis (RRP), 12 had juvenile-onset RRP, two had laryngeal carcinoma, and one had nonspecific laryngitis. HPV-6 or HPV-11 was identified in 17 of 27 vapor-plume specimens from RRP and in none of three from non-RRP lesions. All but one RRP tissue specimen contained HPV-DNA, and none of the non-RRP tissues contained HPV-DNA. When HPV was present in vapor, the same HPV type was found in the corresponding tissue specimen. Identification of HPV-DNA in the laser plume raises concern regarding potential risks from exposure to the plume--particularly to the endoscopic surgeon and the operating team. The practical concerns and effectiveness of the plume scavenging systems are discussed.

The diagnostic and prognostic relevance of human papillomavirus (HPV) types 6, 11, 16, and 18 in squamous papilloma, inverted papilloma, and squamous carcinoma of the sinonasal epithelium was examined using the polymerase chain reaction (PCR) technique. Four (15%) of 26 squamous papillomas, 7 (24%) of 29 inverted papillomas, and 1 (4%) of 24 squamous carcinomas were positive for HPV when examined using the PCR amplification technique. Human papillomavirus 6 was present in 5 specimens (3 squamous and 2 inverted papillomas); HPV-11 was present in 6 specimens (1 squamous and 5 inverted papillomas); and HPV-18 was present in 1 of 24 squamous carcinomas. HPV-16 was not identified in any specimen. The proportion of tissue samples showing HPV presence, and the association of HPV types 6 and 11 with benign lesions and HPV-18 with malignant lesions, are both in accord with findings from prior investigations. Two major questions regarding nasal papilloma are the probability for lesion recurrence after surgical excision and the risk for malignant transformation. There is no unanimity of opinion regarding the prognostic value of histopathologic dysplasia to forecast these outcomes. HPV is etiologically related to a subset of sinonasal papillomas and squamous carcinoma, and those with benign and malignant clinical course are separable on basis of HPV type. Because of the paucity of these nasal lesions, a multi-institutional prospective collaborative study is the ideal way to address these questions.

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Clinical and epidemiological studies have implicated the involvement of human papillomavirus (HPV) infection in cervical tumorigenesis. We have previously shown that expression of high-risk (HPV16) E6 can abrogate an important cell cycle checkpoint mediated by p53. Sublethal DNA damage causes p53 accumulation and G1 arrest in normal cells, but not in cells with mutant or absent p53, or in cells that express HPV16-E6. To investigate the functional consequences of low-risk (HPV11) E6 expression and to evaluate regions of E6 believed to mediate interaction with p53, we generated several E6 expression constructs, including HPV11-E6, and fourdifferent E6 mutants. HPV16E6 deltaD and HPV16E6 deltaB had short deletions of nucleotides encoding amino acids previously implicated in p53 degradation and binding, respectively. HPV16E6HL and HPV11E6LH had the putative p53 binding domain exchanged between the high- and the low-risk types. Unlike HPV16-E6, HPV11-E6 and the mutant E6 proteins were not able to bind or degrade p53 in in vitro assays. When expressed in RKO cells, HPV11-E6 or the mutant E6 proteins did not prevent p53 accumulation or interfere with p53-dependent WAF1/CIP1 mRNA expression, allowing p53-mediated G, cell cycle arrest after DNA damage. These findings demonstrate that low-risk and high-risk E6 proteins differ in their effects on p53-mediated cell cycle control and that rather subtle mutations of high-risk E6 can alter its ability to abrogate this important cellular response.

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