The E6 oncoprotein derived from tumour-associated human papillomaviruses (HPVs) binds to and induces the degradation of the cellular tumour-suppressor protein p53. A common polymorphism that occurs in the p53 amino-acid sequence results in the presence of either a proline or an arginine at position 72. The effect of this polymorphism on the susceptibility of p53 to E6-mediated degradation has been investigated and the arginine form of p53 was found to be significantly more susceptible than the proline form. Moreover, allelic analysis of patients with HPV-associated tumours revealed a striking overrepresentation of homozygous arginine-72 p53 compared with the normal population, which indicated that individuals homozygous for arginine 72 are about seven times more susceptible to HPV-associated tumorigenesis than heterozygotes. The arginine-encoding allele therefore represents a significant risk factor in the development of HPV-associated cancers.

Ultraviolet B (UVB) damage is recognized as the most important etiological factor in the development of skin cancer. Human papillomaviruses (HPV) have also been implicated in the disease, although the mechanism of action of these viruses remains unknown. We present evidence here that Bak protein is involved in signaling apoptosis in the skin in response to UVB damage, and that cutaneous HPV E6 proteins target and abrogate Bak function by promoting its proteolytic degradation both in vitro and in regenerated epithelium. Additionally, HPV positive skin cancers had undetectable levels of Bak in contrast to HPV negative cancers, which expressed Bak. This study supports a link between the virus and UVB in the induction of HPV-associated skin cancer and reveals a survival mechanism of virally infected cells.

The association of certain human papillomavirus (HPV) types with the majority of human cervical carcinomas suggests a role for the virus in the development of this type of cancer. In this paper, we have examined the transforming properties of several HPV types where the early region genes of the virus are under the control of a strong heterologous promoter and show that major differences exist between the HPV types in their ability to transform primary rat kidney epithelial cells in conjunction with an activated ras oncogene. Those HPV types most commonly found in carcinomas–types 16, 18, 31 and 33–are capable of co‐operating with ras to transform primary cells, but those types most commonly found in benign lesions–types 6 and 11–are not. We further demonstrate that the E7 gene of HPV16 by itself is sufficient to co‐operate with activated ras to produce transformed cells which are tumorigenic in immunocompetent animals.

Human papillomaviruses (HPVs) are DNA tumour viruses that induce hyperproliferative lesions in cutaneous and mucosal epithelia. The relationship between HPV and nonmelanoma skin cancer (NMSC) is important clinically since NMSC is the most common form of malignancy among fair-skinned populations. It is well established that solar ultraviolet (UV) irradiation is the major risk factor for developing NMSC, but a pathogenic role for HPV in the development of NMSC has also been proposed. Recent molecular studies reveal a likely role for HPV infection in skin carcinogenesis as a co-factor in association with UV. This review summarizes the literature describing these data, highlights some of the important findings derived from these studies, and speculates on future perspectives.

The major regulator of papillomavirus transcription is encoded by the viral E2 gene. The E2 gene has been well characterized in bovine papillomavirus (BPV) where it encodes at least three different polypeptides which differentially affect viral gene expression. In human papillomaviruses (HPVs) the E2 gene product is much less well characterized. In this study we have analysed the mechanism of action of the HPV‐16, HPV‐18 and BPV‐1 E2 proteins in cervical keratinocytes. We show that the full length HPV E2 protein acts as a potent transcriptional activator of viral gene expression in both normal and immortalized keratinocytes. In contrast, the BPV‐1 E2 protein produces transcriptional repression under identical conditions. A cDNA encoding the C‐terminal half of the HPV‐16 E2 protein in these assays weakly repressed viral gene expression. Further, co‐transfection of this cDNA with the full length clone progressively abolishes the activation in trans by the full length HPV E2 protein. Gel retardation assays have defined a number of protein complexes between the long and short forms of E2 but with no evidence for preferential DNA binding. These results define two distinct activities for the HPV‐16 E2 protein, indicate functional differences with the BPV E2 protein and suggest that splicing of the HPV E2 mRNA is a critical mechanism for controlling viral gene expression.

In addition to their role in anogenital cancer, human papillomaviruses (HPVs) are also involved in the development of a range of cutaneous lesions. HPV types 5 and 8 are associated with the development of skin cancers in individuals with Epidermodysplasia verruciformis (EV). A broad spectrum of HPV types are also commonly found in non-melanoma skin cancers in immunocompromised individuals, such as organ transplant recipients. The skin cancers in EV and immunocompromised patients occur predominantly at body sites exposed to ultra violet (UV) radiation, pointing to a key role for UV in their development. Here we show that the E6 protein from a range of cutaneous HPV types e ectively inhibits apoptosis in response to UV damage. This occurs in both p53 null and wild type cells and does not require p53 degradation. Oncogene (2000) 19, 592 ± 598.

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Context: Polycystic ovary syndrome (PCOS) represents the most common endocrine abnormality in women of reproductive age. The cause of PCOS remains largely unknown, but studies suggest an intrinsic ovarian abnormality.Objective: The objective of the study was to test our hypothesis that differences in granulosa cell proliferation and apoptosis may underlie abnormalities that affect follicular development.Design: Granulosa cells were prepared from follicular fluid aspirated from 4-to 8-mm follicles of unstimulated ovaries during routine laparoscopy or laparotomy from women with anovulatory PCOS and those with regular ovulatory cycles. Setting:The study was conducted at a university hospital.Patients: Fourteen women with anovulatory PCOS and nine women with regular ovulatory cycles participated in the study. Main Outcome Measures:Immunocytochemistry on granulosa cells to investigate apoptotic and proliferation rates, together with real-time RT-PCR to analyze gene expression profiles of apoptotic regulators, was measured.Results: Significantly lower apoptotic rates were found in granulosa cells from patients with PCOS, compared with women with regular ovulatory cycles (P ϭ 0.004). Lower apoptotic rates were associated with decreased levels of the apoptotic effector caspase-3 (P ϭ 0.001) and increased levels of the anti-apoptotic survival factor cellular inhibitor of apoptosis proteins-2 in the PCOS group that were coupled to higher proliferation rates (P ϭ 0.032). Gene expression profiling confirmed the immunocytochemical findings. Conclusions:Our findings indicate that there are significant differences in the rate of cell death and proliferation in granulosa cell populations in PCOS patients. These are associated with decreased expression of apoptotic effectors and increased expression of a cell survival factor. These results provide new insights that may be useful in developing specific therapeutic intervention strategies in PCOS. (J Clin Endocrinol Metab 93: 881-887, 2008) P olycystic ovary syndrome (PCOS) is a common endocrine abnormality in women of reproductive age, affecting 6.6 -8% of women in this age group (1). It is the main cause of anovulatory infertility and is characterized by chronic anovulation, hyperandrogenemia, and polycystic ovaries on ultrasound scan (2). Abbreviations: Bcl, B-cell lymphoma; BMI, body mass index; cIAP, cellular IAP; DHEAS, dehydroepiandrosterone sulfate; IAP, inhibitor of apoptosis proteins; Mcl, myeloid leukemia cell differentiation protein; PCOS, polycystic ovary syndrome; TUNEL, terminal deoxynucleotidyl transferase biotin-deoxyuridine 5-triphosphate nick end labeling; XIAP, X-linked inhibitor of apoptosis protein.