The causal role of human papillomavirus infections in cervical cancer has been documented beyond reasonable doubt. The association is present in virtually all cervical cancer cases worldwide. It is the right time for medical societies and public health regulators to consider this evidence and to define its preventive and clinical implications. A comprehensive review of key studies and results is presented.

https://jcp.bmj.com/content/jclinpath/55/4/244.full.pdf

The causal relation between human papillomavirus and cervical cancer

Somatic mutations in the TP53 gene are one of the most frequent alterations in human cancers, and germline mutations are the underlying cause of Li-Fraumeni syndrome, which predisposes to a wide spectrum of early-onset cancers. Most mutations are single-base substitutions distributed throughout the coding sequence. Their diverse types and positions may inform on the nature of mutagenic mechanisms involved in cancer etiology. TP53 mutations are also potential prognostic and predictive markers, as well as targets for pharmacological intervention. All mutations found in human cancers are compiled in the IARC TP53 Database (http://www-p53.iarc.fr/). A human TP53 knockin mouse model (Hupki mouse) provides an experimental model to study mutagenesis in the context of a human TP53 sequence. Here, we summarize current knowledge on TP53 gene variations observed in human cancers and populations, and current clinical applications derived from this knowledge.

/pdf/tp53-mutations-in-human-cancers-origins-consequences-and-3yze3radrd.pdf

TP53 Mutations in Human Cancers: Origins, Consequences, and Clinical Use

Skin cancers are the most common tumors in patients who have received organ transplants. This review discusses the epidemiology, pathogenesis, and management of squamous-cell and basal-cell carcinomas, cancers of the anogenital region, Kaposi's sarcoma, melanoma, neuroendocrine skin carcinoma, and cutaneous manifestations of lymphoma in transplant recipients.

Skin cancers after organ transplantation.

Abnormalities of the p53 tumour suppressor gene are among the most frequent molecular events in human and animal neoplasia. Moreover, p53 is one of the most studied proteins in the whole of contemporary biology, with more than 12,500 papers so far written! In this review the choice has been deliberately made not to be fully comprehensive in the coverage of the huge p53 literature. Rather attention is focused on a small number of recent developments which are reviewed in the context of modern models of p53 function. Progress in the analysis of signalling to p53 including phosphorylation cascades, and interactions with proteins such as mdm2 and ARF are highlighted. The plethora of protein-protein interactions is discussed, as are the strategies for defining downstream targets of p53. Finally, the emerging biology of p53 homologues is considered. The need for bridging the gap between reductionist, biochemical and biophysical studies and biological and genetic analysis is emphasized. Only this will provide the needed framework for utilizing the information in clinical care.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/%28SICI%291096-9896%28199901%29187%3A1%3C112%3A%3AAID-PATH250%3E3.0.CO%3B2-3

The p53 pathway

During the past 20 years, several types of human papillomaviruses (HPVs) have been identified that cause specific types of cancers. The etiology of cancer of the cervix has been linked to several types of HPV, with a high preponderance of HPV16. The role of these virus infections has been established 1) by the regular presence of HPV DNA in the respective tumor biopsy specimens, 2) by the demonstration of viral oncogene expression (E6 and E7) in tumor material, 3) by the identification of transforming properties of these genes, 4) by the requirement for E6 and E7 expression for maintaining the malignant phenotype of cervical carcinoma cell lines, 5) by the interaction of viral oncoproteins with growth-regulating host-cell proteins, and 6) by epidemiologic studies pointing to these HPV infections as the major risk factor for cervical cancer development. In addition to cancer of the cervix, a major proportion of anal, perianal, vulvar, and penile cancers appears to be linked to the same HPV infections. In addition, close to 20% of oropharyngeal cancers contain DNA from the same types of HPV. Recent evidence also points to a possible role of other HPV infections in squamous cell carcinomas of the skin. This review covers recent developments in understanding molecular mechanisms of HPV carcinogenesis, mainly discussing functions of viral oncoproteins and the regulation of viral oncogenes by host-cell factors. Modifications in host-cell genes, most likely engaged in the control of HPV gene expression in proliferating cells, emerge as important events in HPV-mediated carcinogenesis.

/pdf/papillomaviruses-causing-cancer-evasion-from-host-cell-1o32pgq6iv.pdf

Papillomaviruses Causing Cancer: Evasion From Host-Cell Control in Early Events in Carcinogenesis

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

Role of a p53 polymorphism in the development of human papillomavirus-associated cancer.

The wild-type p53 protein exhibits a common polymorphism at amino acid 72, resulting in either a proline residue (p53Pro) or an arginine residue (p53Arg) at this position. Despite the difference that this change makes in the primary structure of the protein resulting in a difference in migration during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, no differences in the biochemical or biological characteristics of these wild-type p53 variants have been reported. We have recently shown that p53Arg is significantly more susceptible than p53Pro to the degradation induced by human papillomavirus (HPV) E6 protein. Moreover, this may result in an increased susceptibility to HPV-induced tumors in homozygous p53Arg individuals. In further investigating the characteristics of these p53 variants, we now show that both forms are morphologically wild type and do not differ in their ability to bind to DNA in a sequence-specific manner. However, there are a number of differences between the p53 variants in their abilities to bind components of the transcriptional machinery, to activate transcription, to induce apoptosis, and to repress the transformation of primary cells. These observations may have implications for the development of cancers which harbor wild-type p53 sequences and possibly for the ability of such tumors to respond to therapy, depending on their p53 genotype.

Two Polymorphic Variants of Wild-Type p53 Differ Biochemically and Biologically

Storey et al. reply — These reports assess the frequency of the p53Arg allele in different populations and conclude that homozygous p53Arg is not a risk factor for cancer associated with human papilloma virus (HPV). The functional differences between the p53 isoforms that we have described1,2 provoked our initial epidemiological study. As we concluded then, it is crucial that investigations should be extended to different populations, and we are encouraged that such studies are underway.

Ann Kalita

Papers

Role of a p53 polymorphism in the development of human papillomavirus-associated cancer.

Two Polymorphic Variants of Wild-Type p53 Differ Biochemically and Biologically

p53 polymorphism and risk of cervical cancer

A genetic polymorphism determines susceptibility to human papillomavirus associated cancers