Pawel G. Fuchs

Expression of p16 protein identifies a distinct entity of tonsillar carcinomas associated with human papillomavirus.

Recent analyses of head and neck squamous cell carcinomas revealed frequent infections by oncogenic human papillomavirus (HPV) type 16 in tonsillar carcinomas. Concerning involvement of risk factors, clinical course of the disease, and prognosis there are strong indications arguing that the HPV-positive tonsillar carcinomas may represent a separate tumor entity. Looking for a surrogate marker, which in further epidemiological studies could replace the laborious and expensive HPV detection and typing we analyzed p16 protein expression in 34 tonsillar carcinoma for correlation to HPV status and load of viral DNA. p16 has been shown to be of diagnostic value for clinical evaluation of cervical dysplasia. We found 53% of the tested tonsillar carcinomas to be HPV-positive. Fifty-six percent of all tumors tested were immunohistochemically positive for the p16 protein. In 16 of 18 of the HPV-positive carcinomas diffuse p16 expression was observed. In contrast, only one of the HPV-negative carcinomas showed focal p16 staining (P < 0.001). As determined by laser-assisted microdissection and quantitative real-time polymerase chain reaction, p16 expression correlated with the presence of HPV-DNA in the individual tumor specimens. Clinical outcome analysis revealed significant correlation of p16 expression with increased disease-free survival (P = 0.02). These data indicate that p16 is a technically simple immunohistological marker, applicable for routine pathological histology, and its prognostic value for survival is fully equivalent to HPV-DNA detection.

High prevalence of epidermodysplasia verruciformis-associated human papillomavirus DNA in actinic keratoses of the immunocompetent population

Skin cancers in both immunosuppressed and immunocompetent populations are associated with epidermodysplasia verruciformis human papillomavirus (EV-HPV) DNA. However, little is known about the prevalence of EV-HPVs in actinic keratoses in immunocompetent individuals. Actinic keratoses from 114 patients were classified as low-grade (n=76) or high-grade (n=38) according to the extent of histological atypia. HPV DNA was amplified from 54 frozen and 60 paraffin-embedded biopsy specimens by nested polymerase chain reaction (PCR) with several consensus and type-specific primers. PCR products were sequenced for typing. These results were compared with HPV detection in skin cancers (n=20) and Bowen’s disease (n=18). A broad spectrum of EV-HPV types including oncogenic HPV5 and HPV8 and partially characterized sequences were detected in actinic keratoses and cutaneous cancers. In actinic keratoses a higher prevalence of EV-HPV DNA was found in frozen tissues than in formalin-fixed tissues (85% vs 67%). There was no difference between the low- and high-grade actinic keratoses either in terms of EV-HPV DNA prevalence or the results of serological study using HPV8 virus-like particles. The detection rate of EV-HPVs was lower in skin cancers and Bowen’s disease. This would suggest involvement of EV-HPVs in the early stages of cutaneous oncogenesis.

Human papillomavirus-positive tonsillar carcinomas: a different tumor entity?

Abstract. Human papillomavirus (HPV) infections are thought to be one of the causal factors in the development of head and neck squamous cell carcinomas (HNSCC), particularly in tumors arising from the Waldeyers tonsillar ring. We screened 98 carefully stratified HNSCC and different control tissues for the presence of HPV DNA by nested polymerase chain reaction (PCR) specific for genital- and Epidermodysplasia verruciformis (EV)-associated HPVs and by HPV16-specific single step PCR. Typing was performed by direct sequencing and/or sequencing of cloned amplimers. On average HNSCC showed rather low HPV DNA prevalences; 18% of the oral cavity cancers, 8% of nasopharyngeal cancers, 25% of hypopharyngeal cancers and 7% of laryngeal cancers were HPV DNA positive. In contrast, HPV sequences could be detected in 45% of the oropharyngeal cancers, particularly tonsillar carcinomas (58%). Tonsillar carcinomas were significantly more likely to be HPV positive than tumors from any other site (P<0.001). All tonsillar cancers contained oncogenic HPV types, predominantly HPV16 (13 of 14; 93%). Unaffected tonsils were available from two of these patients, but both tested negative for HPV DNA. Furthermore, no HPV DNA could be found in tonsillar biopsy specimens from control groups. Localization and load of HPV DNA was determined in HPV16-positive tonsillar carcinomas, their metastases and in unaffected mucosa using laser-assisted microdissection and subsequent real time fluorescence PCR. We demonstrated that the HPV genome is located in the cancer cells, whereas the infection of normal mucosa is a rare event. Quantification of HPV16 DNA in samples of seven patients yielded viral loads from 6 to 153 HPV DNA copies per β-globin gene copy and the load values in both locations were roughly comparable. These loads are comparable with data shown for other HPV-associated lesions. Statistical evaluation of data related to clinicopathological parameters showed a significant correlation of the HPV positivity of tonsillar carcinomas with tumor grading (P=0.008) and alcohol consumption (P=0.029). Taken together our findings show a preferential association of HPV DNA with tonsillar carcinomas. Furthermore our results argue for HPV-positive tonsillar carcinomas representing a separate tumor entity, which is less dependent on conventional HNSCC risk factors.

The E7 Protein of Cutaneous Human Papillomavirus Type 8 Causes Invasion of Human Keratinocytes into the Dermis in Organotypic Cultures of Skin

Human papillomaviruses (HPV) have been implicated in the development of nonmelanoma skin cancer (NMSC). The molecular mechanisms by which these viruses contribute towards NMSC are poorly understood. We have used an in vitro skin-equivalent model generated by transducing primary adult human epidermal keratinocytes with retroviruses expressing HPV genes to investigate the mechanisms of viral transformation. In this model, keratinocytes expressing HPV genes are seeded onto a mesenchyme composed of deepidermalized human dermis that had been repopulated with primary dermal fibroblasts. Expression of the HPV8 E7 gene caused both an enhancement of terminal differentiation and hyperproliferation, but most strikingly, the acquisition of the ability to migrate and invade through the underlying dermis. The basement membrane integrity was disrupted in a time-dependent manner in areas of invading keratinocytes, as evidenced by immunostaining of its protein components collagen types VII, IV, and laminin 5. This was accompanied by the overexpression of extracellular matrix metalloproteinases MMP-1, MMP-8, and MT-1-MMP. These results suggest that the cutaneous HPV type 8 that is frequently found in NMSC of epidermodysplasia verruciformis patients may actively promote an invasive keratinocyte phenotype. These findings also highlight the importance of epithelial-extracellular matrix-mesenchymal interactions that are required to support cell invasion.

The presence of antibodies against virus‐like particles of epidermodysplasia verruciformis‐associated humanpapillomavirus type 8 in patients with actinic keratoses

Epidermodysplasia verruciformis‐associated human papillomaviruses (EV‐HPVs) are possibly involved in the development of actinic keratoses and may play a part in the pathogenesis of squamous cell carcinoma (SCC) of the skin, as the DNA of these viruses is frequently detected in biopsies of such lesions. Properly designed epidemiological studies, using serological tests to investigate the role of infection with EV‐HPVs in cutaneous oncogenesis, are still rare. An IgG‐specific enzyme‐linked immunosorbent assay using virus‐like particles composed of the major capsid protein L1 of the EV‐specific HPV 8 (HPV 8 VLPs) was developed and used to test the seroprevalence of HPV 8 in 114 inhabitants of a tropical island, of whom 13 had developed SCC, and 19 had developed basal cell carcinoma. Gender, age, eye and hair colour, sun exposure and number of actinic keratoses were recorded for all individuals. The presence of antibodies against HPV 8 VLPs was associated with the development of large numbers of actinic keratoses. After adjusting for gender, age, eye and hair colour, and sun exposure, the odds ratio to develop 37 (the median in this dataset) or more actinic keratoses in the presence of antibodies against HPV 8 VLPs was 2·3 (95% confidence interval: 1·0; 5·3). Similarly, after adjustment for the same factors, the presence of these antibodies was associated with SCC with an odds ratio of 3·1 (0·74; 13·3), but the small number of individuals with SCC does not permit any definite conclusions. The presence of these antibodies did not appear to be associated with basal cell carcinoma as, after adjustment for the same factors, the odds ratio was 0·73 (0·23; 2·4). This study provides serological evidence that infection with EV‐HPVs may play a part in the pathogenesis of actinic keratoses. The role of EV‐HPVs in the development of SCC, however, remains to be elucidated.

Nine‐year follow‐up of a case of Grzybowski type multiple keratoacanthomas and failure to demonstrate human papillomavirus

Summary We describe a patient with a 9‐year history of generalized eruptive keratoacanthoma (KA) of the Grzybowski type whose multiple skin lesions showed steady progression, resulting in a sclerotic, mask‐like facial expression and ectropion. Eleven tumour biopsies representing lesions of different stages and localizations (erupting and regressing KAs, biopsies from non‐involved light‐protected and light‐exposed skin, dermatosclerosis and squamous cell carcinomas) were analysed for human papillomavirus (HPV) sequences using a polymerase chain reaction approach capable of detecting the majority of all presently known HPV genotypes. None of the biopsy specimens proved to be HPV‐positive, although HPV was detected in weakly and heavily affected control specimens by the method applied. These findings suggest an HPV‐independent aetiology of this rare type of multiple KA.

Cloning and Characterization of Papillomavirus Type 2c DNA

Human papillomavirus (HPV) DNA was isolated from a clinically diagnosed flat wart and proved to be related to HPV2. The isolate showed 55% cross-hybridization with HPV2a. A physical map of restriction enzyme cleavage sites differed completely from those of HPV2a and HPV2b. The new HPV2 subtype, which will be classified as HPV2c, was found to be very prevalent in common warts.

Unique topography of DNA-protein interactions in the non-coding region of epidermodysplasia verruciformis-associated human papillomaviruses

The non-coding region (NCR) of the epidermodysplasia verruciformis (EV)-associated human papillomavirus 8 (HPV-8) has been investigated for sequence-specific DNA-protein interactions with nuclear proteins from epithelial HeLa cells. Using DNase I protection analysis 18 footprints could be found within the HPV-8 NCR, covering altogether over 60% of both DNA strands. Several footprints coincided with the known binding sites of transcription factors (NF1, AP1, octamer and PEA3 consensus sequences); the other displayed no obvious similarities in this regard. The overall distribution of sequences involved in DNA-protein interactions differed clearly from the binding patterns reported for other HPVs. Parts of the two binding sites for the viral trans-activator protein E2 were shown to interact with non-E2 factors. The EV-specific NCR motifs M33, M29 and A/T box were all involved in protein binding. By comparing the footprints within the respective motifs of the closely related types HPV-8 and -19, quantitative and qualitative differences were detected for M33 and the A/T box.