Human papillomavirus gene expression in cutaneous squamous cell carcinomas from immunosuppressed and immunocompetent individuals

Abstract

Epidermodysplasia verruciformis (EV)-type human papillomavirus (HPV) DNA have been detected by PCR in squamous cell carcinomas (SCC) from both organ transplant recipients (OTR) and immunocompetent individuals. Their role in skin cancer remains unclear, and previous studies have not addressed whether the viruses are transcriptionally active. We have used in situ hybridization to investigate the transcriptional activity and DNA localization of HPV. EV-HPV gene transcripts were demonstrated in four of 11 (36%) OTR SCC, one of two (50%) IC SCC, and one of five (20%) OTR warts positive by PCR. Viral DNA co-localized with E2/E4 early region gene transcripts in the middle or upper epidermal layers. Non-EV cutaneous HPV gene transcripts were demonstrated in one of five (20%) OTR SCC and four of 10 (40%) OTR warts. In mixed infections transcripts for both types were detected in two of six (33%) cases. Our results provide evidence of EV-HPV gene expression in SCC; although only a proportion of tumors were positive, the similarly low transcriptional activity in warts suggests this is an underestimate. These observations, together with emerging epidemiological and functional data, provide further reason to focus on the contribution of EV-HPV types to the pathogenesis of cutaneous SCC.

Figure 1

In situ hybridisation of viral wart 5. a, DNA probe for HPV2; antisense riboprobes for: b, keratin 10; c, HPV2 L1; d, HPV2 E4; e, HPV2 L2; f, HPV2 E7.

Figure 2

In situ hybridisation of viral wart 8. DNA probes for: a, HPV2; b, HPV3; c, antisense riboprobe for HPV2 E4.

Figure 3

In situ hybridisation of SCC4. H&E staining of sections: a, at low magnification showing carcinoma in situ and invasive tumour; b, at high magnification showing an in situ portion of this SCC which was contiguous with the invasive component shown in (a). Some of the cells have enlarged and pale-staining cytoplasm which might be keeping with a viral cytopathic effect; ISH shows the carcinoma in situ component using: c, DNA probe for HPV20; antisense (d) and sense (e) riboprobes for HPV20 E4; antisense riboprobes for f, HPV20 E7; g, HPV20 E6.

Figure 4

In situ hybridisation of SCC18. a, H&E staining of section; antisense riboprobes for b, HPV3 E4; c, HPV15 E4.

Figure 5

In situ hybridisation of SCC2. a, H&E staining of section; b, antisense riboprobe for HPV20 E4; antisense (c) and sense (d) riboprobes for HPV5 E4

Figure 6

In situ hybridisation of SCC15. a, H&E staining of section; DNA probes for: b, HPV5, c, negative control; antisense (d) and sense (e) riboprobes for HPV5 E4.

Figure 7

Schematic representation of the location of subgenomic HPV riboprobes in the HPV genome. The start and end nucleotide positions are shown for the various HPV types.