E6 and E7 proteins from different beta-papillomaviruses types do not interfere in UVB-induced apoptosis of HaCaT keratinocytes

Beta-papillomaviruses (beta-HPV) have been linked to the development of skin cancer in humans. Because both E6 and E7 proteins from beta-HPV have been involved in the potential carcinogenicity of these viruses, we investigated their role on UVB-induced apoptosis in HaCaT cell line. HaCaT cells have been transduced with both E6/E7 using a retroviral system and treated with PRIMA-1. Apoptosis was assessed by flow cytometry to measure mitochondrial membrane potential and DNA fragmentation. HaCat keratinocytes transduced with both E6 and E7 genes of seven beta-HPV types (HPV5, HPV8, HPV14, HPV24, HPV36, HPV38 and HPV49) did not demonstrate any inhibition of UVB-induced apoptosis, even after p53 reactivation through PRIMA-1. Our data suggest that the expression of E6 and E7 exert different modulatory effects on UVB-induced apoptosis according to beta-HPV types and to the cellular genetic context.

[Intraepithelial lesions and neoplasia associated with human papillomavirus infection]

Anogenital lesions induced by human papillomaviruses (HPV) are due to both high-risk HPV types involved in carcinogenesis of the cervix (and also, to a lesser extent, of the vulva, anus and vagina) and to low-risk HPV types that cause external genital warts in the perianal region, perineum, vulva and vagina (less often the cervix). Cervical cancer is thus virus-induced, and there is a continuum from intraepithelial lesions to invasive cancer. This offers the opportunity to screen cervical smears for cytological abnormalities or to detect high-risk HPV infection by molecular methods. Although the causal link between human genital papillomavirus infection and cervical neoplasia is well established, the role of beta-HPV in non melanoma skin cancers is unclear.

[Clinical and benign aspects of human papillomavirus-associated lesions]

Human papillomaviruses (HPV) are found in most human epithelia and some tumors. Most HPV strains associated with cutaneous lesions belong to three types, named alpha, beta and gamma. Although the causal link between genital human papillomavirus infection and cervical neoplasia is well established, the role of beta-HPV in non melanoma skin cancers is unclear. HPV mainly causes benign cutaneous lesions on the hands and soles. Genital HPV infection is the most common sexually transmitted infection. It is generally asymptomatic. The genitals can be infected by two low-risk HPV types (6 and 11), which are responsible for benign anogenital warts (condylomata acuminata). The implications of anogenital warts in children are highly controversial as regards sexual abuse. Treatments (chemical, physical or immunological) are lengthy, expensive, inconvenient and often painful. Recurrence is frequent because of HPV persistence in perilesional skin.

Immunohistochemical analysis of CD4+ and CD8+ T-cell subsets in high risk human papillomavirus-associated pre-malignant and malignant lesions of the uterine cervix

OBJECTIVES

Humoral and cellular immune responses are likely to play a key role for the clearance or persistence and progression of high risk (HR) HPV-associated cervical lesions. Although there are many studies describing the systemic T-cell responses to HPV16 and 18 proteins, few data are available regarding the cellular mucosal immune responses. We used immunohistochemistry to characterize populations of T-immune cells (CD4+, CD8+, CD45RO+) in HR-HPV-infected precancerous and cancerous lesions of the uterine cervix.

METHODS

Four biopsies from normal cervix, 9 CIN1 which have regressed (rCIN), 5 CIN1 which have progressed (pCIN) to high grade lesions, 13 CIN3 and 11 invasive carcinomas were included. All dysplasias and carcinomas were HR-HPV-positive and low-risk-HPV-negative. They were stained with monoclonal antibodies specific for CD4, CD8 and CD45RO and examined by microscopy.

STATISTICAL ANALYSIS

The Kruskal-Wallis test and the Siegel's and Castelan's method were used. RESULTS.: CD4+ cells predominated in regressing CIN1 both within the stroma and the epithelium with the highest CD4+/CD8+ ratio compared with pCIN1, CIN3 and invasive carcinoma. At the exception of CD45RO+ cells, T cells were detected with similar frequencies in both pCIN1 and CIN3. However, in 7 out of 10 CIN3, CD4+ and CD8+ cells were visible as organized lymphoid follicle structure. The CD8+ and CD45RO+ cells far exceeded the CD4+ cells in invasive cancers.

CONCLUSIONS

Density and distribution of immune T cells depend on the malignant potential of HR-HPV lesions. These results suggest that the studied lymphocyte subsets have an important role to fulfil during the natural history of HR-HPV-associated lesions.