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

Abstract

: 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.

An Ethanol Extract Derived from Bonnemaisonia hamifera Scavenges Ultraviolet B (UVB) Radiation-Induced Reactive Oxygen Species and Attenuates UVB-Induced Cell Damage in Human Keratinocytes

“…A number of recent studies show that UVB light induces apoptosis in keratinocytes [24,25,26]. In keeping with this observation, intact nuclei were observed in control, and cells treated only with BHE, whereas significant nuclear fragmentation (characteristic of apoptotic body formation) was observed in UVB-irradiated cells (apoptotic index, 19.3).…”

Mapping of Betapapillomavirus Human Papillomavirus 5 Transcription and Characterization of Viral-Genome Replication Function

“…However, E6 gene expression from several cutaneous HPV types protects keratinocytes from UV-B-induced apoptosis (50,51) by mediating the degradation or reduction of the levels of the proapoptotic Bak protein, thereby preventing the release of proapoptotic factors from the mitochondria (52,53). However, this finding was not confirmed when E6/E7 was expressed in HaCat keratinocytes (54). It has been demonstrated that wt p53 induces the downregulation of E6 from HPV5, HPV20, and HPV38 (55), supporting the notion of a role for E6 in oncogenesis.…”

E6 and E7 of human papillomavirus type 18 and UVB irradiation corporately regulate interleukin‐6 and interleukin‐8 expressions in basal cell carcinoma

“…HaCat keratinocytes transduced with both E6 and E7 genes of beta-HPV types do not demonstrate any inhibition of UVB-induced apoptosis (26). In our study, repression of E6/E7 expression concomitantly reduced the IL-6 and IL-8 expressions and cell proliferation.…”