RESUMO
El objetivo de este estudio fue evaluar el efecto de la radiación ultravioleta (UV) B sobre la expresión del factor de crecimiento transformante (TGF) ß1 por fibroblastos de mucosa oral, con el objetivo de dilucidar si este tipo celular puede contribuir a la expresión de TGFß1 en bermellón labial sobreexpuesto a la radiación UV. Se obtuvieron cultivos primarios de fibroblastos desde explantes de mucosa bucal, los que fueron irradiados con una dosis única de luz UVB (60 mJ/cm2). Se midió proliferación celular con el método MTT, y la expresión de TGFß1, a nivel de ARN mensajero (normalizado a GAPDH) por RT-PCR y a nivel de proteína mediante inmunofluorescencia. Se observó una disminución de la proliferación celular de los fibroblastos de mucosa oral a las 24 hrs post-irradiación en relación a los fibroblastos no irradiados (P<0,05, Mann Whitney). No se encontraron diferencias entre los fibroblastos control y los irradiados en la expresión de TGFß-1 ni a nivel de mensajero (0,5 y 6 h post-irradiación), ni de proteína (24 h post-irradiación). Los resultados sugieren que los fibroblastos de mucosa oral presentan una disminución de su proliferación en respuesta a una dosis única de radiación UVB, sin que se afecte la expresión de TGFß-1, la que fue similar a los fibroblastos no irradiados. Esto sugiere que los fibroblastos contribuirían a la producción de TGFß-1 en respuesta a la exposición crónica a UVB del bermellón labial.
The objective of this study was to characterize the effect of Ultraviolet (UV) B irradiation on the expression of transforming growth factor (TGF) ß1 by oral mucosa fibroblasts, in order to assess if these cells contribute to the production of TGFß-1 in UV-irradiated lip vermillion. Primary cultures of fibroblasts were obtained from oral mucosa explants, and were irradiated with a single dose of UVB light (60 mJ/cm2). The effects of UVB radiation on cell proliferation was evaluated by the MTT method. The effects of UVB on the expression of TGF-ß1 was analyzed by RT-PCR (normalized to GAPDH) and by immunofluorescence. The results showed a decrease in the proliferation of UVB-irradiated fibroblasts as compared to controls at 24h post-irradiation (p<0.05). No variations in the expression of TGFß1, both at the mRNA and protein level, were observed between control and UVB-irradiated fibroblasts during the first 24 h after irradiation. Oral mucosa fibroblasts have reduced proliferation in response to a single dose of UVB, but their expression of TGFß1 was not affected. This suggests that oral mucosa fibroblasts may contribute to the production of TGFß1 in the lip vermillion independent of UVB exposure.
Assuntos
Humanos , Mucosa Bucal/metabolismo , Mucosa Bucal/efeitos da radiação , Fator de Crescimento Transformador beta/efeitos da radiação , Raios Ultravioleta , Proliferação de Células , Fibroblastos/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
High-risk human papillomaviruses (HR-HPVs) are the causative agents of cervical cancer, and they are also associated with a subset of head and neck squamous cell carcinomas. In addition, HPVs have also been postulated in the development of non-melanoma skin cancers (NMSC). In these cancers, the oncogene E6 is best known for its ability to inactivate the tumor suppressor p53 protein. Interestingly, in transgenic mice for HPV16 E6 (K14E6), it was reported that E6 alone induced epithelial hyperplasia and delay in differentiation in skin epidermis independently of p53 inactivation. Transforming growth factor ß (TGFß) is an important regulator of cell growth/differentiation and apoptosis, and this pathway is often lost during tumorigenesis. Ultraviolet radiation B (UVB) exposure activates diverse cellular responses, including DNA damage and apoptosis. In this study, we investigated whether the E6 oncogene alone or in combination with UVB dysregulate some components of the TGFß pathway in the epidermis of K14E6 mice. We used 8-day-old K14E6 and non-transgenic mice irradiated and unirradiated with a single dose of UVB. We found that the E6 oncogene and UVB irradiation impair the TGFß pathway in epidermis of K14E6 mice by downregulation of the TGFß type II receptor (TßRII). This loss of TßRII prevents downstream activation of Smad2 and target genes as p15, an important regulator of cell cycle progression. In summary, the TGFß signalling in cells of the epidermis is downregulated in our mouse model by both the E6 oncoprotein and the UVB irradiation.
Assuntos
Epiderme/efeitos da radiação , Proteínas Oncogênicas Virais/genética , Proteínas Repressoras/genética , Transdução de Sinais/genética , Transdução de Sinais/efeitos da radiação , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/efeitos da radiação , Raios Ultravioleta , Animais , Apoptose/efeitos da radiação , Dano ao DNA/efeitos da radiação , Modelos Animais de Doenças , Relação Dose-Resposta à Radiação , Regulação para Baixo/genética , Regulação para Baixo/efeitos da radiação , Epiderme/metabolismo , Epiderme/patologia , Camundongos , Camundongos Transgênicos , Proteínas Oncogênicas Virais/metabolismo , Fosforilação , Proteínas Repressoras/metabolismo , Proteína Smad2 , Fator de Crescimento Transformador beta/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/efeitos da radiaçãoRESUMO
OBJECTIVE: The present study histologically and radiologically evaluates the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2) in a natural inorganic bone mineral scaffold from a bull calf femur and irradiation with low-power light laser. MATERIALS AND METHODS: The right and left hind limbs of 16 rats were shaved and an incision was made in the muscle on the face corresponding to the median portion of the tibia, into which rhBMP-2 in a scaffold of inorganic bone was implanted. Two groups of limbs were formed: control (G1) and laser irradiation (G2). G2 received diode laser light applied in the direction of the implant, at a dose of 8 J/cm2 for three minutes. On the 7th, 21st, 40th and 112th days after implantation, hind limbs of 4 animals were radiographed and their implants removed together with the surrounding tissue for study under the microscope. The histological results were graded as 0=absence, 1=slight presence, 2=representative and 3=very representative, with regard to the following events: formation of osteoid structure, acute inflammation, chronic inflammation, fibrin deposition, neovascularization, foreign-body granuloma and fibrosis. RESULTS: There were no statistically significant differences in these events at each evaluation times, between the two groups (P > 0.05; Mann-Whitney test). Nevertheless, it could be concluded that the natural inorganic bone matrix with rhBMP-2, from the femur of a bull calf, is a biocompatible combination. CONCLUSIONS: Under these conditions, the inductive capacity of rhBMP-2 for cell differentiation was inhibited. There was a slight acceleration in tissue healing in the group that received irradiation with low-power laser light.