RESUMEN
OBJECTIVES: This study aimed to determine the importance of the shear-stress-sensitive calcium channels Trpc1, Trpm7, Trpp2, Trpv2 (transient receptor potential cation channel, subfamily V, member 2) and Trpv4 for cerebral arteriogenesis. The expression profiles were analysed, comparing the stimulation of collateral growth by target-specific drugs to that achieved by maximum increased fluid shear stress (FSS). DESIGN: A prospective, controlled study wherein rats were subjected to bilateral carotid artery ligature (BCL), or BCL + arteriovenous fistula, or BCL + drug application. METHODS: Messenger RNA (mRNA) abundance and protein expression were determined in FSS-stimulated cerebral collaterals by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry. Drugs were applied via osmotic mini pumps and arteriogenesis was evaluated by post-mortem angiograms and Ki67 immunostaining. RESULTS: Trpv4 was the only mechanosensitive Trp channel showing significantly increased mRNA abundance and protein expression after FSS stimulation. Activation of Trpv4 by 4α-phorbol-12,13-didecanoate caused significantly enhanced collateral growth (length: 4.43 ± 0.20 mm and diameter: 282.6 ± 8.1 µm) compared with control (length: 3.80 ± 0.06 mm and diameter: 237.3 ± 5.3 µm). Drug application stimulated arteriogenesis to almost the same extent as did maximum FSS stimulation (length: 4.61 ± 0.07 mm and diameter: 327.4 ± 12.6 µm). CONCLUSIONS: Trpv4 showed significantly increased expression in FSS-stimulated cerebral collaterals. Pharmacological Trpv4 activation enhanced cerebral arteriogenesis, pinpointing Trpv4 as a possible candidate for the development of new therapeutic concepts.
Asunto(s)
Circulación Cerebrovascular/fisiología , Circulación Colateral/fisiología , Regulación de la Expresión Génica , Arteriosclerosis Intracraneal/etiología , Forboles/efectos adversos , ARN Mensajero/genética , Canales Catiónicos TRPV/genética , Animales , Circulación Cerebrovascular/efectos de los fármacos , Circulación Colateral/efectos de los fármacos , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Inmunohistoquímica , Arteriosclerosis Intracraneal/genética , Arteriosclerosis Intracraneal/metabolismo , Masculino , Neovascularización Patológica/inducido químicamente , Neovascularización Patológica/metabolismo , Presión Osmótica , Reacción en Cadena de la Polimerasa , Estudios Prospectivos , Ratas , Ratas Sprague-Dawley , Canales Catiónicos TRPV/biosíntesis , Canales Catiónicos TRPV/efectos de los fármacosRESUMEN
By means of a two-stage promotion protocol in mouse epidermis with 12-O-tetradecanoylphorbol-13-acetate as first-stage promoter and 12-O-retinoylphorbol-13-acetate as second-stage promoter, the effects of the former that are critical and obligatory for tumor promotion were shown to be irreversible in nature for at least 8 weeks. The reversibility of tumor promotion was related to the second stage of promotion, reflecting the reversibility of epidermal hyperplasia induced by 12-O-tetradecanoylphorbol-13-acetate.
Asunto(s)
Carcinógenos/farmacología , Ésteres del Forbol/efectos adversos , Forboles/efectos adversos , Neoplasias Cutáneas/inducido químicamente , Acetato de Tetradecanoilforbol/efectos adversos , Animales , Línea Celular , Epidermis/efectos de los fármacos , Femenino , Hiperplasia/inducido químicamente , Ratones , Ratones Endogámicos , Neoplasias Experimentales/inducido químicamente , Lesiones Precancerosas/inducido químicamente , Factores de TiempoAsunto(s)
Queratinas/análisis , Ésteres del Forbol/efectos adversos , Forboles/efectos adversos , Piel/patología , Animales , Dorso , Oído , Hiperplasia , Queratinas/metabolismo , Ratones , Neoplasias Experimentales/inducido químicamente , Piel/análisis , Piel/efectos de los fármacos , Neoplasias Cutáneas/inducido químicamente , Cola (estructura animal)Asunto(s)
Cocarcinogénesis , Metotrexato/uso terapéutico , Neoplasias/patología , Forboles/efectos adversos , Acetato de Tetradecanoilforbol/efectos adversos , Animales , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Resistencia a Medicamentos , Genes , Humanos , Ratones , Mutación , Neoplasias/tratamiento farmacológico , Tetrahidrofolato Deshidrogenasa/genéticaRESUMEN
The effect of the tumor promoter TPA and its inactive structural analogue 4-O-methyl-TPA on the induction of dorsal skin melanosis in the normal Syrian golden hamster and on the promotion of melanomas in DMBA-initiated animals was investigated. Both phenomena were observed in TPA-treated hamsters but could not be detected after exposure of animals to 4-O-methyl-TPA. In contrast to results obtained with a variety of other laboratory animals, neither TPA nor 4-O-methyl-TPA were able to induce epidermal hyperplasia of hamster dorsal skin.
Asunto(s)
Melanocitos/efectos de los fármacos , Melanoma/inducido químicamente , Forboles/efectos adversos , Neoplasias Cutáneas/inducido químicamente , Acetato de Tetradecanoilforbol/efectos adversos , 9,10-Dimetil-1,2-benzantraceno , Animales , Cricetinae , Femenino , Mesocricetus , Acetato de Tetradecanoilforbol/análogos & derivadosRESUMEN
The enhancement of chemical carcinogenesis was demonstrated in vitro in rat tracheal epithelium exposed in organ culture to N-methyl-N'-nitro- N-nitrosoguanidine (MNNG) followed by multiple exposures to 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The explants were exposed to 0 or 0.0001 mu g MNNG per ml for 6 h on days 3 and 6 of culture, and then to 0 or 1.0 mu g TPA per ml for I h on days 9, 15, 21, and 27 of culture. Primary cell cultures were then established from epithelial outgrowths of these explants. Morphologically altered cells were seen in the primary cell cultures derived from MNNG + TPA-exposed explants on an average of 130 days after MNNG exposure. In primary cultures derived from explants exposed to either TPA or MNNG alone, morphologically altered cells were seen at 190 days and 210 days, respectively. No morphologically altered cells were seen in solvent control primary cell cultures. Only cultures containing morphologically altered cells could be repeatedly subcultured. Cell lines established from these cultures were inoculated i.m. into immunosuppressed isogeneic hosts at 150, 200, 250, 310, and 365 days following carcinogen exposure. All five explants exposed to both MNNG and TPA produced at least one cell line which formed carcinomas when inoculated 365 days following exposure, while only two of the five explants produced tumorigenic cell lines in the MNNG-only group. Cell lines from explants exposed to both MNNG and TPA were tumorigenic an average of 90 days earlier than cell lines from explants exposed to MNNG alone. None of the cell lines obtained from the explants exposed only to TPA were tumorigenic. These studies show that, following carcinogen exposure, TPA can enhance the oncogenesis of cultured respiratory tract epithelium in terms of increasing the frequency of transformation and decreasing the time at which transformation could first be observed.