RESUMEN
T-cell protein tyrosine phosphatase (TC-PTP), encoded by Ptpn2, has been shown to function as a tumor suppressor during skin carcinogenesis. In the current study, we generated a novel epidermal-specific TC-PTP-overexpressing (K5HA.Ptpn2) mouse model to show that TC-PTP contributes to the attenuation of chemically induced skin carcinogenesis through the synergistic regulation of STAT1, STAT3, STAT5, and PI3K/AKT signaling. We found overexpression of TC-PTP increased epidermal sensitivity to DMBA-induced apoptosis and it decreased TPA-mediated hyperproliferation, coinciding with reduced epidermal thickness. Inhibition of STAT1, STAT3, STAT5, or AKT reversed the effects of TC-PTP overexpression on epidermal survival and proliferation. Mice overexpressing TC-PTP in the epidermis developed significantly reduced numbers of tumors during skin carcinogenesis and presented a prolonged latency of tumor initiation. Examination of human papillomas and squamous cell carcinomas (SCCs) revealed that TC-PTP expression was significantly reduced and TC-PTP expression was inversely correlated with the increased grade of SCCs. Our findings demonstrate that TC-PTP is a potential therapeutic target for the prevention of human skin cancer given that it is a major negative regulator of oncogenic signaling.
Asunto(s)
Carcinoma de Células Escamosas/enzimología , Epidermis/metabolismo , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Proteínas de Neoplasias/metabolismo , Papiloma/enzimología , Proteína Tirosina Fosfatasa no Receptora Tipo 2/biosíntesis , Transducción de Señal , Neoplasias Cutáneas/enzimología , Animales , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patología , Proliferación Celular , Supervivencia Celular , Epidermis/patología , Humanos , Ratones , Ratones Transgénicos , Proteínas de Neoplasias/genética , Papiloma/genética , Papiloma/patología , Proteína Tirosina Fosfatasa no Receptora Tipo 2/genética , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patologíaRESUMEN
PURPOSE: The protein tyrosine phosphatase PTPN2 dephosphorylates several tyrosine kinases in cancer-related signalling pathways and is thought to be a tumour suppressor. As PTPN2 is not frequently studied in breast cancer, we aimed to explore the role of PTPN2 and the effects of its loss in breast cancer. METHODS: Protein expression and gene copy number of PTPN2 were analysed in a cohort of pre-menopausal breast cancer patients with immunohistochemistry and droplet digital PCR, respectively. PTPN2 was knocked down in three cell lines, representing different breast cancer subtypes, with siRNA transfection. Several proteins related to PTPN2 were analysed with Western blot. RESULTS: Low PTPN2 protein expression was found in 50.2% of the tumours (110/219), gene copy loss in 15.4% (33/214). Low protein expression was associated with a higher relapse rate in patients with Luminal A and HER2-positive tumours, but not triple-negative tumours. In vitro studies further suggested a subtype-specific role of PTPN2. Knockdown of PTPN2 had no effect on the triple-negative cell line, whilst knockdown in MCF7 inhibited phosphorylation of Met and promoted that of Akt. Knockdown in SKBR3 led to increased Met phosphorylation and decreased Erk phosphorylation as well as EGF-mediated STAT3 activation. CONCLUSION: We confirm previous studies showing that the PTPN2 protein is lost in half of the breast cancer cases and gene deletion occurs in 15-18% of the cases. Furthermore, the results suggest that the role of PTPN2 is subtype-related and should be further investigated to assess how this could affect breast cancer prognosis and treatment response.
Asunto(s)
Neoplasias de la Mama/clasificación , Neoplasias de la Mama/enzimología , Proteína Tirosina Fosfatasa no Receptora Tipo 2/metabolismo , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Comunicación Celular , Línea Celular Tumoral , Supervivencia sin Enfermedad , Femenino , Dosificación de Gen , Técnicas de Silenciamiento del Gen , Humanos , Inmunohistoquímica , Células MCF-7 , Pronóstico , Proteína Tirosina Fosfatasa no Receptora Tipo 2/biosíntesis , Proteína Tirosina Fosfatasa no Receptora Tipo 2/deficiencia , Proteína Tirosina Fosfatasa no Receptora Tipo 2/genética , Receptor ErbB-2/biosíntesis , Neoplasias de la Mama Triple Negativas/clasificación , Neoplasias de la Mama Triple Negativas/enzimología , Neoplasias de la Mama Triple Negativas/genética , Neoplasias de la Mama Triple Negativas/patologíaRESUMEN
Beige adipocytes can interconvert between white and brown-like states and switch between energy storage versus expenditure. Here we report that beige adipocyte plasticity is important for feeding-associated changes in energy expenditure and is coordinated by the hypothalamus and the phosphatase TCPTP. A fasting-induced and glucocorticoid-mediated induction of TCPTP, inhibited insulin signaling in AgRP/NPY neurons, repressed the browning of white fat and decreased energy expenditure. Conversely feeding reduced hypothalamic TCPTP, to increase AgRP/NPY neuronal insulin signaling, white adipose tissue browning and energy expenditure. The feeding-induced repression of hypothalamic TCPTP was defective in obesity. Mice lacking TCPTP in AgRP/NPY neurons were resistant to diet-induced obesity and had increased beige fat activity and energy expenditure. The deletion of hypothalamic TCPTP in obesity restored feeding-induced browning and increased energy expenditure to promote weight loss. Our studies define a hypothalamic switch that coordinates energy expenditure with feeding for the maintenance of energy balance.
