RESUMO
Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignancies with very poor prognosis due to its broad resistance to chemotherapy. Our previous study showed that integrin ß1 expression is upregulated in PDAC and confers gemcitabine resistance in PDAC cells via the signaling pathway including Cdc42 and AKT activation. But the accurate signal transductions are not clear. Here, we aimed to illuminate the signal transductions of integrin ß1 in the acquisition of gemcitabine resistance in PDAC. Drug-resistance (DR) cells from AsPC-1 parent cell line (PCL) were selected. Integrin ß1 expression was determined using western blot assay. Changes in drug response and the activity of phosphatidylinositol 3-kinase (PI3K) signaling after knockdown of integrin ß1, Cdc42 or p110ß were evaluated using MTT, cleaved caspase-3 immunofluorescence and western blot assay. Western blot assays also detected the variations in Cdc42 activity and p110ß expression after integrin ß1 knockdown. The interaction between Cdc42 and p110ß was determined by Glutathione S-transferase (GST) pull-down assay. The results showed that integrin ß1 expression was upregulated in DR-AsPC-1â¯cells, and integrin ß1 knockdown significantly decreased the activity of Cdc42, a target molecule of integrin ß1, and p110ß expression. Knockdown of anyone of integrin ß1, Cdc42 and p110ß inhibited the activity of PI3K signaling, and sensitized DR-AsPC-1â¯cells to gemcitabine. GST pull-down assay showed that GTP-Cdc42 interacted with p110ß. Collectively, these data indicated that integrin ß1 promoted gemcitabine resistance in PDAC through Cdc42 activation of PI3K p110ß signaling. In vivo experiments also confirmed this conclusion. These findings contribute to a better understanding the molecular mechanism of chemoresistance and facilitate the development of more targeted and effective treatment strategy for PDAC.
Assuntos
Classe Ia de Fosfatidilinositol 3-Quinase/metabolismo , Desoxicitidina/análogos & derivados , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Integrina beta1/metabolismo , Neoplasias Pancreáticas/tratamento farmacológico , Proteína cdc42 de Ligação ao GTP/metabolismo , Animais , Antimetabólitos Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Desoxicitidina/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Humanos , Integrina beta1/genética , Camundongos Endogâmicos BALB C , Camundongos Nus , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Interferência de RNA , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto , GencitabinaRESUMO
Glioblastoma multiforme (GBM) is the most malignant primary brain tumor with a median survival of approximately 14 months. Despite aggressive treatment of surgical resection, chemotherapy and radiation therapy, only 3-5% of GBM patients survive more than 3 years. Contributing to this poor therapeutic response, it is believed that GBM contains both intrinsic and acquired mechanisms of resistance, including resistance to radiation therapy. In order to define novel mediators of radiation resistance, we conducted a functional knockdown screen, and identified the immunoglobulin superfamily protein, PTGFRN. In GBM, PTGFRN is found to be overexpressed and to correlate with poor survival. Reducing PTGFRN expression radiosensitizes GBM cells and potently decreases the rate of cell proliferation and tumor growth. Further, PTGFRN inhibition results in significant reduction of PI3K p110ß and phosphorylated AKT, due to instability of p110ß. Additionally, PTGFRN inhibition decreases nuclear p110ß leading to decreased DNA damage sensing and DNA damage repair. Therefore overexpression of PTGFRN in glioblastoma promotes AKT-driven survival signaling and tumor growth, as well as increased DNA repair signaling. These findings suggest PTGFRN is a potential signaling hub for aggressiveness in GBM.