RESUMO
Pancreatic cancer is a leading cause of cancer-related deaths in Western societies. This poor prognosis is due to chemotherapeutic drug resistance and metastatic spread. Evidence suggests that microtubule proteins namely, ß-tubulins are dysregulated in tumor cells and are involved in regulating chemosensitivity. However, the role of ß-tubulins in pancreatic cancer are unknown. We measured the expression of different ß-tubulin isotypes in pancreatic adenocarcinoma tissue and pancreatic cancer cells. Next, we used RNAi to silence ßIII-tubulin expression in pancreatic cancer cells, and measured cell growth in the absence and presence of chemotherapeutic drugs. Finally, we assessed the role of ßIII-tubulin in regulating tumor growth and metastases using an orthotopic pancreatic cancer mouse model. We found that ßIII-tubulin is highly expressed in pancreatic adenocarcinoma tissue and pancreatic cancer cells. Further, we demonstrated that silencing ßIII-tubulin expression reduced pancreatic cancer cell growth and tumorigenic potential in the absence and presence of chemotherapeutic drugs. Finally, we demonstrated that suppression of ßIII-tubulin reduced tumor growth and metastases in vivo. Our novel data demonstrate that ßIII-tubulin is a key player in promoting pancreatic cancer growth and survival, and silencing its expression may be a potential therapeutic strategy to increase the long-term survival of pancreatic cancer patients.
Assuntos
Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias Pancreáticas/genética , Interferência de RNA , Tubulina (Proteína)/genética , Animais , Anoikis/genética , Apoptose/genética , Western Blotting , Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Imuno-Histoquímica , Camundongos Endogâmicos BALB C , Camundongos Nus , Metástase Neoplásica , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Terapêutica com RNAi , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: Neural invasion (NI) is a histopathologic feature of colon cancer that receives little consideration. Therefore, we conducted a morphologic and functional characterization of NI in colon cancer. EXPERIMENTAL DESIGN: NI was investigated in 673 patients with colon cancer. Localization and severity of NI was determined and related to patient's prognosis and survival. The neuro-affinity of colon cancer cells (HT29, HCT-116, SW620, and DLD-1) was compared with pancreatic cancer (T3M4 and SU86.86) and rectal cancer cells (CMT-93) in the in vitro three-dimensional (3D)-neural-migration assay and analyzed via live-cell imaging. Immunoreactivity of the neuroplasticity marker GAP-43, and the neurotrophic-chemoattractant factors Artemin and nerve growth factor (NGF), was quantified in colon cancer and pancreatic cancer nerves. Dorsal root ganglia of newborn rats were exposed to supernatants of colon cancer, rectal cancer, and pancreatic cancer cells and neurite density was determined. RESULTS: NI was detected in 210 of 673 patients (31.2%). Although increasing NI severity scores were associated with a significantly poorer survival, presence of NI was not an independent prognostic factor in colon cancer. In the 3D migration assay, colon cancer and rectal cancer cells showed much less neurite-targeted migration when compared with pancreatic cancer cells. Supernatants of pancreatic cancer and rectal cancer cells induced a much higher neurite density than those of colon cancer cells. Accordingly, NGF, Artemin, and GAP-43 were much more pronounced in nerves in pancreatic cancer than in colon cancer. CONCLUSION: NI is not an independent prognostic factor in colon cancer. The lack of a considerable biologic affinity between colon cancer cells and neurons, the low expression profile of colonic nerves for chemoattractant molecules, and the absence of a major neuroplasticity in colon cancer may explain the low prevalence and impact of NI in colon cancer.