RESUMO
Aberrant expression of microRNAs (miRs) has been shown to play a critical role in the pathogenesis and progression of tumors. microRNA-219-5p (miR-219-5p) has been reported to be abnormally expressed in some types of human tumors. However, the mechanism between miR-219-5p and colorectal cancer (CRC) metastasis remains unclear. In the present study, miR-219-5p was found to be downregulated in CRC tissue compared with matched normal tissue. Through luciferase reporter assay, we demonstrated lymphoid enhancer-binding factor 1 (LEF1) as a direct target of miR-219-5p. Overexpression of miR-219-5p could inhibit motility, migration and invasion of CRC cells, and inhibit epithelial-mesenchymal transition (EMT). Furthermore, silencing LEF1 phenocopied this metastasis-suppressive function. The recovery experiment showed that re-expression of LEF1 rescued this suppressive effect on tumor metastasis and reversed the expression of EMT markers caused by miR-219-5p. Additionally, we demonstrated that miR-219-5p exerted this tumor-suppressive function by blocking activation of the AKT and ERK pathways. Finally, a nude mice experiment showed that miR-219-5p reduced the lung metastasis ability of CRC cells. Taken together, our findings indicate that miR-219-5p inhibits metastasis and EMT of CRC by targeting LEF1 and suppressing the AKT and ERK pathways, which may provide a new antitumor strategy to delay CRC metastasis.
Assuntos
Neoplasias Colorretais/patologia , Transição Epitelial-Mesenquimal , Neoplasias Pulmonares/secundário , Fator 1 de Ligação ao Facilitador Linfoide/genética , MicroRNAs/genética , Regiões 3' não Traduzidas , Animais , Células CACO-2 , Linhagem Celular Tumoral , Neoplasias Colorretais/genética , Regulação para Baixo , Feminino , Regulação Neoplásica da Expressão Gênica , Células HCT116 , Células HT29 , Humanos , Neoplasias Pulmonares/genética , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos , Camundongos Nus , Transplante de NeoplasiasRESUMO
Cancer stem cell theory indicates cancer stem cells are the key to promote tumor invasion and metastasis. Studies showed that BMI-1 could promote self-renew, differentiation and tumor formation of CSCs and invasion/metastasis of human cancer. However, whether BMI-1 could regulate invasion and metastasis ability of CSCs is still unclear. In our study, we found that up-regulated expression of BMI-1 was associated with tumor invasion, metastasis and poor survival of pancreatic cancer patients. CD133+ cells were obtained by using magnetic cell sorting and identified of CSCs properties such as self-renew, multi-differentiation and tumor formation ability. Then, we found that BMI-1 expression was up-regulated in pancreatic cancer stem cells. Knockdown of BMI-1 expression attenuated invasion ability of pancreatic cancer stem cells in Transwell system and liver metastasis capacity in nude mice which were injected CSCs through the caudal vein. We are the first to reveal that BMI-1 could promote invasion and metastasis ability of pancreatic cancer stem cells. Finally, we identified that BMI-1 expression activating PI3K/AKT singing pathway by negative regulating PTEN was the main mechanism of promoting invasion and metastasis ability of pancreatic CSCs. In summary, our findings indicate that BMI-1 could be used as the therapeutic target to inhibiting CSCs-mediated pancreatic cancer metastasis.