Ribonuclease MCPiP1 contributes to the loss of micro-RNA-200 family members in pancreatic cancer cells
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Françoise Boudouresque1, Carole Siret1,2, Aurélie Dobric1,3, Françoise Silvy1,3, Philippe Soubeyran3, Juan Iovanna3, Dominique Lombardo1 and Yolande Berthois1,3
1Aix-Marseille Univ, INSERM UMR 911, CRO2, Marseille, France
2Aix-Marseille Univ, CNRS, INSERM, CIML Marseille, France
3Present address: Aix-Marseille University, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Pancreatic Cancer Team, Marseille, France
Yolande Berthois, email: [email protected]
Keywords: pancreatic cancer; micro-RNA-200; MCPiP1; dicer1
Received: April 04, 2018 Accepted: October 25, 2018 Published: November 13, 2018
The microRNA-200 (miR-200) family is frequently down-regulated in tumors, including pancreatic adenocarcinomas (PDACs). In this study we have examined the mechanisms involved in the loss of miR-200s in tumoral pancreatic cells. Whereas miR-200 gene promoters appear methylated in mature miR-200 deficient cell lines, miR-200 precursors are detected in nuclear but not cytoplasmic compartment of these cells, indicating that promoter hypermethylation is not sufficient to explain the deficit of mature miR-200s. The ribonuclease Monocyte Chemotactic Protein-induced Protein-1 (MCPiP1) may counteract Dicer1 in miRNA maturation process. MCPiP1/Dicer1 mRNA and protein ratios appear higher in miR-200 deficient compared to miR-200 proficient cells, suggesting that MCPiP1 may compete with Dicer1 in mature miR-200 deficient cells. Inhibition of MCPiP1 allows the detection of miR-200 precursors in cytoplasm of miR-200 deficient cells, confirming its involvement in the loss of miR-200s. Also, reversion of MCPiP1/Dicer1 ratio by over-expression of Dicer1 in miR-200 deficient cells leads to the recovery of mature miR-200s. Finally, whereas human malignant pancreatic tissues (PDACs) express lower miR-200 levels than non malignant tissues (non-MPDs), MCPiP1/Dicer1 ratio appears higher in PDACs, when compared to non-MPDs, supporting the hypothesis that MCPiP1/Dicer1 ratio is determinant in regulating miR-200 maturation process in a subset of tumoral pancreatic cells.
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