Upregulation of miR-150* and miR-630 Induces Apoptosis in Pancreatic Cancer Cells by Targeting IGF-1R

MicroRNAs have been implicated in many critical cellular processes including apoptosis. We have previously found that apoptosis in pancreatic cancer cells was induced by adamantyl retinoid-related (ARR) molecule 3-Cl-AHPC. Here we report that 3-Cl-AHPC-dependent apoptosis involves regulating a number of microRNAs including miR-150* and miR-630. 3-Cl-AHPC stimulated miR-150* expression and caused decreased expression of c-Myb and IGF-1R in the pancreatic cancer cells. 3-Cl-AHPC-mediated reduction of c-Myb resulted in diminished binding of c-Myb with IGF-1R and Bcl-2 promoters, thereby causing repression of their transcription and protein expression. Over-expression of miR-150* also resulted in diminished levels of c-Myb and Bcl-2 proteins. Furthermore, the addition of the miRNA inhibitor 2'-O-methylated miR-150 blocked 3-Cl-AHPC-mediated increase in miR-150* levels and abrogated loss of c-Myb protein. Knockdown of c-Myb in PANC-1 cells resulted in enhanced apoptosis both in the presence or absence of 3-Cl-AHPC confirming the anti-apoptotic property of c-Myb. Overexpression of miR-630 also induced apoptosis in the pancreatic cancer cells and inhibited target protein IGF-1R mRNA and protein expression. Together these results implicate key roles for miR-150* and miR-630 and their targeting of IGF-1R to promote apoptosis in pancreatic cancer cells.