Figure 4.

MiR-17 or miR-20a inhibits HIF-1α-triggered growth arrest and granulocytic differentiation of U937 cells. (a) Validation of overexpression of miR-17 and miR-20a in U937T^empty and U937T^HIF-1α cells using northern blot. The relative amount of each miRNA was normalized to U6 snRNA. The U937T^empty and U937T^HIF-1α cells were respectively infected with empty retrovirus vector (p-Mig), miR-17 or miR-20a-expressing retrovirus and then grouped as U937T^empty-p-Mig, U937T^empty-miR-17, U937T^{empty-miR-20α} or U937T^{HIF-1α-p-Mig}, U937T^{HIF-1α-miR-17}, and U937T^{HIF-1α-miR-20α}, respectively. (b–f) The indicated cell lines were grown for the various days after tetracycline removal. Then, the proliferation and differentiation were measured as below: (b) viable cell numbers of the above six transformants, (c) cell-cycle distribution of the three U937T^HIF-1α transformants, (d) CD11c-positive cells of the three U937T^HIF-1α transformants (%), (e) cell morphology of the three U937T^HIF-1α transformants, and (f) NBT reduction of the six transformants (6 days after tetracycline removal). The symbols * and # represented P<0.05 compared respectively with U937T^{HIF-1α-p-Mig} cells