Figure 7.

KRAS and STAT5B mediate the effects of miR-134 and miR-134 mediates the effects of RTKs on KRAS, STAT5B, cell proliferation, and in vivo xenograft growth. (a) Immunoblots showing expressions of KRAS and STAT5B in GBM cells stably transfected with respective cDNAs lacking the 3′UTR sequences (upper panel), and lack of inhibition of KRAS and STAT5B expressions by miR-134 in the same cells (lower panel). (b) Proliferation assay showing the effects of miR-134 in the clones overexpressing KRAS and STAT5B described in (a). The results show rescue of the effects of miR-134 in the cells. (c) Immunoblots and immunoblot quantifications of KRAS or STAT5B in response to HGF treatment with or without miR-134 overexpression. The data show that miR-134 partially rescues the effects of HGF on KRAS and STAT5B. (d) KRAS expressing stable cells (U87-KRAS) or U87-Control were transfected with pre-miR-134 or pre-miR-con and implanted into the brains of immunodeficient mice (n=5) and animal survival was assessed. The results show that miR-134 significantly enhances animal survival in control but not in KRAS-overexpressing tumor-bearing animals (left panel). *P<0.05. The right panel shows representative MRIs with tumors at 2 weeks post implantation. (e–g) Proliferation assay of GBM cells in response to RTK inhibitors, Crizotinib (e), Erlotinib (f), and Imatinib (g), with or without anti-miR-134 pre-treatment. The data show that anit-miR-134 partially rescues the effects of the inhibitors on cell proliferation. *P<0.05