Figure 2.
Suppression of pituitary tumor cell growth by DRD5 activation in vitro and in vivo. (A) DRD5 agonist SKF83959 treatment in GH3 cells induced apoptosis. Left: After 48-h treatment at 12.5, 25, and 50 μM, the apoptotic cell population was 8.4% (p < 0.05), 30.6% (p < 0.001), and 49.5% (p < 0.001), respectively. Middle: CASP3 and CASP7 activity fold was 2.1 (p < 0.05), 4.3 (p < 0.001), and 8.5 (p < 0.001), respectively. Right: Treatment with SKF83959 increased cleaved CASP3 and CASP8. (B) In colony formation assays, SKF83959 and CAB treatment resulted in inhibition of cell colonies by 59% and 63%, respectively (p < 0.001). (C) Drd5 KD in GH3 cells partially abolished SKF83959-induced growth suppression. At 48 h and 72 h, Drd5 KD increased viable cell count from 62% to 92% and from 28% to 68%, respectively (p < 0.001). (D) Drd5 KD in GH3 cells reduced the expression of c-CASP3 and c-CASP8 induced by SKF83959. (E) DRD5 agonist SKF83959 suppressed GH3 tumor growth in nude mice. (F) Comparison of GH3 tumors from mice treated with control vehicle and with SKF83959 at d 11 of drug administration. (G) Tumor weights from mice treated with control vehicle and with SKF83959 at day 11 of drug administration. The average ratio of tumor:nude mice weight from the control group and from the SKF83959-treated group was 46 ± 13.1mg/g and 8 ± 2.5mg/g, respectively. NC, nonspecific negative control siRNA; *, p < 0.05; **, p < 0.01; ***, p < 0.001.