PURPOSE: In small cell lung cancer cells (SCLC), various autocrine stimuli lead to the parallel activation of G(q/11) and G(12/13) proteins. Although the contribution of the G(q/11)-phospholipase C-beta cascade to mitogenic effects in SCLC cells is well established, the relevance of G(12/13) signaling is still elusive. In other tumor entities, G(12/13) activation promotes invasiveness without affecting cellular proliferation. Here, we investigate the role of G(12/13)-dependent signaling in SCLC. EXPERIMENTAL DESIGN: We used small hairpin RNA-mediated targeting of G(alpha)(12), G(alpha)(13), or both in H69 and H209 cells and analyzed the effects of G(alpha)(12) and/or G(alpha)(13) knockdown on tumor cells in vitro, tumor growth in vivo, and mitogen-activated protein kinase (MAPK) activation. RESULTS: Lentiviral expression of small hairpin RNAs resulted in robust and specific G(alpha)(12) and G(alpha)(13) knockdown as well as markedly inhibited proliferation, colony formation, and bradykinin-promoted stimulation of cell growth. Analyzing the activation status of all three major MAPK families revealed nonredundant functions of G(alpha)(12) and G(alpha)(13) in SCLC and a marked p42/p44 activation upon G(alpha)(12)/G(alpha)(13) knockdown. In a s.c. tumor xenograft mouse model, G(alpha)(12) or G(alpha)(13) downregulation led to decreased tumor growth due to reduced tumor cell proliferation. More importantly, G(alpha)(12)/G(alpha)(13) double knockdown completely abolished H69 tumorigenicity in mice. CONCLUSIONS: G(alpha)(12) and G(alpha)13) exert a complex pattern of nonredundant effects in SCLC, and in contrast to other tumor types, SCLC cell proliferation in vitro and tumorigenicity in vivo critically depend on G(12/13) signaling. Due to the complete abolishment of tumorgenicity in our study, RNAi-mediated double knockdown may provide a promising new avenue in SCLC treatment.
PURPOSE: In small cell lung cancer cells (SCLC), various autocrine stimuli lead to the parallel activation of G(q/11) and G(12/13) proteins. Although the contribution of the G(q/11)-phospholipase C-beta cascade to mitogenic effects in SCLC cells is well established, the relevance of G(12/13) signaling is still elusive. In other tumor entities, G(12/13) activation promotes invasiveness without affecting cellular proliferation. Here, we investigate the role of G(12/13)-dependent signaling in SCLC. EXPERIMENTAL DESIGN: We used small hairpin RNA-mediated targeting of G(alpha)(12), G(alpha)(13), or both in H69 and H209 cells and analyzed the effects of G(alpha)(12) and/or G(alpha)(13) knockdown on tumor cells in vitro, tumor growth in vivo, and mitogen-activated protein kinase (MAPK) activation. RESULTS: Lentiviral expression of small hairpin RNAs resulted in robust and specific G(alpha)(12) and G(alpha)(13) knockdown as well as markedly inhibited proliferation, colony formation, and bradykinin-promoted stimulation of cell growth. Analyzing the activation status of all three major MAPK families revealed nonredundant functions of G(alpha)(12) and G(alpha)(13) in SCLC and a marked p42/p44 activation upon G(alpha)(12)/G(alpha)(13) knockdown. In a s.c. tumor xenograft mouse model, G(alpha)(12) or G(alpha)(13) downregulation led to decreased tumor growth due to reduced tumor cell proliferation. More importantly, G(alpha)(12)/G(alpha)(13) double knockdown completely abolished H69 tumorigenicity in mice. CONCLUSIONS: G(alpha)(12) and G(alpha)13) exert a complex pattern of nonredundant effects in SCLC, and in contrast to other tumor types, SCLC cell proliferation in vitro and tumorigenicity in vivo critically depend on G(12/13) signaling. Due to the complete abolishment of tumorgenicity in our study, RNAi-mediated double knockdown may provide a promising new avenue in SCLC treatment.
Authors: Y M Yang; W H Lee; C G Lee; J An; E-S Kim; S H Kim; S-K Lee; C H Lee; D N Dhanasekaran; A Moon; S Hwang; S J Lee; J-W Park; K M Kim; S G Kim Journal: Oncogene Date: 2014-07-28 Impact factor: 9.867
Authors: Ji Hee Ha; Rohini Gomathinayagam; Mingda Yan; Muralidharan Jayaraman; Rajagopal Ramesh; Danny N Dhanasekaran Journal: Genes Cancer Date: 2015-07