Cell-type specific and non-redundant anti-proliferative effects of shRNA-mediated Galpha12- and Galpha13 knockdown in lung cancer cell lines

Abstract

In small cell lung cancer cells, various autocrine stimuli lead to the parallel activation of Gq/11 and G 12/13 proteins. The contribution of the Gq/11-PLC- β cascade to the mitogenic effects in SCLC cells is well established, but the relevance of G 12/13 signaling is less explored. While in prostate and breast cancer, G 12/13 activation has been shown previously to promote invasiveness without being involved in cellular proliferation, previous data from our group indicate anti-proliferative effects of G 12/13 knockdown in small cell lung cancer (SCLC) cells. To further investigate the role of G 12/13 -dependent signaling in lung tumor cells, we employed shRNA-mediated targeting of G α 12 , G α 13 , or both, in SCLC and NSCLC cell lines. Lentiviral expression of shRNAs resulted in specific G α 12 and G α 13 knockdown. Of note, upon single knockdown of one family member, no counter-upregulation of the other one was observed. Interestingly, inhibition of proliferation was cell line dependent. In cell lines where knock-down led to antiproliferation, single knockdown of either G α 12 or G α 13 was sufficient to impair proliferation and double knockdown of G α 12 and G α 13 tended not to fur ther increase anti-proliferative effects. Likewise, when single knockdown was insufficient for an inhibition of proliferation, no effects were observed in double knockdowns. Taken together, these findings indicate that both G α 12 and G α 13 affect cellular proliferation individually and interference with one family member is sufficient for anti-tumor effects.