MADD/DENN splice variant of the IG20 gene is necessary and sufficient for cancer cell survival
MADD/DENN splice variant of the IG20 gene is necessary and sufficient for cancer cell survival
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DOI：
10.1038/sj.onc.1209650
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发表时间：
2006-10-12
期刊：
影响因子：
8
通讯作者：
Prabhakar, B. S.
中科院分区：
文献类型：
--
作者：
Mulherkar, N.;Ramaswamy, M.;Prabhakar, B. S.
IG20基因在人类肿瘤和癌细胞中高表达，编码至少4个剪接变异体，即IG20pa、MADD、IG20-SV2和DENNSV。早期的功能获得研究表明，IG20SVs可以发挥多种功能，并在细胞增殖和凋亡中发挥关键作用。外源性IG20pa和Denn-SV的表达分别使细胞对诱导的凋亡敏感或抵抗，而MADD和IG20-SV2的表达没有明显的作用。为了了解IG20-SVS在生理上更相关的系统中的对比作用，我们表达了外显子特异的小发夹RNA(ShRNAs)来选择性地击倒特定的IG20-SVS。与早期的研究一致，所有IG20-SVS的敲除导致HeLa和PA-1细胞的自发凋亡。此外，我们明确地证明，MADD基因的敲除可以使细胞对自发凋亡易感，但对细胞增殖、集落大小或细胞周期进程没有明显影响。此外，在缺乏内源性IG20-SVS的情况下，单独表达MADD而不是Denn-SV足以防止自发凋亡。我们的结果表明shRNAs用于选择性地敲除特定的IG20-SVS及其在癌症中的潜在治疗价值。此外，他们还证明了MADD本身对于癌细胞存活是充分和必要的。
The IG20 gene is overexpressed in human tumors and cancer cell lines, and encodes at least four splice variants (SVs) namely, IG20pa, MADD, IG20-SV2 and DENNSV. Earlier, gain-of-function studies showed that IG20SVs can exhibit diverse functions and play a critical role in cell proliferation and apoptosis. Expression of exogenous IG20pa or DENN-SV rendered cells either susceptible or resistant to induced apoptosis, respectively, whereas MADD and IG20-SV2 had no apparent effect. In order to understand the contrasting effects of the IG20-SVs in a physiologically more relevant system, we expressed exon-specific small hairpin RNAs (shRNAs) to selectively knockdown specific IG20-SVs. Consistent with an earlier study, knockdown of all IG20-SVs resulted in spontaneous apoptosis of HeLa and PA-1 cells. In addition, we unambiguously demonstrated that knockdown of MADD can render cells susceptible to spontaneous apoptosis but had no discernible effect on cell proliferation, colony size or cell cycle progression. Moreover, expression of MADD alone, and not DENN-SV, in the absence of endogenous IG20-SVs was sufficient to prevent spontaneous apoptosis. Our results show the utility of shRNAs for selective knockdown of particular IG20-SVs and their potential therapeutic value in cancer. Further, they demonstrate that MADD alone is sufficient and necessary for cancer cell survival.