Organ Shawna L, Hai Josephine, Radulovich Nikolina, Marshall Christopher B, Leung Lisa, Sasazuki Takehiko, Shirasawa Senji, Zhu Chang-Qi, Navab Roya, Ikura Mitsuhiko, Tsao Ming-Sound
Princess Margaret Cancer Centre, Toronto, Ontario, Canada ; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
Princess Margaret Cancer Centre, Toronto, Ontario, Canada ; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
PLoS One. 2014 Jan 21;9(1):e86103. doi: 10.1371/journal.pone.0086103. eCollection 2014.
KRAS is mutated in ∼40% of colorectal cancer (CRC), and there are limited effective treatments for advanced KRAS mutant CRC. Therefore, it is crucial that downstream mediators of oncogenic KRAS continue to be studied. We identified p190RhoGAP as being phosphorylated in the DLD1 CRC cell line, which expresses a heterozygous KRAS G13D allele, and not in DKO4 in which the mutant allele has been deleted by somatic recombination. We found that a ubiquitous binding partner of p190RhoGAP, p120RasGAP (RasGAP), is expressed in much lower levels in DKO4 cells compared to DLD1, and this expression is regulated by KRAS. Rescue of RasGAP expression in DKO4 rescued Rho pathway activation and partially rescued tumorigenicity in DKO4 cells, indicating that the combination of mutant KRAS and RasGAP expression is crucial to these phenotypes. We conclude that RasGAP is an important effector of mutant KRAS in CRC.
在约40%的结直肠癌（CRC）中，KRAS发生突变，而对于晚期KRAS突变型CRC，有效的治疗方法有限。因此，继续研究致癌性KRAS的下游介质至关重要。我们发现p190RhoGAP在表达杂合KRAS G13D等位基因的DLD1 CRC细胞系中发生磷酸化，而在通过体细胞重组删除了突变等位基因的DKO4细胞系中未发生磷酸化。我们发现，p190RhoGAP的一个普遍存在的结合伴侣p120RasGAP（RasGAP）在DKO4细胞中的表达水平远低于DLD1细胞，且这种表达受KRAS调控。在DKO4细胞中恢复RasGAP的表达可挽救Rho途径的激活，并部分挽救DKO4细胞的致瘤性，这表明突变型KRAS和RasGAP表达的组合对这些表型至关重要。我们得出结论，RasGAP是CRC中突变型KRAS的重要效应物。
