Rho相關(guān)激酶ROCK1和ROCK2腫瘤細(xì)胞遷移和侵襲的關(guān)鍵,，這表明它們可能是有用的治療靶點(diǎn),。在這項(xiàng)研究中，研究者發(fā)現(xiàn)一個(gè)強(qiáng)有力的ROCK1和ROCK2的小分子抑制劑RKI-1447,。
RKI-1447/ROCK1復(fù)合物晶體結(jié)構(gòu)顯示,，RKI-1447是一個(gè)I型激酶抑制劑，通過(guò)鉸鏈區(qū)和DFG結(jié)構(gòu)域的相互作用與ATP結(jié)合位點(diǎn)相結(jié)合,。 在人類癌細(xì)胞中,，RKI-1447抑制ROCK底物MLC-2和 MYPT-1的磷酸化，但在高達(dá)10μM的藥物濃度下,，不影響AKT,，MEK和S6激酶的磷酸化水平的。
RKI-1447高度選擇性抑制LPA刺激引發(fā)的,，ROCK介導(dǎo)的細(xì)胞骨架重新組織（肌動(dòng)蛋白應(yīng)力纖維的形成）,，但并不影響分別發(fā)生于PDGF及血管緩激肽刺激后的，PAK介導(dǎo)的板狀偽足和絲狀偽足形成,。 RKI-1447抑制乳腺癌細(xì)胞遷移,，侵襲和不依賴于錨定的腫瘤生長(zhǎng)。 相反,，類似物RKI-1313,，在體外實(shí)驗(yàn)中對(duì)ROCK底物的磷酸化水平，腫瘤細(xì)胞遷移,，入侵或不依賴于錨定的生長(zhǎng)影響都不大,。最后RKI-1447可高度有效抑制乳腺腫瘤在轉(zhuǎn)基因小鼠模型中的生長(zhǎng)。
總之,，本研究結(jié)果證實(shí),，作為強(qiáng)有力的和有選擇性的ROCK抑制劑，RKI-1447可發(fā)揮顯著的抗侵襲和抗腫瘤活性,，并為進(jìn)一步的臨床驗(yàn)證打下了基礎(chǔ),。（生物谷bioon.com）
doi:10.1016/j.cell.2011.10.017
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RKI-1447 is a potent inhibitor of the Rho-associated ROCK kinases with anti-invasive and anti-tumor activities in breast cancer
Ronil A. Patel1,Kara D. Forinash1,Roberta Pireddu2,Ying Sun1,Nan Sun1,Mathew P. Martin1,Ernst Schonbrunn1,Nicholas J. Lawrence1, andSaid M. Sebti3,*
The Rho-associated kinases ROCK1 and ROCK2 are critical for cancer cell migration and invasion, suggesting they may be useful therapeutic targets. In this study, we describe the discovery and development of RKI-1447, a potent small molecule inhibitor of ROCK1 and ROCK2. Crystal structures of the RKI-1447/ROCK1 complex revealed that RKI-1447 is a Type I kinase inhibitor that binds the ATP binding site through interactions with the hinge region and the DFG motif. RKI-1447 suppressed phosphorylation of the ROCK substrates MLC-2 and MYPT-1 in human cancer cells, but had no effect on the phosphorylation levels of the AKT, MEK and S6 kinase at concentrations as high as10 μM. RKI-1447 was also highly selective at inhibiting ROCK-mediated cytoskeleton re-organization (actin stress fiber formation) following LPA stimulation, but does not affect PAK-meditated lamellipodia and filopodia formation following PDGF and Bradykinin stimulation, respectively. RKI-1447 inhibited migration, invasion and anchorage-independent tumor growth of breast cancer cells. In contrast, RKI-1313, a much weaker analog in vitro, had little effect on the phosphorylation levels of ROCK substrates, migration, invasion or anchorage-independent growth. Lastly RKI-1447 was highly effective at inhibiting the outgrowth of mammary tumors in a transgenic mouse model. In summary, our findings establish RKI-1447 as a potent and selective ROCK inhibitor with significant anti-invasive and anti-tumor activities and offer a preclinical proof-of-concept that justify further examination of RKI-1447 suitability as a potential clinical candidate.
