Wong Carmen Chak-Lui, Wong Chun-Ming, Tung Edmund Kwok-Kwan, Man Kwan, Ng Irene Oi-Lin
Department of Pathology, Liver Cancer and Hepatitis Research Laboratory, The University of Hong Kong, Hong Kong.
Hepatology. 2009 May;49(5):1583-94. doi: 10.1002/hep.22836.
Deregulation of Rho family small guanosine triphosphatases has been implicated in human carcinogenesis. Rho-kinases are downstream effectors of Rho guanosine triphosphatases in the regulation of cytoskeletal reorganization and cell motility. However, their functions in human cancers remain elusive. In this study, we aimed to investigate the role of Rho-kinases in hepatocellular carcinoma (HCC) tumor progression and invasion. We first examined the expression of the two Rho-kinases (ROCK1 and ROCK2) in human HCC, and found that ROCK2 was frequently overexpressed in primary HCCs (22/41 [53.66%]). Clinico-pathological analysis revealed that overexpression of ROCK2 was significantly associated with the presence of tumor microsatellite formation (P = 0.005), suggesting that deregulation of ROCK2 may contribute to the intrahepatic metastasis of HCC. Consistently, we demonstrated that stable overexpression of ROCK2 significantly enhanced cell motility and invasiveness in HCC cells. Conversely, stable knockdown of ROCK2 by short hairpin RNA approach remarkably reduced HCC cell migration and invasion. Moreover, orthotopic liver xenograft models provided further support that stable knockdown of ROCK2 suppressed HCC invasion in vivo. Stable knockdown of ROCK2 in HCC cells significantly inhibited Golgi reorientation, myosin phosphatase phosphorylation, and formations of stress fibers, filopodia, and lamellipodia; these molecular and cellular events are crucial for cell motility and cancer invasion.
Our results indicate that ROCK2 was overexpressed in human HCCs, and this overexpression was associated with a more aggressive biological behavior. Our findings also demonstrate that ROCK2 played a significant role in regulating cytoskeletal events and contributed to the invasion of HCC.
Rho家族小GTP酶的失调与人类致癌作用有关。Rho激酶是Rho GTP酶在细胞骨架重组和细胞运动调节中的下游效应器。然而，它们在人类癌症中的功能仍不清楚。在本研究中，我们旨在研究Rho激酶在肝细胞癌（HCC）肿瘤进展和侵袭中的作用。我们首先检测了两种Rho激酶（ROCK1和ROCK2）在人类HCC中的表达，发现ROCK2在原发性HCC中经常过度表达（22/41 [53.66%]）。临床病理分析显示，ROCK2的过度表达与肿瘤微卫星形成的存在显著相关（P = 0.005），这表明ROCK2的失调可能促成HCC的肝内转移。一致地，我们证明ROCK2的稳定过表达显著增强了HCC细胞的运动性和侵袭性。相反，通过短发夹RNA方法稳定敲低ROCK2可显著降低HCC细胞的迁移和侵袭。此外，原位肝异种移植模型进一步支持了ROCK2的稳定敲低在体内抑制HCC侵袭。在HCC细胞中稳定敲低ROCK2显著抑制了高尔基体重新定向、肌球蛋白磷酸酶磷酸化以及应力纤维、丝状伪足和片状伪足的形成；这些分子和细胞事件对于细胞运动和癌症侵袭至关重要。
我们的结果表明，ROCK2在人类HCC中过度表达，这种过度表达与更具侵袭性的生物学行为相关。我们的研究结果还表明，ROCK2在调节细胞骨架事件中起重要作用，并促成了HCC的侵袭。
