Department of Surgery, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China.
Int J Cancer. 2010 Aug 15;127(4):859-72. doi: 10.1002/ijc.25105.
We previously demonstrated that the overexpression of homeoprotein Six1 in hepatocellular carcinoma (HCC) patients is associated with venous infiltration, advanced pathologic tumor metastasis (pTNM) stage and poor overall survival rate (Ng et al. Br J Cancer 2006;95:1050-5). In this study, short hairpin RNA (shRNA) interference approach was used to suppress the expression of Six1 in a metastatic HCC cell line MHCC97L. Stable transfectant MHCC97L-shSix1 carrying Six1-specific shRNA plasmid was established to downregulate Six1 expression to about 40% when compared with MHCC97L-Control. In vitro functional assays demonstrated that the growth rate and proliferation ability of MHCC97L-shSix1 cells were markedly decreased. Moreover, significant decrease of cell motility and invasiveness were observed in MHCC97L-shSix1 cells. Data from in vivo xenograft tumorigenesis model demonstrated that the size of tumor in MHCC97L-shSix1 group was dramatically reduced. Experimental and spontaneous metastasis models indicated that targeting Six1 suppression noticeably reduced the pulmonary metastasis in MHCC97L-shSix1 group. To identify Six1-regulated targets, cDNA microarray was employed to compare the expression profiles of MHCC97L-Control and MHCC97L-shSix1 cells. Twenty-eight downregulated and 24 upregulated genes with known functions were identified in MHCC97L-shSix1. The functions of these target genes are involved in diverse biological activities. Our data suggest that Six1 may be involved in regulation of proliferation and invasiveness of HCC; thus targeting suppression of Six1 is a viable option for treating HCC patients.
我们之前的研究表明，同源盒蛋白 Six1 在肝癌（HCC）患者中的过度表达与静脉浸润、晚期病理肿瘤转移（pTNM 分期）和较差的总生存率有关（Ng 等人，《英国癌症杂志》2006 年；95:1050-5）。在这项研究中，我们使用短发夹 RNA（shRNA）干扰方法抑制转移性 HCC 细胞系 MHCC97L 中的 Six1 表达。建立了携带 Six1 特异性 shRNA 质粒的稳定转染体 MHCC97L-shSix1，与 MHCC97L-Control 相比，下调 Six1 表达约 40%。体外功能测定表明，MHCC97L-shSix1 细胞的生长速度和增殖能力明显下降。此外，MHCC97L-shSix1 细胞的迁移和侵袭能力显著降低。体内异种移植肿瘤发生模型的数据表明，MHCC97L-shSix1 组的肿瘤大小明显减小。实验性和自发性转移模型表明，靶向抑制 Six1 明显减少了 MHCC97L-shSix1 组的肺转移。为了鉴定 Six1 调控的靶标，我们采用 cDNA 微阵列比较了 MHCC97L-Control 和 MHCC97L-shSix1 细胞的表达谱。在 MHCC97L-shSix1 中鉴定出 28 个下调和 24 个上调的具有已知功能的基因。这些靶基因的功能涉及多种生物学活性。我们的数据表明，Six1 可能参与调节 HCC 的增殖和侵袭性；因此，靶向抑制 Six1 可能是治疗 HCC 患者的一种可行方法。
