Regulation of Wnt signaling pathway by galectin-3 in hepato-biliary-pancreatic cancer : Special reference to mutation of galectin-3

半乳糖凝集素-3(Galectin-3，GAL-3)是一种重要的肿瘤转移调节蛋白，与β-连环蛋白一样，以磷酸化依赖的方式在细胞核和胞浆之间穿梭。我们在此报道，β-连环蛋白对细胞周期蛋白D1和c-myc表达的刺激是GAL-3依赖的。根据TOP/FOPFLASH报告系统，GAL-3与β-连环素/Tcf复合体结合，与核内的β-连环素共定位，诱导Tcf-4的转录活性。我们已经确定了β-连环素GAL-3结合序列，它们分别位于蛋白质的NH2和COOH末端，分别包含氨基酸残基1到131和143到250。对人Gal-3序列的分析表明，Gal-3在结构上与β-catenin相似，因为它还包含糖原合成酶…的共同序列(S92XXXS96)更多)磷酸化，并可作为其底物。此外，Axin是Wnt与β-catenin络合物的调节蛋白，也使用与这里通过缺失突变分析鉴定的相同序列基序与GAL-3结合。这些数据支持Gal-3是Wnt/β-catenin信号通路中的关键调节因子，并强调了Gal-3和β-catenin在功能上的相似性。用聚合酶链式反应-单链构象多态(SSCP)-序列分析方法检测GAL-3基因的表达水平。本研究表明，GAL-3的表达与淋巴结状态、淋巴转移、病理分期和组织学参数有关。GAL-3的表达与Ki-67的表达无相关性。GAL-3表达降低与预后不良显著相关，多因素分析显示GAL-3表达是一个独立的预后因素。在PCR-SSCP序列分析中，GAL-3基因检测到2个单核苷酸多态(SNPs)，但没有发现突变。GAL-3表达降低与胃癌的淋巴转移、分期及分化程度有关。采用免疫组织化学方法检测108例结直肠癌组织中Galectin-3、β-catenin和Ki-67的表达。对Galectin-3在肿瘤表面和侵袭前沿的表达进行了分类，并从统计学角度分析了Galectin-3与临床病理因素的关系。当Galectin-3在肿瘤侵袭前沿的表达低于其表面时，有显著的肝转移(p=0.04)。肿瘤表面β-连环蛋白的表达与肝转移和肿瘤分期显著相关(p=0.03，p=0.04)。提示Galectin-3在结直肠癌的侵袭、转移和增殖过程中表达降低。较少

Galectin-3 (gal-3), a pleiotrophic protein, is an important regulator of tumor metastasis, which like beta-catenin shuttles between the nucleus and the cytosol in a phosphorylation-dependent manner. We report herein that beta-catenin stimulation of cyclin D1 and c-myc expression is gal-3 dependent. Gal-3 binds to beta-catenin/Tcf complex, colocalizes with beta-catenin in the nucleus, and induces the transcriptional activity of Tcf-4 as determined by the TOP/FOPFLASH reporter system. We have identified the beta-catenin gal-3-binding sequences, which are in the NH2 and COOH termini of the proteins encompassing amino acid residues 1 to 131 and 143 to 250, respectively. These data indicate that gal-3 is a novel binding partner for beta-catenin involved in the regulation of Wnt/beta-catenin signaling pathway.Analysis of the human gal-3 sequence reveled a structural similarity to beta-catenin as it also contains the consensus sequence (S92XXXS96) for glycogen synthase kinase-3beta (GSK-3beta … More ) phosphorylation and can serve as its substrate. In addition, Axin, a regulator protein of Wnt that complexes with beta-catenin, also binds gal-3 using the same sequence motif identified here by a deletion mutant analysis. The data presented here give credence to the suggestion that gal-3 is a key regulator in the Wnt/beta-catenin signaling pathway and highlight the functional similarities between gal-3 and beta-catenin.Gal-3 and Ki-67 expressions were assessed by immunohistochemistry in 115 patients with gastric cancer. PCR-single strand conformation polymorphism (SSCP)-sequence analysis and the levels of gal-3 mRNA were also examined. The present study demonstrated that gal-3 expression was correlated with nodal status, lymphatic inivasion, pathological stage and histological parameters. On the other hand, gal-3 expression did not correlate with the expression of Ki-67. Reduced expression of gal-3 was significantly associated with a poor prognosis and multivariate analysis showed that gal-3 expression was an independent prognostic factor. On PCR-SSCP-sequence analysis, 2 single nucleotide polymorphisms (SNPs) were detected in the gal-3 gene, but none showed mutations. Reduced gal-3 expression was associated with lymph node metastasis, advanced stage and tumor differentiation in gastric cancer. Gal-3 expression could be a useful prognostic factor in gastric cancer.Immunohistochemical assessment of galectin-3, beta-catenin and Ki-67 expression was performed on samples from 108 patients with colorectal cancer. The expression of galectin-3 was classified at the tumor surface and the invasive front, and its relationship with clinicopathological factors was considered from a statistical viewpoint. There was significant liver metastasis when the expression of galectin-3 was lower at the invasive front of a tumor compared to its surface (p = 0.04). There were also significant correlations between beta-catenin expression at the tumor surface and liver metastasis and tumor stage (p=0.03, p=0.04 respectively). The reduction of galectin-3 expression in tumor invasion, metastasis and proliferation in patients with colorectal cancer is suggested. Less