Toxicology and Chemotherapy Unit, German Cancer Research Center (DKFZ), Heidelberg, Germany.
J Cell Mol Med. 2012 Feb;16(2):260-72. doi: 10.1111/j.1582-4934.2011.01289.x.
Terminal progression of colorectal cancer (CRC) culminates in liver metastasis. To identify genes that are involved in the metastatic phenotype, cDNA microarrays were used to analyse mRNA expression profiles of colorectal carcinoma (CC)531 rat colon adenocarcinoma cells for changes related to their homing into the liver. Briefly, CC531 cells were intraportally implanted into the liver of Wag-Rij rats and re-isolated after 3, 6, 9, 14 and 21 days. Compared to control CC531 cells, claudin1 and claudin4 were among the ≥8-fold initially down-regulated genes. The co-culture of tumour cells with isolated rat hepatocytes and Kupffer cells did not induce down-regulation of either claudin1 or 4. When the environment effective on circulating tumour cells was simulated by cell culture conditions favouring their adhesion, only claudin4 showed augmented expression. Knockdown of claudin1 and claudin4 mediated by small interfering RNA caused significantly increased migration and decreased clonogenic growth of tumour cells (P < 0.05), but had no effect on their proliferation. These experimental results were paralleled by increased claudin1 and claudin4 expression in human CRC samples in Union for International Cancer Control (UICC) stages I-III, as evaluated by real-time PCR. Increased claudin4 levels were correlated with significantly reduced overall survival (log-rank test, P= 0.018). Further, significantly (P < 0.05) reduced expression of claudin1 and claudin4 was observed in stage IV and liver metastasis by immunohistochemistry. In conclusion, sequential biphasic changes in claudin1 and claudin4 expression occur during the homing of rat CC531 CRC cells to the liver. This modulation is reflected by significant changes in claudin expression in human primary and metastatic CRC.
结直肠癌（CRC）的终末进展导致肝转移。为了鉴定参与转移表型的基因，我们使用 cDNA 微阵列分析了大鼠结肠腺癌（CC）531 细胞的 mRNA 表达谱，以寻找与它们归巢到肝脏相关的变化。简而言之，将 CC531 细胞门静脉内植入 Wag-Rij 大鼠肝脏中，并在 3、6、9、14 和 21 天后重新分离。与对照 CC531 细胞相比，claudin1 和 claudin4 是最初下调 8 倍以上的基因之一。肿瘤细胞与分离的大鼠肝细胞和库普弗细胞共培养并没有诱导 claudin1 或 4 的下调。当通过有利于肿瘤细胞黏附的细胞培养条件模拟对循环肿瘤细胞有效的环境时，只有 claudin4 显示出增强的表达。小干扰 RNA 介导的 claudin1 和 claudin4 敲低导致肿瘤细胞的迁移显著增加和克隆形成生长减少（P <0.05），但对其增殖没有影响。这些实验结果与通过实时 PCR 评估的国际抗癌联盟（UICC）I-III 期人类 CRC 样本中 claudin1 和 claudin4 的表达增加相平行。claudin4 水平的增加与总生存时间显著缩短相关（对数秩检验，P=0.018）。此外，通过免疫组织化学观察到在 IV 期和肝转移中 claudin1 和 claudin4 的表达显著降低（P<0.05）。总之，在大鼠 CC531 CRC 细胞归巢到肝脏的过程中，claudin1 和 claudin4 的表达发生了顺序的两相变化。这种调节在人类原发性和转移性 CRC 中 claudin 表达的显著变化中得到了反映。
