Chloride channel calcium-activated (CLCA) genes encode regulators for chloride transport across the cell membrane. As for cancer development, some CLCA genes are considered putative tumor suppressor genes. The aim of this study was to explore whether CLCA4 gene would have mutations in its nucleotide repeats in colorectal cancer (CRC). In a public database, we found that CLCA4 gene had mononucleotide repeats in the coding sequences that might be mutational targets in the cancers with microsatellite instability. For this, the current study studied 146 CRCs for mutation and expression analyses by single-strand conformation polymorphism analysis, DNA sequencing, and immunohistochemistry. Overall, we found CLCA4 frameshift mutations in 12/101 (11.8%) CRCs with high-microsatellite instability (MSI-H), but none in microsatellite stable CRCs (0/45) (P<0.01). In addition, we analyzed intratumoral heterogeneity of the CLCA4 frameshift mutations and found that 1 CRC harbored regional intratumoral heterogeneity of the CLCA4 frameshift mutation. Loss of CLCA4 protein expression was identified in 50% of CRCs. Also, cancers with MSI-H harboring CLCA4 frameshift mutations showed lower CLCA4 immunostaining than those with the wild-type. Our data indicate that the CLCA4 gene harbors alterations both in somatic mutation and expression, suggesting their roles in tumorigenesis of CRC with MSI-H.

中文翻译：

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CLCA4基因的移码突变和表达缺失在微卫星不稳定的结直肠癌中很常见

氯离子通道钙激活 (CLCA) 基因编码氯离子跨细胞膜转运的调节因子。至于癌症发展，一些 CLCA 基因被认为是推定的肿瘤抑制基因。本研究的目的是探讨 CLCA4 基因在结直肠癌 (CRC) 中是否会发生核苷酸重复突变。在一个公共数据库中，我们发现 CLCA4 基因在编码序列中具有单核苷酸重复序列，这可能是具有微卫星不稳定性的癌症中的突变靶标。为此，目前的研究通过单链构象多态性分析、DNA 测序和免疫组织化学研究了 146 个 CRC 的突变和表达分析。总体而言，我们在 12/101 (11.8%) 具有高微卫星不稳定性 (MSI-H) 的 CRC 中发现了 CLCA4 移码突变，但在微卫星稳定的 CRC (0/45) 中没有发现 (P< 0.01)。此外，我们分析了 CLCA4 移码突变的肿瘤内异质性，发现 1 例 CRC 具有 CLCA4 移码突变的区域肿瘤内异质性。在 50% 的 CRC 中发现 CLCA4 蛋白表达缺失。此外，具有 CLCA4 移码突变的 MSI-H 癌症显示出比野生型更低的 CLCA4 免疫染色。我们的数据表明 CLCA4 基因在体细胞突变和表达方面都有改变，表明它们在 MSI-H 结直肠癌的肿瘤发生中的作用。具有 CLCA4 移码突变的 MSI-H 癌症显示出比野生型更低的 CLCA4 免疫染色。我们的数据表明 CLCA4 基因在体细胞突变和表达方面都有改变，表明它们在 MSI-H 结直肠癌的肿瘤发生中的作用。具有 CLCA4 移码突变的 MSI-H 癌症显示出比野生型更低的 CLCA4 免疫染色。我们的数据表明 CLCA4 基因在体细胞突变和表达方面都有改变，表明它们在 MSI-H 结直肠癌的肿瘤发生中的作用。