Castronovo V, Campo E, van den Brûle F A, Claysmith A P, Cioce V, Liu F T, Fernandez P L, Sobel M E
Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
J Natl Cancer Inst. 1992 Aug 5;84(15):1161-9. doi: 10.1093/jnci/84.15.1161.
Interactions between cells and the basement membrane glycoprotein laminin are altered during colon cancer progression. Colon carcinoma and normal mucosa cells express a variety of laminin-binding proteins, including the 67-kd laminin receptor (67 LR) and a 31-kd human laminin-binding protein (HLBP31) homologous to the 31-kd human IgE-binding protein/galactoside-binding lectin.
To investigate whether various laminin-binding proteins are differentially expressed in human colon carcinoma, we studied messenger RNA (mRNA) levels of the 67 LR and HLBP31 in matched tumor and adjacent normal mucosa samples from a series of 21 patients.
Total cellular RNA from tumor and normal mucosa was isolated and analyzed by Northern and slot blot hybridization. In addition, HLBP31 protein levels were assessed by the immunoblot technique. Quantitative laminin affinity chromatography was also used to measure the synthesis of HLBP31 protein in five human cancer cell lines.
The steady-state mRNA level of HLBP31 was downregulated (i.e., decreased) in 18 of 21 human colon carcinomas compared with the level in their corresponding normal colonic mucosa. On average, the level of HLBP31 mRNA was decreased 50% +/- 30% (+/- SD) in the colon cancers. The mean ratio of colon cancer HLBP31 mRNA to adjacent normal mucosa HLBP31 mRNA was twofold lower in primary tumors of patients with metastases (0.3 +/- 0.2 SD) than in primary tumors of patients free of metastatic lesions (0.6 +/- 0.2 SD). The differences between the two groups of patients were statistically significant (P less than .05, Wilcoxon-Mann-Whitney test). We have previously shown that the ratio of colon cancer 67 LR mRNA to corresponding normal mucosa 67 LR mRNA was increased in the same patient population. When the two ratios (ratio of cancer to normal HLBP31 mRNA and ratio of cancer to normal 67 LR mRNA) were compared, HLBP31 mRNA/67 LR mRNA was significantly lower (P less than .05) in primary tumors with metastases (mean +/- SD, 0.3 +/- 0.2) than in primary cancers without metastases (mean +/- SD, 0.7 +/- 0.5). The steady-state level of HLBP31 mRNA was directly correlated with the amount of HLBP31 protein in both colon tissue samples and human cancer cell lines.
HLBP31 mRNA expression in colon cancer tissues is modulated inversely to that of 67 LR mRNA expression. The down-regulation of HLBP31 appears to be associated with the metastatic capabilities of colon cancer cells.
Prospective studies on a large cohort should determine if the systematic detection of HLBP31 and 67 LR protein and/or mRNA can be a valuable adjunct in the prognostic evaluation of primary colon cancers.
在结肠癌进展过程中，细胞与基底膜糖蛋白层粘连蛋白之间的相互作用会发生改变。结肠癌和正常黏膜细胞表达多种层粘连蛋白结合蛋白，包括67-kd层粘连蛋白受体（67 LR）和一种与31-kd人IgE结合蛋白/半乳糖苷结合凝集素同源的31-kd人层粘连蛋白结合蛋白（HLBP31）。
为了研究各种层粘连蛋白结合蛋白在人结肠癌中是否存在差异表达，我们研究了21例患者配对的肿瘤及相邻正常黏膜样本中67 LR和HLBP31的信使核糖核酸（mRNA）水平。
从肿瘤和正常黏膜中分离总细胞RNA，并通过Northern杂交和狭缝印迹杂交进行分析。此外，通过免疫印迹技术评估HLBP31蛋白水平。还使用定量层粘连蛋白亲和色谱法测量5种人癌细胞系中HLBP31蛋白的合成。
与相应正常结肠黏膜相比，21例人结肠癌中有18例HLBP31的稳态mRNA水平下调（即降低）。平均而言，结肠癌中HLBP31 mRNA水平降低了50%±30%（±标准差）。有转移患者的原发性肿瘤中结肠癌HLBP31 mRNA与相邻正常黏膜HLBP31 mRNA的平均比值（0.3±0.2标准差）比无转移病变患者的原发性肿瘤（0.6±0.2标准差）低两倍。两组患者之间的差异具有统计学意义（P<0.05，Wilcoxon-Mann-Whitney检验）。我们之前已表明，在同一患者群体中，结肠癌67 LR mRNA与相应正常黏膜67 LR mRNA的比值增加。当比较这两个比值（癌与正常HLBP31 mRNA的比值和癌与正常67 LR mRNA的比值）时，有转移的原发性肿瘤（平均值±标准差，0.3±0.2）中HLBP31 mRNA/67 LR mRNA显著低于无转移的原发性癌（平均值±标准差，0.7±0.5）（P<0.05）。在结肠组织样本和人癌细胞系中，HLBP31 mRNA的稳态水平与HLBP31蛋白的量直接相关。
结肠癌组织中HLBP31 mRNA的表达与67 LR mRNA的表达呈反向调节。HLBP31的下调似乎与结肠癌细胞的转移能力有关。
对大量队列的前瞻性研究应确定HLBP31和67 LR蛋白及/或mRNA的系统检测是否可作为原发性结肠癌预后评估的有价值辅助手段。
