Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, Zwijnaarde, 9052, Belgium.
BMC Cancer. 2012 Nov 13;12:515. doi: 10.1186/1471-2407-12-515.
mRNA levels of members of the Vascular Endothelial Growth Factor family (VEGF-A, -B, -C, -D, Placental Growth Factor/PlGF) have been investigated as tissue-based markers of colon cancer. These studies, which used specimens obtained by surgical resection or colonoscopic biopsy, yielded contradictory results. We studied the effect of the sampling method on the marker accuracy of VEGF family members.
Comparative RT-qPCR analysis was performed on healthy colon and colon carcinoma samples obtained by biopsy (n = 38) or resection (n = 39) to measure mRNA expression levels of individual VEGF family members. mRNA levels of genes encoding the eicosanoid enzymes cyclooxygenase 2 (COX2) and 5-lipoxygenase (5-LOX) and of genes encoding the hypoxia markers glucose transporter 1 (GLUT-1) and carbonic anhydrase IX (CAIX) were included as markers for cellular stress and hypoxia.
Expression levels of COX2, 5-LOX, GLUT-1 and CAIX revealed the occurrence in healthy colon resection samples of hypoxic cellular stress and a concurrent increment of basal expression levels of VEGF family members. This increment abolished differential expression of VEGF-B and VEGF-C in matched carcinoma resection samples and created a surgery-induced underexpression of VEGF-D. VEGF-A and PlGF showed strong overexpression in carcinoma samples regardless of the sampling method.
Sampling-induced hypoxia in resection samples but not in biopsy samples affects the marker-reliability of VEGF family members. Therefore, biopsy samples provide a more accurate report on VEGF family mRNA levels. Furthermore, this limited expression analysis proposes VEGF-A and PlGF as reliable, sampling procedure insensitive mRNA-markers for molecular diagnosis of colon cancer.
血管内皮生长因子家族（VEGF-A、-B、-C、-D、胎盘生长因子/PlGF）成员的 mRNA 水平已被作为结肠癌的组织标志物进行研究。这些研究使用手术切除或结肠镜活检获得的标本，得出了相互矛盾的结果。我们研究了采样方法对 VEGF 家族成员标志物准确性的影响。
对通过活检（n=38）或切除（n=39）获得的健康结肠和结肠癌样本进行比较 RT-qPCR 分析，以测量单个 VEGF 家族成员的 mRNA 表达水平。编码环氧合酶 2（COX2）和 5-脂氧合酶（5-LOX）的基因以及编码缺氧标志物葡萄糖转运蛋白 1（GLUT-1）和碳酸酐酶 IX（CAIX）的基因的 mRNA 水平被纳入细胞应激和缺氧的标志物。
COX2、5-LOX、GLUT-1 和 CAIX 的表达水平显示，在健康结肠切除样本中存在缺氧细胞应激，并且同时增加了 VEGF 家族成员的基础表达水平。这种增加消除了匹配的癌切除样本中 VEGF-B 和 VEGF-C 的差异表达，并导致 VEGF-D 的手术诱导低表达。VEGF-A 和 PlGF 无论采样方法如何，在癌样本中均表现出强烈的过表达。
切除样本中的采样诱导的缺氧，但不是活检样本中的缺氧，会影响 VEGF 家族成员的标志物可靠性。因此，活检样本提供了 VEGF 家族 mRNA 水平更准确的报告。此外，这种有限的表达分析提出 VEGF-A 和 PlGF 作为可靠的、不受采样程序影响的 mRNA 标志物，用于结肠癌的分子诊断。
