Mori M, Staniunas R J, Barnard G F, Jessup J M, Steele G D, Chen L B
Division of Cellular and Molecular Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.
Gastroenterology. 1993 Sep;105(3):820-6. doi: 10.1016/0016-5085(93)90900-w.
Carbonic anhydrase isoenzymes I and II are present in normal colorectal mucosa. This study aimed to determine if carbonic anhydrase is present in colorectal cancer and what is its potential clinical significance.
The messenger RNA (mRNA) and protein expression of carbonic anhydrase isoenzyme I were analyzed in fresh specimens of colorectal adenocarcinoma by Northern and Western blots, respectively. The immunohistochemical expression was subsequently studied in a larger number of formalin-fixed surgical specimens.
All of 30 normal colon samples had a strong RNA hybridization signal. Only 4 of 39 paired colorectal cancer and none of 9 normal liver samples had detectable levels of carbonic anhydrase mRNA. Isoenzyme I protein expression showed similar results. In a separate group of patients, immunohistochemical studies showed that 16 of 96 colorectal tumors had positive staining cells. All positive tumors were well or moderately differentiated carcinomas (P < 0.05). When analyzed retrospectively, immunoreactive cases were more likely to be in a group with a good outcome (P < 0.01) and to lack vascular invasion (P < 0.01) than negative cases.
The majority of colorectal cancers do not express carbonic anhydrase isoenzyme I. The presence of any isoenzyme I-positive immunoreactive cancer cells may be associated with a more favorable outcome in colorectal cancer.
碳酸酐酶同工酶I和II存在于正常结直肠黏膜中。本研究旨在确定碳酸酐酶是否存在于结直肠癌中及其潜在的临床意义。
分别通过Northern印迹法和Western印迹法分析结直肠腺癌新鲜标本中碳酸酐酶同工酶I的信使核糖核酸（mRNA）和蛋白质表达。随后在大量福尔马林固定的手术标本中研究免疫组化表达。
30份正常结肠样本均有强烈的RNA杂交信号。39对结直肠癌样本中只有4份以及9份正常肝脏样本中均未检测到碳酸酐酶mRNA水平。同工酶I蛋白表达显示出类似结果。在另一组患者中，免疫组化研究显示96例结直肠肿瘤中有16例有阳性染色细胞。所有阳性肿瘤均为高分化或中分化癌（P<0.05）。回顾性分析时，免疫反应阳性病例比阴性病例更可能预后良好（P<0.01）且无血管侵犯（P<0.01）。
大多数结直肠癌不表达碳酸酐酶同工酶I。任何同工酶I阳性免疫反应性癌细胞的存在可能与结直肠癌更有利的预后相关。
