Schneider F, Kemmner W, Haensch W, Franke G, Gretschel S, Karsten U, Schlag P M
Robert-Rössle-Klinik at the Max Delbrück Center for Molecular Medicine, Department for Surgery and Surgical Oncology, Lindenberger Weg 80, D-13122 Berlin, Germany.
Cancer Res. 2001 Jun 1;61(11):4605-11.
Thomsen-Friedenreich (TF)-related blood group antigens, such as TF, Tn, and their sialylated variants, belong to a family of tumor-associated carbohydrates. The aim of the present study was to examine tumor-associated alterations of glycosyltransferases involved in the biosynthesis of the TF glycotope in colorectal carcinomas. To this end, glycosyltransferase expression was examined in 40 cases of colorectal carcinoma specimens classified according to the WHO/Union International Contre Cancer guidelines and in "normal" mucosa of the same patients. Occurrence of TF glycotope was examined by immunohistochemistry with the monoclonal antibody A78-G/A7. Expression of sialyltransferases CMP-sialic acid:Galbeta1,3GalNAc-R alpha3-sialyltransferase I and II (ST3Gal-I and ST3Gal-II) and CMP-sialic acid:Galbeta1,3GalNAc-R alpha6-sialyltransferase (ST6GalNAc-II) and of core 2 beta1,6-N-acetylglucosaminyltransferase was determined by reverse transcription-PCR in the same cryostat sections used for immunohistochemistry. Additionally, alpha2,3-sialyltransferase enzyme activity was studied in each of these tissues. The TF glycotope was detected in 7% of the normal mucosa, but in 57% of the carcinoma samples. Expression of alpha2,3-sialyltransferases ST3Gal-I, ST3Gal-II, and enzyme activity of alpha2,3-sialyltransferase was significantly increased (P < 0.001) in carcinoma specimens compared with normal mucosa. ST3Gal-I mRNA expression was significantly increased (P = 0.05) in cases showing invasion of lymph vessels. Expression of ST6GalNAc-II was significantly increased (P = 0.04) in cases with metastases to lymph nodes along the vascular trunk. Moreover, ST6GalNAc-II expression provides an prognostic factor for patient survival (log rank, P = 0.02). In an attempt to study the functional relevance of the glycosyltransferases for TF biosynthesis, SW480 colorectal cells were transfected with each of the enzymes, and cell surface expression of the TF glycotope was examined by flow cytometry. The presence of TF was not altered by transfection of the cells with either sialyltransferase ST3Gal-I or ST3Gal-II. However, successful transfection with core 2 beta1,6-N-acetylglucosaminyltransferase led to reduced expression of TF. In contrast, increased cell surface expression of TF was found after ST6GalNAc-II transfection. Thus, expression of TF on the cell surface of SW480 colorectal carcinoma cells depends on the ratio of core 2 beta1,6-N-acetylglucosaminyltransferase and ST6GalNAc-II. Earlier immunohistological studies demonstrated that TF is a prognostic factor for patient survival. Our results suggest that sialyltransferase ST6GalNAc-II is of crucial relevance for the prognostic significance of TF.
与汤姆森 - 弗里德赖希（TF）相关的血型抗原，如TF、Tn及其唾液酸化变体，属于肿瘤相关碳水化合物家族。本研究的目的是检测参与结直肠癌中TF糖表位生物合成的糖基转移酶的肿瘤相关改变。为此，根据世界卫生组织/国际癌症研究机构指南对40例结直肠癌标本以及同一患者的“正常”黏膜中的糖基转移酶表达进行了检测。通过使用单克隆抗体A78 - G/A7的免疫组织化学方法检测TF糖表位的出现情况。通过逆转录 - PCR在用于免疫组织化学的相同低温切片中测定唾液酸转移酶CMP - 唾液酸：Galβ1,3GalNAc - Rα3 - 唾液酸转移酶I和II（ST3Gal - I和ST3Gal - II）、CMP - 唾液酸：Galβ1,3GalNAc - Rα6 - 唾液酸转移酶（ST6GalNAc - II）以及核心2β1,6 - N - 乙酰葡糖胺基转移酶的表达。此外，还研究了这些组织中每一个的α2,3 - 唾液酸转移酶活性。在7%的正常黏膜中检测到TF糖表位，但在57%的癌样本中检测到。与正常黏膜相比，癌标本中α2,3 - 唾液酸转移酶ST3Gal - I、ST3Gal - II的表达以及α2,3 - 唾液酸转移酶活性显著增加（P < 0.001）。在显示淋巴管侵犯的病例中，ST3Gal - I mRNA表达显著增加（P = 0.05）。在沿血管主干有淋巴结转移的病例中，ST6GalNAc - II的表达显著增加（P = 0.04）。此外，ST6GalNAc - II表达为患者生存提供了一个预后因素（对数秩检验，P = 0.02）。为了研究糖基转移酶对TF生物合成的功能相关性，用每种酶转染SW480结肠癌细胞，并通过流式细胞术检测TF糖表位的细胞表面表达。用唾液酸转移酶ST3Gal - I或ST3Gal - II转染细胞后，TF的存在没有改变。然而，用核心2β1,6 - N - 乙酰葡糖胺基转移酶成功转染导致TF表达降低。相反，在ST6GalNAc - II转染后发现TF的细胞表面表达增加。因此，SW480结肠癌细胞表面TF的表达取决于核心2β1,6 - N - 乙酰葡糖胺基转移酶和ST6GalNAc - II的比例。早期的免疫组织学研究表明TF是患者生存的一个预后因素。我们的结果表明唾液酸转移酶ST6GalNAc - II对于TF的预后意义至关重要。
