Chew E C, Yam H F, Tsao S W, Bernal S D
Department of Anatomy, Chinese University of Hong Kong, Shatin.
Anticancer Res. 1991 May-Jun;11(3):1205-13.
Terminal differentiation is usually achieved in normal as well as transformed squamous epithelial cells when cultured. On the other hand, tumor cells at various differentiation stages and with different biological characteristics comprise the heterogeneous properties of tumors which have been one of the barriers to effective treatments. Recently, a surface membrane protein has been reported in squamous cell carcinomas of the head and neck, which is recognized by a murine monoclonal antibody, SQM1. This glycoprotein was further suggested to be related to squamous cell differentiation and intercellular adhesion. In a recent study, the esophageal carcinoma cells of EC/CUHK2 cell line were induced to various differentiation stages as evidenced by the increasing amount of intracellular desmosomes and tonofilaments and greater binding ratios of cytokeratin and involucrin antibodies than in those cells that maintained lower calcium ion concentrations. The expression of SQM1 antigen was found to increase in intensity when the tumor cells were cultured in moderate to high calcium ion levels for 10 to 15 hours when the differentiation patterns were beginning to appear. The intensity declined gradually thereafter. Thus SQM1 protein might be related to the stage when the cells started committing with squamous differentiation.
终末分化通常在培养的正常及转化鳞状上皮细胞中实现。另一方面，处于不同分化阶段且具有不同生物学特性的肿瘤细胞构成了肿瘤的异质性，这一直是有效治疗的障碍之一。最近，在头颈部鳞状细胞癌中报道了一种表面膜蛋白，它可被鼠单克隆抗体SQM1识别。这种糖蛋白进一步被认为与鳞状细胞分化和细胞间黏附有关。在最近的一项研究中，EC/CUHK2细胞系的食管癌细胞被诱导至不同分化阶段，表现为细胞内桥粒和张力丝数量增加，细胞角蛋白和内聚蛋白抗体的结合率高于维持较低钙离子浓度的细胞。当肿瘤细胞在中高钙离子水平培养10至15小时，分化模式开始出现时，发现SQM1抗原的表达强度增加。此后强度逐渐下降。因此，SQM1蛋白可能与细胞开始进行鳞状分化的阶段有关。
