Serini G, Trusolino L, Saggiorato E, Cremona O, De Rossi M, Angeli A, Orlandi F, Marchisio P C
Department of Biological and Technological Research, San Raffaele Scientific Institute, Milan, Italy.
J Natl Cancer Inst. 1996 Apr 3;88(7):442-9. doi: 10.1093/jnci/88.7.442.
BACK: The functional organization of polarized epithelia depends mostly on adhesion molecules belonging to the integrin and cadherin families. These molecules either recognize basement membrane components, such as laminins, or form intercellular junctions via homotypic interactions. Such tissue organization is often disrupted upon neoplastic transformation, and the resulting loss of functional polarization and cell cohesion might be a prerequisite for the invasive and metastatic behavior of carcinomas.
We studied modifications on thyroid adhesive mechanisms at various stages of neoplastic progression in terms of adhesion molecule expression, topography, and functional regulation by tyrosine kinases. Starting from this working hypothesis, we sought to identify one or more biological markers that would be suggestive of malignant transformation and poorer prognosis and that could be developed as a reliable indicator(s) in early diagnostic steps.
The study was carried out on both surgical samples and the corresponding fine-needle aspiration biopsy smears (numbers of specimens collected: 19 adenomas, seven follicular carcinomas, 13 papilary carcinomas, and 39 normal tissues). Immunohistochemistry of tissue sections and smears and immuno-precipitation and western blot analysis of protein extracts were done with a battery of monoclonal and polyclonal antibodies. Northern blotting was performed on RNA extracts from frozen tissue samples and use of an integrin subunit beta4 complementary DNA probe.
Our findings can be summarized as follows: 1) In normal thyroid cells, the cooperative role of integrin alpha6beta4 and laminin 5/kalinin in hemidesmosome-mediated adhesion adhesion is missing, and recognition of the basal lamina occurs via integrin alpha3beta1 and laminin 1 and/or 2 (this pattern being maintained in adenomas but altered in carcinomas regardless of their histotype or differentiation grade); 2) only in carcinomas with clinical and/or histologic aggressiveness do neoexpression of integrin subunit beta4 and loss of laminin 2/merosin occur, indicating de novo assembly of integrin alpha6beta4; 3) pericellular redistribution and cytoskeletal disconnection of the E-cadherin-catenin complex occur; and 4) basal E-cadherin tyrosine phosphorylation decreases in carcinomas as compared with that in normal and adenomatous tissue.
The malignant progression of thyroid tumors involves marked rearrangement of cell-basement membrane and cell-cell adhesion molecules and changes in their cytoskeleton linkage. These rearrangements are also easily and reproducibly detected on fine-needle aspiration biopsy smears.
Immunodetection of adhesion molecules in sections and/or fine-needle smears may complement the toolbox of thyroid surgical pathologists; it may expand the possibilities of achieving a correct early diagnosis of thyroid tumors and of gaining some prognostic information on thyroid tumors.
背景：极化上皮细胞的功能组织主要取决于整合素和钙黏蛋白家族的黏附分子。这些分子要么识别基底膜成分，如层粘连蛋白，要么通过同型相互作用形成细胞间连接。这种组织结构在肿瘤转化时常常被破坏，而功能极化和细胞黏附的丧失可能是癌侵袭和转移行为的先决条件。
我们从黏附分子表达、拓扑结构以及酪氨酸激酶的功能调节方面研究了肿瘤进展不同阶段甲状腺黏附机制的改变。基于这一工作假设，我们试图识别一种或多种提示恶性转化和预后较差的生物标志物，并将其开发为早期诊断步骤中的可靠指标。
该研究在手术样本和相应的细针穿刺活检涂片上进行（收集的标本数量：19例腺瘤、7例滤泡癌、13例乳头状癌和39例正常组织）。用一系列单克隆和多克隆抗体对组织切片和涂片进行免疫组织化学，对蛋白质提取物进行免疫沉淀和蛋白质印迹分析。对冷冻组织样本的RNA提取物进行Northern印迹分析，并使用整合素亚基β4互补DNA探针。
我们的研究结果可总结如下：1）在正常甲状腺细胞中，整合素α6β4和层粘连蛋白5/kalinin在半桥粒介导的黏附中的协同作用缺失，基底膜的识别通过整合素α3β1和层粘连蛋白1和/或2进行（这种模式在腺瘤中保持，但在癌中改变，无论其组织学类型或分化程度如何）；2）仅在具有临床和/或组织学侵袭性的癌中，整合素亚基β4新表达且层粘连蛋白2/merosin缺失，表明整合素α6β4从头组装；3）E-钙黏蛋白-连环蛋白复合物发生细胞周围重新分布和细胞骨架解离；4）与正常和腺瘤组织相比，癌中基底E-钙黏蛋白酪氨酸磷酸化降低。
甲状腺肿瘤的恶性进展涉及细胞-基底膜和细胞-细胞黏附分子的显著重排及其细胞骨架连接的变化。这些重排在细针穿刺活检涂片上也易于重复检测到。
在切片和/或细针涂片上对黏附分子进行免疫检测可能会补充甲状腺外科病理学家的工具库；它可能会扩大正确早期诊断甲状腺肿瘤以及获取甲状腺肿瘤一些预后信息的可能性。
