Mastroianni A, Invernizzi L, Tagliabue E, Fassina G, Albini A, Ménard S, Colnaghi M I
Divisione di Oncologia Sperimentale E. Istituto Nazionale Tumori, Milano, Italia.
Tumour Biol. 1993;14(5):279-87. doi: 10.1159/000217840.
Basement membranes are frequently absent in small-cell lung cancer (SCLC). To study this phenomenon, the production of laminin by SCLC cells, both in vitro and in vivo, has been investigated and compared with the laminin production by lung carcinomas of other histotypes (non-SCLC, NSCLC). Immunoradiometric and immunoperoxidase tests, respectively, carried out on culture supernatants and cells using antilaminin rabbit antiserum, revealed that in 1 (H446) out of 8 SCLC cell lines tested and in the NSCLC line Calu3, laminin was detectable both in the culture medium and in the cytoplasm of the cells. After treatment of an SCLC-negative cell line (N592) with monensin, a molecule which inhibits protein secretion, laminin became detectable in the cytoplasm. Similar results were obtained by FACS analysis on cells permeabilized with saponin. Northern analysis indicated that the laminin B1 gene was transcribed. The level of mRNA for the B1 laminin subunit in the N592 cells was twice and 4 times higher than that found in the laminin-secreting Calu3 and H446 cell lines. The production of laminin in SCLC and NSCLC surgically resected samples using immunoperoxidase staining of cryostatic sections was also investigated. The results indicate that 85% of the NSCLC cases tested showed diffuse staining in the cytoplasm of the tumor cells and strong staining at the basement membrane level, whereas a similar staining was only found in 15% of the SCLC cases tested. The treatment of SCLC cells with differentiating agents in vitro has been shown to induce the adhesion of these cells. In fact, n-butyric acid induced the disaggregation of floating-clump cells and single-cell adhesion in the N592 line, whereas after treatment with retinoids the clumps of the N592 cells were still present, but 30% of these were found to adhere to the plate. However, no increase in the laminin production was found in the cytoplasmic or culture medium under these conditions.
基底膜在小细胞肺癌（SCLC）中常常缺失。为研究这一现象，对SCLC细胞在体外和体内层粘连蛋白的产生进行了研究，并与其他组织学类型肺癌（非SCLC，NSCLC）的层粘连蛋白产生情况进行了比较。分别使用抗层粘连蛋白兔抗血清对培养上清液和细胞进行免疫放射分析和免疫过氧化物酶检测，结果显示，在8个检测的SCLC细胞系中的1个（H446）以及NSCLC细胞系Calu3中，在培养基和细胞胞质中均可检测到层粘连蛋白。用莫能菌素（一种抑制蛋白质分泌的分子）处理SCLC阴性细胞系（N592）后，在胞质中可检测到层粘连蛋白。对经皂素通透处理的细胞进行荧光激活细胞分选分析（FACS）也得到了类似结果。Northern分析表明层粘连蛋白B1基因被转录。N592细胞中层粘连蛋白B1亚基的mRNA水平比分泌层粘连蛋白的Calu3和H446细胞系中的水平分别高两倍和四倍。还使用冰冻切片的免疫过氧化物酶染色法研究了手术切除的SCLC和NSCLC样本中层粘连蛋白的产生情况。结果表明，85%的检测NSCLC病例在肿瘤细胞胞质中显示弥漫性染色，在基底膜水平显示强染色，而在仅15%的检测SCLC病例中发现类似染色。体外使用分化剂处理SCLC细胞已显示可诱导这些细胞黏附。事实上，正丁酸诱导N592细胞系中漂浮团块细胞解聚和单细胞黏附，而用类视黄醇处理后，N592细胞的团块仍然存在，但其中30%被发现黏附于平板。然而，在这些条件下，胞质或培养基中层粘连蛋白的产生未发现增加。
