Llorens A, Vinyals A, Alia P, López-Barcons L, Gonzalez-Garrigues M, Fabra A
Institut de Recerca Oncológica, Cancer & Metastasis Department, Hospital Duran Reynals, L'Hospitalet de Llobregat, Barcelona, Spain.
Mol Carcinog. 1997 May;19(1):54-66. doi: 10.1002/(sici)1098-2744(199705)19:1<54::aid-mc8>3.0.co;2-n.
We have developed a novel murine mammary tumor system with variants representing different stages of tumor progression. The MXT-s parental cell line was established from a urethane-induced and hormone-sensitive mammary tumor. MXT-s parental cells are highly tumorigenic but poorly metastatic. MXT clones and variants were selected by either in vitro or in vivo procedures, and they differ in metastatic ability and 17 beta-estradiol dependency for tumor growth. The MXT-c1.1 and MXT-B2 cell lines produced lung metastasis after intravenous injection into 100% of syngenic mice, but only MXT-c1.1 cells were highly metastatic from intramammary tumors. The fingerprints obtained by arbitrarily primed-polymerase chain reaction demonstrated that the metastatic variants and clones had a common genetic background and resulted from clonal selection from the parental cell line. We studied whether the matrix metalloproteinase (MMP) profile is correlated with tumor progression and metastatic ability in the MXT tumor system. Gelatinases A and B were assayed in the cells, both by enzyme activity and mRNA expression. Gelatinase A was expressed in MXT-c1.1 cells, whereas MXT-B2 cells did not express either MMP. In contrast, the mammary fat pad tumors expressed both gelatinases. Membrane Type 1-MMP transcripts were also detected in MXT cells and tumors. Because the mRNA levels of gelatinase. A were low in MXT-B2 tumors, we suggested that exogenous gelatinase A bound the cell membranes of MXT-B2 cells in vivo. Indirect evidence was obtained in vitro by treatment of MXT-B2 cells with NIH/3T3 fibroblast-conditioned medium. After this treatment, we detected a gelatinolytic activity at M(r) 68,000 in the cell-membrane extract of MXT-B2 cells and an increase in migratory ability through type IV collagen matrices. On the other hand, Ha-ras gene dosage correlated positively with metastatic ability but not with either gelatinase A or gelatinase B expression. No significant differences were observed in the expression of stromelysin-1 and tissue inhibitors of MMP. Thus, in the MXT tumor system, the expression of gelatinase A or its cell association and Ha-ras gene dosage independently contribute to the metastatic phenotype.
我们开发了一种新型的小鼠乳腺肿瘤系统，其变体代表肿瘤进展的不同阶段。MXT-s亲本细胞系是从氨基甲酸乙酯诱导的、激素敏感的乳腺肿瘤中建立的。MXT-s亲本细胞具有高度致瘤性，但转移能力较差。通过体外或体内程序选择MXT克隆和变体，它们在转移能力和肿瘤生长对17β-雌二醇的依赖性方面存在差异。将MXT-c1.1和MXT-B2细胞系静脉注射到100%的同基因小鼠中后会产生肺转移，但只有MXT-c1.1细胞从乳腺内肿瘤具有高度转移性。通过任意引物聚合酶链反应获得的指纹图谱表明，转移变体和克隆具有共同的遗传背景，并且是从亲本细胞系中通过克隆选择产生的。我们研究了基质金属蛋白酶（MMP）谱是否与MXT肿瘤系统中的肿瘤进展和转移能力相关。通过酶活性和mRNA表达对细胞中的明胶酶A和B进行了检测。明胶酶A在MXT-c1.1细胞中表达，而MXT-B2细胞不表达任何一种MMP。相反，乳腺脂肪垫肿瘤同时表达两种明胶酶。在MXT细胞和肿瘤中也检测到了膜型1-MMP转录本。由于MXT-B2肿瘤中明胶酶A的mRNA水平较低，我们推测外源性明胶酶A在体内与MXT-B2细胞的细胞膜结合。通过用NIH/3T3成纤维细胞条件培养基处理MXT-B2细胞在体外获得了间接证据。经过这种处理后，我们在MXT-B2细胞的细胞膜提取物中检测到了68,000分子量的明胶溶解活性，并观察到其通过IV型胶原基质的迁移能力增强。另一方面，Ha-ras基因剂量与转移能力呈正相关，但与明胶酶A或明胶酶B的表达均无关。在基质溶解素-1和MMP的组织抑制剂的表达方面未观察到显著差异。因此，在MXT肿瘤系统中，明胶酶A的表达或其与细胞的结合以及Ha-ras基因剂量独立地促成了转移表型。
