Rochefort H, Capony F, Garcia M, Cavaillès V, Freiss G, Chambon M, Morisset M, Vignon F
Unité d'Endocrinologie Cellulaire et Moléculaire, INSERM, Montpellier, France.
J Cell Biochem. 1987 Sep;35(1):17-29. doi: 10.1002/jcb.240350103.
In an attempt to understand the mechanism by which estrogens stimulate cell proliferation and mammary carcinogenesis, metastatic human breast cancer cell lines (MCF7, ZR75-1) were found to secrete a 52,000 dalton (52K) protein under estrogen stimulation. Following its purification to homogeneity, the 52K protein was identified as a secreted procathepsin-D-like aspartyl protease bearing mannose-6-phosphate signals. This precursor displays an in vitro autocrine mitogenic activity on estrogen-deprived MCF7 cells and is able to degrade basement membrane and proteoglycans following its autoactivation. The total protease (52K + 48K and 34K) was detected and assayed by monoclonal antibodies and was found to be highly concentrated in proliferative and cystic mastopathies. In breast cancer, its cytosolic concentration appears to be correlated more to tumor invasiveness than to hormone responsiveness. The mRNA of the 52K protease accumulates rapidly following estradiol treatment, as was shown by Northern blot analysis with cloned cDNA. The 52K cathepsin-D-like protease is the first example of a lysosomal protease induced by estrogens in cancer cells. Results obtained using different approaches suggest that two cysteinyl cathepsins are also related to cell transformation and invasiveness. It has been proposed that cathepsin-B is involved in breast cancer and metastatic melanoma, and its regulation by estrogen has been shown in the rat uterus. Cathepsin-L corresponds to the major excreted protein (MEP) whose synthesis and secretion are markedly increased by transformation of NIH 3T3 cells with Ki ras and are regulated by several growth factors. In addition to secreted autocrine growth factors and to other proteases (plasminogen activator, collagenase), lysosomal cathepsins may therefore play an important role in the process of tumor growth and invasion as long as their precursor is secreted abundantly.
为了了解雌激素刺激细胞增殖和引发乳腺癌的机制，研究人员发现转移性人乳腺癌细胞系（MCF7、ZR75-1）在雌激素刺激下会分泌一种52,000道尔顿（52K）的蛋白质。在将其纯化至同质后，该52K蛋白质被鉴定为一种带有甘露糖-6-磷酸信号的分泌型组织蛋白酶D样天冬氨酸蛋白酶前体。这种前体在雌激素缺乏的MCF7细胞上表现出体外自分泌促有丝分裂活性，并且在自身激活后能够降解基底膜和蛋白聚糖。通过单克隆抗体检测和测定了总蛋白酶（52K + 48K和34K），发现其在增殖性和囊性乳腺病中高度浓缩。在乳腺癌中，其胞质浓度似乎与肿瘤侵袭性的相关性比与激素反应性的相关性更大。用克隆的cDNA进行Northern印迹分析表明，雌二醇处理后52K蛋白酶的mRNA迅速积累。52K组织蛋白酶D样蛋白酶是癌细胞中由雌激素诱导的溶酶体蛋白酶的首个实例。使用不同方法获得的结果表明，两种半胱氨酸组织蛋白酶也与细胞转化和侵袭有关。有人提出组织蛋白酶B与乳腺癌和转移性黑色素瘤有关，并且已在大鼠子宫中显示其受雌激素调节。组织蛋白酶L对应于主要分泌蛋白（MEP），其合成和分泌在NIH 3T3细胞用Ki ras转化后明显增加，并受多种生长因子调节。因此，除了分泌的自分泌生长因子和其他蛋白酶（纤溶酶原激活剂、胶原酶）外，只要其前体大量分泌，溶酶体组织蛋白酶可能在肿瘤生长和侵袭过程中起重要作用。
