Niedbala M J, Madiyalakan R, Matta K, Crickard K, Sharma M, Bernacki R J
Cancer Res. 1987 Sep 1;47(17):4634-41.
Penetration of the extracellular matrix (ECM) by tumor cells, an event which occurs at various stages of the metastatic process, involves tumor cell glycosidase mediated hydrolysis of proteoglycans (PG). Recently, we observed that human ovarian carcinoma cell lines (HOCC) derived from primary tumors, peritoneal effusions, and distant metastases possess a varying ability to degrade radiolabeled PG of the ECM, while normal cells (human mesothelial cells or ovarian fibroblasts) fail to do so. To determine whether a quantitative relationship exists between glycosidase activity and degradation of ECM, both intracellular and extracellular glycosidase activities were measured for HOCC and normal cell lines. No relationship was found between intracellular glycosidase activities and the ability of cells to degrade ECM. However, a correlation was observed between extracellular or secretory glycosidase activities and HOCC mediated ECM degradation. In particular, a 5-8-fold increase, as compared to normal cells, was observed for HOCC extracellular beta-N-acetylglucosaminidase (EC 3.2.2.30) activity. The accumulation or secretion of this enzyme from HOCC into culture medium was found to be time dependent and not related to intracellular levels. Purified hexosaminidase derived from invasive HOCC was able to hydrolyze [3H]-glucosamine radiolabeled ECM (up to 30% radiolabel) and resulted in the cumulative release of free [3H]-N-acetylglucosamine. This enzyme mediated hydrolysis could be completely prevented with 2-acetamido-2-deoxy-1,5-D-gluconolactone, a competitive inhibitor (Ki 10(-6) M). Finally, HOCC mediated degradation of radiolabeled ECM was discerned to be dependent upon active hexosaminidase action, since tumor cell mediated degradation of ECM could be inhibited by up to 60% in the presence of this synthetic competitive inhibitor. In summary, these studies indicate a strong association between HOCC solubilization of glycoconjugates present in the ECM and extracellular levels of hexosaminidase.
肿瘤细胞穿透细胞外基质（ECM）这一事件发生在转移过程的各个阶段，涉及肿瘤细胞糖苷酶介导的蛋白聚糖（PG）水解。最近，我们观察到源自原发性肿瘤、腹腔积液和远处转移灶的人卵巢癌细胞系（HOCC）降解ECM放射性标记PG的能力各不相同，而正常细胞（人腹膜间皮细胞或卵巢成纤维细胞）则无法做到这一点。为了确定糖苷酶活性与ECM降解之间是否存在定量关系，我们测量了HOCC和正常细胞系的细胞内和细胞外糖苷酶活性。未发现细胞内糖苷酶活性与细胞降解ECM的能力之间存在关联。然而，观察到细胞外或分泌型糖苷酶活性与HOCC介导的ECM降解之间存在相关性。特别是，与正常细胞相比，HOCC细胞外β-N-乙酰氨基葡萄糖苷酶（EC 3.2.2.30）活性增加了5至8倍。发现该酶从HOCC积累或分泌到培养基中具有时间依赖性，且与细胞内水平无关。源自侵袭性HOCC的纯化己糖胺酶能够水解[3H] - 葡萄糖胺放射性标记的ECM（高达30%的放射性标记），并导致游离[3H] - N-乙酰氨基葡萄糖的累积释放。这种酶介导的水解可以被2-乙酰氨基-2-脱氧-1,5-D-葡萄糖酸内酯完全抑制，后者是一种竞争性抑制剂（Ki 10(-6) M）。最后，由于在这种合成竞争性抑制剂存在下，肿瘤细胞介导的ECM降解可被抑制高达60%，因此可识别出HOCC介导的放射性标记ECM降解依赖于活性己糖胺酶的作用。总之，这些研究表明HOCC对ECM中存在的糖缀合物的溶解与细胞外己糖胺酶水平之间存在密切关联。
