phenylmercuric-acetate and Neoplasm-Metastasis

Walker 256 (W256) cancer cells, developed as ascites in rats, in response to endogenous unidentified stimuli, secrete a gelatinase of apparent molecular mass of 94 kDa, immunologically homologous to the zymogen of matrix metalloproteinase-9 (proMMP-9). After treatment with the activating agent 4-aminophenylmercuric acetate (APMA), affinity-purified W256 gelatinase is converted to a final processed form of 66 kDa in a similar fashion to TIMP-free human proMMP-9. It is demonstrated that although being capable of binding TIMP-1, W256 proMMP-9 is secreted from W256 cells in TIMP-free forms (monomers or oligomers). Moreover, using biochemical and immunological methods, it is established that the W256 cells do not express or secrete TIMP-1 protein, although RT-PCR analysis indicated low-level TIMP-1 mRNA expression. W256 cancer cells displayed high metastatic ability in rats that may be attributed in part to secretion of TIMP-free proMMP-9.

Topics: Animals; Carcinoma 256, Walker; Cell Line, Tumor; Gelatinases; Humans; Matrix Metalloproteinase 9; Neoplasm Metastasis; Phenylmercuric Acetate; Rats; RNA, Messenger; Tissue Inhibitor of Metalloproteinase-1

Orthotopic implantation of human colon carcinoma cells is useful for studying the behavior of metastatic subpopulations. We observed that the parental line and variants of human colon carcinoma KM12 cells were all tumorigenic following implantation into the subcutis or cecal wall of BALB/c nude mice. Their ability to metastasize to distant organ sites varied, however, with the site of growth. Subcutaneous (SC) tumors did not produce visceral metastases, whereas cecal tumors metastasized to the regional mesenteric lymph nodes and to the liver. To examine the influence of organ environment on the extracellular matrix-degrading activity of the tumors, we inoculated human colon carcinoma cells into the subcutis or cecal wall and after 7 weeks isolated and cultured the tumors in serum-free medium. The conditioned media of SC tumors contained very low levels of type IV collagenase (gelatinase) and heparanase (heparan sulfate-specific endo-beta-D-glucuronidase), whereas the media of the cecal wall tumors contained high levels of both. Zymograms of the media revealed that the intracecal human colon carcinomas secreted more than three times the amount of latent and active forms of 92-kd type IV collagenase than did the SC tumors. Moreover, only the conditioned media of intracecal tumors contained latent and active forms of 64-kd type IV collagenase. Histochemical analysis using rabbit antiserum raised against the synthetic peptides of 72-kd procollagenase type IV showed type IV collagenase in the intracecal tumors; human colon carcinoma growing SC, however, were not stained significantly. These results suggest that factors in the organ environment may affect production and secretion of tumor extracellular matrix-degrading enzymes, and these factors may modify the metastatic behavior of human colon carcinoma cells in nude mice.

Topics: Animals; Carcinogenicity Tests; Cell Communication; Colonic Neoplasms; Extracellular Matrix; Gelatinases; Glucuronidase; Glycoside Hydrolases; Humans; Immunohistochemistry; Male; Matrix Metalloproteinase 9; Metalloendopeptidases; Mice; Mice, Inbred BALB C; Microbial Collagenase; Neoplasm Metastasis; Pepsin A; Phenylmercuric Acetate

Type IV collagen-degrading enzyme activity was measured in liver homogenate obtained from 10 patients with hepatocellular carcinomas. Type IV collagen, the enzyme substrate, was extracted from human placenta with pepsin digestion, and labeled with [1-14C] acetic anhydride. The homogenate was preincubated with p-aminophenylmercuric acetate to activate the latent form of the enzyme, and then the enzyme activity was measured at pH 7.5 by adding a substrate mixture. Referring to previous reports, the enzyme measured seemed to be a neutral metalloprotease. The enzyme activity of the homogenate was markedly reduced by omitting the p-aminophenylmercuric acetate pretreatment, indicating that the enzyme was present mainly in the latent form. The activity seemed to be higher in the peripheral portion of hepatocellular carcinoma than in the center. Further the activity was found to be the highest in a hepatocellular carcinoma patient with many metastatic nodules in the lung. The results might suggest that type IV collagen-degrading enzyme participates in tumor invasion and intrahepatic or remote metastasis.

Topics: Aged; Basement Membrane; Carcinoma, Hepatocellular; Collagen; Electrophoresis, Polyacrylamide Gel; Female; Humans; Liver Neoplasms; Male; Microbial Collagenase; Middle Aged; Neoplasm Invasiveness; Neoplasm Metastasis; Phenylmercuric Acetate