Association between expression of activated 72-kilodalton gelatinase and tumor spread in non-small-cell lung carcinoma.

BACKGROUND: Matrix metalloproteinases, in particular the 92-kd and 72-kd gelatinases, have been implicated in the progression of breast, colorectal, and gastric carcinomas, but involvement of the gelatinases in progression of non-small-cell lung carcinoma has not been documented. Immunohistochemical studies have measured the overall expression of these enzymes in tumor tissue but have failed to determine the proportion of active enzyme to latent proenzyme. Because the conversion of the latent proenzyme to active enzyme results in removal of a 10-kd amino-terminal domain, the expression of each proteinase can be determined by zymography, which separates substances according to molecular weight. PURPOSE: The purpose of this study was to examine the expression and activation of 92-kd and 72-kd proenzymes in non-small-cell lung carcinoma. METHODS: Gelatin zymography was used to study the expression of 92-kd and 72-kd gelatinases in 22 samples of non-small-cell lung carcinoma and adjacent uninvolved tissue. Medium conditioned by human RPMI-7951 melanoma cells was used as a marker for the 72-kd proenzyme, and medium conditioned by concanavalin A-treated human HT-1080 fibrosarcoma cells was used as a marker for both the 92-kd proenzyme and the 62-kd activated form of the 72-kd proenzyme. RESULTS: Both 92-kd and 72-kd proenzymes were expressed to varying degrees in the samples studied. The 82-kd activated form of the 92-kd proenzyme was detected in eight tumor samples but in none of the matched uninvolved tissues. Expression of the 62-kd activated form of the 72-kd proenzyme ranged from a strong band in the tumor tissue, with little or none detectable in the adjacent uninvolved tissue, to the presence of only trace amounts of enzyme in both tumor and uninvolved tissue. There was, however, a highly significant statistical association between the level of expression of the 62-kd activated enzyme in the tumor tissue and evidence of tumor spread (P = .001). CONCLUSION: These results demonstrate elevated expression of the activated forms of both the 92-kd and 72-kd proenzymes in non-small-cell lung carcinoma tissue relative to adjacent uninvolved tissue. IMPLICATION: These results indicate that non-small-cell lung carcinoma should be considered as a possible target for metalloproteinase inhibitory therapy.

Expression of activated gelatinase in human invasive breast carcinoma.

The expression of both 92- and 72-kDa gelatinases has been studied in 20 samples of human breast carcinoma by the technique of gelatin zymography. This technique allowed the relative amount of each gelatinase to be determined in small samples of tissue (< 10 mg). More importantly, active and latent forms of the two gelatinases were resolved. Two samples (10-20 mg) were cut from each piece of tumour in order to monitor the variability of gelatinase distribution within that section of tumour. The 72-kDa latent progelatinase was present in 15 of the 20 tumours, with trace amounts in two others. The 62-kDa activated form of this gelatinase was detected in all 15 of the tumours in which the latent form was present. The 92-kDa latent progelatinase was present in 11 of the 20 tumours, with trace amounts in four others. However, the 82-kDa activated form of this gelatinase was only clearly detected in two tumours, although three others showed the presence of trace amounts. The ratio of active to latent forms of the 72-kDa gelatinase ranged from 0.9 to 3.6. There were no marked correlations between gelatinase expression and established staging and prognostic markers. Analysis of three samples of fibroadenoma revealed only very low levels of gelatinase expression. On the basis of these results, activation of the 72-kDa progelatinase appears to be a more common event in invasive breast carcinoma than activation of the 92-kDa progelatinase. However, neither proteinase showed a correlation with metastatic progression, as measured by lymph node involvement.

Two PDGF-B chain residues, arginine 27 and isoleucine 30, mediate receptor binding and activation.

PDGF may be involved in the pathogenesis of a variety of disorders including atherosclerosis and certain types of cancer. There is currently little understanding of the molecular structure of PDGF and of the critical amino acid residues involved in receptor binding and cell activation. Two such PDGF-B chain residues, arginine 27 and isoleucine 30, have been identified by a site-directed mutagenesis programme. Substitutions in these positions can lead to PDGF mutants defective in both receptor affinity and cell activation as judged by displacement of [125I]PDGF-BB, mitogenic assay and inositol lipid turnover. Circular dichroism and fluorescence spectroscopy show that such mutations do not disrupt the structure of PDGF.