Expression of matrix metalloproteinases 2 and 9 in human gastric cancer and superficial gastritis

Abstract

Aim: To assess expression of matrix metalloproteinases 2 (MMP2) and MMP9 in gastric cancer, superficial gastritis and normal mucosa, and to measure metalloproteinase activity.

Methods: MMP2 and MMP9 mRNA expression was determined by quantitative real-time polymerase chain reaction. Normalization was carried out using three different factors. Proteins were analyzed by quantitative gelatin zymography (qGZ).

Results: 18S ribosomal RNA (18SRNA) was very highly expressed, while hypoxanthine ribosyltransferase-1 (HPRT-1) was moderately expressed. MMP2 was highly expressed, while MMP9 was not detected or lowly expressed in normal tissues, moderately or highly expressed in gastritis and highly expressed in cancer. Relative expression of 18SRNA and HPRT-1 showed no significant differences. Significant differences in MMP2 and MMP9 were found between cancer and normal tissue, but not between gastritis and normal tissue. Absolute quantification of MMP9 echoed this pattern, but differential expression of MMP2 proved conflictive. Analysis by qGZ indicated significant differences between cancer and normal tissue in MMP-2, total MMP-9, 250 and 110 kDa bands.

Conclusion: MMP9 expression is enhanced in gastric cancer compared to normal mucosa; interpretation of differential expression of MMP2 is difficult to establish.

Figure 1

Relative mRNA expression of 18S ribosomal RNA (18SRNA), hypoxanthine ribosyltransferase-1 (HPRT-1), matrix metalloproteinases 2 (MMP2) and MMP9 in three different groups of gastric mucosa tissues. Error bars represent the mean ± SD. ^aP < 0.05 vs normal condition.

Figure 2

Validation of quantitative gelatin zymography (qGZ) of human mucosal biopsy homogenates. A: Representative zymogram of tested samples; B: Representative standard curve generated from human recombinant MMP-2 across linear range of 0.039-1.25 ng/mL, used to generate arbitrary units from densitometric data; C: Differential gelatinase activity of each of the six bands activity detected in normal (open circle), gastritis (open square) and gastric cancer (close square). Error bars represent the mean ± SD. ^aP < 0.05 vs normal condition.