Aim: The expressive balance between matrix metalloproteinase-9 (MMP-9) and its tissue inhibitor of metalloproteinase-1 (TIMP-1) plays a critical role in maintaining the degradation and synthesis of extracellular matrix. Loss of such balance is associated with invasion and metastasis of tumors. This study aimed to determine the expression of MMP-9 and TIMP-1 in gastric carcinoma, and the association of the expressive imbalance between MMP-9 and TIMP-1 with the invasion and metastasis and prognosis of gastric carcinoma.
Methods: We used immunohistochemistry to determine the expressions of MMP-9, TIMP-1 and proliferating cell nuclear antigen Ki-67 in the gastric specimens taken from 256 patients with primary gastric carcinoma. The patients were followed-up for up to 96 months.
Results: No association between the expression of MMP-9 and TIMP-1 and patients' sex and age, tumor size and location of gastric carcinoma was observed. The incidence of the positive expression of MMP-9 in cases with tumors invasion to muscularis propria and visceral peritoneum (70.13 % and 69.09 %, respectively) was significantly higher than that in cases with tumor invasion only to lamina propria or submucosa (42.50 %, P=0.0162). The positive correlation between MMP-9 expression and the depth of tumor invasion was observed (Pearson correlation coefficient=0.2129, P=0.016). Along with the increase of the metastatic station of lymph nodes, the incidence of the MMP-9 expression was increased by degrees; a positive correlation between them was observed (Pearson correlation coefficient=0.2910, P=0.0001). There was also a significant correlation between MMP-9 expression and the TNM stage in gastric carcinoma (Pearson correlation coefficient=0.3027, P<0.0001). The incidence of MMP-9 expression in stage II and III/IV (75.00 % and 76.15 %, respectively) was significantly higher than those in stage I (46.15 %, P<0.0001). A negative correlation between TIMP-1 immunoreactivity and the depth of invasion, status of lymph node metastasis and TNM stage was observed (Pearson correlation coefficient =-0.1688, -0.3556 and -0.3004, P=0.023, <0.0001 and <0.0001, respectively). Four types of co-expression of MMP-9 and TIMP-1 were observed; i.e. MMP-9 positive but TIMP-1 negative (n=115), both positive (n=52), both negative (n=62) and MMP-9 negative but TIMP-1 positive (n=27). The frequency of serosal invasiveness was significant higher in patients with MMP-9 but without TIMP-1 expression than those with other types of the co-expression (P=0.0303). The incidence of lymph node metastasis was highest in patients with MMP-9 but without TIMP-1 expression, and lowest in those with TIMP-1 but without MMP-9 expression (P<0.0001). The survival rate in patients with MMP-9 but without TIMP-1 expression was lower than that in those with TIMP-1 but without MMP-9 expression (P=0.0014).
Conclusion: Our results in gastric carcinoma demonstrated a significant positive association of MMP-9 over-expression with proliferation of tumor cells, the depth of invasiveness, lymph node metastasis and TNM stage, suggesting MMP-9 can serve as a molecular marker of tumor invasion and metastasis. We also demonstrate a significant negative relationship of TIMP-1 expression with the depth of invasiveness and lymph node metastasis, which provide a new idea in the tumor biological and genetic treatment. The interaction between MMP-9 and TIMP-1 in the processes of tumor invasion and metastasis is that MMP-9 mainly promotes tumor invasion and metastasis and TIMP-1 inhibits functions of MMP-9. The imbalance between MMP-9 and TIMP-1 expression may suggest the occurrence of tumor invasion and metastasis, predict poor prognosis. For patients with imbalanced MMP-9 and TIMP-1 expression, the optimal treatment scheme needs to be selected.