Integrin αvβ6 and matrix metalloproteinase 9 correlate with survival in gastric cancer

AIM: To investigate the expression of integrin αvβ6 and matrix metalloproteinase 9(MMP-9), their association with prognostic factors and to assess their predictive role in gastric cancer patients.METHODS: Immunohistochemistry was used to determine the expressions of integrin αvβ6 and MMP-9 in 126 specimens from patients with primary gastric carcinoma. Associations between immunohistochemical staining and various clinic pathologic variables of tissue specimens were evaluated by the χ2 test and Fisher's exact test. Expression correlation of αvβ6 and MMP-9 was assessed using bivariate correlation analysis. The patients were followed-up every 3 mo in the first two years and at least every 6 mo afterwards, with a median follow-up of 56 mo(ranging from 2 mo to 94 mo).Four different combinations of αvβ6 and MMP-9 levels(that is, both markers positive, both markers negative, αvβ6 positive with MMP-9 negative, and αvβ6 negative with MMP-9 positive) were evaluated for their relative effect on survival. The difference in survival curves was evaluated with a log-rank test. Survival analysis was conducted using the Kaplan-Meier survival and Cox proportional hazards model analysis.RESULTS: The expressions of integrin αvβ6 and MMP-9 were investigated in 126 cases, among which 34.92% were positive for αvβ6 expression, and 42.06% for MMP-9 expression. The expression of αvβ6 was associated with Lauren type, differentiation, N stage, and TNM stage(the P values were 0.006, 0.038, 0.016, and 0.002, respectively). While MMP-9 expression was associated with differentiation, T stage, N stage, and TNM stage(the P values were 0.039, 0.014, 0.033, and 0.008, respectively). The positive correlation between αvβ6 and MMP-9 in gastric cancer was confirmed by a correlation analysis. The Kaplan-Meier survival analysis showed that patients with expression of αvβ6 or MMP-9 alone died earlier than those with negative expression and that patients who were both αvβ6 and MMP-9 positive had a shorter overall survival than those with the opposite pattern(both αvβ6 and MMP-9 negative)(P = 0.000). A Cox model indicated that positive expression of αvβ6 and MMP-9, diffuse Lauren type, as well as a senior grade of N stage, M stage, and TNM stage were predictors of a poor prognosis in univariate analysis. Only αvβ6 and MMP-9 retained their significance when adjustments were made for other known prognostic factors in multivariate analysis(RR = 2.632, P = 0.003 and RR = 1.813, P = 0.007).CONCLUSION: The expression of αvβ6 and MMP-9 are closely correlated, and the combinational pattern of αvβ6 and MMP-9 can serve as a more effective prognostic index for gastric cancer patients.

Safety validation of decision trees for hepatocellular carcinoma

AIM: To evaluate a different decision tree for safe liver resection and verify its efficiency.METHODS: A total of 2457 patients underwent hepatic resection between January 2004 and December 2010 at the Chinese PLA General Hospital,and 634 hepatocellular carcinoma(HCC) patients were eligible for the final analyses. Post-hepatectomy liver failure(PHLF) was identified by the association of prothrombin time < 50% and serum bilirubin > 50 μmol/L(the "50-50" criteria),which were assessed at day 5 postoperatively or later. The Swiss-Clavien decision tree,Tokyo University-Makuuchi decision tree,and Chinese consensus decision tree were adopted to divide patients into two groups based on those decision trees in sequence,and the PHLF rates were recorded.RESULTS: The overall mortality and PHLF rate were 0.16% and 3.0%. A total of 19 patients experienced PHLF. The numbers of patients to whom the SwissClavien,Tokyo University-Makuuchi,and Chinese consensus decision trees were applied were 581,573,and 622,and the PHLF rates were 2.75%,2.62%,and 2.73%,respectively. Significantly more cases satisfied the Chinese consensus decision tree than the Swiss-Clavien decision tree and Tokyo University-Makuuchi decision tree(P < 0.01,P < 0.01); nevertheless,the latter two shared no difference(P = 0.147). The PHLF rate exhibited no significant difference with respect to the three decision trees.CONCLUSION: The Chinese consensus decision tree expands the indications for hepatic resection for HCC patients and does not increase the PHLF rate compared to the Swiss-Clavien and Tokyo UniversityMakuuchi decision trees. It would be a safe and effective algorithm for hepatectomy in patients with hepatocellular carcinoma.

Integrin αvβ6 sustains and promotes tumor invasive growth in colon cancer progression

AIM: To detect the mechanism by which colon tumor escapes the growth constraints imposed on normal cells by cell crowding and dense pericellular matrices.METHODS: An immunohistochemical study of integrin αvβ6 and matrix metalloproteinase-9(MMP-9) was performed on tissue microarrays of 200 spots, including 100 cases of colon tumors. RESULTS: High immunoreactivity for αvβ6(73.7%; 28/38) and MMP-9(76.5%; 52/68) was observed in invasive tumor portions. Furthermore, the effects of integrin αvβ6 on tumor invasive growth in nude mice were detected. Tumor invasive growth and high expression of both αvβ6 and MMP-9 were only seen in tumors resulting from Wi Dr cells expressing αvβ6 in the tumorigenicity assay. Flow cytometry was applied to analyze αvβ6 expression in colon cancer Wi Dr and SW480 cells. The effects of cell density on αvβ6 expression and MMP-9 secretion were also detected by Biotrak MMP-9 activity assay and gelatin zymography assay. High cell density evidently enhanced αvβ6 expression and promoted MMP-9 secretion compared with low density. CONCLUSION: Integrin αvβ6 sustains and promotes tumor invasive growth in tumor progression via a selfperpetuating mechanism. Integrin ανβ6-mediated MMP-9 secretion facilitates pericellular matrix degradation at high cell density, which provides the basis of invasive growth.