[Reappraisal of the impacts of human Runt-related transcription factor gene 3 expression on differentiation and prognosis of gastric cancer].

OBJECTIVE: To investigate the expression of Runt-related transcription factor gene 3(RUNX3) in gastric cancer and its impact on the outcome of gastric cancer patients. METHODS: By using immunohistochemistry staining and western blot assay, the expression of RUNX3 protein in 66 cases of gastric cancer with various clinicopathologic characteristics were detected, and the effects of RUNX3 protein expression on the outcome of patients undergone surgical resection were evaluated. RESULTS: (1) The expression rate of RUNX3 protein in gastric cancer lesions was 60.6% (40/66), and RUNX3 protein was mainly expressed in the cytoplasm of cancer cells. RUNX3 protein expression in tumor tissues was significantly higher than that in non-tumor tissues. (2) RUNX3 protein expression was correlated with tumor differentiation (P=0.025) and Lauren's classification (P=0.034), but had no relationship with the TNM stage (P=0.085). (3) In sharp contrast, the median survival time of patients who had tumors with negative and positive RUNX3 protein expression were 2478 and 2187 days respectively (P=0.016). CONCLUSIONS: RUNX3 protein influences the differentiation of gastric cancer. The role of RUNX3 protein as a tumor-suppressor in tumorigenesis and differentiation of gastric carcinoma need to be further evaluated.

Applying proteomic methodologies to analyze the effect of methionine restriction on proliferation of human gastric cancer SGC7901 cells.

BACKGROUND: Methionine dependence is a feature unique to cancer cells, exhibited as inability to grow in a methionine-depleted environment supplemented with homocysteine, the immediate metabolic precursor of methionine. However, the molecular mechanisms by which methionine restriction inhibits cancer cells growth have not been elucidated. The effect of methionine restriction on the protein expression in gastric cancer cells was studied. METHODS: SGC7901 cells were treated with M-H+ medium for 5 days, which was followed by analysis of total cellular protein from cells by a combination of 2-DE and MS. Then the differential expressional levels of partially identified proteins were determined by Western blot analysis. RESULTS: The well-resolved, reproducible 2-DE patterns of SGC7901 cells cultured in M+H- or M-H+ medium were established. The 10 differential proteins between pairs of gastric cancer cells SGC7901 cultured either in M+H- medium or M-H+ medium, were identified by MALDI-TOF/TOF MS, and the differential expression levels of 2 identified proteins were confirmed. CONCLUSION: These data will be valuable for further study of the molecular mechanisms by which methionine restriction induces cell cycle arrest and apoptosis in human gastric cancer.

Methionine-dependence and combination chemotherapy on human gastric cancer cells in vitro.

AIM: To elucidate whether human primary gastric cancer and gastric mucosa epithelial cells in vitro can grow normally in a methionine (Met) depleted environment, i.e. Met-dependence, and whether Met-depleting status can enhance the killing effect of chemotherapy on gastric cancer cells. METHODS: Fresh human gastric cancer and mucosal tissues were managed to form monocellular suspensions, which were then cultured in the Met-free but homocysteine-containing (Met(-)Hcy(+)) medium, with different chemotherapeutic drugs. The proliferation of the cells was examined by cell counter, flow cytometry (FCM) and microcytotoxicity assay (MTT). RESULTS: The growth of human primary gastric cancer cells in Met(-)Hcy(+) was suppressed, manifested by the decrease of total cell counts [1.46 +/- 0.42 (x 10(9).L(-1)) in Met(-)Hcy(+) vs 1.64 +/-0.44(x 10(9).L(-1)) in Met(+)Hcy(-), P<0.01], the decline in the percentage of G(0)G(1) phase cells (0.69 +/- 0.24 in Met(-)Hcy(+) vs 0.80 +/- 0.18 in Met(+)Hcy(-), P<0.01) and the increase of S cells (0.24 +/- 0.20 in Met(-)Hcy(+) vs 0.17 +/- 0.16 in Met(+)Hcy(-), P<0.01); however, gastric mucosal cells grew normally. If Met(-)Hcy(+) medium was used in combination with chemotherapeutic drugs, the number of surviving gastric cancer cells dropped significantly. CONCLUSION: Human primary gastric cancer cells in vitro are Met-dependent; however, gastric mucosal cells have not shown the same characteristics. Met(-)Hcy(+) environment may strengthen the killing effect of chemotherapy on human primary gastric cancer cells.

A study of preoperative methionine-depleting parenteral nutrition plus chemotherapy in gastric cancer patients.

AIM:To investigate the interference of methionine-free parenteral nutrition plus 5-Fu (-MetTPN+5-Fu) in gastric cancer cell kinetics and the side effects of the regimen.METHODS:Fifteen patients with advanced gastric cancer were randomly divided intotwo groups, 7 patients were given preoperatively a seven-day course of standard parenteral nutrition in combination with a five-day course of chemotherapy (sTPN+5-Fu), while the other 8 patients were given methionine-deprived parenteral nutrition and 5-Fu (-MetTPN+5-Fu). Cell cycles of gastric cancer and normal mucosa were studied by flow cytometry (FCM). Blood samples were taken to measure the serum protein, methionine (Met) and cysteine (Cys) levels, and liver and kidney functions.RESULTS:As compared with the results obtained before the treatment, the percentage of G(0)/G(1) tumor cells increased and that of S phase decreased in the -MetTPN+5-Fu group, while the contrary was observed in the sTPN+5-Fu group. Except that the ALT, AST and AKP levels were slightly increased in a few cases receiving -MetTPN+5-Fu, all the other biochemical parameters were within normal limits. Serum Cys level decreased slightly after the treatment in both groups. Serum Met level of patients receiving sTPN+5-Fu was somewhat higher after treatment than that before treatment; however, no significant change occurred in the -MetTPN+5-Fu group, nor operative complications in both groups.CONCLUSION:-MetTPN+5-Fu exerted a suppressive effect on cancer cell proliferation, probably through a double mechanism of creating a state of "Met starvation" adverse to the tumor cell cycle, and by allowing 5-Fu to kill specifically cells in S phase. Preoperative shortterm administration of -MetTPN+5-Fu had little undesirable effect on host metabolism.