The relationship between apoptosis and the expression of proliferating cell nuclear antigen and the clinical stages in gastric carcinoma

Expression of nitric oxide synthase in human gastric carcinoma and its relation to p53, PCNA

AIM: To investigate the expression of NOS in gastric carcinoma, and to explore the relationship between the expression of nitric oxide synthases (NOS) and p53, PCNA, pathological features and clinical staging of gastric cancer.

METHODS: The activity of NOS protein was investigated in 85 samples of human gastric carcinoma and 25 samples of normal gastric mucosal tissue by biochemical assay. We then examined the expression of NOS, p53, PCNA in 85 samples of human gastric cancer was examined by immunohistochemistry, and NOS mRNA expression in 85 gastric cancer tissue specimens by in situ hybridization.

RESULTS: Biochemical assay showed that the activity of NOS was significantly higher in gastric carcinoma than in normal gastric mucosal tissues (t = 0.4161, P<0.01). Immunohistochemistry revealed that endothelial nitric oxide synthase (eNOS) expressed in all samples of normal gastric mucosa, but only 6 cases of 85 gastric cancer specimens showed weak positive immunohistochemical reactions to eNOS (20%). Inducible nitric oxide synthase (iNOS) was expressed strongly in human gastric carcinoma (81.2%). In situ hybridization analysis showed that iNOS mRNA expression was significantly stronger than eNOS mRNA expression in gastric cancer tissue (χ² = 10.23, P<0.01). The expression of iNOS in gastric cancer was associated with differentiation, clinical stages or lymph node metastases (r = 0.3426, P<0.05). However, iNOS expression did not correlate with histological classifications and morphological types. The expression of iNOS was significantly correlated with p53 or PCNA expression (r = 0.3612, P<0.05). The expression of neuronal nitric oxide synthase (nNOS) was not examined by immunohistochemistry and in situ hybridization in gastric cancer specimens and normal gastric mucosa.

CONCLUSION: In human gastric cancer, there is an enhanced expression of iNOS, but not of eNOS. NOS promotes the proliferation of tumor cells and plays an important role in gastric cancer spread. Inactivation of antioncogene p53 and overexpression of iNOS might play a synergetic role in the process of carcinogenesis of human gastric carcinoma.

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Mast cell density and the context of clinicopathological parameters and expression of p185, estrogen receptor, and proliferating cell nuclear antigen in gastric carcinoma

AIM: To investigate the relationship between the mast cell density (MCD) and the context of clinicopathological parameters and expression of p185, estrogen receptor (ER), and proliferating cell nuclear antigen (PCNA) in gastric carcinoma.

METHODS: Mast cell, p185, ER, and PCNA were detected using immunohistochemical S-P labeling method. Mast cell was counted in tissue of gastric carcinoma and regional lymph nodes respectively, and involved lymph nodes (ILN) were examined as usual.

RESULTS: MCD was significantly related to both age and depth of penetration (χ² = 4.688,P < 0.05 for age and χ² = 9.350, P < 0.01 for depth of penetration) between MCD > 21/0.03 mm² and MCD ≤ 21/0.03 mm² in 100 patients; MCD in 1-6 ILN group patients was significantly higher than that in 7-15 ILN or > 15 ILN group patients (u = 6.881, 8.055, P < 0.01); There were significant differences intergroup in positive expression rate of p185, ER and PCNA between MCD > 21/ 0.03 mm² and MCD ≤ 21/0.03 mm² in 100 patients.

CONCLUSION: Mast cell may have effect on inhibiting invasive growth of tumor, especially in the aged patients; The number of mast cells, in certain degree, may predicate the number of involved lymph nodes, which is valuable for assessment of prognosis; MCD was related to the expression of p185, ER, and PCNA in gastric carcinoma. It suggests that mast cell accumulation may inhibit the proliferation and the dissemination of the gastric carcinoma.