Expression of COX-2, iNOS, p53 and Ki-67 in gastric mucosa-associated lymphoid tissue lymphoma.
OBJECTIVE
To assess the expression of cyclooxygenase-2 (COX-2), nitric oxide synthase (iNOS), p53 and Ki-67 in gastric mucosa-associated lymphoid tissue (MALT) lymphoma and clarify the relationship between COX-2 expression and iNOS or p53 expression in these patients.


METHODS
The expressions of COX-2, iNOS, p53 and Ki-67 were detected in 32 gastric MALT lymphoma specimens and 10 adjacent mucosal specimens by immunohistochemical Envision method.


RESULTS
COX-2 and iNOS expressions were significantly higher in gastric MALT lymphoma tissues than those in adjacent normal tissues. The expression of COX-2 was observed in 22 of 32 cases of MALT lymphoma tissues (68.8%). A positive cytoplasmic immunoreactivity for iNOS was detected in 17 of 31 cases (53.1%). COX-2 expression in gastric MALT lymphoma tissues was positively correlated with iNOS expression (r=0.448, P=0.010) and cell proliferative activity analyzed by Ki-67 labeling index (r=0.410, P=0.020). The expression of COX-2 protein did not correlate with age, sex, stage of disease, lymph node metastasis or differentiation. The accumulation of p53 nuclear phosphoprotein was detected in 19(59.4%) of tumors. p53 protein was expressed in 11 of 23 assessed LG tumors and in 8 of 9 assessed HG tumors. The difference of p53 positivity was found statistically significant between LG and HG cases (P=0.0302). The p53 accumulation correlated with advanced clinical stage (stage III+IV vs stage I+II, P=0.017). There was a significant positive correlation between COX-2 expression and p53 accumulation status (r=0.403, P=0.022). The mean PI of Ki-67 in each grade group were 36.0+/-7.73% in HG and 27.4+/-9.21% in LG. High-proliferation rate correlated with HG tumors (r=0.419, P=0.017). The correlation coefficient showed a significant positive correlation between PI and COX-2 expression in MALT lymphoma patients (r=0.410, P=0.020).


CONCLUSIONS
COX-2 expresses in the majority of gastric MALT lymphoma tissues and correlates with cellular proliferation and iNOS expression. COX-2 overexpression is closely associated with p53 accumulation status. iNOS and COX-2 may play a synergistic role in the pathogenesis of gastric MALT lymphoma.
Li
Hong-Ling
HL
Department of Hematology, Xijing Hospital, Fourth Military Medical University, 127 Changle West Road, Xi'an 710032, Shaanxi Province, China. lhl882002@hotmail.com
Sun
Bing-Zhong
BZ
Ma
Fu-Cheng
FC
D014408:Biomarkers, Tumor; D051546:Cyclooxygenase 2; D005753:Gastric Mucosa / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D019394:Ki-67 Antigen / Q000378:metabolism; D008221:Lymphoid Tissue / Q000378:metabolism / Q000473:pathology; D018442:Lymphoma, B-Cell, Marginal Zone / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D014408:Biomarkers, Tumor; D007527:Isoenzymes; D019394:Ki-67 Antigen; D008565:Membrane Proteins; D016159:Tumor Suppressor Protein p53; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases