| Primary gastric malignant lymphoma was the second commonest malignant tumor of the stomach except for gastric carcinoma. Many investigators put emphasis on it because of its increasing incidence in /China in recent years.As a novel tumor suppressor gene, PTEN was closely associated with pathogenesis and progression of all kinds of cancers, after p53 was found. Its product was a kind of phospharase which contributed to carcinogenesis because it played an important role in hyperplasia and apoptosis by reestablishment of cell skeleton and cellular signal transmission. Recently, many studies showed there were several putative mechanisms relating to tumor suppression as follows; inhibiting cell invasion and metastasis by dephosphorating FAK; inhibiting cell apoptosis and increasing cell growth by dephosphorating PIP3; restraining cell differentiation by inhibiting MAPK signal pathway.As a proteinase, Caspase family can directly lead to disorganization of apoptotic cells, which therefore plays a central role in network of apoptosis. Karajewaka et al. firstly detected Caspase -3 (CPP32) expression in tissues from many human organs by immunohistochemis-try, and showed its wide expression in cytoplasm from all kinds of tissues , sometimes in cellular nuclear of lymphocyte B and epithelial cell of gastric pit, suggesting that Caspase - 3 was implicated in regulatingdeath and survival of many cells.This study aimed to investigate relationship between experession of PTEN - encoding product, Gaspase -3 and invasion, metastasis end of primary gastric lymphoma, and to explore the role of PTEN and Caspase - 3 in carcinogenesis and progression of primary gastric lymphoma and its related molecular pathological mechanisms.Materials and methodsFifty - six cases of primary gastric malignant lymphoma were collected from No. 1 Affiliated Hospital of China Medical University and Liaoning tumor Hospital between 1990 and 2000, including 28 men and 28 women. Their age ranged from 21 to 76, with the mean of 53. 1. Among them, 29 tumors invaded below subserosa and 32 accompanied lymph node metastasis. The tissues of primary gastric lymphoma, mucosa adjacent to the tumor and metastatic lesions in each case were jGxed in 10% formalin and embedded in paraffin. Serial 4jxm sections were stained by hemotoxylin and erosin and diagnpsed by two experienced pathologists according to standard citeria.In our study, immunohistochemistry was employed with SABC method ( SABC kit from Boster Biotech. ). Rabbit anti - human Caspase - 3 polyclonal antibody ( from DAKO Biotech) were diluted in phosphate - buffered saline at dilution ratio of 1 -.200, whereas rabbit anti - human PTEN polyclonal antibody ( from Maixim Biotech) was applied without dilution. All procedures were implemented according to the product illustration. Positive and negative controls were performed to ensure the results' reliability. The immunostaining of PTEN and Caspase -3 was localized on the cytoplasm. Specific immu-noreactivity degree was graded as follows-. Negative ( - ) , cells with positive were <5% ;weakly positive ( + ) , cells positive levels were 5 ~25% ; and moderately positive ( ++ ) , cells levels were 25% ~ 50% ; and strongly positive ( -H-f ) , cells were > 50% .Results28 cases (50% ) of primary gastric malignant lymphoma expressed less PTEN - encoding product than 96. 4% of non - tumor mucosa(p <0. 05) , suggesting down - regulated expression of PTEN participated in carcinogenesis of primary gastric malignant lymphoma. Furthermore, loss and low expression of PTEN - encoding product was significantly related to invasive depth and lymph node metastasis (p < 0. 05). Tumors that invaded below the subserosa expressed less PTEN - encoding product than those within properia muscularia( p < 0.05 ). PTEN - encoding product was less expressed in cases with lymph node metastasis than those without lymph node metastasis (p <0.05).The positive rate of Caspase - 3 expression in primary gastric malignant lymphoma was 76. 8% (43/56) , significant...
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