| BACKGROUND & OBJECTIVE: The researches on the signaling-transduction mechanism were first induced into tumor research fields from 1980's. One of the significant results was that most oncogenes and tumor suppressor genes had been demonstrated as the compositions of signaling transduction system in recent year. The signaling transduction system was classified into: (1) cyclic nucleotide signaling transduction pathway;(2) phosphoric Inositol signaling transduction pathway;(3) proteinase kinase / phosphatase signaling transduction pathway;(4) ion channel;(5) ras/ Raf/ MEK/ ERK signaling transduction pathway. Some growth factors and their receptors such as EGF and PDGF function through MAPK in the progress of tumor conversion, growth and malignant development. Caveolin-1, a proteinase, was reported to participate in signal transduction in tumor cells. Its expression was downregulated or even lost in some cancer cells, but no reports concerning the status of Caveolin-1 in gastric cancer cells has been available. Therefore, the influence of altered Caveolin-1 expression in the stepwise gastrocarcinogenesis was investigated by checking the expression pattern of Caveolin-1 in noncancerous gastric mucosa, intestinal epithelium metaplasia, atypical proliferation and gastric cancer.METHODS: Frozen gastric tissue array-based immunohistochemical staining (IHC) was used to examine the pattern of caveolin-1 expression in 103 tissue spots including 56 cases of gastric cancers, 29 noncancerous mucosa, 11 intestinal metaplasia and 7 atypical hyperplasia. The potential correlations of Caveolin-1 expression with the clinical pathologic stage, lymphoid nodule metastasis,Lauren's classification and histological classification were analyzed as well. There were 26 intestinal type samples, 29 diffuse and 1 mixture type samples according to Lauren's classification According to histological classification, there were 5 papillary adenocarcinoma samples; 51adenocarcinoma samples including 5 well differentiated, 10moderately differentiated and 28 npoorly differentiated, and 8signet ring cell carcinoma comprising, respectively. According to clinical staging, early gastric cancer comprised 6 samples, advanced gastric carcinoma 50, no lymph node metastasis 22, and lymph nodes metastasis 34,respectively. Western blotting was adopted to examine the expression of Caveolin-1 in overall 9 samples from the group of stomach cancer, noncancerous mucosa and dysplasia grade. The number of 12 samples from the group of gastric cancer and noncancerous mucosa were used to dectect the expression of Caveolin-1 by RT- PCR. Gastric cancer cell lines, MGC803 and BGC823, were cultured to be served as experimental cells (Cell saturation for test was 80%) for the detection of Caveolin-1 expression by RT- PCR. RESULTS: (1) The IHC experiments showed that cells with yellow staining in their membrane and plasma were positive expression of Caveolin-1. The expression of Caveolin-1 appeared strong positive in noncancerous gastric mucosa group, positive in intestinal metaplasia group, and weakly positive in atypical hyperplasia group, respectively, but negative in most intestinal type of and diffuse type of gastric cancer, and in signet-ring cell cancer as well. The positive rates of caveolin-1 in noncancerous mucosa, intestinal metaplasia, atypical hyperplasia and gastric cancer were 84.8% (25/29), 81.8% (9/11), 57.1% (4/7) and 17.9% (10/56), respectively. The rates of caveolin-1 detection were significantly different i) between cancer groups and their preneoplastic or noncancerous counterparts (P<0.01, P<0.05) and ii) between diffuse type (7%) and intestinal type of gastric cancers (26.9%) (P<0.05). The frequency of caveolin-1 expression in advanced gastric cancers (16%) was much lower than that of early gastric cancer (33.3%). Caveolin-1 expression was decreased distinctively in the cases with lymph node metastases (p<0.05). (2) The results by Western blotting showed that Caveolin-1 expression contained difference in each group, but had no obvious re... |
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