| Adenoid cystic carcinoma is one of the most common malignant salivary gland tumors. This cancer, which is biologically aggressive, is characterized by high incidence of recurrence and distant metastasis after excision of the primary tumor. ECM (extracellular matrix) is complicated reticular structure, which is composed of fibrous protein and proteoglucan. It is essential in many physiological processes, e.g., during development, growth, and repair of tissues. Degradation of ECM around tumor is one of the essential steps in the process of tumor invasion and metastasis. MMPs are a family of at least 18 zinc-dependent endopeptidases, capable of degrading essentially all ECM components. MMP-2 is one of the proteases. Studies show that MMPs not only facilitate invasion by degradation of ECM, but also play an important role in tumor growth and angiogenesis. Expression of MMPs is strongly linked with poor prognosis of malignant tumor. Anti-cancer therapy aiming directly at MMPs receives attention increasingly. Doxycycline, a kind of antibiotic belonging to tetracyclines, can inhibit activity of MMPs and decrease incidence of invasion as well as metastasis of tumor. To demonstrate the role of MMP-2 in invasion of adenoid cystic carcinoma and to clarify the effect of doxycycline on proliferation, activity of MMP-2 and invasive behavior of adenoid cystic carcinoma cell, we carried out some experiments as fellow and the results are listed below:1. Expression of MMP-2 in adenoid cystic carcinoma and pleomorphic adenomaExpression of MMP-2 in adenoid cystic carcinoma and pleomorphic adenoma was examined by immunohistochemical staining. Deference of expression of MMP-2 was significant (P<0.05), which was 28.6% and 82.6% respectively in pleomorphic adenoma and adenoid cystic carcinoma. Expression of MMP-2 in normal salivary gland was negative.Expression of MMP-2 in the solid type was stronger than that in the tubular type, the difference between which was significant (P<0.01). Deference of expression of MMP-2 between the cribriform type and the solid type as well as the tubular type was not significant.2. Factors correlated to prognosis of adenoid cystic carcinoma Expression of MMP-2. VEGF and TNF a was examined by immunohistochemical technique and the results were correlated with clinicopathological tumor parameters. Expression of MMP-2 in patients developing local recurrence was higher than those without recurrence (PO.05). Spearman correlation analysis revealed that expression of MMP-2 correlated with local recurrence closely (r=0.445,P<0.05). There was significant difference in the expression of MMP-2 between the death group and survival group. Expression of VEGF in the death group increased greatly (P<0.01). Spearman correlation analysis revealed that expression of VEGF correlated with local recurrence closely (r=0.445,P<0.05). There was no correlation between expression of TNF a and clinicopathological parameters.3. Effects of doxycycline on proliferation and invasion of adenoid cystic carcinoma cell line SAcc831.1 Morphology: Morphological change was observed by invert microscope. After different concentration of DOXY were added to SAcc83 cells, the cells shrinked and changed to round shape. At the same time, volume of cells contracted obviously. The change was more obvious with increase of time of culture and concentration of Doxy.1.2 Effect of DOXY on cell proliferation: Inhibition of cell proliferation by DOXY was time and dose dependent using method of MTT.\ .3 Effect of DOXY on cell cycle: The cells were blocked at G, stage and the proportion of S stage decreased using flow cytometry. Apoptosis peak was not observed.1.4 Effect of DOXY on activity of MMP-2: SDS-polyactylamide gels detected activity of MMP-2 and MMP-9. The activity of both proteases were inhibited by 10 u g/ml Doxy.1.5 Effect of DOXY on invasive behavior: The area ratio of invasion and PHF were respectively 0.215?.084 and 0.414?.156 in the experimental group and the control group, the difference of which...
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