Effect of L-arginine on human colon carcinoma cell line LS174 through NO pathway and the mechanism / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effects of L-arginine (L-Arg) on human colon carcinoma cell line LS174 through NO pathway and the mechanism.</p><p><b>METHODS</b>LS174 cells were cultured in the presence of L-Arg at different concentrations for different time. MTT assay was employed to evaluate the cell proliferation, and the cell morphological changes were observed by optical and electron microscopy. The apoptosis of L-Arg-treated cells was observed by the Annexin V/PI staining. The expression levels of VEGF, COX-2, p53, bcl-2 and bax in the cells were determined using Western blotting and immunocytochemical staining.</p><p><b>RESULTS</b>L-Arg promoted the growth of LS174 cells at a low concentration (0.125 mmol/L) and inhibited the cell growth at higher concentrations (0.5, 2, 8, and 32 mmol/L). Under electron microscope, ultrastructual changes in the cytoplasm and nuclei of LS174 cells were observed 48 h after exposure to L-Arg. Some of the cells showed morphological changes characteristic of cell apoptosis such as cell size reduction, condensation and margination of the nuclear chromatin. Low concentration of L-Arg resulted in a cell apoptosis rate of 2.29%, as compared with the rate of 2.84% in the control group; at higher concentrations, L-Arg caused significantly increased cell apoptosis rates to 26.88%, 28.95%, 63.36%, and 84.51%, respectively. In cells treated with a low concentration of L-Arg, the expressions of VEGF and COX-2 were increased as compared with those in the control cells; higher concentrations of L-Arg obviously decreased the expressions of p53 and bcl-2 and increased the expression of bax.</p><p><b>CONCLUSION</b>Low-concentration L-Arg can promote the growth of LS174 cells probably by up-regulating VEGF and COX-2 protein under the influence of NO, the metabolite of L-Arg. The inhibitory effect of high concentrations of L-Arg is probably mediated by inducing cell apoptosis via NO. The mechanism of L-Arg- induced cell apoptosis may be related to the up-regulation of bax protein and the down-regulation of p53 and bcl-2 proteins.</p>

The expression and significance of hTERT and P53 in thyroid carcinoma / 西安交通大学学报·英文版

Objective: To determine the expression of human telomerase reverse transcriptase (hTERT) and P53 in thyroid carcinoma and its relationship with development and prognosis of the carcinoma. Methods: Totally 90 cases of thyroid specimens (60 thyroid carcinomas, 10 thyroid adenomas, 10 goitres and 10 normal thyroid tissues) were studied by SP immunohistochemical method. Results: Positive immunoreactivity of hTERT and P53 was higher in thyroid carcinoma (P<0.05). The positive rates of hTERT and P53 were higher in undifferentiated carcinomas, carcinomas with lymph nodes metastasis or at stage III + IV than in well-differentiated carcinomas, carcinomas without lymph nodes metastasis or at stage I + II (P<0.05). The expression of hTERT was significantly related with that of P53 (P<0.05). Conclusion: Over-expressed hTERT and P53 may be related to the carcinogenesis and progression of thyroid carcinoma and hTERT expression is related to P53 protein. Examination of expression of hTERT and P53 proteins may be helpful to judge the thyroid cancer's behavior and prognosis.