| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術暨檢驗學系暨研究所 === 98 === It has been reported that Wnt/β-catenin and JAK/STAT pathways are involved in cellular proliferation, survival, apoptosis of leukemia cells. Using shRNA knockdown JAK2 and JAK2 specific inhibitor AG490, we have reported that JAK2 may regulate Wnt/β-catenin in leukemic Jurkat and HEL cells. In the present study, we knocked down β-catenin and its upstream protein GSK3β by shRNA interference. Interestingly, the expression of JAK2/STAT5 pathway related-protein and downstream gene SOCS3 were also affected. It suggests that β-catenin can reversely regulate the JAK2/STAT5 pathway by an unknown mechanism. Using RT-PCR and ELISA method, we found that β-catenin can activate VEGF mRNA expression and the VEGF protein can be detected in its conditioned media. To investigate whether VEGF can activate JAK2/STAT5 pathway through its receptor KDR, we knocked down VEGF or KDR by their shRNA. In addition, β-catenin inhibitor FH535 treatment was also used to inhibit binding between β-catenin and TCF/LEF to reduce VEGF expression. All these three treatments resulted in reduction of VEGF protein and inhibition of JAK2/STAT5 pathway. Taken together, we suggest that accumulation of β-catenin stimulates VEGF expression, which in turn enhances JAK2/STAT5 pathway. VEGF may play as a positive regulator of JAK2/STAT5 pathway and link Wnt/β-catenin and JAK2/STAT5 pathways in leukemia cells.
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