Purpose: The expression of fibulin-5 was investigated in urothelial carcinomas of bladder and in normal bladder samples. The effects of fibulin-5 on cell proliferation, motility, and invasion were further explored in bladder cancer cell line 5637.
Materials and methods: The expression of fibulin-5 in 20 bladder carcinoma samples and 7 normal bladder samples were detected by Western blot. Fibuin-5 cDNA was cloned into p-EGFP-N1 vector and transfected into bladder cancer cell line 5637. Growth curves were estimated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay and cell number count. The migration and invasion of the transfected cells and the control cells were measured by Boyden chamber assay.
Results: Compared with 1.16 ± 0.28 in the normal control, the mean ± SD expression of fibulin-5 in low grade tumors and high grade tumors were 0.57 ± 0.32 and 0.44 ± 0.42 (P = 0.002 and P = 0.018, respectively), while the expression in Ta-T1 tumors and T2+ tumors were 0.55 ± 0.31 and 0.49 ± 0.43 (P = 0.002 and P = 0.015, respectively). The differences between low grade and high grade tumors or Ta-T1 and T2+ tumors were not statistically significant (P = 0.362 and P = 0.589, respectively). The growth rate of the fibulin-5 transfected GFP-F5 cells was remarkably reduced than that of the untransfected cells or the empty vector transfected GFP-t cells. Besides, compared with control cells, the GFP-F5 cells showed significant inhibition of cell invasion with slight inhibition of cell migration.
Conclusions: Fibulin-5 is down-regulated in urothelial carcinoma of bladder and acts as a tumor suppressor gene by inhibiting proliferation and invasion of bladder cancer cells.
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