Effects Of Transcription Factor CREB On Mediating Renal Tumorigenesis And Metastasis

Renal cell carcinoma(RCC) is the most common neoplasma of kidney. Cyclic AMP responsive element-binding protein(CREB) is a transcription factor, it can regulate cell cycle, proliferation and migration by targeting related genes. Recent reports demonstrated that CREB is higher expressed in tumor tissue and cells. Our previous reports showed that blocking the CREB binding site at Ser133 significantly inhibited tumor cell growth and the anti-tumor drug-induced cell apoptosis. Therefore,it seemed that CREB is a proto-oncogene. However, little is known about the role of CREB in renal cell carcinoma(RCC) tumorigenesis and progression.In the present study, we first checked the CREB expression in tumor tissue and cells(ACHN, 786-O, OS-RC-2), and compared them with adjacent normal tissues and an immortalized proximal tubule epithelial cell line(HK-2). Second, we decreased the CREB expression by transfection with the dominant negative CREB mutation at Ser133 and si CREB. Third, investigate the role of CREB on RCC cell growth in vitro and in vivo. Fourth, wound healing and transwell assays were used to explore the CREB-mediated cell migration and invasion., and the effects of filopodia on cell migration. Finally, western blot、Bioinformatic softwares and chip assay were used to analyse the molecular mechanism of CREB-meidated RCC migration.Our results showed that the expression level of p CREB in cancer tissues and cells was higher than that in normal adjacent tissues and normal cells. Suppression the p CREB level inhibited kidney cancer formation and growth in vivo. In addition, albation of p CREB level blunted the capabilities of cell migration and invasion in vitro, it was accompanied with the significantly decreased expression of active MMP-2 and MMP-9, the filopodia formation. Furthermore, p CREB-mediates RCC cell metastasis via regulation the expressions of EMT-related protein, including N-cadherin, E-cadherin and fibronectin. Surprisedly, we found that p CREB-mediated RCC cell metastasis was not combined with vimentin(a marker of EMT), because no changes about the expression and location were revealed in the experiment. Bioinformatic softwares explained the possible reason is its promoter not containing the CRE sequence. And Chip revealed that CREB interacted with fibronectin, don’t interact with vimentin.Therefore, these data suggested that the phospharylated level of CREB at 133 site influces the carcinogenesis and metastasis by regulating the filopodia formation and EMT-related protein expression, whereas, vimentin was not included in this progress.