studies were carried out in drug sensitive

CEBP b directly binds to the CEBP b binding site in the miR 145 promoter These above indicate that LIP is sufficient to suppress p53 mediated miR 145 induction. Since LIP consists of two domains, DNA binding domain and dimerization domain, we asked which domain is required for this suppression by deletion of either two domains or Imatinib dimerization domain alone. Deletion of both domains completely abolished the suppression activity as detected by the miR 145 promoter luciferase reporter as well as by the miR 145 prompter GFP reporter. On the other hand, deletion of dimerization domain partially impaired this suppression activity. Similarly, real time RT?PCR also indicated that the DNA binding domain is critical. Finally, ChIP assays confirmed that C/EBP b directly interacted with the miR 145 promoter. RSV suppresses Urogenital pelvic malignancy phosphorylation of C/EBP b through Akt pathway We have previously shown that miR 145 is a downstream target of Akt, suppression of Akt by serum starvation or PI3 K inhibitor LY29 induces miR 145 expression in a p53 dependent manner. However, this study showed that RSV was able to induce miR 145 in breast cancer cells carrying mutant p53. Moreover, RSV has been previously shown to suppress Akt activity. Therefore, we determined whether Akt is a molecular link underlying the RSV induced miR 145 expression in tumor cells carrying mutant p53. We first examined the constitutive levels of Akt and pAkt in MDA MB 231, BT 549 and MCF 7 cells, BT 549 cells expressed a relatively higher level of pAkt than the other two cell lines. As expected, RSV caused downregulation of pAkt in BT 549 and MDA MB 231 cells, however, no obvious reduction was seen in MCF 7 cells in 50 or 100 mM. Importantly, we pifithrin-? detected downregulation of p LAP 2 in both MDA MB 231 and BT 549 cells, this reduction in MCF 7 cells was not as obvious as in the other two cell lines. Immunocytochemistry also showed downregulation of p C/EBP b by RSV in MDA MB 231 cells. Since c Myc is a major target for miR 145, which may in part account for miR 145 as a tumor suppressor, we also examined the effect of RSV on Myc expression. As expected, RSV reduced c Myc level, associated with downregulation of p C/EBP b, further suggesting the role of p C/EBP b in suppression of miR 145. Finally, ChIP assays indicated that both LY29 and RSV suppressed C/EBP b binding to the miR 145 promoter. Together, these suggest that RSV induces miR 145 through suppression of pAkt and phosphorylation of C/EBP b in the mutant p53 background. It is well known that microRNAs can play a critical role in human malignancy. As a tumor suppressor, miR 145 is able to suppress tumor growth and metastasis by targeting a number of oncogenic genes. Moreover, miR 145 has been implicated in repression of pluripotency in human embryonic stem cells by negative regulation of key transcription factors such as OCT4, SOX2 and KLF4.