The CXCR4 inhibitor BL-8040 induces the apoptosis of AML blasts by downregulating ERK, BCL-2, MCL-1 and cyclin-D1 via altered miR-15a/16-1 expression.

CXCR4 is a key player in the retention and survival of human acute myeloid leukemia (AML) blasts in the bone marrow (BM) microenvironment. We studied the effects of the CXCR4 antagonist BL-8040 on the survival of AML blasts, and investigated the molecular mechanisms by which CXCR4 signaling inhibition leads to leukemic cell death. Treatment with BL-8040 induced the robust mobilization of AML blasts from the BM. In addition, AML cells exposed to BL-8040 underwent differentiation. Furthermore, BL-8040 induced the apoptosis of AML cells in vitro and in vivo. This apoptosis was mediated by the upregulation of miR-15a/miR-16-1, resulting in downregulation of the target genes BCL-2, MCL-1 and cyclin-D1. Overexpression of miR-15a/miR-16-1 directly induced leukemic cell death. BL-8040-induced apoptosis was also mediated by the inhibition of survival signals via the AKT/ERK pathways. Importantly, treatment with a BCL-2 inhibitor induced apoptosis and act together with BL-8040 to enhance cell death. BL-8040 also synergized with FLT3 inhibitors to induce AML cell death. Importantly, this combined treatment prolonged the survival of tumor-bearing mice and reduced minimal residual disease in vivo. Our results provide a rationale to test combination therapies employing BL-8040 and BCL-2 or FLT3 inhibitors to achieve increased efficacy of these agents.

Rofecoxib reduces polyp recurrence in familial polyposis.

The long-term (mean of 16.4 +/- 4.2 months) efficacy and safety of rofecoxib (a specific COX-2 inhibitor) in maintaining the colon free of polyps in familial polyposis patients was assessed. Eight patients were treated with rofecoxib 25 mg every day. Sigmoidoscopy/colonoscopy was performed at study entry and every six months. At each endoscopy the number, size, and histological grade of all polyps were assessed, and the polyps were removed. The drug was well tolerated with no significant adverse events throughout the study. A highly significant reduction in the rate of polyp formation (70-100%) was observed in all patients from a mean number of 15.1 +/- 11.7 at baseline to 6.0 +/- 5.8 at one year and 1.6 +/- 1.6 at the end of follow-up (P = 0.016 and 0.008, respectively). No patient developed cancer or high-grade adenoma. In conclusion, Long-term use of rofecoxib is well tolerated and effective in inhibiting polyp formation in polyposis patients.