[The BH3-mimetic GX15-070 synergizes with bortezomib in mantle cell lymphoma by enhancing Noxa-mediated activation of Bak]
>>Blood. 2007 May 15;109(10):4441-9. Epub 2007 Jan 16.
The BH3-mimetic GX15-070 synergizes with bortezomib in mantle cell lymphoma by enhancing Noxa-mediated activation of Bak.
Pérez-Galán P, Roué G, Villamor N, Campo E, Colomer D.
Hematopathology Unit, Department of Pathology, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Spain.
Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma resistant to conventional chemotherapy. The Bcl-2 pathway is deregulated in these tumors and may represent an interesting target for new therapeutic strategies. The new small-molecule pan-Bcl-2 inhibitor GX15-070 mimics BH3-only proteins by binding to multiple antiapoptotic Bcl-2 members. Here we show that GX15-070 induced apoptosis in vitro in MCL cell lines and primary cells from patients with MCL by releasing Bak from Mcl-1 and Bcl-X(L) at short incubation times and low micromolar doses. GX15-070 was effective in cells bearing defective DNA damage-sensor genes or cell-cycle regulators, inducing Bax and Bak conformational changes, mitochondrial depolarization, phosphatidylserine exposure, and caspase-3 activation. Furthermore, GX15-070 synergized with bortezomib, sensitizing MCL cells to low doses of this proteasome inhibitor, by neutralizing bortezomib-induced Mcl-1 accumulation and cooperating with Noxa to induce Bak displacement from this protein. These events led to an increased activation of the mitochondrial apoptotic pathway. Importantly, GX15-070 alone or in combination with bortezomib showed no significant cytotoxic effect in peripheral blood mononuclear cells from healthy donors. All these findings suggest that GX15-070 alone or in combination with bortezomib represents a new attractive therapeutic approach for MCL treatment.<<
>> Proc Natl Acad Sci U S A. 2007 Nov 26; [Epub ahead of print]
Small molecule obatoclax (GX15-070) antagonizes MCL-1 and overcomes MCL-1-mediated resistance to apoptosis.
Nguyen M, Marcellus RC, Roulston A, Watson M, Serfass L, Murthy Madiraju SR, Goulet D, Viallet J, Bélec L, Billot X, Acoca S, Purisima E, Wiegmans A, Cluse L, Johnstone RW, Beauparlant P, Shore GC.
Elevated expression of members of the BCL-2 pro-survival family of proteins can confer resistance to apoptosis in cancer cells. Small molecule obatoclax (GX15-070), which is predicted to occupy a hydrophobic pocket within the BH3 binding groove of BCL-2, antagonizes these members and induces apoptosis, dependent on BAX and BAK. Reconstitution in yeast confirmed that obatoclax acts on the pathway and overcomes BCL-2-, BCL-XL-, BCL-w-, and MCL-1-mediated resistance to BAX or BAK. The compound potently interfered with the direct interaction between MCL-1 and BAK in intact mitochondrial outer membrane and inhibited the association between MCL-1 and BAK in intact cells. MCL-1 has been shown to confer resistance to the BCL-2/BCL-XL/BCL-w-selective antagonist ABT-737 and to the proteasome inhibitor bortezomib. In both cases, this resistance was overcome by obatoclax. These findings support a rational clinical development opportunity for the compound in cancer indications or treatments where MCL-1 contributes to resistance to cell killing.<<
So far as I know, MLNM has no direct interest in this molecule, which recently started PI, and comes from a Canadian company called GeminX.
Cheers, Tuck |
