A series of novel cyclic marinopyrroles were designed and synthesized. Their activity to disrupt the binding of the pro-apoptotic protein, Bim, to the pro-survival proteins, Mcl-1 and Bcl-x_L, was evaluated using ELISA assays. Both atropisomers of marinopyrrole A (1) show similar potency. A tetrabromo congener 9 is two-fold more potent than 1. Two novel cyclic marinopyrroles (3 and 4) are two- to seven-fold more potent than 1.

A series of novel marinopyrroles with sulfide and sulphone spacers were designed and synthesized. Their activity to disrupt the binding of the pro-apoptotic protein, Bim, to the pro-survival proteins, Mcl-1 and Bcl-xL, was evaluated using ELISA assays. Fluorescence-quenching (FQ) assays confirmed the direct binding of marinopyrroles to Mcl-1. Benzyl- and benzyl methoxy-containing sulfide derivatives 4 and 5 were highly potent dual Mcl-1/Bim and Bcl-xL/Bim disruptors (IC₅₀ values of 600 and 700 nM), whereas carboxylate-containing sulfide derivative 9 exhibited 16.4-fold more selectivity for disrupting Mcl-1/Bim over Bcl-xL/Bim binding. In addition, a nonsymmetrical marinopyrrole 12 is as equally potent as the parent marinopyrrole A (1) for disrupting both Mcl-1/Bim and Bcl-xL/Bim binding. Some of the derivatives were also active in intact human breast cancer cells where they reduced the levels of Mcl-1, induced programd cell death (apoptosis) and inhibited cell proliferation.

Both Akt 2 and acid ceramidase (ASAH1) are found aberrantly overexpressed in cancer cells, but whether these two enzymes cooperate to induce malignant transformation is not known. We found that in immortalized, non-transformed cells, ectopic co-expression of Akt2 and ASAH1 is significantly more effective than expression of each gene alone at inducing cell invasion and at conferring resistance to apoptosis. Consistent with these observations, siRNA-mediated depletion of both Akt2 and ASAH1 is much more potent than depleting each alone at inhibiting cell viability/proliferation and cell invasion. Furthermore, pharmacological inhibitors of Akt (TCN or MK-2206) and ASAH1 (B13) synergize to inhibit cell viability/proliferation, and combinations of these drugs are more effective than single-agent treatments at inhibiting cell invasion. Taken together, the results suggest that these two enzymes cooperate to induce malignant transformation and warrant further preclinical studies to evaluate the potential of combining inhibitors of Akt and ASAH1 to treat cancer.