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ABSTRACT: Multidrug resistance (MDR) is a major hurdle in the treatment of cancer and there is a pressing need for new therapies. We have recently developed ethyl 2-amino-6-(3,5-dimethoxyphenyl)-4-(2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (CXL017), derived from a dual inhibitor of Bcl-2 and SERCA proteins - sHA 14-1, with selective cytotoxicity towards MDR cancer cell lines in vitro. In this study, we present new evidence for its therapeutic potential in treatment of MDR cancers and offer mechanistic insights towards its preferential targeting of drug resistant cancer. CXL017 selectively suppressed the growth of tumors derived from the MDR cancer cell line, HL60/MX2, in vivo. In addition, even after chronic exposure to CXL017, HL60/MX2 failed to develop stable resistance to CXL017, whereas it acquired > 2000-fold resistance to cytarabine (Ara-C) - the major first-line chemotherapy for the treatment of acute myeloid leukemia (AML). Remarkably, instead of acquiring further cross-resistance, HL60/MX2 cells exposed to CXL017 were re-sensitized to standard therapies (10 to 100-fold). Western blotting analyses revealed that CXL017 exposure significantly down-regulated Mcl-1 and Bax and up-regulated Noxa, Bim, Bcl-XL, SERCA2, and SERCA3 proteins, along with a reduction in endoplasmic reticulum (ER) calcium content. Given the well-established functions of Bcl-2 family proteins and ER calcium in drug resistance, our results suggest that the down-regulation of Mcl-1 and the up-regulation of Noxa and Bim along with the decrease in ER calcium content are likely responsible for CXL017 induced re-sensitization of MDR cancer cells. These data also demonstrate the unique potential of CXL017 to overcome MDR in cancer treatment.
ACS Chemical Biology 10/2012; · 6.45 Impact Factor
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ABSTRACT: Multidrug resistance (MDR) in cancer is a phenomenon in which administration of a single chemotherapeutic agent causes cross-resistance of cancer cells to a variety of therapies even with different mechanisms of action. Development of MDR against standard therapies is a major challenge in the treatment of cancer. Previously we have demonstrated a unique ability of CXL017 (5) to selectively target MDR cancer cells and synergize with mitoxantrone (MX) in HL60/MX2 MDR cells. Here we expand its scope and demonstrate that 5 can synergize with both vincristine and paclitaxel in three different MDR cell lines (HL60/DNR, K562/HHT300, and CCRF-CEM/VLB100). We also demonstrate that 5 has potent cytotoxicity in the NCI-60 panel of cell lines with an average IC(50) of 1.04 μM. In addition, 5 has a unique mechanism of action in comparison with standard agents in the NCI database based on COMPARE analysis. Further structure-activity relationship study led to the development of a more potent analogue, compound 7d, with an IC(50) of 640 nM in HL60/MX2. Additionally, one enantiomer of 5 is 13-fold more active than the less active enantiomer. Taken together, our study has led to the discovery of a series of analogues that selectively target drug-resistant cancer cells with the potential for the treatment of drug-resistant cancers.
Journal of Medicinal Chemistry 08/2011; 54(16):5937-48. · 4.80 Impact Factor
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ABSTRACT: Rapid development of multiple drug resistance against current therapies is a major barrier in the treatment of cancer. Therefore, anticancer agents that can overcome acquired drug resistance in cancer cells are of great importance. Previously, we have demonstrated that ethyl 2-amino-4-(2-ethoxy-2-oxoethyl)-6-phenyl-4H-chromene-3-carboxylate (5a, sHA 14-1), a stable analogue of ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (6, HA 14-1), mitigates drug resistance and synergizes with a variety of cancer therapies in leukemia cells. Structure-activity relationship (SAR) studies of 5a guided the development of ethyl 2-amino-6-(3',5'-dimethoxyphenyl)-4-(2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (5q, CXL017), a compound with low micromolar cytotoxicity against a wide-range of hematologic and solid tumor cells. More excitingly, our studies of 5q in camptothecin (CCRF-CEM/C2) and mitoxantrone (HL-60/MX2) resistant cancer cells highlight its ability to selectively kill drug-resistant cells over parent cancer cells. 5q inhibits tumor cell growth through the induction of apoptosis, with detailed mechanism of its selectivity toward drug-resistant cancer cells under investigation. These results suggest that 5q is a promising candidate for treatment of cancers with multiple drug resistance.
Journal of Medicinal Chemistry 10/2009; 52(19):5937-49. · 4.80 Impact Factor
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David Hermanson,
Sadiya N Addo,
Anna A Bajer,
Jonathan S Marchant, Sonia Goutam Kumar Das,
Balasubramanian Srinivasan,
Fawaz Al-Mousa,
Francesco Michelangeli,
David D Thomas,
Tucker W Lebien,
Chengguo Xing
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ABSTRACT: HA 14-1 is a small-molecule Bcl-2 antagonist that promotes apoptosis in malignant cells, but its mechanism of action is not well defined. We recently reported that HA 14-1 has a half-life of only 15 min in vitro, which led us to develop a stable analog of HA 14-1 (sHA 14-1). The current study characterizes its mode of action. Because of the antiapoptotic function of Bcl-2 family proteins on the endoplasmic reticulum (ER) and mitochondria, the effect of sHA 14-1 on both organelles was evaluated. sHA 14-1 induced ER calcium release in human leukemic cells within 1 min, followed by induction of the ER stress-inducible transcription factor ATF4. Similar kinetics and stronger intensity of ER calcium release were induced by the sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibitor thapsigargin, accompanied by similar kinetics and intensity of ATF4 induction. sHA 14-1 directly inhibited SERCA enzymatic activity but had no effect on the inositol triphosphate receptor. Evaluation of the mitochondrial pathway showed that sHA 14-1 triggered a loss of mitochondrial transmembrane potential (Delta psi m) and weak caspase-9 activation, whereas thapsigargin had no effect. (R)-4-(3-Dimethylamino-1-phenylsulfanylmethyl-propylamino)-N-{4-[4-(4'-chloro-biphenyl-2-ylmethyl)-piperazin-1-yl]-benzoyl}-3-nitrobenzenesulfonamide (ABT-737), a well established small-molecule Bcl-2 antagonist, rapidly induced loss of Delta psi m and caspase-9 activation but had no effect on the ER. The pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone had some protective effect on sHA 14-1-induced cell death. These collective results suggest a unique dual targeting mechanism of sHA 14-1 on the apoptotic resistance machinery of tumor cells that includes antiapoptotic Bcl-2 family proteins and SERCA proteins.
Molecular pharmacology 07/2009; 76(3):667-78. · 4.53 Impact Factor
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ABSTRACT: HA 14-1, a small-molecule antagonist against anti-apoptotic Bcl-2 proteins, was demonstrated to induce selective cytotoxicity toward malignant cells and to overcome drug resistance. Due to its poor stability and the reactive oxygen species (ROS) generated by its decomposition, chemical modification of HA 14-1 is needed for its future development. We have synthesized a stabilized analog of HA 14-1--sHA 14-1, which did not induce the formation of ROS. As expected from a putative antagonist against anti-apoptotic Bcl-2 proteins like HA 14-1, sHA 14-1 disrupted the binding interaction of a Bak BH3 peptide with Bcl-2 or Bcl-X(L) protein, inhibited the growth of tumor cells through the induction of apoptosis, and circumvented the drug resistance induced by the over-expression of anti-apoptotic Bcl-2 and Bcl-X(L) proteins. Interestingly, the impairment of extrinsic apoptotic pathway induced moderate resistance to sHA 14-1. The moderate resistance suggested that sHA 14-1 generated part of its apoptotic stress through the intrinsic pathway, possibly through its antagonism against anti-apoptotic Bcl-2 proteins. The resistance indicated that sHA 14-1 generated apoptotic stress through the extrinsic apoptotic pathway as well. The ability of sHA 14-1 to induce apoptotic stress through both pathways was further supported by the synergism of sHA 14-1 towards the cytotoxicities of Fas ligand and dexamethasone in Jurkat cells. Taken together, these findings suggest that sHA 14-1 may represent a promising candidate for the treatment of drug-resistant cancers either as a monotherapy or in combination with current cancer therapies.
Cancer Letters 03/2008; 259(2):198-208. · 4.24 Impact Factor
