Selective leukemic-cell killing by a novel functional class of thalidomide analogs

Abstract

Using a novel cell-based assay to profile transcriptional pathway targeting, we have identified a new functional class of thalidomide analogs with distinct and selective antileukemic activity. These agents activate nuclear factor of activated T cells (NFAT) transcriptional pathways while simultaneously repressing nuclear factor-B (NF-B) via a rapid intracellular amplification of reactive oxygen species (ROS). The elevated ROS is associated with increased intracellular free calcium, rapid dissipation of the mitochondrial membrane potential, disrupted mitochondrial structure, and caspase-independent cell death. This cytotoxicity is highly selective for transformed lymphoid cells, is reversed by free radical scavengers, synergizes with the antileukemic activity of other redox-directed compounds, and preferentially targets cells in the S phase of the cell cycle. Live-cell imaging reveals a rapid drug-induced burst of ROS originating in the endoplasmic reticulum and associated mitochondria just prior to spreading throughout the cell. As members of a novel functional class of "redoxreactive" thalidomides, these compounds provide a new tool through which selective cellular properties of redox status and intracellular bioactivation can be leveraged by rational combinatorial therapeutic strategies and appropriate drug design to exploit cell-specific vulnerabilities for maximum drug efficacy. IntroductionThalidomide is a synthetic glutamic acid derivative originally marketed as a sedative and antiemetic in 1954. 1,2 However, in 1961 it was quickly withdrawn from distribution when its teratogenic properties were discovered. 1,2 Several years later the serendipitous finding that thalidomide could allay the symptoms of erythema nodosum led to its re-emergence as a treatment for various proinflammatory and autoimmune conditions. 3 Although many of the anti-inflammatory properties of thalidomide have been linked to its ability to repress tumor necrosis factor-␣ (TNF-␣) expression, 4 the mechanisms underlying most of its therapeutic effects, including its ability to costimulate T cells, 5 remained a mystery. In 1994, speculation that thalidomide teratogenicity is linked to the repression of angiogenesis 6 spawned a new wave of clinical investigations that expanded the use of thalidomide for the treatment of various malignancies, including multiple myeloma, melanoma, renal-cell carcinoma, and prostate cancer. 1,2 The therapeutic promise of thalidomide became a motivation to develop more effective derivatives with reduced toxicity. Several chemical classes of compounds were subsequently developed. One group, referred to as immunomodulatory drugs (IMiDs), 2 was identified because of its potential to promote T-cell costimulatory activity. A second group, referred to as the selective cytokine inhibitory drugs (SelCIDs), were found to be potent phosphodiesterase 4 (PDE4) inhibitors. 7 Both groups repress TNF-␣ expression. IMiDs are currently in phase 2 and phase 3 clinical trials for multiple myeloma, metastatic melanoma, and prosta...

Combinatorial Antileukemic Disruption of Oxidative Homeostasis and Mitochondrial Stability by the Redox Reactive Thalidomide 2-(2,4-Difluoro-phenyl)-4,5,6,7-tetrafluoro-1H-isoindole-1,3(2H)-dione (CPS49) and Flavopiridol

“…Both CPS49 and flavopiridol have been shown to alter the redox status of leukemic cells (Decker et al, 2001;Ge et al, 2006). To assess the selective combined influence of CPS49 and flavopiridol on the redox properties of primary and transformed cells the intracellular levels of ROS and GSH were assessed in cells treated with different combinations of flavopiridol and CPS49 after 1-and 16-h incubations, respectively (Fig.…”

“…These compounds inhibit NF-B activity, increase intracellular calcium, and produce a rapid elevation of intracellular ROS that results in dissipation of the mitochondrial membrane potential and subsequent caspase-independent necrotic cell death (Ge et al, 2006). The shared targeting of both NF-B activity and mitochondrial function by flavopiridol and the redoxreactive thalidomides suggested that the combinatorial use of these agents may produce more effective tumor cell killing.…”

“…We have described the identification and characterization of a novel functional class of thalidomide analogs referred to as redox-reactive thalidomides (Ge et al, 2006). These compounds inhibit NF-B activity, increase intracellular calcium, and produce a rapid elevation of intracellular ROS that results in dissipation of the mitochondrial membrane potential and subsequent caspase-independent necrotic cell death (Ge et al, 2006).…”

“…The shared targeting of both NF-B activity and mitochondrial function by flavopiridol and the redoxreactive thalidomides suggested that the combinatorial use of these agents may produce more effective tumor cell killing. CPS49 is a redox-reactive thalidomide analog that has recently been shown to have effective cytotoxicity against lymphocytic leukemia cells, multiple myeloma, lung cancer, prostate cancer and endothelial cells (Ng et al, 2003(Ng et al, , 2004Kumar et al, 2005;Ge et al, 2006;Warfel et al, 2006). Like flavopiridol, it has been shown to have antiangiogenic potential (Ng et al, 2003;Newcomb, 2004).…”

Talidomid analógok hatásának vizsgálata jelölésmentes szűrőrendszeren és a hepatocelluláris karcinóma egér modelljén

“…Előzetesen megállapítottuk, hogy a talidomid analógjaink bejutva a sejtbe kölcsönhatásba lépnek a lipid cseppecskékkel és az endoplazmatikus retikulummal, ezért megvizsgáltuk, hogy az Ac-915 és az Ac-2010 anyagoknak van-e oxidatív stresszt kiváltó hatása, ahogy azt Ge és mtsai munkájuk során találták az ún. "redox-reaktív" talidomid analógokról [85]. Megmértük a két talidomid analógunkkal való kezelést követően a ROS szintet Hep3B sejtekben (9.a ábra).…”