Coadministration of Histone Deacetylase Inhibitors and Perifosine Synergistically Induces Apoptosis in Human Leukemia Cells through Akt and ERK1/2 Inactivation and the Generation of Ceramide and Reactive Oxygen Species

Abstract

Interactions between histone deacetylase inhibitors (HDACIs) and the alkyl-lysophospholipid perifosine were examined in human leukemia cells. Coadministration of sodium butyrate, suberoylanilide hydroxamic acid (SAHA), or trichostatin with perifosine synergistically induced mitochondrial dysfunction (cytochrome c and apoptosis-inducing factor release), caspase-3 and -8 activation, apoptosis, and a marked decrease in cell growth in U937 as well as HL-60 and Jurkat leukemia cells. These events were associated with inactivation of extracellular signal-regulated kinase (ERK) 1/ 2 and Akt, p46 c-jun-NH 2 -kinase (JNK) activation, and a pronounced increase in generation of ceramide and reactive oxygen species (ROS). They were also associated with upregulation of Bak and a marked conformational change in Bax accompanied by membrane translocation. Ectopic expression of Bcl-2 delayed but was ultimately ineffective in preventing perifosine/HDACI-mediated apoptosis. Enforced expression of constitutively active mitogen-activated protein kinase kinase (MEK) 1 or myristoylated Akt blocked HDACI/perifosine-mediated ceramide production and cell death, suggesting that MEK/ERK and Akt inactivation play a primary role in these phenomena. However, inhibition of JNK activation (e.g., by the JNK inhibitor SP600125) did not attenuate sodium butyrate/perifosineinduced apoptosis. In addition, the free radical scavenger Nacetyl-L-cysteine attenuated ROS generation and apoptosis mediated by combined treatment. Finally, the acidic sphingomyelinase inhibitor desipramine attenuated HDACI/ perifosine-mediated ceramide and ROS production as well as cell death. Together, these findings indicate that coadministration of HDACIs with perifosine in human leukemia cells leads to Akt and MEK/ERK disruption, a marked increase in ceramide and ROS production, and a striking increase in mitochondrial injury and apoptosis. They also raise the possibility that combining these agents may represent a novel antileukemic strategy. (Cancer Res 2005; 65(6): 2422-32)

Potentiation of the anticancer effect of valproic acid, an antiepileptic agent with histone deacetylase inhibitory activity, by the kinase inhibitor Staurosporine or its clinically relevant analogue UCN-01

“…Not surprising, however, STP or UCN-01 exerted a potent inhibitory effect on PKC activity indicated by a profound time-and dosedependent depletion of p-adducin levels in treated H460 or TE12 cells. Grant and co-workers have observed reduction of MEK/ ERK1/2 activity in cells treated with combinations of HDACIs and other kinase inhibitors, including perifosine, 17-AAG or LY294002 that mediated substantial apoptosis (Dai et al, 2001;Rahmani et al, 2003bRahmani et al, , 2005. Downregulation of MEK/ERK1/2 plays an important role in the synergistic induction of apoptosis as forced expression of constitutively active MEK abrogates the cytotoxic effects of these drug combinations (Dai et al, 2001;Rahmani et al, 2003bRahmani et al, , 2005.…”

“…Grant and co-workers have observed reduction of MEK/ ERK1/2 activity in cells treated with combinations of HDACIs and other kinase inhibitors, including perifosine, 17-AAG or LY294002 that mediated substantial apoptosis (Dai et al, 2001;Rahmani et al, 2003bRahmani et al, , 2005. Downregulation of MEK/ERK1/2 plays an important role in the synergistic induction of apoptosis as forced expression of constitutively active MEK abrogates the cytotoxic effects of these drug combinations (Dai et al, 2001;Rahmani et al, 2003bRahmani et al, , 2005. It was further indicated that LY294002 enhances HDACI cytotoxicity via downregulation of MEK/ERK1/2 activity but not via abrogation of Akt activation (Rahmani et al, 2003b).…”

Selective anti-leukaemic activity of low-dose histone deacetylase inhibitor ITF2357 on AML1/ETO-positive cells

“…Indeed, HDAC have multiple non-histone targets and may induce apoptosis via acetylation of transcription factors such as E2F-1 (Tan et al, 2006). Furthermore, secondary epigenetic mechanisms may mediate lethality induced by HDACi, including reactive oxygen species generation, NFkB activation, disruption of G2 and mitotic checkpoints, activation of JNK and inactivation of ERK1/2, upregulation of proapoptotic genes and downregulation of antiapoptotic genes Rahmani et al, 2005). On the other hand, in the experiments reported here, a low dose of ITF2357 (0.1 mM), which induces significant histone acetylation in all cells tested, succeeded in leading to apoptosis of AML1/ETO-positive cells only: Kasumi-1, AML1/ ETO-inducible U937 and AML1/ETO-positive primary cells.…”

The alkylphospholipid perifosine induces apoptosis of human lung cancer cells requiring inhibition of Akt and activation of the extrinsic apoptotic pathway

“…Perifosine has also been shown to induce p21 expression leading to cell cycle arrest (6). In addition, perifosine, in combination with other antitumor agents such as the PDK1 inhibitor, UCN-01 (7), histone deacetylase inhibitors (8), and the chemotherapeutic agent etoposide (9), show synergistic antitumor effects.…”