Synergistic effects of PI3K inhibition and pioglitazone against acute promyelocytic leukemia cells.

BACKGROUND: Although pioglitazone, a well-known anti-diabetic agent, has recently established itself as a pillar of cancer treatment, its therapeutic value could be attenuated by the aberrant activation of the PI3K/Akt pathway. AIM: To evaluate whether the PI3K/Akt suppression in leukemic cells could potentiate the anti-leukemic effects of pioglitazone. METHODS: To assess the anti-leukemic effects of PI3K/Akt inhibitors on anti-leukemic effects of pioglitazone, we used MTT and trypan blue assays. Flow cytometric analysis and qRT-PCR were also applied to evaluate cell cycle and apoptosis. RESULT: The resulting data revealed that upon PPARγ stimulation in different leukemic cell lines using pioglitazone, the survival and the proliferative capacity of the cells were significantly halted. Then, we evaluated the impact of the PI3K/Akt axis on the effectiveness of the drug in the most sensitive leukemic cell line; NB4 cells. Our results showed that treatment of NB4 cells with the PI3K inhibitors increased the sensitivity of leukemic cells to pioglitazone to the degree that even lower concentrations of the agent succeeded to induce apoptotic as well as the anti-proliferative effects. Moreover, it seems that PI3K inhibition could potentiate the anti-leukemic effect of pioglitazone through induction of p21-mediated sub-G1 cell cycle arrest and altering the balance between the pro-and anti-apoptotic genes. CONCLUSION: This study sheds light on the significance of the PI3K/Akt pathway in APL cell sensitivity to pioglitazone and proposed that the presence of the PI3K inhibitor in the therapeutic regimen containing pioglitazone could be promising in the treatment of this malignancy.

Alteration of PPAR-GAMMA (PPARG; PPARγ) and PTEN gene expression in acute myeloid leukemia patients and the promising anticancer effects of PPARγ stimulation using pioglitazone on AML cells.

BACKGROUND: In the new era of tailored cancer treatment strategies, finding a molecule to regulate a wide range of intracellular functions is valuable. The unique property of nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ; PPARG) in transmitting the anti-survival signals of the chemotherapeutic drugs has fired the enthusiasm into the application of this receptor in cancer treatment. OBJECTIVES: We aimed to investigate the expression of PPARγ and one of its downstream targets PTEN in non-M3 acute myeloid leukemia (AML) patients. We also investigated the therapeutic value of PPARγ stimulation using pioglitazone in the AML-derived U937 cell line. METHODS: The blood samples from 30 patients diagnosed with non-M3 AML as well as 10 healthy individuals were collected and the mRNA expression levels of PPARγ and PTEN were evaluated. Additionally, we used trypan blue assay, MTT assay, and flow cytometry analysis to evaluate the anti-leukemic effects of pioglitazone on U937 cells. RESULTS: While PTEN was significantly downregulated in AML patients as compared to the control group, the expression of PPARγ was increased in the patients' group. The expression level of PPARγ was also negatively correlated with PTEN; however, it was not statistically significant. Besides, PPARγ stimulation using pioglitazone reduced survival and proliferative capacity of U937 cells through inducing apoptosis and suppression of cell transition from the G1 phase of the cell cycle. CONCLUSION: The results of the present study shed more light on the importance of PPARγ and its stimulation in the therapeutic strategies of AML.

Suppression of proteasome induces apoptosis in APL cells and increases chemo-sensitivity to arsenic trioxide: Proposing a perception in APL treatment.

In the last three decades, the pathogenesis of acute promyelocytic leukemia (APL) has been mostly studied with regard to the oncogenic role of PML/RAR fusion protein; however, the latest discoveries have stated that the concerns with the treatment of APL patients would not be resolved until the role of aberrant networks is overlooked. The present study was designed to evaluate the anti-cancer property of second-generation of the proteasome inhibitors carfilzomib (CFZ) on APL-derived NB4 cells. Our results showed that pharmacologic targeting of proteasome in NB4 reduced the proliferative rate of malignant cells through a c-Myc-mediated G2/M cell cycle arrest. Moreover, we found that the suppression of proteasome was coupled with the induction of apoptotic NB4 cell death, which is probably mediated through down-regulation of anti-apoptotic target genes. Interestingly, our results suggested that the suppression of the autophagy system using chloroquine could serve as a mechanism through which the cytotoxicity of CFZ in APL cells was ameliorated. Finally, and consistent with the favorable efficacy of single agent of CFZ, we also noted an intensifying effect of the inhibitor on the anti-leukemic activity of arsenic trioxide (ATO) when it was used in combination. Overall, this study suggests that pharmaceutical targeting of proteasome using CFZ, either as a single agent or in combination with ATO, could be a promising mechanism through which the obstacle on the way of APL would be tackled; however, further investigations are needed to determine the advantages of the inhibitor in clinical applications.

Stimulation of Peroxisome Proliferator-Activated Receptor-Gamma (PPARγ) using Pioglitazone Decreases the Survival of Acute Promyelocytic Leukemia Cells through Up-Regulation of PTEN Expression.

BACKGROUND: The intertwining between cancer pathogenesis and aberrant expression of either oncogenes or tumor suppressor proteins ushered the cancer therapeutic approaches into a limitless road of modern therapies. For the nonce and among the plethora of promising anticancer agents, intense interest has focused on pioglitazone, a first in-class of Thiazolidinedione (TZD) drugs that is currently used to treat patients with diabetes. OBJECTIVE: Intrigued by the overexpression of PPARγ in Acute Promylocytic Leukemia (APL), this study was designed to investigate the effects of pioglitazone in APL-derived NB4 cells. METHODS: To assess the anti-leukemic effect of pioglitazone on myeloid leukemia cell lines, we used MTT and trypan blue assays. Given the higher expression level of PPARγ in NB4 cells, we then expanded our experiments on this cell line. To ascertain the molecular mechanism action of pioglitazone in APL-derived NB4 cells, we evaluated the expression levels of a large cohort of target genes responsible for the regulation of apoptosis, autophagy and cell proliferation. Afterward, to examine whether there is a correlation between PPARγ and the PI3K signaling pathway, the amount of Akt phosphorylation was evaluated using western blot analysis. RESULTS: Our results showed that pioglitazone exerted its cytotoxic effect in wild-type PTEN-expressing NB4 cells, but not in leukemic K562 cells harboring mutant PTEN; suggesting that probably this member of TZD drugs induced its anti-leukemic effects through a PTEN-mediated manner. Moreover, we found that not only pioglitazone reduced the survival rate of NB4 through the induction of p21-mediated G1 arrest, also elevated the intracellular level of Reactive Oxygen Species (ROS) which was coupled with upregulated FOXO3a. Notably, this study proposed for the first time that the stimulation of autophagy as a result of the compensatory activation of PI3K pathway may act as a plausible mechanism through which the anti-leukemic effect of pioglitazone may be attenuated; suggestive of the application of either PI3K or autophagy inhibitors along with pioglitazone in APL. CONCLUSION: By suggesting a mechanistic pathway, the results of the present study shed more light on the favorable anti-leukemic effect of pioglitazone and suggest it as a promising drug that should be clinically investigated in APL patients.

Activation of PPARγ intensified the effects of arsenic trioxide in acute promyelocytic leukemia through the suppression of PI3K/Akt pathway: Proposing a novel anticancer effect for pioglitazone.

The indulgent success of arsenic trioxide (ATO) in the induction of complete remission in acute promyelocytic leukemia (APL) patients has accommodated this agent into the therapeutic protocols. However, the intrusion of unfavorable side effects had put an unanswered question on the way of the application of this agent; whether the benefits of ATO may outweigh its drawbacks. In this study, we found that when ATO is accompanied by an activator of peroxisome proliferator-activated receptors gamma (PPARγ), even the lower concentrations could induce significant inhibitory effects on the survival of NB4 through diminishing the ability of the cells to replicate DNA in the S phase of cell cycle. We also found that through suppression of the PI3K pathway, the combination of pioglitazone and ATO provided a signal through which the induction of apoptotic cell death was enhanced probably via the elevation of reactive oxygen species (ROS). With respect to the tight connection between PI3K pathway and autophagy system and given to the inhibitory effect of pioglitazone-plus-ATO on PI3K, we found that the combination of these agents not only suppressed the expression of autophagy-related genes, but also their efficacy was augmented when autophagy was inhibited in NB4; clarifying the encouraging role of autophagy in the survival maintenance of APL cells. In conclusion, given the significant efficacy as well as the safety profile of pioglitazone in potentiating the anticancer effects of chemotherapeutic drugs, the present study suggests it as a promising agent to be used in adjuvant strategy for the treatment of APL.

PI3K Abrogation Using Pan-PI3K Inhibitor BKM120 Gives Rise to a Significant Anticancer Effect on AML-Derived KG-1 Cells by Inducing Apoptosis and G2/M Arrest

Objective: The association between PI3K overexpression and the acquisition of chemoresistance has attracted tremendous attention to this axis as an appealing target to revolutionize the conventional treatment strategies of human cancers. In the present study, we aimed to survey the inhibitory impact of the pan-PI3K inhibitor BKM120 on both cellular and molecular aspects of acute myeloid leukemia (AML)-derived KG-1 and U937 cells. Materials and Methods: We designed various assays to survey the antitumor impacts and molecular mechanisms underlying the action of BKM120 for the treatment of AML, and we performed experiments to check the effect of BKM120 in combination with idarubicin. Results: We found that PI3K inhibition diminished cell viability and metabolic activity and exerted a concentration-dependent growth-suppressive effect on the cells. Moreover, we suggested that the ability of BKM120 to induce its antiproliferative properties was mediated through the induction of p21-mediated G2/M cell-cycle arrest. Investigating the effect of inhibitor on the molecular features revealed not only that BKM120 reduced the expression of NF-κB antiapoptotic targets, but also that NF-κB suppression using bortezomib profoundly enhanced the cytotoxicity of the inhibitor, highlighting that the antileukemic effects of BKM120 are mediated, at least partly, through the modulation of the NF-κB pathway. Interestingly, we found that the single agent of BKM120 was unable to significantly alter the expression level of c-Myc; however, the capability of BKM120 to reduce the survival rate of AML cells was potentiated upon c-Myc inhibition using 10058-F4, suggestive of the plausible contribution of c-Myc in leukemic cell response to the PI3K inhibitor. Conclusion: Taken together, the results of this study reveal the efficacy of BKM120 as a therapeutic approach for AML; however, further investigations should be undertaken to determine the expediency of this inhibitor.

The Role of M2000 as an Anti-inflammatory Agent in Toll-Like Receptor 2/microRNA-155 Pathway.

BACKGROUND: M2000 is a newly designed and safe Non-Steroidal Anti-Inflammatory Drug (NSAID). The aim of this study was to assess the effects of M2000 on expression levels of Suppressor of Cytokine Signaling-1 (SOCS-1) and Src Homology-2 domain-containing inositol-5'-phosphatase 1 (SHIP1) proteins via Toll-Like Receptor (TLR) 2/microRNA-155 pathway. METHODS: HEK293 TLR2 cell line and Peripheral Blood Mononuclear Cells (PBMCs) were treated by different concentrations of M2000 in MTT assay. RNA was extracted by miRNeasy Mini kit. Then, cDNA was synthesized and the expression levels of SOCS1, SHIP1 and miRNA155 were evaluated by Quantitative Real time PCR. RESULTS: Our results showed that M2000 significantly increased the expression levels of SOCS1 and SHIP-1 in Lipopolysachride (LPS)-treated and non-treated cells. Moreover, M2000 decreased expression level of miR-155 in LPS treated PBMCs. CONCLUSION: M2000 can be used as NSAID in LPS induced inflammation and decrease inflammatory cytokines production by targeting SOCS1, SHIP1 and miR-155 in auto-immune and inflammatory diseases.

Application of nanoparticle technology in the treatment of Systemic lupus erythematous.

Systemic lupus erythematous (SLE) is a chronic heterogeneous multisystem autoimmune disease characterized by loss of tolerance to self-antigens and production of numerous autoantibodies. Current therapeutic approaches used to treat inflammatory autoimmune diseases are associated with debilitating side effects. In spite of significant advances in therapeutic options and increased understanding of the pathogenesis, novel therapeutic approaches are needed for treatment of SLE. Nanoparticle-based delivery systems that selectively deliver drugs to inflamed tissue or specific cell have the potential to improve drug delivery. This article reviews recent nanotechnology-based therapeutics strategies that are being developed for the treatment of SLE.