Ponatinib and STAT5 Inhibitor Pimozide Combined Synergistic Treatment Applications Potentially Overcome Drug Resistance via Regulating the Cytokine Expressional Network in Chronic Myeloid Leukemia Cells.

Chronic myeloid leukemia (CML) is a clonal myeloproliferative hematological disease characterized by the chimeric breakpoint-cluster region/Abelson kinase1 (BCR::ABL1) oncoprotein; playing a pivotal role in CML molecular pathology, diagnosis, treatment, and possible resistance arising from the success and tolerance of tyrosine kinase inhibitor (TKI)-based therapy. The transcription factor STAT5 constitutive signaling, which is influenced by the cytokine signaling network, triggers BCR::ABL1-based CML pathogenesis and is also relevant to acquired TKI resistance. The unsuccessful therapeutic approaches targeting BCR::ABL1, in particular third-line therapy with ponatinib, still need to be further developed with alternative combination strategies to overcome drug resistance. As treatment with the STAT5 inhibitor pimozide in combination with ponatinib resulted in an efficient and synergistic therapeutic approach in TKI-resistant CML cells, this study focused on identifying the underlying amplification of ponatinib response mechanisms by determining different cytokine expression profiles in parental and ponatinib-resistant CML cells, in vitro. The results showed that expression of interleukin (IL) 1B, IL9, and IL12A-B was increased by 2-fold, while IL18 was downregulated by 2-fold in the ponatinib-resistant cells compared to sensitive ones. Importantly, ponatinib treatment upregulated the expression of 21 of the 23 interferon and IL genes in the ponatinib-resistant cells, while treatment with pimozide or a combination dose resulted in a reduction in the expression of 19 different cytokine genes, such as for example, inflammatory cytokines, IL1A-B and IL6 or cytokine genes associated with supporting tumor progression, leukemia stem cell growth or poor survival, such as IL3, IL8, IL9, IL10, IL12, or IL15. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis results showed that the genes were mainly enriched in the regulation of receptor signaling through the Janus kinase/signal transducer and activator of transcription pathway, cytokine-cytokine receptor interaction, and hematopoietic cell lineage. Protein-protein interaction analysis showed that IL2, IL6, IL15, IFNG, and others appeared in the top lists of pathways, indicating their high centrality and importance in the network. Therefore, pimozide could be a promising agent to support TKI therapies in ponatinib resistance. This research would help to clarify the role of cytokines in ponatinib resistance and advance the development of new therapeutics to utilize the STAT5 inhibitor pimozide in combination with TKIs.

STAT5 inhibitor Pimozide as a probable therapeutic option in overcoming Ponatinib resistance in K562 leukemic cells.

Signal Transducer and Activator of Transcription 5 (STAT5) is a transcription factor that plays a key role in neoplasia, triggered by the fusion oncogene BCR-ABL1; it is not only an essential protein for the pathogenesis of chronic myeloid leukemia (CML), but also its overexpression is associated with drug resistance developed toward various generations of Tyrosine Kinase Inhibitors (TKIs); these are still accepted as gold standard therapeutics for the treatment of CML. In this study, it was investigated whether suppression of STAT5 via a "STAT5 inhibitor" Pimozide resulted in any regain of chemosensitivity to third-generation TKI Ponatinib. Accordingly, the experimental work was designed on both parental CML cell line K562WT and its 1 nM Ponatinib-resistant counterpart, indicated as K562-Pon1. Based on the experimental results, Pimozide was more effective in resistant cells compared to wild-type cells for inducing apoptosis and block cell arrest. Combination therapy of Pimozide and Ponatinib demonstrated that STAT5 was a significant protein for regaining chemosensitivity to Ponatinib when its expression was suppressed both at mRNA and protein level. In conclusion, we consider that STAT5 inhibitor Pimozide can be a good alternative or combination therapy with TKIs for patients suffering from chemotherapeutic drug resistance. Communicated by Ramaswamy H. Sarma.

Investigating the potential therapeutic role of targeting STAT3 for overcoming drug resistance by regulating energy metabolism in chronic myeloid leukemia cells.

Objectives: STATs are one of the initial targets of emerging anti-cancer agents due to their regulatory roles in survival, apoptosis, drug response, and cellular metabolism in CML. Aberrant STAT3 activity promotes malignancy, and acts as a metabolic switcher in cancer cell metabolism, contributing to resistance to TKI nilotinib. To investigate the possible therapeutic effects of targeting STAT3 to overcome nilotinib resistance by evaluating various cellular responses in both sensitive and nilotinib resistant CML cells and to test the hypothesis that energy metabolism modulation could be a mechanism for re-sensitization to nilotinib in resistant cells. Materials and Methods: By using RNAi-mediated STAT3 gene silencing, cell viability and proliferation assays, apoptotic analysis, expressional regulations of STAT mRNA transcripts, STAT3 total, pTyr705, pSer727 protein expression levels, and metabolic activity as energy metabolism was determined in CML model K562 cells, in vitro. Results: Targeting STAT3 sensitized both parental and especially nilotinib resistant cells by decreasing leukemic cell survival; inducing leukemic cell apoptosis, and decreasing STAT3 mRNA and protein expression levels. Besides, cell energy phenotype was modulated by switching energy metabolism from aerobic glycolysis to mitochondrial respiration in resistant cells. RNAi-mediated STAT3 silencing accelerated the sensitization of leukemia cells to nilotinib treatment, and STAT3-dependent energy metabolism regulation could be another underlying mechanism for regaining nilotinib response. Conclusion: Targeting STAT3 is an efficient strategy for improving the development of novel CML therapeutics for regaining nilotinib response, and re-sensitization of resistant cells could be mediated by induced apoptosis and regulation in energy metabolism.

Investigating the Effects of a Synthetic Cannabinoid on the Pathogenesis of Leukemia and Leukemic Stem Cells: A New Therapeutic Approach.

The popularity and usage of synthetic cannabinoids (SCs) are increasing due to their easy accessibility and psychoactive effects worldwide. Studies on cannabinoids on leukemic stem cells (LSC) and hematopoietic stem cells (HSCs), which are the precursors of leukemia cells, generally depend on the natural cannabinoid delta-9-THC. As there is only a limited number of studies focusing on the results of SC applications, the reflections upon LSCs have to be clarified. In this study, biological responses and antileukemic effects of JWH-018-one of the first produced and widely used SCs-were evaluated upon leukemia cells. Whether JWH-018 exhibited a preventive effect on both leukemic and HSCs was evaluated by presenting a therapeutic approach for the first time in the literature. Cells were analyzed in case of cell proliferation, apoptosis, and transcriptional expression profiling of some significant JAK/STAT and AKT/mTOR pathways, apoptotic, cell cycle regulation, and epigenetic chromatin remodeling-related genes following JWH-018 treatment. In conclusion, however, further studies are still needed upon both HSCs and LSCs to illuminate the effects of SCs on leukemogenesis on chronic myeloid leukemia (CML) more clearly; we consider that the JWH-018 can provide a therapeutic effect on the pathogenesis of leukemia and particularly upon LSCs and SCs might have therapeutic potential in addition to current therapy.

Targeting UPR signaling pathway by dasatinib as a promising therapeutic approach in chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is a myeloproliferative disease that mediated by BCR/ABL oncogenic signaling. CML can be targeted with the imatinib, dasatinib, and nilotinib TKI inhibitors, the latter two of them have been approved for imatinib-resistant or -intolerant CML patients. The TKIs resistance occurs by different molecular mechanisms, including overexpression of BCR-ABL, mutations in the TKI binding site of BCR/ABL, and ER-stress. Unfolded protein responses (UPR) is a cytoprotective mechanism which is activated by ER-stress. The IRE1, PERK, and ATF6 are three main arms of the UPR mechanism and are activated by a common mechanism involving the dissociation of the ER-chaperone BiP/GP78. There is a correlation between ER-stress, CML progression, and response to TKI treatment. In the present study, we aimed to determine alterations of the expression levels of genes related to UPR pathway signaling after treatment with dasatinib in K562 chronic myeloid leukemia cell line by quantitative RT-PCR relatively. The array-data revealed that treatment with dasatinib significantly decreased the UPR mechanism-related genes (including HSPA1B, HSPA2, HSPA4L, ATF6, ATF6B, CEBPB, PERK, TRIB3, DNAJB, ERN1, and UHRF1) in K562 cells. In conclusion, the results showed that dasatinib regulates the UPR mechanism that plays a significant role in cancer progression and therapy resistance in CML. Thus, dasatinib-induced dysfunction of the UPR mechanism may promise encouraging therapy for CML.

TET2, ASXL1, IDH1, and IDH2 Single Nucleotide Polymorphisms in Turkish Patients with Chronic Myeloproliferative Neoplasms.

We aimed to determine the genotype distribution, allele frequency, and prognostic impact of IDH1/2, TET2, and ASXL1 single nucleotide polymorphisms (SNPs) in myeloproliferative neoplasms (MPNs). TET2 (rs763480), ASXL1 (rs2208131), and IDH1 (rs11554137) variant homozygous genotype frequencies were found at rates of 1.5%, 9.2%, and 2.3%, respectively. No IDH2 SNP was identified. IDH1 and TET2 frequencies were 5% in essential thrombocythemia (ET) and 1.7% in ET and 5% in primary myelofibrosis (PMF), respectively. ASXL1 frequencies were 8.3%-10% in MPN subgroups. The TET2 mutant allele T and ASXL1 mutant allele G had the highest frequencies with 0.272 in the PMF and 0.322 in the polycythemia vera (PV) group, respectively. There was no impact of the SNPs on prognosis. IDH1 frequency in MPNs was found similar to the literature. ASXL1 frequencies were similar between ET, PV, and PMF patients. The ASXL1 and TET2 allele frequencies of the Turkish population are similar to those of the European population. The role of SNPs in MPNs might be further evaluated in larger multicenter studies.

Effects of flavopiridol on critical regulation pathways of CD133high/CD44high lung cancer stem cells.

BACKGROUND: Flavopiridol a semisynthetic flavone that inhibits cyclin-dependent kinases (CDKs) and has growth-inhibitory activity and induces a blockade of cell-cycle progression at G1-phase and apoptosis in numerous human tumor cell lines and is currently under investigation in phase II clinical trials. Cancer stem cells (CSCs) are comprised of subpopulation of cells in tumors that have been proposed to be responsible for recurrence and resistance to chemotherapy. The aim of the present study was to investigate the effects of flavopiridol in cancer stem cell cytoskeleton, cell adhesion, and epithelial to mesenchymal transition in CSCs. METHODS: The cells were treated with flavopiridol to determine the inhibitory effect. Cell viability and proliferation were determined by using the WST-1 assay. Caspase activity and immunofluorescence analyses were performed for the evaluation of apoptosis, cell cytoskeleton, and epithelial-mesenchymal transition (EMT) markers. The effects of flavopiridol on the cell cycle were also evaluated. Flow cytometric analysis was used to detect the percentages of CSCs subpopulation. We analyzed the gene expression patterns to predict cell cycle and cell cytoskeleton in CSCs by RT-PCR. RESULTS: Flavopiridol-induced cytotoxicity and apoptosis at the IC50 dose, resulting in a significant increase expression of caspases activity. Cell cycle analyses revealed that flavopiridol induces G1 phase cell cycle arrest. Flavopiridol significantly decreased the mRNA expressions of the genes that regulate the cell cytoskeleton and cell cycle components and cell motility in CSCs. CONCLUSION: Our results suggest that Flavopiridol has activity against lung CSCs and may be effective chemotherapeutic molecule for lung cancer treatment.

miR-15a enhances the anticancer effects of cisplatin in the resistant non-small cell lung cancer cells.

Platinum-based chemotherapies have long been used as a standard treatment in non-small cell lung cancer. However, cisplatin resistance is a major problem that restricts the use of cisplatin. Deregulated cell death mechanisms including apoptosis and autophagy could be responsible for the development of cisplatin resistance and miRNAs are the key regulators of these mechanisms. We aimed to analyse the effects of selected miRNAs in the development of cisplatin resistance and found that hsa-miR-15a-3p was one of the most significantly downregulated miRNAs conferring resistance to cisplatin in Calu1 epidermoid lung carcinoma cells. Only hsa-miR-15a-3p mimic transfection did not affect cell proliferation or cell death, though decreased cell viability was found when combined with cisplatin. We found that induced expression of hsa-miR-15a-3p via mimic transfection sensitised cisplatin-resistant cells to apoptosis and autophagy. Our results demonstrated that the apoptosis- and autophagy-inducing effects of hsa-miR-15a-3p might be due to suppression of BCL2, which exhibits a major connection with cell death mechanisms. This study provides new insights into the mechanism of cisplatin resistance due to silencing of the tumour suppressor hsa-miR-15a-3p and its possible contribution to apoptosis, autophagy and cisplatin resistance, which are the devil's triangle in determining cancer cell fate.

Capsaicin induced apoptosis and gene expression dysregulation of human acute lymphoblastic leukemia CCRF-CEM cells.

PURPOSE: Capsaicin, an ingredient of red chili pepper, has possible tumorigenicity/genotoxicity properties. We aimed to determine the effects of capsaicin on the proliferation and gene expression profiles of acute lymphoblastic leukemia (ALL) CCRF-CEM cell line. METHODS: Cell viability and IC50 dose was determined by WST cytotoxicity assay. qRT-PCR, immunohistochemical staining and western blot methods were used to determine target genes' expression levels. Apoptosis was evaluated by measuring the caspase-3 activity. RESULTS: Capsaicin inhibited the proliferation of CCRFCEM cells in a dose-dependent manner. Increased mRNA expressions of caspase gene family members, activated caspase-3 and decreased mRNA and protein expression of BCL-2 gene indicated apoptotic response to capsaicin. Moreover capsaicin treatment suppressed significantly the expression of the key cell signaling pathways of KRAS, AKT, GAB2, PTPN11, BRAF, INPP5D, MAPK7. CONCLUSION: Capsaicin induces apoptosis in CCRF-CEM cells and this response is associated with downregulation of cell signaling pathways.

STAT pathway in the regulation of zoledronic acid-induced apoptosis in chronic myeloid leukemia cells.

In this study, we aimed to evaluate the cytotoxic and apoptotic effects of zoledronic acid on K562 chronic myeloid leukemia (CML) cells and to examine the roles of STAT genes on zoledronic acid-induced apoptosis. The results showed that zoledronic acid decreased proliferation, and induced apoptosis in K562 cells in a dose- and time-dependent manner. mRNA and protein levels of STAT3, -5A and -5B genes were significantly reduced in zoledronic acid-treated K562 cells. These data indicated that STAT inhibition by zoledronic acid may be therapeutic in CML patients following the confirmation with clinical studies.