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Oncogene Mar 2019The poor outcomes in infant acute lymphoblastic leukemia (ALL) necessitate new treatments. Here we discover that EIF4E protein is elevated in most cases of infant ALL...
The poor outcomes in infant acute lymphoblastic leukemia (ALL) necessitate new treatments. Here we discover that EIF4E protein is elevated in most cases of infant ALL and test EIF4E targeting by the repurposed antiviral agent ribavirin, which has anticancer properties through EIF4E inhibition, as a potential treatment. We find that ribavirin treatment of actively dividing infant ALL cells on bone marrow stromal cells (BMSCs) at clinically achievable concentrations causes robust proliferation inhibition in proportion with EIF4E expression. Further, we find that ribavirin treatment of KMT2A-rearranged (KMT2A-R) infant ALL cells and the KMT2A-AFF1 cell line RS4:11 inhibits EIF4E, leading to decreases in oncogenic EIF4E-regulated cell growth and survival proteins. In ribavirin-sensitive KMT2A-R infant ALL cells and RS4:11 cells, EIF4E-regulated proteins with reduced levels of expression following ribavirin treatment include MYC, MCL1, NBN, BCL2 and BIRC5. Ribavirin-treated RS4:11 cells exhibit impaired EIF4E-dependent nuclear to cytoplasmic export and/or translation of the corresponding mRNAs, as well as reduced phosphorylation of the p-AKT1, p-EIF4EBP1, p-RPS6 and p-EIF4E signaling proteins. This leads to an S-phase cell cycle arrest in RS4:11 cells corresponding to the decreased proliferation. Ribavirin causes nuclear EIF4E to re-localize to the cytoplasm in KMT2A-AFF1 infant ALL and RS4:11 cells, providing further evidence for EIF4E inhibition. Ribavirin slows increases in peripheral blasts in KMT2A-R infant ALL xenograft-bearing mice. Ribavirin cooperates with chemotherapy, particularly L-asparaginase, in reducing live KMT2A-AFF1 infant ALL cells in BMSC co-cultures. This work establishes that EIF4E is broadly elevated across infant ALL and that clinically relevant ribavirin exposures have preclinical activity and effectively inhibit EIF4E in KMT2A-R cases, suggesting promise in EIF4E targeting using ribavirin as a means of treatment.
Topics: Cell Line, Tumor; Child, Preschool; Drug Resistance, Neoplasm; Eukaryotic Initiation Factor-4E; Gene Expression Profiling; Gene Expression Regulation, Leukemic; Humans; Indoles; Infant; Microarray Analysis; Molecular Targeted Therapy; Multigene Family; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Protein Biosynthesis; Pyrroles; Ribavirin; Signal Transduction
PubMed: 30478448
DOI: 10.1038/s41388-018-0567-7 -
Antioxidants (Basel, Switzerland) Oct 2018Pulmonary arterial hypertension (PAH) is a fatal disease without satisfactory therapeutic options. By the time patients are diagnosed with this disease, the remodeling...
Pulmonary arterial hypertension (PAH) is a fatal disease without satisfactory therapeutic options. By the time patients are diagnosed with this disease, the remodeling of pulmonary arteries has already developed due to the abnormal growth of pulmonary vascular cells. Therefore, agents that reduce excess pulmonary vascular cells have therapeutic potential. Bcl-2 is known to function in an antioxidant pathway to prevent apoptosis. The present study examined the effects of inhibitors of the anti-apoptotic proteins Bcl-2 and Bcl-x. ABT-263 (Navitoclax), ABT-199 (Venetoclax), ABT-737, and Obatoclax, which all promoted the death of cultured human pulmonary artery smooth muscle cells. Further examinations using ABT-263 showed that Bcl-2/Bcl-x inhibition indeed promoted apoptotic programmed cell death. ABT-263-induced cell death was inhibited by antioxidants. ABT-263 also promoted autophagy; however, the inhibition of autophagy did not suppress ABT-263-induced cell death. This is in contrast to other previously studied drugs, including anthracyclines and proteasome inhibitors, which were found to mediate autophagy to induce cell death. The administration of ABT-263 to rats with PAH in vivo resulted in the reversal of pulmonary vascular remodeling. Thus, promoting apoptosis by inhibiting anti-apoptotic Bcl-2 and Bcl-x effectively kills pulmonary vascular smooth muscle cells and reverses pulmonary vascular remodeling.
PubMed: 30373097
DOI: 10.3390/antiox7110150 -
BMC Cancer Oct 2018Lapatinib has clinical efficacy in the treatment of trastuzumab-refractory HER2-positive breast cancer. However, a significant proportion of patients develop progressive...
BACKGROUND
Lapatinib has clinical efficacy in the treatment of trastuzumab-refractory HER2-positive breast cancer. However, a significant proportion of patients develop progressive disease due to acquired resistance to the drug. Induction of apoptotic cell death is a key mechanism of action of lapatinib in HER2-positive breast cancer cells.
METHODS
We examined alterations in regulation of the intrinsic and extrinsic apoptosis pathways in cell line models of acquired lapatinib resistance both in vitro and in patient samples from the NCT01485926 clinical trial, and investigated potential strategies to exploit alterations in apoptosis signalling to overcome lapatinib resistance in HER2-positive breast cancer.
RESULTS
In this study, we examined two cell lines models of acquired lapatinib resistance (SKBR3-L and HCC1954-L) and showed that lapatinib does not induce apoptosis in these cells. We identified alterations in members of the BCL-2 family of proteins, in particular MCL-1 and BAX, which may play a role in resistance to lapatinib. We tested the therapeutic inhibitor obatoclax, which targets MCL-1. Both SKBR3-L and HCC1954-L cells showed greater sensitivity to obatoclax-induced apoptosis than parental cells. Interestingly, we also found that the development of acquired resistance to lapatinib resulted in acquired sensitivity to TRAIL in SKBR3-L cells. Sensitivity to TRAIL in the SKBR3-L cells was associated with reduced phosphorylation of AKT, increased expression of FOXO3a and decreased expression of c-FLIP. In SKBR3-L cells, TRAIL treatment caused activation of caspase 8, caspase 9 and caspase 3/7. In a second resistant model, HCC1954-L cells, p-AKT levels were not decreased and these cells did not show enhanced sensitivity to TRAIL. Furthermore, combining obatoclax with TRAIL improved response in SKBR3-L cells but not in HCC1954-L cells.
CONCLUSIONS
Our findings highlight the possibility of targeting altered apoptotic signalling to overcome acquired lapatinib resistance, and identify potential novel treatment strategies, with potential biomarkers, for HER2-positive breast cancer that is resistant to HER2 targeted therapies.
Topics: Antineoplastic Agents; Apoptosis; Breast Neoplasms; CASP8 and FADD-Like Apoptosis Regulating Protein; Cell Line, Tumor; Drug Resistance, Neoplasm; Female; Forkhead Box Protein O3; Gene Expression; Genes, erbB-2; Humans; Lapatinib; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; TNF-Related Apoptosis-Inducing Ligand
PubMed: 30305055
DOI: 10.1186/s12885-018-4852-1 -
Cancers Sep 2018Ion homeostasis is extremely important for the survival of both normal as well as neoplastic cells. The altered ion homeostasis found in cancer cells prompted the... (Review)
Review
Ion homeostasis is extremely important for the survival of both normal as well as neoplastic cells. The altered ion homeostasis found in cancer cells prompted the investigation of several ionophores as potential anticancer agents. Few ionophores, such as Salinomycin, Nigericin and Obatoclax, have demonstrated potent anticancer activities against cancer stem-like cells that are considered highly resistant to chemotherapy and responsible for tumor relapse. The preclinical success of these compounds in in vitro and in vivo models have not been translated into clinical trials. At present, phase I/II clinical trials demonstrated limited benefit of Obatoclax alone or in combination with other anticancer drugs. However, future development in targeted drug delivery may be useful to improve the efficacy of these compounds. Alternatively, these compounds may be used as leading molecules for the development of less toxic derivatives.
PubMed: 30262730
DOI: 10.3390/cancers10100360 -
Frontiers in Cellular and Infection... 2018Neglected tropical diseases, especially those caused by parasites, are significantly underserved by current drug development efforts, mostly due to the high costs and...
Neglected tropical diseases, especially those caused by parasites, are significantly underserved by current drug development efforts, mostly due to the high costs and low economic returns. One method for lowering the costs of drug discovery and development for these diseases is to repurpose drugs developed for other indications. Here, we present the results of a screen of five repurposed drug libraries to identify potential new lead compounds to treat amebiasis, a disease that affects tens of millions of people and causes ~100,000 deaths annually. , the causative agent of amebiasis, has two major life cycle stages, the trophozoite and the cyst. The current primary treatment for amebiasis, nitroimidazole compounds, do not eliminate parasites from the colonic lumen, necessitating a multi-drug treatment regimen. We aimed to address this problem by screening against both life stages, with the aim of identifying a single drug that targets both. We successfully identified eleven compounds with activity against both cysts and trophozoites, as well as multiple compounds that killed trophozoites with improved efficacy over existing drugs. Two lead compounds (anisomycin and prodigiosin) were further characterized for activity against metronidazole (MNZ) resistant parasites and mature cysts. Anisomycin and prodigiosin were both able to kill MNZ resistant parasites while prodigiosin and its analog obatoclax were active against mature cysts. This work confirms the feasibility of identifying drugs that target both trophozoites and cysts, and is an important step toward developing improved treatment regimens for infection.
Topics: Anisomycin; Antiprotozoal Agents; Cell Survival; Drug Evaluation, Preclinical; Drug Repositioning; Drug Resistance; Entamoeba; High-Throughput Screening Assays; Life Cycle Stages; Metronidazole; Prodigiosin; Spores, Protozoan; Trophozoites
PubMed: 30175074
DOI: 10.3389/fcimb.2018.00276 -
Oncotarget Jun 2018The activated JAK2-V617F mutant is very frequently found in myeloproliferative neoplasms (MPNs), and its inhibitor ruxolitinib has been in clinical use, albeit with...
Mechanisms for mTORC1 activation and synergistic induction of apoptosis by ruxolitinib and BH3 mimetics or autophagy inhibitors in JAK2-V617F-expressing leukemic cells including newly established PVTL-2.
The activated JAK2-V617F mutant is very frequently found in myeloproliferative neoplasms (MPNs), and its inhibitor ruxolitinib has been in clinical use, albeit with limited efficacies. Here, we examine the signaling mechanisms from JAK2-V617F and responses to ruxolitinib in JAK2-V617F-positive leukemic cell lines, including PVTL-2, newly established from a patient with post-MPN secondary acute myeloid leukemia, and the widely used model cell line HEL. We have found that ruxolitinib downregulated the mTORC1/S6K/4EBP1 pathway at least partly through inhibition of the STAT5/Pim-2 pathway with concomitant downregulation of c-Myc, MCL-1, and BCL-xL as well as induction of autophagy in these cells. Ruxolitinib very efficiently inhibited proliferation but only modestly induced apoptosis. However, inhibition of BCL-xL/BCL-2 by the BH3 mimetics ABT-737 and navitoclax or BCL-xL by A-1331852 induced caspase-dependent apoptosis involving activation of Bak and Bax synergistically with ruxolitinib in HEL cells. On the other hand, the putative pan-BH3 mimetic obatoclax as well as chloroquine and bafilomycin A1 inhibited autophagy at its late stage and induced apoptosis in PVTL-2 cells synergistically with ruxolitinib. The present study suggests that autophagy as well as the anti-apoptotic BCL-2 family members, regulated at least partly by the mTORC1 pathway downstream of STAT5/Pim-2, protects JAK2-V617F-positive leukemic cells from ruxolitinib-induced apoptosis depending on cell types and may contribute to development of new strategies against JAK2-V617F-positive neoplasms.
PubMed: 29928488
DOI: 10.18632/oncotarget.25515 -
Oncotarget Sep 2017Acute lymphoblastic leukemia (ALL) is characterized by leukemic expansion of lymphoid blasts in hematopoietic tissues. Despite improved therapy only a subset of patients...
Acute lymphoblastic leukemia (ALL) is characterized by leukemic expansion of lymphoid blasts in hematopoietic tissues. Despite improved therapy only a subset of patients can be cured. Therefore, current research is focusing on new drug-targets. Members of the BCL-2 family and components of the PI3-kinase/mTOR pathway are critically involved in the regulation of growth and survival of ALL cells. We examined the effects of the pan-BCL-2 blocker obatoclax and the PI3-kinase/mTOR-inhibitor BEZ235 on growth and survival of ALL cells. In H-thymidine uptake experiments, both drugs suppressed the proliferation of leukemic cells in all patients with Philadelphia chromosome-positive (Ph) ALL and Ph ALL (obatoclax IC: 0.01-5 μM; BEZ235, IC: 0.01-1 μM). Both drugs were also found to produce growth-inhibitory effects in all Ph and all Ph cell lines tested. Moreover, obatoclax and BEZ235 induced apoptosis in ALL cells. In drug-combination experiments, obatoclax and BEZ235 exerted synergistic growth-inhibitory effects on ALL cells. Finally, we confirmed that ALL cells, including CD34/CD38 stem cells and all cell lines express transcripts for PI3-kinase, mTOR, BCL-2, MCL-1, and BCL-xL. Taken together, this data shows that combined targeting of the PI3-kinase/mTOR-pathway and BCL-2 family-members is a potent approach to counteract growth and survival of ALL cells.
PubMed: 28978065
DOI: 10.18632/oncotarget.18810 -
Oncotarget Sep 2017We have previously reported overexpression of antiapoptotic MCL-1 protein in human oral cancers and its association with therapy resistance and poor prognosis, implying...
We have previously reported overexpression of antiapoptotic MCL-1 protein in human oral cancers and its association with therapy resistance and poor prognosis, implying it to be a potential therapeutic target. Hence, we investigated the efficacy and mechanism of action of Obatoclax, a BH3 mimetic pan BCL-2 inhibitor in human oral cancer cell lines. All cell lines exhibited high sensitivity to Obatoclax with complete clonogenic inhibition at 200-400 nM concentration which correlated with their MCL-1 expression. Mechanistic insights revealed that Obatoclax induced a caspase-independent cell death primarily by induction of a defective autophagy. Suppression of autophagy by ATG5 downregulation significantly blocked Obatoclax-induced cell death. Further, Obatoclax induced interaction of p62 with key components of the necrosome RIP1K and RIP3K. Necrostatin-1 mediated inhibition of RIP1K significantly protected the cells from Obatoclax induced cell death. Moreover, Obatoclax caused extensive mitochondrial stress leading to their dysfunction. Interestingly, MCL-1 downregulation alone caused mitochondrial stress, highlighting its importance for mitochondrial homeostasis. We also demonstrated efficacy of Obatoclax against oral cancer xenografts and its synergism with ionizing radiation . Our studies thus suggest that Obatoclax induces autophagy-dependent necroptosis in oral cancer cells and holds a great promise in the improved management of oral cancer patients.
PubMed: 28947954
DOI: 10.18632/oncotarget.11085 -
International Journal of Molecular... Sep 2017Autophagy is an essential catabolic program that forms part of the stress response and enables cells to break down their own intracellular components within lysosomes... (Review)
Review
Autophagy is an essential catabolic program that forms part of the stress response and enables cells to break down their own intracellular components within lysosomes for recycling. Accumulating evidence suggests that autophagy plays vital roles in determining pathological outcomes of immune responses and tumorigenesis. Autophagy regulates innate and adaptive immunity affecting the pathologies of infectious, inflammatory, and autoimmune diseases. In cancer, autophagy appears to play distinct roles depending on the context of the malignancy by either promoting or suppressing key determinants of cancer cell survival. This review covers recent developments in the understanding of autophagy and discusses potential therapeutic interventions that may alter the outcomes of certain diseases.
Topics: Adaptive Immunity; Animals; Autoimmune Diseases; Autophagy; Benzylisoquinolines; Cholecalciferol; Humans; Immune System Diseases; Immunity, Innate; Indoles; Infections; Isoquinolines; Lysosomes; Maprotiline; Metformin; Neoplasms; Phenols; Pyrroles; Resveratrol; Sirolimus; Spermidine; Stilbenes; Tetrahydroisoquinolines; Trehalose
PubMed: 28895911
DOI: 10.3390/ijms18091959 -
Electrophoresis Aug 2017Inherent electrical properties of cells can be beneficial to characterize different cell lines and their response to experimental drugs. This paper presents a novel...
Inherent electrical properties of cells can be beneficial to characterize different cell lines and their response to experimental drugs. This paper presents a novel method to characterize the response of breast cancer cells to drug stimuli through use of off-chip passivated-electrode insulator-based dielectrophoresis (OπDEP) and the application of AC electric fields. This work is the first to demonstrate the ability of OπDEP to differentiate between two closely related breast cancer cell lines, LCC1 and LCC9 while assessing their drug sensitivity to an experimental anti-cancer agent, Obatoclax. Although both cell lines are derivatives of estrogen-responsive MCF-7 breast cancer cells, growth of LCC1 is estrogen independent and anti-estrogen responsive, while LCC9 is both estrogen-independent and anti-estrogen resistant. Under the same operating conditions, LCC1 and LCC9 had different DEP profiles. LCC1 cells had a trapping onset (crossover) frequency of 700 kHz and trapping efficiencies between 30-40%, while LCC9 cells had a lower crossover frequency (100 kHz) and showed higher trapping efficiencies of 40-60%. When exposed to the Obatoclax, both cell lines exhibited dose-dependent shifts in DEP crossover frequency and trapping efficiency. Here, DEP results supplemented with cell morphology and proliferation assays help us to understand the response of these breast cancer cells to Obatoclax.
Topics: Antineoplastic Agents; Breast Neoplasms; Cell Proliferation; Cell Size; Drug Resistance, Neoplasm; Electrodes; Electrophoresis; Estrogen Antagonists; Female; Humans; Indoles; MCF-7 Cells; Microfluidic Analytical Techniques; Pyrroles
PubMed: 28608427
DOI: 10.1002/elps.201600447