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Computational Biology and Chemistry Dec 2018The B-cell lymphoma-2 (Bcl-2) family proteins have been attributed to be the key regulators in programmed cell death and apoptosis with a prominent role in human cancer....
The B-cell lymphoma-2 (Bcl-2) family proteins have been attributed to be the key regulators in programmed cell death and apoptosis with a prominent role in human cancer. Understanding the fundamental principles of cell survival and death have been the main cornerstone in cancer drug discovery for identification of novel anticancer agents. In this context the Bcl-2 family of anti-and pro-apoptotic proteins provide an excellent opportunity for development of anticancer agents, as blocking the Bcl-2 or Bcl-XL functionally promotes apoptosis in tumor cells and also sensitize them to chemo- and radiotherapies. The present study reports the identification of novel Aplysin analogs as BCL-2 inhibitors from a sequential virtual screening approach using drug-like, ADMET, docking, pharmacophore filters and molecular dynamics simulation. We identified promising Aplysin analogs that have a potential to be Bcl-2 inhibitors just like the standard drug Obatoclax. One of the compound analog 11 was identified to be a promising inhibitor of Bcl-2 in the docking, pharmacophore and simulation based models.The molecular modeling information provided here can be vital in designing of the novel Bcl-2 inhibitors.
Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Computer-Aided Design; Drug Design; Humans; Hydrocarbons, Brominated; Molecular Docking Simulation; Molecular Dynamics Simulation; Neoplasms; Proto-Oncogene Proteins c-bcl-2; Sesquiterpenes
PubMed: 30469054
DOI: 10.1016/j.compbiolchem.2018.09.003 -
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 -
Journal of Cellular Physiology Apr 2019Three-dimensional (3D) culture systems such as floating spheroids (FSs) and floating tumorspheres (FTs) are widely used as tumor models of chemoresistance. FTs are...
Three-dimensional (3D) culture systems such as floating spheroids (FSs) and floating tumorspheres (FTs) are widely used as tumor models of chemoresistance. FTs are considered to be enriched in cancer stem-like cells (CS-LCs). In this study, we used cancer cell lines (lung H460, prostate LnCAP, and breast MCF-7) able to form FSs under anchorage-independent conditions and compared with cell lines (prostate PC3 and breast MDA-MB-231) that cannot form FSs under similar conditions. Independent of their ability to form FTs all cell lines growing under anchorage-independent conditions become highly resistant to obatoclax, colchicine, and hydroxyurea. We used anti-E-cadherin antibody (that blocked the formation of FSs) and demonstrated that floating LnCAP cells showed similar chemoresistance regardless of the formation of spheroids. Our results demonstrate that the development of chemoresistance is not because of the formation of a complex 3D structure and/or enrichment of CS-LCs but is likely the result of cell detachment per se and their ability to survive under anchorage-independent conditions. We propose that FSs and FTs could be useful models to study chemoresistance of cancer cells associated with cell detachment (e.g., circulating tumor cells) but they may not be representative of other types of chemoresistance that arise in vivo in attached cells.
Topics: Antibodies; Antigens, CD; Antineoplastic Agents; Cadherins; Cell Adhesion; Cell Culture Techniques; Cell Survival; Colchicine; Culture Media, Serum-Free; Drug Resistance, Neoplasm; Female; Humans; Hydroxyurea; Indoles; MCF-7 Cells; Male; Neoplasms; PC-3 Cells; Phenotype; Pyrroles; Spheroids, Cellular
PubMed: 30191978
DOI: 10.1002/jcp.27239 -
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 -
Molecular Medicine Reports Jul 2018The present study aimed to investigate the effects of obatoclax (OBX) combined with gemcitabine (GEM) treatment on the proliferation, migration, invasion and...
The present study aimed to investigate the effects of obatoclax (OBX) combined with gemcitabine (GEM) treatment on the proliferation, migration, invasion and epithelial‑mesenchymal transition (EMT) related proteins of pancreatic cancer cell line BxPC‑3 under hypoxic conditions. Protein expression levels of hypoxia‑inducible factor 1α (HIF‑1α) in BxPC‑3 pancreatic cancer cells under normoxic and hypoxic conditions were detected by western blotting. Cells were divided into four groups: Normoxia group, hypoxia group, OBX group and OBX + GEM group. The proliferation activity of BxPC‑3 cells was detected by Cell Counting kit‑8. The migratory and invasive abilities of BxPC‑3 cells were detected by the scratch test and Matrigel assay, respectively. The protein expression levels of vimentin, E‑cadherin and p53 in BxPC‑3 cells were also detected by western blotting. HIF‑1α expression under hypoxic conditions was significantly increased compared with expression under normoxic conditions. Under hypoxic conditions, OBX treatment reduced cell activity, decreased cell migration and invasion, promoted the expression of E‑cadherin and p53. In the OBX + GEM group, BxPC‑3 cell activity decreased significantly, cell migration and invasion decreased significantly, the expression of vimentin was significantly reduced and the expression of E‑cadherin and p53 further increased. In conclusion, the present results demonstrated that under hypoxic conditions, OBX combined with a small dose of GEM may be able to inhibit the growth, migration and invasion of pancreatic cancer cells, possibly via inhibition of EMT process. These results may provide a promising strategy for pancreatic cancer therapy.
Topics: Antineoplastic Combined Chemotherapy Protocols; Cadherins; Cell Hypoxia; Cell Line, Tumor; Cell Movement; Deoxycytidine; Epithelial-Mesenchymal Transition; Humans; Indoles; Neoplasm Invasiveness; Pancreatic Neoplasms; Pyrroles; Tumor Suppressor Protein p53; Gemcitabine
PubMed: 29749486
DOI: 10.3892/mmr.2018.8932 -
Chembiochem : a European Journal of... Jul 2018Prodiginines are a group of naturally occurring pyrrole alkaloids produced by various microorganisms and known for their broad biological activities. The production of...
Prodiginines are a group of naturally occurring pyrrole alkaloids produced by various microorganisms and known for their broad biological activities. The production of nature-inspired cyclic prodiginines was enabled by combining organic synthesis with a mutasynthesis approach based on the GRAS (generally recognized as safe) certified host strain Pseudomonas putida KT2440. The newly prepared prodiginines exerted antimicrobial effects against relevant alternative biotechnological microbial hosts whereas P. putida itself exhibited remarkable tolerance against all tested prodiginines, thus corroborating the bacterium's exceptional suitability as a mutasynthesis host for the production of these cytotoxic secondary metabolites. Moreover, the produced cyclic prodiginines proved to be autophagy modulators in human breast cancer cells. One promising cyclic prodiginine derivative stood out, being twice as potent as prodigiosin, the most prominent member of the prodiginine family, and its synthetic derivative obatoclax mesylate.
PubMed: 29719131
DOI: 10.1002/cbic.201800154 -
Apoptosis : An International Journal on... Jan 2018Annona muricata Linn or usually identified as soursop is a potential anticancer plant that has been widely reported to contain valuable chemopreventive agents known as...
Annona muricata Linn or usually identified as soursop is a potential anticancer plant that has been widely reported to contain valuable chemopreventive agents known as annonaceous acetogenins. The antiproliferative and anticancer activities of this tropical and subtropical plant have been demonstrated in cell culture and animal studies. A. muricata L. exerts inhibition against numerous types of cancer cells, involving multiple mechanism of actions such as apoptosis, a programmed cell death that are mainly regulated by Bcl-2 family of proteins. Nonetheless, the binding mode and the molecular interactions of the plant's bioactive constituents have not yet been unveiled for most of these mechanisms. In the current study, we aim to elucidate the binding interaction of ten bioactive phytochemicals of A. muricata L. to three Bcl-2 family of antiapoptotic proteins viz. Bcl-2, Bcl-w and Mcl-1 using an in silico molecular docking analysis software, Autodock 4.2. The stability of the complex with highest affinity was evaluated using MD simulation. We compared the docking analysis of these substances with pre-clinical Bcl-2 inhibitor namely obatoclax. The study identified the potential chemopreventive agent among the bioactive compounds. We also characterized the important interacting residues of protein targets which involve in the binding interaction. Results displayed that anonaine, a benzylisoquinoline alkaloid, showed a high affinity towards the Bcl-2, thus indicating that this compound is a potent inhibitor of the Bcl-2 antiapoptotic family of proteins.
Topics: Annona; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Regulatory Proteins; Aporphines; Binding Sites; Dioxoles; Gene Expression; Humans; Hydrophobic and Hydrophilic Interactions; Indoles; Molecular Docking Simulation; Myeloid Cell Leukemia Sequence 1 Protein; Plant Extracts; Plant Leaves; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Structural Homology, Protein
PubMed: 29204721
DOI: 10.1007/s10495-017-1434-7