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Cancer Letters Feb 2018Cisplatin resistance frequently occurs in esophageal squamous cell carcinoma (ESCC). The underlying mechanism for cisplatin resistance in ESCC remains largely obscure....
Cisplatin resistance frequently occurs in esophageal squamous cell carcinoma (ESCC). The underlying mechanism for cisplatin resistance in ESCC remains largely obscure. Here we report that entinostat reversed cisplatin resistance in ESCC both in vitro and in vivo by induction of apoptosis and inhibition of cell proliferation, accompanied by a decrease of multidrug resistance gene 1 (MDR1), P-Src, Mcl-1, Cyclin D1 and an increase of cleaved PARP. MDR1 expression was associated with worsen survival of ESCC patients with cisplatin-based chemotherapy. Dasatinib potentiated entinostat to overcome cisplatin resistance. By inhibiting Src, dasatinib reduced the expression of MDR1 and Mcl-1. Furthermore, Obatoclax, an inhibitor of Mcl-1, obviously decreased the expression of MDR1, suggesting that entinostat might surmount cisplatin resistance in ESCC via a Src-Mcl-1-MDR1 pathway. Interestingly, cisplatin also enhanced the effect of entinostat both in vitro and in vivo. Our data disclose a molecular basis that entinostat reverses cisplatin resistance, and provide a promising strategy with combinatorial drugs to treat cisplatin resistant ESCC patients.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adult; Aged; Animals; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Survival; Cisplatin; Disease-Free Survival; Down-Regulation; Drug Resistance, Neoplasm; Esophageal Neoplasms; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Mice, Inbred BALB C; Middle Aged; Pyridines; Xenograft Model Antitumor Assays
PubMed: 29107111
DOI: 10.1016/j.canlet.2017.10.023 -
European Journal of Cell Biology Dec 2017BH3-only proteins constitute major proportion of pro-apoptotic members of B-cell lymphoma 2 (Bcl-2) family of apoptotic regulatory proteins and participate in embryonic... (Review)
Review
BH3-only proteins constitute major proportion of pro-apoptotic members of B-cell lymphoma 2 (Bcl-2) family of apoptotic regulatory proteins and participate in embryonic development, tissue homeostasis and immunity. Absence of BH3-only proteins contributes to autoimmune disorders and tumorigenesis. Bim (Bcl-2 Interacting Mediator of cell death), most important member of BH3-only proteins, shares a BH3-only domain (9-16 aa) among 4 domains (BH1-BH4) of Bcl-2 family proteins and highly pro-apoptotic in nature. Bim initiates the intrinsic apoptotic pathway under both physiological and patho-physiological conditions. Reduction in Bim expression was found to be associated with tumor promotion and autoimmunity, while overexpression inhibited tumor growth and drug resistance as cancer cells suppress Bim expression and stability. Apart from its role in normal homeostasis, Bim has emerged as a central player in regulation of tumorigenesis, therefore gaining attention as a plausible target for chemotherapy. Regulation of Bim expression and stability is complicated and regulated at multiple levels viz. transcriptional, post-transcriptional, post-translational (preferably by phosphorylation and ubiquitination), epigenetic (by promoter acetylation or methylation) including miRNAs. Furthermore, control over Bim expression and stability may be exploited to enhance chemotherapeutic efficacy, overcome drug resistance and select anticancer drug regimen as various chemotherapeutic agents exploit Bim as an executioner of cell death. Owing to its potent anti-tumorigenic activity many BH3 mimetics e.g. ABT-737, ABT-263, obatoclax, AT-101and A-1210477 have been developed and entered in clinical trials. It is more likely that in near future strategies commanding Bim expression and stability ultimately lead to Bim based therapeutic regimen for cancer treatment.
Topics: Animals; Antineoplastic Agents; Bcl-2-Like Protein 11; Humans; Molecular Targeted Therapy; Peptide Fragments; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2
PubMed: 29100606
DOI: 10.1016/j.ejcb.2017.09.002 -
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 -
The FEBS Journal Dec 2017The ERK1/2 signalling pathway is best known for its role in connecting activated growth factor receptors to changes in gene expression due to activated ERK1/2 entering... (Review)
Review
The ERK1/2 signalling pathway is best known for its role in connecting activated growth factor receptors to changes in gene expression due to activated ERK1/2 entering the nucleus and phosphorylating transcription factors. However, active ERK1/2 also translocate to a variety of other organelles including the endoplasmic reticulum, endosomes, golgi and mitochondria to access specific substrates and influence cell physiology. In this article, we review two aspects of ERK1/2 signalling at the mitochondria that are involved in regulating cell fate decisions. First, we describe the prominent role of ERK1/2 in controlling the BCL2-regulated, cell-intrinsic apoptotic pathway. In most cases ERK1/2 signalling promotes cell survival by activating prosurvival BCL2 proteins (BCL2, BCL-x and MCL1) and repressing prodeath proteins (BAD, BIM, BMF and PUMA). This prosurvival signalling is co-opted by oncogenes to confer cancer cell-specific survival advantages and we describe how this information has been used to develop new drug combinations. However, ERK1/2 can also drive the expression of the prodeath protein NOXA to control 'autophagy or apoptosis' decisions during nutrient starvation. We also describe recent studies demonstrating a link between ERK1/2 signalling, DRP1 and the mitochondrial fission machinery and how this may influence metabolic reprogramming during tumorigenesis and stem cell reprogramming. With advances in subcellular proteomics it is likely that new roles for ERK1/2, and new substrates, remain to be discovered at the mitochondria and other organelles.
Topics: Aniline Compounds; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Bridged Bicyclo Compounds, Heterocyclic; Drug Screening Assays, Antitumor; Humans; Indoles; MAP Kinase Signaling System; Mitochondrial Dynamics; Molecular Targeted Therapy; Neoplasm Proteins; Neoplasms; Oncogene Addiction; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides
PubMed: 28548464
DOI: 10.1111/febs.14122 -
Cancer Research Jul 2017Rational therapeutic approaches based on synthetic lethality may improve cancer management. On the basis of a high-throughput drug screen, we provide preclinical proof...
Rational therapeutic approaches based on synthetic lethality may improve cancer management. On the basis of a high-throughput drug screen, we provide preclinical proof of concept that targeting the mitochondrial Hsp90 chaperone network (mtHsp90) and inhibition of Bcl-2, Bcl-xL, and Mcl-1 is sufficient to elicit synthetic lethality in tumors recalcitrant to therapy. Our analyses focused on BH3 mimetics that are broad acting (ABT263 and obatoclax) or selective (ABT199, WEHI-539, and A1210477), along with the established mitochondrial matrix chaperone inhibitor gamitrinib-TPP. Drug combinations were tested in various therapy-resistant tumors and in murine model systems of melanoma, triple-negative breast cancer, and patient-derived orthotopic xenografts (PDX) of human glioblastoma. We found that combining BH3 mimetics and gamitrinib-TPP blunted cellular proliferation in a synergistic manner by massive activation of intrinsic apoptosis. In like manner, suppressing either Bcl-2, Bcl-xL, or Mcl-1 recapitulated the effects of BH3 mimetics and enhanced the effects of gamitrinib-TPP. Mechanistic investigations revealed that gamitrinib-TPP activated a PERK-dependent integrated stress response, which activated the proapoptotic BH3 protein Noxa and its downstream targets Usp9X and Mcl-1. Notably, in the PDX glioblastoma and BRAFi-resistant melanoma models, this drug combination safely and significantly extended host survival. Our results show how combining mitochondrial chaperone and Bcl-2 family inhibitors can synergize to safely degrade the growth of tumors recalcitrant to other treatments. .
Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Biomimetic Materials; Cell Line, Tumor; Cell Proliferation; Female; HSP90 Heat-Shock Proteins; Humans; Indoles; Male; Mice; Mice, SCID; Mitochondria; Peptide Fragments; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides; Xenograft Model Antitumor Assays
PubMed: 28522750
DOI: 10.1158/0008-5472.CAN-16-3424 -
ACS Synthetic Biology Sep 2017The deeply red-colored natural compound prodigiosin is a representative of the prodiginine alkaloid family, which possesses bioactivities as antimicrobial, antitumor,...
The deeply red-colored natural compound prodigiosin is a representative of the prodiginine alkaloid family, which possesses bioactivities as antimicrobial, antitumor, and antimalarial agents. Various bacteria including the opportunistic human pathogen Serratia marcescens and different members of the Streptomycetaceae and Pseudoalteromonadaceae produce prodiginines. In addition, these microbes generally accumulate many structurally related alkaloids making efficient prodiginine synthesis and purification difficult and expensive. Furthermore, it is known that structurally different natural prodiginine variants display differential bioactivities. In the herein described mutasynthesis approach, 13 different derivatives of prodigiosin were obtained utilizing the GRAS (generally recognized as safe) classified strain Pseudomonas putida KT2440. Genetic engineering of the prodigiosin pathway together with incorporation of synthetic intermediates thus resulted in the formation of a so far unprecedented structural diversity of new prodiginine derivatives in P. putida. Furthermore, the formed products allow reliable conclusions regarding the substrate specificity of PigC, the final condensing enzyme in the prodigiosin biosynthesis pathway of S. marcescens. The biological activity of prodigiosin toward modulation of autophagy was preserved in prodiginine derivatives. One prodiginine derivative displayed more potent autophagy inhibitory activity than the parent compound or the synthetic clinical candidate obatoclax.
Topics: Anti-Bacterial Agents; Genes, Synthetic; Genetic Enhancement; Metabolic Engineering; Mutation; Prodigiosin; Pseudomonas putida; Up-Regulation
PubMed: 28505410
DOI: 10.1021/acssynbio.7b00099 -
Oncotarget May 2017Drug combination therapies remain pivotal for the treatment of heterogeneous malignancies, such as glioblastomas. Here, we show a novel lethal interaction between Bcl-xL...
Drug combination therapies remain pivotal for the treatment of heterogeneous malignancies, such as glioblastomas. Here, we show a novel lethal interaction between Bcl-xL and c-myc inhibition accomplished by bromodomain protein inhibitors. Established, patient-derived xenograft and stem cell-like glioma cells were treated with the novel bromodomain protein inhibitors, JQ1 and OTX015, along with BH3-mimetics, ABT263 or Obatoclax. Synergy was assessed by calculation of CI values. Small interfering RNAs (siRNAs) were used for gene silencing and mechanistic studies. In vivo experiments were performed in a glioblastoma xenograft model. Single treatments with JQ1 and OTX015 had only moderate effects on the reduction of cellular viability. However, the combination treatment of BH3-mimetics along with JQ1 or OTX015 resulted in a highly synergistic reduction of cellular viability in a broad range of different model systems of malignant glioma. Similarly, knockdown of c-myc sensitized glioma cells for ABT263 mediated cell death. The enhanced loss of cellular viability in the combination treatment was mediated by activation of apoptosis with dissipation of mitochondrial membrane potential and caspase cleavage. The combination treatment led to a modulation of anti- and pro-apoptotic Bcl-2 family members with an increase in pro-apoptotic Noxa mediated by ATF4. Small interfering RNA mediated knockdown of Bak and Noxa protected glioma cells from ABT263/JQ1 mediated apoptosis. Finally, the combination treatment of ABT263 and OTX015 resulted in a regression of tumors and a significantly smaller tumor size as compared to single or vehicle treated tumors. Thus, these results warrant clinical testing for the drug combination of BH3-mimetics along with bromodain protein inhibitors.
Topics: Acetanilides; Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Azepines; Bcl-2-Like Protein 11; Caspases; Cell Line, Tumor; Cell Survival; Disease Models, Animal; Drug Synergism; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Glioma; Heterocyclic Compounds, 3-Ring; Humans; Membrane Potential, Mitochondrial; Mice; Proteins; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-myc; RNA, Small Interfering; Sulfonamides; Triazoles; Xenograft Model Antitumor Assays
PubMed: 28418907
DOI: 10.18632/oncotarget.16365