B cell lymphoma-2 (BCL-2) homology domain 3 (BH3) mimetics demonstrate differential activities dependent upon the functional repertoire of pro- and anti-apoptotic BCL-2 family proteins

Multifaceted roles of mitochondrial dysfunction in diseases: from powerhouses to saboteurs

The fact that mitochondria play a crucial part in energy generation has led to the nickname "powerhouses" of the cell being applied to them. They also play a significant role in many other cellular functions, including calcium signalling, apoptosis, and the creation of vital biomolecules. As a result, cellular function and health as a whole can be significantly impacted by mitochondrial malfunction. Indeed, malignancies frequently have increased levels of mitochondrial biogenesis and quality control. Adverse selection exists for harmful mitochondrial genome mutations, even though certain malignancies include modifications in the nuclear-encoded tricarboxylic acid cycle enzymes that generate carcinogenic metabolites. Since rare human cancers with mutated mitochondrial genomes are often benign, removing mitochondrial DNA reduces carcinogenesis. Therefore, targeting mitochondria offers therapeutic options since they serve several functions and are crucial to developing malignant tumors. Here, we discuss the various steps involved in the mechanism of cancer for which mitochondria plays a significant role, as well as the role of mitochondria in diseases other than cancer. It is crucial to understand mitochondrial malfunction to target these organelles for therapeutic reasons. This highlights the significance of investigating mitochondrial dysfunction in cancer and other disease research.

Non-phosphorylatable mutants of Ser184 lead to incomplete activation of Bax

The S184 residue of Bax is the target of several protein kinases regulating cell fate, including AKT. It is well-established that, in cellulo, the substitution of S184 by a non-phosphorylatable residue stimulates both the mitochondrial localization of Bax, cytochrome c release, and apoptosis. However, in in vitro experiments, substituted mutants did not exhibit any increase in their binding capacity to isolated mitochondria or liposomes. Despite exhibiting a significant increase of the 6A7 epitope exposure, substituted mutants remain limited in their ability to form large oligomers, suggesting that they high capacity to promote apoptosis in cells was more related to a high content than to an increased ability to form large pores in the outer mitochondrial membranes.

Gemcitabine Cooperates with Everolimus to Inhibit the Growth of and Sensitize Malignant Meningioma Cells to Apoptosis Induced by Navitoclax, an Inhibitor of Anti-Apoptotic BCL-2 Family Proteins

Simple Summary

Meningioma is the most common intracranial neoplasm derived from the arachnoid cap cells of the leptomeninges. Malignant meningioma is generally more aggressive than other meningioma and frequently recurs even after surgery and radiation therapy. Clinical trials have been performed on candidate drugs, including everolimus, an inhibitor of mammalian target of rapamycin. However, an effective standard systemic therapy has not yet been established and the prognosis of patients with malignant meningioma is still poor. We recently reported the radiosensitization effects of gemcitabine in malignant meningioma cells, which suggests its potential to enhance the efficacy of candidate drugs for meningioma. In the present study, we demonstrated that gemcitabine enhanced the therapeutic effects of everolimus in malignant meningioma cells, and these effects were further augmented by navitoclax, an inhibitor of anti-apoptotic BCL-2 family proteins, both in vitro and in vivo. The present results provide support for the clinical application of gemcitabine and navitoclax in combination with everolimus to the treatment of patients with malignant meningioma.

Abstract

Despite several clinical trials with encouraging findings, effective standard systemic therapies have yet to be established for malignant meningioma and the prognosis of these patients remains poor. Accumulating preclinical and clinical evidence suggests that gemcitabine is effective against malignant meningioma. To identify drugs with therapeutic effects that may be enhanced in combination with gemcitabine, we screened drugs that have been tested in preclinical and clinical trials for meningioma. In IOMM-Lee and HKBMM malignant meningioma cells, gemcitabine enhanced the growth inhibitory effects of the mTOR inhibitor everolimus, the clinical benefits of which have been demonstrated in patients with meningioma. The synergistic growth inhibitory effects of this combination were accompanied by cellular senescence characterized by an increase in senescence-associated β-galactosidase activity. To enhance the effects of this combination, we screened senolytic drugs that selectively kill senescent cells, and found that navitoclax, an inhibitor of anti-apoptotic BCL-2 family proteins, effectively reduced the number of viable malignant meningioma cells in combination with everolimus and gemcitabine by inducing apoptotic cell death. The suppression of tumor growth in vivo by the combination of everolimus with gemcitabine was significantly stronger than that by either treatment alone. Moreover, navitoclax, in combination with everolimus and gemcitabine, significantly reduced tumor sizes with an increase in the number of cleaved caspase-3-positive apoptotic cells. The present results suggest that the addition of gemcitabine with or without navitoclax to everolimus is a promising strategy that warrants further evaluation in future clinical trials for malignant meningioma.

Apoptosis and its therapeutic implications in neurodegenerative diseases

Neurodegenerative disorders are characterized by progressive loss of particular populations of neurons. Apoptosis has been implicated in the pathogenesis of neurodegenerative diseases, including Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. In this review, we focus on the existing notions relevant to comprehending the apoptotic death process, including the morphological features, mediators and regulators of cellular apoptosis. We also highlight the evidence of neuronal apoptotic death in Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. Additionally, we present evidence of potential therapeutic agents that could modify the apoptotic pathway in the aforementioned neurodegenerative diseases and delay disease progression. Finally, we review the clinical trials that were conducted to evaluate the use of anti-apoptotic drugs in the treatment of the aforementioned neurodegenerative diseases, in order to highlight the essential need for early detection and intervention of neurodegenerative diseases in humans.

Downregulation of lncRNA SNHG14 alleviates neurons injury by modulating the miR-181c-5p/BMF axis in ischemic stroke

PURPOSE

Our study aims to explore the role and mechanism of lncRNA small nucleolar RNA host gene 14 (SNHG14) in brain injury caused by ischemic stroke (IS).

METHODS

Middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation (OGD)-induced primary cortical neurons were used to construct in vitro and in vivo models of IS, respectively. Relative SNHG14, miR-181c-5p and Bcl-2-modifying factor (BMF) expression levels were detected by quantitative real-time PCR. MTT assay, EdU staining and flow cytometry were used to measure cell proliferation and apoptosis. The protein levels of apoptosis marker and BMF were determined using western blot analysis. ELISA assay was performed to assess cell inflammatory response and injury.

RESULTS

SNHG14 was upregulated and miR-181c-5p was downregulated in MCAO model and OGD-induced primary cortical neurons. Silencing of SNHG14 markedly promoted proliferation, restrained apoptosis and inflammatory response in OGD-induced primary cortical neurons to alleviate neurons injury. In terms of mechanism, miR-181c-5p could be sponged by SNHG14, and its inhibitor reversed the inhibition effect of SNHG14 silencing on OGD-induced neurons injury. Also, BMF was a target of miR-181c-5p, and its overexpression could reverse the suppressive effect of miR-181c-5p on OGD-induced neurons injury. Our data uncovered that BMF expression was positively regulated by SNHG14 and negatively regulated by miR-181c-5p.

CONCLUSION

Our results indicated that SNHG14 promoted neurons injury through regulating miR-181c-5p/BMF axis, suggesting that SNHG14 might be a potential target to alleviate IS-induced brain injury.

Verticillin A increases the BIMEL/MCL-1 ratio to overcome ABT-737-resistance in human colon cancer cells by targeting the MEK/ERK pathway

ABT-737, a small molecule BH-3 mimetic, is less effective against human colon cancers due to its resistance. Verticillin A is a natural compound, which was previously purified from verticillium-infected mushrooms. Hence, we aimed at overcoming the ABT737 resistance observed in CRC tumors by combining Verticillin A with ABT-737 and figuring out the potential mechanism. In this study, we observed that Verticillin A could sensitize colon cancer to ABT-737-induced cell death through induction of mitochondrial-dependent apoptosis. Verticillin A could significantly increase the BIMEL/MCL-1 ratio to overcome ABT737 resistance through the suppression of the MEK/ERK pathway. In addition, up-regulation of BIM protein levels to activate BAX translocation results in apoptosis induction. Altogether, our work suggested the potential application of Verticillin A as a MEK inhibitor in BH3-mimetic-based therapy.

Loss of BIM in T cells results in BCL-2 family BH3-member compensation but incomplete cell death sensitivity normalization

BIM is the master BH3-only BCL-2 family regulator of lymphocyte survival. To understand how long-term loss of BIM affects apoptotic resistance in T cells we studied animals with T cell-specific deletion of Bim. Unlike CD19^CREBim^fl/fl animals, LCK^CREBim^fl/fl mice have pronounced early lymphocytosis followed by normalization of lymphocyte counts over time. This normalization occurred in mature T cells, as thymocyte development and apoptotic sensitivity remained abnormal in LCK^CREBim^fl/fl mice. T cells from aged mice experienced normalization of their absolute cell numbers and responses against various apoptotic stimuli. mRNA expression levels of BCL-2 family proteins in CD4⁺ and CD8⁺ T cells from young and old mice revealed upregulation of several BH3-only proteins, including Puma, Noxa, and Bmf. Despite upregulation of various BH3 proteins, there were no differences in anti-apoptotic BCL-2 protein dependency in these cells. However, T cells had continued resistance to direct BIM BH3-induced mitochondrial depolarization. This study further highlights the importance of BIM in cell death maintenance in T cells and provides new insight into the dynamism underlying BH3-only regulation of T cell homeostasis versus induced cell death and suggests that CD4⁺ and CD8⁺ T cells compensate differently in response to loss of Bim.

Preferential targeting of MCL-1 by a hydrocarbon-stapled BIM BH3 peptide

BCL-2 family proteins are central regulators of apoptosis and represent prime therapeutic targets for overcoming cell death resistance in malignancies. However, plasticity of anti-apoptotic members, such as MCL-1, often allows for a switch in cell death dependency patterns that lie outside the binding profile of targeted BH3-mimetics. Therefore discovery of therapeutics that effectively inactivate all anti-apoptotic members is a high priority. To address this we tested the potency of a hydrocarbon stapled BIM BH3 peptide (BIM SAHB_A) to overcome both BCL-2 and MCL-1 apoptotic resistance given BIM’s naturally wide ranging affinity for all BCL-2 family multidomain members. BIM SAHB_A effectively killed diffuse large B-cell lymphoma (DLBCL) cell lines regardless of their anti-apoptotic dependence. Despite BIM BH3’s ability to bind all BCL-2 anti-apoptotic proteins, BIM SAHB_A’s dominant intracellular target was MCL-1 and this specificity was exploited in sequenced combination BH3-mimetic treatments targeting BCL-2, BCL-X_L, and BCL-W. Extending this MCL-1 functional dependence, mouse embryonic fibroblasts (MEFs) deficient in MCL-1 were resistant to mitochondrial changes induced by BIM SAHB_A. This study demonstrates the importance of understanding BH3 mimetic functional intracellular affinities for optimized use and highlights the diagnostic and therapeutic promise of a BIM BH3 peptide mimetic as a potential MCL-1 inhibitor.

Induction of neutrophil apoptosis by a Bcl-2 inhibitor reduces particulate matter-induced lung inflammation

Background. Environmental particulate matter exposure can cause various respiratory problems including aggravated asthma, decreased lung function and increased respiratory symptoms. However, the molecular mechanisms underlying PM-induced lung inflammation are incompletely understood. Effective therapeutic strategies are required.

Results. A mouse model of particulate matter-induced lung inflammation was used to identify the pathology and the molecular mechanisms for particulate matter-induced lung inflammation. The mouse model revealed that particulate matter induced neutrophil-dominated lung inflammation. Neutrophils derived from particulate matter-instilled mice showed decreased apoptosis and elevated Bcl-2 expression. Further studies in vav-Bcl-2 transgenic mice made it clear that Bcl-2 overexpression caused a marked increase in neutrophils in bronchoalveolar lavage fluid. Furthermore, we found that the Bcl-2 inhibitor ABT-199 reduced particulate matter-induced lung inflammation, and induced apoptosis of neutrophils in particulate matter-induced lung inflammation mice model.

Conclusions. Particulate matter-induced lung inflammation is mediated in part by inhibition of apoptosis of inflammatory cells. Bcl-2 is responsible for the reduced apoptosis of inflammatory cells in particulate matter-induced lung inflammation. The Bcl-2 selective inhibitor ABT-199 reduces particulate matter-induced lung inflammation by inducing the apoptosis of neutrophils and might be a promising drug for the treatment of particulate matter-induced lung inflammation.

Mitochondrial determinants of chemoresistance

Chemoresistance constitute nowadays the major contributor to therapy failure in most cancers. There are main factors that mitigate cell response to therapy, such as target organ, inherent sensitivity to the administered compound, its metabolism, drug efflux and influx or alterations on specific cellular targets, among others. We now know that intrinsic properties of cancer cells, including metabolic features, substantially contribute to chemoresistance. In fact, during the last years, numerous reports indicate that cancer cells resistant to chemotherapy demonstrate significant alterations in mitochondrial metabolism, membrane polarization and mass. Metabolic activity and expression of several mitochondrial proteins are modulated under treatment to cope with stress, making these organelles central players in the development of resistance to therapies. Here, we review the role of mitochondria in chemoresistant cells in terms of metabolic rewiring and function of key mitochondria-related proteins.

miR-1915-3p inhibits Bcl-2 expression in the development of gastric cancer

Many gene expressions changed during the development of gastric cancer, and non-coding RNAs including microRNAs (miRNAs) have been found to regulate cancer progression by participating in the process of tumor cell growth, migration, invasion and apoptosis. Our previous study has identified 29 miRNAs that are highly expressed in gastric cancer stem cells. One of these miRNAs, miR-1915-3p, has shown great potential as a diagnostic and prognostic biomarker for the cancers in liver, colon and thyroid, as well as in immune and kidney diseases. Herein, we found that miR-1915-3p exhibited low expression level in differentiated gastric cancer cell lines and gastric cancer tissues. It was found that the miR-1915-3p inhibited the growth of gastric cancer cells and thus promoted cell apoptosis. We discovered that the expressions of miR-1915-3p were significantly correlated to the lymph node metastasis and overall survival of patients with gastric cancer. Further study showed that there was a negative correlation between miR-1915-3p and Bcl-2 (B cell lymphoma/leukemia-2) expression, suggesting that Bcl-2 was a target gene of miR-1915-3p. Hence, miR-1915-3p possibly contributes to the development and progression of gastric cancer by inhibiting the anti-apoptotic protein Bcl-2. The finding provides a potential therapeutic strategy for gastric cancer.

Liposomal Permeabilization Assay to Study the Functional Interactions of the BCL-2 Family

Apoptosis, a form of programmed cell death that is important for development and homeostasis, is regulated by the BCL-2 family of proteins. Over twenty BCL-2 family members have been classified in three groups based on structural homology and function. The multidomain antiapoptotic proteins promote survival, whereas the multidomain and the BH3-only proapoptotic members induce cell death. Because the interaction among the BCL-2 family members occurs primarily at the mitochondrial outer membrane, biochemical assays using artificial liposomes have been developed to study the functional relationship between these proteins. The liposomal permeabilization assay is a cell-free system that relies on the ability of multidomain pro-apoptotic members to promote membrane permeabilization upon activation. By encapsulating a fluorophore and a quencher into liposomes, the degree of permeabilization can be quantified by the increase in fluorescence intensity as the fluorophore and quencher dissociate. The liposomal permeabilization assay has been used to delineate interactions among BCL-2 family members as well as to characterize peptides, small molecules, and lipids that modulate the function of BCL-2 family of proteins. Here, we describe in detail the permeabilization of liposomes induced by the interaction between BAX and BH3-only activator tBID.

Antimalarial Dihydroartemisinin triggers autophagy within HeLa cells of human cervical cancer through Bcl-2 phosphorylation at Ser70

BACKGROUND

As an effective antimalarial medicine, Dihydroartemisinin (DHA) has therapeutic potential on human cervical cancer. However, its working mechanism has not been elucidated.

PURPOSE

This study aimed to investigate the reversal effect of DHA on human cervical cancer HeLa cells, and explored its mechanism of action in vitro and in vivo.

STUDY DESIGN/METHODS

The effect and mechanism of DHA on HeLa cells was examined by using CCK-8 assay, flow cytometry, transmission electron microscopy, immunofluorescence, and Western blot analysis in human hepatocellular carcinoma cells.

RESULTS

In this study, it was confirmed that DHA had statistically equivalent anti-tumor efficiency in HeLa cells with a clinical chemotherapeutic agent of cisplatin. Meanwhile, DHA triggered autophagy, where LC3B-II expression was dose-dependently increased. Further, it was revealed that DHA promotes reactive oxygen species (ROS) generation, with DNA double-strand breaks (DSB) damage, as up-regulation of γH2AX protein and foci formation. Interestingly, we firstly demonstrated that DHA induced autophagy through promotion of the phosphorylation of Bcl-2 (Ser70), independent of the phosphorylated JNK1/2 (Thr183/Tyr185). Moreover, DHA-treated HeLa cells displayed an increase in the pro-autophagic protein Beclin-1 with downregulated the phospho-mTOR (Ser2448). Furthermore, upregulated pro-apoptotic protein Bak-1, but not Bax, suggesting Bak-1 is included in DHA-induced autophagy.

CONCLUSION

Therefore, DHA upregulates the phosphorylation of Bcl-2 (Ser70) and mTOR (Ser2448) and induces autophagic cell death in Hela cells. This study provided a mechanism to support DHA, an autophagy inducer, as a potential therapeutic agent for human cervical cancer.

Nur77 is a promoting factor in traumatic brain injury-induced nerve cell apoptosis

Traumatic brain injury (TBI) poses a serious threat to human health. TBI has a high mortality rate, resulting in a great burden on the affected individual's family as well as society as a whole. The incidence of craniocerebral fractures continues to rise as both the economy and transportation options grow, making it imperative that the mortality and disability rate of craniocerebral trauma be reduced. Nur77 is a transcription factor of the nuclear receptor superfamily. Following stimulation of extracellular apoptosis, Nur77 is involved in a variety of diseases as a powerful pro-apoptotic molecule. Here, we determined the effect and mechanism of Nur77 in TBI-induced nerve cell apoptosis in vitro and in vivo. We found that Nur77 and Bcl-2 protein expression increased as nerve cell apoptosis increased in TBI tissues. Furthermore, inhibition of Nur77 improved nerve cell injury by regulation of Bcl-2 and downstream pathways in vitro and in vivo.

Xihuang Pill Induces Apoptosis of Human Glioblastoma U-87 MG Cells via Targeting ROS-Mediated Akt/mTOR/FOXO1 Pathway

Xihuang pill (XHP), a traditional Chinese herbal formula, has long been used as an effective agent against multiple tumors. The aim of this study is to evaluate the effects of XHP on the growth inhibition and apoptosis in glioblastoma U-87 MG cells. Gas chromatography-mass spectrometry (GC-MS) was performed for constituent analysis of XHP. Cell viability, cell cycle arrest, generation of reactive oxygen species (ROS), and apoptosis were measured by CCK-8 assay, PI/RNase staining, DCFH-DA assay, TUNEL assay, Annexin V-FITC/PI double staining, and JC-1 assay, respectively. The role of XHP in the regulation of Akt/mTOR/FOXO1 interaction was clarified by using Western Blotting (WB), immunofluorescence (IF), pharmacological inhibitor or antioxidant, and siRNA silencing. The results suggested that XHP could inhibit U-87 MG cells growth and arrest cells in S-phase cell cycle significantly and that the generation of ROS, collapse of mitochondrial membrane potential, enhancement of Bax/Bcl-xL ratio, and reduction of the precursor forms of caspase-9 and caspase-3 caused by XHP prompted that a ROS-mediated mitochondria-dependent apoptosis was possibly involved. Furthermore, XHP affected the Akt/mTOR/FOXO1 pathway via inhibiting the phosphorylation of Akt, mTOR, and FOXO1 and increasing both prototype and nuclear translocation of FOXO1. Inhibition of Akt, mTOR, and FOXO1 by specific inhibitors or siRNA could interpose the apoptotic induction. In conclusion, we demonstrate for the first time that XHP may regulate glioblastoma U-87 MG cell apoptosis via ROS-mediated Akt/mTOR/FOXO1 pathway.

The Toxmatrix: Chemo-Genomic Profiling Identifies Interactions That Reveal Mechanisms of Toxicity

A chemical genomics "Toxmatrix" method was developed to elucidate mechanisms of cytotoxicity using neuronal models. Quantitative high-throughput screening (qHTS) was applied to systematically screen each toxicant against a panel of 70 modulators, drugs or chemicals that act on a known target, to identify interactions that either protect or sensitize cells to each toxicant. Thirty-two toxicants were tested at 10 concentrations for cytotoxicity to SH-SY5Y human neuroblastoma cells, with results fitted to the Hill equation to determine an IC₅₀ for each toxicant. Thirty-three toxicant:modulator interactions were identified in SH-SY5Y cells for 14 toxicants, as modulators that shifted toxicant IC₅₀ values lower or higher. The target of each modulator that sensitizes cells or protects cells from a toxicant suggests a mode of toxicant action or cellular adaptation. In secondary screening, we tested modulator-toxicant pairs identified from the SH-SY5Y primary screening for interactions in three differentiated neuronal human cell lines: dSH-SY5Y, conditionally immortalized dopaminergic neurons (LUHMES), and neural stem cells. Twenty toxicant-modulator pairs showed pronounced interactions in one or several differentiated cell models. Additional testing confirmed that several modulators acted through their primary targets. For example, several chelators protected differentiated LUHMES neurons from four toxicants by chelation of divalent cations and buthionine sulphoximine sensitized cells to 6-hydroxydopamine and 4-(methylamino)phenol hemisulfate by blocking glutathione synthesis. Such modulators that interact with multiple neurotoxicants suggest these may be vulnerable toxicity pathways in neurons. Thus, the Toxmatrix method is a systematic high-throughput approach that can identify mechanisms of toxicity and cellular adaptation.

Small molecule inhibitor TW-37 is tolerable and synergistic with chemotherapy in nasopharyngeal carcinoma

Chemotherapy is a crucial adjuvant therapy of advanced nasopharyngeal carcinoma (NPC). However, enhancing sensitivity and tolerance of chemotherapeutics in NPC treatment have been challenging. Both Bcl-2 and Mcl-1, 2 pro-survival proteins of Bcl-2 family, play essential roles on the chemotherapy tolerance of numerous cancers. In the present study, we explored the influences of TW-37, a small molecule inhibitor of Bcl-2 and Mcl-1, on the efficiency of chemotherapy for NPC. Oncomine cancer database shows that NPC tissues have higher expression of Bcl-2 and Mcl-1 than those of normal nasopharyngeal epithelial (NPE) tissues. And our results reveal that chemotherapeutics, Cisplatin (CDDP) and 5-Fluoracil (5-FU), result in the greater decrease of protein level of Bcl-2 and Mcl-1 in NPC cells than those in NPE cells. TW-37 does not have significant impact on the chemotherapeutics-treated NPE cell viability at a dosage that efficiently reduces chemotherapeutics-treated NPC cell viability. Moreover, impacts of TW-37 on the cell viability of chemotherapeutics-treated NPC cells are dependent on the expression of Bcl-2 and Mcl-1 in NPC cells. Further explorations suggest that TW-37 prominently promotes apoptosis in NPC cells under chemotherapeutics treatments but not in NPE cells. Meanwhile, TW-37 also remarkably reduces colony formation ability of chemotherapeutics-treated NPC cells. Importantly, in vivo models, TW-37 observably increases chemosensitivity of NPC tumors but has not markedly influence on the normal tissues in mice. In conclusion, our results point to TW-37 as a promising ancillary drug for the chemotherapy of NPC.

Directly targeting the mitochondrial pathway of apoptosis for cancer therapy using BH3 mimetics - recent successes, current challenges and future promise

Apoptosis within cancer cells is controlled by the BCL-2 family of proteins, making them powerful arbiters of cell fate in response to stress induced by neoplastic transformation as well as exposure to anti-cancer therapies. Many cancers evade pro-apoptotic stress signals by up-regulating anti-apoptotic proteins such as BCL-2, BCL-X_L or MCL-1 to maintain their survival. However, this may come at a cost, as these cancers may also become dependent on these anti-apoptotic proteins for survival. The development and deployment of BCL-2 family inhibitors (drugs that mimic the activity of pro-apoptotic BH3-only proteins or 'BH3 mimetics') is based on this paradigm, and the first potent and specific molecules are now being evaluated in clinical trials. We review the recent successes in this field, the challenges currently being faced, and the promising future ahead.

Autophagy inhibitor facilitates gefitinib sensitivity in vitro and in vivo by activating mitochondrial apoptosis in triple negative breast cancer

Epidermal growth factor receptor (EGFR) is over-expressed in about 50% of Triple negative breast cancers (TNBCs), but EGFR inhibitors have not been effective in treating TNBC patients. Increasing evidence supports that autophagy was related to drug resistance at present. However, the role and the mechanism of autophagy to the treatment of TNBC remain unknown. In the current study, we investigated the effect of autophagy inhibitor to gefitinib (Ge) in TNBC cells in vitro and in nude mice vivo. Our study demonstrated that inhibition of autophagy by 3-Methyladenine or bafilomycin A1 improved Ge's sensitivity to MDA-MB-231 and MDA-MB-468 cells, as evidence from stronger inhibition of cell vitality and colony formation, higher level of G0/G1 arrest and DNA damage, and these effects were verified in nude mice vivo. Our data showed that the mitochondrial-dependent apoptosis pathway was activated in favor of promoting apoptosis in the therapy of Ge combined autophagy inhibitor, as the elevation of BAX/Bcl-2, Cytochrome C, and CASP3. These results demonstrated that targeting autophagy should be considered as an effective therapeutic strategy to enhance the sensitivity of EGFR inhibitors on TNBC.

Stapled peptides: providing the best of both worlds in drug development

Peptide-based drug discovery has experienced a remarkable resurgence within the past decade due to the emerging class of inhibitors known as stapled peptides. Stapled peptides are therapeutic protein mimetics that have been locked within a specific conformational structure by hydrocarbon stapling. These peptides are highly important in selectively impairing disease-relevant protein–protein interactions and exhibit significant pharmacokinetic advantages over other forms of therapeutics in terms of affinity, specificity, size, synthetic accessibility and resistance to proteolytic degradation. A series of stapled peptides are currently in development, and the potential successes of these peptides, either as single-agent treatments or as combinational treatments with other therapeutic modalities, could potentially change the landscape of protein therapeutic development. Here, we provide examples of successful discovery efforts to illustrate the research strategies of stapled peptides in drug design and development.

Potential of apoptotic pathway-targeted cancer therapeutic research: Where do we stand?

Underneath the intricacy of every cancer lies mysterious events that impel the tumour cell and its posterity into abnormal growth and tissue invasion. Oncogenic mutations disturb the regulatory circuits responsible for the governance of versatile cellular functions, permitting tumour cells to endure deregulated proliferation, resist to proapoptotic insults, invade and erode normal tissues and above all escape apoptosis. This disruption of apoptosis has been highly implicated in various malignancies and has been exploited as an anticancer strategy. Owing to the fact that apoptosis causes minimal inflammation and damage to the tissue, apoptotic cell death-based therapy has been the centre of attraction for the development of anticancer drugs. Increased understanding of the molecular pathways underlying apoptosis has enabled scientists to establish unique approaches targeting apoptosis pathways in cancer therapeutics. In this review, we reconnoitre the two major pathways (intrinsic and extrinsic) targeted cancer therapeutics, steering toward chief modulators of these pathways, such as B-cell lymphoma 2 protein family members (pro- and antiapoptotic), inhibitor of apoptosis proteins, and the foremost thespian of extrinsic pathway regulator, tumour necrosis factor-related apoptosis-inducing agent. Together, we also will have a look from clinical perspective to address the agents (drugs) and therapeutic strategies adopted to target these specific proteins/pathways that have entered clinical trials.

Comparison of Immunomodulatory and Anticancer Activities in Different Strains of Tremella fuciformis Berk

Tremella fuciformis Berk (TF) is a common edible and medicinal mushroom, and has long been used in food and in Chinese medicine. It possesses anticancer, anti-inflammation, anti-oxidative, and neuroprotective abilities. Since their cultivation is a problem, TFs in Taiwan are primarily imported from China, which has a problem with pesticide residues. Thus, the question of whether the Taiwan cultivated TFs, T1, and T6 showed similar or even better results than TFs from China (CH) was assessed in the present study. The results of the physicochemical tests of these TFs showed that T1 extracted by hot water (T1H) has the highest concentration of polysaccharide; meanwhile, T6 extracted by cold water (T6C) showed the highest amount of protein. Regarding the immune modulatory effects of these TFs, hot water extracts of these TFs augmented significantly the inducible nitric oxide synthetase (iNOS), interleukin (IL)-6, and tumor necrosis factor (TNF)-[Formula: see text] mRNA expression than those of cold water extracts. On the other hand, the cold water extracts of TFs, especially of T1C, obviously suppressed cancer cell survival better than those of hot water extracts. Interestingly, we found that hot water extracts of TFs may augment necrotic cell death, whereas, cold water extracts of TFs induce apoptosis. Furthermore, we also showed that these TFs activate caspase-3 cleavage, up regulate the Bax/Bcl-2 ratio, and decrease MMP-9 expressions in PC-3 cells. Taken together, our results indicated that T1 and T6 strains of TFs showed the similar immune modulatory and anticancer abilities were better than the CH strain of TFs.

Heart mitochondria and calpain 1: Location, function, and targets

Calpain 1 is an ubiquitous Ca(2+)-dependent cysteine protease. Although calpain 1 has been found in cardiac mitochondria, the exact location within mitochondrial compartments and its function remain unclear. The aim of the current review is to discuss the localization of calpain 1 in different mitochondrial compartments in relationship to its function, especially in pathophysiological conditions. Briefly, mitochondrial calpain 1 (mit-CPN1) is located within the intermembrane space and mitochondrial matrix. Activation of the mit-CPN1 within intermembrane space cleaves apoptosis inducing factor (AIF), whereas the activated mit-CPN1 within matrix cleaves complex I subunits and metabolic enzymes. Inhibition of the mit-CPN1 could be a potential strategy to decrease cardiac injury during ischemia-reperfusion.

Bcl-2 family of proteins as drug targets for cancer chemotherapy: the long way of BH3 mimetics from bench to bedside

Bcl-2 proteins are key determinants in the life-death balance. In recent years, proteins in this family have been identified as drug targets in the design of new anti-tumor therapies. Advances in the knowledge of the mechanism of action of anti-apoptotic and pro-apoptotic members of the Bcl-2 family have enabled the development of the so-called 'BH3 mimetics'. These compounds act by inhibiting anti-apoptotic proteins of the family, imitating the function of the BH3-only subset of pro-apoptotic members. Combinations of BH3-mimetics with anti-tumor drugs are being evaluated in both preclinical models and clinical trials. Recent advances in these approaches will be reviewed.

Putting the pieces together: How is the mitochondrial pathway of apoptosis regulated in cancer and chemotherapy?

In order to solve a jigsaw puzzle, one must first have the complete picture to logically connect the pieces. However, in cancer biology, we are still gaining an understanding of all the signaling pathways that promote tumorigenesis and how these pathways can be pharmacologically manipulated by conventional and targeted therapies. Despite not having complete knowledge of the mechanisms that cause cancer, the signaling networks responsible for cancer are becoming clearer, and this information is serving as a solid foundation for the development of rationally designed therapies. One goal of chemotherapy is to induce cancer cell death through the mitochondrial pathway of apoptosis. Within this review, we present the pathways that govern the cellular decision to undergo apoptosis as three distinct, yet connected puzzle pieces: (1) How do oncogene and tumor suppressor pathways regulate apoptosis upstream of mitochondria? (2) How does the B-cell lymphoma 2 (BCL-2) family influence tumorigenesis and chemotherapeutic responses? (3) How is post-mitochondrial outer membrane permeabilization (MOMP) regulation of cell death relevant in cancer? When these pieces are united, it is possible to appreciate how cancer signaling directly impacts upon the fundamental cellular mechanisms of apoptosis and potentially reveals novel pharmacological targets within these pathways that may enhance chemotherapeutic success.