DYRK1A suppression restrains Mcl-1 expression and sensitizes NSCLC cells to Bd-2 inhibitors

Objective:Mcl-1 overexpression confers acquired resistance to Bcl-2 inhibitors in non-small cell lung cancer(NSCLC),but no direct Mcl-1 inhibitor is currently available for clinical use.Thus,novel therapeutic strategies are urgently needed to target Mcl-1 and sensitize the anti-NSCLC activity of Bcl-2 inhibitors.Methods:Cell proliferation was measured using sulforhodamine B and colony formation assays,and apoptosis was detected with Annexin V-FITC staining.Gene expression was manipulated using siRNAs and plasmids.Real-time PCR and Western blot were used to measure mRNA and protein levels.Immunoprecipitation and immunofluorescence were used to analyze co-localization o f dual specificity tyrosine-phosphorylation-regulated kinase 1A(DYRK1A)and Mcl-1.Results:Suppression of DYRK1A resulted in reduced Mcl-1 expression in NSCLC cells,whereas overexpression of DYRK1A significantly increased Mcl-1 expression.Suppression of DYRK1A did not alter Mcl-1 mRNA levels,but did result in an accelerated degradation o f Mcl-1 protein in NSCLC cells.Furthermore,DYRK1A mediated proteasome-dependent degradation o f Mcl-1 in NSCLC cells,and DYRK1A co-localized with Mcl-1 in NSCLC cells and was co-expressed with Mcl-1 in tumor samples from lung cancer patients,suggesting that Mcl-1 may be a novel DYRK1A substrate.We showed that combined therapy with harmine and Bcl-2 antagonists significantly inhibited cell proliferation and induced apoptosis in NSCLC cell lines as well as primary NSCLC cells.Conclusions:Mcl-1 is a novel DYRK1A substrate,and the role of DYRK1A in promoting Mcl-1 stability makes it an attractive target for decreasing Bcl-2 inhibitor resistance.

Recent advances in developing small-molecule inhibitors against SARS-CoV-2

The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world.Even though several COVID-19 vaccines are currently in distribution worldwide,with others in the pipeline,treatment modalities lag behind.Accordingly,researchers have been working hard to understand the nature of the virus,its mutant strains,and the pathogenesis of the disease in order to uncover possible drug targets and effective therapeutic agents.As the research continues,we now know the genome structure,epidemiological and clinical features,and pathogenic mechanism of SARS-CoV-2.Here,we summarized the potential therapeutic targets involved in the life cycle of the virus.On the basis of these targets,small-molecule prophylactic and therapeutic agents have been or are being developed for prevention and treatment of SARS-CoV-2 infection.

JTE-522-induced apoptosis in human gastric adenocarinoma cell line AGS cells by caspase activation accompanying cytochrome C release,membrane translocation of Bax and loss of mitochondrial membrane potential

AIM: To investigate the role of the mitochondrial pathway in JTE-522-induced apoptosis and to investigate the relationship between cytochrome C release, caspase activity and loss of mitochondrial membrane potential (Deltapsim). METHODS: Cell culture, cell counting, ELISA assay, TUNEL, flow cytometry, Western blot and fluorometric assay were employed to investigate the effect of JTE-522 on cell proliferation and apoptosis in AGS cells and related molecular mechanism. RESULTS: JTE-522 inhibited the growth of AGS cells and induced the apoptosis. Caspases 8 and 9 were activated during apoptosis as judged by the appearance of cleavage products from procaspase and the caspase activities to cleave specific fluorogenic substrates. To elucidate whether the activation of caspases 8 and 9 was required for the apoptosis induction, we examined the effect of caspase-specific inhibitors on apoptosis. The results showed that caspase inhibitors significantly inhibited the apoptosis induced by JTE-522. In addition, the membrane translocation of Bax and cytosolic release of cytochrome C accompanying with the decrease of the uptake of Rhodamin 123, were detected at an early stage of apoptosis. Furthermore, Bax translocation, cytochrome C release, and caspase 9 activation were blocked by Z-VAD.fmk and Z-IETD-CHO. CONCLUSION: The present data indicate a crucial association between activation of caspases 8, 9, cytochrome C release, membrane translocation of Bax, loss of Deltapsim and JTE-522-induced apoptosis in AGS cells.

MG132 Inhibits Myocardial Ischemia-reperfusion Injury by Regulating Apoptotic Pathway

Objectives To administrated proteasome inhibitor-MG-132 prior to reperfusion in rat myocardial ischemia-reperfusion model to determine whether MG-132 could reduce myocytic apoptosis. Methods and results MG-132 （0. 75 mg/kg in 2 ml DMSO） injection 5 min prior to reperfusion resulted significant reduction of myocardial reperfusion injury. This effect was accompanied by reduced polymorphonuclear neutrophils （PMN） infiltration in myocardial region surrounding the myocardial infarct, reduced apoptosis in cardiac myocytes, reduced NF-κB activation, as determined by electron microscopy, histology, immunohistochemistry, the terminal deoxynucleotidyl transferase-mediated nick endlabeling （TUNEL） method, reverse transcription-polymerase chain reaction. Functional effects of MG-132 on PMN accumulation, activation of nuclear factor kappa B （p65 mRNA and protein levels ）, and apoptosis were characterized in rat myocardial tissue. MG132 time-dependently inhibited myocardial p65 mRNA expression and reduced myocardial apoptotic index （AI） after reperfusion for 2 h, 6 h and 24 h （ P 〈 0. 01 ）. Moreover, MG-132 time-dependently decreased Bax protein levels, while increased Bcl-2 protein levels in ischemic and reperfused myocardium （ P 〈 0. 05 ）, its effect peaked after reperfusion for 24 h. Conclusions Our results demonstrate that MG-132 reduced myocardial reperfusion injury by inhibiting myosytic apoptotic cell death and blocking activation of NF-κB, down-regulating Bax expression and up-regulating Bcl-2 expression as well as el evating Bcl-2/Bax ratio.

Synthesis of 4-（2-Phenylhydrazono）-l-（4-phenylthiazol-2-yl）- 1H-pyrazol-5（4H）-one Compounds and Characterization of Their Affinities to Anti-apoptotic Bcl-2 Family Proteins

Organic compounds containing the thiazol-2-yl-lH-pyrazol-5（4H）-one moiety are known to be associated with versatile pharmacological applications. In this study, we describe the methods for preparing 4-（2-phenylhydrazono）- l-（4-phenylthiazol-2-yl）-1H-pyrazol-5（4H）-one compounds. A set of 26 compounds were synthesized with overall yields ranging between 37%-92%. They were tested in a fluorescence polarization-based binding assay against three anti-apoptotic Bcl-2 family proteins, including Bcl-xL, Bcl-2, and Mcl-1. Our results indicate that this class of compounds are not effective inhibitors of these anti-apoptotic Bcl-2 family proteins. Their apoptosis-inducing ef- fects are possibly due to BAX activation as suggested by Gavathiotis et al. in their recent study. However, other possibilities should not be ignored. In addition, a crystal structure obtained by us reveals that the exocyclic double bond in the molecular structure of this class of compounds is in the （Z）-configuration.

Combined Effects of Capsaicin and HA14-1 in Inducing Apoptosis in Melanoma Cells

Abnormal regulation of apoptosis is an important aspect of tumour development. Capsaicin, an extract of red chilli peppers, has been shown to inhibit growth of melanoma and other malignant cell lines and HA14-1 is an organic compound that directly induces apoptosis by binding to Bcl-2 protein. The aim of this work was to investigate whether combination therapy with capsaicin and HA14-1 might hold any promise for the treatment of melanoma. Three melanoma cell lines of a range of aggressive potential, melanocytes and fibroblasts were examined, looking at the effects of both drugs singly and in combination on cell viability and induction of apoptosis. This comparative study showed that melanoma cells and melanocytes have a similar sensitivity to capsaicin while fibroblasts are more resistant to it. HA14-1, as expected, induced apoptosis in all cells at relatively low concentrations. A combination of the two agents produced the expected results of an additive effect for 2 (HBL and A375SM) out of 3 melanoma cell lines in inducing apoptosis, but encouragingly for the most metastatically aggressive cancer cell line (C8161), a combination of the two showed a synergistic induction of apoptosis.

Systems analysis of the“weights”of Bcl-2 and Mcl-1 in mitochondrial apoptosis pathway establishes a predictor for best drug combination ratio

Background:Inhibitors of B-cell CLL/Iymphoma 2(Bcl-2)family proteins have shown hope as antitumor drugs.While the notion that it is efficient to coordinate,balance,and neutralize both arms of the anti-apoptotic Bcl-2 family has been validated in many cancer cells,the weights of the two arms contributing to apoptosis inhibition have not been explored.This study analyzed the best combination ratio for different Bcl-2 selective inhibitors.Methods:We used a previously established mathematical model to study the weights of Bcl-2(representing both Bcl-2 and BcI-xL in this study)and myeloid cell leukemia-1(Mcl-1).Correlation and single-parameter sensitivity analysis were used to find the major molecular determinants for Bcl-2 and Mcl-1 dependency,as well as their weights.Biological experiments were used to verify the mathematical model.Results:Bcl-2 protein level and Mcl-1 protein level,production,and degradation rates were the major molecular determinants for Bcl-2 and Mcl-1 dependency.The model gained agreement with the experimental assays for ABT-737/A-1210477 and ABT-737/compound 5 combination effect in MCF-7 and MDA-MB-231.Two sets of equations composed of Bcl-2 and Mcl-1 levels were obtained to predict the best combination ratio for Bcl-2 inhibitors with Mcl-1 inhibitors that stabilize and downregulate Mcl-1,respectively.Conclusions:The two sets of equations can be used as tools to bypass time-consuming and laborious experimental screening to predict the best drug combination ratio for treatment.

Targeting BCL2 pathways in CLL: a story of resistance and ingenuity

Chronic lymphocytic leukemia(CLL)is common amongst leukemic malignancies,prompting dedicated investigation throughout the years.Over the last decade,the treatment for CLL has significantly advanced with agents targeting B-cell lymphoma 2(BCL2),Bruton's tyrosine kinase,and CD20.Single agents or combinations of these targets have proven efficacy.Unfortunately,resistance to one or multiple of the new treatment targets develops.Our review investigates various mechanisms of resistance to BCL2 inhibitors,including mutations in BCL2,alterations in the Bcl protein pathway,epigenetic modifications,genetic heterogeneity,Richter transformation,and alterations in oxidative phosphorylation.Additionally,the review will discuss potential avenues to overcome this resistance with novel agents such as bispecific antibodies,Bruton's tyrosine kinase(BTK)degraders,non-covalent BTK inhibitors,and chimeric antigen receptor T(CART).