Discovery of a small-molecule bromodomain-containing protein 4 inhibitor that induces AMP-activated protein kinase-modulated autophagy-associated cell death in breast cancer

OBJECTIVE To discover a small-molecule bromodomain-containing protein 4(BRD4)inhibitor that induces AMP-activated protein kinase-modulated autophagy-associated cell death in breast cancer and exploreits potential mechanisms.METHODS BRD4 interactors were analyzed by PPI network prediction and The Cancer Genome Atlas(TCGA)analysis.The interaction between BRD4 and AMPK was confirmed by co-immunoprecipitation assay.Novel BRD4 inhibitors were designed and synthesized based upon pharmacophore analysis of BRD4(1),then screened by antiproliferative activity and Alpha Screen of BRD4(1).The selectivity of the best candidate compound 8f was validated by co-crystallization,FRET assay and co-immuno precipitation assay.The mechanisms of 8f were investigated by fluorescence microscopy,electron microscopy,Western blotting,immunocytochemistry,si RNA and GFP-m RFP-LC3 plasmid transfections,as well as immunohistochemistry and immunofluorescence.Potential mechanisms were discovered by i TRAQ-based proteomics analysis and the therapeutic effect of 8f was assessed by xenograft breast cancer mouse and zebrafish models.RESULTS We identified that BRD4 interacted with AMPK,which was remarkably downregulated in breast cancer.We next designed and synthesized 49 candidate compounds,and eventually discovered a selective small-molecule inhibitor of BRD4(8f).Subsequently,8f was discovered to induce autophagyassociated cell death(ACD)by BRD4-AMPK interaction,and thus activating AMPK-m TOR-ULK1-modulated autophagic pathway in breast cancer cells.Interestingly,the i TRAQ-based proteomics analyses revealed that 8f induced ACD pathways,involved in HMGB1,VDAC1/2 and e EF2.Moreover,8f displayed a therapeutic potential on both xenograft breast cancer mouse and zebrafish models.CONCLUSION We discovered a novel small-molecule inhibitor of BRD4 that induces BRD4-AMPK-modulated ACD in breast cancer,which may provide a candidate drug for future cancer therapy.

Tyrosine kinase inhibitors:Multi-targeted or single-targeted?

Since in most tumors multiple signaling pathways are involved,many of the inhibitors in clinical development are designed to affect a wide range of targeted kinases.The most important tyrosine kinase families in the development of tyrosine kinase inhibitors are the ABL,SCR,platelet derived growth factor,vascular endothelial growth factor receptor and epidermal growth factor receptor families.Both multi-kinase inhibitors and singlekinase inhibitors have advantages and disadvantages,which are related to potential resistance mechanisms,pharmacokinetics,selectivity and tumor environment.In different malignancies various tyrosine kinases are mutated or overexpressed and several resistance mechanisms exist.Pharmacokinetics is influenced by interindividual differences and differs for two single targeted inhibitors or between patients treated by the same tyrosine kinase inhibitor.Different tyrosine kinase inhibitors have various mechanisms to achieve selectivity,while differences in gene expression exist between tumor and stromal cells.Considering these aspects,one type of inhibitor can generally not be preferred above the other,but will depend on the specific genetic constitution of the patient and the tumor,allowing personalized therapy.The most effective way of cancer treatment by using tyrosine kinase inhibitors is to consider each patient/tumor individually and to determine the strategy that specifically targets the consequences of altered(epi)genetics of the tumor.This strategy might result in treatment by a single multi kinase inhibitor for one patient,but in treatment by a couple of single kinase inhibitors for other patients.

Design,synthesis,and evaluation of fluoroquinolone derivatives as microRNA-21 small-molecule inhibitors

MicroRNA-21(miRNA-21)is highly expressed in various tumors.Small-molecule inhibition of miRNA-21 is considered to be an attractive novel cancer therapeutic strategy.In this study,fluoroquinolone derivatives A1eA43 were synthesized and used as miRNA-21 inhibitors.Compound A36 showed the most potent inhibitory activity and specificity for miRNA-21 in a dual-luciferase reporter assay in HeLa cells.Compound A36 significantly reduced the expression of mature miRNA-21 and increased the protein expression of miRNA-21 target genes,including programmed cell death protein 4(PDCD4)and phosphatase and tensin homology deleted on chromosome ten(PTEN),at 10 μM in HeLa cells.The Cell Counting Kit-8 assay(CCK-8)was used to evaluate the antiproliferative activity of A36;the results showed that the IC_(50) value range of A36 against six tumor cell lines was between 1.76 and 13.0 μM.Meanwhile,A36 did not display cytotoxicity in BEAS-2B cells(lung epithelial cells from a healthy human donor).Furthermore,A36 significantly induced apoptosis,arrested cells at the G_(0)/G_(1) phase,and inhibited cell-colony formation in HeLa cells.In addition,mRNA deep sequencing showed that treatment with A36 could generate 171 dysregulated mRNAs in HeLa cells,while the expression of miRNA-21 target gene dual-specificity phosphatase 5(DUSP5)was significantly upregulated at both the mRNA and protein levels.Collectively,these findings demonstrated that A36 is a novel miRNA-21 inhibitor.

Research progress regarding programmed cell death 1/programmed cell death ligand 1 inhibitors combined with targeted therapy for treating hepatocellular carcinoma

In recent years,a number of targeted therapeutic agents have achieved success in phase III trials in patients with advanced hepatocellular carcinoma(HCC),including sorafenib,lenvatinib,and regorafenib.Immunotherapy is considered to be an effective treatment for advanced HCC.Immune checkpoint inhibitors targeting programmed cell death 1(PD-1)/programmed cell death ligand 1(PDL1)are important antitumor immunotherapy agents that represent breakthroughs in the treatment of advanced HCC.However,treating advanced HCC is still a great challenge,and the need for new treatments remains urgent.This review briefly summarizes the research progress in the use of PD-1/PD-L1 inhibitors combined with targeted therapy for treating HCC.

Targeted and immune therapies for hepatocellular carcinoma:Predictions for 2019 and beyond

Systemic therapy for hepatocellular carcinoma(HCC) has markedly advanced since the survival benefit of a molecular targeted agent, sorafenib, were demonstrated in the SHARP and Asia Pacific trials in 2007. Treatment options for patients with advanced HCC increased by sorafenib, and long-term survival for patients with advanced stage HCC has become possible to some extent. However,development of a more potent first-line novel molecular targeted agent replacing sorafenib and a potent second-line agent after disease progression on or intolerant to sorafenib has been warranted because sorafenib lacks tumor shrinking/necrotizing effects and induces relatively severe adverse events such as hand foot skin reaction. Many agents in the 1 st line and 2 nd line setting were attempted to develop between 2007 and 2016, but all of these clinical trials failed.On the other hand, clinical trials of 4 agents(regorafenib, lenvatinib,cabozantinib, and ramucirumab) succeeded in succession in 2017 and 2018, and their use in clinical practice is possible(regorafenib and lenvatinib) or underway(cabozantinib and ramucirumab). Furthermore, all of 5 clinical trials of combination therapy with transcatheter chemoembolization(TACE) plus a molecular targeted agent failed to date, however, the combination of TACE and sorafenib(TACTICS trials) was reported to be successful and presented at ASCO in 2018. Phase 3 clinical trials of immune checkpoint inhibitors and a combination therapy of immune checkpoint inhibitors and molecular targeted agents are also ongoing, which suggests treatment paradigm of HCC in all stages from early,intermediate and advanced stage, is expected to be changed drastically in the very near future.

Targeted therapies in epithelial ovarian cancer: Molecular mechanisms of action

Ovarian cancer is the leading cause of death in women with gynecological cancer. Most patients are diagnosed at an advanced stage and have a poor prognosis.Currently, surgical tumor debulking, followed by platinum- and taxane-based chemotherapy is the standard treatment for advanced ovarian cancer. However, these patients are at great risk of recurrence and emerging drug resistance. Therefore, novel treatment strategies are required to improve outcomes for women with advanced ovarian cancer. A variety of molecular targeted agents, the majority of which are monoclonal antibodies and small-molecule protein-kinase inhibitors, have been explored in the management of ovarian cancer. The targets of these agents include angiogenesis, the human epidermal growth factor receptor family, ubiquitinproteasome pathway, epigenetic modulators, poly(ADPribose) polymerase (PARP), and mammalian target of rapamycin (mTOR) signaling pathway, which are aberrant in tumor tissue. The antiangiogenic agent, bevacizumab, has been reported as the most effective targeted agent and should be included in the standard chemotherapeutic regimen for advanced ovarian cancer. PARP inhibitors, which are mainly used in breast and ovarian cancer susceptibility gene-mutated patients, and mTOR inhibitors are also attractive treatment strategies, either alone or combination with chemotherapy, for ovarian cancer. Understanding the tumor molecular biology and identification of predictive biomarkers are essential steps for selection of the best treatment strategies. This article reviews the molecular mechanisms of the most promising targeted agents that are under early phase clinical evaluation for ovarian cancer.

Targeted therapy of gastrointestinal stromal tumours

Gastrointestinal stromal tumours(GISTs) are mesen-chymal neoplasms originating in the gastrointestinal tract, usually in the stomach or the small intestine, and rarely elsewhere in the abdomen. The malignant potential of GISTs is variable ranging from small lesions with a benign behaviour to fatal sarcomas. The majo-rity of the tumours stain positively for the CD-117(KIT) and discovered on GIST-1(DOG-1 or anoctamin 1) expression, and they are characterized by the presence of a driver kinase-activating mutation in either KIT or platelet-derived growth factor receptor α. Although surgery is the primary modality of treatment, almost half of the patients have disease recurrence following surgery, which highlights the need for an effective adjuvant therapy. Traditionally, GISTs are considered chemotherapy and radiotherapy resistant. With the advent of targeted therapy(tyrosine kinase inhibitors), there has been a paradigm shift in the management of GISTs in the last decade. We present a comprehensive review of targeted therapy in the management of GISTs.

Molecularly targeted therapy for advanced hepatocellular carcinoma-a drug development crisis?

Hepatocellular carcinoma is the fastest growing cause of cancer related death globally. Sorafenib,a multitargeted kinase inhibitor,is the only drug proven to improve outcomes in patients with advanced disease offering modest survival benefit. Although comprehensive genomic mapping has improved understanding of the genetic aberrations in hepatocellular cancer(HCC),this knowledge has not yet impacted clinical care. The last few years have seen the failure of several first and second line phase Ⅲ clinical trials of novel molecularly targeted therapies,warranting a change in the way new therapies are investigated in HCC. Potential reasons for these failures include clinical and molecular heterogeneity,trial design and a lack of biomarkers. This review discusses the current crisis in HCC drug development and how we should learn from recent trial failures to develop a more effective personalised treatment paradigm for patients with HCC.

Methodology of drug screening and target identification for new necroptosis inhibitors

Apoptosis has been considered as the only form of regulated cell death for a long time. However, a novel form of programmed cell death called necroptosis was recently reported. The process of necroptosis is regulated and plays a critical role in the occurrence and development of multiple human diseases. Thus,the study on the molecular mechanism of necroptosis and its effective inhibitors has been an attractive field for researchers. Herein, we introduce the molecular mechanism of necroptosis and focus on the literature about necroptosis drug screening in recent years. In addition, the identification of the critical drug targets of the necroptosis is also discussed.

Molecularly targeted therapies for advanced or metastatic non-small-cell lung carcinoma

Non-small-cell lung cancer(NSCLC)remains the leading cause of cancer-related death in both men and women in the United States.Platinum-based doublet chemotherapy has been a standard for patients with advanced stage disease.Improvements in overall survival and quality of life have been modest.Improved knowledge of the aberrant molecular signaling pathways found in NSCLC has led to the development of biomarkers with associated targeted therapeutics,thus changing the treatment paradigm for many NSCLC patients.In this review,we present a summary of many of the currently investigated biologic targets in NSCLC,discuss their current clinical trial status,and also discuss the potential for development of other targeted agents.

Immunosuppressive potency of mechanistic target of rapamycin inhibitors in solid-organ transplantation

Mammalian target of rapamycin, also known as me-chanistic target of rapamycin(m TOR) is a protein kinase that belongs to the PI3K/AKT/m TOR signaling pathway, which is involved in several fundamental cellular functions such as cell growth, proliferation, and survival. This protein and its associated pathway have been implicated in cancer development and the regulation of immune responses, including the rejection response generated following allograft transplantation. Inhibitors of m TOR(m TORi) such as rapamycin and its derivative everolimus are potent immunosuppressive drugs that both maintain similar rates of efficacy and could optimize the renal function and diminish the side effects compared with calcineurin inhibitors. These drugs are used in solid-organ transplantationtoinduceimmunosuppression while also promoting the expansion of CD4+CD25+FOXP3+ regulatory T-cells that could favor a scenery of immu-nological tolerance. In this review, we describe the mechanisms by which inhibitors of m TOR induce sup-pression by regulation of these pathways at different levels of the immune response. In addition, we par-ticularly emphasize about the main methods that are used to assess the potency of immunosuppressive drugs, highlighting the studies carried out about immunosuppressive potency of inhibitors of m TOR.

Neuroendocrine tumors resistant to mammalian target of rapamycin inhibitors:A difficult conversion from biology to the clinic

Deregulation of the phosphoinositide 3-kinase(PI3K)/protein kinase B(Akt)- mammalian target of rapamycin(m TOR) signaling pathway is one of the most commonlyinvolved pathways in tumorigenesis. It has also been reported as altered in neuroendocrine tumors(NETs). m TOR inhibitors used in clinical practice are derived from rapamycin,an anti-cancer agent also used as an immunosuppressor after organ transplantation. Everolimus and temsirolimus are the two rapamycin-derived m TOR inhibitors used in NETs. Notably everolimus has been approved in advanced progressive well/moderatelydifferentiated pancreatic NETs(p NETs). It inhibits specifically the m TORC1 subunit of m TOR,not interacting with m TORC2. Although everolimus produced a significant prolongation of progression-free survival a number of patients with p NETs do not benefit from the drug due to early or late progression. Two supposed mechanisms of resistance to m TOR inhibitors are Akt and PI3 K activation,by means of m TORC2 and insulin growth factor(IGF)- IGF receptor signaling,respectively. BEZ235 is a multi-targeted inhibitor binding to PI3 K,m TORC1 and m TORC2,therefore potentially turning off all the supposed molecular targets of resistance to everolimus. The two clinical trials designed in p NETs were stopped early due to unmet statistical endpoint and the global clinical development of BEZ235 was also halted. Tolerability of this drug was challenging and conditioned the feasibility of therapy. The BEZ experience is an example of the huge difference between the preclinical and clinical setting and prompts us to pay more attention to the phase Ⅰ step of clinical development and the design of phase Ⅱ clinical trials.

Mammalian target of rapamycin inhibitors after post-transplant hepatocellular carcinoma recurrence:Is it too late?

BACKGROUND Mammalian target of rapamycin(mTOR)inhibitors have been shown to reduce the risk of tumour recurrence after liver transplantation for hepatocellular carcinoma(HCC).However,their role in established post-transplant HCC recurrence is uncertain.AIM To investigate whether mTOR inhibitor offers a survival benefit in posttransplant HCC recurrence.METHODS A retrospective study of 143 patients who developed HCC recurrence after liver transplantation was performed.They were divided into 2 groups based on whether they had received mTOR inhibitor-based immunosuppression.The primary endpoint was post-recurrence survival.RESULTS Seventy-nine(55%)patients received an mTOR inhibitor-based immunosuppressive regime,while 64(45%)patients did not.The mTOR inhibitor group had a lower number of recurrent tumours(2 vs 5,P=0.02)and received more active treatments including radiotherapy(39 vs 22%,P=0.03)and targeted therapy(59 vs 23%,P<0.001).The median post-recurrence survival was 21.0±4.1 mo in the mTOR inhibitor group and 11.2±2.5 mo in the control group.Multivariate Cox regression analysis confirmed that mTOR inhibitor therapy was independently associated with improved post-recurrence survival(P=0.04,OR=0.482,95%CI:0.241-0.966).The number of recurrent tumours and use of other treatment modalities did not affect survival.No survival difference was observed between mTOR inhibitor monotherapy and combination therapy with calcineurin inhibitor.CONCLUSION mTOR inhibitors prolonged survival after post-transplant HCC recurrence.

Evolution of breast cancer therapeutics: Breast tumour kinase's role in breast cancer and hope for breast tumour kinase targeted therapy

There have been significant improvements in the detection and treatment of breast cancer in recent decades. However, there is still a need to develop more effective therapeutic techniques that are patient specific with reduced toxicity leading to further increases in patients' overall survival; the ongoing progress in understanding recurrence, resistant and spread also needs to be maintained. Better understanding of breast cancer pathology, molecular biology and progression as well as identification of some of the underlying factors involved in breast cancer tumourgenesis and metastasis has led to the identification of novel therapeutic targets. Over a number of years interest has risen in breast tumour kinase(Brk) also known as protein tyrosine kinase 6; the research field has grown and Brk has been described as a desirable therapeutic target in relation to tyrosine kinase inhibition as well as disruption of its kinase independent activity. This review will outline the current "state of play" with respect to targeted therapy for breast cancer, as well as discussing Brk's role in the processes underlying tumour development and metas-tasis and its potential as a therapeutic target in breast cancer.

Systemic meta-analysis assessing the short term applicability of early conversion to mammalian target of rapamycin inhibitors in kidney transplant

AIM To consolidate the present evidence of effectiveness in renal functioning and graft survival following early introduction of mammalian target of rapamycin(m TOR) inhibitors with or without calcineurin inhibitors(CNIs) in renal transplant recipients.METHODS We analysed the current literature following PROSPERO approval describing the role of immunosuppressive agent, m TOR inhibitors as an alternative to CNI within six months of renal transplant by searching the Pub Med, EMBASE, Cochrane, Crossref, and Scopus using Me SH terms. RESULTS Six articles of early withdrawal of CNI and introduction of m TOR-inhibitors within six months of renal transplantation were sought. Glomerular filtration rate(GFR) and serum creatinine were significantly better in m TOR inhibitor group with equivalent survival at 12 mo, even though Biopsy Proven Acute rejection was significantly higher in m TOR-inhibitor group. CONCLUSION The evidence reviewed in this meta-analysis suggests that early introduction m TOR-inhibitors substantial CNI minimization. The m TOR inhibitors such as everolimus and sirolimus, due to their complementary mechanism of action and favourable nephrotoxicity profile; better glomerular filtration, lower serum creatinine with equivalent survival. Having said that, due to the higher rejection rate, may influence the use of these regimens to patients with moderate to high immunological risk patients.

Sodium glucose cotransporter-2 inhibitors: Are we targeting old devil with new problems?

Dear editor,The advent of modern molecular mechanism’s approach to disease treatment is highly advancing to mitigate/normalize the symptoms of disease i.e.hyperglycemia by targeting at least eight different pathophysiological approaches popularly known as omnious octet[1].Importantly,type 2 diabetes is a

Hepatitis C virus resistance to new specifically-targeted antiviral therapy: A public health perspective

Until very recently, treatment for chronic hepatitis C virus(HCV) infection has been based on the combination of two non-viral specific drugs: pegylated interferon-α and ribavirin, which is effective in, overall, about 40%-50% of cases. To improve the response to treatment, novel drugs have been designed to specifically block viral proteins. Multiple compounds are under development, and the approval for clinical use of the first of such direct-acting antivirals in 2011(Telaprevir and Boceprevir), represents a milestone in HCV treatment. HCV therapeutics is entering a new expanding era, and a highly-effective cure is envisioned for the first timesince the discovery of the virus in 1989. However, any antiviral treatment may be limited by the capacity of the virus to overcome the selective pressure of new drugs, generating antiviral resistance. Here, we try to provide a basic overview of new treatments, HCV resistance to new antivirals and some considerations derived from a Public Health perspective, using HCV resistance to protease and polymerase inhibitors as examples.

Small molecule inhibitors of RORγt for Th17 regulation in inflammatory and autoimmune diseases

As a ligand-dependent transcription factor,retinoid-associated orphan receptor gt(RORγt)that controls T helper(Th)17 cell differentiation and interleukin(IL)-17 expression plays a critical role in the progression of several inflammatory and autoimmune conditions.An emerging novel approach to the therapy of these diseases thus involves controlling the transcriptional capacity of RORγt to decrease Th17 cell development and IL-17 production.Several RORγt inhibitors including both antagonists and inverse agonists have been discovered to regulate the transcriptional activity of RORγt by binding to orthosteric-or allosteric-binding sites in the ligand-binding domain.Some of small-molecule inhibitors have entered clinical evaluations.Therefore,in current review,the role of RORγt in Th17 regulation and Th17-related inflammatory and autoimmune diseases was highlighted.Notably,the recently developed RORγt inhibitors were summarized,with an emphasis on their optimization from lead compounds,efficacy,toxicity,mechanisms of action,and clinical trials.The limitations of current development in this area were also discussed to facilitate future research.

Discovery of a novel small inhibitor R J19 targeting to human Hsp90

Heat shock protein 90(Hsp90) can promote growth and proliferation of cancer cells by helping in folding, conformational maturation, and activation of various client proteins. Therefore, Hsp90 has been paid more attention to as an anticancer drug target. Reported Hsp90 inhibitors have several limitations such as poor solubility, limited bioavailability, and hepatotoxicity. Here, a novel small inhibitor RJ19 has been designed using fragment-based drug discovery and synthesized. Additionally, a crystal structure of Hsp90 N-RJ19 was determined by X-ray diffraction(resolution limit, 2.0 A, PDB code 4 L90). The crystal structure of Hsp90 N-RJ19 was analyzed in detail and compared with that of native Hsp90 N, Hsp90 N-ATP, and Hsp90 N-GDM,respectively. It was indicated that RJ19 interacted with Hsp90~N at the ATP-binding pocket, which suggests that RJ19 may replace nucleotides to bind with Hsp90~N to result in chaperone function failure of Hsp90. RJ19, therefore, has emerged as a promising anticancer lead compound. Rearrangement and displacement of L2 Loop in Hsp90~N-RJ 19 play a key role in the function failure, which also makes the pocket wider and longer facilitating structure modification of RJ19 later. The complex crystal structure and interaction between RJ19 and Hsp90~N provide a rational basis for the design and optimization of novel anticancer drugs.

Inhibition of FLT3:A Prototype for Molecular Targeted Therapy in Acute Myeloid Leukemia

Modern therapy of acute myeloid leukemia(AML)began in 1973 with the first report of the successful combination of daunorubicin and cytarabine,which led to complete remission in approximately 45%of patients.Accurate AML diagnosis was dependent on morphology,aided initially only by cytochemistry.Unlike acute lymphoblastic leukemia(ALL),immunophenotyping offered little in the diagnosis of AML,at least during the 1970s and 1980s.The advent of reliable cytogenetics changed the entire prognostic outlook of AML.With karyotypic analysis,different groups of AML could be classified and stratified for various therapies.Unique mutational profiling was a major advance in further categorizing AML patients,aided by the immunophenotypic identification of antigenic markers on the cells.All these advances were occurring as the understanding of the importance of the tumor burden—known as minimal residual disease(MRD)—became crucial for the management of AML patients.The efficacy of MRD has rapidly progressed in the past decade,from a specificity of 103 with immunophenotyping to 104 with polymerase chain reaction(PCR),which is only appropriate for some patients with AML,and finally to 105 or even 106 cells with the extraordinary sensitivity of next-generation sequencing(NGS).All of these advances have promoted the concept of personalized medicine,which has led to the advent of targeted agents that can accurately be used for specific diagnostic subtypes.Responses can be predicted and measured accurately.Such targeted agents have now become a cornerstone in the management of AML,increasing effi-cacy and dramatically reducing toxicity.The focus of this review is on one of the most well-studied targeted agents in AML:the FMS-like tyrosine kinase 3(FLT3)inhibitors,which have impacted the prognostication and therapeutics of AML.This review selectively discusses the FLT3 inhibitors in detail,as a model for the other burgeoning targeted agents that have already been approved,as well as those that are currently in development.