Small Molecule Inhibitors For Treatment Research Articles

FTO diversely influences sensitivity of neuroblastoma cells to various chemotherapeutic drugs.

Chemotherapy resistance is a significant factor in treatment failure in patients with neuroblastoma (NB), and it directly affects patient prognosis. Therefore, identifying novel therapeutic targets to enhance chemosensitivity is essential to improve the cure rate and prognosis of patients with NB. In this study, we investigated the role of FTO in chemosensitivity of NB cells to various chemotherapeutic drugs. Our results showed that high FTO expression was positively correlated with increased survival probability and favorable prognostic factors in patients with NB. FTO overexpression inhibited cell proliferation, whereas FTO knockdown promoted cell proliferation in NB cells. FTO expression alteration had contrasting effects on NB cells' sensitivity to etoposide but had no significant impact on sensitivity to cisplatin. Downregulation of FTO reduced the sensitivity of NB cells to paclitaxel, whereas upregulation of FTO enhanced its sensitivity. Additionally, the sensitivities between patients with lower and higher FTO expression to various chemotherapeutic drugs or small-molecule inhibitors were different. Thus, FTO affects the sensitivities of NB cells differently depending on the different chemotherapeutic drugs and small-molecule inhibitors. This finding may guide physicians and patients choose the appropriate chemotherapeutic drugs or small-molecule inhibitors for treatment.

CK1 and PP1 regulate Rift Valley fever virus genome replication through L protein phosphorylation

Rift Valley fever virus (RVFV) is an arbovirus in the Phenuiviridae family identified initially by the large ‘abortion storms’ observed among ruminants; RVFV can also infect humans. In humans, there is a wide variation of clinical symptoms ranging from subclinical to mild febrile illness to hepatitis, retinitis, delayed-onset encephalitis, or even hemorrhagic fever. The RVFV is a tri-segmented negative-sense RNA virus consisting of S, M, and L segments. The L segment encodes the RNA-dependent RNA polymerase (RdRp), termed the L protein, which is responsible for both viral mRNA synthesis and genome replication. Phosphorylation of viral RdRps is known to regulate viral replication. This study shows that RVFV L protein is serine phosphorylated and identified Casein Kinase 1 alpha (CK1α) and protein phosphatase 1 alpha (PP1α) as L protein binding partners. Inhibition of CK1 and PP1 through small molecule inhibitor treatment, D4476 and 1E7-03, respectively, caused a change in the phosphorylated status of the L protein. Inhibition of PP1α resulted in increased L protein phosphorylation whereas inhibition of CK1α decreased L protein phosphorylation. It was also found that in RVFV infected cells, PP1α localized to the cytoplasmic compartment. Treatment of RVFV infected cells with CK1 inhibitors reduced virus production in both mammalian and mosquito cells. Lastly, inhibition of either CK1 or PP1 reduced viral genomic RNA levels. These data indicate that L protein is phosphorylated and that CK1 and PP1 play a crucial role in regulating the L protein phosphorylation cycle, which is critical to viral RNA production and viral replication.

Systematic investigation of chemo-immunotherapy synergism to shift anti-PD-1 resistance in cancer

Chemo-immunotherapy combinations have been regarded as one of the most practical ways to improve immunotherapy response in cancer patients. In this study, we integrate the transcriptomics data from anti-PD-1-treated tumors and compound-treated cancer cell lines to systematically screen for chemo-immunotherapy synergisms in silico. Through analyzing anti-PD-1 induced expression changes in patient tumors, we develop a shift ability score to measure if a chemotherapy or a small molecule inhibitor treatment can shift anti-PD-1 resistance in tumor cells. By applying shift ability analysis to 41,321 compounds and 16,853 shRNA treated cancer cell lines transcriptomic data, we characterize the landscape of chemo-immunotherapy synergism and experimentally validated a mitochondrial RNA-dependent mechanism for drug-induced immune activation in tumor. Our study represents an effort to mechanistically characterize chemo-immunotherapy synergism and will facilitate future pre-clinical and clinical studies.

Perspectives and challenges of small molecule inhibitor therapy for FLT3-mutated acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous clonal disease characterized overall by an aggressive clinical course. The underlying genetic abnormalities present in leukemic cells contribute significantly to the AML phenotype. Mutations in FMS-like tyrosine kinase 3 (FLT3) are one of the most common genetic abnormalities identified in AML, and the presence of these mutations strongly influences disease presentation and negatively impacts prognosis. Since mutations in FLT3 were identified in AML, they have been recognized as a valid therapeutic target resulting in decades of research to develop effective small molecule inhibitor treatment that could improve outcome for these patients. Despite the approval of several FLT3 inhibitors over the last couple of years, the treatment of patients with FLT3-mutated AML remains challenging and many questions still need to be addressed. This review will provide an up-to-date overview of our current understanding of FLT3-mutated AML and discuss what the current status is of the available FLT3 inhibitors for the day-to-day management of this aggressive disease.

Interdependence of SS18-SSX-driven YAP1 and β-Catenin Activation in Synovial Sarcoma.

This study provides deeper insights into synovial sarcoma tumor biology demonstrating a mutual dependence between YAP1/TAZ and β-catenin transcriptional activity and a complex interplay with the SS18-SSX fusion protein within the BAF complex.

Exploring MicroRNA and Exosome Involvement in Malignant Pleural Mesothelioma Drug Response.

Simple SummaryMalignant pleural mesothelioma (MPM) is a deadly thoracic malignancy with limited treatment options. Chemotherapy remains the most widely used first-line treatment for unresectable MPM but is hampered by drug resistance issues. Small molecule inhibitors and microRNA mimics have shown promising potential for the treatment of MPM in preclinical studies, but are yet to be successfully implemented in the clinical setting. Our study aims to provide an understanding of the molecular mechanism(s) that mediate drug response in MPM. The inhibitor of apoptosis family member, survivin, has been reported to be over-expressed in MPM and is associated with drug resistance. Therefore, we particularly focused on determining the cellular mechanism(s) that contribute to MPM cell response to a survivin small molecule inhibitor, YM155. Our study provides key information to facilitate a prediction of the potential utility of small molecule inhibitors and microRNA mimics as treatment options for MPM.Malignant pleural mesothelioma (MPM) is a deadly thoracic malignancy and existing treatment options are limited. Chemotherapy remains the most widely used first-line treatment regimen for patients with unresectable MPM, but is hampered by drug resistance issues. The current study demonstrated a modest enhancement of MPM cell sensitivity to chemotherapy drug treatment following microRNA (miRNA) transfection in MPM cell lines, albeit not for all tested miRNAs. This effect was more pronounced for FAK (PND-1186) small molecule inhibitor treatment; consistent with previously published data. We previously established that MPM response to survivin (YM155) small molecule inhibitor treatment is unrelated to basal survivin expression. Here, we showed that MPM response to YM155 treatment is enhanced following miRNA transfection of YM155-resistant MPM cells. We determined that YM155-resistant MPM cells secrete a higher level of exosomes in comparison to YM155-sensitive MPM cells. Despite this, an exosome inhibitor (GW4896) did not enhance MPM cell sensitivity to YM155. Additionally, our study showed no evidence of a correlation between the mRNA expression of inhibitor of apoptosis (IAP) gene family members and MPM cell sensitivity to YM155. However, two drug transporter genes, ABCA6 and ABCA10, were upregulated in the MPM cell lines and correlated with poor sensitivity to YM155.

Abstract A031: Interplay of YAP1, β-catenin and the SS18-SSX fusion protein in synovial sarcoma

Abstract Introduction: Synovial sarcoma (SySa) is a rare soft-tissue malignancy characterized by a specific chromosomal translocation t(X;18). The resulting chimeric SS18-SSX fusion protein drives SySa pathogenesis by dysregulating gene transcription. As therapeutic targeting of SS18-SSX is notoriously difficult, the identification of SS18-SSX-dependent pathomechanisms may uncover novel molecular vulnerabilities. Since previous functional analyses revealed a connection between SS18-SSX and the activity of the transcriptional co-regulators YAP1/TAZ and β-catenin, this study examined a potential crosstalk between these effectors in SySa. Experimental Procedures: Nuclear abundance of YAP1/TAZ and β-catenin was analyzed by immunohistochemistry in a large cohort of SySa tissue specimens. Two SySa cell lines were employed to modulate YAP1/TAZ/β-catenin transcriptional activity by RNAi-mediated knockdown, small molecule inhibitors, and overexpression vectors in vitro. Changes in transcriptional activity were determined via luciferase reporter assays. As YAP1 and β-catenin showed highest interdependence, co-immunoprecipitation experiments were performed to investigate their interplay with the SS18-SSX fusion protein in SySa cells. Results: Immunohistochemically, a substantial subset of SySa tissue specimens showed concurrent nuclear accumulation of YAP1/TAZ and β-catenin. In vitro, SS18-SSX was found to promote YAP1/TAZ and β-catenin transcriptional activity. RNAi-mediated knockdown of YAP1, TAZ or β-catenin and small molecule inhibitor treatment mutually downregulated TEAD and TCF luciferase reporter activity, while expression of hyperactive variants led to a reciprocal luciferase reporter induction. Finally, co-immunoprecipitation assays demonstrated nuclear co-localization of SS18-SSX with YAP1 and β-catenin in SySa cell lines. Conclusions: This study reveals an interdependency between YAP1 and β-catenin activation and a complex interplay with the SySa-specific SS18-SSX fusion protein. Citation Format: Ilka Isfort, Ruth Berthold, Lorena Heinst, Eva Wardelmann, Marcel Trautmann, Wolfgang Hartmann. Interplay of YAP1, β-catenin and the SS18-SSX fusion protein in synovial sarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A031.

RIP1-dependent Apoptosis and Differentiation Regulated by Skp2 and Akt/GSK3β in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a heterogeneous neoplasm characterized by variations in cytogenetics and molecular abnormalities, which result in variable response to therapy. Receptor-interacting serine/threonine kinase 1 (RIP1)-mediated necroptosis has been reported to have a potential role in the treatment of AML. We obtained Skp2 and RIP1 are significantly overexpressed in AML samples using original published data, and identified that Skp2-depletion in AML cells significantly suppressed RIP1. Functional analysis showed that the inhibition of RIP1 caused by necrostatin-1 (Nec-1) inhibited the proliferation, simultaneously facilitate both the apoptosis and differentiation of AML cells. Mechanistical analysis elucidated that knockdown of Skp2 suppresses RIP1 by transcriptional regulation but not by proteasome degradation. Additionally, Skp2 regulated the function of RIP1 by decreasing K63-linked ubiquitin interaction with RIP1. Moreover, the suppression of Akt/GSK3β was observed in Skp2 knockdown stable NB4 cells. Also, GSK3β inactivation via small-molecule inhibitor treatment remarkably decreased RIP1 level. RIP1 regulates differentiation by interacting with RARα, increasing RA signaling targets gene C/EBPα and C/EBPβ. In conclusion, our study provides a novel insight into the mechanism of tumorigenesis and the development of AML, for which the Skp2-Akt/GSK3β-RIP1 pathway can be developed as a promising therapeutic target.

Specific small-molecule inhibition of PLD1 prevents ADRD-like memory deficits by preserving dendritic spine integrity driven by amyloidogenic proteins.

Phosphatidyl choline phospholipase D (PC-PLD), a lipolytic enzyme that breaks down membrane phospholipids via two isoforms - a constitutively expressed PLD2 and an inducible PLD1 isoform - are also involved in developmentally important signaling mechanisms that regulate synaptic function. We were the first to propose and present a systematic study that established PLD1 as the aberrantly elevated isoform in AD and related dementia using human clinical samples and provided functional proof using mouse models to demonstrate the underlying synaptic dysfunction and memory deficits. Synaptosomal Western blot analysis on 12 month 3xTg-AD mice hippocampi were used to investigate neuronal PLD1 expression and function. Long term potentiation of PLD1 dependent changes using pharmacological approaches in ex vivo slice preparations from wildtype and transgenic mouse models were used to assess synaptic perturbations that were first studied using the novel object recognition memory (NOR) and fear conditioning (FC) paradigms. Chronic PLD1 small molecule inhibitor treatment was assessed to ascertain the efficacy against Aβ and tau-driven AD-like memory deficit progression. Lastly, brain tissues from these animals were subjected to Western Blot analyses, Golgi analysis, immunohistochemical analysis to ascertain the potential signaling mechanism(s) that is/are perturbed/altered by overexpression of PLD1 in such diseased states. Chronic PLD1 inhibition ameliorates the synaptic dysfunction and underlying memory deficits in the 3xTg-AD mouse model by specific action on preserving mushroom spine dendritic spine integrity. Further analysis using Western Blots revealed an underlying mechanism. Using chronic administration of a well-tolerated halopemide derivative of the specific PLD1 isoform inhibitor in the preclinical mouse models of synaptic dysfunction and memory deficits associated with amyloidogenic effects of Aβ and tau, we demonstrated neuroprotective aspects involving changes in the dendritic spine integrity that contributes to the preservation of memory.

USP2 is an SKP2 deubiquitylase that stabilizes both SKP2 and its substrates

The stability of a protein is regulated by a balance between its ubiquitylation and deubiquitylation. S-phase kinase-associated protein 2 (SKP2) is an oncogenic F-box protein that recognizes tumor suppressor substrates for targeted ubiquitylation by the E3 ligase SKP1-Cullin1-F-box and degradation by proteasome. SKP2 is itself ubiquitylated by the E3 ligases APC/CCDH1 and SCFFBXW2, and deubiquitylated by deubiquitylases (DUBs) USP10 and USP13. Given the biological significance of SKP2, it is likely that the other E3s or DUBs may also regulate its stability. Here, we report the identification and characterization of USP2 as a new DUB. We first screened a panel of DUBs and found that both USP2 and USP21 bound to endogenous SKP2, but only USP2 deubiquitylated and stabilized SKP2 protein. USP2 inactivation via siRNA knockdown or small-molecule inhibitor treatment remarkably shortened SKP2 protein half-life by enhancing its ubiquitylation and subsequent degradation. Unexpectedly, USP2-stabilized SKP2 did not destabilize its substrates p21 and p27. Mechanistically, USP2 bound to SKP2 via the leucine-rich repeat substrate-binding domain on SKP2 to disrupt the SKP2-substrate binding, leading to stabilization of both SKP2 and these substrates. Biologically, growth suppression induced by USP2 knockdown or USP2 inhibitor is partially mediated via modulation of SKP2 and its substrates. Our study revealed a new mechanism of the cross-talk among the E3–DUB substrates and its potential implication in targeting the USP2–SKP2 axis for cancer therapy.

DSCAM/PAK1 pathway suppression reverses neurogenesis deficits in iPSC-derived cerebral organoids from patients with Down syndrome.

Down syndrome (DS), caused by trisomy of chromosome 21, occurs in 1 of every 800 live births. Early defects in cortical development likely account for the cognitive impairments in DS, although the underlying molecular mechanism remains elusive. Here, we performed histological assays and unbiased single-cell RNA-Seq (scRNA-Seq) analysis on cerebral organoids derived from 4 euploid cell lines and from induced pluripotent stem cells (iPSCs) from 3 individuals with trisomy 21 to explore cell-type-specific abnormalities associated with DS during early brain development. We found that neurogenesis was significantly affected, given the diminished proliferation and decreased expression of layer II and IV markers in cortical neurons in the subcortical regions; this may have been responsible for the reduced size of the organoids. Furthermore, suppression of the DSCAM/PAK1 pathway, which showed enhanced activity in DS, using CRISPR/Cas9, CRISPR interference (CRISPRi), or small-molecule inhibitor treatment reversed abnormal neurogenesis, thereby increasing the size of organoids derived from DS iPSCs. Our study demonstrates that 3D cortical organoids developed in vitro are a valuable model of DS and provide a direct link between dysregulation of the DSCAM/PAK1 pathway and developmental brain defects in DS.

Checkpoint inhibition through small molecule-induced internalization of programmed death-ligand 1

Programmed death-ligand 1 is a glycoprotein expressed on antigen presenting cells, hepatocytes, and tumors which upon interaction with programmed death-1, results in inhibition of antigen-specific T cell responses. Here, we report a mechanism of inhibiting programmed death-ligand 1 through small molecule-induced dimerization and internalization. This represents a mechanism of checkpoint inhibition, which differentiates from anti-programmed death-ligand 1 antibodies which function through molecular disruption of the programmed death 1 interaction. Testing of programmed death ligand 1 small molecule inhibition in a humanized mouse model of colorectal cancer results in a significant reduction in tumor size and promotes T cell proliferation. In addition, antigen-specific T and B cell responses from patients with chronic hepatitis B infection are significantly elevated upon programmed death ligand 1 small molecule inhibitor treatment. Taken together, these data identify a mechanism of small molecule-induced programmed death ligand 1 internalization with potential therapeutic implications in oncology and chronic viral infections.

Predicting the Molecular Mechanism of EGFR Domain II Dimer Binding Interface by Machine Learning to Identify Potent Small Molecule Inhibitor for Treatment of Cancer.

Epidermal growth factor receptor (EGFR) is a transmembrane druggable target controlling cellular differentiation, proliferation, migration, survival and invasion. EGFR activation mainly occurs by its homo/hetro dimerization molecular phenomenon leading to tumor development and invasion. Several tyrosine kinase based inhibitors were discovered as potent anti-cancer drugs. However, mutations in its kinase domain confer resistance to most of these drugs. To overcome this drug resistance, development of small molecule inhibitors disrupting the EGFR Domain II dimer binding by machine learning methods are promising. Based on this insight, a structure-based drug repurposing strategy was adopted to repurpose the existing FDA approved drugs in blocking the EGFR Domain II mediated dimerization. We identified five best repurposed drug molecules showing good binding affinity at its key arm-cavity dimer interface residues by different machine learning methods. The molecular mechanisms of action of these repurposed drugs were computationally validated by molecular electrostatics potential mapping, point mutations at the dimer arm-cavity binding interface, molecular docking and receptor interaction studies. The present machine learning strategy thus forms the basis of identifying potent and putative small molecule drugs for the treatment of different types of cancer.

Neutralization of B-Cell Activating Factor (BAFF) by Belimumab Reinforces Small Molecule Inhibitor Treatment in Chronic Lymphocytic Leukemia.

The introduction of idelalisib, ibrutinib and venetoclax for treatment of chronic lymphocytic leukemia (CLL) has greatly improved long term survival of patients. However, many patients do not achieve complete remission and suffer from development of resistance upon treatment with these small molecule inhibitors. Here we report that the TNF family member B-cell activating factor (BAFF) mediates resistance of CLL cells to idelalisib, ibrutinib and venetoclax by sustaining survival and preventing apoptosis of the malignant B cells as revealed by analysis of cellular ATP levels and mitochondrial membrane integrity as well as caspase activation, respectively. As BAFF also plays a prominent role in autoimmune diseases, the BAFF-neutralizing antibody belimumab was developed and approved for treatment of systemic lupus erythematosus (SLE). When we employed belimumab in the context of CLL treatment with idelalisib, ibrutinib and venetoclax, BAFF neutralization was found to significantly increase the sensitivity of the leukemic cells to all three small molecule inhibitors. Notably, BAFF neutralization proved to be beneficial independently of clinical stage according to Binet and Rai or IgVH mutational status. Our results identify drug repurposing of belimumab for neutralization of BAFF to complement small molecule inhibitor treatment as a promising therapeutic approach in CLL that is presently undergoing clinical evaluation.

Abstract P5-08-02: PTK6 small molecule inhibitor enhances efficacies of chemotherapy in mesenchymal TNBC

Abstract Background: EMT in cancer promotes resistance to chemotherapy and radiotherapy, as well as immune suppression in the tumor microenvironment. EMT is also associated with enhanced tumor dissemination to other organs. EMT is a dynamic cell re-programming process whereby cancer cells lose epithelial markers and acquire mesenchymal markers, enhanced cell migration, and anoikis resistance. EMT is promoted by transcriptional and epigenetic regulators, as well as by signaling pathways. TNBCType and 101-gene model have identified distinct subsets of TNBC that exhibit mesenchymal gene signatures and phenotypes. This particular subset may be associated with chemotherapy resistance and metastatic recurrence in patients with TNBC. We identified protein tyrosine kinase 6 (PTK6) as a promoter of EMT in mesenchymal TNBC through its ability to prevent degradation of SNAIL, a key EMT transcriptional factor. A higher level of SNAIL expression is associated with poor TNBC patient prognosis. We investigated whether SNAIL suppression and EMT reversal by PTK6 small molecule inhibitor treatment enhance efficacy of chemotherapeutic agents that are part of standard of care treatment for patients with TNBC. Methods: Mesenchymal TNBC cell lines or organoids generated from TNBC PDX tumors were treated with varying concentrations of PTK6 small molecule inhibitor alone or in combination with chemotherapeutic agents in 3D cell cultures. The cell viability was assessed using 3D CellTiter-Glo or alamar blue. The combination Index was calculated to examine potential synergistic effects (CI<1: synergism, CI=1: additive, CI>1: antagonism). The in vivo combination effects of PTK6 inhibitor and paclitaxel were also assessed in two TNBC PDX models. Gene ontology analysis, targeted RT-PCR gene expression profiling and protein array were performed to identify potential mechanisms for chemosensitization effects of PTK6 inhibitor treatment. Results: Pre-treatment with PTK6 inhibitor increases sensitivity to paclitaxel or doxorubicin in 3D matrigel culture of TNBC cell lines, as well as in TNBC PDX organoids. The Combination Index suggested synergies between PTK6 inhibitor and chemotherapy treatment (paclitaxel or doxorubicin). While administration of PTK6 inhibitor or paclitaxel alone only modestly suppressed growth of PDX tumors in vivo, PTK6 inhibitor treatment sensitized tumors to paclitaxel treatment, as evidenced by the dramatic suppression of tumor volume and rate of growth. Gene ontology analysis identified gene sets that are significantly differentially expressed in PTK6 inhibitor-treated TNBC tumors, including extracellular matrix, cell migration, cell cycle and microtubule activity. A targeted RT-PCR profiling and protein array found that PTK6 inhibitor modulates expression of molecules that are associated with chemotherapy resistance and immune regulation; decrease in MMP3, PLEK2, osteopontin, IL-6 and CCL5 and increase in CD40. We are currently investigating whether these changes are dependent on Snail downregulation/EMT reversal caused by PTK6 inhibition. Conclusion: PTK6 inhibition may sensitize TNBC to chemotherapy treatment by suppressing Snail and reversing EMT. We will further validate these effects of PTK6 inhibitor treatment with other chemotherapies and immunotherapies. Citation Format: Ito K, Lee E, Sato K, Byerly JH, Zhu J, Irie HY. PTK6 small molecule inhibitor enhances efficacies of chemotherapy in mesenchymal TNBC [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-08-02.

Abstract 2669: Identification of a novel small-molecule inhibitor for treatment of human colon cancer patients

Abstract As the representative targeted anticancer drug for colon cancer patients, Erbitux is the EGFR targeted therapeutic antibody and used for treatment of KRAS wild-type colon cancer patients. Even some patients with KRas wt gene did not respond to Erbitux. However, there is no treatment available for Erbitux-resistant patient group with KRAS WT gene, which is almost 50% of KRAS WT gene holders. Recently, our team identified Erbitux primary resistant related proteins named as CRG (Cetuximab-Resistant Gene) by array analysis based Erbitux responder or nonresponder colon cancer patients derived tissues and confirmed by in vitro and in vivo assay system. Based on these results, we synthesized a novel series of CRG targeted inhibitor. CRG inhibitor (CRG i;WM compound) is a lead compound for treating colon cancer patients who do not respond to Erbitux and have KRAS wild-type gene. CRG i has potent in vitro enzyme activity and high anticancer activity against various colon cancer cell lines with good selectivity in in vitro and in vivo system. Furthermore, the compound has good potent ADME/Tox. profiles for optimized lead. CRG i also displays strong anticancer effect in in vivo xenograft models and patient-derived xenograft (PDX) models. In addition, CRG i shows promising signs of overcoming Erbitux resistance in CRG knockout cells-derived xenograft model. We continue to discover improved preclinical candidates with better selectivity and ADME/Tox. profiles and validate predictive biomarker in colon cancer patients. In these efforts, we found some compounds with better profiles than CRG i. We are also trying to develop small molecules having highly potent activity against mutant CRG. In conclusion, active CRG is a promising biomarker and target for Erbitux-resistant KRAS wt colon cancer patients. Our compounds can be promising therapeutic agents for Erbitux-resistant KRAS wt colon cancer patients. Citation Format: Chun-Ho Park, Sun-Chul Hur, Joseph Kim, Dae Hee Lee, Yoon Sun Park, Jae-Sik Shin, Seung-Woo Hong, Jai-Hee Moon, Hyojin Kim, So Hee Lee, Hyebin Park, Joonyee Jung, Mi Jin Kim, Sang Soo Park, Jun Ki Hong, Ji Hee Gong, Jieun Kim, Il-Whea Ku, Hyun Ho Lee, Dong-Hoon Jin. Identification of a novel small-molecule inhibitor for treatment of human colon cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2669.

Inactivation of PBX3 and HOXA9 by down-regulating H3K79 methylation represses NPM1-mutated leukemic cell survival.

Acute myeloid leukemia (AML) with an NPM1 mutation (NPMc+) has a distinct gene expression signature and displays molecular abnormalities similar to mixed lineage leukemia (MLL), including aberrant expression of the PBX3 and HOXA gene cluster. However, it is unclear if the aberrant expression of PBX3 and HOXA is essential for the survival of NPM1-mutated leukemic cells.Methods: Using the gene expression profiling of TCGA and E-MTAB-3444 datasets, we screened for high co-expression of PBX3 and HOXA9 in NPMc+ leukemia patients. We performed NPMc+ depletion and overexpression experiments to examine aberrant H3K79 methylation through epigenetic regulation. Through RNA interference technology and small-molecule inhibitor treatment, we evaluated the effect of methyl-modified H3K79 on cell survival and explored the possible underlying mechanism.Results: We showed that NPMc+ increased the expression of PBX3 and HOXA9, which are both poor prognosis indicators in AML. High PBX3 and HOXA9 expression was accompanied by increased dimethylated and trimethylated H3K79 in transgenic murine Lin-Sca-1+c-Kit+ cells and human NPMc+ leukemia cells. Using chromatin immunoprecipitation sequencing (ChIP-seq) assays of NPMc+ cells, we determined that hypermethylated H3K79 was present at the expressed HOXA9 gene but not the PBX3 gene. PBX3 expression was positively regulated by HOXA9, and a reduction in either PBX3 or HOXA9 resulted in NPMc+ cell apoptosis. Importantly, an inhibitor of DOT1L, EPZ5676, effectively and selectively promoted NPMc+ human leukemic cell apoptosis by reducing HOXA9 and PBX3 expression.Conclusion: Our data indicate that NPMc+ leukemic cell survival requires upregulation of PBX3 and HOXA9, and this action can be largely attenuated by a DOT1L inhibitor.

Inhibition of CD40-TRAF6 interactions by the small molecule inhibitor 6877002 reduces neuroinflammation

BackgroundThe influx of leukocytes into the central nervous system (CNS) is a key hallmark of the chronic neuro-inflammatory disease multiple sclerosis (MS). Strategies that aim to inhibit leukocyte migration across the blood-brain barrier (BBB) are therefore regarded as promising therapeutic approaches to combat MS. As the CD40L-CD40 dyad signals via TNF receptor-associated factor 6 (TRAF6) in myeloid cells to induce inflammation and leukocyte trafficking, we explored the hypothesis that specific inhibition of CD40-TRAF6 interactions can ameliorate neuro-inflammation.MethodsHuman monocytes were treated with a small molecule inhibitor (SMI) of CD40-TRAF6 interactions (6877002), and migration capacity across human brain endothelial cells was measured. To test the therapeutic potential of the CD40-TRAF6-blocking SMI under neuro-inflammatory conditions in vivo, Lewis rats and C57BL/6J mice were subjected to acute experimental autoimmune encephalomyelitis (EAE) and treated with SMI 6877002 for 6 days (rats) or 3 weeks (mice).ResultsWe here show that a SMI of CD40-TRAF6 interactions (6877002) strongly and dose-dependently reduces trans-endothelial migration of human monocytes. Moreover, upon SMI treatment, monocytes displayed a decreased production of ROS, tumor necrosis factor (TNF), and interleukin (IL)-6, whereas the production of the anti-inflammatory cytokine IL-10 was increased. Disease severity of EAE was reduced upon SMI treatment in rats, but not in mice. However, a significant reduction in monocyte-derived macrophages, but not in T cells, that had infiltrated the CNS was eminent in both models.ConclusionsTogether, our results indicate that SMI-mediated inhibition of the CD40-TRAF6 pathway skews human monocytes towards anti-inflammatory cells with reduced trans-endothelial migration capacity, and is able to reduce CNS-infiltrated monocyte-derived macrophages during neuro-inflammation, but minimally ameliorates EAE disease severity. We therefore conclude that SMI-mediated inhibition of the CD40-TRAF6 pathway may represent a beneficial treatment strategy to reduce monocyte recruitment and macrophage activation in the CNS and has the potential to be used as a co-treatment to combat MS.

Regioselective synthesis and biological studies of novel 1-aryl-3, 5-bis (het) aryl pyrazole derivatives as potential antiproliferative agents.

Pyrazole moiety represents an important category of heterocyclic compound in pharmaceutical and medicinal chemistry. The novel 1-aryl-3, 5-bis (het) aryl pyrazole derivatives were synthesized with complementary regioselectivity. The chemical structures were confirmed by IR, 1H NMR, 13C NMR, and mass spectral analysis. The chemical entities were screened in various cancer cell lines to assess their cell viability activity. Results showed that the compound 3-(1-(4-bromophenyl)-5-phenyl-1H-pyrazol-3-yl) pyridine (5d) possessed maximum cytotoxic effect against breast cancer and leukemic cells. The cytotoxicity was confirmed by live-dead cell assay and cell cycle analysis. Mitochondrial membrane potential, Annexin V-FITC staining, DNA fragmentation, Hoechst staining, and western blot assays revealed the ability of compound 5d to induce cell death by activating apoptosis in cancer cells. Thus, the present study demonstrates that compound 5d could be an attractive chemical entity for the development of small molecule inhibitors for treatment of leukemia and breast cancer.

Aspartate β-hydroxylase modulates cellular senescence through glycogen synthase kinase 3β in hepatocellular carcinoma.

Aspartate β-hydroxylase (ASPH) is an enzyme overexpressed in human hepatocellular carcinoma (HCC) tumors that participates in the malignant transformation process. We determined if ASPH was a therapeutic target by exerting effects on cellular senescence to retard HCC progression. ASPH knockdown or knockout was achieved by short hairpin RNAs or the CRISPR/Cas9 system, respectively, whereas enzymatic inhibition was rendered by a potent second-generation small molecule inhibitor of ASPH. Alterations of cell proliferation, colony formation, and cellular senescence were evaluated in human HCC cell lines. The potential mechanisms for activating cellular senescence were explored using murine subcutaneous and orthotopic xenograft models. Inhibition of ASPH expression and enzymatic activity significantly reduced cell proliferation and colony formation but induced tumor cell senescence. Following inhibition of ASPH activity, phosphorylation of glycogen synthase kinase 3β and p16 expression were increased to promote senescence, whereas cyclin D1 and proliferating cell nuclear antigen were decreased to reduce cell proliferation. The mechanisms involved demonstrate that ASPH binds to glycogen synthase kinase 3β and inhibits its subsequent interactions with protein kinase B and p38 upstream kinases as shown by coimmunoprecipitation. In vivo experiments demonstrated that small molecule inhibitor treatment of HCC bearing mice resulted in significant dose-dependent reduced tumor growth, induced phosphorylation of glycogen synthase kinase 3β, enhanced p16 expression in tumor cells, and promoted cellular senescence. We have identified a new mechanism that promotes HCC growth and progression by modulating senescence of tumor cells; these findings suggest that ASPH enzymatic activity is a novel therapeutic target for HCC.