Publications by authors named "Harshani R Lawrence"

52 Publications

Pacritinib Combined with Sirolimus and Low-Dose Tacrolimus for GVHD Prevention after Allogeneic Hematopoietic Cell Transplantation: Preclinical and Phase I Trial Results.

Clin Cancer Res 2021 May 22;27(10):2712-2722. Epub 2021 Mar 22.

Division of Hematology, Oncology, and Transplantation, Department of Medicine, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.

Purpose: In this first-in-human, phase I, GVHD prevention trial (NCT02891603), we combine pacritinib (PAC), a JAK2 inhibitor, with sirolimus to concurrently reduce T-cell costimulation via mTOR and IL6 activity. We evaluate the safety of pacritinib when administered with sirolimus plus low-dose tacrolimus (PAC/SIR/TAC) after allogeneic hematopoietic cell transplantation.

Patients And Methods: The preclinical efficacy and immune modulation of PAC/SIR were investigated in xenogeneic GVHD. Our phase I trial followed a 3+3 dose-escalation design, including dose level 1 (pacritinib 100 mg daily), level 2 (pacritinib 100 mg twice daily), and level 3 (pacritinib 200 mg twice daily). The primary endpoint was to identify the lowest biologically active and safe dose of pacritinib with SIR/TAC ( = 12). Acute GVHD was scored through day +100. Allografts included 8/8 HLA-matched related or unrelated donor peripheral blood stem cells.

Results: In mice, we show that dual JAK2/mTOR inhibition significantly reduces xenogeneic GVHD and increases peripheral regulatory T cell (Treg) potency as well as Treg induction from conventional CD4 T cells. Pacritinib 100 mg twice a day was identified as the minimum biologically active and safe dose for further study. JAK2/mTOR inhibition suppresses pathogenic Th1 and Th17 cells, spares Tregs and antileukemia effector cells, and exhibits preliminary activity in preventing GVHD. PAC/SIR/TAC preserves donor cytomegalovirus (CMV) immunity and permits timely engraftment without cytopenias.

Conclusions: We demonstrate that PAC/SIR/TAC is safe and preliminarily limits acute GVHD, preserves donor CMV immunity, and permits timely engraftment. The efficacy of PAC/SIR/TAC will be tested in our ongoing phase II GVHD prevention trial.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-4725DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8127396PMC
May 2021

Structural Insights into JAK2 Inhibition by Ruxolitinib, Fedratinib, and Derivatives Thereof.

J Med Chem 2021 02 11;64(4):2228-2241. Epub 2021 Feb 11.

Drug Discovery DepartmentMoffitt Cancer Center, Tampa, Florida 33612, United States.

The discovery that aberrant activity of Janus kinase 2 (JAK2) is a driver of myeloproliferative neoplasms (MPNs) has led to significant efforts to develop small molecule inhibitors for this patient population. Ruxolitinib and fedratinib have been approved for use in MPN patients, while baricitinib, an achiral analogue of ruxolitinib, has been approved for rheumatoid arthritis. However, structural information on the interaction of these therapeutics with JAK2 remains unknown. Here, we describe a new methodology for the large-scale production of JAK2 from mammalian cells, which enabled us to determine the first crystal structures of JAK2 bound to these drugs and derivatives thereof. Along with biochemical and cellular data, the results provide a comprehensive view of the shape complementarity required for chiral and achiral inhibitors to achieve highest activity, which may facilitate the development of more effective JAK2 inhibitors as therapeutics.
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http://dx.doi.org/10.1021/acs.jmedchem.0c01952DOI Listing
February 2021

Mesenchymal stem cell-derived interleukin-28 drives the selection of apoptosis resistant bone metastatic prostate cancer.

Nat Commun 2021 02 1;12(1):723. Epub 2021 Feb 1.

Tumor Biology Department, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA.

Bone metastatic prostate cancer (PCa) promotes mesenchymal stem cell (MSC) recruitment and their differentiation into osteoblasts. However, the effects of bone-marrow derived MSCs on PCa cells are less explored. Here, we report MSC-derived interleukin-28 (IL-28) triggers prostate cancer cell apoptosis via IL-28 receptor alpha (IL-28Rα)-STAT1 signaling. However, chronic exposure to MSCs drives the selection of prostate cancer cells that are resistant to IL-28-induced apoptosis and therapeutics such as docetaxel. Further, MSC-selected/IL-28-resistant prostate cancer cells grow at accelerated rates in bone. Acquired resistance to apoptosis is PCa cell intrinsic, and is associated with a shift in IL-28Rα signaling via STAT1 to STAT3. Notably, STAT3 ablation or inhibition impairs MSC-selected prostate cancer cell growth and survival. Thus, bone marrow MSCs drive the emergence of therapy-resistant bone metastatic prostate cancer yet this can be disabled by targeting STAT3.
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http://dx.doi.org/10.1038/s41467-021-20962-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7851397PMC
February 2021

Inhibition of p53 DNA binding by a small molecule protects mice from radiation toxicity.

Oncogene 2020 07 17;39(29):5187-5200. Epub 2020 Jun 17.

Department of Molecular Oncology, Moffitt Cancer Center, Tampa, FL, USA.

Transcription factors are attractive therapeutic targets that are considered non-druggable because they do not have binding sites for small drug-like ligands. We established a cell-free high-throughput screening assay to search for small molecule inhibitors of DNA binding by transcription factors. A screen was performed using p53 as a target, resulting in the identification of NSC194598 that inhibits p53 sequence-specific DNA binding in vitro (IC = 180 nM) and in vivo. NSC194598 selectively inhibited DNA binding by p53 and homologs p63/p73, but did not affect E2F1, TCF1, and c-Myc. Treatment of cells with NSC194598 alone paradoxically led to p53 accumulation and modest increase of transcriptional output owing to disruption of the MDM2-negative feedback loop. When p53 was stabilized and activated by irradiation or chemotherapy drug treatment, NSC194598 inhibited p53 DNA binding and induction of target genes. A single dose of NSC194598 increased the survival of mice after irradiation. The results suggest DNA binding by p53 can be targeted using small molecules to reduce acute toxicity to normal tissues by radiation and chemotherapy.
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http://dx.doi.org/10.1038/s41388-020-1344-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7398576PMC
July 2020

Cereblon harnesses Myc-dependent bioenergetics and activity of CD8+ T lymphocytes.

Blood 2020 08;136(7):857-870

Department of Tumor Biology, Moffitt Cancer Center and Research Institute, Tampa, FL.

Immunomodulatory drugs, such as thalidomide and related compounds, potentiate T-cell effector functions. Cereblon (CRBN), a substrate receptor of the DDB1-cullin-RING E3 ubiquitin ligase complex, is the only molecular target for this drug class, where drug-induced, ubiquitin-dependent degradation of known "neosubstrates," such as IKAROS, AIOLOS, and CK1α, accounts for their biological activity. Far less clear is whether these CRBN E3 ligase-modulating compounds disrupt the endogenous functions of CRBN. We report that CRBN functions in a feedback loop that harnesses antigen-specific CD8+ T-cell effector responses. Specifically, Crbn deficiency in murine CD8+ T cells augments their central metabolism manifested as elevated bioenergetics, with supraphysiological levels of polyamines, secondary to enhanced glucose and amino acid transport, and with increased expression of metabolic enzymes, including the polyamine biosynthetic enzyme ornithine decarboxylase. Treatment with CRBN-modulating compounds similarly augments central metabolism of human CD8+ T cells. Notably, the metabolic control of CD8+ T cells by modulating compounds or Crbn deficiency is linked to increased and sustained expression of the master metabolic regulator MYC. Finally, Crbn-deficient T cells have augmented antigen-specific cytolytic activity vs melanoma tumor cells, ex vivo and in vivo, and drive accelerated and highly aggressive graft-versus-host disease. Therefore, CRBN functions to harness the activation of CD8+ T cells, and this phenotype can be exploited by treatment with drugs.
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http://dx.doi.org/10.1182/blood.2019003257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7426646PMC
August 2020

Metabolic reprogramming augments potency of human pSTAT3-inhibited iTregs to suppress alloreactivity.

JCI Insight 2020 05 7;5(9). Epub 2020 May 7.

Division of Hematology, Oncology, and Transplantation, Department of Medicine, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA.

Immunosuppressive donor Tregs can prevent graft-versus-host disease (GVHD) or solid-organ allograft rejection. We previously demonstrated that inhibiting STAT3 phosphorylation (pSTAT3) augments FOXP3 expression, stabilizing induced Tregs (iTregs). Here we report that human pSTAT3-inhibited iTregs prevent human skin graft rejection and xenogeneic GVHD yet spare donor antileukemia immunity. pSTAT3-inhibited iTregs express increased levels of skin-homing cutaneous lymphocyte-associated antigen, immunosuppressive GARP and PD-1, and IL-9 that supports tolerizing mast cells. Further, pSTAT3-inhibited iTregs significantly reduced alloreactive conventional T cells, Th1, and Th17 cells implicated in GVHD and tissue rejection and impaired infiltration by pathogenic Th2 cells. Mechanistically, pSTAT3 inhibition of iTregs provoked a shift in metabolism from oxidative phosphorylation (OxPhos) to glycolysis and reduced electron transport chain activity. Strikingly, cotreatment with coenzyme Q10 restored OxPhos in pSTAT3-inhibited iTregs and augmented their suppressive potency. These findings support the rationale for clinically testing the safety and efficacy of metabolically tuned, human pSTAT3-inhibited iTregs to control alloreactive T cells.
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http://dx.doi.org/10.1172/jci.insight.136437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7253027PMC
May 2020

Divergent Polypharmacology-Driven Cellular Activity of Structurally Similar Multi-Kinase Inhibitors through Cumulative Effects on Individual Targets.

Cell Chem Biol 2019 09 27;26(9):1240-1252.e11. Epub 2019 Jun 27.

Department of Drug Discovery, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL 33612, USA; Department of Oncologic Sciences, University of South Florida, Tampa, FL 33620, USA. Electronic address:

Despite recent successes of precision and immunotherapies there is a persisting need for novel targeted or multi-targeted approaches in complex diseases. Through a systems pharmacology approach, including phenotypic screening, chemical and phosphoproteomics, and RNA-seq, we elucidated the targets and mechanisms underlying the differential anticancer activity of two structurally related multi-kinase inhibitors, foretinib, and cabozantinib, in lung cancer cells. Biochemical and cellular target validation using probe molecules and RNAi revealed a polypharmacology mechanism involving MEK1/2, FER, and AURKB, which were each more potently inhibited by foretinib than cabozantinib. Based on this, we developed a synergistic combination of foretinib with barasertib, a more potent AURKB inhibitor, for MYC-amplified small-cell lung cancer. This systems pharmacology approach showed that small structural changes of drugs can cumulatively, through multiple targets, result in pronounced anticancer activity differences and that detailed mechanistic understanding of polypharmacology can enable repurposing opportunities for cancers with unmet medical need.
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http://dx.doi.org/10.1016/j.chembiol.2019.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6754293PMC
September 2019

Dual Farnesyl and Geranylgeranyl Transferase Inhibitor Thwarts Mutant KRAS-Driven Patient-Derived Pancreatic Tumors.

Clin Cancer Res 2019 10 21;25(19):5984-5996. Epub 2019 Jun 21.

Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida.

Purpose: Mutant KRAS is a major driver of pancreatic oncogenesis and therapy resistance, yet KRAS inhibitors are lacking in the clinic. KRAS requires farnesylation for membrane localization and cancer-causing activity prompting the development of farnesyltransferase inhibitors (FTIs) as anticancer agents. However, KRAS becomes geranylgeranylated and active when cancer cells are treated with FTIs. To overcome this geranylgeranylation-dependent resistance to FTIs, we designed FGTI-2734, a RAS C-terminal mimetic dual FT and geranylgeranyltransferase-1 inhibitor (GGTI).

Experimental Design: Immunofluorescence, cellular fractionation, and gel shift assays were used to assess RAS membrane association, Western blotting to evaluate FGTI-2734 effects on signaling, and mouse models to demonstrate its antitumor activity.

Results: FGTI-2734, but not the selective FTI-2148 and GGTI-2418, inhibited membrane localization of KRAS in pancreatic, lung, and colon human cancer cells. FGTI-2734 induced apoptosis and inhibited the growth in mice of mutant KRAS-dependent but not mutant KRAS-independent human tumors. Importantly, FGTI-2734 inhibited the growth of xenografts derived from four patients with pancreatic cancer with mutant KRAS (2 G12D and 2 G12V) tumors. FGTI-2734 was also highly effective at inhibiting, in three-dimensional cocultures with resistance promoting pancreatic stellate cells, the viability of primary and metastatic mutant KRAS tumor cells derived from eight patients with pancreatic cancer. Finally, FGTI-2734 suppressed oncogenic pathways mediated by AKT, mTOR, and cMYC while upregulating p53 and inducing apoptosis in patient-derived xenografts .

Conclusions: The development of this novel dual FGTI overcomes a major hurdle in KRAS resistance, thwarting growth of patient-derived mutant KRAS-driven xenografts from patients with pancreatic cancer, and as such it warrants further preclinical and clinical studies.
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http://dx.doi.org/10.1158/1078-0432.CCR-18-3399DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6774803PMC
October 2019

Fendiline Enhances the Cytotoxic Effects of Therapeutic Agents on PDAC Cells by Inhibiting Tumor-Promoting Signaling Events: A Potential Strategy to Combat PDAC.

Int J Mol Sci 2019 May 16;20(10). Epub 2019 May 16.

Department of Molecular Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA.

The L-type calcium channel blocker fendiline has been shown to interfere with Ras-dependent signaling in K-Ras mutant cancer cells. Earlier studies from our lab had shown that treatment of pancreatic cancer cells with fendiline causes significant cytotoxicity and interferes with proliferation, survival, migration, invasion and anchorage independent growth. Currently there are no effective therapies to manage PDACs. As fendiline has been approved for treatment of patients with angina, we hypothesized that, if proven effective, combinatorial therapies using this agent would be easily translatable to clinic for testing in PDAC patients. Here we tested combinations of fendiline with gemcitabine, visudyne (a YAP1 inhibitor) or tivantinib (ARQ197, a c-Met inhibitor) for their effectiveness in overcoming growth and oncogenic characteristics of PDAC cells. The Hippo pathway component YAP1 has been shown to bypass K-Ras addiction, and allow tumor growth, in a Ras-null mouse model. Similarly, c-Met expression has been associated with poor prognosis and metastasis in PDAC patients. Our results presented here show that combinations of fendiline with these inhibitors show enhanced anti-tumor activity in Panc1, MiaPaCa2 and CD18/HPAF PDAC cells, as evident from the reduced viability, migration, anchorage-independent growth and self-renewal. Biochemical analysis shows that these agents interfere with various signaling cascades such as the activation of Akt and ERK, as well as the expression of c-Myc and CD44 that are altered in PDACs. These results imply that inclusion of fendiline may improve the efficacy of various chemotherapeutic agents that could potentially benefit PDAC patients.
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http://dx.doi.org/10.3390/ijms20102423DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6567171PMC
May 2019

GSK3 suppression upregulates β-catenin and c-Myc to abrogate KRas-dependent tumors.

Nat Commun 2018 12 4;9(1):5154. Epub 2018 Dec 4.

Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.

Mutant KRas is a significant driver of human oncogenesis and confers resistance to therapy, underscoring the need to develop approaches that disable mutant KRas-driven tumors. Because targeting KRas directly has proven difficult, identifying vulnerabilities specific for mutant KRas tumors is an important alternative approach. Here we show that glycogen synthase kinase 3 (GSK3) is required for the in vitro and in vivo growth and survival of human mutant KRas-dependent tumors but is dispensable for mutant KRas-independent tumors. Further, inhibiting phosphorylation of GSK3 substrates c-Myc on T58 and β-catenin on S33/S37/T41 and their subsequent upregulation contribute to the antitumor activity of GSK3 inhibition. Importantly, GSK3 blockade inhibits the in vivo growth of G12D, G12V, and G12C mutant KRas primary and metastatic patient-derived xenografts from pancreatic cancer patients who progressed on chemo- and radiation therapies. This discovery opens new avenues to target mutant KRas-dependent cancers.
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http://dx.doi.org/10.1038/s41467-018-07644-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279809PMC
December 2018

Targeting the BRD4-HOXB13 Coregulated Transcriptional Networks with Bromodomain-Kinase Inhibitors to Suppress Metastatic Castration-Resistant Prostate Cancer.

Mol Cancer Ther 2018 12 21;17(12):2796-2810. Epub 2018 Sep 21.

Tumor Biology Department, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida.

Resistance to androgen receptor (AR) antagonists is a significant problem in the treatment of castration-resistant prostate cancers (CRPC). Identification of the mechanisms by which CRPCs evade androgen deprivation therapies (ADT) is critical to develop novel therapeutics. We uncovered that CRPCs rely on BRD4-HOXB13 epigenetic reprogramming for androgen-independent cell proliferation. Mechanistically, BRD4, a member of the BET bromodomain family, epigenetically promotes HOXB13 expression. Consistently, genetic disruption of or pharmacological suppression of its mRNA and protein expression by the novel dual-activity BET bromodomain-kinase inhibitors directly correlates with rapid induction of apoptosis, potent inhibition of tumor cell proliferation and cell migration, and suppression of CRPC growth. Integrative analysis revealed that the BRD4-HOXB13 transcriptome comprises a proliferative gene network implicated in cell-cycle progression, nucleotide metabolism, and chromatin assembly. Notably, although the core HOXB13 target genes responsive to BET inhibitors (HOTBIN10) are overexpressed in metastatic cases, in ADT-treated CRPC cell lines and patient-derived circulating tumor cells (CTC) they are insensitive to AR depletion or blockade. Among the HOTBIN10 genes, AURKB and MELK expression correlates with HOXB13 expression in CTCs of mCRPC patients who did not respond to abiraterone (ABR), suggesting that AURKB inhibitors could be used additionally against high-risk HOXB13-positive metastatic prostate cancers. Combined, our study demonstrates that BRD4-HOXB13-HOTBIN10 regulatory circuit maintains the malignant state of CRPCs and identifies a core proproliferative network driving ADT resistance that is targetable with potent dual-activity bromodomain-kinase inhibitors.
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http://dx.doi.org/10.1158/1535-7163.MCT-18-0602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6528782PMC
December 2018

Ligand-mediated protein degradation reveals functional conservation among sequence variants of the CUL4-type E3 ligase substrate receptor cereblon.

J Biol Chem 2018 04 15;293(16):6187-6200. Epub 2018 Feb 15.

From the Department of Immunology,

Upon binding to thalidomide and other immunomodulatory drugs, the E3 ligase substrate receptor cereblon (CRBN) promotes proteosomal destruction by engaging the DDB1-CUL4A-Roc1-RBX1 E3 ubiquitin ligase in human cells but not in mouse cells, suggesting that sequence variations in CRBN may cause its inactivation. Therapeutically, CRBN engagers have the potential for broad applications in cancer and immune therapy by specifically reducing protein expression through targeted ubiquitin-mediated degradation. To examine the effects of defined sequence changes on CRBN's activity, we performed a comprehensive study using complementary theoretical, biophysical, and biological assays aimed at understanding CRBN's nonprimate sequence variations. With a series of recombinant thalidomide-binding domain (TBD) proteins, we show that CRBN sequence variants retain their drug-binding properties to both classical immunomodulatory drugs and dBET1, a chemical compound and targeting ligand designed to degrade bromodomain-containing 4 (BRD4) via a CRBN-dependent mechanism. We further show that dBET1 stimulates CRBN's E3 ubiquitin-conjugating function and degrades BRD4 in both mouse and human cells. This insight paves the way for studies of CRBN-dependent proteasome-targeting molecules in nonprimate models and provides a new understanding of CRBN's substrate-recruiting function.
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http://dx.doi.org/10.1074/jbc.M117.816868DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5912449PMC
April 2018

Blockade of ACK1/TNK2 To Squelch the Survival of Prostate Cancer Stem-like Cells.

Sci Rep 2018 01 31;8(1):1954. Epub 2018 Jan 31.

Tumor Biology Department, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA.

Prostate cancer stem-like cells (PCSCs) are not only enriched in the CD44PSA subpopulation but also employ androgen-independent signaling mechanisms for survival. CD44 PCSCs defy androgen deprivation, resist chemo- and radiotherapy and are highly tumorigenic. Human prostate tissue microarray (TMA) staining revealed an increased membranous staining of CD44 in the luminal compartment in higher grade G7-G9 tumors versus staining of the basal layer in benign hyperplasia. To uncover tyrosine kinase/s critical for the survival of the CD44PSA subpopulation, we performed an unbiased screen targeting 87 tyrosine kinases with gene specific siRNAs. Among a subset of tyrosine kinases crucial for PCSC survival, was a non-receptor tyrosine kinase, ACK1/TNK2, a critical regulator of castration resistant prostate cancer (CRPC) growth. Consistently, activated ACK1 as measured by phosphorylation at Tyr284 was significant in the CD44PSA population. Conversely, pharmacological inhibition by ACK1 inhibitor, (R)-9bMS mitigated CD44PSA sphere formation, overcame resistance to radiation-induced cell death, induced significant apoptosis in PCSCs and inhibited CD44PSA xenograft tumor growth in castrated mice suggesting dependency of PCSCs on ACK1 for survival. Thus, blockade of ACK1/TNK2 could be a new therapeutic modality to target recalcitrant PCSCs.
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http://dx.doi.org/10.1038/s41598-018-20172-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5792546PMC
January 2018

Dabrafenib inhibits the growth of BRAF-WT cancers through CDK16 and NEK9 inhibition.

Mol Oncol 2018 01 23;12(1):74-88. Epub 2017 Nov 23.

The Department of Tumor Biology, The Moffitt Cancer Center & Research Institute, Tampa, FL, USA.

Although the BRAF inhibitors dabrafenib and vemurafenib have both proven successful against BRAF-mutant melanoma, there seem to be differences in their mechanisms of action. Here, we show that dabrafenib is more effective at inhibiting the growth of NRAS-mutant and KRAS-mutant cancer cell lines than vemurafenib. Using mass spectrometry-based chemical proteomics, we identified NEK9 and CDK16 as unique targets of dabrafenib. Both NEK9 and CDK16 were highly expressed in specimens of advanced melanoma, with high expression of both proteins correlating with a worse overall survival. A role for NEK9 in the growth of NRAS- and KRAS-mutant cell lines was suggested by siRNA studies in which silencing was associated with decreased proliferation, cell cycle arrest associated with increased p21 expression, inhibition of phospho-CHK1, decreased CDK4 expression, and the initiation of a senescence response. Inhibition of CDK4 but not CHK1 recapitulated the effects of NEK9 silencing, indicating this to be the likely mechanism of growth inhibition. We next turned our attention to CDK16 and found that its knockdown inhibited the phosphorylation of the Rb protein at S780 and increased expression of p27. Both of these effects were phenocopied in NRAS- and KRAS-mutant cancer cells by dabrafenib, but not vemurafenib. Combined silencing of NEK9 and CDK16 was associated with enhanced inhibition of melanoma cell proliferation. In summary, we have identified dabrafenib as a potent inhibitor of NEK9 and CDK16, and our studies suggest that inhibition of these kinases may have activity against cancers that do not harbor BRAF mutations.
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http://dx.doi.org/10.1002/1878-0261.12152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5748485PMC
January 2018

ACK1/TNK2 Regulates Histone H4 Tyr88-phosphorylation and AR Gene Expression in Castration-Resistant Prostate Cancer.

Cancer Cell 2017 06;31(6):790-803.e8

Drug Discovery Department, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, USA; Department of Oncological Sciences, University of South Florida, Tampa, FL 33612, USA. Electronic address:

The androgen receptor (AR) is critical for the progression of prostate cancer to a castration-resistant (CRPC) state. AR antagonists are ineffective due to their inability to repress the expression of AR or its splice variant, AR-V7. Here, we report that the tyrosine kinase ACK1 (TNK2) phosphorylates histone H4 at tyrosine 88 upstream of the AR transcription start site. The WDR5/MLL2 complex reads the H4-Y88-phosphorylation marks and deposits the transcriptionally activating H3K4-trimethyl marks promoting AR transcription. Reversal of the pY88-H4 epigenetic marks by the ACK1 inhibitor (R)-9bMS-sensitized naive and enzalutamide-resistant prostate cancer cells and reduced AR and AR-V7 levels to mitigate CRPC tumor growth. Thus, a feedforward ACK1/pY88-H4/WDR5/MLL2/AR epigenetic circuit drives CRPC and is necessary for maintenance of the malignant state.
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http://dx.doi.org/10.1016/j.ccell.2017.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5512571PMC
June 2017

Dual Targeting of WEE1 and PLK1 by AZD1775 Elicits Single Agent Cellular Anticancer Activity.

ACS Chem Biol 2017 07 7;12(7):1883-1892. Epub 2017 Jun 7.

Drug Discovery Department, H. Lee Moffitt Cancer Center & Research Institute , Tampa, Florida 33612, United States.

Inhibition of the WEE1 tyrosine kinase enhances anticancer chemotherapy efficacy. Accordingly, the WEE1 inhibitor AZD1775 (previously MK-1775) is currently under evaluation in clinical trials for cancer in combination with chemotherapy. AZD1775 has been reported to display high selectivity and is therefore used in many studies as a probe to interrogate WEE1 biology. However, AZD1775 also exhibits anticancer activity as a single agent although the underlying mechanism is not fully understood. Using a chemical proteomics approach, we here describe a proteome-wide survey of AZD1775 targets in lung cancer cells and identify several previously unknown targets in addition to WEE1. In particular, we observed polo-like kinase 1 (PLK1) as a new target of AZD1775. Importantly, in vitro kinase assays showed PLK1 and WEE1 to be inhibited by AZD1775 with similar potency. Subsequent loss-of-function experiments using RNAi for WEE1 and PLK1 suggested that targeting PLK1 enhances the pro-apoptotic and antiproliferative effects observed with WEE1 knockdown. Combination of RNAi with AZD1775 treatment suggested WEE1 and PLK1 to be the most relevant targets for mediating AZD1775's anticancer effects. Furthermore, disruption of WEE1 by CRISPR-Cas9 sensitized H322 lung cancer cells to AZD1775 to a similar extent as the potent PLK1 inhibitor BI-2536 suggesting a complex crosstalk between PLK1 and WEE1. In summary, we show that AZD1775 is a potent dual WEE1 and PLK1 inhibitor, which limits its use as a specific molecular probe for WEE1. However, PLK1 inhibition makes important contributions to the single agent mechanism of action of AZD1775 and enhances its anticancer effects.
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http://dx.doi.org/10.1021/acschembio.7b00147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5551971PMC
July 2017

Potent Dual BET Bromodomain-Kinase Inhibitors as Value-Added Multitargeted Chemical Probes and Cancer Therapeutics.

Mol Cancer Ther 2017 06 23;16(6):1054-1067. Epub 2017 Mar 23.

Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida.

Synergistic action of kinase and BET bromodomain inhibitors in cell killing has been reported for a variety of cancers. Using the chemical scaffold of the JAK2 inhibitor TG101348, we developed and characterized single agents which potently and simultaneously inhibit BRD4 and a specific set of oncogenic tyrosine kinases including JAK2, FLT3, RET, and ROS1. Lead compounds showed on-target inhibition in several blood cancer cell lines and were highly efficacious at inhibiting the growth of hematopoietic progenitor cells from patients with myeloproliferative neoplasm. Screening across 931 cancer cell lines revealed differential growth inhibitory potential with highest activity against bone and blood cancers and greatly enhanced activity over the single BET inhibitor JQ1. Gene drug sensitivity analyses and drug combination studies indicate synergism of BRD4 and kinase inhibition as a plausible reason for the superior potency in cell killing. Combined, our findings indicate promising potential of these agents as novel chemical probes and cancer therapeutics. .
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http://dx.doi.org/10.1158/1535-7163.MCT-16-0568-TDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5457702PMC
June 2017

Targeting Aurora kinase A and JAK2 prevents GVHD while maintaining Treg and antitumor CTL function.

Sci Transl Med 2017 01;9(372)

Department of Blood and Marrow Transplantation, Moffitt Cancer Center, Tampa, FL 33612, USA.

Graft-versus-host disease (GVHD) is a leading cause of nonrelapse mortality after allogeneic hematopoietic cell transplantation. T cell costimulation by CD28 contributes to GVHD, but prevention is incomplete when targeting CD28, downstream mammalian target of rapamycin (mTOR), or Aurora A. Likewise, interleukin-6 (IL-6)-mediated Janus kinase 2 (JAK2) signaling promotes alloreactivity, yet JAK2 inhibition does not eliminate GVHD. We provide evidence that blocking Aurora A and JAK2 in human T cells is synergistic in vitro, prevents xenogeneic GVHD, and maintains antitumor responses by cytotoxic T lymphocytes (CTLs). Aurora A/JAK2 inhibition is immunosuppressive but permits the differentiation of inducible regulatory T cells (iT) that are hyperfunctional and CD39 bright and efficiently scavenge adenosine triphosphate (ATP). Increased iT potency is primarily a function of Aurora A blockade, whereas JAK2 inhibition suppresses T helper 17 (T17) differentiation. Inhibiting either Aurora A or JAK2 significantly suppresses T1 T cells. However, CTL generated in vivo retains tumor-specific killing despite Aurora A/JAK2 blockade. Thus, inhibiting CD28 and IL-6 signal transduction pathways in donor T cells can increase the T/T ratio, prevent GVHD, and preserve antitumor CTL.
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http://dx.doi.org/10.1126/scitranslmed.aai8269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6368389PMC
January 2017

Proteome-wide Profiling of Clinical PARP Inhibitors Reveals Compound-Specific Secondary Targets.

Cell Chem Biol 2016 Dec 17;23(12):1490-1503. Epub 2016 Nov 17.

Department of Drug Discovery, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA.

Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) are a promising class of targeted cancer drugs, but their individual target profiles beyond the PARP family, which could result in differential clinical use or toxicity, are unknown. Using an unbiased, mass spectrometry-based chemical proteomics approach, we generated a comparative proteome-wide target map of the four clinical PARPi, olaparib, veliparib, niraparib, and rucaparib. PARPi as a class displayed high target selectivity. However, in addition to the canonical targets PARP1, PARP2, and several of their binding partners, we also identified hexose-6-phosphate dehydrogenase (H6PD) and deoxycytidine kinase (DCK) as previously unrecognized targets of rucaparib and niraparib, respectively. Subsequent functional validation suggested that inhibition of DCK by niraparib could have detrimental effects when combined with nucleoside analog pro-drugs. H6PD silencing can cause apoptosis and further sensitize cells to PARPi, suggesting that H6PD may be, in addition to its established role in metabolic disorders, a new anticancer target.
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http://dx.doi.org/10.1016/j.chembiol.2016.10.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5182133PMC
December 2016

Inhibition of Shp2 suppresses mutant EGFR-induced lung tumors in transgenic mouse model of lung adenocarcinoma.

Oncotarget 2015 Mar;6(8):6191-202

Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA.

Epidermal growth factor receptor (EGFR) mutants drive lung tumorigenesis and are targeted for therapy. However, resistance to EGFR inhibitors has been observed, in which the mutant EGFR remains active. Thus, it is important to uncover mediators of EGFR mutant-driven lung tumors to develop new treatment strategies. The protein tyrosine phosphatase (PTP) Shp2 mediates EGF signaling. Nevertheless, it is unclear if Shp2 is activated by oncogenic EGFR mutants in lung carcinoma or if inhibiting the Shp2 PTP activity can suppress EGFR mutant-induced lung adenocarcinoma. Here, we generated transgenic mice containing a doxycycline (Dox)-inducible PTP-defective Shp2 mutant (tetO-Shp2CSDA). Using the rat Clara cell secretory protein (CCSP)-rtTA-directed transgene expression in the type II lung pneumocytes of transgenic mice, we found that the Gab1-Shp2 pathway was activated by EGFRL858R in the lungs of transgenic mice. Consistently, the Gab1-Shp2 pathway was activated in human lung adenocarcinoma cells containing mutant EGFR. Importantly, Shp2CSDA inhibited EGFRL858R-induced lung adenocarcinoma in transgenic animals. Analysis of lung tissues showed that Shp2CSDA suppressed Gab1 tyrosine phosphorylation and Gab1-Shp2 association, suggesting that Shp2 modulates a positive feedback loop to regulate its own activity. These results show that inhibition of the Shp2 PTP activity impairs mutant EGFR signaling and suppresses EGFRL858R-driven lung adenocarcinoma.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4467431PMC
http://dx.doi.org/10.18632/oncotarget.3356DOI Listing
March 2015

Development of novel ACK1/TNK2 inhibitors using a fragment-based approach.

J Med Chem 2015 Mar 17;58(6):2746-63. Epub 2015 Mar 17.

§Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33620, United States.

The tyrosine kinase ACK1, a critical signal transducer regulating survival of hormone-refractory cancers, is an important therapeutic target, for which there are no selective inhibitors in clinical trials to date. This work reports the discovery of novel and potent inhibitors for ACK1 tyrosine kinase (also known as TNK2) using an innovative fragment-based approach. Focused libraries were designed and synthesized by selecting fragments from reported ACK inhibitors to create hybrid structures in a mix and match process. The hybrid library was screened by enzyme-linked immunosorbent assay-based kinase inhibition and (33)P HotSpot assays. Systematic structure-activity relationship studies led to the identification of compound (R)-9b, which shows potent in vitro (IC50 = 56 nM, n = 3, (33)P HotSpot assay) and in vivo (IC50 < 2 μM, human cancer cell lines) ACK1 inhibition. Both (R)-9b and (S)-9b were stable in human plasma and displayed a long half-life (t(1/2) > 6 h).
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http://dx.doi.org/10.1021/jm501929nDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4605435PMC
March 2015

CD4+ T cell STAT3 phosphorylation precedes acute GVHD, and subsequent Th17 tissue invasion correlates with GVHD severity and therapeutic response.

J Leukoc Biol 2015 Apr 6;97(4):807-19. Epub 2015 Feb 6.

Departments of *Blood and Marrow Transplantation, Immunology, Hematopathology and Laboratory Medicine, Drug Discovery, and Biostatistics, Analytic Microscopy Core, H. Lee Moffitt Cancer Center, Tampa, Florida, USA.

Th17 cells contribute to severe GVHD in murine bone marrow transplantation. Targeted deletion of the RORγt transcription factor or blockade of the JAK2-STAT3 axis suppresses IL-17 production and alloreactivity by Th17 cells. Here, we show that pSTAT3 Y705 is increased significantly in CD4(+) T cells among human recipients of allogeneic HCT before the onset of Grade II-IV acute GVHD. Examination of target-organ tissues at the time of GVHD diagnosis indicates that the amount of RORγt + Th17 cells is significantly higher in severe GVHD. Greater accumulation of tissue-resident Th17 cells also correlates with the use of MTX- compared with Rapa-based GVHD prophylaxis, as well as a poor therapeutic response to glucocorticoids. RORγt is optimally suppressed by concurrent neutralization of TORC1 with Rapa and inhibition of STAT3 activation with S3I-201, supporting that mTOR- and STAT3-dependent pathways converge upon RORγt gene expression. Rapa-resistant T cell proliferation can be totally inhibited by STAT3 blockade during initial allosensitization. We conclude that STAT3 signaling and resultant Th17 tissue accumulation are closely associated with acute GVHD onset, severity, and treatment outcome. Future studies are needed to validate the association of STAT3 activity in acute GVHD. Novel GVHD prevention strategies that incorporate dual STAT3 and mTOR inhibition merit investigation.
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http://dx.doi.org/10.1189/jlb.5A1114-532RRDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370048PMC
April 2015

ACK1 tyrosine kinase interacts with histone demethylase KDM3A to regulate the mammary tumor oncogene HOXA1.

J Biol Chem 2014 Oct 22;289(41):28179-91. Epub 2014 Aug 22.

From the Drug Discovery Department, Moffitt Cancer Center, and the Department of Oncologic Sciences, College of Medicine, University of South Florida, Tampa, Florida 33612

Hormone therapy with the selective estrogen-receptor modulator tamoxifen provides a temporary relief for patients with estrogen receptor α (ER)-positive breast cancers. However, a subset of patients exhibiting overexpression of the HER2 receptor tyrosine kinase displays intrinsic resistance to tamoxifen therapy. Therefore, elucidating the mechanisms promoting the estrogen (E2)-independent ER-regulated gene transcription in tamoxifen-resistant breast tumors is essential to identify new therapeutic avenues to overcome drug resistance and ameliorate poor prognosis. The non-receptor tyrosine kinase, ACK1 (also known as TNK2), has emerged as a major integrator of signaling from various receptor tyrosine kinases including HER2. We have uncovered that heregulin-mediated ACK1 activation promoted ER activity in the presence of tamoxifen, which was significantly down-regulated upon ACK1 knockdown or inhibition of ACK1 by small molecule inhibitors, AIM-100 or Dasatinib. We report that ACK1 phosphorylates the ER co-activator, KDM3A, a H3K9 demethylase, at an evolutionary conserved tyrosine 1114 site in a heregulin-dependent manner, even in the presence of tamoxifen. Consistent with this finding, ACK1 activation resulted in a significant decrease in the deposition of dimethyl H3K9 epigenetic marks. Conversely, inhibition of ACK1 by AIM-100 or Dasatinib restored dimethyl H3K9 methylation marks and caused transcriptional suppression of the ER-regulated gene HOXA1. Thus, by its ability to regulate the epigenetic activity of an ER co-activator KDM3A, ACK1 modulates HOXA1 expression in the absence of E2, conferring tamoxifen resistance. These data reveal a novel therapeutic option, suppression of ACK1 signaling by AIM-100 or Dasatinib, to mitigate HOXA1 up-regulation in breast cancer patients displaying tamoxifen resistance.
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http://dx.doi.org/10.1074/jbc.M114.584425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4192474PMC
October 2014

Dual Aurora A and JAK2 kinase blockade effectively suppresses malignant transformation.

Oncotarget 2014 May;5(10):2947-61

Drug Discovery Department, Chemical Biology and Molecular Medicine Program, Chemical Biology Core Moffitt Cancer Center and Research Institute.

Aurora A and JAK2 kinases are involved in cell division and tumor cell survival, respectively. Here we demonstrate that ectopic expression of Aurora A and JAK2 together is more effective than each alone at inducing non-transformed cells to grow in an anchorage-independent manner and to invade. Furthermore, siRNA silencing or pharmacological inhibition of Aurora A and JAK2 with Alisertib and Ruxolitinib, respectively, is more effective than blocking each kinase alone at suppressing anchorage-dependent and -independent growth and invasion as well as at inducing apoptosis. Importantly, we have developed dual Aurora and JAK inhibitors, AJI-214 and AJI-100, which potently inhibit Aurora A, Aurora B and JAK2 in vitro. In human cancer cells, these dual inhibitors block the auto-phosphorylation of Aurora A (Thr-288) and the phosphorylation of the Aurora B substrate histone H3 (Ser-10) and the JAK2 substrate STAT3 (Tyr-705). Furthermore, AJI-214 and AJI-100 inhibit anchorage dependent and independent cell growth and invasion and induce G2/M cell cycle accumulation and apoptosis. Finally, AJI-100 caused regression of human tumor xenografts in mice. Taken together, our genetic and pharmacological studies indicate that targeting Aurora A and JAK2 together is a more effective approach than each kinase alone at inhibiting malignant transformation and warrant further advanced pre clinical investigations of dual Aurora A/JAK2 inhibitors as potential anti tumor agents.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4102782PMC
http://dx.doi.org/10.18632/oncotarget.1615DOI Listing
May 2014

Discovery of PI-1840, a novel noncovalent and rapidly reversible proteasome inhibitor with anti-tumor activity.

J Biol Chem 2014 Apr 25;289(17):11906-11915. Epub 2014 Feb 25.

Drug Discovery Department, H. Lee Moffit Cancer Center and Research Institute, Tampa, Florida 33612; Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33620. Electronic address:

The proteasome inhibitor bortezomib is effective in hematologic malignancies such as multiple myeloma but has little activity against solid tumors, acts covalently, and is associated with undesired side effects. Therefore, noncovalent inhibitors that are less toxic and more effective against solid tumors are desirable. Structure activity relationship studies led to the discovery of PI-1840, a potent and selective inhibitor for chymotrypsin-like (CT-L) (IC50 value = 27 ± 0.14 nm) over trypsin-like and peptidylglutamyl peptide hydrolyzing (IC50 values >100 μm) activities of the proteasome. Furthermore, PI-1840 is over 100-fold more selective for the constitutive proteasome over the immunoproteasome. Mass spectrometry and dialysis studies demonstrate that PI-1840 is a noncovalent and rapidly reversible CT-L inhibitor. In intact cancer cells, PI-1840 inhibits CT-L activity, induces the accumulation of proteasome substrates p27, Bax, and IκB-α, inhibits survival pathways and viability, and induces apoptosis. Furthermore, PI-1840 sensitizes human cancer cells to the mdm2/p53 disruptor, nutlin, and to the pan-Bcl-2 antagonist BH3-M6. Finally, in vivo, PI-1840 but not bortezomib suppresses the growth in nude mice of human breast tumor xenografts. These results warrant further evaluation of a noncovalent and rapidly reversible proteasome inhibitor as potential anticancer agents against solid tumors.
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http://dx.doi.org/10.1074/jbc.M113.533950DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4002098PMC
April 2014

GSK3 alpha and beta are new functionally relevant targets of tivantinib in lung cancer cells.

ACS Chem Biol 2014 Feb 20;9(2):353-8. Epub 2013 Nov 20.

Department of Drug Discovery, ‡Department of Thoracic Oncology, and §Molecular Oncology and Proteomics, H. Lee Moffitt Cancer Center & Research Institute , Tampa, Florida 33612-9497, United States.

Tivantinib has been described as a potent and highly selective inhibitor of the receptor tyrosine kinase c-MET and is currently in advanced clinical development for several cancers including non-small cell lung cancer (NSCLC). However, recent studies suggest that tivantinib's anticancer properties are unrelated to c-MET inhibition. Consistently, in determining tivantinib's activity profile in a broad panel of NSCLC cell lines, we found that, in contrast to several more potent c-MET inhibitors, tivantinib reduces cell viability across most of these cell lines. Applying an unbiased, mass-spectrometry-based, chemical proteomics approach, we identified glycogen synthase kinase 3 (GSK3) alpha and beta as novel tivantinib targets. Subsequent validation showed that tivantinib displayed higher potency for GSK3α than for GSK3β and that pharmacological inhibition or simultaneous siRNA-mediated loss of GSK3α and GSK3β caused apoptosis. In summary, GSK3α and GSK3β are new kinase targets of tivantinib that play an important role in its cellular mechanism-of-action in NSCLC.
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http://dx.doi.org/10.1021/cb400660aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3944088PMC
February 2014

Lysophosphatidic acid acyltransferase beta regulates mTOR signaling.

PLoS One 2013 31;8(10):e78632. Epub 2013 Oct 31.

Department of Experimental Therapeutics, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America.

Lysophosphatidic acid acyltransferase (LPAAT-β) is a phosphatidic acid (PA) generating enzyme that plays an essential role in triglyceride synthesis. However, LPAAT-β is now being studied as an important regulator of cell growth and differentiation and as a potential therapeutic target in cancer since PA is necessary for the activity of key proteins such as Raf, PKC-ζ and mTOR. In this report we determine the effect of LPAAT-β silencing with siRNA in pancreatic adenocarcinoma cell lines. We show for the first time that LPAAT-β knockdown inhibits proliferation and anchorage-independent growth of pancreatic cancer cells. This is associated with inhibition of signaling by mTOR as determined by levels of mTORC1- and mTORC2-specific phosphorylation sites on 4E-BP1, S6K and Akt. Since PA regulates the activity of mTOR by modulating its binding to FKBP38, we explored the possibility that LPAAT-β might regulate mTOR by affecting its association with FKBP38. Coimmunoprecipitation studies of FKBP38 with mTOR show increased levels of FKBP38 associated with mTOR when LPAAT-β protein levels are knocked down. Furthermore, depletion of LPAAT-β results in increased Lipin 1 nuclear localization which is associated with increased nuclear eccentricity, a nuclear shape change that is dependent on mTOR, further confirming the ability of LPAAT-β to regulate mTOR function. Our results provide support for the hypothesis that PA generated by LPAAT-β regulates mTOR signaling. We discuss the implications of these findings for using LPAAT-β as a therapeutic target.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0078632PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3814986PMC
August 2014

Development of new -Arylbenzamides as STAT3 Dimerization Inhibitors.

Medchemcomm 2013 Jun;4(6):932-941

Departments of Drug Discovery, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, USA.

The -tosylsalicylamide () was used as a starting point for design and synthesis of novel STAT-3 dimerization inhibitors with improved drug-like qualities. The phosphonic acid and salicylic acids , with a shorter amide linker lacking the -tosyl group had improved STAT-3 inhibitory activity. The equivalent potencies observed by the replacement of phosphonic acid moiety of with 5-amino-2-hydroxybenzoic acid group as in further validates 5-amino-2-hydroxybenzoic acid as a phosphotyrosine mimic. The salicylic acid displayed improved whole cell activity. The focused library of salicylic acids with benzamide linker indicated that hydrophobic heptyl and cyclohexyl are the best tolerated R groups and a biphenyl ether (as the Ar group) significantly contributes to STAT3 inhibitory activity. Our docking studies indicated that the acidic groups of , and interact in the p-Tyr-705 binding site in a broadly similar manner, while the phenoxybenzoyl group and the cyclohexylbenzyl group occupying pY+1 and pY-X hydrophobic pockets respectively. The and cell based potency of warrants further development of this scaffold as STAT3 inhibitors.
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http://dx.doi.org/10.1039/C3MD20323ADOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3780559PMC
June 2013

Oxadiazole-isopropylamides as potent and noncovalent proteasome inhibitors.

J Med Chem 2013 May 13;56(10):3783-805. Epub 2013 May 13.

Drug Discovery Department, Moffitt Cancer Center , 12902 Magnolia Drive, Tampa, Florida 33612, USA.

Screening of the 50000 ChemBridge compound library led to the identification of the oxadiazole-isopropylamide 1 (PI-1833) which inhibited chymotrypsin-like (CT-L) activity (IC50 = 0.60 μM) with little effects on the other two major proteasome proteolytic activities, trypsin-like (T-L) and postglutamyl-peptide-hydrolysis-like (PGPH-L). LC-MS/MS and dialysis show that 1 is a noncovalent and rapidly reversible CT-L inhibitor. Focused library synthesis provided 11ad (PI-1840) with CT-L activity (IC50 = 27 nM). Detailed SAR studies indicate that the amide moiety and the two phenyl rings are sensitive toward modifications. Hydrophobic residues, such as propyl or butyl in the para position (not ortho or meta) of the A-ring and a m-pyridyl group as B-ring, significantly improve activity. Compound 11ad (IC50 = 0.37 μM) is more potent than 1 (IC50 = 3.5 μM) at inhibiting CT-L activity in intact MDA-MB-468 human breast cancer cells and inhibiting their survival. The activity of 11ad warrants further preclinical investigation of this class as noncovalent proteasome inhibitors.
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http://dx.doi.org/10.1021/jm400221dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3774303PMC
May 2013

A novel inhibitor of STAT3 homodimerization selectively suppresses STAT3 activity and malignant transformation.

Cancer Res 2013 Mar 15;73(6):1922-33. Epub 2013 Jan 15.

Department of Drug Discovery, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA.

STAT3-STAT3 dimerization, which involves reciprocal binding of the STAT3-SH2 domain to phosphorylated tyrosine-705 (Y-705), is required for STAT3 nuclear translocation, DNA binding, and transcriptional regulation of downstream target genes. Here, we describe a small molecule S3I-1757 capable of disrupting STAT3-STAT3 dimerization, activation, and malignant transforming activity. Fluorescence polarization assay and molecular modeling suggest that S3I-1757 interacts with the phospho-Y-705-binding site in the SH2 domain and displaces fluorescein-labeled GpYLPQTV phosphotyrosine peptide from binding to STAT3. We generated hemagglutinin (HA)-tagged STAT3 and FLAG-tagged STAT3 and showed using coimmunoprecipitation and colocalization studies that S3I-1757 inhibits STAT3 dimerization and STAT3-EGF receptor (EGFR) binding in intact cells. Treatment of human cancer cells with S3I-1757 (but not a closely related analog, S3I-1756, which does not inhibit STAT3 dimerization), inhibits selectively the phosphorylation of STAT3 over AKT1 and ERK1/2 (MAPK3/1), nuclear accumulation of P-Y705-STAT3, STAT3-DNA binding, and transcriptional activation and suppresses the expression levels of STAT3 target genes, such as Bcl-xL (BCL2L1), survivin (BIRC5), cyclin D1 (CCND1), and matrix metalloproteinase (MMP)-9. Furthermore, S3I-1757, but not S3I-1756, inhibits anchorage-dependent and -independent growth, migration, and invasion of human cancer cells, which depend on STAT3. Finally, STAT3-C, a genetically engineered mutant of STAT3 that forms a constitutively dimerized STAT3, rescues cells from the effects of S3I-1757 inhibition. Thus, we have developed S3I-1757 as a STAT3-STAT3 dimerization inhibitor capable of blocking hyperactivated STAT3 and suppressing malignant transformation in human cancer cells that depend on STAT3.
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http://dx.doi.org/10.1158/0008-5472.CAN-12-3175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030628PMC
March 2013