Project description:Dysregulated oncogenic serine/threonine kinases play a pathological role in diverse forms of malignancies, including multiple myeloma (MM), and thus represent potential therapeutic targets. Here, we evaluated the biological and functional role of p21-activated kinase 4 (PAK4), and its potential as a new target in MM for clinical applications. PAK4 promoted MM cell growth and survival via activation of MM survival signaling pathways, including the MEK-ERK pathway. Furthermore, treatment with orally bioavailable PAK4 allosteric modulator (KPT-9274) significantly impacted MM cell growth and survival in a large panel of MM cell lines and primary MM cells alone and in the presence of bone marrow microenvironment. Intriguingly, we have identified FGFR3 as a novel binding partner of PAK4 and observed significant activity of KPT-9274 against t(4;14)-positive MM cells. These data support PAK4 as an oncogene in myeloma, and provide the rationale for the clinical evaluation of PAK4 modulator in myeloma.
Project description:Using multi-omic analyses, we identified PAK4 (P21 (RAC1) Activated Kinase 4) amplification and overexpression of Kinase PAK4 in a subset of bladder cancers. We confirmed the role of PAK4 in bladder cancer cell proliferation and invasion by in vitro experiments. Furthermore, our studies showed that PAK4 inhibitor is effective in curtailing bladder cancer cell growth. In order to understand the effect of PAK4 inhibition and knockdown on bladder cancer transcriptome, we performed RNA-sequencing of PAK4 siRNA transfected and PAK4 inhibitor (PF-3758309) treated bladder cancer cells (VM-CUB1). Analyses led to identification of direct targets of PAK4 in bladder cancer and associated pathways.
Project description:p21-activated kinase 4 (PAK4) is a serine/threonine kinase critical during development and with a proposed role in cancer and related cellular processes, including cell proliferation, survival and migration. However, while a limited number of PAK4-interacting proteins have been identified, the PAK4 interactome has not been systematically characterized. Here, we employed iTRAQ-based quantitative mass spectrometry of PAK4-immunioprecipitations from three distinct isolated cellular fractions to comprehensively profile the PAK4 interactome in human. These data will provide a valuable resource for further investigations on the role of PAK4 in physiology and disease.
Project description:This study aimed to address the challenges in treating multiple myeloma (MM) and its advanced stage, relapsed and refractory multiple myeloma (RRMM), by identifying new therapeutic targets. Clinical data were collected from 132 MM patients. Through propensity score matching, bone marrow samples from 24 MM patients and 6 control individuals were selected for RNA sequencing analysis. Western blot validation was performed in cell lines to investigate the role of serine/threonine-protein kinase D2 (PRKD2) in MM and RRMM. Additionally, gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, immune infiltration analysis, and drug sensitivity screening were conducted. The study found PRKD2 to be significantly upregulated in MM and RRMM, suggesting its potential as a therapeutic target. Functional assays indicated that disrupting PRKD2 inhibited myeloma cell proliferation, and pathway analysis revealed immune-related pathway alterations associated with PRKD2 expression. Drug sensitivity analysis identified Axitinib as a potential therapeutic agent targeting PRKD2, highlighting its promise for MM treatment.
Project description:Human PAK4 is an ubiquitously expressed p21-activated kinase which acts downstream of Cdc42. Since PAK4 is demonstrably enriched in cell-cell junctions, we probed the local protein environment around the kinase with a view to understanding its location and substrates. In U2OS cells expressing PAK4-BirA-GFP the resultant SILAC proximity analyses revealed a subset of 28 proteins that are primarily cell-cell junction components. The protein with highest relative biotin labelling was Afadin/AF6, which associates with the nectin family of homophilic junctional proteins. Reciprocally >50% of the PAK4-proximal proteins were identified by Afadin BioID. Pull-down experiments failed to identify junctional proteins, emphasizing the advantage of the BioID method. Mechanistically PAK4 depended on Afadin for its junctional localization, which is similar to the situation in Drosophila. A highly ranked PAK4-proximal protein LZTS2 was immuno-localized with Afadin at cell-cell junctions. Though PAK4 and Cdc42 are junctional, BioID analysis did not yield conventional cadherins, indicating their spatial segregation. To identify cellular PAK4 substrates we then assessed changes in phospho-proteome after 12 min PF-3758309 treatment. Among the PAK4-proximal junctional proteins 17 PAK4 sites were identified. Thus we show PAK4 is selective for the mammalian Afadin/nectin sub-compartment, with a demonstrably distinct localization from tight and cadherin junctions.
Project description:Multiple myeloma is a plasma cell malignancy that is susceptible to drugs targeting protein homeostasis such as thalidomide analogues and proteasome inhibitors. Thalidomide analogues modulate the activity of DDB1/CUL4 E3-ligase complexes to perturb substrate recognition and proteasomal degradation thereof. We hypothesised that the cellular pool of DDB1/CUL4 associated factors (DCAFs) may mediate other essential plasma cell processes and offer new targets for therapeutic intervention. Unbiased genetic screening identified DCAF1 (also known as Vpr-binding protein; VPRBP) as essential for myeloma cell survival with a multidomain structure offering several distinct opportunities for drug development. Utilising B32B3, a previously disclosed DCAF1 kinase inhibitor as a template, we developed a series of analogues with enhanced anti-myeloma potency. As anti-myeloma activity did not associate with dephosphorylation of known DCAF1 kinase substrates, we correlated drug-induced cellular phenotypes with whole-genome CRISPR/Cas9 resistance screening to further define mechanistic activity. These studies identified B32B3 analogues as microtubular destabilising agents with potential DCAF1 kinase independent properties and in vivo efficacy in multiple myeloma and lymphoma.
Project description:Multiple myeloma is a plasma cell malignancy that is susceptible to drugs targeting protein homeostasis such as thalidomide analogues and proteasome inhibitors. Thalidomide analogues modulate the activity of DDB1/CUL4 E3-ligase complexes to perturb substrate recognition and proteasomal degradation thereof. We hypothesised that the cellular pool of DDB1/CUL4 associated factors (DCAFs) may mediate other essential plasma cell processes and offer new targets for therapeutic intervention. Unbiased genetic screening identified DCAF1 (also known as Vpr-binding protein; VPRBP) as essential for myeloma cell survival with a multidomain structure offering several distinct opportunities for drug development. Utilising B32B3, a previously disclosed DCAF1 kinase inhibitor as a template, we developed a series of analogues with enhanced anti-myeloma potency. As anti-myeloma activity did not associate with dephosphorylation of known DCAF1 kinase substrates, we correlated drug-induced cellular phenotypes with whole-genome CRISPR/Cas9 resistance screening to further define mechanistic activity. These studies identified B32B3 analogues as microtubular destabilising agents with potential DCAF1 kinase independent properties and in vivo efficacy in multiple myeloma and lymphoma.
Project description:Multiple myeloma is a plasma cell malignancy that is susceptible to drugs targeting protein homeostasis such as thalidomide analogues and proteasome inhibitors. Thalidomide analogues modulate the activity of DDB1/CUL4 E3-ligase complexes to perturb substrate recognition and proteasomal degradation thereof. We hypothesised that the cellular pool of DDB1/CUL4 associated factors (DCAFs) may mediate other essential plasma cell processes and offer new targets for therapeutic intervention. Utilising B32B3, a previously disclosed DCAF1 kinase inhibitor as a template, we developed a series of analogues with enhanced anti-myeloma potency.
Project description:Mechanisms of constitutive NF-kappaB signaling in multiple myeloma are unknown. An inhibitor of IkappaB kinase beta (IKKbeta), targeting the classical NF-kappaB pathway, was lethal to many myeloma cell lines. Several had elevated expression of NIK due to genomic alterations or enhanced protein stability while others had inactivating mutations or deletion of TRAF3. Both abnormalities triggered the classical and alternative NF-kappaB pathways. A majority of primary myeloma patient samples and cell lines had elevated NF-kappaB target gene expression, often associated with genetic and epigenetic alteration of NIK, TRAF3, CYLD, BIRC2/BIRC3, CD40, NFKB1, and NFKB2. These genetic and functional data demonstrate that addiction to the NF-kappaB pathway is a frequent feature of myeloma and suggest that IKKbeta inhibitors hold promise for the treatment of this disease. Keywords: time series design