👤 Kuniyuki Kano

Futibatinib is the only covalent inhibitor of FGFR1-4 to gain regulatory approval in oncology. In this article, we present genomic analyses of tissue biopsies and circulating tumor DNA (ctDNA) from patients with 1 of nearly 20 tumor types treated with futibatinib in the phase I/II FOENIX study. Eligible patients included those with ctDNA samples collected per protocol at baseline and/or progression on futibatinib in the phase Ib portion of the study for FGF/FGFR-altered advanced solid tumors or the phase II portion of the study for FGFR2 fusion/rearrangement-positive cholangiocarcinoma. Assessments included analytical concordance between tumor and ctDNA analyses for detection of FGFR alterations, association of ctDNA-detected co-occurring genomic alterations with response to futibatinib, and determination of patterns of acquired resistance following progression on futibatinib. Among 300 patients treated with futibatinib, 226 were eligible for this analysis, including 139 (62%) with cholangiocarcinoma. Among patients with known FGFR2 fusions/rearrangements, FGFR1 fusions, FGFR3 fusions, or FGFR2 amplifications per tissue analysis, detection rates in ctDNA for these aberrations were 84%, 0%, 11%, and 59%, respectively. Objective response rates on futibatinib were not significantly different between patients with TP53-altered versus -unaltered solid tumors; progression-free survival was reduced in patients with CDKN2B-altered versus -unaltered cholangiocarcinoma (median 4.8 versus 11.0 months; P = 0.03). Acquired resistance to futibatinib was frequently polyclonal and driven by an array of mutations within the relevant FGFR kinase domain, predominantly V565L, V565F, and N550K variants. In this largest and most systematic analysis of acquired resistance to an FGFR inhibitor from prospective clinical trials, emergence of secondary FGFR2 kinase domain mutations was observed in most patients receiving clinical benefit to futibatinib. ctDNA analysis shows clinically relevant potential as a noninvasive method for assessing genomic profiles, identifying patients who may benefit from FGFR inhibitor treatment, and exploring acquired resistance mechanisms. Show less

Brown adipose tissue (BAT), a thermogenic tissue that plays an important role in systemic energy expenditure, has histological and functional sex differences. BAT thermogenic activity is higher in female mice than in male mice. However, the molecular mechanism underlying this functional sex difference has not been fully elucidated. Herein, we demonstrate the role and mechanism of PGC-1α in this sex difference. Inducible adipocyte-specific PGC-1α knockout (KO) mice display mitochondrial morphological defects and decreased BAT thermogenesis only in females. Expression of carbohydrate response-element binding protein beta (Chrebpβ) and its downstream de novo lipogenesis (DNL)-related genes are both reduced only in female KO mice. BAT-specific knockdown of ChREBPβ displays decreased DNL-related gene expression and mitochondrial morphological defects followed by reduced BAT thermogenesis in female wild-type mice. Lipidomics reveals that, PGC-1α increases ether-linked phosphatidylethanolamine (PE) and cardiolipin(18:2) Show less

Brahma-related gene 1 (BRG1), an ATPase subunit of the SWItch/sucrose non-fermentable (SWI/SNF) chromatin remodeling complex controls multipotent neural crest formation by regulating epithelial-mesenchymal transition (EMT)-related genes with adenosine triphosphate-dependent chromodomain-helicase DNA-binding protein 7 (CHD7). The expression of BRG1 engages in pre-mRNA splicing through interacting RNPs in cancers; however, the detailed molecular pathology of how BRG1and CHD7 relate to cancer development remains largely unveiled. This study demonstrated novel post-transcriptional regulation of BRG1 in EMT and relationship with FIRΔexon2, which is a splicing variant of the far-upstream element-binding protein (FUBP) 1-interacting repressor (FIR) lacking exon 2, which fails to repress c-myc transcription in cancers. Previously, we have reported that FIR complete knockout mice (FIR Show less

Glycero-lysophospholipids, such as lysophosphatidic acids and lysophosphatidylserine, are gathering attention, since specific receptors have been identified. Most of these compounds have been proposed to be bound to albumin, while their associations with lipoproteins have not been fully elucidated. Therefore, in this study, we aimed to investigate the contents of glycero-lysophospholipids (lysophosphatidic acids, lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylglycerol, lysophosphatidylinositol, and lysophosphatidylserine) on lipoproteins and the modulation of their metabolism by lipoprotein metabolism. We observed that moderate amounts of glycero-lysophospholipids, with the exception of lysophosphatidylserine, were distributed on the LDL and HDL fractions, and glycero-lysophospholipids that had bound to albumin were observed in lipoprotein fractions when they were co-incubated. The overexpression of cholesteryl ester transfer protein decreased the plasma levels of lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylglycerol, and lysophosphatidylinositol and it increased their contents in apoB-containing lipoproteins, while it decreased their contents in HDL and lipoprotein-depleted fractions in mice. The overexpression of the LDL receptor (LDLr) decreased the plasma levels of lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylglycerol, and lysophosphatidylinositol and decreased the contents of these compounds in the LDL, HDL, and lipoprotein-depleted fractions, while the knockdown of the LDLr increased them. These results suggest the potential importance of glycero-lysophospholipids in the pleiotropic effects of lipoproteins as well as the importance of lipoprotein metabolism in the regulation of glycero-lysophospholipids. Show less

Homeodomain-interacting protein kinase 2 (HIPK2) is a potential tumor suppressor that has a crucial role in the DNA damage response (DDR) by regulating cell-cycle checkpoint activation and apoptosis. However, it is unclear whether HIPK2 exerts distinct roles in DNA damage repair. The aim of this study was to identify novel target molecule(s) of HIPK2, which mediates HIPK2-dependent DNA damage repair. HIPK2-knockdown human colon cancer cells (HCT116) or hipk1/hipk2 double-deficient mouse embryonic fibroblasts could not remove histone H2A.X phosphorylated at Ser139 (γH2A.X) after irradiation with a sublethal dose (10 J/m(2)) of ultraviolet (UV)-C, resulting in apoptosis. Knockdown of HIPK2 in p53-null HCT116 cells similarly promoted the UV-C-induced γH2A.X accumulation and apoptosis. Proteomic analysis of HIPK2-associated proteins using liquid chromatography-tandem mass spectrometry identified heterochromatin protein 1γ (HP1γ) as a novel target for HIPK2. Immunoprecipitation experiments with HCT116 cells expressing FLAG-tagged HIPK2 and one of the HA-tagged HP1 family members demonstrated that HIPK2 specifically associated with HP1γ, but not with HP1α or HP1β, through its chromo-shadow domain. Mutation of the HP1box motif (883-PTVSV-887) within HIPK2 abolished the association. HP1γ knockdown also enhanced accumulation of γH2A.X and apoptosis after sublethal UV-C irradiation. In vitro kinase assay demonstrated an HP1γ-phosphorylating activity of HIPK2. Sublethal UV-C irradiation phosphorylated HP1γ. This phosphorylation was absent in endogenous HIPK2-silenced cells with HIPK2 3'UTR siRNA. Overexpression of FLAG-HIPK2, but not the HP1box-mutated or kinase-dead HIPK2 mutant, in the HIPK2-silenced cells increased HP1γ binding to trimethylated (Lys9) histone H3 (H3K9me3), rescued the UV-C-induced phosphorylation of HP1γ, triggered release of HP1γ from histone H3K9me3 and suppressed γH2A.X accumulation. Our results suggest that HIPK2-dependent phosphorylation of HP1γ may participate in the regulation of dynamic interaction between HP1γ and histone H3K9me3 to promote DNA damage repair. This HIPK2/HP1γ pathway may uncover a new functional aspect of HIPK2 as a tumor suppressor. Show less

Membrane-associated guanylate kinases (MAGUKs) are abundant postsynaptic density (PSD)-95/discs large/zona occludens-1 (PDZ)-containing proteins that can assemble receptors and associated signaling enzymes at sites of cell-cell contact, including synapses. PSD-93, a postsynaptic neuronal MAGUK, has three PDZ domains that can bind to specific ion channels, including NMDA delta2 type glutamate receptors, as well as Shaker and inward rectifier type K(+) channels, and can mediate clustering of these channels in heterologous cells. Genetic analyses of Drosophila show that MAGUKs play critical roles in synaptic development because mutations of discs large disrupt the subsynaptic reticulum and block postsynaptic clustering of Shaker K(+) channels. It is uncertain whether MAGUKs play an essential role in the development of central synapses. There are four neuronal MAGUKs with overlapping expression patterns in the mammalian brain; however, we find PSD-93 is the only MAGUK expressed in cerebellar Purkinje neurons. Therefore, we targeted disruption of PSD-93 in mouse. Despite the absence of MAGUK immunoreactivity in Purkinje neurons from the knock-outs, these mice have no structural or functional abnormality in cerebellum. Both the dendritic architecture and the postsynaptic localization of PSD-93 interacting proteins remain intact at light and electron microscopic levels in the knock-outs. Postsynaptic Purkinje cell responses, monosynaptic climbing fiber innervation, and cerebellar-dependent behaviors are also normal. Our data demonstrate that MAGUK proteins of the PSD-93/95 family are not essential for development of certain central synapses but may instead participate in specialized aspects of synaptic signaling and plasticity. Show less