A novel intronic circular RNA circFGFR1int2 up-regulates FGFR1 by recruiting transcriptional activators P65/FUS and suppressing miR-4687-5p to promote prostate cancer progression

Fibroblast growth factor receptor 1 (FGFR1) is a core component of the FGFs/FGFR pathway that activates multiple signalling pathways, including ERK1/2, PI3K/AKT, PLCγ, and NF-κB. Aberrant expression of FGFR1 due to gene amplification, chromosome rearrangement, point mutation, and epigenetic deregulations, have been reported in various cancers. FGFR1 overexpression has also been reported in prostate cancer (PCa), but the underlining mechanisms are not clear. Here we report a novel circular RNA, circFGFR1int2, derived from intron 2 of FGFR1 gene, which is overexpressed in PCa and associated with tumor progression. Importantly, we show that circFGFR1int2 facilitates FGFR1 transcription by recruiting transcription activators P65/FUS and by interacting with FGFR1 promoter. Moreover, we show that circFGFR1int2 suppresses post-transcriptional inhibitory effects of miR-4687-5p on FGFR1 mRNA. These mechanisms synergistically promote PCa cell growth, migration, and invasion. Overexpression of circFGFR1int2 is significantly correlated with higher tumor grade, Gleason score, and PSA level, and is a significant unfavorable prognosticator for CRPC-free survival (CFS) (RR = 3.277, 95% confidence interval: 1.192-9.009; P = 0.021). These findings unravelled novel mechanisms controlling FGFR1 gene expression by intronic circRNA and its potential clinicopathological utility as a diagnostic or therapeutic target.

Design, synthesis and evaluation of novel pyrimidinylaminothiophene derivatives as FGFR1 inhibitors against human glioblastoma multiforme

Vascular endothelial growth factor receptors (VEGFRs) have emerged as the most promising anti-angiogenic therapeutic targets for the treatment of recurrent glioblastomas (GBM). However, anti-VEGF treatments led to the high proportion of non-responder patients or non lasting clinical response and the tumor progression to the greater malignant stage. To overcome these problems, there is an utmost need to develop innovative anti-angiogenic therapies. In this study, we report the development of a series of new FGFR1 inhibitors. Among them, compound 4i was able to potently inhibit FGFR1 kinase activities both in vitro and in vivo. This compound displayed strong anti-angiogenic activity in HUVECs and anti-tumor growth and anti-invasion effects in U-87MG cell line. These results emphasize the importance of FGFR1-mediated signaling pathways in GBM and reveal that pharmacological inhibition of FGFR1 can enhance the anti-tumoral, anti-angiogenic and anti-metastatic efficiency against GBM. These data support targeting of FGFR1 as a novel anti-angiogenic strategy and highlight the potential of compound 4i as a promising anti-angiogenic and anti-metastatic candidate for GBM therapy.

FGFR1 gene fusions in a subset of pediatric mesenchymal tumors: Expanding the genetic spectrum of tumors sharing histologic overlap with infantile fibrosarcoma and "NTRK-rearranged" spindle cell neoplasms

As the classification of kinase-driven spindle cell tumors continues to evolve, we describe the first series of pediatric mesenchymal tumors harboring FGFR1 gene fusions that share histologic overlap with infantile fibrosarcoma and "NTRK-rearranged" spindle cell neoplasms. Herein, we present three cases of FGFR1-rearranged pediatric mesenchymal tumors, including one case with FGFR1::PARD6B gene fusion and two cases with FGFR1::EBF2 gene fusion. The tumors involved infants ranging from 3 to 9 months in age with a male-to-female ratio of 2:1. All tumors involved the deep soft tissue of the gluteal, pelvic, or perirectal region. Histologically, the tumors comprised a cellular spindle cell neoplasm with primitive stellate cells, focal myxoid stroma, focal epithelioid features, no necrosis, and occasional mitotic figures (2-6 per 10 high-power field). By immunohistochemistry, the neoplastic cells focally expressed CD34 but lacked expression of S100 protein, SMA, desmin, myogenin, MyoD1, pan-TRK, and ALK. These three cases, including a case with long-term clinical follow-up, demonstrate that FGFR1 fusions occur in a subset of newly described pediatric kinase-driven mesenchymal tumors with locally aggressive behavior. Importantly, knowledge of these genetic alterations in this spectrum of pediatric tumors is key for diagnostic and targeted therapeutic purposes.

Case Report: A novel FGFR1 fusion in acute B-lymphoblastic leukemia identified by RNA sequencing

8p11 myeloproliferative syndrome is a rare hematological malignancy with aggressive course caused by the various translocation of FGFR1. In this study, a novel FGFR1 fusion was identified by RNA sequencing in a 28-year-old male patient with acute B-lymphoblastic leukemia. The patient harbors an in-frame fusion between KIF5B exon 15 and FGFR1 exon 10. The FGFR1 fusion and its protein expression was validated by Sanger sequencing and Western blot. Meanwhile, cytogenetic analysis reported a normal karyotype and targeted DNA sequencing identified no driver mutations, respectively. Despite he achieved complete remission after induction regimen, a relapse occurred and he became refractory to chemotherapy, and salvage haploidentical hematopoietic stem cell transplantation failed to control the progressive disease. In conclusion, we present the first case of KIF5B-FGFR1 fusion in hematological malignancy. These findings extend the spectrum of translocation in 8p11 myeloproliferative syndrome, and demonstrate the great prospect of RNA sequencing in clinical practice again.

Clinical development and management of adverse events associated with FGFR inhibitors

Approved fibroblast growth factor receptor (FGFR) inhibitors include erdafitinib, pemigatinib, and futibatinib. We review the most common toxicities associated with FGFR inhibitors and provide practical advice regarding their management. Hyperphosphatemia can be managed with careful monitoring, dose reduction or interruption, a prophylactic low-phosphate diet, and phosphate-lowering therapy. Ocular adverse events (AEs) are managed by withholding or adjusting the dose of the FGFR inhibitor. Dermatologic AEs include alopecia, which can be managed with minoxidil, and dry skin, which can be treated with moisturizers. Hand-foot syndrome can be prevented by lifestyle changes and managed with moisturizing creams, urea, or salicylic acid. Among gastrointestinal AEs, diarrhea may be managed with loperamide; stomatitis can be managed with baking soda rinses, mucosa-coating agents, and topical anesthetics; and dry mouth may be alleviated with salivary stimulants. Most FGFR inhibitor-associated toxicities are manageable with prophylactic measures and treatments; proactive monitoring is key to ensuring optimal clinical benefits.

FGFR1 variants contributed to families with tooth agenesis

BACKGROUND

Tooth agenesis is a common dental anomaly that can substantially affect both the ability to chew and the esthetic appearance of patients. This study aims to identify possible genetic factors that underlie various forms of tooth agenesis and to investigate the possible molecular mechanisms through which human dental pulp stem cells may play a role in this condition.

RESULTS

Using whole-exome sequencing of a Han Chinese family with non-syndromic tooth agenesis, a rare mutation in FGFR1 (NM_001174063.2: c.103G > A, p.Gly35Arg) was identified as causative and confirmed by Sanger sequencing. Via GeneMatcher, another family with a known variant (NM_001174063.2: c.1859G > A, p.Arg620Gln) was identified and diagnosed with tooth agenesis and a rare genetic disorder with considerable intrafamilial variability. Fgfr1 is enriched in the ectoderm during early embryonic development of mice and showed sustained low expression during normal embryonic development of Xenopus laevis frogs. Functional studies of the highly conserved missense variant c.103G > A showed deleterious effects. FGFR1 (c.103G > A) was overexpressed compared to wildtype and promoted proliferation while inhibiting apoptosis in HEK293 and human dental pulp stem cells. Moreover, the c.103G > A variant was found to suppress the epithelial-mesenchymal transition. The variant could downregulate ID4 expression and deactivate the TGF-beta signaling pathway by promoting the expression of SMAD6 and SMAD7.

CONCLUSION

Our research broadens the mutation spectrum associated with tooth agenesis and enhances understanding of the underlying disease mechanisms of this condition.

Caudal Fgfr1 disruption produces localised spinal mis-patterning and a terminal myelocystocele-like phenotype in mice

Closed spinal dysraphisms are poorly understood malformations classified as neural tube (NT) defects. Several, including terminal myelocystocele, affect the distal spine. We have previously identified a NT closure-initiating point, Closure 5, in the distal spine of mice. Here, we document equivalent morphology of the caudal-most closing posterior neuropore (PNP) in mice and humans. Closure 5 forms in a region of active FGF signalling, and pharmacological FGF receptor blockade impairs its formation in cultured mouse embryos. Conditional genetic deletion of Fgfr1 in caudal embryonic tissues with Cdx2Cre diminishes neuroepithelial proliferation, impairs Closure 5 formation and delays PNP closure. After closure, the distal NT of Fgfr1-disrupted embryos dilates to form a fluid-filled sac overlying ventrally flattened spinal cord. This phenotype resembles terminal myelocystocele. Histological analysis reveals regional and progressive loss of SHH- and FOXA2-positive ventral NT domains, resulting in OLIG2 labelling of the ventral-most NT. The OLIG2 domain is also subsequently lost, eventually producing a NT that is entirely positive for the dorsal marker PAX3. Thus, a terminal myelocystocele-like phenotype can arise after completion of NT closure with localised spinal mis-patterning caused by disruption of FGFR1 signalling.

FGF21 prevents neuronal cell ferroptosis after spinal cord injury by activating the FGFR1/β-Klotho pathway

Spinal cord injury (SCI) is a kind of traumatic nervous system disease caused by neuronal death, causing symptoms like sensory, motor, and autonomic nerve dysfunction. The recovery of neurological function has always been a intractable problem that has greatly distressed individuals and society. Although the involvement of iron-dependent lipid peroxidation leading to nerve cell ferroptosis in SCI progression has been reported, the underlying mechanisms remain unaddressed. Thus, this study aimed to investigate the potential of recombinant human FGF21 (rhFGF21) in inhibiting ferroptosis of nerve cells and improving limb function after SCI, along with its underlying mechanisms. In vivo animal model showed that FGFR1, p-FGFR1, and β-Klotho protein gradually increased over time after injury, reaching a peak on the third day. Moreover, rhFGF21 treatment significantly reduced ACSL4, increased GPX4 expression, reduced iron deposition, and inhibited ferroptosis. Meanwhile, rhFGF21 decreased cell apoptosis following acute spinal cord damage. In contrast, FGFR1 inhibitor PD173074 partially reversed the rhFGF21-induced therapeutic effects. Overall, this work revealed that rhFGF21 activates the FGFR1/β-Klotho pathway to decrease ferroptosis of nerve cells, suggesting that FGF21 could be a new therapeutic target for SCI neurological rehabilitation.

[Effect of Juanbi Qianggu Formula on biological behaviors of fibroblast-like synoviocytes in rheumatoid arthritis by regulating FGFR1 signaling pathway based on network pharmacology and cell function experiments]

This study aimed to explore the molecular mechanism of Juanbi Qianggu Formula(JBQGF), an empirical formula formulated by the prestigious doctor in traditional Chinese medicine, in the treatment of rheumatoid arthritis based on network pharmacology and cell function experiments. The main active components and targets of JBQGF were obtained through Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP) and Encyclopedia of Traditional Chinese Medicine(ETCM), and the core targets underwent functional enrichment analysis and signaling pathway analysis. Cytoscape 3.6.0 was used to construct a visualized "active component-target-signaling pathway" network of JBQGF. After screening, nine potential pathways of JBQGF were obtained, mainly including G protein-coupled receptor signaling pathway and tyrosine kinase receptor signaling pathway. As previously indicated, the fibroblast growth factor receptor 1(FGFR1) signaling pathway was highly activated in active fibroblast-like synoviocytes(FLS) in rheumatoid arthritis, and cell and animal experiments demonstrated that inhibition of the FGFR1 signaling pathway could significantly reduce joint inflammation and joint destruction in collagen-induced arthritis(CIA) rats. In terms of the tyrosine kinase receptor signal transduction pathway, the analysis of its target genes revealed that FGFR1 might be a potential target of JBQGF for rheumatoid arthritis treatment. The biological effect of JBQGF by inhibiting FGFR1 phosphorylation was preliminarily verified by Western blot, Transwell invasion assay, and pannus erosion assay, thereby inhibiting matrix metalloproteinase 2(MMP2) and receptor activator of nuclear factor-κB ligand(RANKL) and suppressing the invasion of fibroblasts in rheumatoid arthritis and erosive effect of pannus bone. This study provides ideas for searching potential targets of rheumatoid arthritis treatment and TCM drugs through network pharmacology.

Characterization of the folding and binding properties of the PTB domain of FRS2 with phosphorylated and unphosphorylated ligands

PTB (PhosphoTyrosine Binding) domains are protein domains that exert their function by binding phosphotyrosine residues on other proteins. They are commonly found in a variety of signaling proteins and are important for mediating protein-protein interactions in numerous cellular processes. PTB domains can also exhibit binding to unphosphorylated ligands, suggesting that they have additional binding specificities beyond phosphotyrosine recognition. Structural studies have reported that the PTB domain from FRS2 possesses this peculiar feature, allowing it to interact with both phosphorylated and unphosphorylated ligands, such as TrkB and FGFR1, through different topologies and orientations. In an effort to elucidate the dynamic and functional properties of these protein-protein interactions, we provide a complete characterization of the folding mechanism of the PTB domain of FRS2 and the binding process to peptides mimicking specific regions of TrkB and FGFR1. By analyzing the equilibrium and kinetics of PTB folding, we propose a mechanism implying the presence of an intermediate along the folding pathway. Kinetic binding experiments performed at different ionic strengths highlighted the electrostatic nature of the interaction with both peptides. The specific role of single amino acids in early and late events of binding was pinpointed by site-directed mutagenesis. These results are discussed in light of previous experimental works on these protein systems.

A comprehensive genomic study of 390 H3F3A-mutant pediatric and adult diffuse high-grade gliomas, CNS WHO grade 4

Malignant brain tumors, known as H3K27-altered diffuse midline glioma (DMG) and H3G34-mutant diffuse hemispheric glioma (DHG), can affect individuals of all ages and are classified as CNS WHO grade 4. We comprehensively characterized 390 H3F3A-mutant diffuse gliomas (201 females, 189 males) arising in pediatric patients (under 20 years old) and adults (20 years and older) evaluated by the CGP program at Foundation Medicine between 2013 and 2020. We assessed information from pathology reports, histopathology review, and clinical data. The cohort included 304 H3K27M-mutant DMG (156 females, 148 males) and 86 H3G34-mutant DHG (45 females, 41 males). Median patient age was 20 years (1-74 years). The frequency of H3K27M-mutant DMG was similar in both pediatric and adult patients in our cohort-48.6% of the patients were over 20 years old, 31.5% over 30, and 18% over 40 at initial diagnosis. FGFR1 hotspot point mutations (N546K and K656E) were exclusively identified in H3K27M-mutant DMG tumors (64/304, 21%; p = 0.0001); these tend to occur in older patients (median age: 32.5 years) and mainly arose in the diencephalon. H3K27M-mutant DMG had higher rates of mutations in NF1 (31.0 vs 8.1%; p = 0.0001) and PIK3CA/PIK3R1 (27.9% vs 15.1%; p = 0.016) compared to H3G34-mutant DHG. However, H3G34-mutant DHG had higher rates of targetable alterations in cell-cycle pathway genes (CDK4 and CDK6 amplification; CDKN2A/B deletion) (27.0 vs 9.0%). Potentially targetable PDGFRA alterations were identified in ~ 20% of both H3G34-mutant DHG and H3K27M-mutant DMG. Overall, in the present study H3K27M-mutant DMG occurred at similar rates in both adult and patient patients. Through our analysis, we were able to identify molecular features characteristic of DMG and DHG. By identifying the recurrent co-mutations including actionable FGFR1 point mutations found in nearly one-third of H3K27M-mutant DMG in young adults, our findings can inform clinical translational studies, patient diagnosis, and clinical trial design.

N-glycosylation acts as a switch for FGFR1 trafficking between the plasma membrane and nuclear envelope

Fibroblast growth factor receptor 1 (FGFR1) is a heavily N-glycosylated cell surface receptor tyrosine kinase that transmits signals across the plasma membrane, in response to fibroblast growth factors (FGFs). Balanced FGF/FGFR1 signaling is crucial for the development and homeostasis of the human body, and aberrant FGFR1 is frequently observed in various cancers. In addition to its predominant localization to the plasma membrane, FGFR1 has also been detected inside cells, mainly in the nuclear lumen, where it modulates gene expression. However, the exact mechanism of FGFR1 nuclear transport is still unknown. In this study, we generated a glycosylation-free mutant of FGFR1, FGFR1.GF, and demonstrated that it is localized primarily to the nuclear envelope. We show that reintroducing N-glycans into the D3 domain cannot redirect FGFR1 to the plasma membrane or exclude the receptor from the nuclear envelope. Reestablishment of D2 domain N-glycans largely inhibits FGFR1 accumulation in the nuclear envelope, but the receptor continues to accumulate inside the cell, mainly in the ER. Only the simultaneous presence of N-glycans of the D2 and D3 domains of FGFR1 promotes efficient transport of FGFR1 to the plasma membrane. We demonstrate that while disturbed FGFR1 folding results in partial FGFR1 accumulation in the ER, impaired FGFR1 secretion drives FGFR1 trafficking to the nuclear envelope. Intracellular FGFR1.GF displays a high level of autoactivation, suggesting the presence of nuclear FGFR1 signaling, which is independent of FGF. Using mass spectrometry and proximity ligation assay, we identified novel binding partners of the nuclear envelope-localized FGFR1, providing insights into its cellular functions. Collectively, our data define N-glycosylation of FGFR1 as an important regulator of FGFR1 kinase activity and, most importantly, as a switchable signal for FGFR1 trafficking between the nuclear envelope and plasma membrane, which, due to spatial restrictions, shapes FGFR1 interactome and cellular function. Video Abstract.

FGF/FGFR1 system in paired breast tumor-adjacent and tumor tissues, associations with mammographic breast density and tumor characteristics

Introduction

Mammographic breast density (MBD) is an established breast cancer risk factor, yet the underlying molecular mechanisms remain to be deciphered. Fibroblast growth factor receptor 1 (FGFR1) amplification is associated with breast cancer development and aberrant FGF signaling found in the biological processes related to both high mammographic density and breast cancer microenvironment. The aim of this study was to investigate the FGF/FGFR1 expression in-between paired tumor-adjacent and tumor tissues from the same patient, and its associations with MBD and tumor characteristics.

Methods

FGFR1 expression in paired tissues from 426 breast cancer patients participating in the Karolinska Mammography Project for Risk Prediction of Breast Cancer (KARMA) cohort study was analyzed by immunohistochemistry. FGF ligand expression was obtained from RNA-sequencing data for 327 of the included patients.

Results

FGFR1 levels were differently expressed in tumor-adjacent and tumor tissues, with increased FGFR1 levels detected in 58% of the tumors. High FGFR1 expression in tumor tissues was associated with less favorable tumor characteristics; high histological grade (OR=1.86, 95% CI 1.00-3.44), high Ki67 proliferative index (OR=2.18, 95% CI 1.18-4.02) as well as tumors of Luminal B-like subtype (OR=2.56, 95%CI 1.29-5.06). While no clear association between FGFR1 expression and MBD was found, FGF ligand (FGF1, FGF11, FGF18) expression was positively correlated with MBD.

Discussion

Taken together, these findings support a role of the FGF/FGFR1 system in early breast cancer which warrants further investigation in the MBD-breast cancer context.

Fgfr1 deficiency in osteocytes leads to increased bone mass by enhancing Wnt/β-catenin signaling

Osteoporosis (OP) is the most common skeletal disease in middle-aged and elderly people. A comprehensive understanding of the pathogenesis of osteoporosis is important. Fibroblast growth factor receptor 1 (FGFR1) is an important molecule for skeletal development and bone remodeling. Osteocytes are the most numerous cells in bone and play critical roles in bone homeostasis, however the effect of FGFR1 on osteocytes is still unclear. To clarify the direct effects of FGFR1 on osteocytes, we conditionally deleted Fgfr1 in osteocytes with Dentin matrix protein 1 (Dmp1)-Cre. We found that mice lacking Fgfr1 in osteocytes (Fgfr1^f/f;Dmp-cre, MUT) showed increased trabecular bone mass at 2 and 6 months of age, which resulted from enhanced bone formation and decreased bone resorption. Furthermore, the cortical bone was thicker in WT mice than that in MUT mice at 2 and 6 months of age. Histological analysis showed that MUT mice had a decreased number of osteocytes but an increased number of osteocyte dendrites. We further found that mice lacking Fgfr1 in osteocytes showed enhanced activation of β-catenin signaling. The expression of sclerostin, an inhibitor of Wnt/β-catenin signaling, was obviously decreased in MUT mice. Furthermore, we found that FGFR1 can inhibit the expression of β-catenin and decrease the activity of β-catenin signaling. In brief, our study showed that FGFR1 in osteocytes can regulate bone mass by regulating Wnt/β-catenin signaling, providing genetic evidence that FGFR1 plays essential roles in osteocytes during bone remodeling and suggesting that FGFR1 is a potential therapeutic target for the prevention of bone loss.

Sustained remission of type 2 diabetes in rodents by centrally administered fibroblast growth factor 4

Type 2 diabetes (T2D) is a major health and economic burden worldwide. Despite the availability of multiple drugs for short-term management, sustained remission of T2D is currently not achievable pharmacologically. Intracerebroventricular administration of fibroblast growth factor 1 (icvFGF1) induces sustained remission in T2D rodents, propelling intense research efforts to understand its mechanism of action. Whether other FGFs possess similar therapeutic benefits is currently unknown. Here, we show that icvFGF4 also elicits a sustained antidiabetic effect in both male db/db mice and diet-induced obese mice by activating FGF receptor 1 (FGFR1) expressed in glucose-sensing neurons within the mediobasal hypothalamus. Specifically, FGF4 excites glucose-excited (GE) neurons while inhibiting glucose-inhibited (GI) neurons. Moreover, icvFGF4 restores the percentage of GI neurons in db/db mice. Importantly, intranasal delivery of FGF4 alleviates hyperglycemia in db/db mice, paving the way for non-invasive therapy. We conclude that icvFGF4 holds significant therapeutic potential for achieving sustained remission of T2D.

Pre-granulosa cell-derived FGF23 protects oocytes from premature apoptosis during primordial follicle formation by inhibiting p38 MAPK in mice

A large number of oocytes in the perinatal ovary in rodents get lost for unknown reasons. The granulosa cell-oocyte mutual communication is pivotal for directing formation of the primordial follicle, however little is known if paracrine factors participate in modulating programmed oocyte death perinatally. We report here that pre-granulosa cell-derived fibroblast growth factor 23 (FGF23) functioned in preventing oocyte apoptosis in the perinatal mouse ovary. Our results showed that FGF23 was exclusively expressed in pre-granulosa cells while fibroblast growth factor receptors (FGFRs) were specifically expressed in the oocytes in perinatal ovaries. FGFR1 was one of the representative receptors in mediating FGF23 signaling during the formation of the primordial follicle. In cultured ovaries, the number of alive oocytes declines significantly, accompanied by the activation of the p38 MAPK signaling pathway, under the condition of FGFR1 disruption by specific inhibitors of FGFR1 or silencing of Fgf23. As a result, oocyte apoptosis increased and eventually led to a decrease in the number of germ cells in perinatal ovaries following the treatments. In the perinatal mouse ovary, pre-granulosa cell-derived FGF23 binds to FGFR1 and activates at least, the p38 MAPK signaling pathway, thereby regulating the level of apoptosis during primordial follicle formation. This study re-emphasizes the importance of granulosa cell - oocyte mutual communication in modulating primordial follicle formation and supporting oocyte survival under physiological conditions.

Real-ambient particulate matter exposure-induced FGFR1 methylation contributes to cardiac dysfunction via lipid metabolism disruption

Particulate matter (PM)-induced cardiometabolic disorder contributes to the progression of cardiac diseases, but its epigenetic mechanisms are largely unknown. This study used bioinformatic analysis, in vivo and in vitro multiple models to investigate the role of PM-induced cardiac fibroblast growth factor 1 (FGFR1) methylation and its impact on cardiomyocyte lipid metabolic disruption. Bioinformatic analysis revealed that FGFR1 was associated with cardiac pathologies, mitochondrial function and metabolism, supporting the possibility that FGFR1 may play regulatory roles in PM-induced cardiac functional impairment and lipid metabolism disorders. Individually ventilated cage (IVC)-based real-ambient PM exposure system mouse models were used to expose C57/BL6 mice for six and fifteen weeks. The results showed that PM induced cardiac lipid metabolism disorder, DNA nucleotide methyltransferases (DNMTs) alterations and FGFR1 expression declines in mouse heart. Lipidomics analysis revealed that carnitines, phosphoglycerides and lysophosphoglycerides were most significantly affected by PM exposure. At the cellular level, AC16 cells treated with FGFR1 inhibitor (PD173074) led to impaired mitochondrial and metabolic functions in cardiomyocytes. Inhibition of DNA methylation in cells by 5-AZA partially restored the FGFR1 expression, ameliorated cardiomyocyte injury and mitochondrial functions. These changes involved alterations in AMP-activated protein kinase (AMPK)-peroxisome proliferator activated receptors gamma, coactivator 1 alpha (PGC1α) pathways. Bisulfite sequencing PCR (BSP) and DNA methylation specific PCR (MSP) confirmed that PM exposure induced FGFR1 gene promoter region methylation. These results suggested that, by inducing FGFR1 methylation, PM exposure would affect cardiac injury and deranged lipid metabolism. Overexpression of FGFR1 in mouse heart using adeno-associated virus 9 (AAV9) effectively alleviated PM-induced cardiac impairment and metabolic disorder. Our findings identified that FGFR1 methylation might be one of the potential indicators for PM-induced cardiac mitochondrial and metabolic dysfunction, providing novel insights into underlying PM-related cardiotoxic mechanisms.

Rhabdomyosarcoma With Epithelioid Features And NSD3::FOXO1 Fusion: Evidence For Reconsideration Of Previously Reported FOXO1::FGFR1 Fusion

Epithelioid rhabdomyosarcoma is a rare rhabdomyosarcoma variant for which no diagnostic recurrent driver genetic events have been identified. Here we report a rapidly progressive and widely metastatic rhabdomyosarcoma with epithelioid features that arose in the thigh of a male infant. Conventional cytogenetics revealed a t(8;13)(p11.2;q14) translocation. Fluorescence in situ hybridization studies showed rearrangement of FOXO1 and amplification of its 3" end, and rearrangement of NSD3 and amplification of its 5` end. Next generation sequencing identified a NSD3::FOXO1 fusion, which is a previously unreported gene fusion. We also review the historic report of a FOXO1::FGFR1 fusion in a solid variant of alveolar rhabdomyosarcoma and propose that NSD3::FOXO1 fusion may have been the more appropriate interpretation of the data presented in that report.

Progression-associated molecular changes in basal/squamous and sarcomatoid bladder carcinogenesis

The aggressive basal/squamous (Ba/Sq) bladder cancer (BLCA) subtype is often diagnosed at the muscle-invasive stage and can progress to the sarcomatoid variant. Identification of molecular changes occurring during progression from non-muscle-invasive BLCA (NMIBC) to Ba/Sq muscle-invasive BLCA (MIBC) is thus challenging in human disease. We used the N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) mouse model of Ba/Sq MIBC to study longitudinally the molecular changes leading to the Ba/Sq phenotype and to the sarcomatoid variant using IHC and microdissection followed by RNA-seq at all stages of progression. A shift to the Ba/Sq phenotype started in early progression stages. Pathway analysis of gene clusters with coordinated expression changes revealed Shh signaling loss and a shift from fatty acid metabolism to glycolysis. An upregulated cluster, appearing early in carcinogenesis, showed relevance to human disease, identifying NMIBC patients at risk of progression. Similar to the human counterpart, sarcomatoid BBN tumors displayed a Ba/Sq phenotype and epithelial-mesenchymal transition (EMT) features. An EGFR/FGFR1 signaling switch occurred with sarcomatoid dedifferentiation and correlated with EMT. BLCA cell lines with high EMT were the most sensitive to FGFR1 knockout and resistant to EGFR knockout. Taken together, these findings provide insights into the underlying biology of Ba/Sq BLCA progression and sarcomatoid dedifferentiation with potential clinical implications. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Significant association between FGFR1 mutation frequency and age in central giant cell granuloma

Central giant cell granulomas (CGCG) are rare intraosseous osteolytic lesions of uncertain aetiology. Despite the benign nature of this neoplasia, the lesions can rapidly grow and become large, painful, invasive, and destructive. The identification of molecular drivers could help in the selection of targeted therapies for specific cases. TRPV4, KRAS and FGFR1 mutations have been associated with these lesions but no correlation between the mutations and patient features was observed so far. In this study, we analysed 17 CGCG cases of an Italian cohort and identified an interesting and significant (p=0.0021) correlation between FGFR1 mutations and age. In detail, FGFR1 mutations were observed frequently and exclusively in CGCG from young (<18 years old) patients (4/5 lesions, 80%). Furthermore, the combination between ours and previously published data confirmed a significant difference in the frequency of FGFR1 mutations in CGCG from patients younger than 18 years at the time of diagnosis (9/23 lesions, 39%) when compared to older patients (1/31 lesions, 0.03%; p=0.0011), thus corroborating our observation in a cohort of 54 patients. FGFR1 variants in young CGCG patients could favour fast lesion growth, implying that they seek medical attention earlier. Our observation might help prioritise candidates for FGFR1 testing, thus opening treatment options with FGFR inhibitors.

Identification and Characterization of Peptides from Bovine Collagen Hydrolysates that Promote Myogenic Cell Proliferation

In this study, bovine collagen hydrolysate was purified via a series of chromatograms, and the peptides with the highest activity for promoting myoblast proliferation were identified by LC-MS-MS. It was demonstrated that the peptide GDAGPPGPAGPAGPPGPIG (hydroxylation) could promote C2C12 proliferation (+18.5% ± 0.04, P < 0.05). The certain peptide was capable of regulating the myogenic cell cycle and inhibiting myogenic cell apoptosis. By combining molecular docking, quantitative real-time PCR, and metabonomics, we suggested that the peptide GDAGPPGPAGPAGPPGPIG (hydroxylation) might bind to FGFR1 and affect the expression of genes downstream of FGFR1 and influence protein synthesis to promote myoblast proliferation. The above results showed that the peptides isolated in this study have the potential to alleviate sarcopenia in the elderly.

Fibroblast growth factor 5 (FGF5) and its missense mutant FGF5-H174 underlying trichomegaly: a molecular dynamics simulation investigation

The missense mutation Y174H of FGF5 (FGF5-H174) had been associated with trichomegaly, characterized by abnormally long and pigmented eyelashes. The amino acid tyrosine (Tyr/Y) at position 174 is conserved across many species, proposedly holding important characteristics for the functions of FGF5. Microsecond molecular dynamics simulations along with protein-protein docking and residue interacting network analysis were employed to investigate the structural dynamics and binding mode of both wild-type (FGF5-WT) and its mutated counterpart (FGF5-H174). It was found that the mutation decreased number of hydrogen bonds within the protein, sheet secondary structure, interaction of residue 174 with other residues, and number of salt-bridges. On the other hand, the mutation increased solvent accessible surface area, number of hydrogen bonds between the protein and solvent, coil secondary structure, protein C-alpha backbone root mean square deviation, protein residue root mean square fluctuations, as well as occupied conformational space. In addition, protein-protein docking integrated with molecular dynamics simulations and molecular mechanics - Poisson-Boltzmann surface area (MM/PBSA) binding energy calculation demonstrated that the mutated variant possessed stronger binding affinity towards fibroblast growth factor receptor 1 (FGFR1). However, residue interaction network analysis demonstrated that the binding mode of the FGFR1-FGF5-H174 complex was drastically different from that of the FGFR1-FGF5-WT complex. In conclusion, the missense mutation conferred more instability within itself and stronger binding affinity towards FGFR1 with distinctively altered binding mode or residue connectivity. These findings might help explain the decreased pharmacological activity of FGF5-H174 towards FGFR1, underlying trichomegaly.Communicated by Ramaswamy H. Sarma.

Mutation spectrum of Kallmann syndrome: identification of five novel mutations across ANOS1 and FGFR1

BACKGROUND

Kallmann syndrome (KS) is a common type of idiopathic hypogonadotropic hypogonadism. To date, more than 30 genes including ANOS1 and FGFR1 have been identified in different genetic models of KS without affirmatory genotype-phenotype correlation, and novel mutations have been found.

METHODS

A total of 35 unrelated patients with clinical features of disorder of sex development were recruited. Custom-panel sequencing or whole-exome sequencing was performed to detect the pathogenic mutations. Sanger sequencing was performed to verify single-nucleotide variants. Copy number variation-sequencing (CNV-seq) was performed to determine CNVs. The pathogenicity of the identified variant was predicted in silico. mRNA transcript analysis and minigene reporter assay were performed to test the effect of the mutation on splicing.

RESULTS

ANOS1 gene c.709 T > A and c.711 G > T were evaluated as pathogenic by several commonly used software, and c.1063-2 A > T was verified by transcriptional splicing assay. The c.1063-2 A > T mutation activated a cryptic splice acceptor site downstream of the original splice acceptor site and resulted in an aberrant splicing of the 24-basepair at the 5' end of exon 8, yielding a new transcript with c.1063-1086 deletion. FRFR1 gene c.1835delA was assessed as pathogenic according to the ACMG guideline. The CNV of del(8)(p12p11.22)chr8:g.36140000_38460000del was judged as pathogenic according to the ACMG & ClinGen technical standards.

CONCLUSIONS

Herein, we identified three novel ANOS1 mutations and two novel FGFR1 variations in Chinese KS families. In silico prediction and functional experiment evaluated the pathogenesis of ANOS1 mutations. FRFR1 c.1835delA mutation and del(8)(p12p11.22)chr8:g.36140000_38460000del were assessed as pathogenic variations. Therefore, our study expands the spectrum of mutations associated with KS and provides diagnostic evidence for patients who carry the same mutation in the future.

Short-term semaglutide treatment improves FGF21 responsiveness in primary hepatocytes isolated from high fat diet challenged mice

Metabolic functions of GLP-1 and its analogues have been extensively investigated. In addition to acting as an incretin and reducing body weight, we and others have suggested the existence of GLP-1/fibroblast growth factor 21 (FGF21) axis in which liver mediates certain functions of GLP-1 receptor agonists. In a more recent study, we found with surprise that four-week treatment with liraglutide but not semaglutide stimulated hepatic FGF21 expression in HFD-challenged mice. We wondered whether semaglutide can also improve FGF21 sensitivity or responsiveness and hence triggers the feedback loop in attenuating its stimulation on hepatic FGF21 expression after a long-term treatment. Here, we assessed effect of daily semaglutide treatment in HFD-fed mice for 7 days. HFD challenge attenuated effect of FGF21 treatment on its downstream events in mouse primary hepatocytes, which can be restored by 7-day semaglutide treatment. In mouse liver, 7-day semaglutide treatment stimulated FGF21 as well as genes that encode its receptor (FGFR1) and the obligatory co-receptor (KLB), and a battery of genes that are involved in lipid homeostasis. In epididymal fat tissue, expressions of a battery genes including Klb affected by HFD challenge were reversed by 7-day semaglutide treatment. We suggest that semaglutide treatment improves FGF21 sensitivity which is attenuated by HFD challenge.

Descriptor-free QSAR: effectiveness in screening for putative inhibitors of FGFR1

The long short-term memory (LSTM) algorithm has provided solutions to the limitations of the descriptors-utilizing QSAR models in drug design. However, the direct application of LSTM remains scarce. The effectiveness of a descriptor-free QSAR (LSTM-SM) in modeling the FGFR1 inhibitors dataset while comparing with two conventional QSAR using descriptors (126 bits Morgan fingerprint and 2 D descriptors respectively) as a baseline model was investigated in this study. The validated descriptor-free QSAR model was thereafter used to screen for active FGFR1 inhibitors in the ChemDiv database and subjected to molecular docking, induced-fit docking, QM-MM optimization, and molecular dynamics simulations to filter for compounds with high binding affinity and suggest the putative mechanism of inhibition and specificity. The LSTM-SM model performed better than conventional QSAR; having accuracy, specificity, and sensitivity of 0.92, model loss of 0.025, and AUC of 0.95. Fifteen thousand compounds were predicted as actives from the ChemDiv database and four compounds were finally selected. Of the four, two showed putatively effective binding interactions with key active site residues. Molecular dynamics simulations on these compounds in complex with the receptor further give insight into the conformational dynamics of each compound bounded to the receptor. The complexes formed are stable and exhibit a similar degree of compactness. Our findings predicted the advent of self-feature extracting machine learning algorithms of compounds, and have provided the possibility of better predictive model quality that is not necessarily limited by compound descriptors. The putative FGFR1 inhibitors, with their mechanism of inhibition and specificity, were elucidated using this approachCommunicated by Ramaswamy H. Sarma.