👤 L S Mertens

FGFR inhibitors are a new therapeutic option for urothelial carcinoma (UC) with FGFR2/3 alterations. In this study, we analyzed genetic alterations, co-regulation, and differential expression for 45 genes encoding FGF, FGFR, or FGF-binding proteins (FGFBPs) in five published UC cohorts (n = 3939 MIBC) and 39 UC cell lines (DepMap portal). Network analyses identified FGFR1/3 genes as critical oncogenic hubs, co-regulated with their ligands and co-receptors, and abundantly expressed at protein level in the HPA immunohistochemistry data set. Machine learning with 38 FGFR-, FGF-, and FGFBP-coding transcripts reproduced consensus molecular subtypes with high accuracy of 0.72-0.84 (Cohen's κ 0.59-0.77). FGFR3 mutations in the transmembrane/hinge region, which were enriched in luminal papillary tumors, trigger ligand-independent signaling. Conversely, overexpression of FGFR1 and its ligands and accessory protein transcripts indicates ligand-dependent FGFR1 signaling in stroma-rich and basal/squamous subtypes. The sensitivity of most DepMap UC cell lines to pan-FGFR inhibitors in the GDSC and PRISM drug screens was independent of FGFR3 alterations. In vitro, erdafitinib reduced proliferation in FGFR wild-type UC cell lines in a similar manner to FGFR3-mutated cell lines. Our findings highlight FGFR1 and FGFR3 as pivotal signaling pathways with distinct, molecular subtype-specific activation mechanisms. The results suggest that FGFR inhibitors may have therapeutic applications beyond UC tumors with FGFR2/3 alterations. Show less

FGFR3 mutations are among the most frequent genomic alterations in urothelial cancer (UC) being mainly associated with the luminal papillary (LumP) subtype. With the establishment of fibroblast growth factor receptor (FGFR) inhibitors, the treatment of UC is now shifting more and more towards personalized medicine. A systematic review using Medline and scientific meeting records was carried out according to the Preferred Reporting Items for Systematic Review and Meta-analyses guidelines to assess the potential role of FGFR inhibitors in combination with additional therapies for the management of UC. Ongoing trials were identified via a systematic search on ClinicalTrials.gov. A total of eleven full-text papers, ten congress abstracts, and 5 trials on ClinicalTrials.gov were identified. Following the BLC2001 and THOR study, erdafitinib is the only approved FGFR1-4 inhibitor for metastatic UC with susceptible FGFR2/3 alterations following platinum-based chemotherapy. According to the THOR data of cohort 2, erdafitinib should not be recommended in patients who are eligible for and have not received prior immune checkpoint inhibitors (ICIs). One phase 3 trial is currently evaluating the intravesical device system (TAR210) in FGFR-altered intermediate non-muscle invasive bladder cancer (MoonRISe-1). Preclinical evidence suggests that combination-based approaches could be considered to improve the efficacy of FGFR inhibitors in patients with UC. Nine phase 1b/2 trials are focusing on the combination of FGFR inhibitors with ICIs, chemotherapy, or enfortumab vedotin. In metastatic disease, some preliminary analyses have reported promising results from these combinations (e.g. NORSE and FORT-2 trial). However, no phase 3 trial is terminated, so there is currently no level 1 evidence with long-term outcomes to support the combination of FGFR inhibitors with ICIs, chemotherapy, or targeted therapies. A better understanding of the different mechanisms of action to inhibit FGFR signaling pathways, optimal patient selection and treatment approaches is still needed. Show less

Several studies have indicated that broad genomic characterization of childhood cancer provides diagnostically and/or therapeutically relevant information in selected high-risk cases. However, the extent to which such characterization offers clinically actionable data in a prospective broadly inclusive setting remains largely unexplored. We implemented prospective whole-genome sequencing (WGS) of tumor and germline, complemented by whole-transcriptome sequencing (RNA-Seq) for all children diagnosed with a primary or relapsed solid malignancy in Sweden. Multidisciplinary molecular tumor boards were set up to integrate genomic data in the clinical decision process along with a medicolegal framework enabling secondary use of sequencing data for research purposes. During the study's first 14 months, 118 solid tumors from 117 patients were subjected to WGS, with complementary RNA-Seq for fusion gene detection in 52 tumors. There was no significant geographic bias in patient enrollment, and the included tumor types reflected the annual national incidence of pediatric solid tumor types. Of the 112 tumors with somatic mutations, 106 (95%) exhibited alterations with a clear clinical correlation. In 46 of 118 tumors (39%), sequencing only corroborated histopathological diagnoses, while in 59 cases (50%), it contributed to additional subclassification or detection of prognostic markers. Potential treatment targets were found in 31 patients (26%), most commonly Up-front, large-scale genomic characterization of pediatric solid malignancies provides diagnostically valuable data in the majority of patients also in a largely unselected cohort. Show less

The binding of lipoprotein lipase (LPL) to GPIHBP1 focuses the intravascular hydrolysis of triglyceride-rich lipoproteins on the surface of capillary endothelial cells. This process provides essential lipid nutrients for vital tissues (e.g., heart, skeletal muscle, and adipose tissue). Deficiencies in either LPL or GPIHBP1 impair triglyceride hydrolysis, resulting in severe hypertriglyceridemia. The activity of LPL in tissues is regulated by angiopoietin-like proteins 3, 4, and 8 (ANGPTL). Dogma has held that these ANGPTLs inactivate LPL by converting LPL homodimers into monomers, rendering them highly susceptible to spontaneous unfolding and loss of enzymatic activity. Here, we show that binding of an LPL-specific monoclonal antibody (5D2) to the tryptophan-rich lipid-binding loop in the carboxyl terminus of LPL prevents homodimer formation and forces LPL into a monomeric state. Of note, 5D2-bound LPL monomers are as stable as LPL homodimers (i.e., they are not more prone to unfolding), but they remain highly susceptible to ANGPTL4-catalyzed unfolding and inactivation. Binding of GPIHBP1 to LPL alone or to 5D2-bound LPL counteracts ANGPTL4-mediated unfolding of LPL. In conclusion, ANGPTL4-mediated inactivation of LPL, accomplished by catalyzing the unfolding of LPL, does not require the conversion of LPL homodimers into monomers. Thus, our findings necessitate changes to long-standing dogma on mechanisms for LPL inactivation by ANGPTL proteins. At the same time, our findings align well with insights into LPL function from the recent crystal structure of the LPL•GPIHBP1 complex. Show less

Pituitary adenomas are among the most frequent intracranial neoplasms and treatment depends on tumor subtype and clinical features. Unfortunately, non responder cases occur, then new molecular targets are needed. Notch system component expression and activation data are scarce in pituitary tumorigenesis, we therefore aimed to characterize Notch system in pituitary tumors of different histotype. In human pituitary adenomas we showed Show less

Chondrosarcoma is a malignant bone tumor that is often resistant to chemotherapy and radiotherapy. We applied high resolution oligonucleotide array comparative genomic hybridization to 46 tumor specimens from 44 patients with chondrosarcoma and identified several genes with potential importance for the development of chondrosarcoma. Several homozygous deletions were detected. The tumor suppressor genes CDKN2A and MTAP were each homozygously deleted in four of the cases, and the RB1 gene was homozygously deleted in one. Two homozygous deletions of MTAP did not affect CDKN2A. Deletions were also found to affect genes of the cadherin family, including CDH4 and CDH7, each of which had a targeted homozygous loss in one case, and CDH19, which had a targeted homozygous loss in two cases. Loss of the EXT1 and EXT2 genes was uncommon; EXT1 was homozygously deleted in none and EXT2 in two of the cases, and large heterozygous losses including EXT1 and/or EXT2 were seen in three cases. Targeted gains and amplifications affected the MYC, E2F3, CDK6, PDGFRA, KIT, and PDGFD genes in one case each. The data indicate that chondrosarcomas develop through a combination of genomic imbalances that often affect the RB1 signaling pathway. The inactivation of cadherin genes may also be critical in the pathogenesis of the tumor. Show less

An acceleration of differentiation, at the expense of proliferation, is observed after exposure of various biological models to low frequency and low amplitude electric and electromagnetic fields. Following these results showing significant modifications, we try to identify the biological mechanism involved at the cell level through microarray screening. For this study, we use epidermis cultures harvested from human abdominoplasty. Two platinum electrodes are used to apply the electric signal. The gene expressions of 38,500 well-characterized human genes are analyzed using Affymetrix(®) microarray U133 Plus 2.0 chips. The protocol is repeated on three different patients. After three periods of exposure, a total of 24 chips have been processed. After the application of ELF electric fields, the microarray analysis confirms a modification of the gene expression of epidermis cells. Particularly, four up-regulated genes (DKK1, TXNRD1, ATF3, and MME) and one down-regulated gene (MACF1) are involved in the regulation of proliferation and differentiation. Expression of these five genes was also confirmed by real-time rtPCR in all samples used for microarray analysis. These results corroborate an acceleration of cell differentiation at the expense of cell proliferation. Show less

Hypertriglyceridemia and fatty liver are common in patients with type 2 diabetes, but the factors connecting alterations in glucose metabolism with plasma and liver lipid metabolism remain unclear. Apolipoprotein CIII (apoCIII), a regulator of hepatic and plasma triglyceride metabolism, is elevated in type 2 diabetes. In this study, we analyzed whether apoCIII is affected by altered glucose metabolism. Liver-specific insulin receptor-deficient mice display lower hepatic apoCIII mRNA levels than controls, suggesting that factors other than insulin regulate apoCIII in vivo. Glucose induces apoCIII transcription in primary rat hepatocytes and immortalized human hepatocytes via a mechanism involving the transcription factors carbohydrate response element-binding protein and hepatocyte nuclear factor-4α. ApoCIII induction by glucose is blunted by treatment with agonists of farnesoid X receptor and peroxisome proliferator-activated receptor-α but not liver X receptor, ie, nuclear receptors controlling triglyceride metabolism. Moreover, in obese humans, plasma apoCIII protein correlates more closely with plasma fasting glucose and glucose excursion after oral glucose load than with insulin. Glucose induces apoCIII transcription, which may represent a mechanism linking hyperglycemia, hypertriglyceridemia, and cardiovascular disease in type 2 diabetes. Show less

Histologic grade is currently the best predictor of clinical course in chondrosarcoma patients. Grading suffers, however, from extensive interobserver variability and new objective markers are needed. Hence, we have investigated DNA copy numbers in chondrosarcomas with the purpose of identifying markers useful for prognosis and subclassification. The overall pattern of genomic imbalances was assessed in a series of 67 chondrosarcomas using array comparative genomic hybridization. Statistical analyses were applied to evaluate the significance of alterations detected in subgroups based on clinical data, morphology, grade, tumor size, and karyotypic features. Also, the global gene expression profiles were obtained in a subset of the tumors. Genomic imbalances, in most tumors affecting large regions of the genome, were found in 90% of the cases. Several apparently distinctive aberrations affecting conventional central and peripheral tumors, respectively, were identified. Although rare, recurrent amplifications were found at 8q24.21-q24.22 and 11q22.1-q22.3, and homozygous deletions of loci previously implicated in chondrosarcoma development affected the CDKN2A, EXT1, and EXT2 genes. The chromosomal imbalances in two distinct groups of predominantly near-haploid and near-triploid tumors, respectively, support the notion that polyploidization of an initially hyperhaploid/hypodiploid cell population is a common mechanism of chondrosarcoma progression. Increasing patient age as well as tumor grade were associated with adverse outcome, but no copy number imbalance affected metastasis development or tumor-associated death. Despite similarities in the overall genomic patterns, the present findings suggest that some regions are specifically altered in conventional central and peripheral tumors, respectively. Show less