👤 Jenny Ormanns

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

Fish of the genus Xiphophorus provide a prominent example of genetic control of male body size and reproductive tactics. In X.nigrensis and X.multilineatus, puberty onset and body length are determined by melanocortin 4 receptor (Mc4r) allelic and copy number variations which were proposed to fine-tune the signaling output of the system. Accessory protein Mrap2 is required for growth across species by affecting Mc4r signaling. The molecular mechanism how Mc4r signaling controls puberty regulation in Xiphophorus and whether the interaction with Mrap2 is also involved was so far unclear. Hence, we examined Mc4r and Mrap2 in X.nigrensis and X.multilineatus, in comparison to a more distantly related species, X.hellerii. mc4r and mrap2 transcripts co-localized in the hypothalamus and preoptic regions in large males, small males and females of X.nigrensis, with similar signal strength for mrap2 but higher expression of mc4r in large males. This overexpression is constituted by wild-type and one subtype of mutant alleles. In vitro studies revealed that Mrap2 co-expressed with Mc4r increased cAMP production but did not change EC50. Cells co-expressing the wild-type and one mutant allele showed lower cAMP signaling than Mc4r wild-type cells. This indicates a role of Mc4r alleles, but not Mrap2, in puberty signaling. Different from X.nigrensis and X.multilineatus, X.hellerii has only wild-type alleles, but also shows a puberty onset and body length polymorphism, despite the absence of mutant alleles. Like in the two other species, mc4r and mrap2 transcripts colocalized and mc4r is expressed at substantially higher levels in large males. This demonstrates that puberty and growth regulation mechanism may not be identical even within same genus. Show less