👤 Klara Zakrzewska

While the plasma phylloquinone (PK) concentration is inversely correlated with cardiovascular risk, the involvement of PK in regulating endothelial function has not been directly investigated. Therefore, in this study we assessed the effects of short-term treatment with PK-deficient diets (5-10 weeks) on endothelial function in normolipidemic 14-week-old male C57BL/6JCmd mice and age-matched dyslipidaemic male E3L.CETP mice. Our results show that in normolipidemic mice dietary PK deficiency was associated with a marked reduction of PK levels in the plasma and liver (liquid chromatography-mass spectrometry measurements) and with impaired endothelium-dependent vasodilation assessed in vivo by magnetic resonance imaging (MRI). Dietary PK deficiency-induced endothelial dysfunction was fully reversed by PK supplementation. In dyslipidaemic E3L.CETP mice, dietary PK deficiency exacerbated preexisting endothelial dysfunction. Furthermore, dietary PK deficiency decreased menaquinone-4 (MK-4) levels in the aorta but did not affect blood coagulation (calibrated automated thrombography), microbiota composition (culturing and next-generation sequencing), and gut menaquinone production. In conclusion, our study demonstrated for the first time that sufficient dietary PK intake supports endothelial function in normolipidemic and dyslipidaemic mice indicating nutritional significance of dietary PK in the maintenance of endothelial function in humans. Show less

Impaired fibroblast growth factor receptor (FGFR) signaling is associated with many human conditions, including growth disorders, degenerative diseases, and cancer. Current FGFR therapeutics are based on chemical inhibitors of FGFR tyrosine kinase activity (TKIs). However, FGFR TKIs are limited in their target specificity as they generally inhibit all FGFRs and other receptor tyrosine kinases. In the search for specific inhibitors of human FGFR1, we identified VZ23, a DNA aptamer that binds to FGFR1b and FGFR1c with a K Show less

Chemoresistance of cancer cells, resulting from various mechanisms, is a significant obstacle to the effectiveness of modern cancer therapies. Targeting fibroblast growth factors (FGFs) and their receptors (FGFRs) is becoming crucial, as their high activity significantly contributes to cancer development and progression by driving cell proliferation and activating signaling pathways that enhance drug resistance. We investigated the potential of honokiol and FGF ligand trap in blocking the FGF1/FGFR1 axis to counteract drug resistance. Using PEAQ-ITC, we verified direct interaction of honokiol with the FGFR1 kinase domain. We then demonstrated the effect of FGF1/FGFR1 inhibition on taltobulin resistance in cells expressing FGFR1. Finally, we generated drug-resistant clones by prolonged exposure of cells with negligible FGFR levels to taltobulin alone, taltobulin and honokiol, or taltobulin and FGF ligand trap. We demonstrated for the first time a direct interaction of honokiol with the FGFR1 kinase domain, resulting in inhibition of downstream signaling pathways. We revealed that both honokiol and FGF ligand trap prevent FGF1-dependent protection against taltobulin in cancer cells expressing FGFR1. In addition, we showed that cells obtained by long-term exposure to taltobulin are resistant to both taltobulin and other microtubule-targeting drugs, and exhibit elevated levels of FGFR1 and cyclin D. We also found that the presence of FGF-ligand trap prevents the development of long-term resistance to taltobulin. Our results shed light on how blocking the FGF1/FGFR1 axis by honokiol and FGF ligand trap could help develop more effective cancer therapies, potentially preventing the emergence of drug-resistant relapses. Show less

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. Show less

FGF homologous factors (FHFs) are the least described group of fibroblast growth factors (FGFs). The FHF subfamily consists of four proteins: FGF11, FGF12, FGF13, and FGF14. Until recently, FHFs were thought to be intracellular, non-signaling molecules, despite sharing structural and sequence similarities with other members of FGF family that can be secreted and activate cell signaling by interacting with surface receptors. Here, we show that despite lacking a canonical signal peptide for secretion, FHFs are exported to the extracellular space. Furthermore, we propose that their secretion mechanism is similar to the unconventional secretion of FGF2. The secreted FHFs are biologically active and trigger signaling in cells expressing FGF receptors (FGFRs). Using recombinant proteins, we demonstrated their direct binding to FGFR1, resulting in the activation of downstream signaling and the internalization of the FHF-FGFR1 complex. The effect of receptor activation by FHF proteins is an anti-apoptotic response of the cell. Show less

Molecular alterations in tumor-adjacent tissues have recently been recognized in some types of cancer. This phenomenon has not been studied in endometrial cancer. We aimed to analyze the expression of genes associated with cancer progression and metabolism in primary endometrial cancer samples and the matched tumor-adjacent tissues and in the samples of endometria from cancer-free patients with uterine leiomyomas. Paired samples of tumor-adjacent tissues and primary tumors from 49 patients with endometrial cancer (EC), samples of endometrium from 25 patients with leiomyomas of the uterus, and 4 endometrial cancer cell lines were examined by the RT-qPCR, for Show less

Embryonal tumors, the most common group of malignant brain tumors in childhood, are heterogeneous and have been associated with a large number of genetic abnormalities. The aim of this study was to comprehensively analyze loss of heterozygosity (LOH) on regions harboring suppressor genes (PTCH2, PTCH1, APC, PTEN, DMBT1, SUFU, AXIN1, hSNF5/INI1) and to study chromosomal regions in which deletions have been described most frequently (1p, 1q, 11p, 16p, 17p). Twenty-nine children (17 male and 12 female), aged from 1 year 13 years were included in this study. There were 24 medulloblastomas (MB) and 5 supratentorial primitive neuroectodermal tumors (sPNET). Tissue samples from 29 primary and 11 recurrent tumors were analyzed according to the LOH standard procedures, which were extended to include fluorescence in situ hybridization for detection of isochromosome 17q (i(17q)) and direct sequencing ofTP53 exon 4. LOH on 17p was found in 15 out of 29 tumors. FISH analysis identified the presence of i(17q) in 16 tumors. Comparison of LOH analysis and the FISH data indicated that alterations of 17p were related to be the introduction of an i(17q) formation. LOH on 10q and 9q was observed in 4 and 2 cases, respectively, and was associated with alterations of chromosome 17. These results indicated a connection between alterations of PTCH/SHH genes and abnormalities of chromosome 17. A deleted region on 22q, covering the hSNF5/INI1 locus, was observed in 3 tumors. Progression of the molecular changes occurred in 1 case of recurrent medulloblastoma. LOH on 10q and 17p was found in both primary and recurrent tumor, while losses on 11p, 16p, and 16q occurred only in the recurrent tumor. No evidence of alteration in TP53 exon 4 was identified. Show less