👤 Katarzyna Dominika Sluzalska

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

Targeting fibroblast growth factor receptor 1 (FGFR1) is a promising therapeutic strategy for various cancers associated with alterations in the FGFR1 gene. In this study, we developed a highly cytotoxic bioconjugate based on fibroblast growth factor 2 (FGF2), which is a natural ligand of this receptor, and two potent cytotoxic drugs-α-amanitin and monomethyl auristatin E-with completely independent mechanistic modes of action. Utilizing recombinant DNA technology, we produced an FGF2 N- to C-end dimer that exhibited superior internalization capacity in FGFR1-positive cells. The drugs were site-specifically attached to the targeting protein using SnoopLigase- and evolved sortase A-mediated ligations. The resulting dimeric dual-warhead conjugate selectively binds to the FGFR1 and utilizes receptor-mediated endocytosis to enter the cells. Moreover, our results demonstrate that the developed conjugate exhibits about 10-fold higher cytotoxic potency against FGFR1-positive cell lines than an equimolar mixture of single-warhead conjugates. The diversified mode of action of the dual-warhead conjugate may help to overcome the potential acquired resistance of FGFR1-overproducing cancer cells to single cytotoxic drugs. Show less