Targeting Cellular Trafficking of Fibroblast Growth Factor Receptors as a Strategy for Selective Cancer Treatment

Fibroblast growth factor receptors (FGFRs) in response to fibroblast growth factors (FGFs) transmit signals across the cell membrane, regulating important cellular processes, like differentiation, division, motility, and death. The aberrant activity of FGFRs is often observed in various diseases, especially in cancer. The uncontrolled FGFRs' function may result from their overproduction, activating mutations, or generation of FGFRs' fusion proteins. Besides their typical subcellular localization on the cell surface, FGFRs are often found inside the cells, in the nucleus and mitochondria. The intracellular pool of FGFRs utilizes different mechanisms to facilitate cancer cell survival and expansion. In this review, we summarize the current stage of knowledge about the role of FGFRs in oncogenic processes. We focused on the mechanisms of FGFRs' cellular trafficking-internalization, nuclear translocation, and mitochondrial targeting, as well as their role in carcinogenesis. The subcellular sorting of FGFRs constitutes an attractive target for anti-cancer therapies. The blocking of FGFRs' nuclear and mitochondrial translocation can lead to the inhibition of cancer invasion. Moreover, the endocytosis of FGFRs can serve as a tool for the efficient and highly selective delivery of drugs into cancer cells overproducing these receptors. Here, we provide up to date examples how the cellular sorting of FGFRs can be hijacked for selective cancer treatment.

Differential regulation of fibroblast growth factor receptor 1 trafficking and function by extracellular galectins

Fibroblast growth factor receptors (FGFRs) are integral membrane proteins that transmit signals through the plasma membrane. FGFRs signaling needs to be precisely adjusted as aberrant FGFRs function is associated with development of human cancers or severe metabolic diseases. The subcellular localization, trafficking and function of FGFRs rely on the formation of multiprotein complexes. In this study we revealed galectins, lectin family members implicated in cancer development and progression, as novel FGFR1 binding proteins. We demonstrated that galectin-1 and galectin-3 directly bind to the sugar chains of the glycosylated extracellular part of FGFR1. Although both galectins compete for the same binding sites on FGFR1, these proteins elicit different impact on FGFR1 function and cellular trafficking. Galectin-1 mimics fibroblast growth factor as it efficiently activates FGFR1 and receptor-downstream signaling pathways that result in cell proliferation and apoptotic evasion. In contrast, galectin-3 induces extensive clustering of FGFR1 on the cell surface that inhibits constitutive internalization of FGFR1. Our data point on the interplay between extracellular galectins and FGFRs in the regulation of cell fate.