Neoplasms associated with alterations in fibroblast growth factor receptors

Thalidomide and Its Analogs Differentially Target Fibroblast Growth Factor Receptors: Thalidomide Suppresses FGFR Gene Expression while Pomalidomide Dampens FGFR2 Activity

Thalidomide is an infamous teratogen and it is continuously being explored for its anticancer properties. Fibroblast growth factor receptors (FGFRs) are implicated in embryo development and cancer pathophysiology. With striking similarities observed between FGFR implicated conditions and thalidomide embryopathy, we hypothesized thalidomide targets FGFRs. We utilized three different cell lines and chicken embryo model to investigate the effects of thalidomide and analogs on FGFR expression. We performed molecular docking, KINOMEscan analysis, and kinase activity assays to study the drug-protein interactions. The expression of FGFR1 and FGFR2 was differentially regulated by all the three drugs in cells as well as in developing organs. Transcriptome analysis of thalidomide-treated chick embryo strongly suggests the modulation of FGFR signaling and key transcription factors. Corroboration with previous studies suggests that thalidomide might affect FGFR expression through the transcription factor, E2F1. At the protein level, molecular docking predicted all three analogs to interact with lysine residue at 517th and 508th positions of FGFR2 and FGFR3, respectively. This lysine coordinates the ATP binding site of FGFR, thus hinting at the possible perturbation of FGFR activity by thalidomide. Kinome analysis revealed that kinase activities of FGFR2 and FGFR3 (G697C) reduced by 31% and 65%, respectively, in the presence of 10 μM thalidomide. Further, we checked and confirmed that the analogs inhibited the FGFR2 kinase activity in a dose-dependent manner. This study suggests that FGFRs could be potential targets of thalidomide and the two analogs, and also endorses the link between the teratogenicity and antitumor activities of the drugs.

Fibroblast growth factor receptor signaling in hereditary and neoplastic disease: biologic and clinical implications

Fibroblast growth factors (FGFs) and their receptors (FGFRs) are transmembrane growth factor receptors with wide tissue distribution. FGF/FGFR signaling is involved in neoplastic behavior and also development, differentiation, growth, and survival. FGFR germline mutations (activating) can cause skeletal disorders, primarily dwarfism (generally mutations in FGFR3), and craniofacial malformation syndromes (usually mutations in FGFR1 and FGFR2); intriguingly, some of these activating FGFR mutations are also seen in human cancers. FGF/FGFR aberrations reported in cancers are mainly thought to be gain-of-function changes, and several cancers have high frequencies of FGFR alterations, including breast, bladder, or squamous cell carcinomas (lung and head and neck). FGF ligand aberrations (predominantly gene amplifications) are also frequently seen in cancers, in contrast to hereditary syndromes. There are several pharmacologic agents that have been or are being developed for inhibition of FGFR/FGF signaling. These include both highly selective inhibitors as well as multi-kinase inhibitors. Of note, only four agents (ponatinib, pazopanib, regorafenib, and recently lenvatinib) are FDA-approved for use in cancer, although the approval was not based on their activity against FGFR. Perturbations in the FGFR/FGF signaling are present in both inherited and malignant diseases. The development of potent inhibitors targeting FGF/FGFR may provide new tools against disorders caused by FGF/FGFR alterations.

Ligands to FGF receptor 2-IIIb induce proliferation, motility, protection from cell death and cytoskeletal rearrangements in epithelial ovarian cancer cell lines

Epithelial ovarian cancer (EOC) is the most common and lethal form of gynecological malignancy. These cancers are thought to be derived from the ovarian surface epithelium (OSE). We have previously reported that the epithelial-specific FGF receptor 2 splice variant IIIb is not expressed in normal OSE, but is expressed in approximately 80% of EOCs. We have examined the phenotypic effects of ligands to FGF receptor 2-IIIb, namely FGFs 1,7 and 10, on a panel of EOC cell lines. We show that these ligands increase cell viability, induce DNA synthesis, motility and chemotaxis and protect from spontaneous cell death when EOC cells are maintained in serum free medium. A blocking antiserum to FGF-7 reduces viability of 41-M EOC cells, and abrogates the ability of ascitic fluid containing FGF-7 to induce DNA synthesis in these cells. Finally, we show that FGF-7 can induce a reorganization of the actin cytoskeleton in SK-OV-3 ovarian cancer cells. It is suggested that ligands to FGF receptor 2-IIIb affect a range of phenotypes important in the neoplastic growth of EOCs.

Fibroblast growth factor receptor 2, gain-of-function mutations, and tumourigenesis: investigating a potential link

Activating germline mutations in the fibroblast growth factor receptor (FGFR) gene family have been identified in several dominantly inherited skeletal disorders; in the case of FGFR3, the same somatically arising mutations have also been isolated from a variety of tumour tissues. Whilst the role of FGFR2 mutations in congenital syndromes has been well documented, their relationship with cancer has not been clearly defined. Based on evidence that gain-of-function mutations in FGFR2 drive positive selection in adult spermatogonia, the present study investigated, by denaturing high-performance liquid chromatography (DHPLC), DNA sequencing, and restriction digestion, the prevalence of FGFR2 mutations in 58 tumour cell lines of various types, and 29 testicular germ cell tumour samples. Although sequence variations and allelic imbalance were identified in FGFR2, none of the previously documented dominant mutations was detected in any of the tumour types examined. This suggests that gain-of-function FGFR2 mutations are not commonly encountered in tumourigenesis and specifically excludes a major contribution in testicular tumours.

Molecular dimensions of gastrointestinal tumors: some thoughts for digestion

Topics discussed here include PTEN mutations and colonic polyps; WNT signaling, APC, beta-catenin, and gastrointestinal neoplasms; mismatch-repair genes (MLH1, MSH2, PMS1, MSH6) and hereditary nonpolyposis colorectal cancer; MYH mutations and autosomal recessive colorectal tumors; STK11 mutations and Peutz-Jeghers syndrome; TGFbeta and gastrointestinal cancer; BMPR1A mutations and juvenile polyposis; FGF/FGFR alterations in gastrointestinal neoplasms; PTCH mutations and gastrointestinal neoplasms; RUNX3 expression and gastric cancer; role of mucins in gastric carcinogenesis; KIT, PDGFRalpha, and gastrointestinal stromal tumors; intestinal neurofibromatosis; and gastrointestinal tumors in other disorders.