Targeting of Ras-mediated FGF signaling suppresses Pten-deficient skin tumor

Formation of benign tumors by stem cell deregulation

Within living organisms, stem cells respond to various cues, including to niche signals and growth factors. Niche signals originate from the stem cell's microenvironment and promote the undifferentiated state by preventing differentiation, allowing for stem cell self-renewal. On the other hand, growth factors promote stem cell growth and proliferation, while their sources comprise of a systemic input reflecting the animal's nutritional and metabolic status, and a localized, homeostatic feedback signal from the tissue that the stem cells serve. That homeostatic signal prevents unnecessary stem cell proliferation when the corresponding differentiated tissues already have optimal cell contents. Here, we recapitulate progresses made in our understanding of in vivo stem cell regulation, largely using simple models, and draw the conclusion that 2 types of stem cell deregulations can provoke the formation of benign tumors. Namely, constitutive niche signaling promotes the formation of undifferentiated "stem cell" tumors, while defective homeostatic signaling leads to the formation of differentiated tumors. Finally, we provide evidence that these general principles may be conserved in mammals and as such, may underlie benign tumor formation in humans, while benign tumors can evolve into cancer.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

Fibroblast growth factor receptor signalling dysregulation and targeting in breast cancer

Fibroblast Growth Factor Receptor (FGFR) signalling plays a critical role in breast embryonal development, tissue homeostasis, tumorigenesis and metastasis. FGFR, its numerous FGF ligands and signalling partners are often dysregulated in breast cancer progression and are one of the causes of resistance to treatment in breast cancer. Furthermore, FGFR signalling on epithelial cells is affected by signals from the breast microenvironment, therefore increasing the possibility of breast developmental abnormalities or cancer progression. Increasing our understanding of the multi-layered roles of the complex family of FGFRs, their ligands FGFs and their regulatory partners may offer novel treatment strategies for breast cancer patients, as a single agent or rational co-target, which will be explored in depth in this review.

The role of microRNAs in diseases and related signaling pathways

MicroRNAs (miRNAs) are epigenetic regulators of the gene expression and act through posttranslational modification. They bind to 3'-UTR of target mRNAs to inhibit translation or increase the degradation mRNA in many tissues. Any alteration in the level of miRNA expression in many human diseases indicates their involvement in the pathogenesis of many diseases. On the other hand, the regulation of the signaling pathways is necessary for the maintenance of natural and physiological characteristics of any cell. It is worth mentioning that dysfunction of the signaling pathways manifests itself as a disorder or disease. The significant evidence report that miRNAs regulate the several signaling pathways in many diseases. Base on previous studies, miRNAs can be used for therapeutic or diagnostic purposes. According to the important role of miRNAs on the cell signaling pathways, this article reviews miRNAs involvement in incidence of diseases by changing signaling pathways.

FGF2 disruption enhances thermogenesis in brown and beige fat to protect against adiposity and hepatic steatosis

Objective

Fibroblast growth factor 2 (FGF2) has been reported to play divergent roles in white adipogenic differentiation, however, whether it regulates thermogenesis of fat tissues remains largely unknown. We therefore aimed to investigate the effect of FGF2 on fat thermogenesis and elucidate the underlying mechanisms.

Methods

FGF2-KO and wild-type (WT) mice were fed with chow diet and high-fat diet (HFD) for 14 weeks. The brown and white fat mass, thermogenic capability, respiratory exchange ratio, and hepatic fat deposition were determined. In vitro experiments were conducted to compare the thermogenic ability of FGF2-KO- with WT-derived brown and white adipocytes. Exogenous FGF2 was supplemented to in vitro-cultured WT brown and ISO-induced beige adipocytes. The FGFR inhibitor, PPARγ agonist, and PGC-1α expression lentivirus were used with the aid of technologies including Co-IP, ChIP, and luciferase reporter assay to elucidate the mechanisms underlying the FGF2 regulation of thermogenesis.

Results

FGF2 gene disruption results in increased thermogenic capability in both brown and beige fat, supporting by increased UCP1 expression, enhanced respiratory exchange ratio, and elevated thermogenic potential in response to cold exposure. Thus, the deletion of FGF2 protects mice from high fat-induced adiposity and hepatic steatosis. Mechanistically, in vitro investigations indicated FGF2 acts in autocrine/paracrine fashions. Exogenous FGF2 supplementation inhibits both PGC-1α and PPARγ expression, leading to suppression of UCP1 expression in brown and beige adipocytes.

Conclusions

These findings demonstrate that FGF2 is a novel thermogenic regulator, suggesting a viable potential strategy for using FGF2-selective inhibitors in combat adiposity and associated hepatic steatosis.

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FGF2-KO mice show potentiated stimulation on thermogenic capability under both basal and cold challenge stimulation.

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FGF2 disruption protected mice against HFD-induced adiposity and hepatic steatosis.

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FGF2 acts in autocrine/paracrine fashions in vitro.

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Both PPARγ and PGC-1α play roles in FGF2 suppression of thermogenesis.

Lacrimal gland budding requires PI3K-dependent suppression of EGF signaling

The patterning of epithelial buds is determined by the underlying signaling network. Here, we study the cross-talk between phosphoinositide 3-kinase (PI3K) and Ras signaling during lacrimal gland budding morphogenesis. Our results show that PI3K is activated by both the p85-mediated insulin-like growth factor (IGF) and Ras-mediated fibroblast growth factor (FGF) signaling. On the other hand, PI3K also promotes extracellular signal-regulated kinase (ERK) signaling via a direct interaction with Ras. Both PI3K and ERK are upstream regulators of mammalian target of rapamycin (mTOR), and, together, they prevent expansion of epidermal growth factor (EGF) receptor expression from the lacrimal gland stalk to the bud region. We further show that this suppression of EGF signaling is necessary for induction of lacrimal gland buds. These results reveal that the interplay between PI3K, mitogen-activated protein kinase, and mTOR mediates the cross-talk among FGF, IGF, and EGF signaling in support of lacrimal gland development.

Design and Synthesis of Biotinylated Bivalent Carboline Derivatives as Potent Antitumor Agents

Compound 6, a novel β-carboline comprising two 1-methyl-9H-β-carboline-3-carboxylic acids and a biotin moiety conjugated together using tris(2-aminoethyl)amine, was synthesized and tested for its cytotoxicity toward MCF-7 and HepG2 cell lines and antitumor potency in an S180 tumor-bearing mouse model. Compound 6 was delivered via biotin receptor-mediated endocytosis and exerted its therapeutic effects by intercalation binding with DNA. In vivo antitumor evaluations of 6 revealed that it is efficacious and exhibits low systemic toxicity.

The Hippo pathway integrates PI3K-Akt signals with mechanical and polarity cues to control tissue growth

The Hippo signalling pathway restricts cell proliferation in animal tissues by inhibiting Yes-associated protein (YAP or YAP1) and Transcriptional Activator with a PDZ domain (TAZ or WW-domain-containing transcriptional activator [WWTR1]), coactivators of the Scalloped (Sd or TEAD) DNA-binding transcription factor. Drosophila has a single YAP/TAZ homolog named Yorkie (Yki) that is regulated by Hippo pathway signalling in response to epithelial polarity and tissue mechanics during development. Here, we show that Yki translocates to the nucleus to drive Sd-mediated cell proliferation in the ovarian follicle cell epithelium in response to mechanical stretching caused by the growth of the germline. Importantly, mechanically induced Yki nuclear localisation also requires nutritionally induced insulin/insulin-like growth factor 1 (IGF-1) signalling (IIS) via phosphatidyl inositol-3-kinase (PI3K), phosphoinositide-dependent kinase 1 (PDK1 or PDPK1), and protein kinase B (Akt or PKB) in the follicular epithelium. We find similar results in the developing Drosophila wing, where Yki becomes nuclear in the mechanically stretched cells of the wing pouch during larval feeding, which induces IIS, but translocates to the cytoplasm upon cessation of feeding in the third instar stage. Inactivating Akt prevents nuclear Yki localisation in the wing disc, while ectopic activation of the insulin receptor, PI3K, or Akt/PKB is sufficient to maintain nuclear Yki in mechanically stimulated cells of the wing pouch even after feeding ceases. Finally, IIS also promotes YAP nuclear localisation in response to mechanical cues in mammalian skin epithelia. Thus, the Hippo pathway has a physiological function as an integrator of epithelial cell polarity, tissue mechanics, and nutritional cues to control cell proliferation and tissue growth in both Drosophila and mammals.

Fibroblast Growth Factor Receptor Signaling in Skin Cancers

Fibroblast growth factor (FGF)/Fibroblast growth factor receptor (FGFR) signaling regulates various cellular processes during the embryonic development and in the adult organism. In the skin, fibroblasts and keratinocytes control proliferation and survival of melanocytes in a paracrine manner via several signaling molecules, including FGFs. FGF/FGFR signaling contributes to the skin surface expansion in childhood or during wound healing, and skin protection from UV light damage. Aberrant FGF/FGFR signaling has been implicated in many disorders, including cancer. In melanoma cells, the FGFR expression is low, probably because of the strong endogenous mutation-driven constitutive activation of the downstream mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK-ERK) signaling pathway. FGFR1 is exceptional as it is expressed in the majority of melanomas at a high level. Melanoma cells that acquired the capacity to synthesize FGFs can influence the neighboring cells in the tumor niche, such as endothelial cells, fibroblasts, or other melanoma cells. In this way, FGF/FGFR signaling contributes to intratumoral angiogenesis, melanoma cell survival, and development of resistance to therapeutics. Therefore, inhibitors of aberrant FGF/FGFR signaling are considered as drugs in combination treatment. The ongoing LOGIC-2 phase II clinical trial aims to find out whether targeting the FGF/FGFR signaling pathway with BGJ398 may be a good therapeutic strategy in melanoma patients who develop resistance to v-Raf murine sarcoma viral oncogene homolog B (BRAF)/MEK inhibitors.

Deciphering role of FGFR signalling pathway in pancreatic cancer

Recently, fibroblast growth factors are identified to play a vital role in the development and progression of human pancreatic cancer. FGF pathway is critical involved in numerous cellular processes through regulation of its downstream targets, including proliferation, apoptosis, migration, invasion, angiogenesis and metastasis. In this review article, we describe recent advances of FGFR signalling pathway in pancreatic carcinogenesis and progression. Moreover, we highlight the available chemical inhibitors of FGFR pathway for potential treatment of pancreatic cancer. Furthermore, we discuss whether targeting FGFR pathway is a novel therapeutic strategy for pancreatic cancer clinical management.