The role of IL-1ß and TNF-α signaling in the genesis of cancer treatment related symptoms (CTRS): a study using cytokine receptor-deficient mice.

Cytotoxic chemotherapeutic agents often induce a cluster of cancer treatment related symptoms (CTRS). The purpose of this study was to develop a mouse model of CTRS to examine the role of IL-1ß and TNF-α signaling in the genesis of these symptoms. CTRS (change in wheel running activity, food intake, and body weight from baseline) were examined in wild type (WT) mice or mice lacking the TNF-α p55 (type 1) receptor (TNFR1-/-) and/or IL-1ß type 1 receptor (IL-1R1-/-) injected with four doses of cyclophosphamide/Adriamycin/5-fluorouracil (CAF) at 20-day intervals. Inflammatory cytokines in blood and tissues were measured using multiplex immunoassays and quantitative RT-PCR. ANOVA was used to examine differences between genotype and/or treatment group. Kaplan-Meier analysis was used to estimate survival rate. CAF rapidly increased IL-1ß and TNF-α signaling in WT mice. CAF induced acute CTRS immediately following drug injection which returned to baseline prior to the next CAF dose. Persistent CTRS were evident 3weeks after the 4th CAF dose. Acute but not persistent CTRS were associated with increased levels of IL-7, IL-9, KC, MCP-1, GCSF, and IP-10. This CAF induced inflammatory response was blunted in IL-1R1 deficient mice and absent in IL-1R1/TNFR1-deficient mice. IL-1R1-/- mice showed an identical pattern of CTRS to their WT counterparts. The assessment of CTRS in IL-1R1/TNF-R1-deficient mice was precluded by severe toxicity. Our data suggest that an important function of the IL-1ß and TNF-α driven inflammatory cascade is to promote recovery following exposure to cytotoxic agents.

Small molecule kinase inhibitors block the ZAK-dependent inflammatory effects of doxorubicin.

The adverse side effects of doxorubicin, including cardiotoxicity and cancer treatment-related fatigue, have been associated with inflammatory cytokines, many of which are regulated by mitogen-activated protein kinases (MAPKs). ZAK is an upstream kinase of the MAPK cascade. Using mouse primary macrophages cultured from ZAK-deficient mice, we demonstrated that ZAK is required for the activation of JNK and p38 MAPK by doxorubicin. Nilotinib, ponatinib and sorafenib strongly suppressed doxorubicin-mediated phosphorylation of JNK and p38 MAPK. In addition, these small molecule kinase inhibitors blocked the expression of IL-1ß, IL-6 and CXCL1 RNA and the production of these proteins. Co-administration of nilotinib and doxorubicin to mice decreased the expression of IL-1ß RNA in the liver and suppressed the level of IL-6 protein in the serum compared with mice that were injected with doxorubicin alone. Therefore, by reducing the production of inflammatory mediators, the inhibitors identified in the current study may be useful in minimizing the side effects of doxorubicin and potentially other chemotherapeutic drugs.

Fibroblast growth factor receptor 3 effects on proliferation and telomerase activity in sheep growth plate chondrocytes.

BACKGROUND: Fibroblast growth factor receptor 3 (FGFR3) inhibits growth-plate chondrocyte proliferation and limits bone elongation. Gain-of-function FGFR3 mutations cause dwarfism, reduced telomerase activity and shorter telomeres in growth plate chondroyctes suggesting that FGFR3 reduces proliferative capacity, inhibits telomerase, and enhances senescence. Thyroid hormone (T3) plays a role in cellular maturation of growth plate chondrocytes and a known target of T3 is FGFR3. The present study addressed whether reduced FGFR3 expression enhanced telomerase activity, mRNA expression of telomerase reverse transcriptase (TERT) and RNA component of telomerase (TR), and chondrocyte proliferation, and whether the stimulation of FGFR3 by T3 evoked the opposite response. RESULTS: Sheep growth-plate proliferative zone chondrocytes were cultured and transfected with siRNA to reduce FGFR3 expression; FGFR3 siRNA reduced chondrocyte FGFR3 mRNA and protein resulting in greater proliferation and increased TERT mRNA expression and telomerase activity (p < 0.05). Chondrocytes treated with T3 significantly enhanced FGFR3 mRNA and protein expression and reduced telomerase activity (p < 0.05); TERT and TR were not significantly reduced. The action of T3 at the growth plate may be partially mediated through the FGFR3 pathway. CONCLUSIONS: The results suggest that FGFR3 inhibits chondrocyte proliferation by down-regulating TERT expression and reducing telomerase activity indicating an important role for telomerase in sustaining chondrocyte proliferative capacity during bone elongation.

Canine fibroblast growth factor receptor 3 sequence is conserved across dogs of divergent skeletal size.

BACKGROUND: Fibroblast growth factor receptor 3 (FGFR3) is expressed in the growth plate of endochondral bones and serves as a negative regulator of linear bone elongation. Activating mutations severely limit bone growth, resulting in dwarfism, while inactivating mutations significantly enhance bone elongation and overall skeletal size. Domesticated dogs exhibit the greatest skeletal size diversity of any species and, given the regulatory role of FGFR3 on growth plate proliferation, we asked whether sequence differences in FGFR3 could account for some of the size differences. METHODS: All exons, the promoter region, and 60 bp of the 3' flanking region of the canine FGFR3 gene were sequenced for nine different dog breeds representing a spectrum of skeletal size. The resultant sequences were compared to the reference Boxer genome sequence. RESULTS: There was no variation in sequence for any FGFR3 exons, promoter region, or 3' flanking sequence across all breeds evaluated. CONCLUSION: The results suggest that, regardless of domestication selection pressure to develop breeds having extreme differences in skeletal size, the FGFR3 gene is conserved. This implies a critical role for this gene in normal skeletal integrity and indicates that other genes account for size variability in dogs.