FGF signaling inhibits the proliferation of human myeloma cells and reduces c-myc expression

The role of fibroblast growth factors in tumor growth

Biological processes that drive cell growth are exciting targets for cancer therapy. The fibroblast growth factor (FGF) signaling network plays a ubiquitous role in normal cell growth, survival, differentiation, and angiogenesis, but has also been implicated in tumor development. Elucidation of the roles and relationships within the diverse FGF family and of their links to tumor growth and progression will be critical in designing new drug therapies to target FGF receptor (FGFR) pathways. Recent studies have shown that FGF can act synergistically with vascular endothelial growth factor (VEGF) to amplify tumor angiogenesis, highlighting that targeting of both the FGF and VEGF pathways may be more efficient in suppressing tumor growth and angiogenesis than targeting either factor alone. In addition, through inducing tumor cell survival, FGF has the potential to overcome chemotherapy resistance highlighting that chemotherapy may be more effective when used in combination with FGF inhibitor therapy. Furthermore, FGFRs have variable activity in promoting angiogenesis, with the FGFR-1 subgroup being associated with tumor progression and the FGFR-2 subgroup being associated with either early tumor development or decreased tumor progression. This review highlights the growing knowledge of FGFs in tumor cell growth and survival, including an overview of FGF intracellular signaling pathways, the role of FGFs in angiogenesis, patterns of FGF and FGFR expression in various tumor types, and the role of FGFs in tumor progression.

Coordination of upregulated XBP-1 and downregulated c-myc during myeloma cell differentiation induced by 2-methoxyestradiol

Our previous studies showed that 2-methoxyestradiol (2ME2) at low concentrations (0.1-0.5 micromol/l) could induce differentiation of myeloma cells, and transcription factors Blimp-1 and XBP-1 repressed by Pax-5 were both upregulated. The present study was aimed at elucidating the molecular mechanism underlying 2ME2-induced myeloma cell differentiation. We demonstrated that cell differentiation required not only Blimp-1 to upregulate XBP-1expression but also Blimp-1 to inhibit c-myc activity. These two signal transduction pathways worked dependently of each other and synergistically to promote the differentiation process of myeloma cells.

The human GIMAP5 gene has a common polyadenylation polymorphism increasing risk to systemic lupus erythematosus

BACKGROUND

Several members of the GIMAP gene family have been suggested as being involved in different aspects of the immune system in different species. Recently, a mutation in the GIMAP5 gene was shown to cause lymphopenia in a rat model of autoimmune insulin-dependent diabetes. Thus it was hypothesised that genetic variation in GIMAP5 may be involved in susceptibility to other autoimmune disorders where lymphopenia is a key feature, such as systemic lupus erythematosus (SLE).

MATERIAL AND METHODS

To investigate this, seven single nucleotide polymorphisms in GIMAP5 were analysed in five independent sets of family-based SLE collections, containing more than 2000 samples.

RESULT

A significant increase in SLE risk associated with the most common GIMAP5 haplotype was found (OR 1.26, 95% CI 1.02 to 1.54, p = 0.0033). In families with probands diagnosed with trombocytopenia, the risk was increased (OR 2.11, 95% CI 1.09 to 4.09, p = 0.0153). The risk haplotype bears a polymorphic polyadenylation signal which alters the 3' part of GIMAP5 mRNA by producing an inefficient polyadenylation signal. This results in higher proportion of non-terminated mRNA for homozygous individuals (p<0.005), a mechanism shown to be causal in thalassaemias. To further assess the functional effect of the polymorphic polyadenylation signal in the risk haplotype, monocytes were treated with several cytokines affecting apoptosis. All the apoptotic cytokines induced GIMAP5 expression in two monocyte cell lines (1.5-6 times, p<0.0001 for all tests).

CONCLUSION

Taken together, the data suggest the role of GIMAP5 in the pathogenesis of SLE.