GAPDH enhances the aggressiveness and the vascularization of non-Hodgkin's B lymphomas via NF-κB-dependent induction of HIF-1α

Deregulated expression of glycolytic enzymes contributes not only to the increased energy demands of transformed cells but also has non-glycolytic roles in tumors. However, the contribution of these non-glycolytic functions in tumor progression remains poorly defined. Here, we show that elevated expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), but not of other glycolytic enzymes tested, increased aggressiveness and vascularization of non-Hodgkin's lymphoma. Elevated GAPDH expression was found to promote nuclear factor-κB (NF-κB) activation via binding to tumor necrosis factor receptor-associated factor-2 (TRAF2), enhancing the transcription and the activity of hypoxia-inducing factor-1α (HIF-1α). Consistent with this, inactive mutants of GAPDH failed to bind TRAF2, enhance HIF-1 activity or promote lymphomagenesis. Furthermore, elevated expression of gapdh mRNA in biopsies from diffuse large B-cell non-Hodgkin's lymphoma patients correlated with high levels of hif-1α, vegf-a, nfkbia mRNA and CD31 staining. Collectively, these data indicate that deregulated GAPDH expression promotes NF-κB-dependent induction of HIF-1α and has a key role in lymphoma vascularization and aggressiveness.

In vitro endothelial cell susceptibility to xenobiotics: Comparison of three cell types

In three different endothelial cell (EC) cultures (primary human umbilical cord vein, so-called HUVEC; and immortalized cell lines HBMEC and EA-hy-926), the effects of different xenobiotics were studied in order to standardize vascular EC models for in vitro pharmacotoxicological studies. Cell characteristics were first investigated by the production and the mRNA levels of known endothelial markers in the three EC culture models. EC secretory products, tissue plasminogen activator (tPA) and von Willebrand factor (vWF), were present in the supernatant of the immortalized cell lines. The mRNA levels of vWF, tPA, platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), and beta -integrin subunit, which are involved in the control of platelet function, coagulation, and fibrinolysis as well as in cell-matrix interactions, were investigated in all EC types. For at least three parameters, cultured cells provided marked characteristics of EC phenotype, in HUVEC and in immortalized cell lines, regardless of their origin from the macro- or microcirculation. Toxicity experiments were assessed after 24 h exposure to cadmium, cyclosporin A and cisplatin by MTT assay. These experiments show nonsignificant difference in susceptibility to cyclosporin A and cadmium on HUVEC, HBMEC, and EA-hy-926. However, HBMEC, seems to be highly susceptible to cisplatin compared to HUVEC, the latter being more sensitive than EA-hy-926. For experiments conducted with cyclosporin and cadmium, cell lines could constitute an alternative material for routine cytotoxicity studies.