Isocitrate dehydrogenases (IDH) convert isocitrate to alpha-ketoglutarate (α-KG). In cancer, mutant IDH1/2 reduces α-KG to D2-hydroxyglutarate (D2-HG) disrupting α-KG-dependent dioxygenases. However, the physiological relevance of controlling the interconversion of D2-HG into α-KG, mediated by D2-hydroxyglutarate dehydrogenase (D2HGDH), remains obscure. Here we show that wild-type D2HGDH elevates α-KG levels, influencing histone and DNA methylation, and HIF1α hydroxylation. Conversely, the D2HGDH mutants that we find in diffuse large B-cell lymphoma are enzymatically inert. D2-HG is a low-abundance metabolite, but we show that it can meaningfully elevate α-KG levels by positively modulating mitochondrial IDH activity and inducing IDH2 expression. Accordingly, genetic depletion of IDH2 abrogates D2HGDH effects, whereas ectopic IDH2 rescues D2HGDH-deficient cells. Our data link D2HGDH to cancer and describe an additional function for the enzyme: the regulation of IDH2 activity and α-KG-mediated epigenetic remodeling. These data further expose the intricacies of mitochondrial metabolism and inform on the pathogenesis of D2HGDH-deficient diseases.

We report that all- trans retinoic acid (ATRA) enhanced the toxicity of docetaxel against DU145 and LNCaP prostate cancer cells, and that the nature of the interaction between ATRA and docetaxel was highly synergistic. Docetaxel-induced apoptotic cell death was associated with phosphorylation and hence inactivation of Bcl-2. ATRA enhanced docetaxel-induced apoptosis and combined treatment with ATRA and docetaxel resulted in down-regulation of Bcl-2. Docetaxel caused phosphorylation and hence inactivation of cdc2 kinase result ing in G2/M arrest. ATRA inhibited docetaxel-induced phosphorylation of cdc2 resulting in activation of cdc2 kinase and partial reversal of the G2/M arrest. ATRA also inhibited docetaxel-induced activation of MAPK indicating that the effects of docetaxel and ATRA on cdc2 phosphorylation are dependent on MAPK. We conclude that ATRA synergistically enhances docetaxel toxicity by down-regulating Bcl-2 expression and partially reverses the docetaxel-induced G2/M arrest by inhibiting docetaxel-induced cdc2 phosphorylation in a pathway that is dependent on MAPK. © 2001 Cancer Research Campaign http://www.bjcancer.com

Background. Patients with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) demonstrate aberrant activation of the phosphotidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. We examined the efficacy of everolimus, an mTOR inhibitor, in patients with recurrent or metastatic HNSCC. Methods. This single-arm phase II study enrolled biomarker-unselected patients with recurrent or metastatic HNSCC who failed at least 1 prior therapy. Everolimus was administered until progressive disease or unacceptable toxicity. Primary endpoint was clinical benefit rate (CBR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and evaluation of tissue and serum biomarkers related to the PIK3CA pathway.

Early recognition of gastrointestinal graft-versus-host disease (GI GVHD) after allogeneic hematopoietic stem cell transplantation (alloHSCT) is vital to initiation of therapy. However, the most common location, the small bowel (SB), is difficult to access with upper and lower endoscopy (UGE/LGE). Wireless capsule endoscopy (WCE) is a noninvasive technology allowing complete SB evaluation. The capsule location can also be tracked to identify motility derangements. From August 2006 to July 2007, 11 alloHSCT patients with GI symptoms underwent WCE, and visual grading was performed. UGE and LGE with biopsies were done when clinically indicated. All patients had evidence of probable acute GVHD (aGVHD) on WCE. WCE revealed lesions of greater severity than those seen by UGE or LGE in most patients. WCE demonstrated that 45% of patients had delayed gastric transit time. WCE is an excellent, noninvasive method for assessing GI GVHD, with the ability to more accurately assess the severity of GVHD, evaluate clinical symptoms, and follow response to treatment.

We conclude that the incidence and severity of transplantation-associated toxicities are similar in MM patients with and without ONJ. Long-term survival was also similar between both groups.