Germline mutations in the FH gene encoding the Krebs cycle enzyme fumarate hydratase predispose to hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome. FH-deficient cells and tissues accumulate high levels of fumarate, which may act as an oncometabolite and contribute to tumourigenesis. A recently proposed role for fumarate in the covalent modification of cysteine residues to S-(2-succinyl) cysteine (2SC) (termed protein succination) prompted us to assess 2SC levels in our existing models of HLRCC. Herein, using a previously characterized antibody against 2SC, we show that genetic ablation of FH causes high levels of protein succination. We next hypothesized that immunohistochemistry for 2SC would serve as a metabolic biomarker for the in situ detection of FH-deficient tissues. Robust detection of 2SC was observed in Fh1 (murine FH)-deficient renal cysts and in a retrospective series of HLRCC tumours (n = 16) with established FH mutations. Importantly, 2SC was undetectable in normal tissues (n = 200) and tumour types not associated with HLRCC (n = 1342). In a prospective evaluation of cases referred for genetic testing for HLRCC, the presence of 2SC-modified proteins (2SCP) correctly predicted genetic alterations in FH in every case. In two series of unselected type II papillary renal cancer (PRCC), prospectively analysed by 2SCP staining followed by genetic analysis, the biomarker accurately identified previously unsuspected FH mutations (2/33 and 1/36). The investigation of whether metabolites in other tumour types produce protein modification signature(s) that can be assayed using similar strategies will be of interest in future studies of cancer.

Human 2-oxoglutarate oxygenases catalyse a range of biological oxidations including the demethylation of histone and nucleic acid substrates and the hydroxylation of proteins and small molecules. Some of these processes are centrally involved in regulation of cellular responses to hypoxia. The ALKBH proteins are a sub-family of 2OG oxygenases that are defined by homology to the Escherichia coli DNA-methylation repair enzyme AlkB. Here we report evidence that ALKBH5 is probably unique amongst the ALKBH genes in being a direct transcriptional target of hypoxia inducible factor-1 (HIF-1) and is induced by hypoxia in a range of cell types. We show that purified recombinant ALKBH5 is a bona fide 2OG oxygenase that catalyses the decarboxylation of 2OG but appears to have different prime substrate requirements from those so far defined for other ALKBH family members. Our findings define a new class of HIF-transcriptional target gene and suggest that ALKBH5 may have a role in the regulation of cellular responses to hypoxia.

Hepatic progenitor cells (HPC) appear in a variety of liver diseases. Their occurrence in chronic hepatitis C (CHC) remains unclear, and triggering factors have to be elucidated. The presence of HPC in CHC was examined in relation to histological and virological parameters and patient age. Fifty liver biopsies of HCV-infected patients were examined. The presence of HPC was evaluated by immunohistochemical expression of keratin 7 (K7). Double immunostaining with K7 and cell proliferation marker Ki-67 was undertaken. Ductular reaction at the limiting plate, mean number of isolated progenitor cells (IPC) and isolated ductular structures (IDS) were quantified. The predominant distribution pattern of IPC and IDS and the presence of K7(+) hepatocytes were registered. Relationship between ductular reaction, IPC, IDS, presence of K7(+) hepatocytes, and patient age, hepatitis grade and stage, HCV RNA, and HCV genotype was examined. Prominent ductular reaction and increased numbers of IPC and IDS correlated significantly with older age and severe fibrosis/cirrhosis. The above HPC subtypes were not proliferating. Periportal/periseptal distribution pattern of IPC and IDS and presence of K7(+) hepatocytes were significantly more frequent in advanced hepatitis stages and in patients older than 40 years. Intraparenchymal distribution pattern correlated with younger age, lobular activity, and early fibrosis stage. K7(+) hepatocytes were encountered almost exclusively in the periportal pattern and in the presence of interface hepatitis and were more frequent among HCV genotype-1 patients. HPC activation in CHC is a common but diverse phenomenon closely related to patient age and hepatitis stage.

Lymphomas associated with Warthin's tumor (WT) are extremely uncommon and the majorities are of B cell type. We report the simultaneous occurrence of T-cell lymphoblastic lymphoma (T-LBL) and WT in an 81-year-old patient, who presented with fever, night sweats and enlargement of the right parotid gland. The parotidectomy specimen showed a WT with extensive replacement of the lymphoid stroma by T-LBL, but preservation of the oncocytic epithelium. Staging investigations revealed mediastinal and abdominal lymphadenopathy, bilateral pleural effusions and bone marrow infiltration, in keeping with stage IVB disease. The patient received combination chemotherapy treatment but responded poorly, and died three months after diagnosis. To our knowledge, this is the first case report of T-LBL involving WT. The present study indicates that the lymphoid stroma in WT belongs to the systemic lymphoid tissue and can be involved in disseminated lymphoma. It highlights the importance of careful examination of WT's lymphoid stroma for the possible presence of any coexistent malignancy.

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