A SUMOylation-defective MITF germline mutation predisposes to melanoma and renal carcinoma.

So far, no common environmental and/or phenotypic factor has been associated with melanoma and renal cell carcinoma (RCC). The known risk factors for melanoma include sun exposure, pigmentation and nevus phenotypes; risk factors associated with RCC include smoking, obesity and hypertension. A recent study of coexisting melanoma and RCC in the same patients supports a genetic predisposition underlying the association between these two cancers. The microphthalmia-associated transcription factor (MITF) has been proposed to act as a melanoma oncogene; it also stimulates the transcription of hypoxia inducible factor (HIF1A), the pathway of which is targeted by kidney cancer susceptibility genes. We therefore proposed that MITF might have a role in conferring a genetic predisposition to co-occurring melanoma and RCC. Here we identify a germline missense substitution in MITF (Mi-E318K) that occurred at a significantly higher frequency in genetically enriched patients affected with melanoma, RCC or both cancers, when compared with controls. Overall, Mi-E318K carriers had a higher than fivefold increased risk of developing melanoma, RCC or both cancers. Codon 318 is located in a small-ubiquitin-like modifier (SUMO) consensus site (ΨKXE) and Mi-E318K severely impaired SUMOylation of MITF. Mi-E318K enhanced MITF protein binding to the HIF1A promoter and increased its transcriptional activity compared to wild-type MITF. Further, we observed a global increase in Mi-E318K-occupied loci. In an RCC cell line, gene expression profiling identified a Mi-E318K signature related to cell growth, proliferation and inflammation. Lastly, the mutant protein enhanced melanocytic and renal cell clonogenicity, migration and invasion, consistent with a gain-of-function role in tumorigenesis. Our data provide insights into the link between SUMOylation, transcription and cancer.

Metformin: An anti-diabetic drug to fight cancer.

Since epidemiologic data have highlighted the positive effects of metformin to reduce cancer incidence and mortality, many in vitro and in vivo studies as well as a large number of clinical trials have been conducted in order to study its potential. The many anticancer actions of metformin lead to a cytostatic effect. Two distinct but not exclusive mechanisms can be implicated in these actions. First, by decreasing insulinemia and glycaemia, metformin can block the PI3K/MAPK signalling pathway implicated in cell growth. Second, metformin can directly act on cancer cells by targeting various pathways including tumour metabolism, inflammation, angiogenesis or cancer stem cells, mainly through the activation of the AMPK pathway. Nonetheless, although metformin alone displays chemopreventive properties, it does not seem to be sufficient to treat cancer, raising the need to be combined with other drugs (e.g. chemotherapy or glycolysis inhibitors) in order to synergistically reveal its cytotoxic action. However, in particular conditions such as specific mutations (e.g. LKB, p53 or OCT1) or low glucose availability, metformin alone does have cytotoxic effects. Thus, it is essential to consider the associated biomarkers in order to determine the potential of metformin in different types of cancers.

Determination of ketamine and its main metabolites by liquid chromatography coupled to tandem mass spectrometry in pig plasma: Comparison of extraction methods.

A rapid, sensitive and specific liquid chromatography coupled to tandem mass spectrometry method was developed for the simultaneous quantification pig plasma of ketamine and its two principal metabolites, norketamine and dehydronorketamine. Three extraction procoles were assessed including acetonitrile precipitation, Oase™ microplate extraction, and liquid-liquid extraction. Oase™ microplate extraction induced no significant matrix effect, important signal/noise ratio and good recoveries, ranging from 82 to 87% for the considered compounds. Using this extraction procedure, the assay was linear in the dynamic range 10-3000ng/mL (R2>0.99) regardless of the analytes. Intra- and inter-day accuracies were less than 12% for all compounds and intra- and inter-day precisions expressed as RSD were within <9.9%. Samples were stable in different storage conditions. High ketamine, norketamine and dehydronorketamine concentrations up to 15,000ng/mL can be determined with good precision using appropriate sample dilution. The assay was successfully applied to pig plasma samples to determine the pharmacokinetics of ketamine and the consecutive metabolites after buccal administration of a 4mg/kg ketamine base solutions.