Diabetic patients treated with metformin have a reduced incidence of cancer and cancerrelated mortality. Here we show that metformin affects engraftment and growth of breast cancer tumours in mice. This correlates with the induction of metabolic changes compatible with clear anticancer effects. We demonstrate that microRnA modulation underlies the anticancer metabolic actions of metformin. In fact, metformin induces DICER expression and its effects are severely impaired in DICER knocked down cells. Conversely, ectopic expression of DICER recapitulates the effects of metformin in vivo and in vitro. The microRnAs upregulated by metformin belong mainly to energy metabolism pathways. Among the messenger RnAs downregulated by metformin, we found c-mYC, IRs-2 and HIF1alpha. Downregulation of c-mYC requires AmP-activated protein kinase-signalling and mir33a upregulation by metformin. Ectopic expression of c-mYC attenuates the anticancer metabolic effects of metformin. We suggest that DICER modulation, mir33a upregulation and c-mYC targeting have an important role in the anticancer metabolic effects of metformin.

BackgroundCystic fibrosis (CF) is a disorder affecting the respiratory, digestive, reproductive systems and sweat glands. This lethal hereditary disease has known or suspected links to the dysbiosis gut microbiota. High-throughput meta-omics-based approaches may assist in unveiling this complex network of symbiosis modifications.ObjectivesThe aim of this study was to provide a predictive and functional model of the gut microbiota enterophenotype of pediatric patients affected by CF under clinical stability.MethodsThirty-one fecal samples were collected from CF patients and healthy children (HC) (age range, 1–6 years) and analysed using targeted-metagenomics and metabolomics to characterize the ecology and metabolism of CF-linked gut microbiota. The multidimensional data were low fused and processed by chemometric classification analysis.ResultsThe fused metagenomics and metabolomics based gut microbiota profile was characterized by a high abundance of Propionibacterium, Staphylococcus and Clostridiaceae, including Clostridium difficile, and a low abundance of Eggerthella, Eubacterium, Ruminococcus, Dorea, Faecalibacterium prausnitzii, and Lachnospiraceae, associated with overexpression of 4-aminobutyrate (GABA), choline, ethanol, propylbutyrate, and pyridine and low levels of sarcosine, 4-methylphenol, uracil, glucose, acetate, phenol, benzaldehyde, and methylacetate. The CF gut microbiota pattern revealed an enterophenotype intrinsically linked to disease, regardless of age, and with dysbiosis uninduced by reduced pancreatic function and only partially related to oral antibiotic administration or lung colonization/infection.ConclusionsAll together, the results obtained suggest that the gut microbiota enterophenotypes of CF, together with endogenous and bacterial CF biomarkers, are direct expression of functional alterations at the intestinal level. Hence, it’s possible to infer that CFTR impairment causes the gut ecosystem imbalance.This new understanding of CF host-gut microbiota interactions may be helpful to rationalize novel clinical interventions to improve the affected children’s nutritional status and intestinal function.

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