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.

Inflammation response of epithelial mucosa to chemo- radiotherapy cytotoxic effects leads to mucositis, a painful side effect of antineoplastic treatments. About 40% of the patients treated with chemotherapy develop mucositis; this percentage rises to about 90% for head and neck cancer patients (HNC) treated with both chemo- and radiotherapy. 19% of the latter will be hospitalized and will experience a delay in antineoplastic treatment for high-grade mucositis management, resulting in a reduction of the quality of life, a worse prognosis and an increase in patient management costs. Currently, several interventions and prevention guidelines are available, but their effectiveness is uncertain. This review comprehensively describes mucositis, debating the impact of standard chemo-radiotherapy and targeted therapy on mucositis development and pointing out the limits and the benefits of current mucositis treatment strategies and assessment guidelines. Moreover, the review critically examines the feasibility of the existing biomarkers to predict patient risk of developing oral mucositis and their role in early diagnosis. Despite the expression levels of some proteins involved in the inflammation response, such as TNF-α or IL-1β, partially correlate with mucositis process, their presence does not exclude others mucositis-independent inflammation events. This strongly suggests the need to discover biomarkers that specifically feature mucositis process development. Non-coding RNAs might hold this potential.

Background Head and neck squamous cell carcinoma (HNSCC) is the sixth leading cancer worldwide. They are typically characterized by a high incidence of local recurrence, which is the most common cause of death in HNSCC patients. TP53 is the most frequently mutated gene in HNSCC and patients carrying TP53 mutations are associated with a higher probability to develop local recurrence. MiRNAs, which are among the mediators of the oncogenic activity of mt-p53 protein, emerge as an appealing tool for screening, diagnosis and prognosis of cancer. We previously identified a signature of 12 miRNAs whose aberrant expression associated with TP53 mutations and was prognostic for HNSCC. Among them miR-96-5p emerges as an oncogenic miRNAs with prognostic significance in HNSCC. Methods To evaluate the oncogenic role of miR-96-5p in a tumoral context, we performed colony formation, cell migration and cell viability assays in two HNSCC cell lines transfected for miR-96-5p mimic or inhibitor and treated with or without radio/chemo-therapy. In addition, to identify genes positively and negatively correlated to miR-96-5p expression in HNSCC, we analyzed the correlation between gene expression and miR-96-5p level in the subset of TCGA HNSCC tumors carrying missense TP53 mutations by Spearman and Pearson correlation. To finally identify targets of miR-96-5p, we used in silico analysis and the luciferase reporter assay to confirm PTEN as direct target. Results Our data showed that overexpression of miR-96-5p led to increased cell migration and radio-resistance, chemotherapy resistance in HNSCC cells. In agreement with these results, among the most statistically significant pathways in which miR-96-5p is involved, are focal Adhesion, extracellular matrix organization and PI3K-Akt-mTOR-signaling pathway. As a direct target of miR-96-5p, we identified PTEN, the main negative regulator of PI3K-Akt signalling pathway activation. Conclusions These results highlight a new mechanism of chemo/radio-resistance insurgence in HNSCC cells and support the possibility that miR-96-5p expression could be used as a novel promising biomarker to predict radiotherapy response and local recurrence development in HNSCC patients. In addition, the identification of pathways in which miR-96-5p is involved could contribute to develop new therapeutic strategies to overcome radio-resistance. Electronic supplementary material The online version of this article (10.1186/s13046-019-1119-x) contains supplementary material, which is available to authorized users.

Over 70% of head & neck squamous cell carcinoma (HNSCC) patients carry TP53 oncogenic mutations. Here we studied the role of specific tumor-derived mutant p53 proteins in the aberrant transcription of long non-coding (lnc) MIR205HG gene in head and neck cancer cells.Methods: To understand the role of lncMIR205HG, that we showed to be transcriptionally regulated by mutant p53 in HNSCC, we have employed siRNA and shRNA in CAL27 and FaDu HNSCC cell lines to suppress p53 gene expression in ChIP assays and RT-qPCR. We validated our findings in a cohort of 522 HNSCC patients from The Cancer Genome Atlas Data Portal (TCGA). We further evaluated our results in 63 HNSCC tumor samples collected at our institute, 32 of which were characterized by mutated TP53 (missense mutations) while 31 were characterized by wild-type TP53.Results: Maturation of pre-MIR205HG transcript produces two non-coding RNAs, lncMIR205HG and hsa-miR-205-5p. Down-regulation of lncMIR205HG expression significantly reduced cell proliferation, cell migration and clonogenic activity of head and neck cancer cells. Expression of MIR205HG was significantly increased in HNSCC with mutated TP53 when compared with matched non-tumoral tissues. Furthermore, MIR205HG expression levels were significantly higher in tumoral samples with mutant p53 than in tumoral tissues expressing wild-type p53. Mechanistically, MIR205HG depletes endogenous miR-590-3p leading to increased cyclin B, cdk1, and YAP protein expression.Conclusions: Taken together, these findings identify a transcriptional and post-transcriptional molecular network that includes mutant p53 protein, lncMIR205HG, YAP, and other proliferation-related genes, which are enriched in HNSCC patients with poor prognosis.

Metformin is a commonly prescribed type II diabetes medication that exhibits promising anticancer effects. Recently, these effects were found to be associated, at least in part, with a modulation of microRNA expression. However, the mechanisms by which single modulated microRNAs mediate the anticancer effects of metformin are not entirely clear and knowledge of such a process could be vital to maximize the potential therapeutic benefits of this safe and well-tolerated therapy. Our analysis here revealed that the expression of miR-21-5p was downregulated in multiple breast cancer cell lines treated with pharmacologically relevant doses of metformin. Interestingly, the inhibition of miR-21-5p following metformin treatment was also observed in mouse breast cancer xenografts and in sera from 96 breast cancer patients. This modulation occurred at the levels of both pri-miR-21 and pre-miR-21, suggesting transcriptional modulation. Antagomir-mediated ablation of miR-21-5p phenocopied the effects of metformin on both the clonogenicity and migration of the treated cells, while ectopic expression of miR-21-5p had the opposite effect. Mechanistically, this reduction in miR-21-5p enhanced the expression of critical upstream activators of the AMP-activated protein kinase, calcium-binding protein 39-like and Sestrin-1, leading to AMP-activated protein kinase activation and inhibition of mammalian target of rapamycin signaling. Importantly, these effects of metformin were synergistic with those of everolimus, a clinically relevant mammalian target of rapamycin inhibitor, and were independent of the phosphatase and tensin homolog status. This highlights the potential relevance of metformin in combinatorial settings for the treatment of breast cancer.

TRANSLATIONAL RELEVANCEHead and neck squamous cell carcinoma (HNSCC) is typically characterized by mutation of TP53 gene, associated to therapy resistance and high incidence of local recurrences. However, drugs specifically targeting mutant p53 proteins, frequently presenting gain-of-function activity associated with radioresistance, are not available. We then set out to identify mutant p53-associated functions that might be targeted with drugs currently used in HNSCC trials. This study identifies MYC as a crucial mediator of mutant p53 activity in HNSCC and PI3K inhibitors as compounds able to impinge on mutant p53-MYC dependent gene expression. Of note, down-regulation of mutant p53-MYC dependent genes is associated with response to PI3Kα-selective inhibitor Alpesilib (BYL719) in HNSCC.Research.

Malignant pleural mesothelioma is a poorly treated neoplasia arising from the pleural mesothelial lining. Here we document that the leaf extract of Cynara scolymus exerts broad antitumoral effects both in vitro and in vivo on mesothelioma cell lines. We found that Cynara scolymus treatment affects strongly cell growth, migration and tumor engraftment of mesothelioma cell lines. Strikingly, dietary feeding with Cynara scolymus leaf extract reduces the growth of mesothelioma xenografted tumors similarly to pemetrexed, a commonly employed drug in the treatment of mesothelioma. In aggregate our findings suggest that leaf extract of Cynara scolymus holds therapeutic potential for the treatment of mesothelioma.

We have previously shown that melatonin exerts tumor suppressor activities by inducing the p38-p53 axis. This occurred within a few hours while no data are available on how melatonin pathway can be sustained on the long term. Here we show that miR-24, which has been demonstrated to target genes involved in the DNA repair process, targets p38, p53, PML and H2AX simultaneously. We show that long-term treatment with melatonin can decrease miR-24 levels post-transcriptionally, which pairs with a long-wave regulation of genes involved in cell proliferation, DNA damage, RNA metabolism and cell shape and transformation. Moreover, we show that melatonin can inhibit cell proliferation and migration, at least in part, by downregulating miR-24. Furthermore, we propose the involvement of hnRNP A1, which is downregulated by melatonin and involved in miRNA processing, in the regulation of miR-24 levels by melatonin. We conclude showing that miR-24 is upregulated in colon, breast and head and neck datasets and its levels negatively correlate with overall survival.