An epigenetic candidate-gene association study of parental styles in suicide attempters with substance use disorders

Suicide attempts (SA) are prevalent in substance use disorders (SUD). Epigenetic mechanisms may play a pivotal role in the molecular mechanisms of environmental effects eliciting suicidal behaviour in this population. Hypothalamic-pituitary-adrenal axis (HPA), oxytocin and neurotrophin pathways have been consistently involved in SA, yet , their interplay with childhood adversity remains unclear, particularly in SUD. In 24 outpatients with SUDs, we examined the relation between three parental dysfunctional styles and history of SA with methylation of 32 genes from these pathways, eventually analysing 823 methylation sites. Extensive phenotypic characterization was obtained using a semi-structured interview. Parental style was patient-reported using the Measure of Parental Style (MOPS) questionnaire, analysed with and without imputation of missing items. Linear regressions were performed to adjust for possible confounders, followed by multiple testing correction. We describe both differentially methylated probes (DMPs) and regions (DMRs) for each set of analyses (with and without imputation of MOPS items). Without imputation, five DMRs in OXTR, CRH and NTF3 significantly interacted with MOPS father abuse to increase the risk for lifetime SA, thus covering the three pathways. After imputation of missing MOPS items, two other DMPs from FKBP5 and SOCS3 significantly interacted with each of the three father styles to increase the risk for SA. Although our findings must be interpreted with caution due to small sample size, they suggest implications of stress reactivity genes in the suicidal risk of SUD patients and highlight the significance of father dysfunction as a potential marker of childhood adversity in SUD patients.

Synergistic activity of everolimus and 5-aza-2'-deoxycytidine in medullary thyroid carcinoma cell lines

Medullary thyroid cancer (MTC) is a tumor highly resistant to chemo‐ and radiotherapy. Drug resistance can be induced by epigenetic changes such as aberrant DNA methylation. To overcome drug resistance, we explored a promising approach based on the use of 5‐aza‐2′‐deoxycytidine (AZA), a demethylating agent, in combination with the mTOR inhibitor everolimus in MTC cells (MZ‐CRC‐1 and TT). This combined treatment showed a strong synergistic antiproliferative activity through the induction of apoptosis. The effect of everolimus and/or AZA on genome‐wide expression profiling was evaluated by Illumina BeadChip in MZ‐CRC‐1 cells. An innovative bioinformatic pipeline identified four potential molecular pathways implicated in the synergy between AZA and everolimus: PI3K‐Akt signaling, the neurotrophin pathway, ECM/receptor interaction, and focal adhesion. Among these, the neurotrophin signaling pathway was most directly involved in apoptosis, through the overexpression of NGFR and Bax genes. The increased expression of genes involved in the NGFR‐MAPK10‐TP53‐Bax/Bcl2 pathway during incubation with AZA plus everolimus was validated by western blotting in MZ‐CRC‐1 cells. Interestingly, addition of a neutralizing anti‐NGFR antibody inhibited the synergistic cytotoxic activity between AZA and everolimus. These results open a new therapeutic scenario for MTC and potentially other neuroendocrine tumors, where therapy with mTOR inhibitors is currently approved.