These results suggest that altered expression of hsa_circRNA_103636 in PBMCs is a potential novel biomarker for the diagnosis and treatment of MDD.

BackgroundThe criteria for diagnosing depression are based on behavioral observation and self-reporting of symptoms by the patients or guardians without any biological validation of the disease. This study aimed to identify long non-coding RNAs (lncRNAs) in peripheral blood mononuclear cells (PBMCs) as robust and predictive biomarkers for diagnosis and therapy response in major depressive disorder (MDD).Material/MethodsWe used human lncRNA 3.0 microarray profiling (which covers 30,586 human lncRNAs), using PBMCs from five MDD patients and five controls. Differentially expressed lncRNAs in the PBMCs of MDD patients were identified, of which 10 candidate lncRNAs were selected for real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis in a larger cohort of 138 MDD patients and 63 healthy controls. Then among the 138 MDD patients who received standard antidepressant treatment, 30 were randomly selected for lncRNAs expression retesting and symptomatology assessments after three-weeks and six-weeks of antidepressant treatment.ResultsSix lncRNAs (TCONS_00019174, ENST00000566208, NONHSAG045500, ENST00000517573, NONHSAT034045, and NONHSAT142707) were significantly downregulated in MDD patients compared to control patients, and the area under the receiver operator curve (ROC) of these six lncRNAs cases, combined, was 0.719 (95% confidence interval (CI): 0.617–0.821). There was no difference in the expression of these six lncRNAs based on gender (p>0.05) or age (p>0.05).ConclusionsThese results suggest that the combined expression of six lncRNAs in PBMCs may serve as a potential biomarker for diagnosis and therapy response of MDD in the clinical setting.

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Background WHO stated that nearly one million people commit suicide every year worldly, and 40% of the suicide completer suffered from depression. The primary aim of this study was to explore the association between long noncoding RNAs (lncRNAs) expression in peripheral blood mononuclear cells (PBMCs) and suicide risk of patients with major depressive disorder (MDD).MethodsUsing Human LncRNA 3.0 microarray profiling which includes 30,586 human lncRNAs and RT‐PCR, six down‐regulated lncRNAs were identified differentially expressed in MDD patients. According to suicidal ideation and suicidal attempt, the suicide risk of MDD patients was classified into suicidal ideation versus no suicidal ideation groups, and past attempt versus no past attempt groups, respectively. The expression of six lncRNAs in MDD patients and controls were examined by RT‐PCR.ResultsThe expression of six lncRNAs had significant differences between no suicidal ideation, suicidal ideation, and controls; corresponding lncRNAs associated with suicidal attempt had remarkable differences between no past attempt, past attempt, and controls. Additionally, only the expression of lncRNAs in suicidal ideation group and past attempt group markedly declined compared with controls.ConclusionsThis study indicated that the expression of six down‐regulated lncRNAs had a negative association with suicide risk in MDD patients, and the expression of lncRNAs in PBMCs could have the potential to help clinician judge the suicide risk of MDD patients to provide timely treatment and prevent suicide.

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