Retro-miRs: novel and functional miRNAs originating from mRNA retrotransposition.

BACKGROUND: Reverse-transcribed gene copies (retrocopies) have emerged as major sources of evolutionary novelty. MicroRNAs (miRNAs) are small and highly conserved RNA molecules that serve as key post-transcriptional regulators of gene expression. The origin and subsequent evolution of miRNAs have been addressed but not fully elucidated. RESULTS: In this study, we performed a comprehensive investigation of miRNA origination through retroduplicated mRNA sequences (retro-miRs). We identified 17 retro-miRs that emerged from the mRNA retrocopies. Four of these retro-miRs had de novo origins within retrocopied sequences, while 13 retro-miRNAs were located within exon regions and duplicated along with their host mRNAs. We found that retro-miRs were primate-specific, including five retro-miRs conserved among all primates and two human-specific retro-miRs. All retro-miRs were expressed, with predicted and experimentally validated target genes except miR-10527. Notably, the target genes of retro-miRs are involved in key biological processes such as metabolic processes, cell signaling, and regulation of neurotransmitters in the central nervous system. Additionally, we found that these retro-miRs play a potential oncogenic role in cancer by targeting key cancer genes and are overexpressed in several cancer types, including liver hepatocellular carcinoma and stomach adenocarcinoma. CONCLUSIONS: Our findings demonstrated that mRNA retrotransposition is a key mechanism for the generation of novel miRNAs (retro-miRs) in primates. These retro-miRs are expressed, conserved, have target genes with important cellular functions, and play important roles in cancer.

Association between post-operative delirium and use of volatile anesthetics in the elderly: A real-world big data approach.

STUDY OBJECTIVE: Early post-operative delirium is a common perioperative complication in the post anesthesia care unit. To date it is unknown if a specific anesthetic regime can affect the incidence of delirium after surgery. Our objective was to examine the effect of volatile anesthetics on post-operative delirium. DESIGN: Single Center Observational Study. SETTING: Post Anesthesia Care Units at a German tertiary medical center. PATIENTS: 30,075 patients receiving general anesthesia for surgery. MEASUREMENTS: Delirium was assessed with the Nursing Delirium Screening Scale at the end of the recovery period. Subgroup-specific effects of volatile anesthetics on post-operative delirium were estimated using generalized-linear-model trees with inverse probability of treatment weighting. We further assessed the age-specific effect of volatiles using logistic regression models. MAIN RESULTS: Out of 30,075 records, 956 patients (3.2%) developed delirium in the post anesthesia care unit. On average, patients who developed delirium were older than patients without delirium. We found volatile anesthetics to increase the risk (Odds exp. (B) for delirium in the elderly 1.8-fold compared to total intravenous anesthesia. Odds increases with unplanned surgery 3.0-fold. In the very old (87 years or older), the increase in delirium is 6.2-fold. This result was confirmed with internal validation and in a logistic regression model. CONCLUSIONS: Our exploratory study indicates that early postoperative delirium is associated with the use of volatile anesthetics especially in the sub-cohort of patients aged 75 years and above. Further studies should include both volatile and intravenous anesthetics to find the ideal anesthetic in elderly patients.

Effect of Intraoperative Single-Shot Application of Vancomycin in Liver Transplant Recipients on Postoperative Infections With Enterococcus faecium and Enterococcus faecalis.

OBJECTIVES: Infections are major causes of morbidity and mortality in the early postoperative period after liver transplant. We observed a high rate of enterococcal infections at our center. Therefore, we added an intraoperative single shot of vancomycin to the standard regimen of meropenem given over 5 days. The aim of this study was to determine the prevalence of both Enterococcus faecium and Enterococcus faecalis infections during the first 28 days after surgery depending on the type of antibiotic prophylaxis and their implications on mortality and morbidity. MATERIALS AND METHODS: Our retrospective cohort analysis included 179 patients: 93 patients received meropenem only and 86 patients were treated with meropenem plus vancomycin. RESULTS: During the first 28 days after transplant, microbiological tests showed that 51 patients (28.5%) were positive for Enterococcus faecium and 25 patients (14.0%) were positive for Enterococcus faecalis. Enterococcus faecium infections appeared significantly more often in patients without vancomycin (P = .013). In the second week after transplant, there was a significant reduction in Enterococcus faecium infections in the meropenem plus vancomycin group (P = .015). Enterococcus faecalis infections occurred more often in the patients receiving meropenem alone, but results were not statistically significant (P = .194). There was a trend toward more frequent renal replacement therapy in the meropenem plus vancomycin group. We found no differences between the groups regarding survival after 1 and 2 years, length of hospital stay, or duration in the intensive care unit. Overall 1-year survival was 78.8% (141/179 patients). CONCLUSIONS: Although postoperative Enterococcus species infections can be reduced after liver transplant by adding vancomycin to the intraoperative antibiotic regimen, it does not improve the long-term outcomes.

In human glioblastomas transcript elongation by alternative polyadenylation and miRNA targeting is a potent mechanism of MGMT silencing.

Favorable outcome after chemotherapy of glioblastomas cannot unequivocally be linked to promoter hypermethylation of the O6-methylguanine-DNA methyltransferase (MGMT) gene encoding a DNA repair enzyme associated with resistance to alkylating agents. This indicates that molecular mechanisms determining MGMT expression have not yet been fully elucidated. We here show that glioblastomas are capable to downregulate MGMT expression independently of promoter methylation by elongation of the 3'-UTR of the mRNA, rendering the alternatively polyadenylated transcript susceptible to miRNA-mediated suppression. While the elongated transcript is poorly expressed in normal brain, its abundance in human glioblastoma specimens is inversely correlated with MGMT mRNA expression. Using a bioinformatically guided experimental approach, we identified miR-181d, miR-767-3p, and miR-648 as significant post-transcriptional regulators of MGMT in glioblastomas; the first two miRNAs induce MGMT mRNA degradation, the latter affects MGMT protein translation. A regression model including the two miRNAs influencing MGMT mRNA expression and the MGMT methylation status reliably predicts The Cancer Genome Atlas MGMT expression data. Responsivity of MGMT expressing T98G glioma cells to temozolomide was significantly enhanced after transfection of miR-181d, miR-767-3p, and miR-648. Taken together, our results uncovered alternative polyadenylation of the MGMT 3'-UTR and miRNA targeting as new mechanisms of MGMT silencing.

Adenosine A2A receptor upregulation in human PMNs is controlled by miRNA-214, miRNA-15, and miRNA-16.

Immunosuppressive signaling via the adenosine A2A receptor (A2AR) is an important pathway to control inflammation. In immune cells, expression levels of A2ARs influence responsiveness to inflammatory stimuli. However, mechanisms driving expressional changes of A2ARs are still largely elusive. In the current study, we have investigated the impact of microRNAs (miRNAs) on A2AR expression in human polymorphonuclear leukocytes (PMNs) and T cells. Bioinformatic analyses and reporter gene assays revealed that A2AR expression is controlled by miRNA-214, miRNA-15, and miRNA-16. We detected all three miRNAs in both human PMNs and T cells. However, in PMNs, up to 10-fold higher levels of miRNA-16 and miRNA-214 were detected as compared with T cells. Upon in vitro stimulation, no significant expressional changes occurred. Expression levels of all three miRNAs strongly differed between individuals. A2AR expression also exhibited significant differences between PMNs and T cells: In PMNs, more than a 60-fold increase was seen upon LPS stimulation, whereas in T cells only a 2-fold increase was observed upon anti-CD3/CD28 activation. The extent of A2AR upregulation in PMNs strongly differed between individuals (from less than 10-fold to more than 100-fold). In PMNs, the increase in A2AR mRNA expression upon stimulation was inversely correlated with the expression levels of miRNA-214, miRNA-15, and miRNA-16 (R = -0.87, P < 0.0001); no correlation was found in human T cells. These results indicate that individual miRNA profiles gain important influence on A2AR expression regulation in PMNs upon stimulation. Determination of miRNA expression levels may help to identify patients with an increased risk for severe inflammation.

Endovascular treatment of abdominal aortic aneurysms combined with bilateral common and internal iliac aneurysms.

INTRODUCTION: Combined aneurysms of aortic and iliac arteries are rare with a prevalence of less than 0.1%. However, these combined aneurysms are associated with a high incidence of thrombosis, distal embolism, or rupture. Endovascular repair is a therapeutic option and includes embolization of the internal iliac artery in numerous cases. Embolization of the internal iliac artery may cause severe ischemia with hip and buttock complications in 2-5%. Therefore, preservation of internal iliac arteries is essential to reduce complications. PATIENT AND METHOD: We describe in detail an endovascular procedure for combined abdominal aortic (diameter of 8.6 cm) and bilateral common and internal iliac aneurysm (diameter of the left side: 6.4 cm; diameter of the right side: 4.3 cm) in a 44-year-old patient caused by media necrosis Erdheim-Gsell. The blood flow of both internal arteries was preserved in this patient. RESULT: Operation was done without any complications. Conversion to an open procedure was not necessary. During follow up (3, 6, and 12 months after operation) the patient did not develop any signs of severe hip and buttock complications. Furthermore, sonography and CT angiography revealed a good blood flow via the internal and external iliac arteries. CONCLUSION: Endovascular repair of abdominal aortic aneurysms combined with bilateral common and internal iliac aneurysms offers a promising minimal invasive procedure. Most importantly, this technique is less invasive than open operations and reduces complications by preserving the pelvic perfusion.

O-methylguanine-DNA methyltransferase (MGMT) mRNA expression predicts outcome in malignant glioma independent of MGMT promoter methylation.

BACKGROUND: We analyzed prospectively whether MGMT (O(6)-methylguanine-DNA methyltransferase) mRNA expression gains prognostic/predictive impact independent of MGMT promoter methylation in malignant glioma patients undergoing radiotherapy with concomitant and adjuvant temozolomide or temozolomide alone. As DNA-methyltransferases (DNMTs) are the enzymes responsible for setting up and maintaining DNA methylation patterns in eukaryotic cells, we analyzed further, whether MGMT promoter methylation is associated with upregulation of DNMT expression. METHODOLOGY/PRINCIPAL FINDINGS: ADULT PATIENTS WITH A HISTOLOGICALLY PROVEN MALIGNANT ASTROCYTOMA (GLIOBLASTOMA: N = 53, anaplastic astrocytoma: N = 10) were included. MGMT promoter methylation was determined by methylation-specific PCR (MSP) and sequencing analysis. Expression of MGMT and DNMTs mRNA were analysed by real-time qPCR. Prognostic factors were obtained from proportional hazards models. Correlation between MGMT mRNA expression and MGMT methylation status was validated using data from the Cancer Genome Atlas (TCGA) database (N = 229 glioblastomas). Low MGMT mRNA expression was strongly predictive for prolonged time to progression, treatment response, and length of survival in univariate and multivariate models (p<0.0001); the degree of MGMT mRNA expression was highly correlated with the MGMT promoter methylation status (p<0.0001); however, discordant findings were seen in 12 glioblastoma patients: Patients with methylated tumors with high MGMT mRNA expression (N = 6) did significantly worse than those with low transcriptional activity (p<0.01). Conversely, unmethylated tumors with low MGMT mRNA expression (N = 6) did better than their counterparts. A nearly identical frequency of concordant and discordant findings was obtained by analyzing the TCGA database (p<0.0001). Expression of DNMT1 and DNMT3b was strongly upregulated in tumor tissue, but not correlated with MGMT promoter methylation and MGMT mRNA expression. CONCLUSIONS/SIGNIFICANCE: MGMT mRNA expression plays a direct role for mediating tumor sensitivity to alkylating agents. Discordant findings indicate methylation-independent pathways of MGMT expression regulation. DNMT1 and DNMT3b are likely to be involved in CGI methylation. However, their exact role yet has to be defined.