Abnormal expression and methylation of PRR34-AS1 are associated with adverse outcomes in acute myeloid leukemia

lncRNA PRR34-AS1 knockdown represses neuroinflammation and neuronal death in traumatic brain injury by inhibiting microRNA-498 expression

OBJECTIVE

Traumatic brain injury (TBI) can result in motor and cognitive dysfunction and is a possible risk factor for the subsequent development of dementia. However, the pathogenesis of TBI remains largely unclear. This study investigated the roles of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in inflammation and neuronal apoptosis following TBI.

METHODS

The lncRNA expression profiles in the cerebral cortices of TBI model mice and sham-operated mice were analyzed using microarray. We focused on an upregulated lncRNA, PRR34-AS1, because of its known modulatory role in apoptosis and inflammation.

RESULTS

Our findings indicated that the knockdown of PRR34-AS1 inhibited inflammation and neuronal apoptosis and improved long-term neurological function. Using an in vitro, cell-based model of etoposide-induced primary cortical neuronal injury, we demonstrated that PRR34-AS1 levels were higher in injured model cells than in untreated control cells. Silencing of PRR34-AS1 suppressed etoposide-induced apoptosis and the production of inflammatory mediators in primary cortical neurons. PRR34-AS1 directly targets microRNA-498 (miR-498) in primary cortical neurons. Importantly, the inhibition of miR-498 expression counteracted the effects of PRR34-AS1 silencing on neuronal apoptosis and inflammation.

CONCLUSIONS

These findings indicate that PRR34-AS1 may be a useful therapeutic target for TBI.

Abnormal GRHL2 Methylation Confers Malignant Progression to Acute Leukemia

Purpose

Abnormal methylation of Grainyhead-like 2 (GRHL2) is associated with a substantial role in the malignant phenotype of tumor patients. Our present research is aimed at studying the abnormal expression of GRHL2 and the association of methylation in patients with acute leukemia and its relationship with prognosis.

Materials and Methods

We used quantitative real-time polymerase chain reaction (qRT-PCR) for detecting the aberrant expression level of GRHL2 in 60 patients with acute leukemia and 60 normal controls. We analyzed the significant correlation between the expression level of GRHL2 with clinicopathological features and patients' prognosis in acute leukemia using the corresponding statistical methods. Secondly, we employed qRT-PCR and Western blotting to detect the mRNA and protein levels of GRHL2 in leukemia cell lines. Next, we used methylation-specific polymerase chain reaction (MSP) technology for detecting the methylation of GRHL2 in clinical samples with acute leukemia and cell lines. Then we investigated the demethylating effect of arsenic trioxide and 5-azacitidine on the mRNA and protein expression levels of GRHL2 in cell lines of acute leukemia. Finally, we studied the effects of arsenide trioxide and 5-azacitidine on the proliferation of leukemia cells and the TGF-β signaling pathway.

Results

We found a lower level of GRHL2 expression not only in acute leukemia patients but also in cell lines when compared with normal controls. At the same time, the expression level of GRHL2 in patients with acute leukemia was significantly correlated with leukocyte count, platelet count, and cytogenetic risk grouping. In addition, the lower GRHL2 expression group showed a significantly lower overall survival rate in acute leukemia patients than that of patients with a higher GRHL2 expression group. Univariate and multivariate analyses revealed that the expression of GRHL2 is an independent risk factor in acute leukemia patients. The methylation level of the GRHL2 promoter region in acute leukemia patients and cell lines was significantly higher than the normal control group, and we found the elevated mRNA and protein levels of GRHL2 in acute leukemia cell lines after the use of the demethylation drug arsenic trioxide and 5-azacitidine. At the same time, arsenide trioxide and 5-azacitidine are associated with the inhibition of cellular proliferation of acute leukemia cells and also promote the elevated expression of TGF-β signaling pathway-linked proteins, including TGF-β, Smad2, Smad3, and Smad4.

Conclusion

Increased expression and methylation level of GRHL2 are closely associated with the prognosis and malignant phenotype of acute leukemia patients and play an irreplaceable role in the occurrence and development of patients with acute leukemia.

Abnormal expression and methylation of PRR34-AS1 are associated with adverse outcomes in acute myeloid leukemia

It was previously reported that PRR34‐AS1 was overexpressed in some solid tumors. PRR34‐AS1 promoter was shown to have a differential methylation region (DMR), and was hypomethylated in acute myeloid leukemia (AML). Therefore, the present study used real‐time quantitative PCR (RQ‐PCR) to explore the expression characteristics of PRR34‐AS1 in AML. In addition, the correlation between the expression of PRR34‐AS1 and clinical prognosis of AML was determined. The findings of this study indicated that high PRR34‐AS1 expression was bound up with shorter overall survival (OS) in AML patients (p = 0.002). Moreover, patients with high expression of PRR34‐AS1 had significantly lower complete remission (CR) rate compared with those with low expression of PRR34‐AS1 after induction chemotherapy. Furthermore, multivariate analysis confirmed that PRR34‐AS1 expression was an independent factor affecting CR in whole‐AML, non‐APL‐AML, and CN‐AML patients (p = 0.032, 0.039, and 0.036, respectively). Methylation‐specific PCR (MSP) and bisulfite sequencing PCR (BSP) were used to explore the methylation status of PRR34‐AS1. PRR34‐AS1 promoter showed a pattern of hypomethylation in AML patients compared with normal controls (p = 0.122). Notably, of whole‐AML and non‐APL‐AML patients, PRR34‐AS1 hypomethylated patients presented a significantly shorter OS than those with a hypermethylated PRR34‐AS1 (p = 0.010 and 0.037, respectively). Multivariate analysis confirmed that the hypomethylation of PRR34‐AS1 served as an independent prognostic indicator in both whole‐cohort AML and non‐APL‐AML categories (p = 0.057 and 0.018, respectively). In summary, the findings of this study showed that abnormalities in PRR34‐AS1 are associated with poor prognosis in AML. Therefore, monitoring this index may be important in the prognosis of AML and can provide information on effective chemotherapy against the disease.