DOK6 promoter methylation serves as a potential biomarker affecting prognosis in de novo acute myeloid leukemia

Targeting DNA Methylation in Leukemia, Myelodysplastic Syndrome, and Lymphoma: A Potential Diagnostic, Prognostic, and Therapeutic Tool

DNA methylation represents a crucial mechanism of epigenetic regulation in hematologic malignancies. The methylation process is controlled by specific DNA methyl transferases and other regulators, which are often affected by genetic alterations. Global hypomethylation and hypermethylation of tumor suppressor genes are associated with hematologic cancer development and progression. Several epi-drugs have been successfully implicated in the treatment of hematologic malignancies, including the hypomethylating agents (HMAs) decitabine and azacytidine. However, combinations with other treatment modalities and the discovery of new molecules are still the subject of research to increase sensitivity to anti-cancer therapies and improve patient outcomes. In this review, we summarized the main functions of DNA methylation regulators and genetic events leading to changes in methylation landscapes. We provide current knowledge about target genes with aberrant methylation levels in leukemias, myelodysplastic syndromes, and malignant lymphomas. Moreover, we provide an overview of the clinical trials, focused mainly on the combined therapy of HMAs with other treatments and its impact on adverse events, treatment efficacy, and survival rates among hematologic cancer patients. In the era of precision medicine, a transition from genes to their regulation opens up the possibility of an epigenetic-based approach as a diagnostic, prognostic, and therapeutic tool.

Dysregulation of LINC00324 associated with methylation facilitates leukemogenesis in de novo acute myeloid leukemia

INTRODUCTION

LINC00324 was overexpressed and facilitated carcinogenesis in various solid malignant tumors. However, the role of LINC00324 in leukemogenesis remains to be elucidated.

METHODS

The relative expression and unmethylation levels of LINC00324 were detected by real-time quantitative PCR (RT-qPCR) and real-time quantitative methylation-specific PCR (RT-qMSP). Cell proliferation experimental and flow cytometer (FCM) was used to detect the change of proliferation and apoptosis in leukemia cell lines after overexpression of LINC00324.

RESULTS

The results showed that the expression of LINC00324 and the methylation level of the promoter region were significantly negatively correlated in AML patients. Moreover, patients with lower LINC00324 expression showed more prolonged overall survival (OS). Remarkably, overexpression of LINC00324 in leukemia cell lines promoted the proliferation of target cells and inhibited their apoptosis.

CONCLUSION

Our findings firstly identified that the hypomethylation of LINC00324 was a common molecular event in de novo AML patients. The abnormally upregulated LINC00324 promotes proliferation and inhibits apoptosis in leukemia cells.

Methylation-independent CRIP1 expression is a potential biomarker affecting prognosis in cytogenetically normal acute myeloid leukemia

Abnormal expression of CRIP1 has been identified in numerous solid tumors. However, CRIP1 expression and its regulation are little known in acute myeloid leukemia (AML). The purpose of this study was to evaluate the expression and regulation of CRIP1 and the clinical implications of CRIP1 aberration in AML. Real-time quantitative PCR was carried out to detect the level of CRIP1 expression in 138 AML patients and 38 controls. CRIP1 methylation was detected by methylation-specific PCR and bisulfite sequencing PCR. Five public available AML datasets from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were further analyzed. The level of CRIP1 expression was up-regulated in AML patients compared with controls (P = 0.045). CRIP1 ^high patients had a significantly lower complete remission (CR) rate than CRIP1 ^low patients (P = 0.020). CRIP1 ^high group had a shorter overall survival (OS) and leukemia-free survival (LFS) than CRIP1 ^low group in cytogenetically normal AML (CN-AML) patients (P = 0.007 and 0.012, respectively). Multivariate analysis further confirmed that high CRIP1 expression was an independent risk factor for LFS in CN-AML patients (P = 0.005). However, we found that CRIP1 expression was not associated with the status of its promoter, which was nearly fully unmethylated both in controls and AML patients. Furthermore, our results were validated using the published GEO datasets and TCGA datasets. Our findings suggest that high CRIP1 expression is independently related with unfavorable prognosis in CN-AML.

DOK6 promoter methylation serves as a potential biomarker affecting prognosis in de novo acute myeloid leukemia

BACKGROUND

Downstream of tyrosine kinase 6 (DOK6), which is specifically expressed in the nervous system, was previously recognized as an adapter only in neurite outgrowth. Recent studies also demonstrated the potential role of DOK6 in solid tumors such as gastric cancer and breast cancer. However, previous studies of DOK6 have not dealt with its roles in myeloid malignancies. Herein, we verified the promoter methylation status of DOK6 and further explored its clinical implication in de novo acute myeloid leukemia (AML).

METHODS

A total of 100 newly diagnosed adult AML patients were involved in the current study. DOK6 expression and methylation were detected by real-time qPCR and methylation-specific PCR (MSP), respectively. Bisulfite sequencing PCR (BSP) was performed to assess the methylation density of the DOK6 promoter.

RESULTS

Downstream of tyrosine kinase 6 promoter methylation was significantly increased in AML patients compared to controls (P = .037), whereas DOK6 expression significantly decreased in AML patients (P < .001). The expression of DOK6 was markedly up-regulated after treated by 5-aza-2'-deoxycytidine (5-aza-dC) in THP-1 cell lines. The methylation status of the DOK6 promoter was associated with French-American-British classifications (P = .037). There was no significant correlation existed between DOK6 expression and its promoter methylation (R = .077, P = .635). Interestingly, of whole-AML and non-APL AML patients, both have a tendency pertaining to the DOK6 methylation group and a significantly longer overall survival (OS) than the DOK6 unmethylation group (P = .042 and .036, respectively).

CONCLUSION

Our study suggested that DOK6 promoter hypermethylation was a common molecular event in de novo AML patients. Remarkably, DOK6 promoter methylation could serve as an independent and integrated prognostic biomarker not only in non-APL AML patients but also in AML patients who are less than 60 years old.