miR-34a is a transcriptional target of p53 and implicated in carcinogenesis. We studied the role of miR-34a methylation in a panel of hematological malignancies including acute leukemia [acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL)], chronic leukemia [chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML)], multiple myeloma (MM) and non-Hodgkin's lymphoma (NHL). The methylation status of miR-34a promoter was studied in 12 cell lines and 188 diagnostic samples by methylation-specific polymerase chain reaction. miR-34a promoter was unmethylated in normal controls but methylated in 75% lymphoma and 37% myeloma cell lines. Hypomethylating treatment led to re-expression of pri-miR-34a transcript in lymphoma cells with homozygous miR-34a methylation. In primary samples at diagnosis, miR-34a methylation was detected in 4% CLL, 5.5% MM samples and 18.8% of NHL at diagnosis but none of ALL, AML and CML (P = 0.011). In MM patients with paired samples, miR-34a methylation status remained unchanged at progression. Amongst lymphoid malignancies, miR-34a was preferentially methylated in NHL (P = 0.018), in particular natural killer (NK)/T-cell lymphoma. In conclusion, amongst hematological malignancies, miR-34a methylation is preferentially hypermethylated in NHL, in particular NK/T-cell lymphoma, in a tumor-specific manner, therefore the role of miR-34a in lymphomagenesis warrants further study.

Background. Circular RNAs (circRNAs) are frequently dysregulated in cancers and are implicated in tumorigenesis and tumor progression. In this study, we investigated the role of circZNF91 in regulating the malignant phenotype of chronic lymphocytic leukemia (CLL) cells and the underlying molecular mechanism. Material/Methods. The expression of circZNF91 was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The binding sequences between circZNF91/miR-1283 and miR-1283/WEE1 were predicted by the bioinformatic database. The functional interactions were confirmed by the dual-luciferase reporter, RT-qPCR, and Western blot assays. The functional roles of the circZNF91/miR-1283/WEE1 axis in CLL progression were examined by cell proliferation, apoptosis, and EdU incorporation assays. Results. circZNF91 was upregulated in CLL samples. Silencing circZNF91 attenuated CLL cell proliferation and induced apoptosis and cell cycle arrest. circZNF91 could sponge miR-1283 to suppress its activity, which in turn upregulated WEE1 expression. Silencing circ-TTBK2 reduced WEE1 expression, while the inhibitor of miR-1283 enhanced WEE1 expression. The miR-1283/WEE1 axis mediated the effects of circZNF91 on cell proliferation and apoptosis, as well as induced cell cycle regulation. Conclusions. The circZNF91/miR-1283/WEE1 axis is engaged in the pathological phenotypes of CLL cells, which could serve as potential targets for future therapy development.

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Object. In this study, bioinformatics analysis of differentially expressed genes (DEGs) and signaling pathway activities in different progression stages of chronic lymphocytic leukemia (CLL) and pre- and post-chemoimmunotherapy (CIT) treatment was performed. This may provide novel ideas for molecular diagnosis and individualized treatment strategies for CLL patients. Methods. Data from single-cell RNA sequencing (RNA-seq) of CLL patients were obtained from the Gene Expression Omnibus database. The R package was utilized to analyze the data, and the relation of results was predicted via the GeneMANIA website. The information of 7 samples covered three stages: observation stage, pretreatment by CIT with rituximab, fludarabine, and cyclophosphamide (pre-CIT), and post-CIT. The differentially expressed genes (DEGs) were identified, and functional enrichment analyses were performed. B cell subpopulations and pseudotime trajectories analysis was conducted. Results. A total of 70,659 DEGs were identified. Each patient’s DEGs presented their own characteristics, with low similarity. Therefore, it is difficult to identify potential hub genes. Similarly, pathway enrichment analysis showed significant tumor heterogeneity among CLL patients. Analysis of relapsed post-CIT compared to the observation stage suggested that the TP53 pathway should be taken seriously as it is closely related to treatment strategy and patient prognosis. Conclusions. Tumor heterogeneity may be a more common manifestation of CLL. Individualized treatment should be considered for CLL. TP53 abnormality and its regulatory factors should still be the focus of CLL diagnosis and treatment.