Screening and identification of differentially expressed microRNAs in diffuse large B-cell lymphoma based on microRNA microarray

MicroRNA Expression Profile in Bone Marrow and Lymph Nodes in B-Cell Lymphomas

Hodgkin's lymphomas (HL) and the majority of non-Hodgkin's lymphomas (NHL) derive from different stages of B-cell differentiation. MicroRNA (miRNA) expression profiles change during lymphopoiesis. Thus, miRNA expression analysis can be used as a reliable diagnostic tool to differentiate tumors. In addition, the identification of miRNA's role in lymphopoiesis impairment is an important fundamental task. The aim of this study was to analyze unique miRNA expression profiles in different types of B-cell lymphomas. We analyzed the expression levels of miRNA-18a, -20a, -96, -182, -183, -26b, -34a, -148b, -9, -150, -451a, -23b, -141, and -128 in lymph nodes (LNs) in the following cancer samples: HL (n = 41), diffuse large B-cell lymphoma (DLBCL) (n = 51), mantle cell lymphoma (MCL) (n = 15), follicular lymphoma (FL) (n = 12), and lymphadenopathy (LA) (n = 37), as well as bone marrow (BM) samples: HL (n = 11), DLBCL (n = 42), MCL (n = 14), FL (n = 16), and non-cancerous blood diseases (NCBD) (n = 43). The real-time RT-PCR method was used for analysis. An increase in BM expression levels of miRNA-26b, -150, and -141 in MCL (p < 0.01) and a decrease in BM levels of the miR-183-96-182 cluster and miRNA-451a in DLBCL (p < 0.01) were observed in comparison to NCBD. We also obtained data on increased LN levels of the miR-183-96-182 cluster in MCL (p < 0.01) and miRNA-18a, miRNA-96, and miRNA-9 in FL (p < 0.01), as well as decreased LN expression of miRNA-150 in DLBCL (p < 0.01), and miRNA-182, miRNA-150, and miRNA-128 in HL (p < 0.01). We showed that miRNA expression profile differs between BM and LNs depending on the type of B-cell lymphoma. This can be due to the effect of the tumor microenvironment.

Hsa_circ_0000877 facilitates the progression of diffuse large B-cell lymphoma by miR-370-3p/mitogen-activated protein kinase kinase kinase kinase 4/Hippo pathway

Diffuse large B-cell lymphoma (DLBCL) originates from B lymphocytes and is a fatal hematological malignancy. Circular RNAs have been increasingly reported as a promising biological target for cancer therapy, but their role in DLBCL remains poorly studied. Relative expression levels of has_circ_0000877 (circ_0000877), microRNA-370-3p (miR-370-3p), and mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) were assessed by quantitative real-time PCR. Western blot analysis was employed to measure protein levels. Cell Counting Kit-8 assay and 5-ethynyl-2'-deoxyuridine (EdU) assay were used to detect the proliferation of TMD8 and U2932 cells. Cell cycle and apoptosis were investigated by flow cytometry. Transwell assay was used to analyze cell migration and invasion. Molecular interaction was determined by dual-luciferase reporter assay and RNA immunoprecipitation assay. The protein expression of Ki67 in tumor tissues of mice was detected by immunohistochemistry assay. The expression of circ_0000877 was markedly elevated in DLBCL tissues and cell lines. The decreased expression of circ_0000877 significantly inhibited proliferation, migration, and invasion of DLBCL cell lines. In addition, silencing circ_0000877 promoted cell apoptosis and induced cell cycle arrest in G0/G1 phase. Then, miR-370-3p directly interacted with circ_0000877 and MAP4K4. Circ_0000877 promoted MAP4K4 level by sponging miR-370-3p. MAP4K4 depletion inhibited the activation of Hippo pathway. Finally, circ_0000877 silencing significantly prevented the growth of DLBCL cells in vivo . Our findings revealed that circ_0000877 could regulate the malignant evolution of DLBCL by miR-370-3p/MAP4K4/Hippo pathway.

hsa-MicroRNA-28-5p Inhibits Diffuse Large B-Cell Lymphoma Cell Proliferation by Downregulating 14-3-3ζ Expression

MicroRNAs (miRNAs) participate in the comprehensive biological process of several cancer types. In our former study, we found that hsa-microRNA- (miR-)28-5p was downregulated, but tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activating protein zeta (14-3-3ζ or YWHAZ) was upregulated in diffuse large B-cell lymphoma (DLBCL) tissues. We predicted that YWHAZ was a target gene for hsa-miR- 28-5p using bioinformatics analysis. Our goal was to reveal the role of hsa-miR-28-5p in DLBCL. YWHAZ was tested by immunohistochemistry (IHC) in formalin-fixed paraffin-embedded (FFPE) tissues of 137 DLBCL tissues, and the expression of hsa-miR-28-5p and YWHAZ was examined by quantitative real-time polymerase chain reaction (qRT-PCR) in 15 fresh and frozen DLBCL tissues. To study the functional roles of the downregulated hsa-miR-28-5p in DLBCL, a Cell Counting Kit-8 assay was conducted to estimate cell proliferation. Transient transfection of miRNA mimics was performed to overexpress hsa-miR-28-5p, and flow cytometry was performed to examine cell apoptosis and cell cycle progression. A dual-luciferase reporter assay was employed to explore the relationship between hsa-miR-28-5p and YWHAZ. Western blotting and qRT-PCR were used to investigate the function of hsa-miR-28-5p in YWHAZ expression. hsa-miR-28-5p was found to be significantly downregulated in DLBCL tissues and cell lines. Functional studies showed that hsa-miR-28-5p overexpression inhibited cell viability and proliferation, and YWHAZ was predicted to be a target of hsa-miR-28-5p. Dual-luciferase reporter assay, Western blotting, and qRT-PCR verified that hsa-miR-28-5p negatively regulated YWHAZ expression by directly targeting its 3′ untranslated regions in DLBCL cells. hsa-miR-28-5p may suppress the growth of DLBCL cells by inhibiting YWHAZ expression. These findings could provide novel targets for DLBCL diagnosis and therapy.