Upregulation of miR-23a approximately 27a approximately 24 decreases transforming growth factor-beta-induced tumor-suppressive activities in human hepatocellular carcinoma cells

Transforming growth factor-beta (TGF-beta) plays a dual and complex role in human cancer. In this report, we observe a specific set of MicroRNAs (miRNAs) changed in response to TGF-beta in human hepatocellular carcinoma (HCC) cells by miRNA microarray screening. A cluster of miRNA, miR-23a approximately 27a approximately 24, is induced in an early stage by TGF-beta in Huh-7 cells. Knockdown of Smad4, Smad2 or Smad3 expression by RNA interference can attenuate the response of miR-23a approximately 27a approximately 24 to TGF-beta addition, indicating that this induction is dependent on Smad pathway. We also explore that miR-23a approximately 27a approximately 24 can function as an antiapoptotic and proliferation-promoting factor in liver cancer cells. In addition, expression of this miRNA cluster is found to be remarkably upregulated in HCC tissues versus normal liver tissues. These findings suggest a novel, alternative mechanism through which TGF-beta could induce specific miRNA expression to escape from tumor-suppressive response in HCC cells.     

Changes in microRNA (miRNA) expression during pancreatic cancer development and progression in a genetically engineered KrasG12D;Pdx1-Cre mouse (KC) model

Differential expression of microRNAs (miRNAs) has been demonstrated in various cancers, including pancreatic cancer (PC). Due to the lack of tissue samples from early-stages of PC, the stage-specific alteration of miRNAs during PC initiation and progression is largely unknown. In this study, we investigated the global miRNA expression profile and their processing machinery during PC progression using the Kras^G12D;Pdx1-Cre (KC) mouse model. At 25 weeks, the miRNA microarray analysis revealed significant downregulation of miR-150, miR-494, miR-138, miR-148a, miR-216a, and miR-217 and upregulation of miR-146b, miR-205, miR-31, miR-192, and miR-21 in KC mice compared to controls. Further, expression of miRNA biosynthetic machinery including Dicer, Exportin-5, TRKRA, and TARBP2 were downregulated, while DGCR8 and Ago2 were upregulated in KC mice. In addition, from 10 to 50 weeks of age, stage-specific expression profiling of miRNA in KC mice revealed downregulation of miR-216, miR-217, miR-100, miR-345, miR-141, miR-483-3p, miR-26b, miR-150, miR-195, Let-7b and Let-96 and upregulation of miR-21, miR-205, miR-146b, miR-34c, miR-1273, miR-223 and miR-195 compared to control mice. Interestingly, the differential expression of miRNA in mice also corroborated with the miRNA expression in human PC cell lines and tissue samples; ectopic expression of Let-7b in CD18/HPAF and Capan1 cells resulted in downregulation of KRAS and MSST1 expression. Overall, the present study aids an understanding of miRNA expression patterns during PC pathogenesis and helps to facilitate the identification of promising and novel early diagnostic/prognostic markers and therapeutic targets.     

MicroRNA-regulated gene networks during mammary cell differentiation are associated with breast cancer

MicroRNAs (miRNAs) play pivotal roles in stem cell biology, differentiation and oncogenesis and are of high interest as potential breast cancer therapeutics. However, their expression and function during normal mammary differentiation and in breast cancer remain to be elucidated. In order to identify which miRNAs are involved in mammary differentiation, we thoroughly investigated miRNA expression during functional differentiation of undifferentiated, stem cell-like, murine mammary cells using two different large-scale approaches followed by qPCR. Significant changes in expression of 21 miRNAs were observed in repeated rounds of mammary cell differentiation. The majority, including the miR-200 family and known tumor suppressor miRNAs, was upregulated during differentiation. Only four miRNAs, including oncomiR miR-17, were downregulated. Pathway analysis indicated complex interactions between regulated miRNA clusters and major pathways involved in differentiation, proliferation and stem cell maintenance. Comparisons with human breast cancer tumors showed the gene profile from the undifferentiated, stem-like stage clustered with that of poor-prognosis breast cancer. A common nominator in these groups was the E2F pathway, which was overrepresented among genes targeted by the differentiation-induced miRNAs. A subset of miRNAs could further discriminate between human non-cancer and breast cancer cell lines, and miR-200a/miR-200b, miR-146b and miR-148a were specifically downregulated in triple-negative breast cancer cells. We show that miR-200a/miR-200b can inhibit epithelial-mesenchymal transition (EMT)-characteristic morphological changes in undifferentiated, non-tumorigenic mammary cells. Our studies propose EphA2 as a novel and important target gene for miR-200a. In conclusion, we present evidentiary data on how miRNAs are involved in mammary cell differentiation and indicate their related roles in breast cancer.     

miRNA在肺腺癌恶性胸腔积液中的表达及临床意义

目的 检测肺腺癌恶性胸腔积液中相关的miRNA表达,探讨miRNA表达与预后的关系。方法 采用miRNA芯片技术筛选10例肺腺癌患者恶性胸腔积液miRNA表达谱,结合临床分析可能与预后有关的miRNA。采用实时荧光定量PCR（QPCR）技术检测84例肺腺癌恶性胸腔积液标本中miRNA表达,结合临床预后分析确认表达差异的miRNA。结果 在5例无进展生存期（PFS）≥5个月和5例PFS≤2个月患者中,芯片筛查显示共13种miRNAs 表达变化倍数＞2倍。在84例不同预后肺腺癌胸腔积液患者中选取miR-146a、miR-16、miR-155、miR-484、miR-134、miR-141、miR-106b和miR-93共8个miRNA进行QPCR验证,发现仅miR-93和miR-146a表达存在差异（P＜0.05）,miR-93在预后好的患者中表达升高,变化倍数为2.41倍,miR-146a在预后好的患者中表达下降,变化倍数为0.46倍。结论 miR-93在预后好的患者恶性胸腔积液中高表达,miR-146a则相反,其可能成为判断肺癌恶性胸腔积液患者预后新的分子标志物。     

Exosomal microRNA: A Diagnostic Marker for Lung Cancer

BackgroundTo date, there is no screening test for lung cancer shown to affect overall mortality. MicroRNAs (miRNAs) are a class of small noncoding RNA genes found to be abnormally expressed in several types of cancer, suggesting a role in the pathogenesis of human cancer. Their accumulation within the peripheral circulation appears to be unique to cancer. The genome-wide expression profiling of miRNAs has been shown to be significantly different among primary lung cancers and corresponding noncancerous lung tissues. In studies demonstrating diagnostic miRNA signatures of NSCLC, specific miRNAs were overexpressed compared with normal lung tissue (miR-17-3p, miR-21, miR-106a, miR-146, miR-155, miR-191, miR-192, miR-203, miR-205, miR-210, miR-212, and miR-214). In this study, we evaluate the levels of circulating tumor exosomes, the circulating levels of exosomal small RNA, and specific exosomal miRNAs in patients with and without lung adenocarcinoma, correlating the levels with the American Joint Committee on Cancer (AJCC) stage of disease to validate it as an acceptable marker for diagnosis and prognosis in patients with adenocarcinoma of the lung.Patients and MethodsPlasma from patients with lung adenocarcinoma and a control group without known lung cancer or other active cancer were collected. Exosomes were isolated from plasma samples by a 2-step procedure using size-exclusion chromatography and magnetic activated cell sorting (MACS). Plasma samples (1 mL) were separated on Sepharose 2B, monitoring elution at 280 nm, and using a modified MACS procedure, exosomes of tumor origin were isolated using anti—epithelial cell adhesion molecule. Small RNA was isolated from circulating tumor exosomes using mirVana isolation kit (Ambion, Austin, TX) and this low molecular RNA enriched fraction was used for miRNA profiling as defined by microarray analysis. Low molecular weight RNA (5 μg) was used for hybridization on miRNA microarray chips. These miRNA were identified as hsa-miR-17-3p, hsa-miR-21, hsa-miR-106a, hsa-miR-146, hsa-miR-155, miR-191, miR-192, miR-203, miR-205, miR-210, miR212, and hsa-miR-214.ResultsTo date, 28 patients and 9 controls, AJCC stages I-IV, ages 21–80 years, were enrolled in the study. Exosome concentration ranged from 1.02–9.24 mg/mL for the lung adenocarcinoma group versus 0.62–1.7 mg/mL in the control group. The total miRNA concentration ranged from 131.1–275 ug/mL for the lung adenocarcinoma group versus 44.9–131.1 ug/mL in the control group. The mean exosome value in the lung cancer group was 2.85 mg/mL (CI, 1.94–3.76) and 0.77 mg/mL (CI, 0.68–0.86; P < .001). The mean RNA value in the lung cancer group was 158.6 ug/mL (CI, 145.7–171.5) and 68.1 ug/mL (CI, 57.2–78.9; P < .001). The only patient in the control group who had an exosome concentration > 1.0 mg/mL and RNA concentration > 100 ug/mL had a history of vulvar cancer without evidence of active disease. No correlation between the levels and the stage of disease was found. To compare the presence of specific miRNAs between tumors and their corresponding circulating exosomes, miRNA fractions were isolated and profiled from circulating tumor exosomes and the original tumor. MicroRNA profiling was performed in duplicate, using microarrays containing probes for 467 human mature miRNA. Comparisons between peripheral circulation-derived exosomes and tumors indicated that the miRNA signatures were not significantly different. This approach confirmed that the 12 specific miRNA were elevated in NSCLC and that the associations of these 12 were mirrored in the circulating exosomes. The levels of tumor-derived miRNA profiles exhibited a strong correlation with the levels of peripheral blood-derived exosomal miRNAs (for miR-17-3p, r = 0.76; miR-21, r = 0.77; miR-146, r = 0.88; miR-155, r = 0.85; miR-191, r = 0.83; miR-203, r = 0.85; miR-205, r = 0.91; and miR-214, r = 0.71).ConclusionThe significant difference in total exosome and miRNA levels between patients with lung cancer and controls suggests that exosomal miRNA is a screening test for lung adenocarcinoma. There is no obvious correlation between the total exosomal miRNA levels and stage of disease; however, it has been suggested in miRNA profiling studies of tumor tissue, that miRNA expression might be critical for the development of cancer but not for its progression. If specific miRNA levels predict response to treatment and can add prognostic information in addition to conventional staging needs further study. While validation studies will be necessary before bypassing the use with tumor mass biopsies, the use of exosomal miRNA profiling could extend this approach to screening of asymptomatic individuals as well as for monitoring disease recurrence.     

UVA-induced cell cycle progression is mediated by a disintegrin and metalloprotease/epidermal growth factor receptor/AKT/Cyclin D1 pathways in keratinocytes

UVA (315-400 nm), which constitutes approximately 95% of the UV irradiation in natural sunlight, represents a major environmental challenge to the skin and is clearly associated with human skin cancer. Here, we show that a low, nonlethal dose of UVA induces dose-dependent cell cycle progression in human HaCaT keratinocytes. We found that UVA induced cyclin D1 accumulation, whereas siRNA knockdown of cyclin D1 blocked the UVA-induced cell cycle progression, indicating that this process is mediated by cyclin D1. UVA irradiation also induced AKT activation; when cells were incubated with phosphatidylinositol-3-OH kinase/AKT inhibitor or infected with dominant-negative AKT, cyclin D1 up-regulation, cell cycle progression, and proliferation were inhibited, suggesting that AKT activation is required for UVA-induced cell cycle progression. In contrast, extracellular signal-regulated kinase (ERK) was not activated by UVA exposure; incubation with ERK/mitogen-activated protein kinase inhibitor had no effect on UVA-induced cyclin D1 up-regulation and cell cycle progression. Activation of epidermal growth factor receptor (EGFR) was observed after UVA exposure. EGFR kinase inhibitor AG attenuated the UVA-induced AKT/cyclin D1 pathway and cell cycle progression, indicating that EGFR is upstream of AKT/cyclin D1 pathway activation. Furthermore, metalloprotease inhibitor GM6001 blocked UVA-induced cell cycle progression, and siRNA knockdown of a disintegrin and metalloprotease (ADAM)17 had a similar inhibitory effect, demonstrating that ADAM17 mediates the EGFR/AKT/cyclin D1 pathway and cell cycle progression to the S phase induced by UVA radiation. Identification of these signaling pathways in UVA-induced cell proliferation will facilitate the development of efficient and safe chemopreventive and therapeutic strategies for skin cancer.     

MiR-23a regulates TGF-β-induced epithelial-mesenchymal transition by targeting E-cadherin in lung cancer cells

Transforming growth factor-β (TGF-β)-induced epithelial-mesenchymal transition (EMT) has been shown to be related to the pathogenesis of various diseases including lung cancer. Recently, microRNAs (miRNA) have been recognized as a new class of genes involved in human tumorigenesis. MiR-23a/24/27a is a miRNA cluster located in chromosome 19p13.12, which can function as an oncogene in several human cancers. In this study, we analyzed miR-23a/24/27a expression in 10 non-small cell cancer (NSCLC) cell lines by real-time PCR analysis. Correlation between expression of these miRNAs and TGF-β/Smad signaling was evaluated. We found that miR-23a could be regulated by TGF-β1 in a Smad-dependent manner in A549 lung adenocarcinoma cells showing the EMT phenomenon. Knockdown of miR-23a partially restored E-cadherin expression under conditions of TGF-β1 stimulation. In contrast, overexpression of miR-23a could suppress E-cadherin expression and stimulate EMT. Furthermore, A549 cells with overexpressed miR-23a were more resistant to gefitinib compared to the parental cells. These findings suggest that miR-23a regulates TGF-β-induced EMT by targeting E-cadherin in lung cancer cells and may be useful as a new therapeutic target in NSCLC.     

MiR-200b and miR-155 as predictive biomarkers for the efficacy of chemoradiation in locally advanced head and neck squamous cell carcinoma

BackgroundThe predictive value of microRNAs (miRNAs) in tumour cells and infiltrating immune cells for the efficacy of chemoradiation (CRTX) in locally advanced head and neck squamous cell carcinoma (HNSCC) was evaluated.MethodsFormalin-fixed, paraffin-embedded tumour material was collected from patients with locally advanced HNSCC treated within the ARO-0401 phase III trial with radiotherapy in combination with either 5-fluorouracil/cisplatin (CDDP-CRTX) or 5-fluorouracil/mitomycin C (MMC-CRTX). MiRNA and immune profiles were established in a test cohort of 48 oropharyngeal carcinoma (OPSCC) cases by Affymetrix miRNA microarrays and the nanoString PanCancer Immune Panel, respectively. Expression of miRNA candidates was measured in 149 HNSCC patients by real-time PCR. Interference of miRNA profiles with CRTX efficacy was determined by Kaplan–Meier and Cox regression analysis.ResultsExpression levels of five miRNAs (miR-27b, -130b, -200b, -451 and -532-5p) were significantly associated with overall survival after MMC-CRTX. Six different miRNAs (miR-125b, -146a, -150, -155, -187 and -342-5p) were correlated with overall survival after CDDP-CRTX. Validation by real-time PCR confirmed the predictive value of miR-200b and miR-155 in OPSCC, which was absent in hypopharyngeal carcinomas. MiR-146a was revealed as a prognostic marker for both CRTX regimens. MiR-200b expression was mainly associated with distant metastasis, whereas miR-155 correlated with local recurrence. MiR-155 and miR-146a were identified as surrogate markers for tumour-infiltrating lymphocytes.ConclusionsMiR-200b and miR-155 were established as potential markers for personalised treatment selection of two standard regimens of CRTX. The predictive role of miR-155 deserves further investigation, especially within the framework of clinical trials of CRTX/immune checkpoint inhibitor combinations.     

MicroRNA-146a constrains multiple parameters of intestinal immunity and increases susceptibility to DSS colitis

Host-microbial interactions within the mammalian intestines must be properly regulated in order to promote host health and limit disease. Because the microbiota provide constant immunological signals to intestinal tissues, a variety of regulatory mechanisms have evolved to ensure proper immune responses to maintain homeostasis. However, many of the genes that comprise these regulatory pathways, including immune-modulating microRNAs (miRNAs), have not yet been identified or studied in the context of intestinal homeostasis. Here, we investigated the role of microRNA-146a (miR-146a) in regulating intestinal immunity and barrier function and found that this miRNA is expressed in a variety of gut tissues in adult mice. By comparing intestinal gene expression in WT and miR-146a−/− mice, we demonstrate that miR-146a represses a subset of gut barrier and inflammatory genes all within a network of immune-related signaling pathways. We also found that miR-146a restricts the expansion of intestinal T cell populations, including Th17, Tregs, and Tfh cells. GC B cells, Tfh ICOS expression, and the production of luminal IgA were also reduced by miR-146a in the gut. Consistent with an enhanced intestinal barrier, we found that miR-146a−/− mice are resistant to DSS-induced colitis, a model of Ulcerative Colitis (UC), and this correlated with elevated colonic miR-146a expression in human UC patients. Taken together, our data describe a role for miR-146a in constraining intestinal barrier function, a process that alters gut homeostasis and enhances at least some forms of intestinal disease in mice.     

肠炎和肠炎相关结直肠癌miRNA表达检测及生物信息学分析

背景与目的：炎症性肠病(inflammatory bowel diseases,IBD)为一组慢性肠道疾病,包括溃疡性结肠炎(ulcerative colitis,UC)与克罗恩病(Crohn’s disease,CD)。肠炎相关性结直肠癌(colitis-associated col-orectal cancers,CAC)是由IBD癌化形成的一种恶性肿瘤。该研究通过检测UC、CD和CAC组织中相关微小核糖核酸(miRNA)的水平,初步探讨其作为肠炎癌转化分子标志物的可能性,并对在肠炎和CAC中显著变化的一组miRNAs进行靶基因归集和生物信息学分析,为以miRNAs为靶点的基因治疗提供理论和实验基础。方法：采用实时荧光定量聚合酶链反应(real-time lfuorescent quantitative polymerase chain reaction,RTFQ-PCR)技术,检测13例UC组织、3例CD患者组织、12例CAC组织及8例正常肠组织中16种miRNAs的表达。通过生物信息学对显著变化的一组miRNA进行靶基因分析,将文献中已报导的所有靶基因进行汇总,并利用DAVID数据库对靶基因进行功能富集分析(GO-analysis)和信号转导通路富集分析(KEGG-analysis,BIOCARTA-analysis)。结果：炎症相关miR-146a和癌症相关miR-27a、miR-29a、miR-20a、miR-21在UC、CD和CAC中的表达都显著高于正常结肠组织,且这一组miRNA的靶基因都富集在癌症相关通路、免疫信号相关通路和炎癌转换相关通路上。结论：miR-146a、miR-27a、miR-29a、miR-20a和miR-21可能是参与肠炎向结直肠癌转化的一组miRNA。     

Therapeutic Potential of an Anti-diabetic Drug,Metformin:Alteration of miRNA expression in Prostate Cancer Cells

Background and Aims: Prostate cancer is the most commonly diagnosed cancer in males in many populations.Metformin is the most widely used anti-diabetic drug in the world, and there is increasing evidence of a potentialefficacy of this agent as an anti-cancer drug. Metformin inhibits the proliferation of a range of cancer cellsincluding prostate, colon, breast, ovarian, and glioma lines. MicroRNAs (miRNAs) are a class of small, noncoding,single-stranded RNAs that downregulate gene expression. We aimed to evaluate the effects of metformintreatment on changes in miRNA expression in PC-3 cells, and possible associations with biological behaviour.Materials and Methods: Average cell viability and cytotoxic effects of metformin were investigated at 24 hourintervals for three days using the xCELLigence system. The IC50 dose of metformin in the PC-3 cells was foundto be 5 mM. RNA samples were used for analysis using custom multi-species microarrays containing 1209probes covering 1221 human mature microRNAs present in miRBase 16.0 database. Results: Among the humanmiRNAs investigated by the arrays, 10 miRNAs were up-regulated and 12 miRNAs were down-regulated in themetformin-treated group as compared to the control group. In conclusion, expression changes in miRNAs ofmiR-146a, miR-100, miR-425, miR-193a-3p and, miR-106b in metformin-treated cells may be important. Thisstudy may emphasize a new role of metformin on the regulation of miRNAs in prostate cancer.     

Hematopoietic-specific microRNA expression in human cells

We examined expression profiles of hematopoietic tissue-specific microRNAs (miRNAs; miR-142, miR-155, miR-181 and miR-223) in 17 commercially available malignant hematopoietic cell lines and compared to those in highly purified normal human B, T, monocytic and granulocytic lineages. Although malignant cell lines examined showed miRNA expression patterns similar to normal human hematopoietic lineages, the levels of miRNA expression among cell lines and normal cell lineages were considerably different, indicating the significance of miRNAs in human hematopoietic diseases. Further our results showed differences in miRNA expression between mouse and human hematopoietic cells, suggesting important regulatory roles of miRNAs in human hematopoiesis and oncogenesis.     

MicroRNAs and immunity: novel players in the regulation of normal immune function and inflammation

The discovery of microRNAs (miRNAs) is one of the major scientific breakthroughs in recent years and has revolutionized the way we look at gene regulation. Although we are still at a very early stage in understanding their impact on immunity, miRNAs are changing the way we think about the development of the immune system and regulation of immune functions. MiRNAs are implicated in establishing and maintaining the cell fate of immune cells (e.g. miR-181a and miR-223), and they are involved in innate immunity by regulating Toll-like receptor signaling and ensuing cytokine response (e.g. miR-146). Moreover, miRNAs regulate central elements of the adaptive immune response such as antigen presentation (e.g. miR-155) and T cell receptor signaling (miR-181a). Recent evidence showing altered miRNA expression in chronic inflammatory diseases (e.g. miR-203 and miR-146) suggests their involvement in immune-mediated diseases. Furthermore, miRNAs have been implicated in viral immune escape and anti-viral defense (e.g. miR-196). In this review, we will summarize the latest findings about the role of miRNAs in the development of the immune system and regulation of immune functions and inflammation.     

Overexpression of miR-370 and downregulation of its novel target TGFβ-RII contribute to the progression of gastric carcinoma

MicroRNAs (miRNAs) are endogenous non-coding RNAs that are known to be involved in the pathogenesis of tumors. Gastric carcinoma (GC) is a common malignancy worldwide. The aim of this study was the identification of the expression signature and functional roles of aberrant miRNAs in GC. Initial screening established a profile of aberrantly expressed miRNAs in tumors. miR-370 was confirmed to be overexpressed in GC tissues. Higher expression of miR-370 in GC tissues was associated with more advanced nodal metastasis and a higher clinical stage compared with controls. In addition, significantly higher level of miR-370 was noted in the plasma of GC patients compared with controls. Patients having more invasive or advanced tumors also exhibited a higher plasma level of miR-370. In vitro assays indicated that exogenous miR-370 expression enhanced the oncogenic potential of GC cells. The AGS-GFPM2 cells with exogenous miR-370 expression also exhibited enhanced abdominal metastatic dissemination in nude mice. Reporter assays confirmed that miR-370 targeted predicted sites in 3'UTR of transforming growth factor-β receptor II (TGFβ-RII) gene. The exogenous miR-370 expression decreased TGFβ-RII expression and the phosphorylation of Smad3 elicited by TGFβ1. The TGFβ1-mediated repression in cell migration was reverted by exogenous miR-370 expression. A reverse correlation between miR-370 and TGFβ-RII expression was noted in GC tissues. This study concludes that miR-370 is a miRNA that is associated with GC progression by downregulating TGFβ-RII. The miRNA expression profile described in this study should contribute to future studies on the role of miRNAs in GC.     

Differential micro-RNA expression in primary CNS and nodal diffuse large B-cell lymphomas

Most primary CNS lymphomas (PCNSL) are diffuse large B-cell lymphomas (DLBCL). However, clinical behavior and prognosis differ considerably from those for nodal DLBCL (nDLBCL), and their pathogenesis is still not fully understood. Micro-RNAs (miRNAs) have been associated with cancer development and progression. We investigated a large miRNA panel for differential expression in PCNSL and nDLBCL, to determine new mechanisms potentially involved in PCNSL pathogenesis. Using paraffin-embedded biopsy specimens from 21 HIV-negative patients with newly diagnosed PCNSL (n = 11) and nDLBCL (n= 10), we measured the expression of 365 miRNA species by quantitative real-time PCR using low-density PCR arrays. We found that 18 miRNAs were differentially expressed: median expression levels of 13 miRNAs were 2.1-13.1 times higher in PCNSL, and median expression levels of 5 miRNAs were 2.6-3.3 times higher in nDLBCL. MiRNAs upregulated in PCNSL were associated with the Myc pathway (miR-17-5p, miR-20a, miR-9), with blocking of terminal B-cell differentiation (miR-9, miR-30b/c), or with upregulation by inflammatory cytokines (miR-155). Putative tumor-suppressor miRNAs (miR-199a, miR-214, miR-193b, miR-145) were downregulated in PCNSL. There was no overlap of miRNAs dysregulated in PCNSL with those differentially expressed between immunohistologically defined germinal center B cell-like (GCB) and non-GCB types or, apart from miR-9, with miRNAs known to be overexpressed in human brain. We conclude that PCNSL exhibits a distinct pattern of miRNA expression compared with nDLBCL. This argues for the involvement of different molecular mechanisms in the pathogenesis of these two lymphoma types.