Effect of COVID-19 infection on the gastrointestinal tract considering preventive methods during endoscopic procedures

Objectives

This study aimed to prevent the infection risk of environmental contamination by feces during endoscopic procedures. We evaluated the effect of coronavirus disease 2019 (COVID-19) on the gastrointestinal tract using fecal polymerase chain reaction (PCR) and examined risk factors affecting endoscopic procedures, to develop infection prevention strategies.

Methods

This single-center prospective observational study enrolled 32 patients diagnosed with COVID-19 at Tokyo Medical University Hospital between January and December 2022. We performed reverse transcriptase-PCR to detect severe acute respiratory syndrome coronavirus 2 in human stool specimens and evaluated the COVID-19 positivity rate in stool, the effect of vaccination on infection detection, and differences in positivity rates considering different patient backgrounds.

Results

Among the 32 nasal PCR-positive patients who underwent fecal PCR testing, the fecal PCR positivity rate was 21.8%. Compared to the negative cases, 71.4% vs. 32% were older than 65 years (p < 0.016), 71.4% vs. 0.8% (p < 0.001) had malignant tumors, the rate during BA.5 variant outbreaks was significantly higher (100% vs. 60% [p = 0.044]), and the rate of diarrheal symptoms was also higher (42.9% vs. 24%). The median collection period for fecal PCR-positive cases was 2 days after sampling.

Conclusions

The severe acute respiratory syndrome coronavirus 2 affects not only the upper respiratory tract but also the gastrointestinal tract. These findings may indicate the risk of digestive fluid infection in older patients with gastrointestinal symptoms and immunocompromised patients with malignant tumor comorbidities, especially during the early stages of viral infection. Therefore, it is advisable to establish a system to prevent infection by using personal protective equipment, including eye guards, in future endoscopic procedures.

Plasma extracellular vesicle microRNAs reflecting the therapeutic effect of the CBP/β-catenin inhibitor PRI-724 in patients with liver cirrhosis

There is an unmet need for antifibrotic therapies to prevent the progression of liver cirrhosis. Previously, we conducted an exploratory trial to assess the safety and antifibrotic efficacy of PRI-724, a selective CBP/β-catenin inhibitor, in patients with liver cirrhosis. PRI-724 was well tolerated and exerted a potential antifibrotic effect. Here, we investigated whether the profiles of circulating microRNAs packaged in extracellular vesicles (EV-miRNAs) are associated with responses to liver fibrosis treatments. Eighteen patients who received PRI-724 for 12 weeks in a phase 1/2a study were classified as responders (n = 10) or non-responders (n = 8) based on changes in liver stiffness. Plasma samples were obtained before and after PRI-724 administration and the levels of EV-miRNAs were analyzed. Three miRNAs (miR-6510-5p, miR-6772-5p, and miR-4261) were identified as predictors of response or non-response to PRI-724, and the levels of three other miRNAs (miR-939-3p, miR-887-3p, and miR-7112-5p) correlated with the efficacy of treatment. Expression of miR-887-3p was detected in hepatocytes and was decreased significantly in liver tissue following PRI-724 treatment. In addition, transfection of a miR-887-3p mimic activated hepatic stellate cells. Thus, decreases in the miR-887-3p level in blood may reflect recovery from liver fibroses in patients with liver cirrhosis treated with PRI-724, although further validation studies are warranted to confirm this.

Characterization of circulating miRNAs in the treatment of primary liver tumors

BACKGROUND AND AIM

Circulating micro RNAs (miRNAs) indicate clinical pathologies such as inflammation and carcinogenesis. In this study, we aimed to investigate whether miRNA expression level patterns in could be used to diagnose hepatocellular carcinoma (HCC) and biliary tract cancer (BTC), and the relationship miRNA expression patterns and cancer etiology.

METHODS

Patients with HCC and BTC with indications for surgery were selected for the study. Total RNA was extracted from the extracellular vesicle (EV)-rich fraction of the serum and analyzed using Toray miRNA microarray. Samples were divided into two cohorts in order of collection, the first 85 HCC were analyzed using a microarray based on miRBase ver.2.0 (hereafter v20 cohort), and the second 177 HCC and 43 BTC were analyzed using a microarray based on miRBase ver.21 (hereafter v21 cohort).

RESULTS

Using miRNA expression patterns, we found that HCC and BTC could be identified with an area under curve (AUC) 0.754 (v21 cohort). Patients with anti-hepatitis C virus (HCV) treatment (SVR-HCC) and without antiviral treatment (HCV-HCC) could be distinguished by an AUC 0.811 (v20 cohort) and AUC 0.798 (v21 cohort), respectively.

CONCLUSIONS

In this study, we could diagnose primary hepatic malignant tumor using miRNA expression patterns. Moreover, the difference of miRNA expression in SVR-HCC and HCV-HCC can be important information for enclosing cases that are prone to carcinogenesis after being cured with antiviral agents, but also for uncovering the mechanism for some carcinogenic potential remains even after persistent virus infection has disappeared.

miR‑146a‑5p and miR‑191‑5p as novel diagnostic marker candidates for ovarian clear cell carcinoma

Ovarian cancer is a malignant gynecologic disease rarely diagnosed in the early stages. Among the various types of ovarian cancer, clear cell carcinoma has a poor prognosis due to its malignant potential. MicroRNAs (miRNAs/miRs) regulate gene expression in cells by suppressing the translation of target genes or by degrading the target mRNA. miRNAs are also secreted from the cells in the blood, binding to proteins or lipids and assisting in cell-cell communication. Therefore, serum miRNAs may be considered potential diagnostic biomarkers for ovarian cancer. The present study investigated and identified specific miRNAs associated with ovarian clear cell carcinoma and compared them to those in ovarian endometrioma samples and healthy controls. CA125, an ovarian tumor marker, did not differ between patients with ovarian clear cell carcinoma, endometriosis or healthy controls. Subsequently, four miRNAs (miR-146a-5p, miR-191-5p, miR-484 and miR-574-3p) were analyzed. The expression levels of miR-146a-5p and miR-191-5p were significantly increased in the serum samples from patients with ovarian clear cell carcinoma compared with those in the healthy controls, but there was no significant difference compared with in patients with endometriosis. Furthermore, the bioinformatics analysis showed that CCND2 and NOTCH2 were the candidate target genes of miR-146a-5p and miR-191-5p. In conclusion, the results of the present study demonstrated that miR-146a-5p and miR-191-5p may be useful as early and non-invasive diagnostic tools in ovarian clear cell carcinoma. These miRNAs can help in distinguishing between ovarian clear cell carcinoma and ovarian endometrioma. To the best of our knowledge, no previous studies have screened any candidates specifically for ovarian clear cell carcinoma.

Potent antitumor effects of the conditioned medium of bone marrow-derived mesenchymal stem cells via IGFBP-4

Cell transfer therapy using mesenchymal stem cells (MSCs) has pronounced therapeutic potential, but concerns remain about immune rejection, emboli formation, and promotion of tumor progression. Because the mode of action of MSCs highly relies on their paracrine effects through secretion of bioactive molecules, cell-free therapy using the conditioned medium (CM) of MSCs is an attractive option. However, the effects of MSC-CM on tumor progression have not been fully elucidated. Herein, we addressed this issue and investigated the possible underlying molecular mechanisms. The CM of MSCs derived from human bone marrow greatly inhibited the in vitro growth of several human tumor cell lines and the in vivo growth of the SCCVII murine squamous cell carcinoma cell line with reduced neovascularization. Exosomes in the MSC-CM were only partially involved in the inhibitory effects. The CM contained a variety of cytokines including insulin-like growth factor binding proteins (IGFBPs). Among them, IGFBP-4 greatly inhibited the in vitro growth of these tumors and angiogenesis, and immunodepletion of IGFBP-4 from the CM significantly reversed these effects. Of note, the CM greatly reduced the phosphorylation of AKT, ERK, IGF-1 receptor beta, and p38 MAPK in a partly IGFBP4-dependent manner, possibly through its binding to IGF-1/2 and blocking the signaling. The CM depleted of IGFBP-4 also reversed the inhibitory effects on in vivo tumor growth and neovascularization. Thus, MSC-CM has potent inhibitory effects on tumor growth and neovascularization in an IGFBP4-dependent manner, suggesting that cell-free therapy using MSC-CM could be a safer promising alternative for even cancer patients.

Acerola exosome-like nanovesicles to systemically deliver nucleic acid medicine via oral administration

Extracellular vesicles derived from mammalian cells could be useful carriers for drug delivery systems (DDSs); however, with regard to clinical application, there are several issues to be overcome. Acerola (Malpighia emarginata DC.) is a popular health food. In this study, the feasibility of orally administered nucleic acid drug delivery by acerola exosome-like nanoparticles (AELNs) was examined. AELNs were recovered from acerola juice using an affinity column instead of ultracentrifugation. MicroRNA (miRNA) was sufficiently encapsulated in AELNs by 30-min incubation on ice and was protected against RNase, strong acid, and base treatments. The administration of an AELN/miRNA mixture in cells achieved downregulation of the miRNA’s target gene, and this mixture showed cytoplasmic localization. AELNs orally delivered small RNA to the digestive system in vivo. The target gene-suppressing effect in the small intestine and liver peaked 1 day after administration, indicating potential for use as an oral DDS for nucleic acid in the digestive system.

Comprehensive analysis of liver and blood miRNA in precancerous conditions

Streptozotocin administration to mice (STZ-mice) induces type I diabetes and hepatocellular carcinoma (HCC). We attempted to elucidate the carcinogenic mechanism and the miRNA expression status in the liver and blood during the precancerous state. Serum and liver tissues were collected from STZ-mice and non-treated mice (CTL-mice) at 6, 10, and 12 W. The exosome enriched fraction extracted from serum was used. Hepatic histological examination and hepatic and exosomal miRNA expression analysis were serially performed using next-generation sequencing (NGS). Human miRNA expression analysis of chronic hepatitis liver tissue and exosomes, which were collected before starting the antiviral treatment, were also performed. No inflammation or fibrosis was found in the liver of CTL-mice during the observation period. In STZ-mice, regeneration and inflammation of hepatocytes was found at 6 W and nodules of atypical hepatocytes were found at 10 and 12 W. In the liver tissue, during 6-12 W, the expression levels of let-7f-5p, miR-143-3p, 148a-3p, 191-5p, 192-5p, 21a-5p, 22-3p, 26a-5p, and 92a-3p was significantly increased in STZ-mice, and anti-oncogenes of their target gene candidates were down-regulated. miR-122-5p was also significantly down-regulated in STZ-mice. Fifteen exosomal miRNAs were upregulated in STZ-mice. Six miRNAs (let-7f-5p, miR-10b-5p, 143-3p, 191-5p, 21a-5p, and 26a-5p) were upregulated, similarly to human HCC cases. From the precancerous state, aberrant expression of hepatic miRNAs has already occurred, and then, it can promote carcinogenesis. In exosomes, the expression pattern of common miRNAs between mice and humans before carcinogenesis was observed and can be expected to be developed as a cancer predictive marker.

Comprehensive Gene Analysis of IgG4-Related Ophthalmic Disease Using RNA Sequencing

High-throughput RNA sequencing (RNA-seq) uses massive parallel sequencing technology, allowing the unbiased analysis of genome-wide transcription levels and tumor mutation status. Immunoglobulin G4-related ophthalmic disease (IgG4-ROD) is a fibroinflammatory disease characterized by the enlargement of the ocular adnexal tissues. We analyzed RNA expression levels via RNA-seq in the biopsy specimens of three patients diagnosed with IgG4-ROD. Mucosa-associated lymphoid tissue (MALT) lymphoma, reactive lymphoid hyperplasia (RLH), normal lacrimal gland tissue, and adjacent adipose tissue were used as the controls (n = 3 each). RNA-seq was performed using the NextSeq 500 system, and genes with |fold change| ≥ 2 and p < 0.05 relative to the controls were defined as differentially expressed genes (DEGs) in IgG4-ROD. To validate the results of RNA-seq, real-time polymerase chain reaction (PCR) was performed in 30 IgG4-ROD and 30 orbital MALT lymphoma tissue samples. RNA-seq identified 35 up-regulated genes, including matrix metallopeptidase 12 (MMP12) and secreted phosphoprotein 1 (SPP1), in IgG4-ROD tissues when compared to all the controls. Many pathways related to the immune system were included when compared to all the controls. Expressions of MMP12 and SPP1 in IgG4-ROD tissues were confirmed by real-time PCR and immunohistochemistry. In conclusion, we identified novel DEGs, including those associated with extracellular matrix degradation, fibrosis, and inflammation, in IgG4-ROD biopsy specimens. These data provide new insights into molecular pathogenetic mechanisms and may contribute to the development of new biomarkers for diagnosis and molecular targeted drugs.

Effect of the extracellular component of bone marrow mesenchymal stromal cells from healthy donors on hematologic neoplasms and their angiogenesis

Bone marrow mesenchymal stromal cells (BM-MSCs) from healthy donors are a promising source of cell therapy. However, their effectiveness in cancer remains less known. This study is the first to evaluate the quality of BM-MSCs obtained from young and elderly healthy volunteers (KNT cells). The KNT cells had normal karyotypes and were positive for MSC markers (CD90, CD73, CD105). When cultured under appropriate conditions, they showed adipogenic or osteogenic potential. Hence, the anti-neoplastic effects of secretory factors [supernatant or extracellular vesicles (EV)] from KNT cells were verified using several neoplastic cells (three multiple myeloma, three myeloid leukemia, and three lymphoma cell lines). The conditioned medium (CM), but not EV, of KNT cells derived from young healthy donors significantly inhibited myeloma and lymphoma cell proliferation, but enhanced myeloid leukemia proliferation. Anti-angiogenesis effect of CM and EV derived from young KNT against hematologic neoplasia-induced angiogenesis was evident and more prominent in CM than in EV but not evident in elderly KNT-derived EV. These findings indicate that the anti-tumor effect of KNT cells depends on the types of hematologic neoplasia, with elements existing in the supernatant and not in EVs. Therefore, BM-MSC may produce soluble factors that affect cell proliferation of neoplasia, causing cell-to-cell communication. The anti-angiogenesis effect of KNT cells depends on the age of BM-MSC donors.

Downregulation of extracellular vesicle microRNA-101 derived from bone marrow mesenchymal stromal cells in myelodysplastic syndrome with disease progression

To evaluate the mechanism underlying the communication between myeloid malignant and bone marrow (BM) microenvironment cells in disease progression, the current study established BM mesenchymal stromal cells (MSCs) and assessed extracellular vesicle (EV) microRNA (miR) expression in 22 patients with myelodysplastic syndrome (MDS) and 7 patients with acute myeloid leukemia and myelodysplasia-related changes (AML/MRC). Patients with MDS were separated into two categories based on the revised International Prognostic Scoring System (IPSS-R), and EV-miR expression in BM-MSCs was evaluated using a TaqMan low-density array. The selected miRs were evaluated using reverse transcription-quantitative PCR. The current study demonstrated that the expression of BM-MSC-derived EV-miR was heterogenous and based on MDS severity, the expression of EV-miR-101 was lower in high-risk group and patients with AML/MRC compared with the control and low-risk groups. This reversibly correlated with BM blast percentage, with which the cellular miR-101 from BM-MSCs or serum EV-miR-101 expression exhibited no association. Database analyses indicated that miR-101 negatively regulated cell proliferation and epigenetic gene expression. The downregulation of BM-MSC-derived EV-miR-101 may be associated with cell-to-cell communication and may accelerate the malignant process in MDS cells.

A novel non-invasive monitoring assay of 5-azacitidine efficacy using global DNA methylation of peripheral blood in myelodysplastic syndrome

Purpose: Monitoring response and resistance to 5-azacitidine (AZA) is essential when treating patients with myelodysplastic syndrome (MDS). To quantify methylated DNA not only in the promoter region but also in the gene body, we established a single-molecule methylation assay (SMMA).

Patients and methods: We first investigated the methylation extent (expressed as methylation index [MI]) by SMMA among 28 MDS and 6 post-MDS acute myeloid leukemia patients. We then analyzed the MI in 13 AZA-treated patients.

Results: Whole-blood DNA from all 34 patients had low MI values compared with healthy volunteers (P<0.0001). DNA hypomethylation in MDS patients was more evident in neutrophils (P=0.0008) than in peripheral mononuclear cells (P=0.0713). No consistent pattern of genome-wide DNA hypomethylation was found among MDS subtypes or revised International Prognostic Scoring System (IPSS-R) categories; however, we found that the MI was significantly increased for patients at very high risk who were separated by the new cytogenetic scoring system for IPSS-R (P=0.0398). There was no significant difference in MI before AZA, regardless of the response to AZA (P=0.8689); however, sequential measurement of MI in peripheral blood demonstrated that AZA non-responders did not have normalized MI at the time of next course of AZA (P=0.0352).

Conclusion: Our results suggest that sequential SMMA of peripheral blood after AZA may represent a non-invasive monitoring marker for AZA efficacy in MDS patients.

Lineage-specific RUNX2 super-enhancer activates MYC and promotes the development of blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive subtype of acute leukemia, the cell of origin of which is considered to be precursors of plasmacytoid dendritic cells (pDCs). Since translocation (6;8)(p21;q24) is a recurrent anomaly for BPDCN, we demonstrate that a pDC-specific super-enhancer of RUNX2 is associated with the MYC promoter due to t(6;8). RUNX2 ensures the expression of pDC-signature genes in leukemic cells, but also confers survival and proliferative properties in BPDCN cells. Furthermore, the pDC-specific RUNX2 super-enhancer is hijacked to activate MYC in addition to RUNX2 expression, thereby promoting the proliferation of BPDCN. We also demonstrate that the transduction of MYC and RUNX2 is sufficient to initiate the transformation of BPDCN in mice lacking Tet2 and Tp53, providing a model that accurately recapitulates the aggressive human disease and gives an insight into the molecular mechanisms underlying the pathogenesis of BPDCN.

Chromatin Regulation by HP1γ Contributes to Survival of 5-Azacytidine-Resistant Cells

Recent investigations of the treatment for hematologic neoplasms have focused on targeting epigenetic regulators. The DNA methyltransferase inhibitor 5-azacytidine (AZA) has produced good results in the treatment of patients with myelodysplastic syndromes. The mechanism underlying its pharmacological activity involves many cellular processes including histone modifications, but chromatin regulation in AZA-resistant cells is still largely unknown. Therefore, we compared human leukemia cells with AZA resistance and their AZA-sensitive counterparts with regard to the response of histone modifications and their readers to AZA treatment to identify novel molecular target(s) in hematologic neoplasms with AZA resistance. We observed an a decrease of HP1γ, a methylated lysine 9 of histone H3-specific reader protein, in AZA-sensitive cells after treatment, whereas AZA treatment did not affect HP1 family proteins in AZA-resistant cells. The expression of shRNA targeting HP1γ reduced viability and induced apoptosis specifically in AZA-resistant cells, which accompanied with down-regulation of ATM/BRCA1 signaling, indicating that chromatin regulation by HP1γ plays a key role in the survival of AZA-resistant cells. In addition, the amount of HP1γ protein in AZA-sensitive and AZA-resistant cells was decreased after treatment with the bromodomain inhibitor I-BET151 at a dose that inhibited the growth of AZA-resistant cells more strongly than that of AZA-sensitive cells. Our findings demonstrate that treatment with AZA, which affects an epigenetic reader protein and targets HP1γ, or a bromodomain inhibitor is a novel strategy that can be used to treat patients with hematopoietic neoplasms with AZA resistance.

Stratification of mouse vaginal epithelium. 1. Development of three-dimensional models in vitro with clonal cell lines

The mouse vagina consists of stratified squamous epithelium and stroma and is regulated by ovarian hormones. Vaginal epithelial cells do not stratify, but rather form a monolayer and show an inconsistent responsiveness to ovarian hormones when cultured on plastic dish or matrix. To address the discrepancy between in vivo and in vitro observations, three-dimensional (3D) co-culture models are developed with clonal vaginal epithelial and stromal cell lines; stromal cells are embedded in collagen gel and epithelial cells are seeded on the gel. In the 3D models, epithelial cells express Transformation related protein 63 (Trp63) and begin to stratify when they are co-cultured with two out of three stromal cell lines, but not with the other stromal cell line. Stroma may consist of various types of cells with distinct functions.

Exosomal miRNA Signatures for Late-Onset Acute Graft-Versus-Host Disease in Allogenic Hematopoietic Stem Cell Transplantation

Recent studies have demonstrated that exosomal microRNAs (miRNAs) have the potential of facilitating molecular diagnosis. Currently, little is known about the underlying mechanism behind late-onset acute graft-versus-host disease (LA GVHD). Identifying differentially expressed miRNAs in exosomes should be useful for understanding the role of miRNAs in this disease. This study was established to investigate the relevance of miRNAs in exosomes derived from patients developing LA GVHD after allogeneic hematopoietic stem cell transplantation (HSCT). Plasma samples were collected from patients with LA GVHD (n = 5), non-GVHD (n = 5), and controls (n = 8) for exosomal miRNA expression profiling using a TaqMan low-density array; the results were validated by quantitative reverse transcription polymerase chain reaction (RT-PCR). We analyzed exosomal miRNAs differentially expressed among these three groups. MirTarBase was employed to predict potential target genes of the miRNAs specific for LA GVHD. We detected 55 miRNAs that were differentially expressed with a significant change >2.0-fold between LA GVHD and non-GVHD. Of these, we selected the 10 miRNAs (miR-423-5p, miR-19a, miR-142-3p, miR-128, miR-193b, miR-30c, miR-193a, miR-191, miR-125b, and miR-574-3p) with the most significant differential expression. Using quantitative RT-PCR, we further identified that miR-128 was significantly upregulated at the onset of LA GVHD compared with that in normal controls and is a promising diagnostic marker of LA GVHD, with an area under the curve (AUC) value of 0.975. MirTarBase analysis revealed that the predicted target genes of miR-128 are involved in the immune system and inflammation. Increased expression of miR-128 may serve as a novel, noninvasive biomarker for early LA GVHD diagnosis.

Extracellular vesicle-mediated cell-cell communication in haematological neoplasms

Crosstalk between bone marrow tumour cells and surrounding cells, including bone marrow mesenchymal stromal cells (BM-MSCs), endothelial cells and immune cells, is important for tumour growth in haematological neoplasms. In addition to conventional signalling pathways, extracellular vesicles (EVs), which are endosome-derived vesicles containing proteins, mRNAs, lipids and miRNAs, can facilitate modulation of the bone marrow microenvironment without directly contacting non-tumourous cells. In this review, we discuss the current understanding of EV-mediated cell-cell communication in haematological neoplasms, particularly leukaemia and multiple myeloma. We highlight the actions of tumour and BM-MSC EVs in multiple myeloma. The origin of EVs, their tropism and mechanism of EV transfer are emerging issues that need to be addressed in EV-mediated cell-cell communication in haematological neoplasms.This article is part of the discussion meeting issue 'Extracellular vesicles and the tumour microenvironment'.

Genetic variations of bone marrow mesenchymal stromal cells derived from acute leukemia and myelodysplastic syndrome by targeted deep sequencing

Bone marrow mesenchymal stromal cells (MSCs), which support proliferation and differentiation of hematopoietic stem cells, may play a crucial role in the pathogenesis of myeloid neoplasms. To determine whether MSCs in myeloid neoplasms harbor distinct somatic mutations that may affect their function, we used a targeted gene sequencing panel containing 50 myeloid neoplasm-associated genes with coverage of ≥500. We compared the genetic alterations between MSCs and bone marrow hematopoietic (BM) cells from patients with acute leukemia (n=5) or myelodysplastic syndrome (MDS, n=5). Non-synonymous somatic mutations, such as DNMT3A-R882H and FLT3-D835Y, were only detected in BM cells with high allelic frequency. We found several non-synonymous genetic variants overlapping BM cells and MSCs, including TP53 and ASXL1, partially owing to the heterogenous cell fraction of MSC samples and lineage fidelity. We also found MSC-specific genetic variants with very low allelic frequency (7% to 8%), such as NF1-G2114D and NF1-G140. Further studies in large cohorts are needed to clarify the molecular properties of MSCs including age-related genetic alterations by targeted deep sequencing.

Teriflunomide restores 5-azacytidine sensitivity via activation of pyrimidine salvage in 5-azacytidine-resistant leukemia cells

Previous studies showed that downregulation of pyrimidine salvage underlies resistance against 5-azacytidine (AZA), indicating an important role for de novo pyrimidine synthesis in AZA resistance. Because de novo pyrimidine synthesis is inhibited by the immunomodulator teriflunomide and its pro-drug leflunomide, we examined the effect of combined treatment with AZA and teriflunomide on AZA resistance to develop a novel strategy to cancel and prevent AZA resistance. Teriflunomide markedly inhibited the growth of AZA-resistant human leukemia cell lines (R-U937 and R-HL-60) in comparison with their AZA-sensitive counterparts (U937 and HL-60). In the presence of a non-toxic concentration of teriflunomide (1 μM), AZA induced apoptosis in AZA-resistant cells and leukemia cells from AZA-resistant patients. AZA acted as a DNA methyltransferase 3A inhibitor in AZA-resistant cells in the presence of 1 μM teriflunomide. Although AZA-sensitive cells acquired AZA resistance after continuous treatment with AZA for 42 days, the growth of AZA-sensitive cells continuously treated with the combination of AZA and teriflunomide was significantly inhibited in the presence of AZA, demonstrating that the combined treatment prevented AZA resistance. These results suggest that combined treatment with AZA and teriflunomide can be a novel strategy to overcome AZA resistance.

Up-regulated exosomal miRNA-140-3p in CML patients with musculoskeletal pain associated with discontinuation of tyrosine kinase inhibitors

We analyzed the exosomal miRNA from peripheral blood from CML patients with musculoskeletal pain after stopping tyrosine kinase inhibitors to identify possible factors related to this manifestation. Exosomal miRNA profiling using TaqMan low-density array revealed that exosomal miR-140-3p was significantly elevated in CML patients showing musculoskeletal pain, when compared to those without such pain (P = 0.0336) or healthy individuals (P = 0.0022). All five CML patients with musculoskeletal pain and increased exosomal miR-140-3p levels sustained deep molecular responses: four of them achieved symptom relief and a significant decrease in exosomal miR-140-3p levels was evident. Because exosomal miR-140-3p is considered to have an inflammation-associated biological function in airway smooth muscle cells and targets Myomarker muscle-specific transmembrane protein, it appears that its overexpression in circulating exosomal miR-140-3p may have some role in the mechanism underlying self-limited musculoskeletal pain.

Downregulation of Plasma miR-215 in Chronic Myeloid Leukemia Patients with Successful Discontinuation of Imatinib

Approximately 40% of chronic myeloid leukemia (CML) patients who discontinue imatinib (IM) therapy maintain undetectable minimal residual disease (UMRD) for more than one year (stopping IM (STOP-IM)). To determine a possible biomarker for STOP-IM CML, we examined plasma miRNA expression in CML patients who were able to discontinue IM. We first screened candidate miRNAs in unselected STOP-IM patients, who had sustained UMRD after discontinuing IM for more than six months, in comparison with healthy volunteers, by using a TaqMan low-density array for plasma or exosomes. Exosomal miR-215 and plasma miR-215 were downregulated in the STOP-IM group compared to the control, indicating that the biological relevance of the plasma miR-215 level is equivalent to that of the exosomal level. Next, we performed real-time quantitative RT-PCR in 20 STOP-IM patients, 32 patients with UMRD on continued IM therapy (IM group) and 28 healthy volunteers. The plasma miRNA-215 level was significantly downregulated in the STOP-IM group (p < 0.0001); we determined the cut-off level and divided the IM group patients into two groups according to whether the plasma miR-215 was downregulated or not. The IM group patients with a low plasma miR-215 level had a significantly higher total IM intake, compared to the patients with elevated miR-215 levels (p = 0.0229). Functional annotation of miR-215 target genes estimated by the Database for Annotation, Visualization and Integrated Discovery (DAVID) bioinformatic tools involved cell cycle, mitosis, DNA repair and cell cycle checkpoint. Our study suggests a possible role of miR-215 in successful IM discontinuation.

[Treatment-free molecular remission achieved by combination therapy with imatinib and IFNα in CML with BIM deletion polymorphism relapsed after stop imatinib]

A 51-year-old man with chronic myeloid leukemia (CML) was treated with imatinib (IM). After 24 months of treatment, he achieved a complete molecular response (CMR), which he sustained for 3 years. However, 4 months after discontinuing IM treatment, the CML relapsed. The patient was treated again with IM and achieved CMR. A combination of IM and interferon-α (IFNα) was administered for the following year, and then discontinued. The patient has since sustained CMR without therapy for 24 months, to date. This patient was found to have a BCL2L11 (BIM) deletion polymorphism. CML patients with a BIM deletion polymorphism show a low response to IM, and we infer that the BIM deletion polymorphism is a negative factor for discontinuation of IM. IFNα treatment is expected to prevent relapse during immunological surveillance. Therefore, the combination of IM and IFNα might be a feasible approach for CML patients who experience difficulty with IM discontinuation.

Downregulated microRNA-148b in circulating PBMCs in chronic myeloid leukemia patients with undetectable minimal residual disease: a possible biomarker to discontinue imatinib safely

BACKGROUND

A subset of patients with chronic myeloid leukemia (CML) can sustain a complete molecular response after discontinuing imatinib mesylate (IM). We focused on microRNAs (miRNAs), with the aim of finding a molecular biomarker to discriminate which patients can safely and successfully discontinue IM use.

METHODS

To identify miRNAs that showed altered expression in patients who had discontinued IM (STOP-IM group), we first screened miRNA expression of peripheral blood mononuclear cells by using a TaqMan miRNA array on samples from five unselected patients from the STOP-IM group, seven CML patients receiving IM (IM group), and five healthy volunteers. We then performed miRNA quantification in 49 CML patients with deep molecular response. Mann-Whitney U and chi-square tests were used to determine statistical significance for comparisons between the control (healthy volunteers) and test groups (STOP-IM and IM groups). Multiple groups were compared by one-way analysis of variance.

RESULTS

Downregulation of miR-148b was noted in patients in the STOP-IM group and in a subset of the IM group. We then subdivided the IM patients into two groups: one with downregulated miR-148b expression (IM-1; less than the cut-off value) and the other without downregulated miR-148b expression (IM-2; greater than the cut-off value). The number of patients who had a sustained stable molecular response was significantly lower in IM-2 group. This group also had a significantly lower percentage of natural killer cells.

CONCLUSION

Downregulated miR-148 may contribute to immune surveillance in STOP-IM patients and may therefore have potential as additive information in managing CML patients undergoing treatment with IM.

Exosomes derived from hypoxic leukemia cells enhance tube formation in endothelial cells

Hypoxia plays an important role during the evolution of cancer cells and their microenvironment. Emerging evidence suggests communication between cancer cells and their microenvironment occurs via exosomes. This study aimed to clarify whether hypoxia affects angiogenic function through exosomes secreted from leukemia cells. We used the human leukemia cell line K562 for exosome-generating cells and human umbilical vein endothelial cells (HUVECs) for exosome target cells. Exosomes derived from K562 cells cultured under normoxic (20%) or hypoxic (1%) conditions for 24 h were isolated and quantitated by nanoparticle tracking analysis. These exosomes were then cocultured with HUVECs to evaluate angiogenic activity. The exosomes secreted from K562 cells in hypoxic conditions significantly enhanced tube formation by HUVECs compared with exosomes produced in normoxic conditions. Using a TaqMan low-density miRNA array, we found a subset of miRNAs, including miR-210, were significantly increased in exosomes secreted from hypoxic K562 cells. We demonstrated that cancer cells and their exosomes have altered miRNA profiles under hypoxic conditions. Although exosomes contain various molecular constituents such as proteins and mRNAs, altered exosomal compartments under hypoxic conditions, including miR-210, affected the behavior of endothelial cells. Our results suggest that exosomal miRNA derived from cancer cells under hypoxic conditions may partly affect angiogenic activity in endothelial cells.

Abstract 5627: Involvement of pyrimidine metabolism pathway in 5-azacytidine resistance

Background and aim

5-azacytidine (AZA) is a DNA demethylating agent that is clinically used for patients with myelodysplastic syndrome and acute myeloid leukemia. However, the mechanism of AZA-resistance remains unclear although many patients become resistant to AZA after short-term use. To investigate the mechanism of AZA resistance, we established an AZA-resistant cell line and analyzed its cellular and molecular biological characteristics.

Experimental procedures

To establish the AZA-resistant cell line, U937 cells were incubated in a gradually increasing dose of AZA from 0.1 μM to 3 μM. Surviving cells were named R-U937. The profiles of mRNA expression and DNA methylation in U937 and R-U937 cells were obtained and pathway analysis was performed to determine differences between U937 and R-U937. Experiments using specific inhibitors were also performed.

Results

Proliferation and drug resistance of R-U937

R-U937 cells showed a lower proliferation rate than their parent cells, but their viability was not affected by AZA or 2’-deoxy-AZA (DAC).

Role of pyrimidine metabolism pathway in AZA resistance

The pathway analysis of mRNA expression profiles revealed differences between U937 and R-U937 in terms of the mRNA expression level of 4 genes involved in the ‘Pyrimidine Metabolism Pathway’. The observation was confirmed by quantitative RT-PCR. R-U937 cells re-acquired sensitivity to AZA when they were incubated with an inhibitor of CTP synthase. These results indicated that adaptation in pyrimidine metabolism, particularly the accelerated synthesis of CTP from UTP, played important roles in the development of an AZA-resistant phenotype.

Role of DNA hypomethylation in AZA resistance

The DNA demethylation process induced by AZA involves inhibition of DNA methyltransferases (DNMTs) and DNA damage. It is not clear which process is the major mechanism of the anti-leukemia activity. To clarify this, we compared the effects of AZA, DAC and RG108, a DNMT inhibitor with no DNA damaging activity, on viability and DNA damage. AZA and DAC significantly decreased U937 cell viability, but not RG108. U937 incubated with AZA or DAC showed an increased ratio of p-H2AX-positive cells, indicating that these agents caused DNA damage. However, the ratio of p-H2AX-positive cells in U937 incubated with RG108 was equal to that of cells incubated without the agents. In R-U937, all agents did not increase the ratio of p-H2AX-positive cells. The DNA methylation profiles revealed global hypomethylation in R-U937. These results indicated that DNA damage but not DNMT inhibition played a major role in the anti-leukemia activity of AZA and DAC.

Conclusion

The present results showed that the development of an AZA-resistant phenotype of R-U937 depended on the adaptation in pyrimidine metabolism and global DNA hypomethylation. To overcome AZA resistance, pyrimidine metabolism, particularly CTP synthase, can be a good target.

Citation Format: Satoshi Imanishi, Tomohiro Umezu, Chiaki Kobayashi, Kazuma Ohyashiki, Junko Ohyashiki. Involvement of pyrimidine metabolism pathway in 5-azacytidine resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5627. doi:10.1158/1538-7445.AM2013-5627

Abstract 2305: Hypoxia modulates tumor exosomes, which function as mediators of angiogenesis

Background and aim. We have recently shown tumor cell to endothelial cell communication and the induction of endothelial cell migration via exosomes (Umezu et al., Oncogene 2012). The aim of this study was to clarify whether hypoxia promotes angiogenic activity through tumor exosomes.

Experimental procedures. We used the human leukemia cell line K562 as exosome-generating cells and human umbilical vein endothelial cells (HUVECs) as exosome target cells. Exosomes derived from K562 cells cultured under normoxic (20%) or hypoxic (1%) condition for 24h were isolated using Exoquick (System Bioscience) and quantitated by nano-particle analysis as well as immunoblotting for the exosomal protein CD63. These exosomes were added to HUVECs cultured on Matrigel for the validation of angiogenic activity, such as tube formation assay. Cellular and exosomal miRNAs responding to hypoxia were analyzed using TaqMan low-density miRNA array (TLDA, Applied Biosystems).

Results. The exosomes derived from K562 cells cultured under hypoxic condition enhanced tube formation of HUVECs. Culture under hypoxic condition for 24h affected neither the tumor cell growth nor the amount of exosome secreted into the culture medium, while culture under the same condition induced the up-regulation of HIF-1α expression. The exosomes derived from K562 cells cultured under hypoxic condition for 24h (K562-1%O2-exosomes) markedly enhanced the tube formation of HUVECs compared with the exosomes obtained from K562 cells cultured under normoxic condition (K562-20%O2-exosomes), indicating that K562-1%O2-exosomes potentially included angiogenic factors. Cellular and exosomal miRNA profiling of K562 cells cultured under hypoxic condition. Using TLDA, we profiled the expression of cellular and exosomal miRNAs and observed a fold change of &gt;1.5 under hypoxic condition compared with normoxic condition. We found that a subset of miRNAs, including miR-210, was significantly elevated under hypoxic condition in both cells and exosomes. The exosomal miRNAs derived from K562 cells cultured under hypoxic condition reduced the expression of Ephrin-A3 in HUVECs. We next examined the expression of Ephrin-A3 (EFNA3), an antiangiogenic factor, since miR-210 targets EFNA3. We demonstrated that EFNA3 expression was inhibited when HUVECs were exposed to hypoxic condition for 24h. Similarly, EFNA3 expression was drastically reduced by the addition of K562-1%O2-exosomes into HUVECs.

Conclusions. We demonstrated that tumor cells and their exosomes have altered miRNA profiles under hypoxic condition. Although exosomes contain various molecular constituents, such as proteins and mRNAs, altered exosomal compartments under hypoxic condition, including miR-210, affect antiangiogenic factors. Our results suggest the possibility that exosomal miRNA derived from tumor cells cultured under hypoxic condition may partly affect angiogenic activity in endothelial cells.

Citation Format: Tomohiro Umezu, Hiroko Tadokoro, Kazuma Ohyashiki, Junko H. Ohyashiki. Hypoxia modulates tumor exosomes, which function as mediators of angiogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2305. doi:10.1158/1538-7445.AM2013-2305

Clinical relevance of plasma miR-106b levels in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by both chronic inflammation in the airway and systemic inflammation; however, the molecular mechanism of COPD has not been fully elucidated. By measuring microRNA (miRNA) expression in the plasma of COPD subjects, we aimed to identify the clinical relevance of plasma miRNA levels in these patients. Blood samples were obtained from COPD patients and age-matched normal controls. We initially produced plasma miRNA expression profiles using TaqMan low-density array screening. For further validation, individual qRT-PCRs were performed in 40 COPD patients and 20 healthy subjects. TaqMan low-density array screening showed that 9 miRNAs (miR-29b, miR-483-5p, miR-152, miR-629, miR-26b, miR-101, miR-106b, miR-532-5p and miR-133b) were significantly downregulated in the plasma from COPD patients when compared with normal smokers. Among these miRNAs, we focused on miR-106b. A reduction in the plasma miR-106b levels was evident in COPD ex-smokers and COPD current smokers compared with levels in smokers. There was a negative correlation between the plasma miR-106b level and the duration of disease since diagnosis in COPD ex-smokers and the duration of smoking in COPD current smokers. These findings support the concept that progressive reduction in the plasma miR-106b level may reflect persistent and systemic changes even after the discontinuation of smoking in COPD patients. miR-106b may therefore play an important role in the pathogenesis of COPD.

High expression of N-acetylglucosaminyltransferase IVa promotes invasion of choriocarcinoma

Background:

Gestational trophoblastic diseases (GTDs) are related to trophoblasts, and human chorionic gonadotropin (hCG) is secreted by GTDs as well as normal placentas. However, the asparagine-linked sugar chains on hCG contain abnormal biantennary structures in invasive mole and choriocarcinoma, but not normal pregnancy or hydatidiform mole. N-acetylglucosaminyltransferase-IV (GnT-IV) catalyses β1,4-N-acetylglucosamine branching on asparagine-linked oligosaccharides, which are consistent with the abnormal sugar chain structures on hCG.

Methods:

We investigated GnT-IVa expression in GTDs and placentas by immunohistochemistry, western blot, and RT–PCR. We assessed the effects of GnT-IVa knockdown in choriocarcinoma cells in vitro and in vivo.

Results:

The GnT-IVa was highly expressed in trophoblasts of invasive mole and choriocarcinoma, and moderately in extravillous trophoblasts during the first trimester, but not in hydatidiform mole or other normal trophoblasts. The GnT-IVa knockdown in choriocarcinoma cells significantly reduced migration and invasive capacities, and suppressed cellular adhesion to extracellular matrix proteins. The extent of β1,4-N-acetylglucosamine branching on β1 integrin was greatly reduced by GnT-IVa knockdown, although the expression of β1 integrin was not changed. In vivo studies further demonstrated that GnT-IVa knockdown suppressed tumour engraftment and growth.

Conclusion:

These findings suggest that GnT-IVa is involved in regulating invasion of choriocarcinoma through modifications of the oligosaccharide chains of β1 integrin.

The C allele of JAK2 rs4495487 is an additional candidate locus that contributes to myeloproliferative neoplasm predisposition in the Japanese population

Background

Polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are myeloproliferative neoplasms (MPNs) characterized in most cases by a unique somatic mutation, JAK2 V617F. Recent studies revealed that JAK2 V617F occurs more frequently in a specific JAK2 haplotype, named JAK2 46/1 or GGCC haplotype, which is tagged by rs10974944 (C/G) and/or rs12343867 (T/C). This study examined the impact of single nucleotide polymorphisms (SNPs) of the JAK2 locus on MPNs in a Japanese population.

Methods

We sequenced 24 JAK2 SNPs in Japanese patients with PV. We then genotyped 138 MPN patients (33 PV, 96 ET, and 9 PMF) with known JAK2 mutational status and 107 controls for a novel SNP, in addition to two SNPs known to be part of the 46/1 haplotype (rs10974944 and rs12343867). Associations with risk of MPN were estimated by odds ratios and their 95% confidence intervals using logistic regression.

Results

A novel locus, rs4495487 (T/C), with a mutated T allele was significantly associated with PV. Similar to rs10974944 and rs12343867, rs4495487 in the JAK2 locus is significantly associated with JAK2-positive MPN. Based on the results of SNP analysis of the three JAK2 locus, we defined the "GCC genotype" as having at least one minor allele in each SNP (G allele in rs10974944, C allele in rs4495487, and C allele in rs12343867). The GCC genotype was associated with increased risk of both JAK2 V617F-positive and JAK2 V617F-negative MPN. In ET patients, leukocyte count and hemoglobin were significantly associated with JAK2 V617F, rather than the GCC genotype. In contrast, none of the JAK2 V617F-negative ET patients without the GCC genotype had thrombosis, and splenomegaly was frequently seen in this subset of ET patients. PV patients without the GCC genotype were significantly associated with high platelet count.

Conclusions

Our results indicate that the C allele of JAK2 rs4495487, in addition to the 46/1 haplotype, contributes significantly to the occurrence of JAK2 V617F-positive and JAK2 V617F-negative MPNs in the Japanese population. Because lack of the GCC genotype represents a distinct clinical-hematological subset of MPN, analyzing JAK2 SNPs and quantifying JAK2 V617F mutations will provide further insights into the molecular pathogenesis of MPN.

Abstract PR12: Extracellular miR-92a secreted by human leukemia cells enhances endothelial cell migration in HUVECs

Background and Aim: The miR-17-92 cluster has a potent tumor angiogenesis-regulating activity, and it appears to act as a cluster in which the individual miRNAs show intricate activity. Recently, the existence of extracellular miRNAs enclosed in exosomes has raised the possibility that they play an important role in cell-cell interaction. To elucidate whether or not extracellular miRNAs derived from neoplastic cells transfer into endothelial cells and become functionally active in the recipient cells, we investigated the interaction of a leukemia cell line (K562 cells) and human umbilical vein endothelial cells (HUVECs), because K562 cells release the miR-17-92 cluster, particularly miR-92a, into the extracellular environment.

Experimental Procedures: K562 cells and HUVECs were cocultured separately using a Transwell filter (0.4-μm pore, Corning). After coculture for 24 h, the culture medium was collected and extracellular miRNAs were isolated using the mirVana PARIS kit (Ambion). The Pre-miR miRNA precursor (hsa-miR-92a; Ambion) was labeled using the Label IT siRNA Tracker Cy3 kit (Mirus), and K562 cells were transfected with 10 nM of the Cy3-labeled PremiR miRNA precursor. The day following transfection, cells were washed three times with PBS, and the culture medium was replaced with fresh serum-free AIM V medium (Invitrogen). After incubation for 24 h, the culture medium was collected, and the exosomal fraction was isolated using Exoquick (System Biosciences).

Results: Transfer of extracellular miR-92a from the donor cells to the endothelial cells. K562 cells transfected with Cy3-labeled Pre-mir-92a were noncontact cocultured with HUVECs. Twenty-four hours after coculture, Cy3-miR-92a signals were detected in the cytoplasm of HUVECs. Moreover, Cy3-miR-92a colocalized with the signals of CD63, an exosomal marker.

Exosomal miR-92a directly regulates the target gene. We performed a luciferase reporter assay and examined the expression of integrin α5, a target gene for miR-92a. Luciferase activity was markedly reduced and a significant suppression of integrin α5 expression by extracellular miR-92a was observed in HUVECs. This indicates that exogenous miRNA via exosomal transport can function equally as endogenous miRNA in HUVECs.

Exosomal miR-92a enhances endothelial cell migration in HUVECs. We found that HUVECs incorporating exosomal miRNA showed active movement. In addition, wound-healing assay revealed that there were more Cy3-labeled miR-92a signals in migrating HUVECs, but the incorporation of extracellular miR-92a to HUVECs was inhibited by cytochalasin D, a migration inhibitor. This indicates that the incorporation of exosomal miRNA may be closely linked to the movement of HUVECs. Notably, cell migration assay using an 8-μm pore Transwell revealed that an excess of extracellular miR-92a strongly enhanced endothelial cell migration.

Conclusions: Our study showed that extracellular miRNAs originating from neoplastic cells are incorporated into endothelial cells via exosomal transport and exert tumor-angiogenic function in endothelial cells. HUVEC migration enhanced the uptake of extracellular miR-92a, and an excess of extracellular miR-92a enhanced HUVEC migration. Our results provide a new insight into the angiogenic function of miR-92a, and revealed that extracellular miRNAs play an important role in neoplasia-to-endothelial cell communication.

This abstract is also presented as Poster C25.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr PR12.

Abstract C19: DNA demethylation induces upregulation of telomere repeat-containing RNA (TERRA) and downregulation of telomerase activity in human leukemia cells

Background and aim: Telomere elongation mechanisms have been proposed to be regulated by the epigenetic status of the telomeric chromatin. Telomere repeat-containing RNAs (TERRAs), which are RNAs that originate from telomeric DNA transcription, can associate with the telomeric chromatin, where they are proposed to function as negative regulators of telomere length based on their ability to act as potent inhibitors of telomerase in vitro. To elucidate the regulatory mechanism of telomere length in a chromatin-dependent manner, we analyzed factors that influence telomere/telomerase regulation in human leukemia cells treated with 5-azacytidine, a currently available demethylating agent.

Methods: Reagents and cells: Human leukemia cell lines (U937, K562, and HL-60) were treated with 0.001 to 10 μM 5-azacytidine (Sigma) for 24, 48, and 72 h; 5-azacytidine was added every 24 h. The antiproliferative effect of 5-azacytidine was measured using the cell counting kit-8 (Wako Chemicals).

Telomere, telomerase and TERRA: Telomere length and telomerase activity were measured as reported previously (Ohyashiki JH, Br J Cancer 2005; 92: 1942–1947). The telomeric localization of TERRA was determined by RNA-FISH with strand-specific telomeric DNA probes. Experiments were performed in denaturing conditions with or without RNase, and the number of TERRA signal-positive cells was measured.

Methylation: Bisulfite genomic DNA sequencing was performed using primers designed to recognize both methylated and unmethylated forms of the p16/INK4a and p15/INK4b promoter regions. For the genome-wide screening of DNA methylation patterns, the Human Methylation27 BeadChip (Illumina) was used.

Results: Demethylating effect of 5-azacytidine: The half maximal inhibitory concentration (IC50) of 5-azacytidine was 3.4 μM in U937, 3.6 μM in K562, and 1 μM in HL-60. Bisulfite genomic DNA sequencing revealed that the p15/INK4b promoter region was markedly demethylated in U937 cells after 72 h treatment with the IC50 dose of 5-azacytidine. Similarly, we noted genome-wide hypomethylation in 5-azacytidine-treated U937 cells using the Human Methylation27 BeadChip, whereas we noted only modest hypomethylation in 5-azacytidine-treated K562 and HL-60 cells.

Upregulation of TERRA and telomerase inhibition: Based on the results obtained from the methylation analysis, we identified the localization of TERRA in 5-azacytidine-treated U937 and K562 cells. We observed 0∼2 dots corresponding to TERRA per cell in untreated U937 or K562 cells, and the signals were not detected in RNaseA-treated samples. In U937 cells, TERRA signals significantly increased in accordance with the decrease in telomerase activity. In contrast, neither an increase in TERRA signals nor a decrease in telomerase activity was observed in K562 cells. This indicates that the upregulation of TERRA and telomerase inhibition were closely related to genome-wide hypomethylation.

Conclusion: There is emerging evidence for the clinical utility of demethylating agents, such as 5-azacytidine in myelodysplastic syndrome; however, the molecular mechanism of 5-azacytidine has not been fully elucidated. Our results indicate that 5-azacytidine induces the upregulation of TERRA, thereby inhibiting telomerase in U937 cells. Although there is still a long way to go before realizing the diagnostic and therapeutic uses of TERRA in leukemia patients, our study provided novel information on TERRA in the telomere and the telomerase biology of human leukemia.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C19.

Detection method for quantifying global DNA methylation by fluorescence correlation spectroscopy

A method for quantifying global DNA methylation using fluorescence correlation spectroscopy (FCS) has been established. The single-molecule methylation assay (SMMA) is based on two methodologies. One methodology, FCS, estimates the translational diffusion coefficient of molecules in solution, whereas the other methodology uses the high affinity of methyl-CpG-binding domain protein 2 (MBD2) to bind specifically to methylated DNA. We studied the specific binding rates of fluorescence-labeled MBD2 and methylated DNA from biological samples using the automated FCS system. Using a standard curve with methylated control DNA, we developed the SMMA index to assess the global DNA methylation level of the biological samples. A marked decrease in the SMMA index was observed when human leukemia cell lines (U937 and K562) were cultured with DNA demethylating agents. Our findings clearly indicate the applicability of SMMA as a simple and rapid tool for quantifying global DNA methylation. SMMA may prove useful for genome-wide comparative methylation analyses of malignancies and as an indicator of the demethylation effects of epigenetic drugs.

Clinical impact of down-regulated plasma miR-92a levels in non-Hodgkin's lymphoma

BACKGROUND

We undertook a study to evaluate the clinical relevance of miR-92a in plasma obtained from non-Hodgkin's lymphoma (NHL) patients, because the miR-17-92 polycistronic miRNA cluster plays a crucial role in lymphomagenesis and affects neo-angiogenesis.

METHODOLOGY/PRINCIPAL FINDINGS

Plasma miR-92a values in NHL were extremely low (<5%), compared with healthy subjects (P<.0001), irrespective of lymphoma sub-type. The very low plasma level of miR-92a increased in the complete response (CR) phase but did not reach the normal range, and the plasma level was lower again in the relapse phase. Patients in CR or CR unconfirmed with a plasma miR-92a level of less than the cut-off level showed a significantly high relapse rate compared with patients with normalized plasma miR-92a level.

CONCLUSIONS/SIGNIFICANCE

The current results therefore indicate that the plasma miR-92a value could be a novel biomarker not only for diagnosis but also for monitoring lymphoma patients after chemotherapy.

Impact on cell to plasma ratio of miR-92a in patients with acute leukemia: in vivo assessment of cell to plasma ratio of miR-92a

Background

Plasma microRNA (miRNA) has become a promising biomarker for detecting cancer; however, it remains uncertain whether miRNA expression levels in plasma reflect those in tumor cells. Our aim was to determine the biological relevance of miR-92a, which has been implicated as an oncomiR in both plasma and leukemia cells in patients with acute leukemia and to evaluate whether it could be a novel biomarker for monitoring these patients.

Results

We quantified the expression level of miR-92a in both cells and plasma by reverse transcription polymerase chain reaction in 91 patients with acute leukemia. We also determined miR-92a expression levels in peripheral blood mononuclear cells (PBMNC) from normal controls. We compared miR-92a expression in plasma with its expression in leukemia cells. Synthetic anti-miR-92a inhibitor was transfected into Raji and OM9;22 cells, and apoptosis was assessed. For in vivo assessment, 6-week-old female nude mice were injected with U937 cells, and miR-92a expression in plasma and tumors was measured. The level of miR-92a expression in fresh leukemia cells was highly variable compared with PBMNC, but significantly lower compared with CD34-positive cells obtained from healthy volunteers. We also noticed that miR-92a was preferentially expressed in acute lymphoblastic leukemia (ALL) cells in comparison with acute myeloid leukemia (AML) cells. More specifically, cellular miR-92a expression was significantly increased in a subset of ALL cells, and ALL patients with overexpressed miR-92a had poor prognoses. The anti-miR-92a inhibitor-treated Raji and OM9;22 cells revealed an increase of apoptotic cells. Notably, the cell to plasma ratio of miR-92a expression was significantly higher in both AML and ALL cells compared with PBMNC from healthy volunteers. In tumor-bearing mice, the plasma miR-92a level was significantly decreased in accordance with tumor growth, while tumor tissue was strongly positive for miR-92a.

Conclusions

The miR-92a expression in leukemia cells could be a prognostic factor in ALL patients. The inverse correlation of miR-92a expression between cells and plasma and the cell to plasma ratio may be important to understanding the clinical and biological relevance of miR-92a in acute leukemia.

Reduced fertility with impairment of early-stage embryos observed in mice lacking Lgr4 in epithelial tissues

Lgr4 is one of the genes identified as novel G protein-coupled receptor genes designated Lgr4-Lgr8, with high homology with FSH receptor, LH receptor, and TSH receptor genes, but studies of Lgr4-mutant mice have suggested that Lgr4 has essential functions in development. This is the first report describing the relationship between the functions of Lgr4 and female reproductive systems.

Characterization of newly established clonal oviductal cell lines and differential hormonal regulation of gene expression

Oviductal functions have been studied mainly in primary epithelial cell culture and organ culture. However, secretory cells and ciliated cells coexist in the epithelium, and the small size of the oviduct limits the sources of both epithelial and stromal cells. To circumvent the limits, we attempted to establish clonal cell lines from an oviduct of a p53-deficient mouse. An oviduct was enzymatically digested and cultured in medium containing 10% fetal calf serum supplemented with estradiol-17beta. Morphologically distinct clones (10 epithelial and 4 fibroblastic clones) were established, and all clones expressed estrogen receptor alpha and progesterone receptor. Expression of a mouse oviduct-specific glycoprotein gene as a marker of secretory cells was limited in one clone and was stimulated by estrogens and suppressed by progesterone. Expression of helix factor hepatocyte nuclear factor/forkhead homologue-4 gene as a marker of ciliated cells was limited in two clones and was suppressed by estrogens. The two genes were never coexpressed in any clones. The results strongly suggest that the oviductal epithelium consists of two functionally determined populations. To our knowledge, this is the first establishment of functional clonal cell lines of the oviduct and makes it possible to study independently two oviductal functions, secretion and ciliogenesis.

An evidence of stromal cell populations functionally linked with epithelial cell populations in the mouse oviduct

The oviductal epithelium consists of two major cell populations, secretory cells and cilial cells. In a previous report, we established clonal cell lines from the epithelium and stroma of an oviduct which allowed us to analyze stromal contribution to epithelial functions. Three stromal cell lines were co-cultured in separated apparatus with 3 epithelial cell lines, respectively. Two stromal cell lines preferentially stimulated mogp-1 expression on secretory cells and the stimulation was additive with estrogen. The lines had no effect on cilial cells. One stromal cell line preferentially stimulated foxj1 expression on cilial cells and the stimulation relieved suppression by estrogen. The line had no effect on secretory cells. Experiments with conditioned media of the stromal cells confirmed the results of co-culture experiments, suggesting that the oviductal stroma contains multiple cell populations preferentially regulating or modulating specific cell populations of the epithelium via diffusible factors.

Ambulation-promoting effect of peppermint oil and identification of its active constituents

Various plant-derived essential oils (EOs) have traditionally been used in the treatment of mental disorders, despite a lack of scientific evidence. In a previous study, we demonstrated that certain EOs possess behavioral effects, a finding that supports our original hypotheses that EOs possess psychoactive actions. The present study was conducted in order to obtain further evidence to support our hypothesis. Peppermint oil, a type of EO, is believed to be effective for treating mental fatigue. When the oil was administered intraperitoneally to ICR mice, the ambulatory activity of mice increased dramatically. We identified alpha-pinene, beta-pinene, (R)-(+)-limonene, 1,8-cineol, isomenthone, menthone, menthol, (R)-(+)-pulegone, menthyl acetate and caryophyllene as constituent elements of peppermint oil by GC-MS analysis. We then examined the effect of each constituent element of peppermint oil on ambulatory activity in mice. Intraperitoneal administration of 1,8-cineol, menthone, isomenthone, menthol, (R)-(+)-pulegone, menthyl acetate and caryophyllene significantly increased ambulatory activity in mice, suggesting that these chemicals are the behaviorally active elements of peppermint oil. Intravenous administration of these substances to mice induced a significant increase in ambulatory activity at much lower doses. The present study provides further evidence demonstrating that EOs possess pharmacological actions on behavior. In addition, our finding revealed that the action of peppermint oil comes from its constituent elements.