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Chromosome band 8q24 is the most frequently amplified locus in various types of cancers. MYC has been identified as the primary oncogene at the 8q24 locus, whereas a long noncoding gene, PVT1, which lies adjacent to MYC, has recently emerged as another potential oncogenic regulator at this position. In this study, we established and characterized a novel cell line, AMU-ML2, from a patient with diffuse large B-cell lymphoma (DLBCL), displaying homogeneously staining regions at the 8q24 locus. Fluorescence in situ hybridization clearly detected an elevation in MYC copy numbers corresponding to the homogenously staining region. In addition, a comparative genomic hybridization analysis using high-resolution arrays revealed that the 8q24 amplicon size was 1.4 Mb, containing the entire MYC and PVT1 regions. We also demonstrated a loss of heterozygosity for TP53 at 17p13 in conjunction with a TP53 frameshift mutation. Notably, AMU-ML2 cells exhibited resistance to vincristine, and cell proliferation was markedly inhibited by MYC-shRNA-mediated knockdown. Furthermore, genes involved in cyclin D, mTOR, and Ras signaling were downregulated following MYC knockdown, suggesting that MYC expression was closely associated with tumor cell growth. In conclusion, AMU-ML2 cells are uniquely characterized by homogenously staining regions at the 8q24 locus, thus providing useful insights into the pathogenesis of DLBCL with 8q24 abnormalities.

The shift in energy metabolism from oxidative phosphorylation to glycolysis can serve as a target for the inhibition of cancer growth. Here, we examined the metabolic changes induced by 2-deoxyglucose (2-DG), a glycolysis inhibitor, in leukemia cells by metabolome analysis. NB4 cells mainly utilized glucose as an energy source by glycolysis and oxidative phosphorylation in mitochondria, since metabolites in the glycolytic pathway and in the tricarboxylic acid (TCA) cycle were significantly decreased by 2-DG. In THP-1 cells, metabolites in the TCA cycle were not decreased to the same extent by 2-DG as in NB4 cells, which indicates that THP-1 utilizes energy sources other than glucose. TCA cycle metabolites in THP-1 cells may be derived from acetyl-CoA by fatty acid β-oxidation, which was supported by abundant detection of carnitine and acetylcarnitine in THP-1 cells. 2-DG treatment increased the levels of pentose phosphate pathway (PPP) metabolites and augmented the generation of NADPH by glucose-6-phosphate dehydrogenase. An increase in NADPH and upregulation of glutathione synthetase expression resulted in the increase in the reduced form of glutathione by 2-DG in NB4 cells. We demonstrated that a combination of 2-DG and inhibition of PPP by dehydroepiandrosterone (DHEA) effectively suppressed the growth of NB4 cells. The replenishment of the TCA cycle by fatty acid oxidation by carnitine palmitoyltransferase in THP-1 cells, treated by 2-DG, might be regulated by AMPK, as the combination of 2-DG and inhibition of AMPK by compound C potently suppressed the growth of THP-1 cells. Although 2-DG has been effective in preclinical and clinical studies, this treatment has not been fully explored due to concerns related to potential toxicities such as brain toxicity at high doses. We demonstrated that a combination of 2-DG and DHEA or compound C at a relatively low concentration effectively inhibits the growth of NB4 and THP-1 cells, respectively. These observations may aid in the identification of appropriate combinations of metabolic inhibitors at low concentrations which do not cause toxicities.

Introduction: Primary refractory DLBCL is an extremely difficult condition to treat and represent an unmet medical need. The clarification of the molecular pathogenesis of this disease can contribute the development of new therapeutic possibilities. PVT1 is located adjacent to MYC at 8q24 and a non-protein coding gene. PVT1 produces a variety of long non-coding RNAs (lncRNAs) and has now emerged as a potential regulator in the pathogenesis of a lot of cancers. However, the precise biological and clinical significance of PVT1 remains largely unknown. In this study we established a novel human DLBCL cell line with hsr (homogeneous staining region) of 8q24 inducing high expression of PVT1 lncRNAs, named AMU-ML2. The cell line was established from a patient with primary refractory DLBCL before initiation of chemotherapy. We analyzed the genetic characteristics and investigated the drug sensitivity of the cell line in comparison with other B-cell lymphoma cell lines which had 8q24 abnormalities. Case: A 64-year-old man was diagnosed as DLBCL involved with bone marrow and pleural effusion. He was refractory to initial R-CHOP and subsequent R-hyper-CVAD/MA therapy and died of Trichosporon asahiisepsis 6 months after diagnosis. His lymphoma cells at diagnosis were positive for CD19, CD20, BCL6 and HLA-DR, and negative for CD3, CD5, CD10, cyclinD1, BCL2, MUM1, TP53 and EBER by flow cytometry and/or immunohistochemical staining, indicative of germinal center B-cell-like (GCB) DLBCL. The representative karyotype of cells was 46,XY, including add(6)(p11), add(8)(q24), hsr 8q24, add(9)(p13) and add(17)(p11.2). Establishment of the cell line: After 2 weeks of culture, the cells in pleural effusion collected before chemotherapy started to grow in suspension. The cell line was designated as AMU-ML2 after confirmation that the cells started growing again after the conventional freeze-thaw procedure. Materials and methods: B-cell lymphoma cell lines; AMU-ML2, SU-DHL-10, Raji, P3HR-1 and VAL were used in the present study. These cell lines had t(8;14)(q24;q32) or 8q24 amplification. The genomic aberration of AMU-ML2 was analyzed by cytogenetics including G-banding and FISH (fluorescence in situ hybridization) combined with array-CGH (SurePrint G3, Agilent). The TaqMan real time RT-PCR was used for measurement of expression levels of MYC and PVT1. MTT assay was used for the cell proliferation to analyze the drug sensitivities of cyclophosphamide, doxorubicin, vincristine (VCR) and prednisolone. Results: AMU-ML2 cells showed same immunophenotypic feature and karyotype as the primary sample from the patient. FISH using a MYC/IGH probe set showed no fusion signal for IGH and MYC; however, the MYC copy number was extremely increased, corresponding to hsr on chromosome 8q24. Array-CGH revealed that a 1,462 kb region, containing both the entire MYC and PVT1 genes at 8q24.21, was amplified, with greater than 20 copies present in cells (Figure 1). In addition to amplification of the MYC/PVT1 region at 8q24, 14 additional copy number alterations were detected. These included segment losses on 6p22.1-6p21.31 and 17p13 led to the LOH of human leukocyte antigen (HLA) loci and TP53, respectively (Figure 1). Using the real time RT-PCR, the expression level of the PVT1 lncRNAs were highest in AMU-ML2 among other B-cell lymphoma cell lines that we used, while the expression level of MYC in AMU-ML2 was relatively low. The proliferation rate of AMU-ML2 was significantly higher after 72-h exposure to VCR (100, 500 and 1,000 nM) compared with other cell lines (Figure 2). Discussion: AMU-ML2 was established in 2-week culture from a refractory patient before starting the chemotherapy, therefore this cell line seems to reflect the real nature of primary refractory DLBCL, not related to chemotherapy and/or cell culture. MYC amplification and the LOH of TP53 and HLA may contribute to the development of lymphoma in our case. High expression of PVT1 lncRNAs was likely to be more related with drug resistance to VCR than MYC expression, although AMU-ML2 had co-amplification of MYC and PVT1. Thus, AMU-ML2 can provide insight into the genetic and biological features and the therapeutic approaches in primary refractory DLBCL. Disclosures Ueda: Mundipharma KK: Consultancy; Kyowa Hakko Kirin: Research Funding.

Despite recent progress in treatment for multiple myeloma (MM), a complete cure remains elusive. To further improve the therapeutic outcome of patients with MM, elucidation of the pathology of refractory cases is important. Hyperamylasemia, which is associated with ectopic amylase (AMY) production by MM cells, is a rare condition, and it has been reported to present with poor prognosis showing rapid tumor growth, extramedullary tumor mass formation, and refractoriness of the condition. However, to date, there have been no biological analyses of MM cells ectopically producing AMY. In this study we generated transfectants that stably expressed AMY with human MM cells, and investigated the impact that ectopic AMY production has on tumor proliferation and changes in drug susceptibility in vitro and in vivo. Two human MM cell lines (RPMI8226 and KMS11) and the cDNA encoding AMY1 were used to establish transfectants with ViraPower™ Lentiviral Gateway Expression Kit (Invitrogen), because the increased AMY isotype was salivary type, which is coded in AMY1, in all MM patients previously reported. The constitutive expression and production of AMY1 were confirmed in the AMY-transfectants (8226/AMY and KMS11/AMY), while they were not in the mock controls. These transfectants were assayed for proliferation and apoptosis after exposure to dexamethasone (Dex), bortezomib (Bz) and lenalidomide (Len) in vitro. The anti-myeloma activity of Bz was also tested in vivo in a xenograft model generated by injecting 8226/AMY or the mock cells into NOD-SCID mice. 8226/AMY had no growth advantage in vitro but grew rapidly when subcutaneously transplanted in mice compared with the mock control (2,177±878 vs 970±131 mm3, p = 0.044). 8226/AMY showed a higher cell proliferation rate than the mock control in vitro when treated with Dex (40uM), Bz (2nM), and Len (1mM). The number of apoptotic 8226/AMY cells decreased after exposure to Bz and Len, but the number after exposure to Dex was equivalent compared with the mock control by the Annexin / Propidium Iodide assay. Therefore, 8226/AMY became less sensitive to Bz and Len partly through the inhibition of apoptosis induced by these drugs. 8226/AMY grew rapidly subcutaneously in mice compared with the mock control when treated with Bz (0.3mg/kg, twice weekly) (p = 0.017). As for KMS11/AMY, the AMY-transfectant showed a higher proliferation rate than the mock control in vitro. KMS11/AMY showed reduced susceptibility to Dex, no change in the susceptibility to Bz, and an enhanced susceptibility to Len unexpectedly in comparison with the mock control. The reason for a difference in the effect of ectopic AMY expression on the susceptibility to anti-MM drugs between 8226/AMY and KMS11/AMY is unclear; however, it might be due to the nature of their parental cells. No significant difference was observed in the gene expression profiling between both AMY-transfectants and each of the respective mock controls, except for AMY1, suggesting that ectopic AMY expression did not affect the expression level of the specific gene in MM. In conclusion, we found that 8226/AMY had reduced susceptibility to Dex, Bz, and Len in vitro and also rapid tumor growth with a weakened anti-tumor effect of Bz in vivo. All of these were consistent with the clinical course of previously reported patients with ectopic AMY-producing MM. On the other hand, KMS11/AMY showed an enhanced susceptibility to Len compared with the mock control, indicating that Len might be effective for some patients with AMY-producing MM. Our data provided beneficial clues for elucidating the molecular pathology and developing a treatment strategy for this clinical setting. Disclosures No relevant conflicts of interest to declare.