Hodgkin Lymphoma Cell Line L1236 Research Articles

Expression of A New Endogenous Retrovirus-Associated Transcript in Hodgkin Lymphoma Cells.

During characterization of a cDNA library from the Hodgkin lymphoma (HL) cell line L-1236, we discovered a new transcript derived from chromosome 1 at the long intergenic non-protein coding RNA 1768 (LINC01768)/colony stimulating factor 1 (CSF1) region. The first exon of this transcript from Hodgkin lymphoma cells (THOLE) starts in the predicted exon 4 of LINC01768 and is part of an endogenous retrovirus (ERV) from the HUERS-P1/LTR8 family. High expression of THOLE was only detectable in HL cell line L-1236. The expression of THOLE in L-1236 cell is another example for ERV/LTR-associated gene expression in HL cells. At the genome level, the HUERS-P1/LTR8 region including THOLE is only present in Hominoidea. The influence of ERV/LTRs on gene expression might explain the characteristic phenotype of human HL.

Continuous Exposure to Bendamustine (BDM) Results in Stable Upregulation of CD30 and Increased Sensitivity to Brentuximab Vedotin (BV) in Tumor Cells of Hodgkin Lymphoma (HL)

Background: Given the consistent antitumor activity and favorable toxicity profile in heavily pretreated patients, BDM represents a suitable platform for combination with target-based agents in the setting of recurrent HL. The anti-CD30 antibody-monomethyl auristatin E (MMAE) conjugate brentuximab vedotin (BV) appears a most valuable candidate by coupling an impressive clinical activity with the lack of serious overlapping toxicities with BDM. While the combination of BDM and BV is being evaluated in Phase II studies, no information is available as to possible mechanisms through which BDM may regulate the antitumor efficacy of BV towards HL cells.Methods: We evaluated the effects of acute and extended exposure to BDM on CD30 expression and sensitivity to the cytotoxic activity BV in the HL cell line L1236. Cells were cultured in the presence of BDM at its IC50 for different time points of acute exposure. Through continuous exposure to increasing concentrations (25.0, 50.0, 75.0, 100 micromol/L) of BDM, we then performed a serial in vitro selection for BDM-resistant (R) L1236 cell clones and determined their CD30 expression by flow cytometry, qRT-PCR, and Western analysis.Results: Acute exposure to BDM (48 to 72 hrs) of L1236 cells led to a sizeable upregulation of CD30 as shown by flow cytometry. This effect was unsustained since CD30 intensity returned to baseline levels upon culturing in BDM-free medium for one week. Expression of other surface antigens, i.e. HLA-DR, was unaffected by BDM while acute exposure to doxorubicin and other cytotoxic drugs did not modify the CD30 expression. We established four L1236-derived cell clones (R25, R50, R75 and R100) able to proliferate across the different concentrations of BDM with growth/viability curves superimposable to native cells. Clonal identity among clones and with parental cells was confirmed by sequencing of V3-21 (FR2/FR3) and JH3-JH4 Ig DNA regions. All R-clones displayed an up to 900% increase in CD30 median fluorescence intensity, relative to native L1236 cells (Figure 1A). The sustained CD30 upregulation was confirmed by qRT-PCR and Western blotting since R-clones expressed up to 10-fold higher levels of CD30-specific mRNA and CD30-specific 120 kDa components as compared to parental cells. To rule out a general upregulation of surface molecules as a result of the chronic exposure to BDM we evaluated the expression of other surface antigens. As opposed to CD30, HLA-DR and PDL-1 relative transcript levels and cell surface expression were significantly reduced in R-cells. Intriguingly, BDM-induced CD30 upregulation was specific to L1236 cells since extended exposure to BDM did not modify expression levels of CD30 in other lymphoma cell types (SUDHL1, JEKO). BDM-induced CD30 overexpression significantly enhanced the sensitivity of HL cells to the cytotoxic effects of BV. MTS assay showed the IC50 of R100 cells to BV shifted to 0.21 ± 0.06 mcg/mL (48 hrs) and 0.19 ± 0.05 mcg/mL (72 hrs) vs. 3.16 ± 0.75 mcg/mL (48 hrs) and 3.87 ± 0.68 mcg/mL (72 hrs) of parental cells, a 15- and 20-fold increase, respectively (p<0.001; Figure 1B). Finally, qRT-PCR studies disclosed that R-clones did not show any upregulation of the drug exporter MDR1 gene, involved in MMAE extrusion and BV resistance in HL cells, as compared to parental L1236 cells.Conclusions: Whileacute exposure to BDM induced a transient upregulation of CD30, extended exposure to the agent resulted in the selection of L1236 subclones with a stable overexpression of surface CD30 and reduced levels of HLA-DR and PDL-1. Upregulation of CD30 was associated with a significantly enhanced sensitivity to cytotoxic effects of BV. Translated into a clinical context these findings suggest that HL patients progressing upon BDM treatment may turn exquisitely sensitive to BV and prompt the exploration of a sequential treatment with BDM and BV in late and earlier disease phases. Results also provide a mechanistic insight as to the efficacy of the BDM-BV combination in HL, highlighting non-overlapping resistance pathways between BDM and MMAE. BDM-induced selection of CD30hi, HLA-DRlow/PDL-1low tumor cell clones might be relevant to the design of novel treatment strategies for HL based on the combination of BDM with BV and anti-PD1/PDL-1 antibodies. [Display omitted] [Display omitted] DisclosuresPinto:Takeda: Research Funding; Takeda, Celgene, Roche, TEVA: Honoraria.

Early growth response gene (EGR)-1 regulates leukotriene D4-induced cytokine transcription in Hodgkin lymphoma cells

Classical Hodgkin lymphoma (cHL) has a unique pathological feature characterized by a minority of malignant Hodgkin Reed–Sternberg (H–RS) cells surrounded by numerous inflammatory cells. Cysteinyl-leukotrienes (CysLTs) are produced by eosinophils, macrophages and mast cells in the HL tumor microenvironment. In the present study we have explored the signal transduction pathways leading to leukotriene (LT) D4 induced expression of cytokines in the Hodgkin lymphoma cell line L1236 and KM-H2. Stimulation of L1236 and KM-H2 cells with LTD4 led to a concentration- and time-dependent increase at the transcriptional level of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-8, chemokine (C-C motif) ligand 3 (CCL3) and CCL4. The expression of several transcription factors was induced upon stimulation of Hodgkin cell lines with LTD4. Among these, EGR-1 was required for cytokine production. Inhibition of EGR-1 expression using shEGR-1 transduced by lentivirus led to suppression of the expression of TNF-α and IL-6. The effect of LTD4 on the expression of transcription factors and cytokines were also blocked by the specific CysLT1 receptor antagonist zafirlukast. These results demonstrate that EGR-1 plays a critical role in LTD4-induced cytokine transcription in Hodgkin cell lines.

Abstract B269: Effects of blocking aberrantly expressed CSF-1R in Hodgkin lymphoma.

Abstract The human genome contains a large number of repetitive elements that have been suspected to play a role in human diseases. Recent literature has shown that aberrant activation of one of these repetitive elements, a long terminal repeat (LTR), leads to lineage inappropriate expression of the CSF-1 receptor (CSF-1R) transcript in Hodgkin's lymphoma (HL) clinical samples and cell lines. CSF1-R, also known as Feline McDonough Sarcoma (FMS), is the receptor for CSF-1 and IL-34, and under normal circumstances it plays an important role in monocyte survival, proliferation, and differentiation as well as osteoclast generation. Aberrant expression of CSF-1R has been shown previously to support proliferation and survival in HL cells. To confirm the role of CSF-1R in HL, we determined that 17 of 17 HL clinical samples and 7 of 7 HL cell lines were positive for the aberrant CSF-1R transcript by TaqMan and traditional PCR, while non-HL cell lines were negative for the aberrant CSF-1R transcript. The HL lines were further characterized for surface expression of CSF-1R by flow cytometry and CSF-1 secretion by ELISA. L-1236 cells expressed the highest levels of CSF-1R and CSF-1. Treatment of the HL cell lines with CSF-1R-Fc, resulted in reduced viability in four of the five lines, consistent with the hypothesis that HL cell lines are sensitive to CSF-1 as a growth factor. Additionally, it was found that treating the L-1236 HL cell line with the CSF-1R small molecule inhibitor JNJ-40646527 had a significant effect on viability of the HL cell line L-1236, with an IC50 of 264 nM at 72 hrs. JNJ-40646527 did not have a significant effect on the viability of several other HL cell lines. These results indicate that aberrant LTR driven CSF-1R expression may play a role in the pathogenesis of Hodgkin's lymphoma (HL) and could be a potential target for Hodgkin's lymphoma therapy. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B269. Citation Format: Liam Campion, Nikki Deangelis, Catherine Ferrante, Raluca Verona, Shobha Seetharam, Carl Manthey, Linda Snyder. Effects of blocking aberrantly expressed CSF-1R in Hodgkin lymphoma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B269.

Metabolism of Anandamide into Eoxamides by 15‐Lipoxygenase‐1 and Glutathione Transferases

Human 15-lipoxygenase-1 (15-LO-1) can metabolize arachidonic acid (ARA) into pro-inflammatory mediators such as the eoxins, 15-hydroperoxyeicosatetraenoic acid (HPETE), and 15-hydroxyeicosatetraenoyl-phosphatidylethanolamine. We have in this study investigated the formation of various lipid hydroperoxide by either purified 15-LO-1 or in the Hodgkin lymphoma cell line L1236, which contain abundant amount of 15-LO-1. Both purified 15-LO-1 and L1236 cells produced lipid hydroperoxides more efficiently when anandamide (AEA) or 2-arachidonoyl-glycerol ester was used as substrate than with ARA. Furthermore, L1236 cells converted AEA to a novel class of cysteinyl-containing metabolites. Based on RP-HPLC, mass spectrometry and comparison to synthetic products, these metabolites were identified as the ethanolamide of the eoxin (EX) C(4) and EXD(4). By using the epoxide EXA(4)-ethanol amide, it was also found that platelets have the capacity to produce the ethanolamide of EXC(4) and EXD(4). We suggest that the ethanolamides of the eoxins should be referred to as eoxamides, in analogy to the ethanolamides of prostaglandins which are named prostamides. The metabolism of AEA into eoxamides might engender molecules with novel biological effects. Alternatively, it might represent a new mechanism for the termination of AEA signalling.

Transcriptional Deregulation of Homeobox Gene ZHX2 in Hodgkin Lymphoma

Abstract 2629Hodgkin/Reed-Sternberg (HRS) cells represent the malignant fraction of infiltrated lymph nodes in Hodgkin lymphoma (HL). Although HRS cells display multiple chromosomal aberrations, few are recurrent and the targeted genes unknown. However, understanding the pathology of HL and developing rational therapies may well require identification and characterization of these genes and their deregulating mechanisms. Recently, we have identified a novel chromosomal rearrangement in HL cell line L-1236, t(4;8)(q27;q24), which targets ZHX2 at the recurrent breakpoint 8q24. ZHX2 encodes a transcription factor of the homeobox gene family and possesses tumour suppressor activity connected with a worse prognosis in HL-related multiple myeloma. Comparative expression analysis in HL cell lines and primary hematopoietic cells indicated aberrant downregulation in HL as well. In L-1236 the translocation breakpoint at 8q24 deletes the regulative far upstream region of ZHX2, indicating loss of activating elements. Therefore, we have looked for potential binding sites within this deleted region to analyze deregulation of this B-cell tumour suppressor gene. Accordingly, we identified two transcription factors, homeodomain protein MSX1 and bZIP protein XBP1, regulating ZHX2 expression. SiRNA-mediated knockdown and reporter gene analyses indicated that both factors activated transcription of ZHX2 directly via their corresponding binding sites. Furthermore, MSX1-cofactor histone H1C mediated repression of ZHX2 and showed enhanced expression levels in L-1236. As analyzed by fluorescence in situ hybridization (FISH) and genomic arrays, the gene loci of MSX1 at 4p16 and H1C at 6p21 were rearranged in several HL cell lines, correlating with their altered expression activity. As compared to primary hematopoietic cells, XBP1 expression was reduced in 6/7 HL cell lines while one cell line showed elevated levels, corresponding to a chromosomal rearrangement therein. Interestingly, the neighbouring pro-apoptotic genes EDEM1 and BHLHE40 were removed by del(3p26) in this cell line and activated by XBP1 in other HL cells. Taken together, our results demonstrate multiple mechanisms decreasing expression of tumour suppressor gene ZHX2 in HL cells: loss of enhancing binding sites, reduced expression of activators MSX1 and XBP1, and overexpression of MSX1-corepressor H1C. Moreover, chromosomal deregulations of genes involved in this regulative network highlight their role in development and malignancy of B-cells. Disclosures:No relevant conflicts of interest to declare.

T(4;8)(q27;q24) in Hodgkin lymphoma cells targets phosphodiesterase PDE5A and homeobox gene ZHX2

Hodgkin/Reed-Sternberg (HRS) cells represent the malignant fraction of infiltrated lymph nodes in Hodgkin lymphoma (HL). Although HRS cells display multiple chromosomal aberrations, few are recurrent and the targeted genes unknown. However, understanding the pathology of HL and developing rational therapies may well require identifying putative deregulated genes. Here, we analyzed the karyotype of the well-defined HL cell line L-1236 by spectral karyotyping and identified multiple abnormalities, therein, notably t(4;8)(q27;q24) which includes two breakpoint regions previously highlighted in HL. Target genes at 4q27 and 8q24 were shortlisted by high density genomic arrays and fluorescence in situ hybridization. Expression analysis of candidate target genes revealed conspicuous activation of phosphodiesterase PDE5A at 4q27 and inhibition of homeobox gene ZHX2 at 8q24. Treatment of L-1236 with PDE5A-inhibitor sildenafil or with siRNA directed against PDE5A and concomitant stimulation with cyclic guanosine monophosphate (cGMP) resulted in enhanced apoptosis, indicating PDE5A as an oncogene. Expression profiling of L-1236 cells following siRNA-mediated knockdown of ZHX2 showed inhibition of genes regulating differentiation and apoptosis, suggesting tumor suppressor activity of ZHX2. Downstream genes included STAT1 and several STAT1-target genes, indicating activation of STAT1-signaling by ZHX2 as analyzed by RQ-PCR and western blot. Taken together, we have identified a novel aberration with recurrent breakpoints in HL, t(4;8)(q27;q24), which activate PDE5A and repress ZHX2, deregulating apoptosis, differentiation, and STAT1-signaling in HL cells.

Biosynthesis of 14,15‐Hepoxilins in Human L1236 Hodgkin Lymphoma Cells and Eosinophils

Hepoxilins are epoxy alcohols synthesized through the 12-lipoxygenase (12-LO) pathway in animal cells. The epidermis is the principal source of hepoxilins in humans. Here we report on the formation of novel hepoxilin regioisomers formed by the 15-LO pathway in human cells. The Hodgkin lymphoma cell line L1236 possesses high 15-lipoxygenase-1 (15-LO-1) activity and incubation of L1236 cells with arachidonic acid led to the formation of 11(S)-hydroxy-14(S),15(S)-epoxy 5(Z),8(Z),12(E) eicosatrienoic acid (14,15-HxA(3) 11(S)) and 13(R)-hydroxy-14(S),15(S)-epoxy 5(Z),8(Z),11(Z) eicosatrienoic acid (14,15-HxB(3) 13(R)). In addition, two hitherto unidentified products were detected and these products were collected and analyzed by positive ion electrospray tandem mass spectrometry. These metabolites were identified as 11(S),15(S)-dihydroxy-14(R)-glutathionyl-5(Z),8(Z),12(E)-eicosatrienoic acid (14,15-HxA(3)-C) and 11(S),15(S)-dihydroxy-14(R)-cysteinyl-glycyl-5(Z),8(Z),12(E)-eicosatrienoic acid (14,15-HxA(3)-D). Incubation of L1236 cells with synthetic 14,15-HxA(3) 11(S) also led to the formation of 14,15-HxA(3)-C and 14,15-HxA(3)-D. Several soluble glutathione transferases, in particular GST M1-1 and GST P1-1, were found to catalyze the conversion of 14,15-HxA(3) to 14,15-HxA(3)-C. L1236 cells produced approximately twice as much eoxins as cysteinyl-containing hepoxilins upon stimulation with arachidonic acid. Human eosinophils, nasal polyps and dendritic cells selectively formed 14,15-HxA(3) 11(S) and 14,15-HxB(3) 13(R) stereoisomers, but not cysteinyl-containing hepoxilins, after stimulation with arachidonic acid. Furthermore, purified recombinant 15-LO-1 alone catalyzed the conversion of arachidonic acid to 14,15-HxA(3) 11(S) and 14,15-HxB(3) 13(R), showing that human 15-LO-1 possesses intrinsic 14,15-hepoxilin synthase activity.

Interleukin-13 stimulation of the mediastinal B-cell lymphoma cell line Karpas-1106P induces a phenotype resembling the Hodgkin lymphoma cell line L1236

Primary mediastinal B-cell lymphoma (PMBCL) and Hodgkin lymphoma (HL) share many biological and clinical characteristics supporting a common pathogenetic pathway. Interleukin (IL)-13 has an important pathophysiological role in HL. In this study, we asked the question of whether IL-13 is a major contributor to the observed difference in features of inflammation between HL and PMBCL. Expression of IL-13 and IL-4 receptors was studied by flow cytometry, expression of a functional cysteinyl leukotriene receptor type 1 (CysLT1R) was investigated by calcium flux measurement, expression and activity of 15-lipoxygenase type 1 (15-LO-1) was determined by Western blot and reversed-phase high-performance liquid chromatography, respectively, and cytokines were quantified by Bioplex detection. Stimulation of the PMBCL cell line Karpas-1106P with IL-13 or IL-4 induced a proinflammatory phenotype similar to that of the HL cell line L1236. Upon interleukin stimulation of the PMBCL cell line, the cellular size increased and cells became multinucleated. Cells also expressed CysLT1R and 15-LO-1, and produced the proinflammatory eoxins. The IL-13 or IL-4 treated PMBCL cell line and the HL cell line secreted a similar set of cytokines such as IL-6, tumor necrosis factor-alpha, interferon-inducible protein-10, interferon-gamma, and RANTES. IL-13 or IL-4 stimulation of the PMBCL cell line Karpas-1106P induced an inflammatory phenotype that resembles that of the HL cell line. Our results suggest that the autocrine release of IL-13 in HL is one critical factor that can at least partly explain the difference in phenotype between these two lymphoma entities.

Three-dimensional culturing of the Hodgkin lymphoma cell-line L1236 induces a HL tissue-like gene expression pattern

To overcome some limitations of in vitro established cell-line tumor models for Hodgkin lymphoma (HL), we explored whether culturing in a three-dimensional (3D) matrix could improve the quality of the model. We used a novel designer peptide based self-organizing matrix. The gene expression profile of the 3D-cultured HL derived cell-line L1236 was compared with that of suspension-cultured (2D) L1236, as well as to the gene expression profile found in HL tumor samples. To validate our results we also included a gene expression data set of laser captured Hodgkin-Reed – Sternberg (H-RS) cells. The gene expression profiles were analyzed using Affymetrix™ technology. We found that the 3D culture affected gene expression of a HL derived cell-line inducing a more tumor-related expression profile. 3D culture affected the expression of 500 genes in L1236, upregulating genes involved in immune response and apoptosis and downregulating genes involved in cell division. It also affected genes involved in actin filament polymerization.

Inhibition of Signal Transducer and Activator of Transcription 6 Activity in the Hodgkin Lymphoma Cell Line L1236 Induces Growth Inhibition and Apoptosis.

Signal transducer and activator of transcription 6 (STAT6) plays a central role in interleukin (IL)-4 and -13 signaling. Upon binding of the cognate receptors by these cytokines, STAT6 becomes phosphorylated by Jak family kinases and subsequently translocates to the nucleus where transcription of its target genes is regulated. Expression of IL-13 and its receptor are common features of Hodgkin lymphoma (HL) tumor cells, the so-called Hodgkin Reed-Sternberg (H-RS) cells, in which this cytokine has been shown to act as an autocrine growth factor. Consequently, constitutively phosphorylated STAT6 with a nuclear localization is a common and distinctive feature of H-RS cells in classical HL. We knocked down STAT6 expression in the HL cell line L1236 with small interfering RNA (siRNA) and found that inhibition of STAT6 activity results in cell growth inhibition, decreased viability and increased apoptosis. The results depict a central role of STAT6 in the growth of H-RS cells and indicate that STAT6 could be a potential target for therapeutic intervention in HL. Moreover, in order to identify the target genes of this transcription factor in H-RS cells, a combined approach of RNA interference and microarray is performed and the results will be presented.