Hepatocellular carcinoma (HCC) is the most common primary liver carcinoma and has one of the highest mortality rates of all cancers. The γδ T cells could infiltrate HCC and have demonstrated potent tumor-killing capacity. Here, we found that in peripheral blood, the vast majority of γδ T cells were Vδ2 T cells. In HCC patients, the frequency of Vδ2 T cells was significantly lower than in controls. γδ T cells that were harvested directly ex vivo possessed very limited capacity to eliminate Zol-loaded HCC cell lines, even at a high effector to target ratio. In vitro expansion with Zol could significantly increase the capacity of γδ T cells to eliminate HCC cell lines. But even with in vitro expansion, the γδ T cells from HCC patients presented significantly lower cytotoxic capacity than the γδ T cells from healthy individuals. The expression of IL-2 and IL-21 by γδ T cells was significantly lower in HCC patients than in control volunteers. Supplementing recombinant human IL-2 and IL-21 in the in vitro expansion culture increased the cytotoxic capacity of γδ T cells. In addition, the frequency of PD-1

Vγ9Vδ2 T cells are the main γδ T subset in the peripheral blood and lymphoid organs. Previous studies have shown that Vγ9Vδ2 T cells could expand in the presence of phosphoantigens and IL-2 and exert antitumor functions. However, their potency was limited because sustained proliferation could not be achieved, possibly due to exhaustion caused by prolonged antigenic stimulation. In this study, we examined the proliferative response of Vγ9Vδ2 T cells to IL-21, a cytokine previously shown to promote NK cell and CD8 T cell cytotoxicity. We found that IL-21 could significantly improve the proliferation of phosphoantigen-stimulated Vγ9Vδ2 T cells in a dose-dependent manner. However, in acute myeloid leukemia (AML) patients, the efficacy of IL-21 was significantly reduced. Vγ9Vδ2 T cells from AML patients exhibited lower expression of IL-21R, and required higher levels of IL-21 for expansion. IL-21-treated Vγ9Vδ2 T cells from AML patients presented lower increase in STAT1 phosphorylation than Vγ9Vδ2 T cells from healthy volunteers. Interestingly, AML Vγ9Vδ2 T cells presented significantly higher Tim-3 expression than healthy Vγ9Vδ2 T cells. IL-21 treatment further induced Tim-3 upregulation. Blocking Tim-3 increased the proliferation and the STAT phosphorylation in Vγ9Vδ2 T cells in response to IL-21. Together, these results demonstrated that IL-21 could significantly expand the Vγ9Vδ2 T cells, but its efficacy was limited since it also increased the expression of checkpoint molecule Tim-3.

Background: Waldenström macroglobulinemia (WM) is a rare, indolent B-cell lymphoma. Clinically, chromosome 6q deletion (6q del) including loss of the B lymphocyte-induced maturation protein 1 gene (BLIMP-1) is reported to be associated with poor prognosis. However, it remains unclear how the underlying biological mechanism contributes to the aggressiveness of WM with 6q del.
Methods: Here, we conducted oligonucleotide microarray analysis to clarify the differences in gene expression between WM with and without 6q del. Gene ontology (GO) analysis was performed to identify the main pathways underlying differences in gene expression. Eight bone marrow formalin-fixed paraffin-embedded samples of WM were processed for interphase fluorescence in situ hybridization analysis, and three were shown to have 6q del.
Results: GO analysis revealed significant terms including "lymphocyte activation" (corrected p value=6.68E-11), which included 31 probes. Moreover,
Conclusion: The present study suggested that the BCR signaling pathway and

Interleukin-21 receptor (IL-21R) is involved in the immunological regulation of immune cells and tumor progression in multiple malignancies. However, the potential molecular mechanisms through which non-coding RNAs (ncRNAs) modulate IL-21R signaling in gastric cancer (GC) remain elusive. In this study, the expression of IL-21R was detected by RT-qPCR and western blot analysis in GC cell lines. The association between IL-21R expression and clinicopathological characteristics and the prognosis of patients with GC was analyzed by immunohistochemistry and Kaplan-Meier plotter analysis. The biological functions of IL-21R were analyzed by a series of in vitro and in vivo experiments, and its regulation by ncRNAs was predicted by bioinformatics analysis and confirmed by luciferase assays and rescue experiments. As a result, the expression of IL-21R was found to be significantly increased in GC cell lines and tissues as compared with normal tissues, and was associated with tumor size and lymphatic metastasis, acting as an independent prognostic factor of poor survival and recurrence in patients with GC. The knockdown of IL-21R markedly suppressed GC cell proliferation and invasion, and IL-21R expression was further validated to be negatively regulated by miR-125a-3p (miR-125a). The overexpression of IL-21R reversed the tumor suppressive effects of miR-125a in vitro and in vivo. Moreover, lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acted as a sponge of miR-125a to modulate the IL-21R signaling pathway in GC cells and represented a risk factor for survival and recurrence in patients with GC. Taken together, the findings of this study reveal an oncogenic role for IL-21R in gastric tumorigenesis and verify that its activation is partly due to the dysregulation of the lncRNA MALAT1/miR-125a axis. These findings may provide a potential prognostic marker for patients with GC.

Cell-line-derived xenografts (CDXs) or patient-derived xenografts (PDXs) in immune-deficient mice have revolutionized our understanding of normal and malignant human hematopoiesis. Transgenic approaches further improved in vivo hematological research, allowing the development of human-cytokine-producing mice, which show superior human cell engraftment. The most popular mouse strains used in research, the NOG (NOD.Cg-Prkdc

T cells expressing CD19-specific chimeric Ag receptors (CARs) produce high remission rates in B cell lymphoma, but frequent disease recurrence and challenges in generating sufficient numbers of autologous CAR T cells necessitate the development of alternative therapeutic effectors. Vα24-invariant NKTs have intrinsic antitumor properties and are not alloreactive, allowing for off-the-shelf use of CAR-NKTs from healthy donors. We recently reported that CD62L

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal antigen expressed on multiple tumors and has no significant expression on normal human tissues. ROR1 is highly upregulated in chronic lymphocytic leukemia (CLL) B cells. NOD-scid IL2rg

A subset of hematologic cancer patients is refractory to treatment or suffers relapse, due in part to minimal residual disease, whereby some cancer cells survive treatment. Cell-adhesion-mediated drug resistance is an important mechanism, whereby cancer cells receive survival signals

Previous studies have proposed that epithelial to mesenchymal transition (EMT) in breast cancer cells regulates metastasis, stem cell properties and chemo-resistance; most studies were based on in vitro culture of cell lines and mouse transgenic cancer models. However, the identity and function of cells expressing EMT-associated genes in normal murine mammary gland homeostasis and human breast cancer still remains under debate. Using in vivo lineage tracing and triple negative breast cancer (TNBC) patient derived xenografts we demonstrate that the repopulating capacity in normal mammary epithelial cells and tumorigenic capacity in TNBC is independent of expression of EMT-associated genes. In breast cancer, while a subset of cells with epithelial and mesenchymal phenotypes have stem cell activity, in many cells that have lost epithelial characteristics with increased expression of mesenchymal genes, have decreased tumor-initiating capacity and plasticity. These findings have implications for the development of effective therapeutic agents targeting tumor-initiating cells.

Combining natural killer (NK) cell adoptive transfer with hypomethylating agents (HMAs) is an attractive therapeutic approach for patients with acute myeloid leukemia (AML). However, data regarding the impact of HMAs on NK cell functionality are mostly derived from in vitro studies with high nonclinical relevant drug concentrations. In the present study, we report a comparative study of azacitidine (AZA) and decitabine (DAC) in combination with allogeneic NK cells generated from CD34

MicroRNA-138 (miR-138) is a pro-survival oncomiR for glioma stem cells. In malignant gliomas, dysregulated expression of microRNAs, such as miR-138, promotes Tumour initiation and progression. Here, we identify the ancillary role of the CCAAT/enhancer binding protein β (C/EBPβ) as a transcriptional activator of miR-138. We demonstrate that a short 158 bp DNA sequence encoding the precursor of miR-138-2 is essential and sufficient for transcription of miR-138. This short sequence includes the A-box and B-box elements characteristic of RNA Polymerase III (Pol III) promoters, and is also directly bound by C/EBPβ via an embedded 'C/EBPβ responsive element' (CRE). CRE and the Pol III B-box element overlap, suggesting that C/EBPβ and transcription factor 3C (TFIIIC) interact at the miR-138-2 locus. We propose that this interaction is essential for the recruitment of the RNA Pol III initiation complex and associated transcription of the oncomiR, miR-138 in malignant gliomas.

Breast cancer is a major cause of cancer-related death in women. Antitumor T cell responses play critical therapeutic roles, including direct cytotoxicity mediated by CD8

The role and significance of interleukin (IL)-21 in the development of sporadic CRC have not been well defined. The aim of this study is therefore to investigate the dynamics of the IL-21 along colorectal adenoma-carcinoma sequence and to evaluate the impact of IL-21 on clinicopathological parameters and CRC prognosis. The real-time PCR results showed that the level of IL-21 in adenomas (n=50) and sporadic CRC (n=50) were significantly higher than that in normal controls (n=18), which were predominately observed in the adenoma/CRC stroma. Analysis revealed that IL-21 level was correlated with the overall survival time in CRC patients. Double immunofluorescence observations confirmed that IL-21 positive cells were mostly natural killer cells and T lymphocytes in the tumor stroma. These results indicate that significant increased IL-21 expression present within the adenoma/CRC microenvironment might have a potential predicating significance for survival time in patients with CRC.

Natural killer (NK) cells are capable of rapidly recognizing and efficiently killing tumor cells. This makes them a potentially promising agent for cancer immunotherapy. Additional genetic modifications of NK cells may further improve their anti-tumor efficacy. Numerous technical challenges associated with gene delivery into NK cells have significantly tempered this approach. We achieved efficient retroviral vector transduction of primary human NK cells that were stimulated by a combination of IL-2 and engineered K562 cells expressing membrane-bound IL-21. The activated NK cells were in less differentiated state and expressed NK cell activation receptors NKG2D, NKp30, CD16, and were highly HLA-DR-positive. This NK cell population was highly susceptible to the transduction by both GFP- and NGFR-expressing retroviral vectors, with transduction efficiency exceeding 50%. More mature CD57

Diffuse large B-cell lymphoma (DLBCL), the most common type of malignant lymphoma, accounts for 30% of adult non-Hodgkin lymphomas. Epstein-Barr virus (EBV) -positive DLBCL of the elderly is a newly recognized subtype that accounts for 8-10% of DLBCLs in Asian countries, but is less common in Western populations. Five DLBCL-derived cell lines were employed to characterize patterns of EBV latent gene expression, as well as response to cytokines and chemotaxis. Interleukin-4 and interleukin-21 modified LMP1, EBNA1 and EBNA2 expression depending on cell phenotype and type of EBV latent programme (type I, II or III). These cytokines also affected CXCR4- or CCR7-mediated chemotaxis in two of the cell lines, Farage (type III) and Val (type II). Further, we investigated the effect of EBV by using dominant-negative EBV nuclear antigen 1(dnEBNA1) to eliminate EBV genomes. This resulted in decreased chemotaxis. By employing an alternative way to eliminate EBV genomes, Roscovitine, we show an increase of apoptosis in the EBV-positive lines. These results show that EBV plays an important role in EBV-positive DLBCL lines with regard to survival and chemotactic response. Our findings provide evidence for the impact of microenvironment on EBV-carrying DLBCL cells and might have therapeutic implications.

The therapeutic potential of CRISPR system has already been demonstrated in many instances and begun to overlap with the rapidly expanding field of cancer immunotherapy, especially on the production of genetically modified T cell receptor or chimeric antigen receptor (CAR) T cells. Efficient genomic disruption of multiple gene loci to generate universal donor cells, as well as potent effector T cells resistant to multiple inhibitory pathways such as PD-1 and CTLA4 is an attractive strategy for cell therapy. In this study, we accomplished rapid and efficient multiplex genomic editing, and re-directing T cells with antigen specific CAR via a one-shot CRISPR protocol by incorporation of multiple gRNAs in a CAR lentiviral vector. High efficient double knockout of endogenous TCR and HLA class I could be easily achieved to generate allogeneic universal CAR T cells. We also generated Fas-resistant universal CAR T cells by triple gene disruption. Simultaneous gene editing of four gene loci using the one-shot CRISPR protocol to generate allogeneic universal T cells deficient of both PD1 and CTLA-4 was also attempted.

In spite of newly emerging therapies and the improved survival of patients with non-Hodgkin lymphoma (NHL), relapses or primary refractory disease are commonly observed and associated with dismal prognosis. Although discovery of the anti-CD20 antibody rituximab has markedly improved outcomes in B-cell NHL, rituximab resistance remains an important obstacle to successful treatment of these tumors. To improve the efficacy of CD20-targeted therapy, we fused interleukin 21 (IL-21), which induces direct lymphoma cytotoxicity and activates immune effector cells, to the anti-CD20 antibody (αCD20-IL-21 fusokine). We observed substantially enhanced IL-21R-mediated signaling by the fusokine compared with native IL-21 at equimolar concentrations. Fusokine treatment led to direct apoptosis of lymphoma cell lines and primary tumors that otherwise were resistant to native IL-21 treatment. In addition to direct cytotoxicity, the fusokine enhanced NK cell activation, effector functions, and interferon γ production, resulting in greater antibody-dependent cell-mediated cytotoxicity compared with IL-21 and/or anti-CD20 antibody treatments. Further, the αCD20-IL-21 fusokine stabilizes IL-21 and prolongs its half-life. In vivo αCD20-IL-21 therapy resulted in a significant tumor control in the rituximab-resistant A20-huCD20 tumors. Collectively, the dual functional ability of the αCD20-IL-21 fusokine to induce direct apoptosis and activate immune effector cells may provide benefit over existing treatments for NHL.

Bone marrow monocytes are primarily committed to osteoclast formation. It is, however, unknown whether potential primary alterations are specifically present in bone marrow monocytes from patients with multiple myeloma, smoldering myeloma or monoclonal gammopathy of undetermined significance. We analyzed the immunophenotypic and transcriptional profiles of bone marrow CD14

There is currently a paucity of preclinical models available to study the metastatic process in esophageal cancer. Here we report FLO-1, and its isogenic derivative FLO-1LM, as two spontaneously metastatic cell line models of human esophageal adenocarcinoma. We show that FLO-1 has undergone epithelial-mesenchymal transition and metastasizes following subcutaneous injection in mice. FLO-1LM, derived from a FLO-1 liver metastasis, has markedly enhanced proliferative, clonogenic, anti-apoptotic, invasive, immune-tolerant and metastatic potential. Genome-wide RNAseq profiling revealed a significant enrichment of metastasis-related pathways in FLO-1LM cells. Moreover, CDH1, which encodes the adhesion molecule E-cadherin, was the most significantly downregulated gene in FLO-1LM compared to FLO-1. Consistent with this, repression of E-cadherin expression in FLO-1 cells resulted in increased metastatic activity. Importantly, reduced E-cadherin expression is commonly reported in esophageal adenocarcinoma and independently predicts poor patient survival. Collectively, these findings highlight the biological importance of E-cadherin activity in the pathogenesis of metastatic esophageal adenocarcinoma and validate the utility of FLO-1 parental and FLO-1LM cells as preclinical models of metastasis in this disease.

Systemic mastocytosis are rare neoplasms characterized by accumulation of mast cells in at least one internal organ. The majority of systemic mastocytosis patients carry KIT D816V mutation, which activates constitutively the KIT receptor. Patient with advanced forms of systemic mastocytosis, such as aggressive systemic mastocytosis or mast cell leukemia, are poorly treated to date. Unfortunately, the lack of in vivo models reflecting KIT D816V+ advanced disease hampers pathophysiological studies and preclinical development of new therapies for such patients. Here, we describe a new in vivo model of KIT D816V+ advanced systemic mastocytosis developed by transplantation of the human ROSAKIT D816V-Gluc mast cell line in NOD-SCID IL-2R γ-/- mice, using Gaussia princeps luciferase as a reporter. Intravenous injection of ROSAKIT D816V-Gluc cells led, in 4 weeks, to engraftment in all injected primary recipient mice. Engrafted cells were found at high levels in bone marrow, and at lower levels in spleen, liver and peripheral blood. Disease progression was easily monitored by repeated quantification of Gaussia princeps luciferase activity in peripheral blood. This quantification evidenced a linear relationship between the number of cells injected and the neoplastic mast cell burden in mice. Interestingly, the secondary transplantation of ROSAKIT D816V-Gluc cells increased their engraftment capability. To conclude, this new in vivo model mimics at the best the features of human KIT D816V+ advanced systemic mastocytosis. In addition, it is a unique and convenient tool to study the kinetics of the disease and the potential in vivo activity of new drugs targeting neoplastic mast cells.

Human endogenous retrovirus type K (HERV-K) Env protein was previously demonstrated to be overexpressed in human breast cancer (BC) cells and tissues. However, the molecular pathways driving the specific alterations are unknown. We now show that knockdown of its expression with an shRNA (shRNAenv) blocked BC cell proliferation, migration, and invasion. shRNAenv transduction also attenuated the ability of BC cells to form tumors, and notably prevented metastasis. Mechanistically, downregulation of HERV-K blocked expression of tumor-associated genes that included Ras, p-RSK, and p-ERK. The major upstream regulators influenced by HERV-K knockdown were p53, TGF- β1, and MYC. Of interest, when the HERV-K env gene was overexpressed in shRNAenv-transduced BC cells using an HERV-K env expression vector, Ras/Raf/MEK/ERK pathway signaling was restored. CDK5, which alters p53 phosphorylation in some cancers, was upregulated and p53 was downregulated when HERV-K was overexpressed. CDK5 is also a mediator of TGF-β1-induced epithelial-mesenchymal transition and migration in cancer cells, and is involved in tumor formation. Importantly, reductions in migration, invasion, and transformation of BC cells stably transduced with shRNAenv was reversed after adding back a vector with a synonymous mutation of HERV-K env. Taken together, these results indicate that HERV-K Env protein plays an important role in tumorigenesis and metastasis of BC.

PURPOSE: Leukemia stem cells (LSC), which are insensitive to tyrosine kinase inhibitors (TKI), are an important source of TKI resistance and disease relapse in chronic myelogenous leukemia (CML). Obstacles to eradicating LSCs include limited understanding of the regulation network of LSCs. The current study aimed to examine the interplay between NF-κB and FOXM1/β-catenin, and the effect of its chemical intervention on CML LSCs.
EXPERIMENTAL DESIGN: The interplay between NF-κB and FOXM1/β-catenin was analyzed by reciprocal coimmunoprecipitation (co-IP) and chromatin immunoprecipitation (ChIP) assay in CML cells. The effect of disturbing NF-κB and FOXM1/β-catenin by niclosamide on the self-renewal capacity and survival of LSCs was evaluated in vitro in human primary CML CD34
RESULTS: Reciprocal co-IP experiments showed physical interaction of p65 and FOXM1. p65 promoted transcription of FOXM1 gene. ChIP assay revealed recruitment of p65 on the promoter of FOXM1 gene. Conversely, FOXM1 and β-catenin positively regulated the nuclear translocation and transcriptional activity of NF-κB in CML cells. Niclosamide disrupted the positive feedback loop between NF-κB and FOXM1/β-catenin, thereby impairing the self-renewal capacity and survival of CML LSCs. Niclosamide decreased the long-term engraftment of human CML LSCs in NOD-SCID IL2Rγ chain-deficient (NOG) mice, and prolonged the survival of CML mice.
CONCLUSIONS: Interaction of p65 with FOXM1/β-catenin is critical in CML and its disruption by niclosamide eradicates LSCs. These findings may improve the understanding of a self-renewal regulatory mechanism of LSCs and offer a rationale-based approach to eliminate LSCs in CML. Clin Cancer Res; 23(3); 789-803. ©2016 AACR.

Preclinical murine models of chimeric antigen receptor (CAR) T cell therapy are widely applied, but are greatly limited by their inability to model the complex human tumor microenvironment and adequately predict safety and efficacy in patients. We therefore sought to develop a system that would enable us to evaluate CAR T cell therapies in dogs with spontaneous cancers. We developed an expansion methodology that yields large numbers of canine T cells from normal or lymphoma-diseased dogs. mRNA electroporation was utilized to express a first-generation canine CD20-specific CAR in expanded T cells. The canine CD20 (cCD20) CAR expression was efficient and transient, and electroporated T cells exhibited antigen-specific interferon-gamma (IFN-γ) secretion and lysed cCD20+ targets. In a first-in-canine study, autologous cCD20-ζ CAR T cells were administered to a dog with relapsed B cell lymphoma. Treatment was well tolerated and led to a modest, but transient, antitumor activity, suggesting that stable CAR expression will be necessary for durable clinical remissions. Our study establishes the methodologies necessary to evaluate CAR T cell therapy in dogs with spontaneous malignancies and lays the foundation for use of outbred canine cancer patients to evaluate the safety and efficacy of next-generation CAR therapies and their optimization prior to translation into humans.

The immunomodulatory drug lenalidomide has demonstrated efficacy in patients with chronic lymphocytic leukemia (CLL), despite a lack of direct cytotoxic effects in vitro The mechanism of lenalidomide efficacy in vivo is thought to occur via a combination of enhanced immune activity and an alteration of tumor cell-microenvironment interactions. We demonstrate in whole blood from patients with CLL that lenalidomide significantly depletes malignant B cells. Lenalidomide also induced production of interleukin-21 (IL21) and its mRNA in T cells from patients with CLL. In addition, lenalidomide enhanced upregulation of functional IL21 receptor (IL21R) on the cell surface and increased receptor mRNA in vitro The in vitro combination of IL21 and lenalidomide enhanced IL21-mediated cytotoxicity toward CLL cells through a variety of mechanisms. We show association of cell death with upregulation of Bid by IL21, enhanced upregulation of Bid by the combination therapy, and diminished Lck and downstream BCR signaling activation of Syk and PLCG2. Collectively, we demonstrated an immune cell-tumor cell interaction through lenalidomide-mediated induction of IL21 and IL21R, with enhanced IL21-mediated cytotoxicity, which provides justification for this combination in clinical trials for patients with CLL. Cancer Immunol Res; 4(8); 698-707. ©2016 AACR.

Cholangiocarcinoma is a highly lethal cancer with limited therapeutic options. Recent genomic analysis of cholangiocarcinoma has revealed the presence of fibroblast growth factor receptor 2 (FGFR2) fusion proteins in up to 13% of intrahepatic cholangiocarcinoma (iCCA). FGFR fusions have been identified as a novel oncogenic and druggable target in a number of cancers. In this study, we established a novel cholangiocarcinoma patient derived xenograft (PDX) mouse model bearing an FGFR2-CCDC6 fusion protein from a metastatic lung nodule of an iCCA patient. Using this PDX model, we confirmed the ability of the FGFR inhibitors, ponatinib, dovitinib and BGJ398, to modulate FGFR signaling, inhibit cell proliferation and induce cell apoptosis in cholangiocarcinoma tumors harboring FGFR2 fusions. In addition, BGJ398 appeared to be superior in potency to ponatinib and dovitinib in this model. Our findings provide a strong rationale for the investigation of FGFR inhibitors, particularly BGJ398, as a therapeutic option for cholangiocarcinoma patients harboring FGFR2 fusions.

Cutaneous T-cell lymphoma (CTCL) is characterized by proliferation of malignant T cells in a chronic inflammatory environment. With disease progression, bacteria colonize the compromised skin barrier and half of CTCL patients die of infection rather than from direct organ involvement by the malignancy. Clinical data indicate that bacteria play a direct role in disease progression, but little is known about the mechanisms involved. Here, we demonstrate that bacterial isolates containing staphylococcal enterotoxin A (SEA) from the affected skin of CTCL patients, as well as recombinant SEA, stimulate activation of signal transducer and activator of transcription 3 (STAT3) and upregulation of interleukin (IL)-17 in immortalized and primary patient-derived malignant and nonmalignant T cells. Importantly, SEA induces STAT3 activation and IL-17 expression in malignant T cells when cocultured with nonmalignant T cells, indicating an indirect mode of action. In accordance, malignant T cells expressing an SEA-nonresponsive T-cell receptor variable region β chain are nonresponsive to SEA in monoculture but display strong STAT3 activation and IL-17 expression in cocultures with SEA-responsive nonmalignant T cells. The response is induced via IL-2 receptor common γ chain cytokines and a Janus kinase 3 (JAK3)-dependent pathway in malignant T cells, and blocked by tofacitinib, a clinical-grade JAK3 inhibitor. In conclusion, we demonstrate that SEA induces cell cross talk-dependent activation of STAT3 and expression of IL-17 in malignant T cells, suggesting a mechanism whereby SEA-producing bacteria promote activation of an established oncogenic pathway previously implicated in carcinogenesis.

RNA-binding proteins (RBPs) are increasingly identified as post-transcriptional drivers of cancer progression. The RBP LARP1 is an mRNA stability regulator, and elevated expression of the protein in hepatocellular and lung cancers is correlated with adverse prognosis. LARP1 associates with an mRNA interactome that is enriched for oncogenic transcripts. Here we explore the role of LARP1 in epithelial ovarian cancer, a disease characterized by the rapid acquisition of resistance to chemotherapy through the induction of pro-survival signalling. We show, using ovarian cell lines and xenografts, that LARP1 is required for cancer cell survival and chemotherapy resistance. LARP1 promotes tumour formation in vivo and maintains cancer stem cell-like populations. Using transcriptomic analysis following LARP1 knockdown, cross-referenced against the LARP1 interactome, we identify BCL2 and BIK as LARP1 mRNA targets. We demonstrate that, through an interaction with the 3' untranslated regions (3' UTRs) of BCL2 and BIK, LARP1 stabilizes BCL2 but destabilizes BIK with the net effect of resisting apoptosis. Together, our data indicate that by differentially regulating the stability of a selection of mRNAs, LARP1 promotes ovarian cancer progression and chemotherapy resistance.

Recurrent somatic mutations of the epigenetic modifier and tumor suppressor ASXL1 are common in myeloid malignancies, including chronic myeloid leukemia (CML), and are associated with poor clinical outcome. CRISPR/Cas9 has recently emerged as a powerful and versatile genome editing tool for genome engineering in various species. We have used the CRISPR/Cas9 system to correct the ASXL1 homozygous nonsense mutation present in the CML cell line KBM5, which lacks ASXL1 protein expression. CRISPR/Cas9-mediated ASXL1 homozygous correction resulted in protein re-expression with restored normal function, including down-regulation of Polycomb repressive complex 2 target genes. Significantly reduced cell growth and increased myeloid differentiation were observed in ASXL1 mutation-corrected cells, providing new insights into the role of ASXL1 in human myeloid cell differentiation. Mice xenografted with mutation-corrected KBM5 cells showed significantly longer survival than uncorrected xenografts. These results show that the sole correction of a driver mutation in leukemia cells increases survival in vivo in mice. This study provides proof-of-concept for driver gene mutation correction via CRISPR/Cas9 technology in human leukemia cells and presents a strategy to illuminate the impact of oncogenic mutations on cellular function and survival.

BACKGROUND: Diffuse large B cell lymphoma (DLBCL) is the most common type of lymphoid malignancy worldwide. Approximately 5 % of cases of DLBCL are so-called double-hit lymphomas (DHL), defined by a chromosomal translocation or rearrangement involving MYC/8q24.2 in combination with another recurrent breakpoint, usually BCL2/18q21.3. Patients with MYC/BCL2 DHL are resistant to standard front-line therapy, and currently, there is no consensus for a therapeutic strategy to treat these patients. Lack of clinically relevant or validated human experimental DHL models of any type that would improve our understanding of the biologic basis of MYC/BCL2 DHL pathophysiology continues to hamper identification of valid therapeutic targets. We describe a unique MYC/BCL2 DHL cell line with morphologic features of DLBCL that we have established, designated as RC.
METHODS: We used tissue culture techniques to establish the RC cell line from primary DLBCL cells. We also utilized molecular and cellular biological techniques including flow cytometry, polymerase chain reaction (PCR), DNA fingerprinting, reverse-phase protein array, conventional cytogenetics, and fluorescence in situ hybridization (FISH) analysis to characterize the RC cell line. NSG-severe combined immunodeficiency (SCID) mice were utilized as a model for xeno-transplantation of RC cells.
RESULTS: RC cells had the following immunophenotype: positive for CD10, CD19, CD20, CD22, CD38, CD43, CD44, and CD79b and negative for CD3, CD4, CD5, CD8, CD11c, CD14, CD30, CD56, and CD200, which was identical to the primary tumor cells. Conventional cytogenetic analysis showed a t(2;8)(p12;q24.2) and t(14;18)(q32;q21.3), corresponding to MYC and BCL2 gene rearrangements, respectively. DNA fingerprinting authenticated the RC cell line to be of the same clone as the primary tumor cells. In addition, RC cells were established in SCID mice as an in vivo model for translational therapeutics studies. Proteomic analysis showed activation of the mTOR signaling pathway in RC cells that can be targeted with an mTOR inhibitor.
CONCLUSION: The data presented confirm the validity of the RC cell line as a representative model of MYC/BCL2 DHL that will be useful for both in vitro and in vivo studies of DHL pathogenesis and therapeutics.

Cancer stem cells (CSCs) play major roles in cancer initiation, progression, and metastasis. It is evident from growing reports that PI3K/Akt/mTOR and Sonic Hedgehog (Shh) signaling pathways are aberrantly reactivated in pancreatic CSCs. Here, we examined the efficacy of combining NVP-LDE-225 (PI3K/mTOR inhibitor) and NVP-BEZ-235 (Smoothened inhibitor) on pancreatic CSCs characteristics, microRNA regulatory network, and tumor growth. NVP-LDE-225 co-operated with NVP-BEZ-235 in inhibiting pancreatic CSC's characteristics and tumor growth in mice by acting at the level of Gli. Combination of NVP-LDE-225 and NVP-BEZ-235 inhibited self-renewal capacity of CSCs by suppressing the expression of pluripotency maintaining factors Nanog, Oct-4, Sox-2 and c-Myc, and transcription of Gli. NVP-LDE-225 co-operated with NVP-BEZ-235 to inhibit Lin28/Let7a/Kras axis in pancreatic CSCs. Furthermore, a superior interaction of these drugs was observed on spheroid formation by pancreatic CSCs isolated from Pankras/p53 mice. The combination of these drugs also showed superior effects on the expression of proteins involved in cell proliferation, survival and apoptosis. In addition, NVP-LDE-225 co-operated with NVP-BEZ-235 in inhibiting EMT through modulation of cadherin, vimentin and transcription factors Snail, Slug and Zeb1. In conclusion, these data suggest that the combined inhibition of PI3K/Akt/mTOR and Shh pathways may be beneficial for the treatment of pancreatic cancer.