Development Of Lymphoid Neoplasms Research Articles

Influence of Age on Leukemia Mortality Associated with Exposure to γ rays and 2-MeV Fast Neutrons in Male C3H Mice.

The relative biological effectiveness (RBE) of densely ionizing radiation can depend on the biological context. From a radiological perspective, age is an important factor affecting health risks of radiation exposure, but little is known about the modifying impact of age on the effects of densely ionizing radiation. Herein, we addressed the influence of age on leukemogenesis induced by accelerator-generated fast neutrons (mean energy, ∼2 MeV). Male C3H/HeNrs mice were exposed to 137Cs γ rays (0.2-3.0 Gy) or neutrons (0.0485-0.97 Gy, γ ray contamination 0.0105-0.21 Gy) at 1, 3, 8, or 35 weeks of age and observed over their lifetimes under specific pathogen-free conditions. Leukemia and lymphoma were diagnosed pathologically. Hazard ratio (HR) and RBE for myeloid leukemia mortality as well as the age dependence of these two parameters were modeled and analyzed using Cox regression. Neutron exposure increased HR concordant with a linear dose response. The increase of HR per dose depended on age at exposure, with no significant dose dependence at age 1 or 3 weeks but a significant increase in HR of 5.5 per Gy (γ rays) and 16 per Gy (neutrons) at 8 weeks and 5.8 per Gy (γ rays) and 9 per Gy (neutrons) at 35 weeks. The RBE of neutrons was 2.1 (95% confidence interval, 1.1-3.7), with no dependence on age. The development of lymphoid neoplasms was not related to radiation exposure. The observed increasing trend of radiation-associated mortality of myeloid leukemia with age at exposure supports previous epidemiological and experimental findings. The results also suggest that exposure at the susceptible age of 8 or 35 weeks does not significantly influence the RBE value for neutrons for induction of leukemia, unlike what has been documented for breast and brain tumors.

Genetic predisposition to myelodysplastic syndrome/leukemia

The development of gene analysis in cancer is remarkable, and understanding of molecular pathology has been elucidated. Somatic mutations, that is, genetic analysis in cancer cells, have contributed to the accurate diagnosis of tumors, prognostic prediction, and detection of therapeutic targets. In contrast, germline mutations have been identified as the cause of hereditary diseases. In the past, symptom diagnosis was the main focus for hereditary diseases. However, genetic information has greatly contributed to its definitive diagnosis. For hematopoietic malignancies, the 2016 revision of the World Health Organization classification newly proposed a section on myeloid neoplasms with germline predisposition. Genetic predispositions characterized by the development of lymphoid neoplasms and solid tumors have also been reported. Since 2016, new findings such as SAMD9/9L mutation have been discovered. This chapter outlines the typical genetic predisposition to myelodysplastic syndrome/leukemia.

Emerging Roles for the Gut Microbiome in Lymphoid Neoplasms.

Lymphoid neoplasms encompass a heterogeneous group of malignancies with a predilection for immunocompromised individuals, and the disease burden of lymphoid neoplasms has been rising globally over the last decade. At the same time, mounting studies delineated a crucial role of the gut microbiome in the aetiopathogenesis of various diseases. Orchestrated interactions between myriad microorganisms and the gastrointestinal mucosa establish a defensive barrier for a range of physiological processes, especially immunity and metabolism. These findings provide new perspectives to harness our knowledge of the gut microbiota for preclinical and clinical studies of lymphoma. Here, we review recent findings that support a role for the gut microbiota in the development of lymphoid neoplasms and pinpoint relevant molecular mechanisms. Accordingly, we propose the microbiota-gut-lymphoma axis as a promising target for clinical translation, including auxiliary diagnosis, novel prevention and treatment strategies, and predicting clinical outcomes and treatment-related adverse effects of the disease in the future. This review will reveal a fascinating avenue of research in the microbiota-mediated lymphoma field.

PS1122 RECURRENT XPO1 MUTATIONS IDENTIFIED AS PREDICTIVE MARKER FOR ADVANCED CLL PROGRESSION

Background:Exportin 1 (XPO1/CRM1) is responsible for nuclear‐to‐cytosol export of RNAs and protein cargos, including various tumor suppressors (e.g. p53, IκB) and growth regulators (e.g. RB, p21). Our previous work has shown that XPO1 is upregulated in chronic lymphocytic leukemia (CLL), leading to mislocalization of critical cargos, which may contribute to activation of pathways involved in leukemogenesis and disease progression. Whole exome sequencing has revealed recurrent mutations to a highly conserved amino acid (E571G/E571K) near the XPO1 cargo binding groove in ∼5% of CLL cases and in ∼25% of CLL patients that develop a clinical complication of their disease with a very abysmal prognosis known as Richter's transformation. Despite inherent association with advanced hematologic malignancies, conflicting reports describe the merit of XPO1 mutations as a predictive marker for poor clinical outcome in CLL.Aims:We aimed to assess the significance of recurrent XPO1 E571 mutations on CLL progression and overall outcome by concurrent analysis of a human CLL clinical cohort and a large scale evaluation of a novel XPO1 transgenic mouse model.Methods:Retrospective analysis of an independent sample set of CLL cases (N = 466) was used to correlate XPO1 mutation status (N = 18, >30% clonal population CLL cells) with clinical data. These included time to first treatment, overall survival, IgHV mutation status, ZAP‐70 expression (%), and status of epigenetic programming. Differential gene expression analysis in newly diagnosed untreated CLL patient lymphocytes was constructed from RNA‐sequencing, with downstream pathway analysis performed by Ingenuity Pathway Analysis software. A novel XPO1 transgenic mouse model (Eμ‐XPO1) was developed with human XPO1 (WT/G/K) gene under the heavy chain promoter/enhancer of the B cell expression, and was then crossed with the Eμ‐TCL1 mouse to assess contribution of XPO1 mutations in concordance with murine CLL. Disease onset and progression was determined via flow cytometry (% CD19/CD5 double positive cells) analysis of peripheral blood.Results:In the CLL cohort we analyzed, presence of XPO1 E571 mutations (18/466, 4%) confers disease characteristics consistent with poor clinical prognosis; including association with low epigenetic programming (18/18), unmutated IgHV region (17/17), elevated ZAP‐70 expression (p = 0.012), and reduction in treatment free progression (p = 0.002) and overall survival (p = 0.068) compared with XPO1 un‐mutated CLL. Similarly, overexpression of E571WT, K or G as the sole genetic abnormality (Eμ‐XPO1) resulted in the development of lymphoid neoplasms at advanced ages (>20 mo) compared to age‐matched B6 mice. Furthermore, overexpression of E571G (N = 174, p = 0.001) and E571K (N = 188, p = 0.093), but not E571WT (N = 151, p = 0.713) XPO1 showed a trend of accelerated disease onset in the Eμ‐XPO1xTCL1 model consistent with a role of mutant XPO1 in disease progression. Lastly, RNA‐seq in XPO1 E571 or wild‐type CLL cells revealed unique clustering of differentially expressed genes specific to lymphocyte activation, signaling, and regulation, suggesting amplification of pro‐survival and anti‐apoptotic intracellular pathways.Summary/Conclusion:We report evidence for XPO1 E571 mutations as a predictive marker for poor CLL clinical prognosis warranting further investigation for selective targeting of mutated XPO1 as a personalized cancer therapy in CLL.

Female reproductive factors and risk of lymphoid neoplasm: The Japan Public Health Center-based Prospective Study.

Although a possible role of reproductive factors in lymphomagenesis has been hypothesized, results of epidemiological studies have been inconsistent. Here, we investigated the association between reproductive factors and the risk of lymphoid neoplasm and its subgroups. We used data from a large‐scale, population‐based prospective study in a Japanese cohort with 42 691 eligible women aged 40‐69 years from 1990 to 1994. During a mean follow up of 18.7 years, we identified 176 cases of lymphoid neoplasm and 90 of non‐Hodgkin lymphoma (NHL). A multivariable‐adjusted Cox proportional hazards regression model was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for the risk of lymphoid neoplasms and its subgroups according to self‐reported reproductive factors. Parous women had an increased risk of lymphoid neoplasm compared with nulliparous women (HR = 2.51, 95% CI, 1.03‐6.13). An increased risk of lymphoid neoplasms was found in women with later onset of menarche (≤13 years old; reference: 14‐15; HR = 1.75, 95% CI = 1.10‐2.79: ≥16; HR = 1.93, 95% CI = 1.17‐3.19: P‐trend: 0.01) and a shorter menstrual cycle (28‐29 days; reference: ≤27; HR = 1.60, 95% CI = 1.05‐2.43, P‐trend = 0.81). No association was observed between lymphoid neoplasms and other reproductive factors, including age at first birth, breastfeeding, type of menopause, or exogenous hormone use. Our study suggests that ever parity, late age at menarche and a short menstrual cycle length may be associated with the development of lymphoid neoplasms. The inconsistency seen in epidemiological research to date warrants further investigation.

Temporal and Spatially Regulated Oncogenic KIT Expression and Loss of Dnmt3a Cooperate to Drive MPN Development: Role of PI3Kinase in Dnmt3a Loss Induced Hyperproliferation in Myeloid Cells

Recent studies, including studies from our group have shown that somatic mutations in DNA methyltransferase type 3A (DNMT3A) are frequently associated with systemic mastocytosis (SM), myelodysplastic syndrome and AML. Importantly, the presence of this mutation is associated with poor prognosis and overall patient survival. We have shown that approximately 12% of patients with SM possess DNMT3A mutations, which are commonly co-expressed with an activating mutation of KIT (KITD816V in humans and KITD814V in mice). However, it is unclear how DNMT3A mutations contribute to myeloid lineage derived mast cell growth and differentiation either alone or in conjunction with KITD816V. Further, the mechanisms by which loss of DNMT3A impairs various mast cell functions either alone or in cooperation with KITD816V are poorly understood. Utilizing mice conditionally deficient in Dnmt3a in the hematopoietic compartment, we show that loss of Dnmt3a in vivo results in increased numbers of mast cells relative to controls. In vitro, loss of Dnmt3a results in accelerated and enhanced differentiation of mast cells from its bone marrow (BM) precursors. Previous studies have shown that the level of expression of the transcription factor, Microthalamia (MITF) (high MITF expression drives mast cell commitment) and CEBPα (high C/EBPα drives basophil commitment) in Basophil-Mast cell common progenitor (BMPs) drives the fate of these cells towards either basophilic lineage or mast cell lineage. To assess why loss of Dnmt3a results in increased mast cell lineage commitment, we performed RNAseq analysis and found elevated expression of MITF and a profound repression in the expression of C/EBPα in BM precursors. Importantly, restoring the expression of Dnmt3a in Dnmt3a deficient BM cells, completely restored enhanced differentiation, along with the expression of MITF and C/EBPα. To our surprise, no appreciable differences in the expression of Gata-1, Gata-2 or PU.1 were noted in the absence of Dnmt3a relative to controls. These results demonstrate that early loss of C/EBPα in Dnmt3a null cells contributes to enhanced maturation of mast cells from their precursors. We next assessed the growth and survival potential of Dnmt3a mast cells and found a significant increase in SCF-mediated growth of these cells compared to controls. Biochemical analysis revealed greater PI3Kinase activation in Dnmt3a null cells, and these findings were supported by genome wide transcriptome analysis involving Ingenuity pathway analysis (IPA) and Gene set enrichment analysis (GSEA). Importantly, mast cells derived from Dnmt3a null BM lacking the expression of p85α regulatory subunit of PI3Kinase (Dnmt3a-/-:p85α-/-) or pharmacologic inhibition of PI3Kinase completely corrected SCF induced hyper proliferation in these cells to near normal levels. The increase in PI3Kinase activity in Dnmt3a null cells was associated with the loss of PTEN expression. To understand how loss of Dnmt3a and expression of an oncogenic form of KIT cooperate to drive MPN, we generated mice in which the expression of oncogenic KIT was temporally and spatially regulated in a cell type and tissue specific manner using the Mx-Cre system along with the expression of Dnmt3a. Consistent with earlier studies, we observed that KitD814V/+ mutation alone only resulted in the development of lymphoid neoplasms. In contrast, Dnmt3a-/- :KitD814V/+ mice manifested robust signs of MPN development including splenomegaly with increased numbers of neutrophils and monocytes in the peripheral blood associated with a significant reduction in lymphoid cells including B cells. Importantly, we noted a 5-fold increase in the fraction of LSKs and GMPs in the BM of Dnmt3a-/- :KitD814V/+ mice compared to controls and consequently an increase in the presence of mature Gr-1 and Mac-1 positive myeloid cells in the BM, spleen and in the PB of these mice relative to controls. The observed MPN was more aggressive in Dnmt3a-/- :KitD814V/+ mice compared to Dnmt3a+/- :KitD814V/+ mice and of stem cell origin as transplantation of BM cells from these mice recapitulated the development of MPN in recipient mice, similar to that observed in the original animals. The impact of PI3Kinase inhibition on mitigating oncogenic KIT and loss of Dnmt3a induced MPN and overall survival will be discussed. DisclosuresNo relevant conflicts of interest to declare.

A Rare Case of Hodkin's Lymphoma of the Mediastinum Imitating Retrosternal Goiter - Retrospective Analysis of the Diagnostic Process

Primary extranodal sites of development of lymphoid neoplasms are rare and concern about 5% of patients with Hodgkin's lymphoma. Extranodal development is more common in non Hodgkin's lymphoma and may reach 33%. A 27-year-old woman was diagnosed by a cardiologist for a short breath. On the physical examination no other abnormalities were observed. Echocardiography, performed by cardiologist, revealed a large tumor, overlaying the right ventricle and compressing the pulmonary trunk. Chest X-ray, ultrasound and CT-scan confirmed diagnosis. In fine needle aspiration clear, lucid fluid was obtained. Scintygraphy of the neck and thorax showed accumulation of the marker in the properly placed but enlarged thyroid gland. Patient was qualified for surgical treatment - cervicotomy and sternothomy were performed. The histopatological exam of the tumor revealed Hodgkin's lymphoma of the mediastinum (classical subtype NS-1). Following the surgery, adjuvant therapy was instituted. After the treatment PET-CT-scan did not show any kind of non-physiological radiomarker's accumulation in the monitored regions of the body and in in three-years follow-up the patient shows no signs of recurrence.

Identification of Huntingtin Interacting Protein 1 Related (HIP1R) as a Novel Lymphoma Autoantigen Using Antigen Array Profiling

We screened lymphoma patients' serum samples against protein/antigen arrays, containing over 10,000 different human proteins, to identify disease-associated auto-IgG antibody interactions. This approach identified a humoral immune response to the HIP1R antigen in 40% of patients' sera (4/6 follicular lymphomas, 3/5 germinal centre [GC]-derived diffuse large B-cell lymphomas [DLBCL], 2/4 transformed DLBCL, 1/5 mantle cell lymphomas, 1/5 non-GC DLBCL and 1/5 peripheral T-cell lymphomas). HIP1R has also previously been identified as an autoantigen in colon cancer using the SEREX technique. HIP1R is one of two members of the Huntingtin interacting protein 1 family. Both HIP1R and HIP1 share significant sequence homology and are cytoplasmic proteins that interact with inositol lipids, clathrin and actin. Interestingly, both proteins can stabilize pools of receptor tyrosine kinases by inhibiting their trafficking to the lysosome for degradation, which may mediate affects on cell growth and transformation. HIP1 has been more extensively characterized in cancer and was originally implicated in hematological malignancy when it was identified as a platelet-derived growth factor β receptor fusion partner in chronic myelomonocytic leukemia. HIP1 expression is elevated in lymphomas and can be induced by activated NF-κB while transgenic overexpression of HIP1 is associated with the development of lymphoid neoplasms. Interestingly, the increased severity of a murine Hip1/Hip1r double-knockout phenotype indicates that Hip1r can partially functionally compensate for the loss of Hip1, suggesting they have overlapping roles in vivo. Autoantibodies to HIP1 have been reported in 59% of human lymphoma sera, compared to 31% of healthy controls and showed higher titre in patients who had undergone remission than those that relapsed (Bradley et al. 2007. Cancer Res 67:8923). However, the region of HIP1 tested for this serum reactivity shares high sequence homology with HIP1R, and thus this previous study is likely to have identified autoantibodies to both HIP1 and HIP1R. In contrast the region of HIP1R on our antigen array does not share homology with HIP1, suggesting that HIP1R expression is also altered in lymphomas. Quantitative RT-PCR was performed for both HIP1 and HIP1R on a panel of lymphoma cell lines, normal tissues and purified B- and T-cell populations. Overall HIP1R was more widely expressed and at higher levels than HIP1 in both normal lymphocytes and lymphoma cell lines. The particularly high level expression of HIP1R in Burkitt lymphoma cell lines and increased expression in GC- compared to non-GC DLBCL is consistent with the high frequency of autoantibodies in the sera from patients with GC-derived lymphomas. Two commercial monoclonal antibodies were successfully validated for the detection of HIP1R, although only the BD Transduction Laboratories' antibody is raised to a region that lacks any significant stretches of homology with HIP1. Western blotting experiments have confirmed the expression of the HIP1R protein in lymphoma cell lines and showed a good correlation with mRNA expression levels. The BD Transduction Laboratories anti-HIP1R antibody recognises a formalin resistant epitope and studies are already underway to elucidate HIP1R expression patterns in lymphoma biopsies.

Aberrant Huntingtin Interacting Protein 1 in Lymphoid Malignancies

Huntingtin interacting protein 1 (HIP1) is an inositol lipid, clathrin, and actin binding protein that is overexpressed in a variety of epithelial malignancies. Here, we report for the first time that HIP1 is elevated in non-Hodgkin's and Hodgkin's lymphomas and that patients with lymphoid malignancies frequently had anti-HIP1 antibodies in their serum. Moreover, p53-deficient mice with B-cell lymphomas were 13 times more likely to have anti-HIP1 antibodies in their serum than control mice. Furthermore, transgenic overexpression of HIP1 was associated with the development of lymphoid neoplasms. The HIP1 protein was induced by activation of the nuclear factor-kappaB pathway, which is frequently activated in lymphoid malignancies. These data identify HIP1 as a new marker of lymphoid malignancies that contributes to the transformation of lymphoid cells in vivo.

Mechanisms that contribute to the development of lymphoid malignancies: roles for genetic alterations and cytokine production.

Recent studies have defined genetic alterations commonly associated with transformed lymphocytes. This review suggests roles for these alterations in the development of lymphoid neoplasms. Damage to the genes encoding proteins that function in intracellular signaling, transcription, or regulation of the cell cycle has been identified and linked at varying degrees to the progression of certain lymphoid malignancies. An understanding of the mechanistic consequences following such genetic alterations is essential to an understanding of the development of these lymphoid neoplasms. In contrast, it is also becoming clear that the dysregulated expression of proteins that are not genetically altered can also contribute to the progression of lymphoid malignancies. One such example is the excessive expression of "normal" lymphokines of cytokines which accompanies many lymphoproliferative diseases. The dysregulated expression of cytokines during malignancy can result in the augmentation of growth of transformed lymphocytes, as well as an alteration of the anti-tumor immune response. The latter mechanism is especially important because evasion of the impending immune response is a prerequisite for the progression of lymphoproliferative diseases. Taken together, this review supports the notion that the development of lymphoid malignancies is multifactorial, involving genetic alterations as well as dysregulated cytokine expression.