Cruciform structures are a common DNA feature important for regulating biological processes

DNA cruciforms play an important role in the regulation of natural processes involving DNA. These structures are formed by inverted repeats, and their stability is enhanced by DNA supercoiling. Cruciform structures are fundamentally important for a wide range of biological processes, including replication, regulation of gene expression, nucleosome structure and recombination. They also have been implicated in the evolution and development of diseases including cancer, Werner's syndrome and others

Nuclear Export in Non-Hodgkin Lymphoma and Implications for Targeted XPO1 Inhibitors

Exportin-1 (XPO1) is a key player in the nuclear export pathway and is overexpressed in almost all cancers. This is especially relevant for non-Hodgkin lymphoma (NHL), where high XPO1 expression is associated with poor prognosis due to its oncogenic role in exporting proteins and RNA that are involved in cancer progression and treatment resistance. Here, we discuss the proteins and RNA transcripts that have been identified as XPO1 cargo in NHL lymphoma including tumour suppressors, immune modulators, and transcription factors, and their implications for oncogenesis. We then highlight the research to date on XPO1 inhibitors such as selinexor and other selective inhibitors of nuclear export (SINEs), which are used to treat some cases of non-Hodgkin lymphoma. In vitro, in vivo, and clinical studies investigating the anti-cancer effects of SINEs from bench to bedside, both as a single agent and in combination, are also reported. Finally, we discuss the limitations of the current research landscape and future directions to better understand and improve the clinical utility of SINE compounds in NHL

Nuclear Export in Non-Hodgkin Lymphoma and Implications for Targeted XPO1 Inhibitors

Exportin-1 (XPO1) is a key player in the nuclear export pathway and is overexpressed in almost all cancers. This is especially relevant for non-Hodgkin lymphoma (NHL), where high XPO1 expression is associated with poor prognosis due to its oncogenic role in exporting proteins and RNA that are involved in cancer progression and treatment resistance. Here, we discuss the proteins and RNA transcripts that have been identified as XPO1 cargo in NHL lymphoma including tumour suppressors, immune modulators, and transcription factors, and their implications for oncogenesis. We then highlight the research to date on XPO1 inhibitors such as selinexor and other selective inhibitors of nuclear export (SINEs), which are used to treat some cases of non-Hodgkin lymphoma. In vitro, in vivo, and clinical studies investigating the anti-cancer effects of SINEs from bench to bedside, both as a single agent and in combination, are also reported. Finally, we discuss the limitations of the current research landscape and future directions to better understand and improve the clinical utility of SINE compounds in NHL.</jats:p

An Exploratory Study of Cytokine Markers of Cancer-Related Cognitive Impairment in Hematological Malignancy

Abstract Introduction. Cancer-related cognitive impairment is a distressing symptom that affects numerous patients after cancer therapy, including those treated for hematological malignancy. The lack of effective interventions has driven interest in determining underlying mechanisms. Accumulating evidence in the context of solid tumours suggests inflammatory processes are involved in the development of cognitive symptoms. The objective of this study was to explore whether changes in serum markers of inflammation underlie differences in cognitive functioning among patients treated for hematological malignancies. Methods. The sample comprised participants treated for lymphoma or multiple myeloma who were participating in a feasibility study of a computerized cognitive training program. Prior to the intervention, a battery of neuropsychological tests were administered to assess cognitive function in the following domains: Learning Efficiency and Memory; Information Processing and Psychomotor Efficiency; and Executive Functioning and Working Memory. Composite T-scores for each domain were computed as the mean of demographically adjusted T-scores from constituent tests. Blood was drawn concurrently from consenting participants. Soluble proteins were quantified from serum using a multiplex sandwich elisa assay of 27 arrayed cytokine and chemokine analytes. Pearson's correlations between composite T-scores and cytokine concentrations were calculated. T-tests assessed differences in cytokine concentrations between participants who met the criteria for impairment (composite T-score&lt;40) compared to those who did not. Results. Eleven participants (Non-Hodgkin Lymphoma: n=5; Hodgkin Lymphoma: n=3; Multiple Myeloma: n=3; Mean age = 52 years; 6 males/5 females) were included in this analysis. Six of the participants were treated with autologous stem cell transplant for either lymphoma or multiple myeloma; five with primary chemotherapy treatment for lymphoma. Participants were a median 59 days (range 28-265 days) from completion of treatment. Proportion of patients impaired in each domain were: Leaning Efficiency and Memory (5/11); Information Processing and Psychomotor Efficiency (5/11); and Executive Functioning and Working Memory (3/11). Serum concentration of Chemokine Ligand 4 (CCL4, also known as Macrophage Inflammatory Protein 1β) was positively correlated with performance in Information Processing and Psychomotor Efficiency, such that increased CCL4 was associated with better cognitive performance (r=0.62, p=0.0418). Participants who met the criteria for impairment in the domain of Information Processing and Psychomotor Efficiency had a significantly lower concentration of CCL4 compared to those who did not (impaired: 8.14 pg/ml; non-impaired: 14.88 pg/ml; p= 0.0072). Participants who met the criteria for impairment in the domain of Information Processing and Psychomotor Efficiency also had a lower concentration of Granulocyte Colony Stimulating Factor (GCSF) compared to those who did not (impaired: 14.40 pg/ml; non-impaired: 22.47 pg/ml; p=0.0467). We did not detect any other significant relationships between cytokine concentration and cognitive performance. Conclusions. The findings from this exploratory study suggest that there may be a role for macrophage recruitment in modulating the pathogenesis of cancer-related cognitive impairment in hematological malignancies, particularly in the area of information processing and psychomotor speed. Larger studies are needed to validate this finding and clarify the role of CCL4 in the context of cell signalling pathways involved in cognitive functioning. Disclosures Kuruvilla: Janssen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Leukemia and Lymphoma Society Canada: Research Funding; Abbvie: Consultancy; Celgene: Honoraria; Amgen: Honoraria; Gilead: Consultancy, Honoraria; Princess Margaret Cancer Foundation: Research Funding; Seattle Genetics: Consultancy, Honoraria; Karyopharm: Honoraria; Lundbeck: Honoraria; Roche: Consultancy, Honoraria, Research Funding. </jats:sec

Abstract 3604: Investigation of the role of CSF-1 and its receptor in the bone marrow stroma microenvironment in acute myeloid leukemia

Abstract Supporting cells in the bone marrow microenvironment are an essential source of growth factors and cytokines that drive both normal hematopoeisis and leukemogenesis. Acute myeloid leukemia (AML) is a heterogeneous and growth factor-dependent disease of the bone marrow. The human macrophage colony stimulating factor (M-CSF, CSF-1) is a cytokine produced by supporting cells in the bone marrow that promotes the differentiation and maturation of monocytes and macrophages from myeloid precursors. Since CSF-1 is an essential factor in myelopoeisis, it has important implications in AML, a disease characterized by the increased proliferation of immature myeloid blast cells. Moreover CSF-1 and CSF-1R are highly expressed in some AML cases, lending further support for their investigation. CSF-1 exists as a full-length secreted (variant 1 or v1) and membrane-bound (variant 3 or v3) isoform. The membrane-bound v3 isoform is the predominant form in the bone marrow. CSF-1 binds to the colony stimulating factor-1 receptor (CSF-1R), a class III receptor tyrosine kinase found on mononuclear phagocytes. CSF-1R activation leads to stimulation of survival, proliferation and differentiation pathways. In this study, the effects of the CSF-1/CSF-1R interaction were investigated in the context of the bone marrow microenvironment in an in-vitro co-culture system. In this model, human leukemic cells (patient samples and cell lines) were grown in co-culture with mouse stromal cells expressing human CSF-1. The cellular and molecular responses arising from the interaction between leukemic cells expressing CSF-1R and stromal cells producing CSF-1 were examined. AML cells cultured with CSF-1-expressing stroma displayed better long-term (2-5 weeks) growth and survival than cells cultured with non-CSF-1-expressing stroma. There was a 2-fold increase in the number of cells on CSF-1 v3 stroma compared to empty vector (ev) control stroma after 5 weeks of co-culture. AML cells were maintained on CSF-1 v3 stroma 1.5-1.75 fold longer than on ev stroma (survival in days). Co-culture of AML cells with CSF-1-expressing stroma led to a decrease in CSF-1R expression on the surface of AML cells, accompanied by an increase in CD34 and decrease in CD38 expression. CSF-1-expressing stroma led to increases in phosphorylation of Akt and p70S6K, effectors of the PI3k/Akt pathway, in AML cells. Analysis of cytokine production in AML-stromal cell co-cultures revealed an increase in the secretion of IL-3 and IL-6 from stromal cells and an increase in IL-8 and vascular endothelial growth factor (VEGF) from AML cells. These findings suggest that CSF-1 presented by stromal cells mediates the growth and survival of AML cells through changes in cell surface markers, molecular signaling effectors and cytokine secretion. This work has helped identify targets of interest that may be exploited for therapeutic purposes in AML-stromal cell interactions. Citation Format: Ayesha Rashid, Mohammed Fateen, Rhe Juan, Rob C. Laister, Mark Minden. Investigation of the role of CSF-1 and its receptor in the bone marrow stroma microenvironment in acute myeloid leukemia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3604. doi:10.1158/1538-7445.AM2014-3604</jats:p

Control of B lymphoma through regulation of TRAF protein degradation during nutrient stress (TUM7P.932)

Abstract The TNFR family of receptors includes members, such as CD40, that mediate important immune functions. TNFRs play critical roles in regulating cellular survival, where they utilize TNFR associated factors (TRAFs), including TRAF1 and TRAF2, as adaptors to signal through NF-κB and MAPK pathways. TRAF1 is linked with increased lymphoma cell survival and is overexpressed in over 50% of human lymphomas, with highest expression in most refractory B-CLL. Thus there is interest in blocking TRAF1 induced survival signaling in lymphoma. Here we show that during nutrient deprivation, induced by low glutamine in the media or by treatment with the licensed drug Erwinaze, TRAF1 is essential for maintaining protein levels of another pro-survival signaling adaptor, TRAF2, in RAJI cells (Burkitt's lymphoma). The PKC, PKN1, has been shown to phosphorylate TRAF1. Utilizing shRNA knockdown, we show that loss of PKN1 reduces TRAF1 expression, suggesting that PKN1 phosphorylation stabilizes TRAF1. Importantly, we demonstrated that Erwinaze treatment causes cell death in TRAF1 deficient RAJI cells but not in wild type cells. Moreover, PKN1 deficient RAJI cells, which exhibit lower TRAF1 expression, were also susceptible to treatment with Erwinaze. Together, these findings suggest that a combination therapy that targets TRAF1 for degradation (i.e. PKN1 inhibitor) along with Erwinaze to cause nutrient stress mediated loss of TRAF2 constitutes an effective and aggressive therapy for B cell lymphoma</jats:p

Small Molecule Stat5-Sh2 Domain Inhibitors Exhibit Potent Antileukemia Activity

We investigate the alignment of 4\u27-pentyl-4-cynobiphenyl (5CB) liquid crystal on phase-separated two-component organosilane monolayers that consist of the protruding islands surrounded by a continuous phase. The molecular disordering at the protruding island edge locally perturbs the homeotropic alignment of the 5CB induced the phase-separated monolayers, leading to the formation of ring patterns. The edge effect on the 5CB alignment decreases with the decrease of the height difference between the protruding islands and the surrounding monolayer and increases with the decrease of the size of the protruding islands. © 2011 Elsevier B.V

The SMX DNA Repair Tri-nuclease

The efficient removal of replication and recombination intermediates is essential for the maintenance of genome stability. Resolution of these potentially toxic structures requires the MUS81-EME1 endonuclease, which is activated at prometaphase by formation of the SMX tri-nuclease containing three DNA repair structure-selective endonucleases: SLX1-SLX4, MUS81-EME1, and XPF-ERCC1. Here we show that SMX tri-nuclease is more active than the three individual nucleases, efficiently cleaving replication forks and recombination intermediates. Within SMX, SLX4 co-ordinates the SLX1 and MUS81-EME1 nucleases for Holliday junction resolution, in a reaction stimulated by XPF-ERCC1. SMX formation activates MUS81-EME1 for replication fork and flap structure cleavage by relaxing substrate specificity. Activation involves MUS81’s conserved N-terminal HhH domain, which mediates incision site selection and SLX4 binding. Cell cycle-dependent formation and activation of this tri-nuclease complex provides a unique mechanism by which cells ensure chromosome segregation and preserve genome integrity