Abstract Sphingosine 1-phosphate (S1P) is a sphingolipid metabolite, which has emerged as an important signaling mediator participating in the regulation of multiple cellular processes. The discovery ...of a family of S1P receptors, together with the more recently identified intracellular targets, has provided fundamental understanding of the multi-faceted actions of S1P. Evidence from both in vitro and in vivo studies has implicated the S1P signaling system in the control of immunity, inflammation and many associated diseases. Enigmatically, S1P appears to have both pro- and anti-inflammatory effects depending on the cell context. Here, we review this emerging area and argue for a pivotal role for S1P, as a key mediator of the cytokine network, acting through juxtacrine signaling in the immune system.
FTY720, a sphingosine analog, is a novel immunosuppressant currently undergoing multiple clinical trials for the prevention of organ transplant rejection and treatment of various autoimmune diseases. ...Recent studies indicate an additional cytotoxic effect of FTY720 and its preclinical efficacy in a variety of cancer models, yet the underlying mechanisms remain unclear. We demonstrate here for the first time that FTY720 exhibits a potent, dose- and time-dependent cytotoxic effect in human ovarian cancer cells, even in the cells that are resistant to cisplatin, a commonly prescribed chemotherapeutic drug for treatment of ovarian cancer. In contrast to the previously reported cytotoxicity of FTY720 in many other cancer cell types, FTY720 kills ovarian cancer cells independent of caspase 3 activity and induces cellular swelling and cytoplasmic vacuolization with evident features of necrotic cell death. Furthermore, the presence of autophagic hallmarks, including an increased number of autophagosomes and the formation and accumulation of LC3-II, are observed in FTY720-treated cells before cell death. FTY720 treatment enhances autophagic flux as reflected in the increased LC3 turnover and p62 degradation. Notably, blockade of autophagy by either specific chemical inhibitors or siRNAs targeting Beclin 1 or LC3 resulted in aggravated necrotic cell death in response to FTY720, suggesting that FTY720-induced autophagy plays a self-protective role against its own cytotoxic effect. Thus, our findings not only demonstrate a new death pathway underlying the cytotoxic effect of FTY720, but also suggest that targeting autophagy could augment the anticancer potency, providing the framework for further development of FTY720 as a new chemotherapeutic agent for ovarian cancer treatment.
Around 10% of acute leukemias harbor a rearrangement of the MLL/KMT2A gene, and the presence of this translocation results in a highly aggressive, therapy‐resistant leukemia subtype with survival ...rates below 50%. There is a high unmet need to identify safer and more potent therapies for MLL‐rearranged (MLL‐r) leukemia that can be combined with established chemotherapeutics to decrease treatment‐related toxicities. The curaxin, CBL0137, has demonstrated nongenotoxic anticancer and chemopotentiating effects in a number of preclinical cancer models and is currently in adult Phase I clinical trials for solid tumors and hematological malignancies. The aim of our study was to investigate whether CBL0137 has potential as a therapeutic and chemopotentiating compound in MLL‐r leukemia through a comprehensive analysis of its efficacy in preclinical models of the disease. CBL0137 decreased the viability of a panel of MLL‐r leukemia cell lines (n = 12) and xenograft cells derived from patients with MLL‐r acute lymphoblastic leukemia (ALL, n = 3) in vitro with submicromolar IC50s. The small molecule drug was well‐tolerated in vivo and significantly reduced leukemia burden in a subcutaneous MV4;11 MLL‐r acute myeloid leukemia model and in patient‐derived xenograft models of MLL‐r ALL (n = 5). The in vivo efficacy of standard of care drugs used in remission induction for pediatric ALL was also potentiated by CBL0137. CBL0137 exerted its anticancer effect by trapping Facilitator of Chromatin Transcription (FACT) into chromatin, activating the p53 pathway and inducing an Interferon response. Our findings support further preclinical evaluation of CBL0137 as a new approach for the treatment of MLL‐r leukemia.
What's new?
Rearrangement of the MLL/KMT2A gene results in a highly aggressive, therapy‐resistant leukemia subtype, with high incidence in infants and survival rates below 50%. In this preclinical study, the authors found that a new, small‐molecule curaxin drug called CBL0137 significantly reduced leukemia burden in xenograft models, and also enhanced the response to standard chemotherapy drugs. CBL0137 mediated this effect through activation of the p53 and IFN pathways. These findings support further preclinical evaluation of CBL0137 as a new approach for the treatment of MLL‐r leukemia.
The BCR::ABL1 gene fusion initiates chronic myeloid leukemia (CML), however evidence has accumulated from studies of highly selected cohorts that variants in other cancer-related genes are associated ...with treatment failure. Nevertheless, the true incidence and impact of additional genetic abnormalities (AGAs) at diagnosis of chronic phase (CP)-CML is unknown. We sought to determine whether AGAs at diagnosis in a consecutive imatinib-treated cohort of 210 patients enrolled in the TIDEL-II trial influenced outcome despite a highly proactive treatment intervention strategy. Survival outcomes including overall survival, progression-free survival, failure-free survival and BCR::ABL1 kinase domain mutation acquisition were evaluated. Molecular outcomes were measured at a central laboratory and included major molecular response (MMR, BCR::ABL1 ≤0.1%IS), MR4 (BCR::ABL1 ≤0.01%IS) and MR4.5 (BCR::ABL1 ≤0.0032%IS). AGAs included variants in known cancer genes and novel rearrangements involving the formation of the Philadelphia chromosome. Clinical outcomes and molecular response were assessed based on the genetic profile and other baseline factors. AGAs were identified in 31% of patients. Potentially pathogenic variants in cancer-related genes were detected in 16% of patients at diagnosis (including gene fusions and deletions) and structural rearrangements involving the Philadelphia chromosome (Ph-associated rearrangements), detected in 18%. Multivariable analysis demonstrated that the combined genetic abnormalities plus the ELTS clinical risk score were independent predictors of lower molecular response rates and higher treatment failure. Despite a highly proactive treatment intervention strategy, first-line imatinib-treated patients with AGAs had poorer response rates. This data provides evidence for the incorporation of genomically-based risk assessment for CML.
Epithelioid inflammatory myofibroblastic sarcoma (eIMS) is characterised by perinuclear ALK localisation, CD30 expression and early relapse despite crizotinib treatment. We aimed to identify ...therapies to prevent and/or treat ALK inhibitor resistance.
Malignant ascites, from an eIMS patient at diagnosis and following multiple relapses, were used to generate matched diagnosis and relapse xenografts.
Xenografts were validated by confirmation of RANBP2-ALK rearrangement, perinuclear ALK localisation and CD30 expression. Although brentuximab-vedotin (BV) demonstrated single-agent activity, tumours regrew during BV therapy. BV resistance was associated with reduced CD30 expression and induction of ABCB1. BV resistance was reversed in vitro by tariquidar, but combination BV and tariquidar treatment only briefly slowed xenograft growth compared with BV alone. Combining BV with either crizotinib or ceritinib resulted in marked tumour shrinkage in both xenograft models, and resulted in prolonged tumour-free survival in the diagnosis compared with the relapse xenograft.
CD30 is a therapeutic target in eIMS. BV efficacy is limited by the rapid emergence of resistance. Prolonged survival with combination ALK and CD30-targeted-therapy in the diagnosis model provides the rationale to trial this combination in eIMS patients at diagnosis. This combination could also be considered for other CD30-positive, ALK-rearranged malignancies.
The transactivation of enhanced growth factor receptor (EGFR) by G protein-coupled receptor (GPCR) ligands is recognized as an important signaling mechanism in the regulation of complex biological ...processes, such as cancer development. Estrogen (E2), which is a steroid hormone that is intimately implicated in breast cancer, has also been suggested to function via EGFR transactivation. In this study, we demonstrate that E2-induced EGFR transactivation in human breast cancer cells is driven via a novel signaling system controlled by the lipid kinase sphingosine kinase-1 (SphK1). We show that E2 stimulates SphK1 activation and the release of sphingosine 1-phosphate (S1P), by which E2 is capable of activating the S1P receptor Edg-3, resulting in the EGFR transactivation in a matrix metalloprotease-dependent manner. Thus, these findings reveal a key role for SphK1 in the coupling of the signals between three membrane-spanning events induced by E2, S1P, and EGF. They also suggest a new signal transduction model across three individual ligand-receptor systems, i.e., "criss-cross" transactivation.
Biomarkers which better match anticancer drugs with cancer driver genes hold the promise of improved clinical responses and cure rates. We developed a precision medicine platform of rapid ...high‐throughput drug screening (HTS) and patient‐derived xenografting (PDX) of primary tumor tissue, and evaluated its potential for treatment identification among 56 consecutively enrolled high‐risk pediatric cancer patients, compared with conventional molecular genomics and transcriptomics. Drug hits were seen in the majority of HTS and PDX screens, which identified therapeutic options for 10 patients for whom no targetable molecular lesions could be found. Screens also provided orthogonal proof of drug efficacy suggested by molecular analyses and negative results for some molecular findings. We identified treatment options across the whole testing platform for 70% of patients. Only molecular therapeutic recommendations were provided to treating oncologists and led to a change in therapy in 53% of patients, of whom 29% had clinical benefit. These data indicate that in vitro and in vivo drug screening of tumor cells could increase therapeutic options and improve clinical outcomes for high‐risk pediatric cancer patients.
Synopsis
A precision diagnostic platform integrating genomics and transcriptomics with drug testing of patient's primary tumor cells in high throughput drug screening (HTS) and patient‐derived xenograft (PDX) was established to improve identification of therapies in high‐risk pediatric cancer patients.
Treatment options could be identified for 70% of patients across the four‐part platform.
HTS provided orthogonal proof of drug efficacy suggested by molecular analyses and identified many new drug responses without prior molecular hallmarks.
Effective treatments were observed in more than half of PDX models.
There was a strong correlation between HTS and PDX results, and the clinical responses in patients.
A precision diagnostic platform integrating genomics and transcriptomics with drug testing of patient's primary tumor cells in high throughput drug screening (HTS) and patient‐derived xenograft (PDX) was established to improve identification of therapies in high‐risk pediatric cancer patients.
Pediatric high grade gliomas (HGG) are primary brain malignancies that result in significant morbidity and mortality. One of the challenges in their treatment is inter- and intra-tumoral ...heterogeneity. Precision medicine approaches have the potential to enhance diagnostic, prognostic and/or therapeutic information. In this case study we describe the molecular characterization of a pediatric HGG and the use of an integrated approach based on genomic, in vitro and in vivo testing to identify actionable targets and treatment options. Molecular analysis based on WGS performed on initial and recurrent tumor biopsies revealed mutations in TP53, TSC1 and CIC genes, focal amplification of MYCN, and copy number gains in SMO and c-MET. Transcriptomic analysis identified increased expression of MYCN, and genes involved in sonic hedgehog signaling proteins (SHH, SMO, GLI1, GLI2) and receptor tyrosine kinase pathways (PLK, AURKA, c-MET). HTS revealed no cytotoxic efficacy of SHH pathway inhibitors while sensitivity was observed to the mTOR inhibitor temsirolimus, the ALK inhibitor ceritinib, and the PLK1 inhibitor BI2536. Based on the integrated approach, temsirolimus, ceritinib, BI2536 and standard therapy temozolomide were selected for further in vivo evaluation. Using the PDX animal model (median survival 28 days) we showed significant in vivo activity for mTOR inhibition by temsirolimus and BI2536 (median survival 109 and 115.5 days respectively) while ceritinib and temozolomide had only a moderate effect (43 and 75.5 days median survival respectively). This case study demonstrates that an integrated approach based on genomic, in vitro and in vivo drug efficacy testing in a PDX model may be useful to guide the management of high risk pediatric brain tumor in a clinically meaningful timeframe.
C-reactive protein (CRP), a well-recognized marker of atherosclerosis, has recently been suggested to have a direct proinflammatory effect. The constitutive expression of low levels of CRP in normal ...plasma suggests the likelihood that a natural factor exists to neutralize the effect of CRP. This factor(s) has not yet been identified. Method and Results- The proinflammatory effect of CRP was measured by the induction of inflammatory adhesion molecules in human umbilical vein endothelial cells (HUVECs). We show that CRP significantly induced upregulation of adhesion molecules in both protein and mRNA levels. The CRP-induced expression of these inflammatory adhesion molecules was completely suppressed when the cells were preincubated with a physiological concentration (1 mg/mL apolipoprotein A-I) of HDLs derived from human plasma (native HDL) or reconstituted HDL (rHDL) at a very low concentration (0.01 mg/mL apolipoprotein A-I). A novel mechanism of HDL inhibition is likely to operate, because (1) rHDL was 100 times more potent than native HDL, (2) preincubation with HDL and its sustained presence were obligatory, and (3) oxidized 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine was the fundamental active component.
The CRP-induced upregulation of inflammatory adhesion molecules in HUVECs was completely prevented by HDL via their oxidized phospholipid components.
Vascular endothelial cells are key targets for hyperglycemic damage that facilitates vascular inflammation and the vasculopathy associated with diabetes mellitus. However, the mechanisms underlying ...this damage remain undefined. We now demonstrate that hyperglycemia induces activation of sphingosine kinase (SphK), which represents a novel signaling pathway that mediates endothelial damage under ambient high glucose conditions. SphK activity was significantly increased in aorta and heart of streptozotocin-induced diabetic rats. Interestingly, this increase in SphK activity was prevented by insulin treatment, which achieved euglycemia in the diabetic animals. Hyperglycemia-induced increase in SphK activity was also evident in endothelial cells that received long-term exposure to high glucose (22 mmol/L). Studies using a small interfering RNA strategy demonstrated that endogenous SphK1, but not SphK2, is the major isoenzyme that was activated by high glucose. In addition, an increase in SphK1 phosphorylation was detected in a protein kinase C– and extracellular signal–regulated kinase 1/2–dependent manner, which accounts for the high glucose–induced increases in SphK activity. Importantly, inhibition of SphK1 by either a chemical inhibitor (N′,N′-dimethylsphingosine) or expression of a dominant-negative mutant of SphK1 (SphK), or SphK1-specific small interfering RNA, strongly protected endothelial cells against high glucose–induced damage, as characterized by an attenuation in the expression of proinflammatory adhesion molecules, adhesion of leukocytes to endothelial cells, and nuclear factor κB activation. Thus, interventions that target the SphK-signaling pathway may have the potential to prevent vascular lesions under hyperglycemic conditions.
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