Dual laser holography for in situ measurement of plasma facing component erosion (invited)

A digital holography (DH) surface erosion/deposition diagnostic is being developed for 3D imaging of plasma facing component surfaces in situ and in real time. Digital holography is a technique that utilizes lasers reflected from a material surface to form an interferogram, which carries information about the topology of the surface when reconstructed. As described in this paper, dual CO₂ lasers at 9.271 and 9.250 μm wavelengths illuminate the interrogated surface (at a distance of ∼1 m) in a region of ∼1 cm × 1 cm. The surface feature resolution is ∼0.1 mm in the plane of the surface, and the depth resolution ranges from ∼0.0001 to ∼2 mm perpendicular to the surface. The depth resolution lower limit is set by single-laser and detector optical limitations, while the upper limit is determined by 2π phase ambiguity of the dual-laser synthetic wavelength. Measurements have been made "on the bench" to characterize the single-laser and dual-laser DH configurations utilizing standard resolution targets and material targets that were previously exposed to high flux plasmas in either the Prototype Material Plasma Exposure eXperiment (Proto-MPEX) or the electro-thermal (ET) arc source. Typical DH measurements were made with 0.03 ms integration with an IR camera that can be framed at rates approaching 1.5 kHz. The DH diagnostic system is progressing toward in situ measurements of plasma erosion/deposition either on Proto-MPEX or the ET arc source.

Triceps on, alignment off? A comparison of total elbow arthroplasty component positioning with a triceps-on and a triceps-off approach

Introduction This retrospective review investigates whether the triceps-on approach obtains alignment of total elbow arthroplasty implants equivalent to a triceps-off approach. Methods The last 30 consecutive total elbow arthroplasties performed by the senior author were reviewed to identify the approach used and pathology treated. Initially, a triceps split and reflection approach was used, then a triceps-preserving approach. Two blinded reviewers measured the component alignment in standardised radiographs. Pearson's correlation coefficient was calculated to investigate inter/intra-observer and error. The two groups were compared using an unpaired Student t-test. Results There were 13 elbows in the triceps-off group and 17 in the triceps-on group. Pearson's coefficient was 0.75 for interobserver error, 0.89 for intra-observer error. There was no statistical difference between the achieved alignment. All ulna components were flexed with a mean angle deviation of 4.5 degrees in the triceps-off group and 5.7 degrees in the triceps on. Two (15%) ulna components in the triceps-off group were placed in over 5 degrees of flexion, compared with seven (44%) in the triceps-on group. Conclusion These results demonstrate no statistical difference in the achieved alignment between the two groups. Surgeons should beware of the tendency to place the ulna component in a flexed position, especially in the triceps-on approach.

Comparative learning curves for early complications in anatomical and reverse shoulder arthroplasty

Introduction There has been a significant increase in the implantation of reverse shoulder replacements over anatomical shoulder replacements in the past five years. Few comparative data exist comparing early complication rates and learning curves. This study aimed to evaluate the early complication rates and learning curves of a single surgeon series of anatomical and reverse shoulder replacements over the first five years of independent practice. Materials and methods The first 100 anatomical and 100 reverse shoulder replacements performed between July 2011 and July 2016 were reviewed to identify early complications. Cumulative sum plots were used to analyse the learning-curve effect. Results Early complications were noted in 4 anatomical and 17 reverse shoulder replacements. One of the anatomical and ten of the reverse shoulder replacements required a return to theatre within three months. The early complication rates were observed to be significantly higher in the reverse shoulder replacement group compared with the anatomical shoulder replacement group (odds ratio 4.9; 95% confidence interval 1.6-15.2, P 1/4 0.057). An inflection point on the anatomical shoulder replacement cumulative sum plot suggestive of a trend to consistent performance was reached at 16 cases. No inflection point was observed on the reverse shoulder replacement cohort. Conclusions We observed a significantly higher early complication rate within the reverse shoulder replacement cohort, with a tenfold increase in early reoperations. In comparison to the trend seen after 16 cases for anatomical shoulder replacement, no trend was seen in the reverse shoulder replacement cohort. This either reflects the higher complication rate seen in reverse shoulder replacement or that the learning curve extends beyond 100 cases, highlighting the need for extended performance monitoring.

Balance between senescence and apoptosis is regulated by telomere damage-induced association between p16 and caspase-3

Telomerase activation protects cells from telomere damage by delaying senescence and inducing cell immortalization, whereas telomerase inhibition mediates rapid senescence or apoptosis. However, the cellular mechanisms that determine telomere damage-dependent senescence versus apoptosis induction are largely unknown. Here, we demonstrate that telomerase instability mediated by silencing of sphingosine kinase 2 (SPHK2) and sphingosine 1-phosphate (S1P), which binds and stabilizes telomerase, induces telomere damage-dependent caspase-3 activation and apoptosis, but not senescence, in p16-deficient lung cancer cells or tumors. These outcomes were prevented by knockdown of a tumor-suppressor protein, transcription factor 21 (TCF21), or by ectopic expression of WT human telomerase reverse transcriptase (hTERT) but not mutant hTERT with altered S1P binding. Interestingly, SphK2-deficient mice exhibited accelerated aging and telomerase instability that increased telomere damage and senescence via p16 activation especially in testes tissues, but not in apoptosis. Moreover, p16 silencing in SphK2^-/- mouse embryonic fibroblasts activated caspase-3 and apoptosis without inducing senescence. Furthermore, ectopic WT p16 expression in p16-deficient A549 lung cancer cells prevented TCF21 and caspase-3 activation and resulted in senescence in response to SphK2/S1P inhibition and telomere damage. Mechanistically, a p16 mutant with impaired caspase-3 association did not prevent telomere damage-induced apoptosis, indicating that an association between p16 and caspase-3 proteins forces senescence induction by inhibiting caspase-3 activation and apoptosis. These results suggest that p16 plays a direct role in telomere damage-dependent senescence by limiting apoptosis via binding to caspase-3, revealing a direct link between telomere damage-dependent senescence and apoptosis with regards to aging and cancer.

Age and Alzheimer's pathology disrupt default mode network functioning via alterations in white matter microstructure but not hyperintensities

The default mode network (DMN) comprises defined brain regions contributing to internally-directed thought processes. Reductions in task-induced deactivation in the DMN have been associated with increasing age and poorer executive task performance, but factors underlying these functional changes remain unclear. We investigated contributions of white matter (WM) microstructure, WM hyperintensities (WMH) and Alzheimer's pathology to age-related alterations in DMN function. Thirty-five cognitively normal older adults and 29 younger adults underwent working memory task fMRI and diffusion tensor imaging. In the older adults, we measured cerebrospinal fluid tau and Aβ₄₂ (markers of AD pathology), and WMH on FLAIR imaging (marker of cerebrovascular disease). We identified a set of regions showing DMN deactivation and a set of inter-connecting WM tracts (DMN-WM) common to both age groups. There were negative associations between DMN deactivation and task performance in older adults, consistent with previous studies. Decreased DMN deactivation was associated with AD pathology and WM microstructure but not with WMH volume. Mediation analyses showed that WM microstructure mediated declines in DMN deactivation associated with both aging and AD pathology. Together these results suggest that AD pathology may exert a "second-hit" on WM microstructure, over-and-above the effects of age, both contributing to diminished DMN deactivation in older adults.

Spared behavioral repetition effects in Alzheimer's disease linked to an altered neural mechanism at posterior cortex

OBJECTIVE

Individuals with dementia of the Alzheimer type (AD) classically show disproportionate impairment in measures of working memory, but repetition learning effects are relatively preserved. As AD affects brain regions implicated in both working memory and repetition effects, the neural basis of this discrepancy is poorly understood. We hypothesized that the posterior repetition effect could account for this discrepancy due to the milder effects of AD at visual cortex.

METHOD

Participants with early AD, amnestic mild cognitive impairment (MCI), and healthy controls performed a working memory task with superimposed repetition effects while electroencephalography was collected to identify possible neural mechanisms of preserved repetition effects.

RESULTS

Participants with AD showed preserved behavioral repetition effects and a change in the posterior repetition effect.

CONCLUSION

Visual cortex may play a role in maintained repetition effects in persons with early AD.

In Vitro and In Vivo Antitumor and Anti-Inflammatory Capabilities of the Novel GSK3 and CDK9 Inhibitor ABC1183

Glycogen synthase kinase-3s (GSK3α and GSK3β) are constitutively active protein kinases that target over 100 substrates, incorporate into numerous protein complexes, and regulate such vital cellular functions as proliferation, apoptosis, and inflammation. Cyclin-dependent kinase 9 (CDK9) regulates RNA production as a component of positive transcription elongation factor b and promotes expression of oncogenic and inflammatory genes. Simultaneous inhibition of these signaling nodes is a promising approach for drug discovery, although previous compounds exhibit limited selectivity and clinical efficacy. The novel diaminothiazole ABC1183 is a selective GSK3α/β and CDK9 inhibitor and is growth-inhibitory against a broad panel of cancer cell lines. ABC1183 treatment decreases cell survival through G2/M arrest and modulates oncogenic signaling through changes in GSK3, glycogen synthase, and β-catenin phosphorylation and MCL1 expression. Oral administration, which demonstrates no organ or hematologic toxicity, suppresses tumor growth and inflammation-driven gastrointestinal disease symptoms, owing in part to downregulation of tumor necrosis factor α and interleukin-6 proinflammatory cytokines. Therefore, ABC1183 is strategically poised to effectively mitigate multiple clinically relevant diseases.

Global Cerebral Atrophy Detected by Routine Imaging: Relationship with Age, Hippocampal Atrophy, and White Matter Hyperintensities

BACKGROUND AND PURPOSE

Interpreting the clinical significance of moderate-to-severe global cerebral atrophy (GCA) is a conundrum for many clinicians, who visually interpret brain imaging studies in routine clinical practice. GCA may be attributed to normal aging, Alzheimer's disease (AD), or cerebrovascular disease (CVD). Understanding the relationships of GCA with aging, AD, and CVD is important for accurate diagnosis and treatment decisions for cognitive complaints.

METHODS

To elucidate the relative associations of age, moderate-to-severe white matter hyperintensities (WMHs), and moderate-to-severe medial temporal lobe atrophy (MTA), with moderate-to-severe GCA, we visually rated clinical brain imaging studies of 325 participants from a community based sample. Logistic regression analysis was conducted to assess the relations of GCA with age, WMH, and MTA.

RESULTS

The mean age was 76.2 (±9.6) years, 40.6% were male, and the mean educational attainment was 15.1 (±3.7) years. Logistic regression results demonstrated that while a 1-year increase in age was associated with GCA (OR = 1.04; P = .04), MTA (OR = 3.7; P < .001), and WMH (OR = 8.80; P < .001) were strongly associated with GCA in our study population. Partial correlation analysis showed that the variance of GCA explained by age is less than the variance attributed to MTA and WMH (r = .13, .21, and .43, respectively).

CONCLUSIONS

Moderate-to-severe GCA is most likely to occur in the presence of AD or CVD and should not be solely attributed to age when evaluating clinical imaging findings in the workup of cognitive complaints. Developing optimal diagnostic and treatment strategies for cognitive decline in the setting of GCA requires an understanding of its risk factors in the aging population.

The sphingosine kinase 2 inhibitor ABC294640 displays anti-non-small cell lung cancer activities in vitro and in vivo

Non-small cell lung cancer (NSCLC) accounts for about 85-90% of lung cancer cases, and is the number one killer among cancers in the United States. The majorities of lung cancer patients do not respond well to conventional chemo- and/or radio-therapeutic regimens, and have a dismal 5-year survival rate of ∼15%. The recent introduction of targeted therapy and immunotherapy gives new hopes to NSCLC patients, but even with these agents, not all patients respond, and responses are rarely complete. Thus, there is still an urgent need to identify new therapeutic targets in NSCLC and develop novel anti-cancer agents. Sphingosine kinase 2 (SphK2) is one of the key enzymes in sphingolipid metabolism. SphK2 expression predicts poor survival in NSCLC patients, and is associated with Gefitinib-resistance. In this study, the anti-NSCLC activities of ABC294640, the only first-in-class orally available inhibitor of SphK2, were explored. The results obtained indicate that ABC294640 treatment causes significant NSCLC cell apoptosis, cell cycle arrest and suppression of tumor growth in vitro and in vivo. Moreover, lipidomics analyses revealed the complete signature of ceramide and dihydro(dh)-ceramide species in the NSCLC cell-lines with or without ABC294640 treatment. These findings indicate that sphingolipid metabolism targeted therapy may be developed as a promising strategy against NSCLC.

Abstract B190: Antitumor effects of ABC131, a novel diaminothiazole inhibitor of tubulin

Background: Several established chemotherapy drugs, including vinca alkaloids and paclitaxel, block tumor cell division by disrupting microtubule dynamics, ultimately leading to apoptosis. For decades, these drugs have remained central components for cancer therapy despite their limitations, which include hematologic and neurologic toxicities and the propensity for tumor cells to develop resistance to these agents. In characterizing a new series of diaminothiazoles, we focused on defining the mechanism of action and the antitumor activity of a novel compound (ABC131). Materials and Methods: A library of DATs was synthesized by reaction of substituted phenylisothiocyanates, tetramethylguanidine and substituted phenylacylbromides, and tested for cytotoxicity against several tumor cell lines. These compounds were further assessed for their mechanism(s) of action using a variety of cellular and biochemical assays, and selected compounds were tested in vivo for toxicity and antitumor activity in syngeneic allograft models using PAN02 (pancreatic), B16 (melanoma) or TRAMP (prostate) tumor cells. Results: A library of more than 90 diaminothiazoles was produced, and these compounds demonstrated IC50s for cytotoxicity against PAN02 cells ranging from 0.04 to &gt;100 μM. Several of these compounds depolymerized microtubules in cells. One such compound, ABC131, was selected for detailed characterization because of the potent antiproliferative activity against a panel of murine and human tumor cells (IC50s ~30-300 nM). ABC131 caused dose-dependent microtubule depolymerization in cells, in parallel with G2/M cell cycle arrest and apoptosis. Kinome profiling demonstrated that ABC131 did not significantly inhibit any of more than 400 protein kinases, including cyclin-dependent kinases, which are inhibited by several compounds within this library. Importantly, transport studies demonstrated that ABC131 is not a substrate for P-glycoprotein, a well-established mechanism for resistance to many other anti-microtubule drugs. Oral administration of ABC131 at doses as low as 2 mg/kg/day inhibited tumor growth in all models tested (PAN02, B16, and TRAMP). Pharmacokinetic and biodistribution analyses of ABC131 demonstrated &gt;10-fold IC50 levels in the plasma and tumors following oral dosing of mice. Although ABC131 was rapidly cleared from the plasma, liver, and brain, &gt;IC50 levels of ABC131 persisted in tumors for at least 7 hours after oral dosing. No hematologic or major organ toxicity was observed in mice treated with ABC131 at 500 mg/kg/day for 7 days. A model of peripheral neuropathy in rats demonstrated markedly reduced toxicity for ABC131 compared with paclitaxel. Conclusions: ABC131 is a new potential anticancer agent with several advantages over established anti-microtubule drugs, including oral bioavailability, lack of sensitivity to P-glycoprotein, lack of hematologic toxicity, and reduced neuropathy. These properties of ABC131 are highly supportive of its development as an anticancer drug.

Citation Format: Charles D. Smith, Randy S. Schrecengost, Yan Zhuang, Lynn W. Maines, Staci N. Keller, Ryan A. Smith, Cecelia L. Green. Antitumor effects of ABC131, a novel diaminothiazole inhibitor of tubulin [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B190.

Deconstructing normal pressure hydrocephalus: Ventriculomegaly as early sign of neurodegeneration

Idiopathic normal pressure hydrocephalus (NPH) remains both oversuspected on clinical grounds and underconfirmed when based on immediate and sustained response to cerebrospinal fluid diversion. Poor long-term postshunt benefits and findings of neurodegenerative pathology in most patients with adequate follow-up suggest that hydrocephalic disorders appearing in late adulthood may often result from initially unapparent parenchymal abnormalities. We critically review the NPH literature, highlighting the near universal lack of blinding and controls, absence of specific clinical, imaging, or pathological features, and ongoing dependence for diagnostic confirmation on variable cutoffs of gait response to bedside fluid-drainage testing. We also summarize our long-term institutional experience, in which postshunt benefits in patients with initial diagnosis of idiopathic NPH persist in only 32% of patients at 36 months, with known revised diagnosis in over 25% (Alzheimer's disease, dementia with Lewy bodies, and progressive supranuclear palsy). We postulate that previously reported NPH cases with "dual" pathology (ie, developing a "second" disorder) more likely represent ventriculomegalic presentations of selected neurodegenerative disorders in which benefits from shunting may be short-lived, with a consequently unfavorable risk-benefit ratio. Ann Neurol 2017;82:503-513.

ABC294640, A Novel Sphingosine Kinase 2 Inhibitor, Induces Oncogenic Virus-Infected Cell Autophagic Death and Represses Tumor Growth

Kaposi sarcoma-associated herpes virus (KSHV) is the etiologic agent of several malignancies, including Kaposi sarcoma and primary effusion lymphoma (PEL), which preferentially arise in HIV⁺ patients and lack effective treatment. Sphingosine kinase 2 (SphK2) is a key factor within sphingolipid metabolism, responsible for the conversion of proapoptotic ceramides to antiapoptotic sphingosine-1-phosphate (S1P). We have previously demonstrated that targeting SphK2 using a novel selective inhibitor, ABC294640, leads to the accumulation of intracellular ceramides and induces apoptosis in KSHV-infected primary endothelial cells and PEL tumor cells but not in uninfected cells. In this study, we found that ABC294640 induces autophagic death instead of apoptosis in a KSHV long-term-infected immortalized endothelial cell-line, TIVE-LTC, but not in uninfected TIVE cells, through the upregulation of LC3B protein. Transcriptomic analysis indicates that many genes related to cellular stress responses, cell cycle/proliferation, and cellular metabolic process are altered in TIVE-LTC exposed to ABC294640. One of the candidates, Egr-1, was found to directly regulate LC3B expression and was required for the ABC294640-induced autophagic death. By using a Kaposi sarcoma-like nude mice model with TIVE-LTC, we found that ABC294640 treatment significantly suppressed KSHV-induced tumor growth in vivo, which indicates that targeting sphingolipid metabolism, especially SphK2, may represent a promising therapeutic strategy against KSHV-related malignancies. Mol Cancer Ther; 16(12); 2724-34. ©2017 AACR.

The colonisation of the glenohumeral joint by Propionibacterium acnes is not associated with frozen shoulder but is more likely to occur after an injection into the joint

AIMS

Our aim was to investigate the prevalence of Propionibacterium (P.) acnes in the subcutaneous fat and capsule of patients undergoing shoulder surgery for frozen shoulder or instability.

PATIENTS AND METHODS

A total of 46 patients undergoing either an arthroscopic capsular release or stabilisation had biopsies taken from the subcutaneous fat and capsule of the shoulder at the time of surgery. These samples were sent for culture in enrichment, and also for Nucleic Acid Amplification testing. The prevalence of P. acnes and other microbes was recorded. Fisher's exact test of binary variables was used to calculate the association with significance set at p < 0.05. Assessment of influence of independent variables including a pre-operative glenohumeral injection, fat colonisation and gender, was undertaken using binary linear regression.

RESULTS

A total of 25 patients (53%) had P. acnes in one or more tissue samples and 35 (74%) had other bacterial species. The same microbe was found in the subcutaneous fat and the capsule in 13 patients (28%). There was no statistically significant association between the surgical pathology and capsular colonisation with P. acnes (p = 0.18) or mixed identified bacterial species (p = 0.77). Male gender was significantly associated with an increased capsular colonisation of P. acnes (odds ratio (OR) 12.38, 95% confidence interval (CI) 1.43 to 106.77, p = 0.02). A pre-operative glenohumeral injection was significantly associated with capsular P. acnes colonisation (OR 5.63, 95% CI 1.07 to 29.61, p = 0.04. Positive fat colonisation with P. acnes was significantly associated with capsular P. acnes (OR 363, 95% CI 20.90 to 6304.19, p < 0.01). Regression models pseudo R² found fat colonisation with P. acnes to explain 70% of the variance of the model. Patients who had a pre-operative glenohumeral injection who were found intra-operatively to have fat colonisation with P. acnes had a statistically significant association with colonisation of their capsule with P. acnes (OR 165, 95% CI 13.51 to 2015.24, p < 0.01).

CONCLUSION

These results show a statistically significant association between subcutaneous skin P. acnes culture and P. acnes capsular culture, especially when the patient has undergone a previous injection. The results refute the hypothesis that P. acnes causes frozen shoulder. Cite this article: Bone Joint J 2017;99-B:1067-72.

Abstract 5474: Sphingosine kinase 2/sphingosine 1-phosphate signaling regulates p16 mediated accelerated aging in normal somatic tissues and tcf21 mediated tumor suppression in lung cancer

Sphingosine 1-phosphate (S1P), a pro-proliferative sphingolipid generated by Sphingosine Kinases is upregulated in many cancers. Telomerase (hTERT), is a ribonucleoprotein that extends the ends of chromosomes (telomeres), to promote lung cancer growth. We discovered that SK2 generated S1P binds and stabilizes telomerase in the nuclear periphery by allosterically mimicking protein phosphorylation. Mechanistically, S1P binding protected telomerase from MKRN1 mediated degradation thereby preventing telomere dysfunction and senescence. The objective of this study is to delineate the molecular mechanism of SK2-S1P mediated telomere dysfunction in aging and lung cancer. SK2 knockout mice tissues showed increased telomeric DNA damage and senescence associated-beta galactosidase activity. Moreover, SK2 knockout mice displayed aging phenotypes by reduced subcutaneous fat, atrophy in spleens and hypoplasia in mice testes. Also, SK2 knockout fibroblasts showed increased senescence and robust p16 expression and interestingly, p16 ablation rescued SK2 knockout fibroblasts from senescence. Importantly, we found SK2 and telomerase protein levels to be upregulated in lung cancer tumor tissues (n=48). Mechanistically, pharmacological inhibition of SK2 by ABC294640 (in Phase II clinical trials) leads to telomere dysfunction in A549 cells and interestingly wild type and a phosphomimicking S921D-hTERT mutant of human telomerase overexpression prevented telomere dysfunction whereas S1P defective mutant D684A-hTERT did not. In vivo, inhibition of SK2 by ABC294640 or shRNA knockdown displayed reduced tumor volume, decreased telomerase protein levels and increased TUNEL positive cells. Interestingly, qPCR based gene array revealed robust increase in TCF21 tumor suppressor in stable shSK2 tumors. Furthermore, shRNA against TCF21 following SCID mice xenograft studies showed protection against ABC294640 induced tumor suppression. Interestingly, SK2 inhibition showed ATM/ATR kinase mediated p-CHK1 increase and subsequent activation of caspase-3 in both in vivo and in vitro experiments and stable TCF21 knockdown prevents apoptotic cell death. Importantly, p16 overexpression in p16 deficient A549 lung cancer cells prevented caspase-3 activation and leading to senescence induction following inhibition of SK2-S1P by ABC294640 or shRNA against SK2. Overall, our data suggest that SK2-S1P regulates telomere dysfunction through p16 mediated aging in normal somatic tissues and TCF21 mediated tumor suppression in lung cancer and interestingly SK2-S1P and p16 acts as a molecular switch between senescence and apoptosis in normal and cancer cells respectively.

Citation Format: Shanmugam Panneer Selvam, Marion Cooley, Kristi Helke, Elizabeth Garrett-Mayer, Charles D. Smith, Besim Ogretmen. Sphingosine kinase 2/sphingosine 1-phosphate signaling regulates p16 mediated accelerated aging in normal somatic tissues and tcf21 mediated tumor suppression in lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5474. doi:10.1158/1538-7445.AM2017-5474

Clinically silent Alzheimer's and vascular pathologies influence brain networks supporting executive function in healthy older adults

Aging is associated with declines in executive function. We examined how executive functional brain systems are influenced by clinically silent Alzheimer's disease (AD) pathology and cerebral white-matter hyperintensities (WMHs). Twenty-nine younger adults and 34 cognitively normal older adults completed a working memory paradigm while functional magnetic resonance imaging was performed. Older adults further underwent lumbar cerebrospinal fluid draw for the assessment of AD pathology and FLAIR imaging for the assessment of WMHs. Accurate working memory performance in both age groups was associated with high fronto-visual functional connectivity (fC). However, in older adults, higher expression of fronto-visual fC was linked with lower levels of clinically silent AD pathology. In addition, AD pathology and WMHs were each independently related to increased functional magnetic resonance imaging response in the left dorsolateral prefrontal cortex, a pattern associated with slower task performance. Our results suggest that clinically silent AD pathology is related to lower expression of a fronto-visual fC pattern supporting executive task performance. Further, our findings suggest that AD pathology and WMHs appear to be linked with ineffective increases in frontal response in CN older adults.

A Phase I Study of ABC294640, a First-in-Class Sphingosine Kinase-2 Inhibitor, in Patients with Advanced Solid Tumors

Purpose: Sphingosine kinases (SK1 and SK2) regulate tumor growth by generating the mitogenic and proinflammatory lipid sphingosine 1-phosphate (S1P). This phase I study investigated the safety, pharmacokinetics, pharmacodynamics, and antitumor activity of ABC294640, a first-in-class orally available inhibitor of SK2.Experimental Design: Escalating doses of ABC294640 were administered orally to patients with advanced solid tumors in sequential cohorts at the following dose levels: 250 mg qd, 250 mg bid, 500 mg bid, and 750 mg bid, continuously in cycles of 28 days. Serial blood samples were obtained to measure ABC294640 concentrations and sphingolipid profiles.Results: Twenty-two patients were enrolled, and 21 received ABC294640. The most common drug-related toxicities were nausea, vomiting, and fatigue. Among the 4 patients at 750 mg bid, one had dose-limiting grade 3 nausea and vomiting, and 2 were unable to complete cycle 1 due to diverse drug-related toxicities. The 500 mg bid dose level was established as the recommended phase II dose. ABC294640 administration resulted in decreases in S1P levels over the first 12 hours, with return to baseline at 24 hours. The best response was a partial response in a patient with cholangiocarcinoma at 250 mg qd, and stable disease was observed in 6 patients with various solid tumors across dose levels.Conclusions: At 500 mg bid, ABC294640 is well tolerated and achieves biologically relevant plasma concentrations. Changes in plasma sphingolipid levels may provide a useful pharmacodynamic biomarker for ABC294640. Clin Cancer Res; 23(16); 4642-50. ©2017 AACR.

Applying a high-throughput fluorescence polarization assay for the discovery of chemical probes blocking La:RNA interactions in vitro and in cells

The RNA-binding protein La is overexpressed in a number of tumor tissues and is thought to support tumorigenesis by binding to and facilitating the expression of mRNAs encoding tumor-promoting and anti-apoptotic factors. Hence, small molecules able to block the binding of La to specific RNAs could have a therapeutic impact by reducing the expression of tumor-promoting and anti-apoptotic factors. Toward this novel therapeutic strategy, we aimed to develop a high-throughput fluorescence polarization assay to screen small compound libraries for molecules blocking the binding of La to an RNA element derived from cyclin D1 mRNA. Herein, we make use of a robust fluorescence polarization assay and the validation of primary hits by electrophoretic mobility shift assays. We showed recently that La protects cells against cisplatin treatment by stimulating the protein synthesis of the anti-apoptotic factor Bcl2. Here, we show by RNA immunoprecipitation experiments that one small compound specifically impairs the association of La with Bcl2 mRNA in cells and sensitizes cells for cipslatin-induced cell death. In summary, we report the application of a high-throughput fluorescence polarization assay to identify small compounds that impair the binding of La to target RNAs in vitro and in cells.