Abstract 3039: Decreased pH-sensitive potassium channel gene expressions in glioblastomas compared to oligodendrogliomas detected with house keeping genes may shift glioblastoma membrane potentials towards proton efflux to the microenvironment

Glial buffering of K+ prevents seizures, hence gliomas in patients on anticonvulsants may harbor potassium related anomalies. Cell membrane potentials are very sensitive to K+ and may link to tumor acidosis when they become more positive than the equilibrium potential for H+ ions (Vaupel, P, et al., Cancer Res, 1989). Kir5.1(KCNJ16) heterodimerizes with Kir4.1(KCNJ10), a major glial potassium channel, to stop K+ conductance in acidosis. Trek1&2(KCNK2&10) are also pH sensitive K+ channels. Glioblastomas (more malignant and invasive) versus oligodendrogliomas showed decreased KCNJ16 in patients on anticonvulsants (Beckner, ME, Proc AACR, A2319, 2021). However, loss of genomic integrity in tumors and potential variation between assays prompted house keeping gene (HKG) normalization to lessen confounding factors. REMBRANDT (12/31/2020, Georgetown Database of Cancer) had 220 glioblastomas and 67 oligodendrogliomas with microarray gene expression via medians of each reporter (1-8 per gene) in Adobe Flash readouts (ended 1/1/21). A subgroup, 75 glioblastomas and 24 oligodendroglioma patients, took anticonvulsants. Comparison of genes of interest (GOI) initially had t tests between types of gliomas in the subgroup. Here, differences between glioma types for each GOI reporter were compared to differences for HKGs (PPIA, RPLP0, YWHAZ, and B2M). In gliomas with anticonvulsants, paired 2-tailed t tests for a null difference of median reporters between tumor types were less sensitive than new comparisons of oligodendroglioma minus glioblastoma (OMG) differences for GOIs versus OMG differences in HKGs. For KCNJ16, the t test, p = 0.015, for a decrease in glioblastomas (versus oligodendrogliomas) in initial studies improved to p ≤ 0.0001 by using HKGs in comparisons. The KCNK2&10 decrease in glioblastomas became significant, p = 0.047. Among other glycolytic and acidosis related genes, CA12, GLO1&2, PFKFB1&3, showed stronger trends, with p values from 0.08 to 0.13 (decreases and increase) in comparisons using HKGs. Conclusion: HKG normalization presumably corrects for loss of genomic integrity, assay variations, etc. in comparisons using microarrays of different tumors. The pH-sensitive K+ channel genes studied here were expressed less in glioblastomas. The resulting pH-insensitive K+ distributions in glioblastomas putatively shift their cell membrane potentials to less negative values which are sufficient to allow passive H+ efflux that causes extracellular acidosis with accompanying activation of invasion. Acknowledgement: The data utilized in this study were provided by the Georgetown Database of Cancer (G-DOC), a project of the Georgetown Lombardi Comprehensive Cancer Center designed to provide translational research tools to the scientific community.

Citation Format: Marie E. Beckner. Decreased pH-sensitive potassium channel gene expressions in glioblastomas compared to oligodendrogliomas detected with house keeping genes may shift glioblastoma membrane potentials towards proton efflux to the microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3039.

Abstract 2319: Expressions of genes encoding pH-sensitive potassium channels differ between oligodendrogliomas and glioblastomas with potential metabolic effects

Potassium, the major intracellular cation, is released by neurons as they fire action potentials. Glial cells take up released K+ ions and later return them. Faulty glial K+ buffering contributes to seizures. Previously, in brain tumor patients treated with anticonvulsants, KCNJ16 (Kir5.1 K+ channel) had decreased expression (p=0.014793) in 75 glioblastomas vs. 24 oligodendrogliomas (18.78 & 50.77 mo. survival, respectively) (Beckner, Expressions of genes for connexins & Kir5.1 differ between oligodendrogliomas & glioblastomas in patients treated with anticonvulsants. Proceedings of 111 AACR Meeting, 2020, Abst#3726). Kir5.1 forms heteromeric channels with Kir4.1 (major glial K+ channel without energy requirement) to provide sensitivity to acidosis. Loss of Kir5.1 renders cells retaining Kir4.1 resistant to acidosis.

Hypothesis: Gene expressions for multiple pH-sensitive K+ channels are altered between tumor types. Also, because K+ may associate with toxic byproducts of glycolysis, expression of GLO1 & 2, genes for glyoxalases, differ between tumor types. The REMBRANDT database (11/17/2020, Georgetown Database of Cancer (G-DOC®)) contains 220 glioblastoma & 67 oligodendroglioma patients with microarray gene expressions determined by reporter probes (1-3/gene of interest). Of these, 75 glioblastoma & 24 oligodendroglioma patients were treated with anticonvulsants. 2-tailed t-tests, paired via reporters, were performed. Expression of KCNJ16 (2 reporters), was decreased in 220 glioblastomas vs. 67 oligodendrogliomas, p=0.05004. Therefore, tumor patients treated with anticonvulsants showed a greater decrease in KCNJ16 expression in glioblastomas. They also had decreased expression (p=0.05158) of combined KCNK2(TREK1, 1 reporter) & KCNK10(TREK2, 3 reporters) and trends for decreased expressions of KCNK10(TREK2) alone (p=0.10462) & KCNK9 (TASK3) (p=0.21802), & increased expression of KCNK3 (TASK1) (p=0.20019). Glioblastomas had a trend for decreased combined expression (p=0.20504) of glyoxalase genes (GLO1 & GLO2, 1 reporter each). House-keeping genes, 3-8 reporters/gene, did not differ.

Conclusion: Gene expressions show trends & significant differences among pH sensitive K+ channels in glioblastomas vs. oligodendrogliomas. Decreased expression of glyoxalases in glioblastomas, consistent with buildup of toxic glycolytic byproducts, highlights the importance of altered tumor cell K+ channeling. Loss of Kir5.1's modulation of Kir4.1 (primary non-ATP dependent glial K+ channel) resulting in putative anomalous K+ uptake may mitigate effects of toxic glycolytic byproducts in acidosis.

Acknowledgement: Data were provided by the Georgetown Database of Cancer (G-DOC®), a project of the Georgetown Lombardi Comprehensive Cancer Center to provide advanced translational research tools to the scientific community.

Citation Format: Marie E. Beckner. Expressions of genes encoding pH-sensitive potassium channels differ between oligodendrogliomas and glioblastomas with potential metabolic effects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2319.

Reliability of corticospinal excitability estimates for the vastus lateralis: Practical considerations for lower limb TMS task selection

Transcranial magnetic stimulation (TMS) is increasingly used to examine lower extremity corticospinal excitability (CSE) in clinical and sports research. Because CSE is task-specific, there is growing emphasis on the use of ecological tasks. Nevertheless, the comparative reliability of CSE measurements during established (e.g. knee extensions; KE) and more recent ecological (e.g. squats; SQT) lower extremity tasks has received less attention. The aim of this study was to compare the test-retest reliability of CSE, force, and muscle activity (EMG) during isometric SQT and KE. 19 right-footed men (age: 25 ± 5 yrs) with similar fitness and body composition performed SQT (N = 7) or KE (N = 12) on two consecutive days. Force and EMG were recorded during maximum voluntary isometric contractions (MVC). Corticospinal excitability was determined in the dominant leg during light (15% MVC) contractions based on motor evoked potential (MEP) stimulus-response-curves (SRC). Test-retest reliability, absolute agreement, and consistency were determined for force, EMG, and SRC MEP maximum (MEPMAX) and rising phase midpoint (V50). As a secondary analysis, all outcomes were compared between groups with mixed-methods ANCOVAs (Task × Time, covariate: body-fat-percentage). Compared with SQT, KE displayed better test-retest reliability and agreement for MEPMAX whereas V50, force, and EMG were similarly reliable. Force (p = 0.01) and MEPMAX (p = 0.02) were also greater during KE despite a similar V50 (p = 0.11). Differences in test-retest reliability, absolute agreement, and between-group comparisons highlight the need to carefully select lower limb TMS assessment tasks and encourage future efforts to balance ecological validity with statistical sensitivity.

Characterizing off-target corticospinal responses to double-cone transcranial magnetic stimulation

INTRODUCTION

The double-cone coil (D-CONE) is frequently used in transcranial magnetic stimulation (TMS) experiments that target the motor cortex (M1) lower-limb representation. Anecdotal evidence and modeling studies have shed light on the off-target effects of D-CONE TMS but the physiological extent remains undetermined.

PURPOSE

To characterize the off-target effects of D-CONE TMS based on bilateral corticospinal responses in the legs and hands.

METHODS

Thirty (N = 30) participants (9 women, age: 26 ± 5yrs) completed a stimulus-response curve procedure with D-CONE TMS applied to the dominant vastus lateralis (cVL) and motor-evoked potentials (MEPs) recorded in each active VL and resting first dorsal interosseous (FDI). As a positive control (CON), the dominant FDI was directly targeted with a figure-of-eight coil and MEPs were similarly recorded in each active FDI and resting VL. MEP_MAX, V50 and MEP latencies were compared with repeated-measures ANOVAs or mixed-effects analysis and Bonferroni-corrected pairwise comparisons.

RESULTS

Off-target responses were evident in all muscles, with similar MEP_MAX in the target (cVL) and off-target (iVL) leg (p = 0.99) and cFDI compared with CON (p = 0.99). cFDI and CON MEP_MAX were greater than iFDI (p < 0.01). A main effect of target (p < 0.001) indicated that latencies were shorter with CON but similar in all muscles with D-CONE.

DISCUSSION

Concurrent MEP recordings in bilateral upper- and lower-extremity muscles confirm that lower-limb D-CONE TMS produces substantial distance-dependent off-target effects. In addition to monitoring corticospinal responses in off-target muscles to improve targeting accuracy in real-time, future studies may incorporate off-target information into statistical models post-hoc.

Abstract 3726: Expressions of genes for connexins and Kir5.1 differ between oligodendrogliomas and glioblastomas in patients treated with anticonvulsants

Background: Glia in the CNS buffer potassium ions released by neurons as they fire action potentials. Glial activity occurs at synapses, along axons, and possibly throughout the glial network. Faulty glial potassium buffering can contribute to seizure activity via altered synaptic dynamics.

Hypothesis: Contrasting gene expression patterns in glial mediators of potassium buffering are proposed to exist among different types of gliomas.

Methods: The REMBRANDT database (12/4/2019, Georgetown Database of Cancer (G-DOC®)) contains 75 glioblastoma and 24 oligodendroglioma patients, treated with anticonvulsants to control seizures, whose tumor gene expressions were determined by reporter probes on microarrays. Differences were found with t-tests, paired via reporter probes when possible.

Results: Based on two reporters, KCNJ16 (encodes the Kir5.1 potassium channel) had decreased expression in glioblastomas versus oligodendrogliomas, p=0.014793, 2-tailed. Functionally, Kir5.1 can form heteromeric channels with Kir4.1 to conduct potassium with altered sensitivity to pH. Based on one reporter per gene, three astrocytic-type connexin genes, GJA1(Cx43), GJB2(Cx26) and GJB6(Cx30), as a group, were expressed more so in glioblastomas than in oligodendrogliomas, p=0.047647, 1-tailed. Finding only one oligodendrocytic-type connexin gene with only one reporter probe available in REMBRANDT prevented reverse comparisons. Using two reporters per gene, ATP1A2 (encodes the glial version of Na,K-ATPase alpha) was expressed more than the neuronal version of this transporter (ATP1A1) in glioblastomas and in oligodendrogliomas, p=0.027755 and 0.034492, respectively, 2-tailed, unpaired. Possibly expression of ATP1A1 found at low levels in the gliomas reflects residual neuronal elements. Significant differences between the two types of gliomas were undetectable for many other known and potential glial mediators of potassium buffering using 2 reporter probes each for KCNJ10(Kir4.1), SLC12A2(NKCC1), KCNK3(TASK1), KCNK9(TASK3), SLC12A6(KCC3), KCNA2(Kv1.2), KCNA6(Kv1.6), KCNQ3(Kv7.3), KCNJ13(Kir7.1) & KCNK1(TWIK1), and 4 reporter probes for KCNMA1(BK-alpha1). Several other potassium channels and transporters either have only one reporter available in REMBRANDT or have not been tested yet. No significant differences in the 2 types of gliomas were detected for six house-keeping genes, 3 to 8 reporters per gene.

Conclusion: Gene expression patterns for at least some glial potassium buffering mediators differ between glioblastomas and oligodendrogliomas at levels detectable with minimal numbers of reporter probes available for most of the genes encoding potential glial potassium buffering mediators. Potassium buffering mediators in gliomas warrant further investigation. Importantly, the Kir5.1 potassium channel with its sensitivity to pH may play an important functional role that is compromised in gliomas with low expression of this gene.

Acknowledgement: The data utilized in this study were provided by the Georgetown Database of Cancer (G-DOC®), a project of the Georgetown Lombardi Comprehensive Cancer Center designed to provide advanced translational research tools to the scientific community.

Citation Format: Marie E. Beckner. Expressions of genes for connexins and Kir5.1 differ between oligodendrogliomas and glioblastomas in patients treated with anticonvulsants [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3726.

0242 Efficient Perception-Action Coupling Relates to More Slow Wave Sleep in Military Personnel

Introduction

The ability to adapt actions to perceptions of environmental constraints, perception-action coupling, may be compromised by military operational stress (caloric restriction, sleep disruption, physical exertion). Differences in sleep may influence susceptibility to these stressors. We investigated perception-action coupling during simulated military operational stress and the influence of sleep on perception-action coupling.

Methods

During a 5-day simulated military operational stress protocol, thirty-six (6 female) service members (25.8 ± 4.7 years) completed three trials of a perception-action coupling task (PACT) in the evening after a night of baseline sleep (BASE), two nights of sleep restriction (T1) and a night of recovery sleep (T2). Participants had 8-hr for baseline and recovery sleep (2300-0700) and 4-hr disturbed sleep on sleep restriction nights (0100-0300 and 0500-0700). Polysomnography was used to determine time spent in different sleep stages: stage 2 (N2), slow wave (SWS) and rapid-eye movement (REM). The tablet-based PACT requires participants make quick, accurate perceptual judgments and responses about the ability of virtual balls to fit through virtual apertures. Linear mixed models were used to assess interaction and main effects of study day and prior sleep on PACT response time (RT) and accuracy (ACC).

Results

No significant sleep x time interactions or significant main effect of time were found for RT or ACC. A significant main effect of SWS was found for RT (F1,88.307 = 4.331, p = .04). Higher SWS was related to lower (faster) RT. No significant main effects of other sleep stages were found.

Conclusion

Perception-action coupling was maintained during simulated military operational stress. Participants with more SWS across the study responded faster during the PACT but N2 and REM sleep did not relate to perception-action coupling performance, suggesting a specific effect of SWS on perception-action coupling abilities and behaviors.

Support

Department of Defense Award #W81XWH-17-2-0070 (PI: Nindl)

A roadmap for potassium buffering/dispersion via the glial network of the CNS

Glia use multiple mechanisms to mediate potassium fluxes that support neuronal function. In addition to changes in potassium levels within synapses, these ions are dynamically dispersed through the interstitial parenchyma, perivascular spaces, leptomeninges, cerebrospinal fluid, choroid plexus, blood, vitreous, and endolymph. Neural circuits drive diversity in the glia that buffer potassium and this is reciprocal. Glia mediate buffering of potassium locally at glial-neuronal interfaces and via widespread networked connections. Control of potassium levels in the central nervous system is mediated by mechanisms operating at various loci with complexity that is difficult to model. However, major components of networked glial buffering are known. The role that potassium buffering plays in homeostasis of the CNS underlies some pathologic phenomena. An overview of potassium fluxes in the CNS is relevant for understanding consequences of pathogenic sequence variants in genes that encode potassium buffering proteins. Potassium flows in the CNS are described as follows: K1, the coordinated potassium fluxes within the astrocytic cradle around the synapse; K2, temporary storage of potassium within astrocytic processes in proposed microdomains; K3, potassium fluxes between oligodendrocytes and astrocytes; K4, potassium fluxes between astrocytes; K5, astrocytic potassium flux mediation of neurovasular coupling; K6, CSF delivery of potassium to perivascular spaces with dispersion to interstitial fluid between astrocytic endfeet; K7, astrocytic delivery of potassium to CSF and K8, choroid plexus (modified glia) regulation of potassium at the blood-CSF barrier. Components, mainly potassium channels, transporters, connexins and modulators, and the pathogenic sequence variants of their genes with the associated diseases are described.

Abstract 3940: Transformation by ENO1 highlights the positive relationship between HIF1A's and VEGFA's RNA expression levels, putatively by counteracting heterogeneity in glioblastomas

Analysis of metabolic gene expression is compromised by tumor heterogeneity. Therefore, we investigated the use of RNA expression levels from ENO1, which encodes enolase 1, to adjust for glycolytic heterogeneity within glioblastomas attributed to irregular vascularity, necrosis, surgical removal, etc. Recently, this approach revealed relationships between carbonic anhydrases and amplified oncogenes (Beckner, et al. BBA Clinical 5 (2016):1-15). Here in frozen tissue samples from 22 glioblastomas, expressions of the metabolic gene encoding hypoxia inducible factor - 1A (HIF1A) and its target, vascular endothelial growth factor A (encoded by VEGFA), were contrasted with two non-metabolic genes, i.e. those encoding platelet derived growth factor A (PDGFA) and epidermal growth factor (EGF) using RT-qPCR analysis. Genes of interest (GOI) were initially normalized with delta-delta crossing threshold methodology using housekeeping genes, ACTB and GAPDH. Then, concurrent expressions of ENO1 (ave 0.83 +/- 0.18 CI (95%), range of 0.22 - 1.97 times normal) were used to mathematically transform expressions of GOI to multiples of ENO1 to putatively correct for glycolytic variation. Expressions of PDGFA (ave 1.90 +/- 0.69 CI (95%), 0.17 - 4.01 times normal) and EGF (ave 1.25 +/- 0.57 CI (95%), 0.07 - 5.14 times normal), had correlations, r = 0.65 and 0.66, unranked (Pearson's) and ranked (Spearman's) data, respectively, among the 22 tumors. After ENO1 transformation, r = 0.68 for their unranked data & the difference in their ranges rose to 1.31-fold. Prior to ENO1 transformation, expressions of HIF1A (ave 1.33 +/- 0.28 CI (95%), 0.25 - 2.55 times normal) and VEGFA (ave 2.89 +/- 1.36 CI (95%), 0.17 - 9.94 times normal) had negative correlations, r = - 0.15 and - 0.09, unranked and ranked data, respectively. However, after transforming HIF1A and VEGFA expressions to multiples of concurrent ENO1 expression, their correlation became positive in both unranked and ranked data, with r = 0.30 for the ranked (Spearman) data. The difference in the ranges of the two metabolic genes expanded to 6.76-fold. Whereas the Wilcoxon Rank Sum of VEGFA's untransformed values, with versus without 2.02-fold elevations of HIF1A expression, was insignificant, p = 0.704, using ENO1 transformed values indicated a significant relationship, p = 0.042. Therefore, ENO1 transformation revealed the anticipated relationship between HIF1A and its target, VEGFA, at the RNA expression level that was not initially apparent in this small group of tumors. Transformation via expression levels of ENO1 compensates for glycolytic heterogeneity to reveal and highlight relationships among metabolic genes when analyzing resected tumors. Support from The Pittsburgh Foundation's Walter L. Copeland Fund for Cranial Research (D2006-0379) and the Molecular Lab, Dept. of Pathology, Univ. of Pittsburgh Medical Center.

Citation Format: Marie E. Beckner, Ian F. Pollack, Ronald L. Hamilton. Transformation by ENO1 highlights the positive relationship between HIF1A's and VEGFA's RNA expression levels, putatively by counteracting heterogeneity in glioblastomas [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 3940. doi:10.1158/1538-7445.AM2017-3940

Glioblastomas with copy number gains in EGFR and RNF139 show increased expressions of carbonic anhydrase genes transformed by ENO1

Background

Prominence of glycolysis in glioblastomas may be non-specific or a feature of oncogene-related subgroups (i.e. amplified EGFR, etc.). Relationships between amplified oncogenes and expressions of metabolic genes associated with glycolysis, directly or indirectly via pH, were therefore investigated.

Methods

Using multiplex ligation-dependent probe amplification, copy numbers (CN) of 78 oncogenes were quantified in 24 glioblastomas. Related expressions of metabolic genes encoding lactate dehydrogenases (LDHA, LDHC), carbonic anhydrases (CA3, CA12), monocarboxylate transporters (SLC16A3 or MCT4, SLC16A4 or MCT5), ATP citrate lyase (ACLY), glycogen synthase1 (GYS1), hypoxia inducible factor-1A (HIF1A), and enolase1 (ENO1) were determined in 22 by RT-qPCR. To obtain supra-glycolytic levels and adjust for heterogeneity, concurrent ENO1 expression was used to mathematically transform the expression levels of metabolic genes already normalized with delta-delta crossing threshold methodology.

Results

Positive correlations with EGFR occurred for all metabolic genes. Significant differences (Wilcoxon Rank Sum) for oncogene CN gains in tumors of at least 2.00-fold versus less than 2.00-fold occurred for EGFR with CA3's expression (p < 0.03) and for RNF139 with CA12 (p < 0.004). Increased CN of XIAP associated negatively. Tumors with less than 2.00-fold CN gains differed from those with gains for XIAP with CA12 (p < 0.05). Male gender associated with CA12 (p < 0.05).

Conclusions

Glioblastomas with CN increases in EGFR had elevated CA3 expression. Similarly, tumors with RNF149 CN gains had elevated CA12 expression.

General significance

In larger studies, subgroups of glioblastomas may emerge according to oncogene-related effects on glycolysis, such as control of pH via effects on carbonic anhydrases, with prognostic and treatment implications.

•

PCR of glioblastomas show oncogene copy numbers relate to metabolic gene expressions.

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ENO1(ENOLASE1) transformations yielded “supra-glycolytic” metabolic gene expressions.

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EGFR, RNF139, and XIAP associated with expressions of two carbonic anhydrase genes.

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Male gender associated (+) with the transformed expression of carbonic anhydrase 12.

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Oncogene amplifications may aid control of pH to protect glycolysis in glioblastomas.

Abstract 5150: Oncogene amplification in glioblastomas associates specifically with the increased expression of multiple glycolytic mediators

Although aberrant enhancement of glycolytic potential is a defining attribute of malignancy, the underlying mechanisms are complex and difficult to ascertain. A network of contributing factors is suspected to permit multiple inputs and redundancy. In this study, 79 oncogenes in glioblastomas were examined by multiplex ligation-dependent amplification (MLPA) for copy number changes to test for associations with real-time quantitative PCR expression levels of genes encoding lactate dehydrogenases (LDHA, LDHC), ATP citrate lyase (ACLY), glycogen synthase (GYS1), carbonic anhydrases (CA3, CA12), a monocarboxylate transporter (SLC16A3), hypoxia inducible factor-1A (HIF1A), and growth factors (VEGFA, PDGFA, & EGF). All were normalized to housekeeping genes and then adjusted to the level of glycolysis by division with concurrent expression of (ENO1) that encodes enolase, a key glycolytic enzyme. Tumors were separated into two groups by a cut-off of 1.10 times ENO1 to define increased and non-increased gene expression relative to glycolysis. Except for CA12 (increased in almost all tumors), expression levels yielded two groups to quantify differences in regard to the percent of tumors with amplified oncogenes. Copy numbers of oncogenes determined by MLPA to be at least 3-fold greater than normal brain DNA (tested concurrently) defined increased levels of amplification for each gene. Of the 17 amplified oncogenes (0-6 per tumor), EGFR was most frequent (11/22 tumors). The greatest difference (52%, p = 0.01) occurred between increased versus non-increased LDHC groups for tumors with amplified oncogenes. The table lists differences for each gene. Thus, amplified oncogenes associate specifically with enhanced expression levels of genes for glycolytic mediators in glioblastomas. Identification of the amplified oncogenes (EGFR &/or others) in individual tumors provides potential targets for down-regulating aberrant glycolysis in brain tumors.

Low-level amplification of oncogenes correlates inversely with age for patients with nontypical meningiomas

BACKGROUND

This study sought to identify genes in nontypical meningiomas with gains in copy number (CN) that correlate with earlier age of onset, an indicator of aggressiveness.

METHODS

Among 94 adult patients, 91 had 105 meningiomas that were histologically confirmed. World Health Organization grades I (typical), II (atypical), and III (anaplastic) were assigned to tumors in 76, 14, and 1 patient, respectively. Brain invasion indicated that two World Health Organization grade I meningiomas were biologically atypical. DNA from 15 invasive/atypical/anaplastic meningiomas and commercial normal DNA were analyzed with multiplex ligation dependent probe amplification. The CN ratios (fold differences from normal) for 78 genes were determined. The CN ratio was defined as [tumor CN]/[normal CN] for each gene to normalize results.

RESULTS

Characteristic gene losses (CN ratio < 0.75) occurred in >50% of the invasive/atypical/anaplastic meningiomas at 22q11, 1p34.2, and 1p22.1 loci. Gains (CN ratio ≥ 2.0) occurred in each tumor for 2 or more of 19 genes. Each of the 19 genes' CN ratio was ≥ 2.0 in multiple tumors, and their collective sums (up to 49.1) correlated inversely with age (r = -0.72), minus an outlier. In patients ≤ 55 versus >55 years, 5 genes (BIRC2, BRAF, MET, NRAS, and PIK3CA) individually exhibited significantly higher CN ratios (P < 0.05) or a trend for them (P < 0.09), with corrections for multiple comparisons, and their sums correlated inversely with age (r = -0.74).

CONCLUSIONS

Low levels of amplification for selected oncogenes in invasive/atypical/anaplastic meningiomas were higher in younger adults, with the CN gains potentially underlying biological aggressiveness associated with early tumor development.

Identification of ATP citrate lyase as a positive regulator of glycolytic function in glioblastomas

Glioblastomas, the most malignant type of glioma, are more glycolytic than normal brain tissue. Robust migration of glioblastoma cells has been previously demonstrated under glycolytic conditions and their pseudopodia contain increased glycolytic and decreased mitochondrial enzymes. Glycolysis is suppressed by metabolic acids, including citric acid which is excluded from mitochondria during hypoxia. We postulated that glioma cells maintain glycolysis by regulating metabolic acids, especially in their pseudopodia. The enzyme that breaks down cytosolic citric acid is ATP citrate lyase (ACLY). Our identification of increased ACLY in pseudopodia of U87 glioblastoma cells on 1D gels and immunoblots prompted investigation of ACLY gene expression in gliomas for survival data and correlation with expression of ENO1, that encodes enolase 1. Queries of the NIH's REMBRANDT brain tumor database based on Affymetrix data indicated that decreased survival correlated with increased gene expression of ACLY in gliomas. Queries of gliomas and glioblastomas found an association of upregulated ACLY and ENO1 expression by chi square for all probe sets (reporters) combined and correlation for numbers of probe sets indicating shared upregulation of these genes. Real-time quantitative PCR confirmed correlation between ACLY and ENO1 in 21 glioblastomas (p < 0.001). Inhibition of ACLY with hydroxycitrate suppressed (p < 0.05) in vitro glioblastoma cell migration, clonogenicity and brain invasion under glycolytic conditions and enhanced the suppressive effects of a Met inhibitor on cell migration. In summary, gene expression data, proteomics and functional assays support ACLY as a positive regulator of glycolysis in glioblastomas.

Abstract 1573: MLPA and REMBRANDT data predict potential modulation of vitamin D via increased CYP27B1 in aggressive primary brain tumors

Glioblastomas are lethal, aggressive primary brain tumors that resist therapies. We hypothesized that their analysis using multiplex ligation probe amplification (MLPA) kits (MRC Holland, The Netherlands) with probes for 81 genes could aid in selection of individualized treatments for patients. Genes tested in P171, P172, P173 MLPA kits are known to have increased copy numbers in various tumors. DNA was purified from 4 glioblastomas, 1 meningioma, & 1 metastatic carcinoma (lung primary). No gene amplifications were shown in the meningioma or brain metastasis. Probes detected gene amplifications in the glioblastomas: all 4 had amplified EGFR and two (50%) had additional amplifications of CDK4 and CYP27B1. One of these also had amplification of PDGFRA and MDM2. Amplification of CYP27B1 at 12q13.3 was related to CDK4 at 12q14 as shown by simultaneous occurrence in 2 of the 4 glioblastomas. Products of the amplified genes are related to cell proliferation with CYP27B1's effects indirectly mediated through its metabolism of vitamin D (not shown here). Gene amplifications in tumor samples were quantified by calculating the fold increase versus the same gene in commercial normal brain DNA tested concurrently. At least 6 other genes (no apparent changes between normal and tumor) in each MLPA kit were used for normalization between the two samples in each case. Genes amplified in at least 2 tumors, included EGFR, 6.8 − 31.5 fold, CDK4, 6.7 − 17.8 fold and CYP27B1, 3.3 − 9.7 fold increased. All were reported previously as being amplified in some glioblastomas, with a lower percent noted for CYP27B1 than here. Although survival data for copy numbers of these genes in the NIH's REMBRANDT database are limited to EGFR, survival data for their gene expressions (median reporters) are available for 297 gliomas with poorer survival indicated for increased EGFR (3-fold, p = 0.0017), CYP27B1 (2-fold, p = 0.0284) and MDM2 (2-fold, p = 0.0397) in 112, 102, and 100 patients, respectively, but not for increased expression of CDK4 or PDGFRA. Each group with poorer survival contained approximately 80% high grade gliomas, grades III-IV/IV. Chi-square analysis of REMBRANDT data confirmed the relationship between CYP27B1 and CDK4 with p = 9.04 × 10−5 for co-expression of both when increased 2-fold and p = 3.97 × 10−13 for 2-fold increased CYP27B1 with 3-fold increased CDK4. Analysis of CYP27B1 should be included in genomic surveys of brain tumors performed for designing individualized treatments in that vitamin D levels are potentially modulated due to amplification of the gene encoding one of its metabolic enzymes. We acknowledge Louisiana State University Health Sciences Center - Shreveport's Fall 2008 Grant-In-Aid funding, Dwain D'Souza, LSUHSC-S, for technical support and use of the Repository of Molecular Brain Neoplasia Database (REMBRANDT) at NCI & NINDS at NIH, http://rembrandt.nci.nih.gov.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1573.

Tumor cells from ultrasonic aspirations of glioblastomas migrate and form spheres with radial outgrowth

Studies of primary cells from malignant brain tumors such as glioblastomas are limited by the small size of surgically resected specimens. However, glioblastomas are also frequently debulked via ultrasonic aspiration. In this study, we examined the functional competence and growth of their aspirated cells. Cells from minced tissue and aspirations were comparable in migration, formation of pseudopodia, development of cellular spheres with radial outgrowth, and neuroectodermal features. Cultures were maintained for more than six weeks without fibroblastic overgrowth. Our observations show that ultrasonically aspirated specimens contain cells useful for studies of tumor migration and growth of tumorspheres.

Albumin marks pseudopodia of astrocytoma cells responding to hepatocyte growth factor or serum

It is well accepted that dysfunction in the blood brain barrier (BBB) allows permeation of albumin from the bloodstream into astrocytic brain tumors, especially glioblastomas, the most aggressive astrocytomas. In vitro, bovine serum albumin (BSA) aids functional cell assays by maintaining cytokines and growth factors in solution and delivering its cargo of fatty acids. Earlier, we showed that BSA was prominent in lysates prepared from pseudopodia formed by U87 astrocytoma cells. The present studies investigated the association of albumin with pseudopodia formed by U87 and LN229 astrocytoma cells. With hepatocyte growth factor (HGF) stimulation, cell migration was enhanced and BSA, especially its dimerized form, was prominent in pseudopodia compared to unmigrated cells on one-dimensional gels and immunoblots. When lysates were equalized for levels of glyceraldehyde-3-phosphate dehydrogenase, the rise for BSA levels in pseudopodia vs migrated cells was comparable or greater than levels noted for established pseudopodial proteins, beta-actin and ezrin. The increase for dimerized BSA in pseudopodia compared to unmigrated cells was greater than the rise in levels of beta-actin, ezrin, HGF, and phosphorylated Met when pseudopodia were harvested from filters with 1 mum pores using either cell line. Fluorescein (F)-labeled BSA co-localized with HGF on actin-rich cellular protrusions and with CM-DiI labeled pseudopodial plasma membranes. The F-BSA highlighted small, individual pseudopodial profiles more so than complex pseudopodial networks (reticulopodia) or unmigrated cells. Labeled human serum albumin also decorated pseudopodia preferentially. Albumin's association with pseudopodia may help to explain its selective accumulation in astrocytomas in vivo. The leaky BBB permits serum albumin to enter the microenvironment of astrocytomas thus allowing their invasive cells contact with serum albumin as a source of fatty acids that would be useful for remodeling cell membranes in pseudopodia. Thus, albumin potentially aids and marks invasion as it accumulates in these tumors.

Glycolytic glioma cells with active glycogen synthase are sensitive to PTEN and inhibitors of PI3K and gluconeogenesis

Increased glycolysis is characteristic of malignancy. Previously, with a mitochondrial inhibitor, we demonstrated that glycolytic ATP production was sufficient to support migration of melanoma cells. Recently, we found that glycolytic enzymes were abundant and some were increased in pseudopodia formed by U87 glioma (astrocytoma) cells. In this study, we examined cell migration, adhesion (a step in migration), and Matrigel invasion of U87 and LN229 glioma cells when their mitochondria were inhibited with sodium azide or limited by 1% O(2). Cell migration, adhesion, and invasion were comparable, with and without mitochondrial inhibition. Upon discovering that glycolysis alone can support glioma cell migration, unique features of glucose metabolism in astrocytic cells were investigated. The ability of astrocytic cells to remove lactate, the inhibitor of glycolysis, via gluconeogenesis and incorporation into glycogen led to consideration of supportive genetic mutations. Loss of phosphatase and tensin homolog (PTEN) releases glycogenesis from constitutive inhibition by glycogen synthase kinase-3 (GSK3). We hypothesize that glycolysis in gliomas can support invasive migration, especially when aided by loss of PTEN's regulation on the phosphatidylinositol-3 kinase (PI3K)/Akt pathway leading to inhibition of GSK3. Migration of PTEN-mutated U87 cells was studied for release of extracellular lactic acid and support by gluconeogenesis, loss of PTEN, and active PI3K. Lactic acid levels plateaued and phosphorylation changes confirmed activation of the PI3K/Akt pathway and glycogen synthase when cells relied only on glycolysis. Glycolytic U87 cell migration and phosphorylation of GSK3 were inhibited by PTEN transfection. Glycolytic migration was also suppressed by inhibiting PI3K and gluconeogenesis with wortmannin and metformin, respectively. These findings confirm that glycolytic glioma cells can migrate invasively and that the loss of PTEN is supportive, with activated glycogenic potential included among the relevant downstream effects.

Proteomic characterization of harvested pseudopodia with differential gel electrophoresis and specific antibodies

Malignant gliomas (astrocytomas) are lethal tumors that invade the brain. Invasive cell migration is initiated by extension of pseudopodia into interstitial spaces. In this study, U87 glioma cells formed pseudopodia in vitro as cells pushed through 3 microm pores of polycarbonate membranes. Harvesting pseudopodia in a novel two-step method provided material for proteomic analysis. Differences in the protein profiles of pseudopodia and whole cells were found using differential gel electrophoresis (DIGE) and immunoblotting. Proteins from two-dimensional (2D) gels with M(R)'s of 20-100 kDa and pI's of 3.0-10.0 were identified by peptide mass fingerprinting analysis using mass spectrometry. For DIGE, lysates of pseudopodia and whole cells were each labeled with electrophilic forms of fluorescent dyes, Cy3 or Cy5, and analyzed as mixtures. Analysis was repeated with reciprocal labeling. Differences in protein distributions were detected by manual inspection and computer analysis. Topographical digital maps of the scanned gels were used for algorithmic spot matching, normalization of background, quantifying spot differences, and elimination of artifacts. Pseudopodial proteins in Coomassie-stained 2D gels included isoforms of glycolytic enzymes as the largest group, seven of 24 proteins. Peptide mass fingerprint analysis of DIGE gels demonstrated increased isoforms of annexin (Anx) I, AnxII, enolase, pyruvate kinase, and aldolase, and decreased mitochondrial manganese superoxide dismutase and transketolase in pseudopodia. Specific antibodies showed restricted immunoreactivity of the hepatocyte growth factor (HGF) alpha chain to pseudopodia, indicating localization of its active form. Met (the HGF receptor), actin, and total AnxI were increased in pseudopodial lysates on immunoblots. Increased constituents of the pseudopodial proteome in glioma cells, identified in this study as actin, HGF, Met, and isoforms of AnxI, AnxII, and several glycolytic enzymes, represent therapeutic targets to consider for suppression of tumor invasion.

Loss of heterozygosity reveals non-VHL allelic loss in hemangioblastomas at 22q13

Hemangioblastomas (HBs) are low-grade (World Health Organization grade I/IV) central nervous system (CNS) tumors that frequently contain VHL (3p26) mutations. They occur sporadically and in von Hippel Lindau (VHL) disease. Encoded pVHL aids degradation of hypoxia-inducible factors (HIFs) in the presence of normal oxygen levels. HBs provide an in vivo view of HIF effects within a CNS tumor. Typically, HBs are cystic tumors containing a mural nodule formed by noninvasive, vacuolated stromal cells that are embedded in a network of capillaries. Nine HBs, consecutively resected from 8 patients at our institution during a recent 2-year time span, were evaluated for additional losses of tumor suppressor genes. Non-VHL microsatellites studied for loss of heterozygosity (LOH) are near tumor suppressor genes lost in gliomas, pituitary adenomas, several CNS tumors on 22q, neurofibromatosis 1, and colon carcinomas (13, 2, 2, 1, and 2 markers for each, respectively). LOH in the region of 3p21.3-3p26.3 occurred in 3 of 8 HBs informative for at least 1 marker (D3S1539, D3S2303, or D3S2373). By using 2 markers (D22S417 and D22S532) for 22q13.2, LOH was found in 5 of 8 informative HBs. All 3 HBs with allelic losses near VHL also showed LOH at 22q13.2. No consistent losses were found with markers for 1p34, LMYC, 5q21, 5q32, 9p21, 10q23, 17p13, and 19q13. LOH for the 22q13.2 region in HBs suggests that the loss of another tumor suppressor gene is involved in the pathogenesis of HBs in addition to VHL. Absence of LOH for glioma markers is consistent with the low-grade behavior of HBs.

Giant cell tumor of the skull: a case report and review of the literature

BACKGROUND

Giant cell tumors are benign lesions that typically occur at the epiphyses of long bones that typically present with pain or swelling. Most data on giant cell tumors in the skull consist of case reports, and many large series of giant cell tumors have no examples in the skull.

METHODS

We report a case of giant cell tumor of the skull and review the literature on these lesions.

RESULTS

A 24-year-old woman presented with localized tenderness and mild swelling over the left inferior parietal and occipital bones. She was neurologically intact with a nonmobile, tender, palpable mass over the left subocciptal area. A computed tomography (CT) scan showed a radiolucent, expansile, lytic lesion involving the left occipital bone. The patient underwent a left occipital craniectomy with resection of the bone and epidural mass. Permanent histopathologic sections and immunostains revealed a giant cell tumor.

CONCLUSIONS

Giant cell tumors are generally benign, locally aggressive lesions for which surgical excision is the treatment of choice. This report contributes to the scarce literature on these tumors in the skull.

Intracranial extramedullary hematopoiesis associated with pilocytic astrocytoma: a case report

Intracranial EMH is only occasionally found in primary brain tumors (mostly hemangioblastomas) and, to our knowledge, this is the first case of EMH associated with an astrocytoma. Intracranial extramedullary hematopoiesis (EMH) is described in a 29-year-old man with a recurrent pilocytic astrocytoma in the tectal region. Special stains confirmed the identities of erythroid, myeloid and megakaryocytic cells. The patient had no evidence of a predisposing bone marrow disorder or systemic EMH. Although the presence of multinucleated and blastic cells associated with a low-grade brain neoplasm is unusual, recognition of hematopoietic lineages allows EMH to be readily identified. Another tumor resection after a year of follow-up confirmed the absence of malignant progression in this recurrent astrocytoma. The small number of cases describing intracranial EMH in the absence of systemic hematologic abnormalities are correlated with the findings in this case. The low incidence of intracranial EMH indicates that cells with hematopoietic potential are seldom exposed to a supportive microenvironment within the central nervous system. However, intracranial EMH should be included as a potential, ancillary diagnosis when considering brain lesions. This may be particularly true if medical therapies involving growth factors or stem cells are found to promote hematopoiesis.

Extracellular angio-associated migratory cell protein plays a positive role in angiogenesis and is regulated by astrocytes in coculture

The extracellular form of angio-associated migratory cell protein (AAMP), a recently discovered protein, plays a positive role in angiogenesis and can be regulated by astrocytes. Angiogenic activities are inhibited by an affinity-purified, polyclonal antibody generated to recombinant AAMP. Inhibition of endothelial cell tube formation was previously shown and now endothelial cell migration assays using this antibody show dose-dependent inhibition (75%) of endothelial cell migration. Also, antisense inhibition has been used to determine the effects of reducing total AAMP (extracellular and intracellular forms). An AAMP-specific antisense oligonucleotide that targets a region near its amino terminus, anti-MES, inhibits (45%) total AAMP production by bovine aortic endothelial cells (BAECs), compared to a negative control oligonucleotide. Paradoxically, comparable use of antisense-MES results in a 27% increase in BAEC motility. Decreased cellular production of total AAMP (via antisense) that results in an increase of endothelial migration contrasts with antibody inhibition of extracellular AAMP that decreases migration. This indicates compartment-specific roles for AAMP in angiogenesis. Transwell cocultures of human astrocytes and BAECs increase (53%) the amount of extracellular AAMP found associated with endothelial cells. Therefore, regulation of extracellular AAMP by astrocytes is hypothesized to aid in angiogenesis of the nervous system. Extracellular AAMP's positive role may be either as a promoter or as a permissive protein in this process.

AAMP, a conserved protein with immunoglobulin and WD40 domains, regulates endothelial tube formation in vitro

Angio-associated migratory cell protein (AAMP) is a newly discovered protein that is widely distributed with strong expression in endothelial cells and others with migratory potential (cytotrophoblasts, carcinoma cells, etc). AAMP is 52 kd with an isoelectric point of 5.2. Its sequence contains immunoglobulin type domains, WD40 repeats, a large acidic region with an acid box, a potential transmembrane region, potential serine/threonine phosphorylation sites, and a positively charged amino-terminal region with strong heparin binding potential (Kd = 14 pmol). Human umbilical vein endothelial cells cultured on Matrigel, a basement membrane material, form endothelial tubes (capillary-like structures). Anti-recombinant AAMP (anti-rAAMP) (1 to 10 microg/ml) inhibits this process under conditions that favor cross-linking of its ligand (AAMP). Immunofluorescent staining has shown that AAMP is distributed both intracellularly and extracellularly in cultures of endothelial cells and tubes. Molecular analysis of AAMP's protein sequence shows a striking evolutionary relationship with the YCR072c protein in Saccharomyces cerevisiae. Both the human and yeast proteins show an unusual and almost identical arrangement of immunoglobulin type domains, WD40 repeats, a protein kinase C phosphorylation consensus site in the carboxyl region, and a positively charged amino-terminal region that in AAMP has heparin binding potential. Detection of YCR072c's immunoglobulin type domains is new. Thus, AAMP is a protein that has been highly conserved in evolution and may function in the regulation of endothelial tube formation.

AAMP, a newly identified protein, shares a common epitope with alpha-actinin and a fast skeletal muscle fiber protein

AAMP (angio-associated migratory cell protein) shares a common epitope with alpha-actinin and a fast-twitch skeletal muscle fiber protein. An antigenic peptide, P189, derived from the sequence of AAMP was synthesized. Polyclonal antibodies generated to P189 readily react with AAMP (52 kDa) in brain and activated T lymphocyte lysates, alpha-actinin (100 kDa) in all tissues tested, and a 23-kDa protein in skeletal muscle lysates. The antibody's reactivity for alpha-actinin can be competed with the purified protein. Activation of T lymphocytes does not alter the degree of alpha-actinin reactivity with anti-P189 as it does for AAMP's reactivity in these lysates. Competition studies with peptide variants show that six amino acid residues, ESESES, constitute a common epitope in all three proteins in human tissues. The antigenic determinant is continuous in AAMP but discontinuous (or assembled) in alpha-actinin. alpha-Actinin does not contain this epitope in its linear sequence so reactivity is attributed to an epitope formed by its secondary structure. Limited digestion of the reactive proteins with thermolysin destroys anti-P189's reactivity for alpha-actinin while reactivity for recombinant AAMP is retained. Specificity of anti-P189 for human skeletal muscle fast fibers seen on immunoperoxidase staining may be explained by anti-P189's reactivity with a 23-kDa protein found only in skeletal muscle lysates. Its pattern of reactivity is the same as that obtained using monoclonal anti-skeletal muscle myosin heavy chain in type II (fast-twitch) fibers.

Identification of a new immunoglobulin superfamily protein expressed in blood vessels with a heparin-binding consensus sequence

A novel immunoglobulin-type protein expressed in blood vessels has been identified. The cDNA for AAMP (angio-associated, migratory cell protein) was first isolated from a human melanoma cell line during a search for motility-associated cell surface proteins. Upon analysis of the tissue distribution of AAMP, it was found to be expressed strongly in endothelial cells, cytotrophoblasts, and poorly differentiated colon adenocarcinoma cells found in lymphatics. The sequence of AAMP predicts a protein (M(r) 49,000) with distant identity (25%) to known proteins. It contains immunoglobulin-like domains [one with multiple homologies to deleted in colon carcinoma (DCC) protein], the WD40 repeat motif, and a heparin-binding consensus sequence. A 1.6-kilobase mRNA transcript of AAMP is detected in tissue culture cell lines and tissues. Affinity-purified polyclonal antibodies, anti-recombinant AAMP, and anti-peptide 189 (AAMP derived) recognize a M(r) 52,000 protein in human tissue and cellular extracts. The protein size is in keeping with the mRNA and predicted sequence. The AAMP-derived peptide, P189, contains a heparin-binding domain (dissociation constant, 14 pmol) and mediates heparin-sensitive cell adhesion. The shared expression of AAMP in endothelial cells, trophoblasts, and tumor cells implies a common function in migrating cells.

Oxyphilic papillary thyroid carcinomas

Oxyphilic papillary carcinomas of the thyroid have not been extensively studied because they are rare. The morphology and behavior of 34 cases were described. The average age was 44.1 years, the female-to-male ratio was 3.9:1, and the average diameter of the tumors was 2.3 cm. All had papillary structures present. In 31 cases, there was capsular or parenchymal invasion. Six cancers had local lymph node metastases. The average follow-up for 29 patients was 8.1 years. Tumors reappeared in four patients; one patient died from recurrent disease, one patient with disease died due to an unrelated carcinoma, and two patients were treated successfully. Twenty-seven patients at the end of follow-up were alive with no detectable thyroid cancer. The majority of patients remained free of tumor, especially those younger than 50 years.

Tumor cell motility

Tumor cell motility is required for invasion and metastasis. The locomotory machinery of the cell includes cell projections called pseudopodia which are regulated by a complicated linkage between cell surface receptors or sensors and the internal cytoskeleton. Recently a new class of motility stimulating cytokines have been identified. These cytokines can function as autocrine motility factors and require a pertussis toxin sensitive G protein pathway to transduce a random motile response.

Cell motility, a principal requirement for metastasis

In studying the role of motility in the metastasis of tumor cells, we have described an autocrine motility factor. This agent, which stimulates random motility, probably contributes to the initial dissociation of the cells from the primary tumor mass. Extracellular matrix components, via several different mechanisms, may facilitate the crossing of biological barriers by the cells prior to the entry into the circulation. In locating at new sites, the tumor cells may be induced to exit from the circulation in response to attractants such as IGFs that could emanate from the target organ. These same growth factors could then stimulate cellular proliferation for another metastatic cycle. It is quite probable that detection of AMF may provide a new tool in cancer diagnosis. The complete characterization of AMF may also yield valuable therapeutic approaches: design of low molecular size antagonists of the attractants and antibodies that might be effective therapeutically as well as diagnostically. It seems clear, in any event, that immobilizing the tumor cell may be a crucial step in inhibiting metastasis.

Glycolysis as primary energy source in tumor cell chemotaxis

The energy requirements via glycolytic pathways were directly measured in migrating tumor cells. Motility in the metastatic human melanoma cell line A2058, stimulated by insulinlike growth factor I (IGF-I), depends on glycolysis in the presence of glucose as its principal source of energy. Motility in glucose-free medium was 75% reduced and utilized mitochondrial respiration (inhibited by oligomycin). With increasing (physiologic) glucose concentrations, there was a dramatic shift to anaerobic glycolysis as the energy source and 93% elimination of the oligomycin inhibition of motility. Oxamate, an inhibitor of glycolysis, inhibited motility at all glucose concentrations. CO2 production from glycolysis and from the hexose monophosphate shunt was measured in migrating tumor cells. The time course and glucose-dose dependence of glycolytic CO2 production correlated directly with motility. In contrast, mitochondrial CO2 production was inversely related to glucose concentration. A monoclonal antibody for the IGF-I receptor inhibited both motility and glycolytic CO2 production, indicating that both processes are receptor mediated.

Solid and cystic ultimobranchial body remnants in the thyroid

In this study we determined the incidence rate (89%) and characterized the morphology of ultimobranchial body (UBB) remnants found in 18 serially sectioned neonatal thyroid glands. Although UBB remnants are often referred to as solid cell nests, we found cystic features in 55%. Ciliated columnar cells were seen in 23%. One contained a large pseudo-papilla. The UBB cells had nuclei with features reminiscent of papillary carcinoma nuclei in that they were enlarged, oval, and contained finely dispersed chromatin when compared with follicular cell nuclei. Both papillary carcinomas and UBB remnants are common, occur as tiny, solid, or cystic thyroid entities in patients of all ages, may contain papillary structures, and share some common nuclear features. Therefore, it is important to include UBB remnants in the differential diagnosis of minute thyroid entities and to recognize their morphologic features.

Mitochondrial adenosine triphosphatase in the oxyphil cells of a renal oncocytoma

Oxyphil cells are characterized by cytoplasm packed with large numbers of mitochondria. Study of these unusual cells may provide information about the regulation of mitochondrial biogenesis. Although it has been suggested that this is a compensatory proliferation due to a mitochondrial dysfunction, no such dysfunction has been well documented. In this study we considered the possibility of dysfunction in the mitochondrial enzyme F1/Fo-adenosine triphosphatase(ATPase) as a stimulating factor involved in the mitochondrial proliferation of oxyphil cells. Mitochondria isolated from frozen tissue of a renal oncocytoma showing structural integrity and purity by electron microscopy were studied. Submitochondrial particles formed by sonic disruption showed the presence of the F1 component of mitochondrial ATPase with electron microscopy which was functionally active. The oligomycinsensitive ATPase activity from the renal oncocytoma was 0.133 mumol/min.mg submitochondrial particle protein which was higher than the readings obtained from normal kidney tissue (0.091 mumol/min.mg SMP protein) obtained from hamsters. Normal human renal tissue obtained at autopsy contained only nonfunctional mitochondria and therefore could not be used as control tissue. Mitochondrial ATPase dysfunction does not appear to be the inciting factor in the proliferation of mitochondria seen in oxyphil cell metaplasia and future studies should consider other possibilities. Preliminary functional studies of this nature can be performed with properly prepared frozen surgical tissue.

Cytologic diagnosis and ultrastructure of fine-needle aspirates of ganglion cysts

This report describes 28 ganglion cysts in 21 patients. The presence of a colorless to pale-yellow gelatinous material in the aspirate is pathognomonic of ganglion cyst. The smears are fairly monotonous, and show abundant mucoid material, single cells resembling histiocytes, a few tight clusters of cells, some collagen fibers, and some red blood cells with altered shapes. Ultrastructural studies performed on five specimens reveal the fibroblastic and/or histiocytic nature of the cells in the aspirates.