Abstract B16: Evaluation of LDH inhibition as a treatment strategy in Ewing sarcoma

Long-term outcomes for patients with relapsed, recurrent, or metastatic Ewing sarcoma (ES) remain poor despite advances in multimodal chemotherapy and local tumor control. The discovery of new targets and novel therapies is therefore critical to improving care for these patients. Recent insights into the metabolic landscape of ES have revealed that the EWS/FLI1 fusion oncoprotein regulates metabolic pathways in this disease, including shifting glucose consumption away from oxidative metabolism and towards glycolysis, a pathway that relies on LDH. Targeting this increased dependence on glycolysis presents an opportunity to inhibit the growth of ES cells through a novel therapeutic approach, while potentially limiting the toxicity delivered to normal cells. We therefore sought to evaluate the activity of NCGC-737 and NCGC-006, two novel LDHA/B inhibitors identified and validated as part of the Experimental Therapeutics Program of the National Cancer Institute (NCI-NExT), in ES.

For in vitro studies, proliferation of ES cells lines was assessed after inhibition of LDHA/B by each agent using IncuCyte and MTS assays. Protein expression of phospho- and total LDH was evaluated by Western blot. LDH activity was assessed using the pyruvate-dependent oxidation of NADH. NAD/NADH levels were determined using NAD/NADH-Glo. Analysis of glycolytic profiles was performed using the Agilent Extracellular Flux Analyzer. For in vivo studies, female SCID mice underwent orthotopic injection of ES cells from established cell lines. When tumors reached a desired size, mice were randomized and then treated on a variety of dosing schedules. Toxicity assessments included evaluation of overall appearance, weekly weights, blood sampling, and full necropsies on selected mice. Tumors were measured twice per week for assessment of efficacy. Tumors were harvested at midpoints and at study endpoint for assessments of drug level, target inhibition, and biology.

ES cell lines displayed varying sensitivity to NCGC-737 and NCGC-006, with IC-50 values ranging from 50 nM to 500 nM. While protein expression of phospho-LDH, total LDH-A, and total LDH-B were not correlated with sensitivity to either agent, glycolytic profiles were predictive of sensitivity. Cell lines that underwent a greater reduction in glycolytic capacity (the change in ECAR measured before and after oligomycin treatment) after LDHA/B inhibition experienced a greater antiproliferative effect, while cell lines that were able to maintain glycolytic capacity despite LDHA/B inhibition exhibited less of an effect on growth. In vivo studies to describe the toxicity of these agents demonstrated that hemolysis was the primary dose-limiting toxicity, and was dose dependent. Additional toxicity studies of specific tissues are ongoing and will be reported. Preliminary in vivo studies to optimize dosing regimen established that compared to oral dosing, intravenous dosing resulted in higher and more consistent tumor drug levels and improved target inhibition, with up to 93% of intratumoral LDH activity inhibited. Efficacy studies are ongoing and will be reported.

Preclinical data suggest that inhibition of LDHA/B may represent a potentially novel therapeutic strategy in the treatment of ES.

Citation Format: Christine M. Heske, Anna E. Gibson, Josh T. Baumgart, Choh Yeung, Sameer H. Issaq, A Mendoza, Michelle S. Johnson, Guiseppe L. Squadrito, Lillian Culp, Victor M. Darley-Usmar, Len M. Neckers. Evaluation of LDH inhibition as a treatment strategy in Ewing sarcoma [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B16.

Topological and quantitative-analyses of early events in tumor-formation using histochemically-tagged transformed 3t3 cells

Human EJ H-ras or c-sis oncogene-transformed Balb/c 3T3 cells were investigated to discern the oncogene dependence of earliest events of primary tumor development by utilizing bacterial lacZ or human alkaline phosphatase histochemical marker genes. The locations and morphologies of transformed or untransformed Balb/c 3T3 cells, also transfected with either marker gene, were monitored in situ by visual, histochemical staining of skin after subcutaneous injection. Cell numbers remaining in the subcutaneous space were quantitated through newly-developed assays maximizing enzymatic detection of the transfected marker gene-encoded enzymes using luminescent substrates. Either oncogene was effective at facilitating cell establishment within the subcutaneous space while parental 3T3 cells were cleared efficiently. Quantitation by enzymatic assays revealed that the rates of cell loss and establishment differed for the two transformants. Ras-transformed cells exhibited a spindled-shaped morphology within the subcutis. In contrast, sis-transformed cells established a dichotomous morphology, with one subpopulation spreading modestly and another remaining rounded. 3T3 cells which established transiently became well-spread in a manner reminiscent of cells in culture. In conclusion, ras and sis oncogenes aid the parental 3T3 cells to overcome the clearance mechanisms at the subcutaneous injection site and modify 3T3 cell morphology as visualized in situ.

Upregulation of CD44s in c-sis-transformed balb/c 3T3 cells by autocrine growth factor mechanisms, including PDGF

Regulation of CD44s by the c-sis oncogene product was investigated. Both CD44s protein and mRNA were comparably upregulated, consistent with some degree of transcriptional regulation; its ligand binding was also activated in confluent but not in sparse cultures of sis-transformed Balb/c 3T3 cells. CD44s was also elevated in confluent cultures of parental 3T3 cells treated with conditioned media from confluent c-sis transformants (but not from 3T3 cells); these media (but not media from ras transformants or parental 3T3 cells) contained platelet-derived growth factor (PDGF)-immunoreactive material. CD44s upregulation by these media could be partially blocked by anti-PDGF antibodies. These media also induced activation via tyrosine autophosphorylation and activation-dependent downregulation of PDGF beta-receptors. sis-transformed 3T3 cells contained low levels of PDGF receptor, but CD44 levels could still be increased in these cells by addition of PDGF. These results suggest that CD44s is upregulated in confluent cultures of c-sis-transformed cells by autocrine growth factors, including PDGF, secreted into the cell's microenvironment.

Diagnosis and treatment planning for ceramic restorations

Esthetic dentistry's intention is to deliver all phases of dentistry in a natural and attractive manner. Whether restorative and laboratory procedures or periodontal, orthodontic, or surgical procedures, ultimately the end results need to be natural in appearance and esthetically pleasing to the patient and dentist. The intention of this case study was to emphasize the relationship between the patient, dentist, and laboratory technician. The ability of all three to work efficiently demands incredible communication skills. A mutual respect in knowledge, desires, and skills creates the foundation to initiate this relationship. Communication skills and respect need to follow time-tested principles of restorative and prosthetic dentistry to be successful.

Overexpression of the oncofetal Fn variant containing the EDA splice-in segment in the dermal-epidermal junction of psoriatic uninvolved skin

The extracellular matrix protein, Fn, has critical functions in cell attachment, migration, differentiation, and proliferation. We have previously shown that fibronectin (Fn) is abnormally expressed and potentiates entry into the cell cycle of basal keratinocytes in uninvolved psoriatic skin, in combination with T cell lymphokines. It is not known what type of Fn is present in psoriatic skin, however, and how this Fn may regulate signaling. Embryonic forms of cellular Fn containing extra domains, designated EDA and EDB, are generated by alternative splicing and are seen in proliferating, developing tissue and in wound healing. Because the EDA segment enhances the integrin binding sequence Arg, Gly, Asp (RGD), which, when present, has been shown to be critical in integrin-extracellular matrix signaling, we were particularly interested in determining whether or not EDA-containing Fn (EDA+Fn) represented the aberrantly expressed Fn in psoriasis. Increased EDA+ Fn protein was demonstrated by immunostaining at the dermal-epidermal junction in clinically uninvolved skin from six of six patients with psoriasis, but not in skin from control subjects. Using reverse transcription polymerase chain reaction an increased ratio of EDA+ Fn versus EDA- Fn mRNA was present in epidermal samples from psoriatic but not control individuals. Interestingly, the EDA+Fn in the psoriatic epidermis had the IIICS region spliced out (EDA+, FDB-, IIICS-, III9+), which was shared with normal epidermis (EDA-, EDB-, IIICS-, III9+). These results suggest a selective predominance of the EDA+ Fn isoform at the dermal-epidermal junction of psoriatic skin. The consistent aberrant localization of EDA+ Fn at the dermal-epidermal junction in uninvolved skin of psoriatics may confer the hyperresponsiveness of psoriatic uninvolved basal keratinocytes for rapid cellular proliferation in response to T cell signals. Key words: immunohistochemistry/integrin/keratinocyte/RT-PCR.

Empress 2. First year clinical results

As the search for perfect dental restorative materials continues, it seems we routinely return to ceramics as our standard. Current all-ceramic systems are state-of-the-art with regard to esthetics and function, but are limited in use to single unit restorations. Recently, an all-ceramic lithium disilicate-fluorapatite ceramic system was introduced (IPS Empress 2, Ivoclar North America, Amherst, NY), that allows multiple unit restorations to be fabricated and cemented using adhesive or traditional cementation techniques. This article will overview the technical procedures and advantages of this new ceramic system.

IPS Empress veneers. Color communication, laboratory fabrication, and cementation

Once considered to be revolutionary, porcelain veneers are now the foundation of most aesthetic dental practices. Requiring only conservative preparations, porcelain veneers can dramatically change a smile. This article discusses the technique necessary to prepare and place porcelain veneers, using a new pressed-ceramic system. Close and thorough cooperation and communication between the clinician and the laboratory are essential throughout the procedure, and this article is coauthored by a dentist and a ceramist.

Persistent alpha 1 integrin subunit expression in human neuroblastoma cell lines which overexpress N-myc and downregulate other integrin subunits

Neuroblastoma is characterized by amplification and overexpression of N-myc. N-myc down-regulates expression of the beta 1 integrin extracellular matrix receptor, however, some beta 1 was found on the surface of N-myc overexpressing neuroblastoma cell lines. It was determined that the alpha 1 subunit is expressed in the cells, associates with beta 1 and is present on the cell surface. Interestingly, the level of alpha 1 was reduced marginally when compared to beta 1. Finally, overexpression of N-myc alters cell morphology on extracellular matrix proteins with persistence of alpha 1 beta 1-dependent responses. Our work supports the conclusion that altered integrin expression may be an important factor in human neuroblastoma.

Science, art and nature: a case report

The ceramo-metal restoration still forms the backbone of modern restorative dentistry, despite many new systems. This article discusses a unique ceramo-metal system, its advantages, and clinical and technical applications teamwork between the dentist and the technician is emphasized. IPS Classic (Ivoclar Williams) is a ceramic system with several exclusive features. It encompasses Color Visions, a computer-generated shade system, and the IPS Impulse modifier system allows the ceramist unlimited creativity in color development.

Negative regulation of fibronectin gene-transcription by ej-ha-ras and C-sis oncogenes in BALB/c 3t3 cells

Down-regulation of fibronectin gene expression at cell surfaces by various oncogenes is an important phenotypic change of many transformed cells. Mechanisms effecting this loss of cell surface fibronectin remain poorly understood. An isogenic mouse fibroblast system, Balb/c 3T3, was used to investigate the effect of oncogene transformation on fibronectin gene transcription. Fibronectin mRNA levels were shown to decrease by >80% when 3T3 cells became stably transformed by EJ-Ha-ras or c-sis oncogenes. The mouse fibronectin gene promoter was subsequently cloned from a mouse genomic library and inserted into reporter gene constructs. Transient transfection assays with the 1.2 kb fibronectin promoter demonstrated that its activity was also decreased in the two transformed cell lines to a similar extent as fibronectin mRNA levels. Co-transfections into 3T3 cells with both the promoter construct and either Ha-ras or c-sis expression constructs provided further support for negative regulation of fibronectin gene transcription by oncogene expression. Potential mechanisms for such transcriptional regulation are proposed based on deletion analysis of the fibronectin promoter. These data suggest that down-regulation of fibronectin gene transcription can contribute directly to the loss of cell surface fibronectin in transformed murine fibroblasts.

Color communication, laboratory fabrication, and cementation

Once considered to be revolutionary, porcelain veneers are now the foundation of most aesthetic dental practices. Requiring only conservative preparations, porcelain veneers can dramatically change a smile. This article discusses the technique necessary to prepare and place porcelain veneers, using a new pressed-ceramic system. Close and thorough cooperation and communication between the clinician and the laboratory are essential throughout the procedure, and this article is coauthored by a dentist and a ceramist.

The effect of immunoglobulin occurring on human sperm in vivo on the human sperm/hamster ova penetration assay

We selected 91 infertile men who were tested for increased sperm-associated immunoglobulin and also tested in the human sperm/hamster ova penetration assay. There was a statistically significant association between the presence of increased sperm-associated IgG alone (p = 0.0218) and both sperm-associated IgG and A (p = 0.0187) when correlated with the failure to penetrate any hamster ova. There was a trend but no statistical significance when sperm-associated immunoglobulin A alone was present. There was a trend but no statistical relationship between the presence of sperm-associated immunoglobulin and the sperm penetration assay when the criteria for normality of the sperm penetration assay was a 15% or greater ovum penetration rate.

The effect of freezing on sperm-associated immunoglobulin G (IgG)

Previously frozen and fresh sperm from infertile and fertile men were assayed for sperm-associated immunoglobulin G (IgG) to determine the effect of a simple freezing technique on the assay results. A direct radiolabeled antiglobulin assay (DRAA) and a direct fluorescein-labeled antiglobulin assay (DFAA) utilizing a fluorescein-activated flow cytometer were employed. The amount of IgG detected by the DRAA and the percentage of sperm that fluoresced in the DFAA generally declined when frozen sperm were used, but only the DFAA showed a statistically significant decrease. However, the degree of decline was predictable (r = 0.91 in both assays), and whether the test remained positive or negative when frozen sperm were used was not significantly affected.

Sorting out of normal and virus-transformed cells in cellular aggregates

The sorting-out behavior (self-segregation of two cell types from mixtures of the two) of five different established cell lines was studied. Eight of the ten possible binary combinations of these lines, cultured as cellular aggregates, were examined. Mouse BALB/c 3T3 cells sorted out internally to the corresponding malignant SV40 virus-transformed 3T3 cells. The transformed 3T3 line (SVT-2) did not sort out from a revertant line selected from SVT-2 cells by resistance to concanavalin A (con A). The revertant cells sorted out externally to the parent BALB/c 3T3 cells, although segregation was generally incomplete. BALB/c 3T3 cells did not sort out from another contact-inhibited line of 3T3 cells derived from Swiss albino mice (Swiss 3T3). Both BALB/c 3T3 and Swiss 3T3 cells sorted out from cells of the contact-inhibited hamster line, NIL B. Instead of a two-layered sphere, however, a three-layered structure was observed with most of the NIL B cells external to the 3T3 cells, and a few NIL B cells comprising the center of the sphere. On the other hand, NIL B cells did not consistently sort out from either the SVT-2 or con A cells. In general, sorting out between pairs of these five lines are slower and less complete than is generally observed between the more extensively studied chick embryonic tissue cells, suggesting that the cultured cells may be more closely related in their adhesive properties. The internal segregation of BALB/c 3T3 cells relative to SVT-2 cells is consistent with the hypothesis that transformed cells are less adhesive than their nontransformed counterparts.