Publications by authors named "Elena Ostroumov"

6 Publications

  • Page 1 of 1

Immune profile differences between chronic GVHD and late acute GVHD: results of the ABLE/PBMTC 1202 studies.

Blood 2020 04;135(15):1287-1298

CancerCare Manitoba, University of Manitoba, Winnipeg, MB, Canada.

Human graft-versus-host disease (GVHD) biology beyond 3 months after hematopoietic stem cell transplantation (HSCT) is complex. The Applied Biomarker in Late Effects of Childhood Cancer study (ABLE/PBMTC1202, NCT02067832) evaluated the immune profiles in chronic GVHD (cGVHD) and late acute GVHD (L-aGVHD). Peripheral blood immune cell and plasma markers were analyzed at day 100 post-HSCT and correlated with GVHD diagnosed according to the National Institutes of Health consensus criteria (NIH-CC) for cGVHD. Of 302 children enrolled, 241 were evaluable as L-aGVHD, cGVHD, active L-aGVHD or cGVHD, and no cGVHD/L-aGVHD. Significant marker differences, adjusted for major clinical factors, were defined as meeting all 3 criteria: receiver-operating characteristic area under the curve ≥0.60, P ≤ .05, and effect ratio ≥1.3 or ≤0.75. Patients with only distinctive features but determined as cGVHD by the adjudication committee (non-NIH-CC) had immune profiles similar to NIH-CC. Both cGVHD and L-aGVHD had decreased transitional B cells and increased cytolytic natural killer (NK) cells. cGVHD had additional abnormalities, with increased activated T cells, naive helper T (Th) and cytotoxic T cells, loss of CD56bright regulatory NK cells, and increased ST2 and soluble CD13. Active L-aGVHD before day 114 had additional abnormalities in naive Th, naive regulatory T (Treg) cell populations, and cytokines, and active cGVHD had an increase in PD-1- and a decrease in PD-1+ memory Treg cells. Unsupervised analysis appeared to show a progression of immune abnormalities from no cGVHD/L-aGVHD to L-aGVHD, with the most complex pattern in cGVHD. Comprehensive immune profiling will allow us to better understand how to minimize L-aGVHD and cGVHD. Further confirmation in adult and pediatric cohorts is needed.
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April 2020

Identifying mechanisms for therapeutic intervention in chordoma: c-Met oncoprotein.

Spine (Phila Pa 1976) 2008 Dec;33(25):2774-80

From the Centre for Bioengineering Research and Education, University of Calgary, Calgary, Alberta, Canada.

Study Design: A human sacral chordoma cell line, CCL3, was established and in vitro characterization of c-Met oncoprotein in chordoma cells was performed.

Objective: Determination of whether c-Met plays an important role in chordoma's malignancy.

Summary Of Background Data: Chordomas are malignant life-threatening tumors that arise from the remnants of the notochord. c-Met is an oncoprotein that is expressed by a variety of solid tumors, including chordomas, and HGF is its high affinity ligand. In the present study, we investigated c-Met and HGF expression, localization, and function in human chordoma cells.

Methods: SDS-PAGE, Western blotting, immunofluorescence techniques, and cell migration functional assays were used to asses c-Met and HGF expression, localization, and functional activity.

Results: Intracellular protein tyrosine phosphorylation was enhanced on HGF binding, and an increase in the amount of 50 kDa alpha-chain of c-Met was detected in HGF-stimulated cells. Immunostaining of c-Met and HGF revealed membrane/cytoplasmic localization in nonstimulated cells, and perinuclear colocalization in HGF-stimulated cells. Positive chemotactic and migration activity in response to HGF was also demonstrated.

Conclusion: Our data supports our hypothesis that the c-Met oncoprotein plays a leading role in the metastatic process in chordomas, and that a c-Met-HGF pair is involved in chordoma malignancy. Taking into consideration the very limited treatment options and an extremely poor prognosis for the chordoma patients, our results are a valuable and promising addition to the current situation in managing chordomas.
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December 2008

Chordoma and chondrosarcoma gene profile: implications for immunotherapy.

Cancer Immunol Immunother 2009 Mar 19;58(3):339-49. Epub 2008 Jul 19.

Department of Surgery, Orthopedic Service, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA.

Chordoma and chondrosarcoma are malignant bone tumors characterized by the abundant production of extracellular matrix. The resistance of these tumors to conventional therapeutic modalities has prompted us to delineate the gene expression profile of these two tumor types, with the expectation to identify potential molecular therapeutic targets. Furthermore the transcriptional profile of chordomas and chrondrosarcomas was compared to a wide variety of sarcomas as well as to that of normal tissues of similar lineage, to determine whether they express unique gene signatures among other tumors of mesenchymal origin, and to identify changes associated with malignant transformation. A HG-U133A Affymetrix Chip platform was used to determine the gene expression signature in 6 chordoma and 14 chondrosarcoma lesions. Validation of selected genes was performed by qPCR and immunohistochemistry (IHC) on an extended subset of tumors. By unsupervised clustering, chordoma and chondrosarcoma tumors grouped together in a genomic cluster distinct from that of other sarcoma types. They shared overexpression of many extracellular matrix genes including aggrecan, type II & X collagen, fibronectin, matrillin 3, high molecular weight-melanoma associated antigen (HMW-MAA), matrix metalloproteinase MMP-9, and MMP-19. In contrast, T Brachyury and CD24 were selectively expressed in chordomas, as were Keratin 8,13,15,18 and 19. Chondrosarcomas are distinguished by high expression of type IX and XI collagen. Because of its potential usefulness as a target for immunotherapy, the expression of HMW-MAA was analyzed by IHC and was detected in 62% of chordomas and 48% of chondrosarcomas, respectively. Furthermore, western blotting analysis showed that HMW-MAA synthesized by chordoma cell lines has a structure similar to that of the antigen synthesized by melanoma cells. In conclusion, chordomas and chondrosarcomas share a similar gene expression profile of up-regulated extracellular matrix genes. HMW-MAA represents a potential useful target to apply immunotherapy to these tumors.
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March 2009

The role of extracellular factors in human metastatic chordoma cell growth in vitro.

Spine (Phila Pa 1976) 2007 Dec;32(26):2957-64

Centre for Bioengineering Research and Education, University of Calgary, Calgary Centre for Innovative Technology, University of Calgary, Calgary, Alberta, Canada.

Study Design: Human metastatic chordoma cells were isolated, and initial in vitro characterization was performed. Biochemical and physiologic changes were observed in response to pH, oxygen, and glucose.

Objective: The extracellular microenvironment directly affects metastatic chordoma cell phenotype in vitro.

Summary Of Background Data: Chordomas are primary bone tumors that usually occur in the spine or skull. Chordomas arise from embryonic notochordal remnants along the axial skeleton, most commonly the sacrum, followed by the base of the skull and the mobile spine. Due to a high degree of resistance to radiation and chemotherapy, chordomas eventually cause death by direct growth or by metastasizing to other organs.

Methods: Extracellular pH, oxygen, and glucose levels in the culture medium were controlled, and cell response was assessed using MTT staining, SDS-PAGE, Western blotting, tandem mass spectrometry, TUNEL, immunofluorescence, and flow cytometry.

Results: In this study, we present a new chordoma cell line established from metastatic tissue and novel data characterizing some aspects of chordoma cell phenotype in different conditions in vitro. Chordoma biologic markers were expressed in the new cell line. Alkaline pH dramatically increased intracellular protein tyrosine phosphorylation, metabolic activity, and albumin accumulation in the cells, while acidic pH caused apoptosis.

Conclusion: The level of proliferation, apoptosis, and tyrosine phosphorylation, as well as the overall protein expression profile, strongly depended on extracellular media pH and oxygen/glucose levels. Chordoma's preferred extracellular microenvironment in vitro was rather alkaline, with an optimum at pH 8.5, and apoptotic changes were induced at acidic pH. We found that bovine serum albumin was accumulated by chordoma cells from the incubation media, and this accumulation depended on extracellular pH, with the highest accumulation at alkaline pH.
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December 2007

Asp(344) and Thr(345) are critical for cation exchange mediated by NhaD, Na(+)/H(+) antiporter of Vibrio cholerae.

Biochim Biophys Acta 2002 Aug;1564(1):99-106

Faculty of Science, Department of Microbiology, University of Manitoba, R3T 2N2 Winnipeg, Manitoba, Canada.

The Vc-NhaD is an Na(+)/H(+) antiporter from Vibrio cholerae belonging to a new family of bacterial Na(+)/H(+) antiporters, the NhaD family. In the present work we mutagenized five conserved Asp and Glu residues and one conserved Thr residue to Ala in order to identify amino acids that are critical for the antiport activity. All mutations fall into two distinct groups: (i) four variants, Glu(100)Ala, Glu(251)Ala, Glu(342)Ala, and Asp(393)Ala, did not abolish antiport activity but shifted the pH optimum to more alkaline pH, and (ii) variants Asp(344)Ala, Asp(344)Asn, and Thr(345)Ala caused a complete loss of both Na(+)/H(+) and Li(+)/H(+) antiport activity whereas the Asp(344)Glu variant exhibited reduced Na(+)/H(+) and Li(+)/H(+) antiport activity. This is the first mutational analysis of the antiporter of NhaD type and the first demonstration of Thr residue being indispensable for Na(+)/H(+) antiport. We discuss the possible role of Asp(344) and Thr(345) in the functioning of Vc-NhaD.
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August 2002

Cloning, functional expression in Escherichia coli and primary characterization of a new Na+/H+ antiporter, NhaD, of Vibrio cholerae.

Mol Cell Biochem 2002 Jan;229(1-2):119-24

Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Canada.

Vibrio cholerae is the infectious agent of the deadly diarrheal disease, cholera. Na+ ion homeostasis is believed to play a key role in both physiology and pathogenicity of this bacterium. However, molecular mechanisms of sodium exchange in V. cholerae are still poorly understood. In the present work a gene encoding an unusual Na+/H+ antiporter, nhaD, was identified in the V. cholerae genome. nhaD was cloned from Vibrio cholerae and expressed in Escherichia coli. The antiporter functioned in an E. coli nhaAnhaB mutant strain to confer resistance to LiCl and NaCl. When assayed in inside-out subbacterial vesicles, V. cholerae NhaD demonstrated high affinity for Na+ ions (1.1 mM Na+ was required for the half-maximal response at the pH-optimum). The most striking feature of Vc-NhaD is a unique pH-profile of its activity with a sharp maximum at pH 8.0, different from that of any bacterial sodium-proton antiporter described so far. The difference is rationalized as being the result of a His to Arg substitution in a putative pH sensing residue.
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January 2002