Biomedical subjects

Keith M Skubitz

Publications and source records attributed to Keith M Skubitz.

At least 19 recordsLinked to original sources

PubMed2006

Differential gene expression identifies subgroups of renal cell carcinoma.

Clear cell carcinoma of the kidney, the most common subtype of renal cell cancer, displays different biological behavior in different patients. This heterogeneity cannot be recognized by light microscopy. In this study, gene expression in 16 clear cell renal cell carcinoma samples and 17 non-malignant tissue types comprising 539 samples was determined using oligonucleotide microarrays representing approximately 40,000 known genes and ESTs. Differences in gene expression were quantified as the fold change in gene expression between the various sets of samples. A set of genes was identified that was overexpressed in the renal cell carcinoma samples compared with the normal kidney samples. Principle component analysis of the set of renal cell carcinomas using this set of genes overexpressed in renal cell cancer revealed the existence of 2 major subgroups among the renal carcinomas. A series of principle component analyses of the set of renal cell carcinomas using different gene sets composed of genes involved in different metabolic pathways also revealed the same 2 major subgroups of the renal cell cancers. Eisen clustering using the same genes also revealed the same 2 major renal cell cancer subsets. Review of the pathology suggested that these 2 subgroups differed in pathologic grade. Genes differentially expressed between the 2 renal cell cancer subsets were identified. Examination of gene expression in each renal cell cancer subset and the pool of renal cell carcinoma samples compared with that in 17 different normal tissues revealed genes specifically overexpressed in renal cell cancer compared with these normal tissues. The authors conclude that gene expression patterns may be useful in helping to further classify subtypes of renal cell carcinoma that may have clinical significance. In addition, the genes identified as overexpressed in each set of clear cell renal cell carcinomas compared with normal tissues may represent useful targets for therapy.

Adult↗

PubMed2006

Differential gene expression identifies subgroups of ovarian carcinoma.

Papillary serous ovarian carcinoma, the most common type of ovarian cancer, displays different biological behavior in different patients. This heterogeneity cannot be recognized by light microscopy. In this study, gene expression in 29 papillary serous ovarian carcinoma samples (21 invasive tumors and 8 borderline tumors), and 17 nonmalignant tissue types comprising 512 samples, was determined using Affymetrix U_133 oligonucleotide microarrays (Affymetrix, Inc., Santa Clara, Calif) representing approximately 40,000 known genes and expression sequence tags (ESTs). Differences in gene expression were quantified as the fold change in gene expression between the various sets of samples. A set of genes was identified that was over-expressed in the invasive ovarian carcinoma samples compared with the normal ovary samples. Principle component analysis of the set of invasive ovarian carcinomas using this set of genes revealed the existence of 2 major subgroups among the invasive ovarian carcinomas. A series of principle component analyses of the ovarian carcinomas using different gene sets composed of genes involved in different metabolic pathways also revealed the same 2 major subgroups of the invasive ovarian carcinomas. Review of the pathology by a single pathologist in a blinded manner suggested that these 2 subgroups differed in pathologic grade. Genes differentially expressed between the 2 ovarian carcinoma subsets were identified. Examination of gene expression in each ovarian carcinoma subset compared with that in 17 different normal tissue types (512 samples) revealed genes specifically over-expressed in ovarian carcinoma compared with these normal tissues. It is concluded that gene expression patterns may be useful in helping to further classify subtypes of papillary serous ovarian carcinoma that may have clinical significance. In addition, the genes identified as over-expressed in each set of serous ovarian carcinoma compared with normal tissues may represent potential biomarkers and/or targets for therapy.

Adipose Tissue↗

PubMed2005

Protein kinase activity is associated with CD63 in melanoma cells.

BACKGROUND: The tetraspan protein CD63, originally described as a stage-specific melanoma antigen but also present in a number of normal cells, regulates melanoma cell growth in nude mice, motility in serum containing media, and adhesion to several extracellular matrix proteins. CD63 has been reported to associate with beta1 and beta2 integrins, but the mechanism of signal transduction by CD63 is not clear. This study examined whether CD63 is associated with protein kinase and can transmit signals in melanoma cells. METHODS: Immunoprecipitation and radiolabeling were used to test for association of protein kinase activity with CD63. Adhesion of cells to monoclonal antibodies immobilized to microtiter plates was used to examine the ability of CD63 to transmit signals. RESULTS: CD63 was capable of transmitting a signal in melanoma cells that required extracellular calcium. In the absence of extracellular calcium at the time of binding to the CD63 mAb, the cell was no longer responsive to stimulation by CD63. Immunoprecipitation studies demonstrated protein kinase activity associated with CD63, and phosphoamino acid analysis revealed that most of this protein kinase activity was due to serine kinase activity. CONCLUSION: The current study suggests that serine protein kinase activity associated with CD63 may play a role in signaling by CD63 in melanoma cells.

Journal Article↗

PubMed2005

The subcellular distribution of myeloid-related protein 8 (MRP8) and MRP14 in human neutrophils.

BACKGROUND: Myeloid-related protein 8 (MRP8) and MRP14 are S100 family calcium binding proteins that form a heterodimer known as calprotectin or MRP8/14 that is present in the cytosol of neutrophils and monocytes. MRP8/14 becomes associated with endothelium at sites of monocyte and neutrophil adhesion and transmigration and induces a thrombogenic and inflammatory response by increasing the endothelial transcription of proinflammatory chemokines and adhesion molecules. The distribution of MRP8/MRP14 among neutrophil granules and plasma membranes is unclear and was investigated to better understand the role of this molecule in acute inflammation. STUDY DESIGN: Three monoclonal antibodies specific for MRP8 and MRP14 were characterized and used in immunoblotting assays of neutrophil whole cell extracts, and isolated plasma membranes, primary granules, secondary granules and cytosol. RESULTS: MRP8 and MRP14 were detected in neutrophil cytosol, plasma membrane, primary granule and secondary granule fractions. MRP8/14 demonstrated a calcium-dependent adherence to plasma membranes and primary granules and could be removed by washing with EGTA in a high ionic strength buffer. In contrast, MRP8/14 was found within the contents of the secondary granules. Activated neutrophils released secondary granules and MRP8/14. CONCLUSION: MRP8/14 is located in neutrophil cytosol and secondary granule fractions and is loosely associated with plasma membranes. MRP8/14 released with secondary granules by activated neutrophils likely binds to endothelium and plays an important role in acute inflammation.

Journal Article↗

PubMed2005

Paclitaxel and pegylated-liposomal doxorubicin are both active in angiosarcoma.

BACKGROUND: Paclitaxel has unique activity in angiosarcomas of the face and scalp, but its activity in angiosarcomas originating at other sites is less well defined. Paclitaxel and pegylated-liposomal doxorubicin (PLD) are highly effective in Kaposi sarcoma (KS). Because of the efficacy of PLD in soft tissue sarcoma in general, and in KS in particular, coupled with potential similarities in KS and angiosarcoma, and the apparent activity of paclitaxel in angiosarcomas, the authors treated patients with angiosarcoma with either paclitaxel or PLD as initial chemotherapy. METHODS: To better define the efficacy of these agents in angiosarcoma, the authors reviewed their experience with paclitaxel and PLD in patients with angiosarcoma treated between 1994 and 2004. RESULTS: They identified seven patients with angiosarcoma treated with paclitaxel, and six treated with PLD. Only one patient in the series had an angiosarcoma of the scalp. Two patients receiving paclitaxel had received previous therapy with PLD, and four of six patients treated with PLD had previously received paclitaxel. Of the eight patients treated with paclitaxel, five had major responses (three had partial responses [PR] and two had complete disease remission [CR]) and three had progressive disease (PD). Of the 6 patients who received PLD, 3 had a PR for 6, 19, and >20 months, respectively, 2 had stable disease for 7 and 11 months, respectively, and 1 had PD. CONCLUSIONS: The current study demonstrated the activity of PLD (five of six patients experienced clinical benefit) and extended the data on paclitaxel in angiosarcoma, both of the face and scalp, as well as angiosarcoma originating at other sites.

Aged↗

PubMed2005

Differential gene expression in liposarcoma, lipoma, and adipose tissue.

Malignant transformation is thought to be associated with changes in the expression of a number of genes, and this alteration in gene expression is felt to be critical to the development of the malignant phenotype. Sarcomas represent a diverse group of tumors derived from cells of mesenchymal origin. Marked heterogeneity exists in the biological behavior of sarcomas, even within histologic subtypes of sarcomas. In an effort to better understand the biology of liposarcomas, gene expression in normal adipose tissue, lipomas, and liposarcomas was examined using the Affymetrix microarray technology. Differences in gene expression were quantified as the fold change in gene expression among the sample sets. Differences in gene expression among normal adipose tissue, lipomas, and liposarcomas were observed. In addition, genes expressed uniquely in liposarcoma among these and 18 other tissue sample sets were identified. Gene sets were devised that allowed the separation of liposarcomas from other samples, and most normal adipose tissue from most lipomas using the Eisen clustering software "Cluster." We conclude that differences in gene expression can be identified among different tumors derived from the adipocyte series. Such differences in gene expression may help differentiate among subtypes of sarcomas, and may also yield clues to the pathophysiology of this heterogeneous group of tumors.

Adipose Tissue↗

PubMed2004

Role of gene expression arrays in sarcomas.

Microarray technology allows the rapid analysis of expression of thousands of genes in a sample. Gene expression profiles are likely characteristic of subtypes of sarcomas and may be useful in diagnosis and classification of this heterogeneous group of tumors. Gene expression may also be useful prognostically with respect to the natural history and response to therapy of these tumors.

Biomarkers, Tumor↗

PubMed2004

Gene expression in aggressive fibromatosis.

Aggressive fibromatosis represents a group of tumors with heterogeneous patterns of biologic behavior. In this study, gene expression in 12 samples of aggressive fibromatosis, as well as that in samples of normal skeletal muscle and a variety of normal tissues, was determined at Gene Logic Inc (Gaithersburg, MD), with the use of Affymetrix GeneChip U_133 arrays containing approximately 33,000 genes. Gene-expression analysis was performed with the Gene Logic Gene Express software system. Differences in gene expression were quantified as the fold change in gene expression between the sets of fibromatosis tissue and normal skeletal muscle. A set of genes was then identified that was significantly overexpressed in aggressive fibromatosis compared with expression in normal muscle. This set of genes was then further examined for expression in a variety of normal tissues. We identified genes that were selectively overexpressed in aggressive fibromatosis compared with expression in 448 samples comprising 16 different nonneoplastic tissues. In particular, ADAM12, WISP-1, SOX-11, and fibroblast activation protein-alpha were uniquely overexpressed in aggressive fibromatosis compared with expression in normal tissues. In addition, the technique of Eisen clustering identified 2 distinct subgroups of aggressive fibromatosis with regard to gene expression. We conclude that gene-expression patterns may be useful in the further classification of subtypes of aggressive fibromatosis and that such classification could have clinical significance.

Adolescent↗

PubMed2004

Characterization of sarcomas by means of gene expression.

Sarcomas represent a heterogeneous group of diseases of a variety of recognized histologic types. Among these subtypes is malignant fibrous histiocytoma (MFH), a diagnosis no longer recognized as a specific diagnosis at some institutions. In this study, gene expression in 38 histologically well-defined sarcoma samples, 17 MFH samples, 12 samples of sarcomas classified simply as high-grade sarcoma (NOS, standing for "not otherwise specified"), and 26 other mesenchymal tumors was determined at Gene Logic Inc (Gaithersburg, MD), with the use of Affymetrix GeneChip U_133 arrays containing approximately 40,000 known genes and expressed sequence tags (ESTs). Gene-expression analysis was performed with the use of the Gene Logic Gene Express(R) Software System. Differences in gene expression were quantified as the fold change in gene expression between the various sets of well-defined sarcomas. A set of genes was then identified that could be used to distinguish the well-defined sets of 11 liposarcomas, 9 leiomyosarcomas, 4 synovial sarcomas, 8 schwannomas, and 12 cases of aggressive fibromatosis through the use of Eisen clustering. Eisen clustering was then repeated with the same set of gene fragments with the sample set of 38 histologically well-defined sarcomas, the 17 sarcomas classified as MFH, 12 sarcomas classified as high-grade sarcoma (NOS), and 26 other mesenchymal tumors. Under these conditions, each of the samples of well-defined sarcoma formed distinct clusters that contained some of the MFH and NOS samples. In addition, distinct clusters were observed that contained only MFH and NOS samples. We conclude that gene-expression patterns may be useful in helping further classify subtypes of sarcomas.

Adult↗

PubMed2004

Gene expression in giant-cell tumors.

Malignant transformation is thought to be associated with changes in the expression of a number of genes, and this alteration in gene expression is considered critical to the development of the malignant phenotype. In this study, gene expression in 8 samples of giant-cell tumor (GCT) of bone, as well as in bone at the site of osteoarthritis and in a variety of normal tissues, was determined at Gene Logic Inc (Gaithersburg, Md) with the use of Affymetrix GeneChip U_133 arrays containing approximately 40,000 genes/expressed sequence tags (ESTs). Gene-expression analysis was performed with the use of the Gene Logic GeneExpress Software System. Differences in gene expression between GCTs and bone were observed. In addition, genes expressed uniquely in GCTs among these and 519 samples from 20 other tissue types were identified. Some of the genes that were found to be overexpressed in GCTs, such as tartrate-resistant acid phosphatase and the lysosomal H + -transporting ATPase, are also expressed by osteoclasts. Osteoprotegrin ligand (OPGL) was also selectively overexpressed in GCTs. The genes found to be overexpressed in GCTs appear to reflect the genetic profile of osteoclast-lineage cells and also the genetic profile of an osteoclastogenic environment. The genes identified in this study may play a role in the pathogenesis of GCTs, confirm the likely importance of OPGL in GCT pathogenesis, and may indicate other possible targets to which antitumor therapy could be directed.

Adolescent↗

PubMed2004

Ovarian carcinoma ascites spheroids adhere to extracellular matrix components and mesothelial cell monolayers.

OBJECTIVES: Ovarian carcinoma cells form multicellular aggregates, or spheroids, in the peritoneal cavity of patients with advanced disease. The current paradigm that ascites spheroids are non-adhesive leaves their contribution to ovarian carcinoma dissemination undefined. Here, spheroids obtained from ovarian carcinoma patients' ascites were characterized for their ability to adhere to molecules encountered in the peritoneal cavity, with the goal of establishing their potential to contribute to ovarian cancer spread. METHODS: Spheroids were recovered from the ascites fluid of 11 patients with stage III or stage IV ovarian carcinoma. Adhesion assays to extracellular matrix (ECM) proteins and human mesothelial cell monolayers were performed for each of the ascites spheroid samples. Subsequently, inhibition assays were performed to identify the cell receptors involved. RESULTS: Most ascites samples adhered moderately to fibronectin and type I collagen, with reduced adhesion to type IV collagen and laminin. Monoclonal antibodies against the beta1 integrin subunit partially inhibited this adhesion. Ascites spheroids also adhered to hyaluronan. Additionally, spheroids adhered to live, but not fixed, human mesothelial cell monolayers, and this adhesion was partially mediated by beta1 integrins. CONCLUSIONS: The cellular content of the ascites fluid has often been considered non-adhesive, but our findings are the first to suggest that patient-derived ascites spheroids can adhere to mesothelial extracellular matrix via beta1 integrins, indicating that spheroids should not be ignored in the dissemination of ovarian cancer.

Ascites↗

PubMed2004

Differential gene expression in ovarian carcinoma: identification of potential biomarkers.

Ovarian cancer remains the fifth leading cause of cancer death for women in the United States. In this study, the gene expression of 20 ovarian carcinomas, 17 ovarian carcinomas metastatic to the omentum, and 50 normal ovaries was determined by Gene Logic Inc. using Affymetrix GeneChip HU_95 arrays containing approximately 12,000 known genes. Differences in gene expression were quantified as fold changes in gene expression in ovarian carcinomas compared to normal ovaries and ovarian carcinoma metastases. Genes up-regulated in ovarian carcinoma tissue samples compared to more than 300 other normal and diseased tissue samples were identified. Seven genes were selected for further screening by immunohistochemistry to determine the presence and localization of the proteins. These seven genes were: the beta8 integrin subunit, bone morphogenetic protein-7, claudin-4, collagen type IX alpha2, cellular retinoic acid binding protein-1, forkhead box J1, and S100 calcium-binding protein A1. Statistical analyses showed that the beta8 integrin subunit, claudin-4, and S100A1 provided the best distinction between ovarian carcinoma and normal ovary tissues, and may serve as the best candidate tumor markers among the seven genes studied. These results suggest that further exploration into other up-regulated genes may identify novel diagnostic, therapeutic, and/or prognostic biomarkers in ovarian carcinoma.

Adenocarcinoma, Papillary↗

PubMed2004

Efficacy and safety of liposomal anthracyclines in phase I/II clinical trials.

Preclinical studies have established the pharmacologic advantages of liposomal anthracyclines, including pharmacokinetic profiles after bolus dosing that resemble continuous infusion of conventional anthracyclines, increased drug concentrations in tumor cells compared with the surrounding tissues, and reduced toxicity relative to conventional anthracycline treatment. Based on these studies, many phase I and phase II clinical trials were conducted to assess the safety and potential activity of liposomal anthracyclines in the management of both solid and hematologic tumors. These studies provided valuable insight into the safety of pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]), nonpegylated liposomal doxorubicin (Myocet [NPLD]), and liposomal daunorubicin (DaunoXome [DNX]) over a range of doses, either as single-agent therapy or in combination with other cytotoxic agents. Other liposomal anthracyclines in development may be well tolerated but their activity remains to be elucidated by clinical trials. The available data also suggest that liposomal anthracyclines have activity not only against tumor types with known sensitivity to conventional anthracyclines, but also potentially for tumors that are typically anthracycline-resistant. Despite the availability of clinical data from a wide variety of tumor types and patient populations, further studies of liposomal anthracycline therapy are needed to fully establish their safety, efficacy, and dosing in the treatment of these patients.

Antibiotics, Antineoplastic↗

PubMed2003

Differential gene expression in leiomyosarcoma.

BACKGROUND: Leiomyosarcomas (LMS) are a common subtype of soft tissue sarcoma. The molecular causes of the disease remain unclear. METHODS: In the current study, gene expression in LMS, leiomyomas, and normal myometrium was examined. RNA was prepared and gene expression was determined using microarray analysis arrays containing approximately 12,000 known genes and 48,000 expressed sequence tags (ESTs). RESULTS: A number of genes were found to be differentially expressed in these sample sets, and six genes including cyclin-dependent kinase inhibitor 2A, diaphanous (Drosophila homolog) 3, doublecortin, calpain 6, interleukin-17B, and proteolipid 1 were found to be overexpressed in LMS compared with normal myometrium and 18 other tissues. Sets of genes were identified whose expression could be used to cluster samples with either LMS, leiomyomas, or normal myometrium. CONCLUSIONS: The authors concluded that differences in gene expression can be detected between LMS and leiomyomas, normal myometrium, and other tissues, and that these changes in gene expression may yield clues with regard to the pathophysiology of leiomyosarcoma.

Adult↗

PubMed2003

CD98-dependent homotypic aggregation is associated with translocation of protein kinase Cdelta and activation of mitogen-activated protein kinases.

CD98 is a protein found on the surface of many activated cell types, and is implicated in the regulation of cellular differentiation, adhesion, growth, and apoptosis. Despite many studies addressing CD98 function, there is little information on the intracellular signalling pathways that mediate its activity. In this study, we examine protein kinase pathways that are activated following ligation by the CD98 antibody AHN-18, an antibody that induces U937 homotypic aggregation and inhibits antigen presenting activity and T-cell activation. Ligation by CD98 antibody AHN-18 induces tyrosine kinase activity, but inhibition of this activity does not affect U937 aggregation. Ligation also induces membrane translocation of the serine/threonine kinase novel PKCdelta, but not other members of the PKC family. Translocation is blocked by rottlerin, and this inhibitor also blocks aggregation. PKCdelta activation in turn mediates activation of ERK1/2 and p38, as well as tyrosine phosphorylation of multiple proteins, and MAPK activation is essential for cellular aggregation. One of the targets of CD98-induced tyrosine phosphorylation is itself PKCdelta, suggesting that this phosphorylation may act as a negative feedback to limit the overall activation of the CD98 pathway.

Adrenergic beta-Antagonists↗

PubMed2003

Differential gene expression in uterine leiomyoma.

Uterine leiomyomas are the most common tumor of the genitourinary system in women and are a major cause of morbidity. The molecular causes of the disease remain unclear. In this study, we examined gene expression in leiomyomas and normal myometrium. RNA was prepared and gene expression determined with the use of Affymetrix GeneChip U_95 arrays containing approximately 12,000 known genes and 48,000 expression sequence tags. Several genes were found to be differentially expressed in these two sample sets, and these genes were analyzed for their expression in a variety of other normal and diseased tissues. Four genes--doublecortin, calpain 6, interleukin-17B, and proteolipid protein 1--were found to be overexpressed in leiomyomas compared with normal myometrium and eighteen other tissues. Sets of genes were identified whose expression could be used to cluster samples with leiomyomas or normal myometrium with the use of Eisen Cluster software. We conclude that differences in gene expression can be detected between leiomyomas and normal myometrium and that these changes in gene expression may yield clues to the pathophysiology of this common tumor.

Adult↗

PubMed2003

Cell membrane glycosylation mediates the adhesion, migration, and invasion of ovarian carcinoma cells.

We have previously shown that ovarian carcinoma cell adhesion to mesothelial cell monolayers and migration toward fibronectin, type IV collagen, and laminin is partially mediated by CD44, a proteoglycan known to affect the functional abilities of tumor cells. The purpose of this study was to determine the role of cell membrane glycosylation in the metastatic abilities of ovarian carcinoma cells. NIH:OVCAR5 cells were treated with glycosidases to remove carbohydrate moieties from molecules on the cells' surface. The ability of the treated cells to adhere to extracellular matrix components or mesothelial cell monolayers, migrate toward extracellular matrix proteins, and invade through Matrigel was assessed. We observed that the loss of different carbohydrate moieties resulted in altered ovarian carcinoma cell adhesion, migration, and/or invasion toward extracellular matrix components or mesothelial cell monolayers. Gene array analysis of NIH:OVCAR5 cells revealed the expression of several proteoglycans, including syndecan 4, decorin, and perlecan. In tissue samples obtained from patients, altered proteoglycan gene expression was observed in primary ovarian carcinoma tumors and secondary metastases, compared to normal ovaries. Taken together, these results suggest that ovarian carcinoma cell proteoglycans affect the cells' ability to adhere, migrate, and invade toward extracellular matrix components and mesothelial cell monolayers. Thus, the carbohydrate modifications of several proteoglycans may mediate the formation and spread of secondary tumor growth in ovarian carcinoma.

Cell Adhesion↗

PubMed2003

Establishment of an in vitro assay to measure the invasion of ovarian carcinoma cells through mesothelial cell monolayers.

Ovarian carcinoma is the leading cause of gynecological cancer deaths in the United States. Secondary tumor growths form by tumor cell invasion through the mesothelial lining of the peritoneal cavity and peritoneal organs. To study this interaction, we developed a dye-based in vitro model system in which mesothelial cells were grown as confluent monolayers, permeabilized, and then co-cultured with ovarian carcinoma cells for up to seven days. The mesothelial cells were then stained with trypan blue dye, which enabled the visualization of ovarian carcinoma cell invasion through the monolayers of mesothelial cells. Ovarian carcinoma cell invasion was inhibited for up to 7 days by the addition of GRGDSP peptides, a blocking monoclonal antibody against the beta1 integrin subunit, or blocking monoclonal antibodies against matrix metalloproteinases 2 and 9. Cell invasion was also inhibited by hyaluronan and GM6001, a chemical inhibitor of matrix metalloproteinases. Differential gene expression of matrix metalloproteinases, tissue inhibitors of matrix metalloproteinases, and disintegrins were observed in primary ovarian carcinoma tumors and secondary metastases, compared to normal ovaries. Taken together, these results suggest that complex interactions between integrins, disintegrins, matrix metalloproteinases, and tissue inhibitors of matrix metalloproteinases may mediate ovarian carcinoma cell invasion, and that the dye-based assay described herein is a suitable model system for its study.

Adenocarcinoma↗