Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an effort to expand human hematopoietic progenitors and stem cells in vitro, we cultured human CD34(+)c-kitlow bone marrow cells in suspension in the presence of KIT ligand, FLK2/FLT3 ligand, interleukin-6 (IL-6), and erythropoietin with or without IL-3 and tested their engrafting capabilities by injecting them into sheep fetuses. As markers for engraftment, we analyzed CD45(+) cells and karyotypes of the colonies grown in methylcellulose culture. In three separate experiments, day-60 engraftment in the bone marrow was seen with both fresh cells and cells cultured in the presence or absence of IL-3. When fetuses were allowed to be born and analyzed for CD45(+) cells, no long-term engraftment was seen with cultured cells. We then pooled the CD45(+) cells of the fetal samples and transplanted them into secondary recipient fetuses. Day-60 engraftment in the secondary recipients was again noted when transplantation in the primary recipients was initiated with fresh cells. There were 3 cases in which cultured cells showed signs of engraftment in the secondary recipients, but the remaining 24 cases showed no signs of engraftment. These data documented that suspension culture for 2 weeks of enriched adult human bone marrow cells can maintain short-term (2 months) engrafting cells, but may not maintain longer term engrafting cells. This sheep/human xenograft model may serve as an excellent method for the evaluation of the engraftment potential of in vitro-expanded cells.
 ...
PMID:Engraftment of cultured human hematopoietic cells in sheep. 957 5

A large number of continuous human leukemia cell lines have been established over the last three decades. Clearly, leukemia cell lines have become important research tools. Here, we have summarized the immunological, molecular and standard cytogenetic features of a panel of well characterized B cell precursor (BCP)-leukemia cell lines which were derived from patients with acute lymphoblastic/undifferentiated leukemia (ALL/AUL) or chronic myeloid leukemia (CML) in blast crisis. Following the recently proposed immunological EGIL classification, we assigned our panel of 27 BCP-cell lines to one of the following categories: B-I pro-B cell line; B-II common-B cell line; and B-III pre-B cell line. All cell lines express general B-lineage associated surface markers (HLA-DR, CD22, CD79a) being negative for surface immunoglobulin (Ig); the differences between the subgroups reside in expression of CD10 and cytoplasmic Ig. Several BCP-cell lines show the myelomonocytic cell-associated markers CD13 and/or CD33. These immunologically 'biphenotypic' BCP-cell lines are generally TdT+ CD10+ CD13+ CD19+ CD22+ CD34+ and carry the Philadelphia (Ph) translocation. The BCP-cell lines display surface receptors for interferon-gamma (CD119), interleukin-7 (CD127) and FLT-3 ligand (CD135). All BCP-cell lines examined have complex numerical and structural chromosomal alterations including translocations commonly seen in BCP-ALL such as t(4;11), t(9;22), t(11;19), t(12;21), and t(17;19) involving the fusion genes MLL-AF4, BCR-ABL, ENL-MLL, TEL/ETV6-AML1 and E2A-HLF, respectively. Besides the expected rearrangement of the Ig heavy chain receptor gene, several cell lines also have rearrangements of the T cell receptor genes beta, gamma or delta. While some BCP-cell lines express (aberrantly) myeloperoxidase at the mRNA level, most lines are negative in the immunological or cytochemical staining. Several large series documented the difficulty in establishing such BCP cell lines with success rates in the range of 10-20% (on average 15%). Still, since the establishment of the first bonafide BCP-cell line in 1974 (cell line REH), some 150 cell lines have been established of which, however, only a small percentage have been sufficiently well characterized and described. A higher success rate for immortalizing any given leukemia cell might depend on a closer emulation of the physiological in vivo microenvironment. The possibility to grow in vitro leukemia cells at will would represent ideal experimental systems permitting basic research and patient-specific investigations. In summary, the use of well-characterized BCP-cell lines provide unprecedented opportunities for studying a multitude of biological aspects related to normal and neoplastic B-lymphocytes.
 ...
PMID:Establishment and characterization of human B cell precursor-leukemia cell lines. 968 Jan 6

CD164 is a novel 80- to 90-kD mucin-like molecule expressed by human CD34(+) hematopoietic progenitor cells. Our previous results suggest that this receptor may play a key role in hematopoiesis by facilitating the adhesion of CD34(+) cells to bone marrow stroma and by negatively regulating CD34(+) hematopoietic progenitor cell growth. These functional effects are mediated by at least two spatially distinct epitopes, defined by the monoclonal antibodies (MoAbs), 103B2/9E10 and 105A5. In this report, we show that these MoAbs, together with two other CD164 MoAbs, N6B6 and 67D2, show distinct patterns of reactivity when analyzed on hematopoietic cells from normal human bone marrow, umbilical cord blood, and peripheral blood. Flow cytometric analyses revealed that, on average, 63% to 82% of human bone marrow and 55% to 93% of cord blood CD34(+) cells are CD164(+), with expression of the 105A5 epitope being more variable than that of the other identified epitopes. Extensive multiparameter flow cytometric analyses were performed on cells expressing the 103B2/9E10 functional epitope. These analyses showed that the majority (>90%) of CD34(+) human bone marrow and cord blood cells that were CD38(lo/-) or that coexpressed AC133, CD90(Thy-1), CD117(c-kit), or CD135(FLT-3) were CD164(103B2/9E10)+. This CD164 epitope was generally detected on a significant proportion of CD34(+)CD71(lo/-) or CD34(+)CD33(lo/-) cells. In accord with our previous in vitro progenitor assay data, these phenotypes suggest that the CD164(103B2/9E10) epitope is expressed by a very primitive hematopoietic progenitor cell subset. It is of particular interest to note that the CD34(+)CD164(103B2/9E10)lo/- cells in bone marrow are mainly CD19(+) B-cell precursors, with the CD164(103B2/9E10) epitope subsequently appearing on CD34(lo/-)CD19(+) and CD34(lo/-)CD20(+) B cells in bone marrow, but being virtually absent from B cells in the peripheral blood. Further analyses of the CD34(lo/-)CD164(103B2/9E10)+ subsets indicated that one of the most prominent populations consists of maturing erythroid cells. The expression of the CD164(103B2/9E10) epitope precedes the appearance of the glycophorin C, glycophorin A, and band III erythroid lineage markers but is lost on terminal differentiation of the erythroid cells. Expression of this CD164(103B2/9E10) epitope is also found on developing myelomonocytic cells in bone marrow, being downregulated on mature neutrophils but maintained on monocytes in the peripheral blood. We have extended these studies further by identifying Pl artificial chromosome (PAC) clones containing the CD164 gene and have used these to localize the CD164 gene specifically to human chromosome 6q21.
 ...
PMID:CD164, a novel sialomucin on CD34(+) and erythroid subsets, is located on human chromosome 6q21. 968 Mar 53

The fate of hematopoietic progenitor cells (HPCs) in the bone marrow (BM) microenvironment is determined by two different interactions: 1) they adhere (via integrins) to both extracellular matrix molecules and BM stromal cells; and 2) stromal cells produce cytokines that influence their survival, proliferation, differentiation, and mobilization. The ligands for the protein tyrosine kinase receptors c-KIT and FLT3/FLK2, stem cell factor (SCF), and FL are produced by BM stromal cells and are known to affect several facets of hematopoiesis. We studied another protein tyrosine kinase receptor, c-MET, and its ligand hepatocyte growth factor (HGF), also known as scatter factor (SF), which play a similar role in hematopoiesis. c-MET mRNA is expressed in immature human BM HPCs (CD34+CD33- or CD34+CD38-), but not in more mature HPCs (CD34+CD33+ or CD34+CD38+). The ligand HGF/SF is predominantly produced by BM stromal cells at both the mRNA and protein levels. We confirmed functionally that HGF/SF alone has no effect on proliferation of HPCs, but that when combined with granulocyte/macrophage colony-stimulating factor (GM-CSF) or interleukin-3 it acts as a synergistic proliferative factor, although not as potently as kit-ligand or FLT-3/FLK-2 ligand. Furthermore, HGF/SF promotes adhesion of HPCs to immobilized fibronectin. HGF/SF-induced adhesion to fibronectin is probably caused by activation of the integrins alpha4beta1 and alpha5beta1, insofar as we were able to block this interaction by using monoclonal blocking antibodies directed against these integrin subunits. Addition of the tyrosine-phosphorylation inhibitor genistein inhibited HGF/SF-induced adhesion, supporting the idea that HGF/SF-induced effects are the result of signaling via the receptor c-MET after ligand binding. The enhanced adhesion of HGF/SF to fibronectin proved to be beneficial for the maintenance of the colony-forming potential of HPCs. HGF/SF alone and especially in combination with fibronectin prolongs survival of GM colony-forming cells in liquid culture. Our data indicate that HGF/SF is a polyfunctional cytokine in the BM microenvironment. It is produced by human BM stromal cells and directly or indirectly promotes proliferation, adhesion, and survival of human HPCs.
 ...
PMID:Hepatocyte growth factor/scatter factor (HGF/SF) is produced by human bone marrow stromal cells and promotes proliferation, adhesion and survival of human hematopoietic progenitor cells (CD34+). 969 10

We analyzed tandem duplication in the juxtamembrane (JM) domain of the FLT3 (FMS-like tyrosine kinase 3/FLK2, CD135) gene in 94 children with acute myeloid leukemia (AML) and evaluated its correlation with clinical features. Longer polymerase chain reaction (PCR) products were observed in five patients; 1/3 of M0, 119 of M1, 1/39 of M2, 1/9 of M3 and 1/12 of M5. The sequence analyses of abnormal PCR products showed that all the abnormal products were derived from tandem duplications involving the JM domain and that all the lengthened sequences were in-frame as we previously reported. Statistical analyses revealed a significantly lower incidence of the tandem duplication in childhood AML patients than in adult patients (P < 0.05), and significantly shorter disease-free survival in patients with mutant FLT3 than in patients with wild-type FLT3 (P < 0.05). Our results suggest that the tandem duplication in the JM domain of the FLT3 gene is not a frequent phenomenon but might be a factor of poor prognosis in childhood patients with AML.
 ...
PMID:Internal tandem duplication of the FLT3 gene and clinical evaluation in childhood acute myeloid leukemia. The Children's Cancer and Leukemia Study Group, Japan. 1004 58

Studies of murine stem cells suggest that the cytokine receptors Flt3 and c-kit are expressed differentially on the earliest reconstitutional cells, such that Flt3 is not expressed until after stem cell activation. Much less is known about the expression of Flt3 and c-kit on primitive human cells, especially those mobilized into circulation for transplantation. In this study, early circulating precursors were analyzed for expression of Flt3 at the gene and protein levels. Flow cytometric studies showed that >90% of CD34+CD38- cells expressed Flt3 antigen (CD135). The proportion of fresh CD34+ cells expressing Flt3 decreased as CD38 staining increased. These results were confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) analyses, which showed that Flt3 gene expression generally was limited to the CD34+CD38- population. Because Flt3 ligand (FL) enhances the growth and/or maintenance of primitive cells, it was important to know how long early cells retain Flt3 receptor expression in expansion culture. Both RT-PCR analyses and functional tests demonstrated that primitive cells are capable of expressing Flt3 for as long as 2 weeks in liquid medium. During the first week of culture, FL enhanced the generation of cells and progenitors without causing a loss of primitive CD34+CD38-Flt3+ cells. Flt3 expression in cell cultures was limited to precursors retaining a CD34+CD38(-/lo) phenotype. Because the most primitive human precursors are believed to express c-kit at a low level, we examined the FL responsiveness of CD34+CD38-c-kit(-/lo) cells and CD34+CD38-c-kit+ cells. CD34+CD38-c-kit(-/lo), cells constituted a small fraction (12%) of the CD34+CD38- population. Whereas both c-kit(-/lo) and c-kit+ subsets were stimulated by FL, cell expansion (p < 0.01) and colony formation (p < 0.01) were greater and maintained longer with CD34+CD38-c-kit(-/lo) cells. Furthermore, the rapid response to FL suggests that primitive CD34+CD38-c-kit(-/lo) cells express Flt3 at the time of isolation or shortly thereafter. These results demonstrate the presence of Flt3 on CD34+CD38 blood cells and suggests that Flt3 also may be present on a c-kit(-/lo) subset, among the most primitive in circulation. Flt3 is lost during maturation to committed (CD34+CD38+) lineages. Addition of FL to primitive cell cultures stimulates cell expansion while maintaining early CD34+CD38-Flt3+ precursors for at least 7 days. The possible existence of a more primitive CD34+CD38-c-kit(-/lo) Flt3(-/lo) precursor remains to be determined.
 ...
PMID:Expression of Flt3 and c-kit during growth and maturation of human CD34+CD38- cells. 1034 Apr 8

We established three sister cell lines, NALM-30, NALM-31 and NALM-32, with biphenotypic features carrying myeloperoxidase mRNA and protein with complex Philadelphia (Ph) chromosome, t(9;22;10)(q34;q11;q22), from a patient with Ph-positive acute leukemia in relapse. Epstein-Barr virus nuclear antigen was negative. The morphological appearance of the cell lines is that of immature lymphoid cells. Expression of myeloid- and lymphoid-associated surface membrane antigens on these cells was detected allowing for the classification of "biphenotypic" leukemia. Immunophenotypically, the established cell lines reported here fulfill the European Group for the Immunological Characterization of Leukemias (EGIL) criteria for B-lineage derivation, however, surface and cytoplasmic immunoglobulin chains were negative. Whereas TGF-beta R (CD105), MCSFR (CD115), SCFR (CD117), IL-4R/IL-13R (CD124) and IL-6R (CD126) were not expressed, the cell lines were mostly positive for IFN-gamma R (CD119), IL-7R (CD127) and FLT-3R (CD135). The NALM-30, NALM-31 and NALM-32 cell lines together with their serial sister cell lines NALM-27 and NALM-28 which were established from the same patient at diagnosis provide unprecedented opportunities for studying a multitude of biological aspects related to normal and neoplastic immature B-lymphocytes.
 ...
PMID:Myeloperoxidase positive acute lymphoblastic leukemia cell lines, NALM-30, NALM-31 and NALM-32, carrying Philadelphia chromosome with biphenotypic characteristics. 1036 60

The purpose of this report is to demonstrate the expression of very recently identified surface antigens on CD34+ and AC133+ bone marrow (BM) cells. Coexpression analysis of AC133 and defined antigens on CD34+ BM cells revealed that the majority of the CD164+, CD135+, CD117+, CD38low, CD33+, and CD71low cells resides in the AC133+ population. In contrast, most of the CD10+ and CD19+ B cell progenitors and a fraction of the CD71high population are AC133-, indicating that CD34+AC133+ cells are enriched in primitive and myeloid progenitor cells, whereas CD34+AC133- cells mainly consist of B cell and late erythroid progenitors. This corresponds to the highly reduced percentage of CD10+ B cells and the absence of CD71high erythroid progenitors on AC133+ selected BM cells. A portion of 0.2-0.7% of the AC133+ selected cells do not coexpress CD34. These cells are very small and define a uniform CD71-, CD117-, CD10-, CD38low, CD135+, HLA-DRhigh, CD45+ population with unknown delineation. Four color analysis on CD34+CD38- BM cells revealed that virtually all of these primitive cells express AC133. Using an improved liposome-enhanced labeling technique for the staining of weakly expressed antigens, subsets of this population could be identified which express the angiopoietin receptors TIE (67.6%) and TEK (36.8%), the vascular endothelial growth factor receptors FLT1 (7%), FLT4 (3.2%), and KDR (10.4%), or the receptor tyrosine kinases HER-2 (15.4%) and FLT3 (CD135; 77.6%). Our results suggest that the CD34+CD38- population is heterogeneous with respect to the expression of the analyzed receptor tyrosine kinases.
 ...
PMID:Expression of novel surface antigens on early hematopoietic cells. 1037 8

We have studied tissue expression of the cytokine receptors using a high sensitivity biotin-streptavidin system on cryostat sections. We used a panel of monoclonal antibodies from the 6th International Workshop on Human Leukocyte Differentiation Antigens, namely CD25 (IL-2R alpha), CD95 (FAS antigen), CD116 (GM CSFR), CD117 (SCFR), CD120 alpha (TNFR I), CD120b (TNFR II), CD121a (IL-1R I), CDw123 (IL-3R), CD124 (IL-4R), CD126 (IL-6R), CD127 (IL-7R), CDw128 (IL-8R), CD130 (gpl130), CD131 (IL-3R), CD132 (IL-2R gamma), CD134 (OC-40), CD135 (FLT3/FLK2). Examined tissues (lymph nodes and spleens) were obtained from 12 patients with folicular non-Hodgkin's lymphoma, periferal T non-Hodgkin's lymphoma, B lymphoma, myeloma, Hodgkin's disease, two cases of T cell rich B-lymphoma, autoimmune haemolytic anemia and two cases of rudimentary trombocytopenic purpura. Our results indicate that immunohistological technology using native tissues on cryostat sections, monoclonal antibodies and the visualisation with biotin-streptavidin is a particularly suitable supplementary staining procedure for detection of the cytokine receptors in tissues.
 ...
PMID:[Immunohistochemical detection of cytokine receptors on cryostat tissue sections]. 1037 62

The biological effects of flt3-L, and the expression of its tyrosine kinase receptor (flt3, CD135) were investigated on the immature subsets of human circulating peripheral blood progenitors obtained from cancer patients or normal volunteer donors, after mobilization with rhG-CSF or chemotherapy. flt3 was expressed at low levels, and its expression increased concomitantly with expression of CD38 within the CD34+ cell population. Despite this low-level expression, flt3-L exerted synergistic effects with a combination of c-kit ligand, IL-3, IL-6, GM-CSF and G-CSF, mainly to induce proliferation of CD34+/CD38- cells. In addition, flt3-L increased the detection of HPP-CFC, both immediately after cell selection, and after 7 and 14 d of cultures. We conclude that flt3-L is active on circulating early mobilized haemopoietic progenitors, despite the low- level expression of its receptor.
 ...
PMID:Early progenitor cells from human mobilized peripheral blood express low levels of the flt3 receptor, but exhibit various biological responses to flt3-L. 1046 May 91


<< Previous 1 2 3 4 5 6 7 8 9 Next >>