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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Hardy-Zuckerman 4 feline sarcoma virus (HZ4-FeSV), isolated from a feline fibrosarcoma, is a replication defective acute transforming feline retrovirus that originated by transduction of feline c-kit sequences with feline leukemia virus (FeLV). The v-kit sequences of the HZ4-FeSV, a segment of 1106 nucleotides, correspond to sequences of the cytoplasmic domain of the c-kit receptor kinase. The HZ4-FeSV is known to encode an 80-kilodalton protein with FeLV gag and kit determinants. The P80gag-kit protein and its associated activities from HZ4-FeSV-transformed mink cells were characterized. The P80gag-kit protein was found to be myristoylated, suggesting a membrane association for this protein. In agreement with the predicted relationship with tyrosine kinases, by using the in vitro immune complex-kinase procedure, the P80gag-kit protein was shown to display a tyrosine-specific autophosphorylation activity. In vivo, the P80 protein was found to be phosphorylated on serine and threonine and to a lesser degree on tyrosine. In addition, potential in vivo protein substrates for tyrosine-specific phosphorylation mediated by the P80gag-kit kinase were identified in HZ4-FeSV-transformed cells.
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PMID:Tyrosine protein kinase activity of the HZ4-feline sarcoma virus P80gag-kit-transforming protein. 169 69

Expression of the 93-kd tyrosine kinase encoded by the human c-fes proto-oncogene (also known as FES) is restricted to mature hematopoietic cells of the granulocytic and monocytic lineages, suggestive of a function essential to normal myeloid differentiation. However, recent studies have shown that c-fes can transform fibroblasts if sufficient levels of gene expression are achieved. These findings indicate that strict regulation of the c-fes gene is critical to normal myeloid development, whereas elevated c-fes expression may contribute to malignant transformation. In the present study, we compared the c-fes messenger RNA (mRNA) levels in leukemia blasts from patients with myeloid or lymphoid leukemia with those of peripheral monocytes from a normal donor with the use of a quantitative ribonuclease protection assay. The presence of c-fes mRNA was readily detected in both acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) cells, but c-fes mRNA was present in low levels or was absent in lymphoid leukemia cells. The leukemia cells of two of five AML patients and four of four CML patients expressed more c-fes mRNA than monocytes from a normal donor, with more than a threefold elevation in the cells of one CML patient. No evidence of amplification or rearrangement of the c-fes gene was detectable by Southern blot analysis of myeloid leukemia DNA, suggesting that the variation in c-fes mRNA levels are related to differences in transcriptional activity and/or message stability. These results indicate that elevated c-fes expression is a common feature of myeloid leukemia cells that could potentially contribute to the leukemia phenotype.
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PMID:Elevated expression of the c-fes proto-oncogene in adult human myeloid leukemia cells in the absence of gene amplification. 198 16

In the present article, we show that 6 of 69 acute myelogenous leukemia (AML) samples exhibited autonomous in vitro growth that was dependent on endogenous granulocyte-macrophage colony-stimulating factor (GM-CSF). Cytoplasmic RNA harvested from all 6 leukemia specimens contained GM-CSF transcripts easily detectable by mRNA hybridization. All 6 GM-CSF-expressing leukemia samples simultaneously displayed high levels of transcripts for the c-fes proto-oncogene previously shown to be expressed in GM-CSF sensitive myeloid cells, whereas only 2 of the 48 AML samples not expressing GM-CSF accumulated c-fes mRNA. Seven of additional 14 GM-CSF-expressing specimens showed specific signals upon RNA hybridization with the c-fes probe, but failed to grow autonomously. These results suggest that c-fes and GM-CSF genes may be coordinately regulated in AML blasts and that GM-CSF-mediated growth autonomy may be linked to c-fes expression.
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PMID:Expression of the c-fes proto-oncogene in granulocyte-macrophage colony-stimulating factor-dependent acute myelogenous leukemia cells grown autonomously. 201 Jun 59

Studies were conducted to determine the relationship between the pretherapy characteristics of leukemia cells and their behaviour during culture in vitro. Leukemia cells which proliferated well in vitro also proliferated well in vivo. Cells which manifested myeloid or monocytic differentiation in vivo tended to manifest differentiation along these lines in vitro. Cells which manifested high levels of expression of c-fms, c-fes, or triose phosphate isomerase prior to culture were likely to differentiate in vitro, with high levels of c-fes expression being related to myeloid maturation. These observations suggest that differentiation at the molecular level prior to culture is a requisite for leukemia cell differentiation in vitro. The same may be true for differentiation in vivo under the influence of exogenously administered agents such as cytotoxic chemotherapy or recombinant growth factors.
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PMID:Studies of the proliferation and differentiation of immature myeloid cells in vitro: 4: Preculture proto-oncogene expression and the behaviour of myeloid leukemia cells in vitro. 206 34

Sera from 353 cats with naturally occurring feline leukemia virus (FeLV) infection were collected in Boston, Los Angeles, New York City, and Seattle between 1968 and 1988. These sera were retrospectively assayed by enzyme-linked immunosorbent assay for antibodies to feline immunodeficiency virus (FIV). Fifty-one (14.4%) of the FeLV-positive sera had antibodies to FIV, indicating dual oncovirus and lentivirus infections. FIV infections were confirmed by Western blot analysis, antibodies against the 15 and 27 kDa proteins being used as definitive markers. FIV infection was diagnosed in one cat sampled in 1968 and in eight other cats sampled before 1975 in New York City. Illnesses exhibited by coinfected cats were similar to those of cats infected with FeLV only. Two unrelated cats with multicentric fibrosarcomas were found to be simultaneously infected with FIV, FeLV, and feline sarcoma virus. FIV was less contagious than FeLV in 73 cats residing in an exposure household between 1977 and 1980 as determined by evaluation of sera collected sequentially. In this household, 15 resident cats became FeLV infected whereas no cats contracted FIV infection. Comparison of serologic results from 53 cats with leukemia/lymphoma and matched controls confirmed a strong correlation between FeLV viremia and leukemia/lymphoma. A significant correlation between FIV infection and lymphoproliferative malignancies was also found independent of FeLV infection.
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PMID:Feline immunodeficiency virus and feline leukemia virus infections and their relationships to lymphoid malignancies in cats: a retrospective study (1968-1988). 215 93

Activation of the c-abl protooncogene occurs in Abelson murine leukemia virus, in Hardy-Zuckerman 2 feline sarcoma virus, and during the chromosomal translocations that generate BCR-ABL gene fusion products. To study the molecular mechanism involved in the c-abl activation, we have created a series of modifications in murine c-abl and assayed these constructs for oncogenic activity using the NIH 3T3 cell transformation assay. Our results show that amino-terminal deletions are sufficient for oncogenic activation of c-abl and high levels of oncogenic activities were generated by a deletion of 114 codons from the 5' end that deleted the SH3 region. A deletion of 53 codons from the 5' end (inclusive of deletions seen in Hardy-Zuckerman 2 feline sarcoma virus and BCR-ABL gene products) that retains the SH3 region of c-abl resulted in the generation of low levels of transforming activity. This transforming potential was substantially increased with the introduction of a G----A point mutation in codon 832 that is present in v-abl. The point mutation was found to affect the secondary structure and the tyrosine kinase activity of the mutant gene products.
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PMID:Activation of murine c-abl protooncogene: effect of a point mutation on oncogenic activation. 216 50

The McDonough strain of the feline sarcoma virus contains a transforming gene (v-fms) which contains partial nucleotide homology with proto-oncogenes encoding tyrosine kinases. One of the v-fms-encoded products, gp140fms, is a cell surface transmembrane glycoprotein that may function as a growth factor receptor. Although c-fms transcripts have been detected in placental trophoblasts and normal human bone marrow, the role of the c-fms gene product is unknown. We now report that induction of monocytic, but not granulocytic, differentiation of human HL-60 leukaemic cells is associated with expression of c-fms, preceded by that of c-myc and c-fos. Because c-fms transcripts are also detectable in peripheral blood monocytes and in blasts from certain patients with myelomonocytic leukaemia, the c-fms gene product may play a role in monocytic differentiation.
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PMID:Expression of the c-fms proto-oncogene during human monocytic differentiation. 240 50

Physiological inducers of myeloid cell growth and differentiation were used to simultaneously analyze the expression of the proto-oncogenes c-myc, c-myb, c-fos, c-fes and c-fms during normal myelopoiesis, where growth is coupled to differentiation, as compared with that in leukemia, where growth has been uncoupled from differentiation as well as upon suppression of the leukemic phenotype via induction of differentiation and growth arrest. Proto-oncogene expression was also used as a tool to dissect the growth to differentiation developmental cascade. Myeloid cell growth was correlated with high c-myc and c-myb RNA levels, decreasing to undetectable levels in terminally differentiated cells. No c-myc RNA was detected in normal myeloid progenitors induced for differentiation without growth, using media conditioned by mouse granulocytes (GCM), indicating that c-myc may play either no role or an inhibitory one in differentiation. RNA levels of the proto-oncogenes c-fos, c-fes and c-fms were undetectable in normal or M1 differentiation inducible (D+) leukemic myeloblasts, and were stably induced upon stimulation of the normal precursors for growth and differentiation, with highest levels at the time when most of the cells had undergone terminal differentiation. Only c-fes RNA was induced upon M1D+ differentiation. It was also shown to be induced upon induction of differentiation without growth in normal myeloid precursors. Using c-myc and c-myb RNA suppression as molecular markers for induction of M1D+ differentiation, the existence of myeloid differentiation factor(s), distinct from myeloid growth factors, has been demonstrated. Such differentiation inducing activity was found in media conditioned by mouse lungs or granulocytes, and was induced in normal myeloid precursors by the myelopoietic growth factors IL3, GM-CSF, G-CSF, and M-CSF. Taken together, the results of this study enhance and add to previous work to better correlate the expression of the proto-oncogenes myc, myb, fes, fos and fms with several parameters of normal and abnormal myeloid cell growth and differentiation. The results indicate that the normal myeloid growth to differentiation developmental cascade entails a mechanism whereby myeloid growth factors induce myeloid differentiation factors, subsequently suppressing c-myc and c-myb RNA expression, leading to the induction of differentiation and growth arrest, including early accumulation of c-fes RNA followed by accumulation of c-fos and c-fms RNAs. It was also indicated that this cascade is impaired in leukemia.
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PMID:Proto-oncogene expression and dissection of the myeloid growth to differentiation developmental cascade. 247 Nov 31

The c-fms protooncogene encodes the receptor for the colony-stimulating factor 1 of macrophages. Its transforming counterpart, the v-fms oncogene has previously been recognized as the transforming gene of the McDonough strain of feline sarcoma virus. We have isolated rabbit antisera against a 115-kDa recombinant polypeptide containing the 926 carboxy-terminal amino acids of the v-fms protein. All antibodies recognized the cytoplasmic domain of the v-fms protein, which is 95% homologous to the corresponding domain of human c-fms proteins. These sera were applied in a survey of various human cancer cell lines, such as peripheral blood mononuclear (HL60) and choriocarcinoma (BeWo) cells, as well as leukemic cells from 58 patients with acute myelocytic, chronic myelocytic or acute lymphocytic leukemias (AML, CML, ALL). Significantly enhanced levels of fms-specific tyrosine kinase activity were detected in 12-O-tetradecanoylphorbol-13-acetate-induced HL60 and in BeWo cells, and in 7 out of 24 samples from AML patients, whereas no activity could be detected in 9 ALL or in 25 CML cell preparations. The AML cells were classified according to the FAB criteria. The highest incidence of increased fms activity was found in cells assigned to the M4 class (four out of five cases). While no activity was found in material belonging to FAB classes M2 or M3, one of the two cases of the M5 class was kinase-positive. Interestingly, two out of seven cases of the M1 class cells exhibited enhanced levels of fms kinase. These data suggest that the determination of the fms kinase may be useful to subdivide the M1 class of the FAB classification into monocytic and non-monocytic precursor leukemia cells.
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PMID:Detection of fms-oncogene-specific tyrosine kinase activity in human leukemia cells. 252 17

The present study is a detailed computer-assisted analysis of the feline leukemia virus gag gene nucleotide sequence together with its flanking sequences (ST-FeLV GAG) that is compared with the aligned sectors of the Moloney strain of murine leukemia virus (Mo-MuLV GAG) and of three strains of feline sarcoma virus. It shows that perfectly matched repeated oligomers up to 13 nucleotides long are overrepresented and scattered throughout both ST-FeLV GAG and Mo-MuLV GAG, in noncoding and coding sectors, with no stringent correlation to codon usage in ST-FeLV gPr80gag. Many repeated oligomers share a core consensus that is intriguingly part of the inverted repeat at the termini of the long terminal repeat. Local scrambled repetitions of nucleotide subsequences have been found; they suggest a model of molecular evolution by slippage-like mechanisms. Thus, viral genomes could be subject to the same evolutionary mechanisms that are now known to be operating extensively in eukaryotic genomes. The data are discussed in light of putative patterns of molecular evolution.
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PMID:Scrambled duplications in the feline leukemia virus gag gene: a putative pattern for molecular evolution. 255 88


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