Molecular cloning of Snyder-Theilen feline leukemia and sarcoma viruses: comparative studies of feline sarcoma virus with its natural helper virus and with Moloney murine sarcoma virus

Pathological significance and predictive value for biochemical recurrence of c-Fes expression in prostate cancer

BACKGROUND

c-Fes is a proto-oncogene encoded non-receptor protein-tyrosine kinase (PTK). However, genetic studies have indicated that it has anti-tumorigenic effects in certain cancers. The pathological and clinical significance of c-Fes in prostate cancer are unknown.

METHODS

Expression of c-Fes was evaluated in normal glands, prostatic intraepithelial neoplasia (PIN), cancer cells in tissues of knock-in mouse adenocarcinoma prostate (KIMAP) model, and prostate cancer patients free of metastasis. Expression of c-Fes was analyzed by immunohistochemistry, and quantified by using the immunoreactivity score (IRS) (staining intensity × percentage of positive cells). Relationships between c-Fes expression and pT stage, Gleason's score (GS), and biochemical recurrence in patients who underwent radical surgery were also investigated.

RESULTS

In KIMAP, the percentage in normal glands, PIN and cancer cells positive for c-Fes expression were 0 (0/7), 25.0 (2/8), and 100% (7/7), respectively. In human tissues, c-Fes expression was also significantly higher in cancer cells than in normal cells and PIN, and it correlated with pT stage (P < 0.001) and GS (P = 0.047). Multivariate analysis showed that c-Fes expression was an independent predictor of poor outcome poor prognosis (hazard ratio = 3.21, 95% confidence interval = 1.11-9.37, P = 0.032).

CONCLUSION

The results suggested that c-Fes expression is a useful predictor of biochemical recurrence after radical surgery. The results also suggested that c-Fes is a potentially useful therapeutic target in prostate cancer and a predictor of biochemical recurrence after radical prostatectomy.

Fes tyrosine kinase expression in the tumor niche correlates with enhanced tumor growth, angiogenesis, circulating tumor cells, metastasis, and infiltrating macrophages

Fes is a protein tyrosine kinase with cell autonomous oncogenic activities that are well established in cell culture and animal models, but its involvement in human cancer has been unclear. Abundant expression of Fes in vascular endothelial cells and myeloid cell lineages prompted us to explore roles for Fes in the tumor microenvironment. In an orthotopic mouse model of breast cancer, we found that loss of Fes in the host correlated with reductions in engrafted tumor growth rates, metastasis, and circulating tumor cells. The tumor microenvironment in Fes-deficient mice also showed reduced vascularity and fewer macrophages. In co-culture with tumor cells, Fes-deficient macrophages also poorly promoted tumor cell invasive behavior. Taken together, our observations argue that Fes inhibition might provide therapeutic benefits in breast cancer, in part by attenuating tumor-associated angiogenesis and the metastasis-promoting functions of tumor-associated macrophages.

Contributions of F-BAR and SH2 domains of Fes protein tyrosine kinase for coupling to the FcepsilonRI pathway in mast cells

This study investigates the roles of Fer-CIP4 homology (FCH)-Bin/amphiphysin/Rvs (F-BAR) and SH2 domains of Fes protein tyrosine kinase in regulating its activation and signaling downstream of the high-affinity immunoglobulin G (IgE) receptor (FcepsilonRI) in mast cells. Homology modeling of the Fes F-BAR domain revealed conservation of some basic residues implicated in phosphoinositide binding (R113/K114). The Fes F-BAR can bind phosphoinositides and induce tubulation of liposomes in vitro. Mutation of R113/K114 to uncharged residues (RK/QQ) caused a significant reduction in phosphoinositide binding in vitro and a more diffuse cytoplasmic localization in transfected COS-7 cells. RBL-2H3 mast cells expressing full-length Fes carrying the RK/QQ mutation show defects in FcepsilonRI-induced Fes tyrosine phosphorylation and degranulation compared to cells expressing wild-type Fes. This correlated with reduced localization to Lyn kinase-containing membrane fractions for the RK/QQ mutant compared to wild-type Fes in mast cells. The Fes SH2 domain also contributes to Fes signaling in mast cells, via interactions with the phosphorylated FcepsilonRI beta chain and the actin regulatory protein HS1. We show that Fes phosphorylates C-terminal tyrosine residues in HS1 implicated in actin stabilization. Thus, coordinated actions of the F-BAR and SH2 domains of Fes allow for coupling to FcepsilonRI signaling and potential regulation the actin reorganization in mast cells.

Molecular cloning of feline leukemia provirus genomes integrated in the feline large granular lymphoma cells

Feline leukemia virus (FeLV) is a horizontally transmitted agent of the domestic cat which is known to be associated with wide spectrum of diseases of the hematopoietic system. In the present study, proviral DNAs of FeLV proviruses were examined in the tumor cells of natural killer cell lineage which is very rare in cats. In the chromosomal DNA of the tumor cells, 5 distinct bands corresponding to exogenous FeLV provirus genomes were detected by digestion with EcoRI which does not cut most FeLV isolates. Five clones of pLC1, pLC2, pLC3, pLC4, and pLC5 obtained from the 5 respective bands were analysed by restriction endonuclease mapping and Southern blot hybridization using gene-specific probes of FeLV. The results have clearly demonstrated that pLC4 and pLC5 contained large deletions in the pol and part of gag regions, while the full-length proviruses could be observed in pLC1 and pLC2. Furthermore, pLC3 contained part of a variant FeLV genome having an EcoRI site in its gag region. The molecular clones of defective and variant FeLV in this study may be useful for the further examination of tumorigenesis of large granular lymphoma in the cat.

Different pattern of expression of cellular oncogenes in human non-small-cell lung cancer cell lines

Altered and deregulated cellular oncogenes were found in many human solid tumors. Except for a few types of tumors that consistently exhibited specific altered proto-oncogenes, the majority of tumors are associated with a number of transcriptionally activated cellular oncogenes. In the heterologous group of non-small-cell lung cancer (NSCLC), nothing about a specific pattern of proto-oncogene expression is known. Therefore, we investigated the expression of a panel of cellular oncogenes in NSCLC cell lines. DNA and RNA from 11 established NSCLC cell lines (4 adenocarcinoma cell lines, 3 squamous cell carcinoma cell lines, 3 large-cell carcinoma cell lines and 1 mesothelioma cell line) were isolated and analysed using the Southern, dot blot and Northern hybridization technique. c-myc RNA expression was found in all NSCLC cell line, L-myc expression only in 1 adenocarcinoma cell line, N-myc and c-myb expression in none of the 11 cell lines examined. No c-myc amplification could be detected in the DNAs. v-sis-related mRNA was observed in 5/11 cell lines without association to a specific NSCLC subtype. v-src-related mRNA, found in all tested cells, exhibited increased levels in 1 adenocarcinoma cell line (A-549) compared to the other cell lines. Binding sites for epidermal growth factor (EGF) had been described previously in NSCL, therefore we found erbB homologue transcripts coding for the EGF receptor in all NSCLC cell lines. Also, c-raf1-, N-ras-, Ki-ras-, and H-ras-related RNA expression was observed in all lines. We conclude that L-myc, N-myc, and c-myb expression does occur less frequently in NSCLC than in SCLC. Also amplification does not appear to be an important mechanism by which the c-myc proto-oncogene is activated in NSCLC. A specific pattern of oncogene expression could not be detected in NSCLC cells; each cell line examined showed its own pattern. However, transcriptional activation of a proto-oncogene like erbB, ras, raf, src, and c-myc, which are all involved in the progression pathway of EGF, may be a common feature of NSCLC.

Scrambled duplications in the feline leukemia virus gag gene: a putative pattern for molecular evolution

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.

Insulin-like growth factor I receptor gene is concordant with c-Fes protooncogene and mouse chromosome 7 in somatic cell hybrids

The insulin-like growth factor I (IGF-1) mediates the actions of pituitary growth hormone in a variety of tissues. Its receptor (IGF1R) displays considerable structural similarity to the insulin receptor. In humans, the IGF1R gene has been mapped near FES, the cellular counterpart of the feline sarcoma virus transforming gene v-fes, at the q25-q26 region of human chromosome 15 (HSA15). Here, we report the mapping of mouse Igf1r to mouse chromosome 7 (MMU7) by somatic cell hybrid analysis. This result, along with the prior assignment of the loci for mitochondrial isocitrate dehydrogenase and FES to human chromosome 15 and mouse chromosome 7, suggest a conserved autosomal synteny group on the distal long arm of HSA15 and in the center of MMU7.

Human KRAS oncogene expression in meningioma

Expression of 16 oncogenes was investigated in a series of human meningiomas showing a normal chromosome complement or the characteristic monosomy 22 but no structural aberrations detectable by banding analysis. By dot hybridization, the only expressed sequence detected was KRAS. The expression was elevated approximately 6--8-fold in comparison to matrix tissue (meninges) and to fibroblasts of the corresponding patient. Northern blot analysis displayed the typical banding pattern and an 8--10-fold overexpression. DNA analysis did not reveal gene amplification or major rearrangements in the KRAS gene structure.

Construction and quality of cDNA libraries prepared from cytoplasmic RNA not enriched in poly(A)+RNA

Poly(A)+RNA and cytoplasmic RNA of Ehrlich ascites tumor cells grown in vivo were used to study the quality and efficiency of cDNA synthesis. It was found that the rates of oligo(dT)-primed and unprimed reverse transcription were very similar in both cases. The size distributions of the cDNA strands prepared from unfractionated RNA reflected the size of cytoplasmic mRNA populations including a significant fraction of long molecules up to 6 kb. The fraction of cDNAs primed on rRNAs by oligo(dT) was found to be as low as 2-3%. Following second-strand synthesis by means of RNase H-induced nick translation by DNA polymerase I the overall yields in double-stranded cDNA were slightly higher when unfractionated cytoplasmic RNA was used as starting template. In repeated experiments we obtained an average yield of 2.2 micrograms of double-stranded cDNA when 70 micrograms of unfractionated cytoplasmic RNA was used as starting material. This amount of cDNA synthesized in one assay was sufficient to construct representative cDNA libraries in different vectors. Southern hybridizations of DNA isolated from cDNA libraries with various radiolabelled probes show that the libraries constructed from cDNA synthesized from cytoplasmic RNA not enriched in poly(A)+RNA contain a high ratio of full-length cDNA clones. The results suggest that representative cDNA libraries of high quality can be constructed without pre-isolation of poly(A)+RNA fractions.

Transcription of proto-oncogenes in Rous sarcoma virus infected and transformed chicken embryo cells

To evaluate an effect of infection by RSV on the transcriptional activity of proto-oncogenes, we tested 19 cellular oncogenes and the beta-actin gene performing "nuclear run on transcription assays" using nuclei isolated from RSV infected or transformed chick embryo cells (CEC). A drastic increase in the transcriptional activity of the c-fgr proto-oncogene and a slight increase of c-fos and c-myc could be observed in uninfected compared to RSV infected CEC. To distinguish between infection- and transformation-dependent alterations we used the transformation-defective temperature-sensitive RSV mutant strain NY 68. Ts NY 68 infected CEC maintained at the permissive temperature of 36 degrees C and exhibiting a transformed phenotype, displayed no significant differences in the transcriptional activity of the 19 proto-oncogenes when compared to ts NY 68 infected CEC maintained at the nonpermissive temperature of 42 degrees C and exhibiting a normal phenotype. We conclude that the alterations observed were caused by the viral infection and are not due to the process of transformation. No significant changes in the transcription rate of the investigated genes could be observed after shifting ts NY 68 infected CEC from 42 degrees C to 36 degrees C. In contrast, a shift of ts NY 68 infected CEC from 36 degrees C to 42 degrees C results, after 2 hours, in a transient increase of the c-fos transcription.

Oncogene expression in related cancer lines differing in metastatic capacity

Various murine tumor cell lines with different metastatic capacities were tested in vitro for oncogene expression, especially of the p21-Ha-ras protein. Small differences were seen in the expression of several distinct oncogenes in the case of a high metastatic lymphoma variant (ESb) and its low metastatic parental line (Eb). In one instance we observed a 30-fold Ha-ras gene amplification in a metastasis-derived cell line from a spontaneous mouse mammary carcinoma. In spite of this amplification we did not find an increased p21 expression in these cells.

Oncogene expression in T-cell lymphoproliferative disorders

We have investigated the expression of oncogenes and other related genes in eleven patients with T-cell lymphoproliferative disorders and ten patients with other hematologic malignancies. The phenotypes of the T-cell disorders were determined using monoclonal antibodies specific for helper or suppressor subsets. RNA preparations were isolated from peripheral blood mononuclear cells and/or lymph node sections, 5'-end labeled with gamma-32P-ATP, and hybridized under stringent conditions to an excess of nitrocellulose-bound specific cloned DNA; autoradiographs were analysed by microdensitometry. Results revealed increased expression of K-ras, v-fps, transferrin receptor, alpha-tubulin and alpha-interferon in at least five of six helper T-cell lymphoproliferative disorders, while five of five suppressor T-cell disorders demonstrated levels of hybridization to these clones no higher than background. However, studies of T-suppressor disorders demonstrated enhanced levels of beta-interferon-specific RNA in five of five patients, an increase apparent in three of six T-helper chronic lymphoproliferative disorders. These results demonstrate different patterns of gene expression evident in T-helper and T-suppressor abnormalities.

Structure and origins of the HZ2-feline sarcoma virus

The HZ2-feline sarcoma virus (HZ2-FeSV) is a replication-defective acute transforming feline retrovirus with oncogene homology to Abelson murine leukemia virus (A-MuLV) (P. Besmer, W.D. Hardy,Jr., E. E. Zuckerman, P. J. Bergold, L. Lederman, and H. W. Snyder, Jr. (1983) Nature (London) 303, 825-828). In contrast to A-MuLV which was isolated from a hematopoietic tumor, the HZ2-FeSV derives from a multicentric fibrosarcoma. We have molecularly cloned the HZ2-FeSV provirus from mink HZ2-FeSV nonproducer cells. The molecularly cloned HZ2-FeSV provirus is biologically active upon transfection of NIH 3T3 indicator cells. The genetic structure of the HZ2-FeSV provirus was determined by EM heteroduplex and Southern blot analysis. The HZ2-FeSV has a 6.8 kb-viral genome with the structure: 5' delta gag-abl-delta pol-delta env 3'. The abl insert, which is 1.4 kb, is located 1.9 kb from the 5' end and 3.5 kb from the 3' end of the viral genome. The 5' 1.9 kb in the HZ2-FeSV are colinear with 5' FeLV sequences, and the 3' 3.5 kb are colinear with 3' FeLV sequences, with the exception of a 0.85-kb deletion in the env gene. HZ2-FeSV v-abl and A-MuLV v-abl share 1.2 kb of abl sequences which are known to specify the protein kinase domain of the abl gene product and are necessary for fibroblast transformation in vitro. The DNA from several tumor tissues of cat 3590 from which the HZ2-FeSV was obtained was found to contain several HZ2-FeSV-related proviruses including the HZ2-FeSV. The variant HZ2-FeSVs have indistinguishable 5' gag-abl sequences; however, they differ in 3' sequences which likely do not include any abl sequences. The DNAs from fibrosarcomas obtained by inoculation of kittens with tumor extract were found to contain variant HZ2-FeSV proviruses as well. Taken together these results indicate a role for the HZ2-FeSVs in sarcomagenesis.

Monoclonal antibodies to the v-fes product and to feline leukemia: virus P27 interspecies-specific determinants encoded by feline sarcoma viruses

Monoclonal antibodies to p27 gag and v-fes specific determinants on the gag-onc poly-protein encoded by Snyder-Theilen feline sarcoma virus (ST-FeSV) were prepared. In order to obtain hybridoma clones specific to the antigenic determinants encoded by the FeSV genome, Lou rats were immunized with ST-FeSV-transformed, virus-nonproducing syngeneic cells, and boosted with either the same cells or affinity-purified feline leukemia virus (FeLV) p27. Three distinct clones reactive to both FeLV p27 and p85gag-fes, and one clone specific for a p85fes determinant were established. The anti-p27 monoclonal antibodies also reacted with the polyproteins p95gag-fes and p83gag-fgr, from Gardner-Arnstein (GA) and Theilen-Pedersen (TP1) FeSV, respectively. The anti-p27 monoclonal antibodies reacted with MuLV p30 and RD114 p28 but not with RSV, MMTV, or BLV. These results indicated that the part of the p27 gag gene that is preserved in ST-, GA, and TP1-FeSV encodes interspecies-specific p27 determinants.

Molecular cloning, expression, and chromosomal localization of the gene encoding a human myeloid membrane antigen (gp150)

DNA from a tertiary mouse cell transformant containing amplified human sequences encoding a human myeloid membrane glycoprotein, gp150, was used to construct a bacteriophage lambda library. A single recombinant phage containing 12 kilobases (kb) of human DNA was isolated, and molecular subclones were then used to isolate the complete gp150 gene from a human placental genomic DNA library. The intact gp150 gene, assembled from three recombinant phages, proved to be biologically active when transfected into NIH 3T3 cells. Molecular probes from the gp150 locus annealed with a 4.0-kb polyadenylated RNA transcript derived from human myeloid cell lines and from tertiary mouse cell transformants. The gp150 gene was assigned to human chromosome 15, and was subchromosomally localized to bands q25-26 by in situ hybridization. The chromosomal location of the gp150 gene coincides cytogenetically with the region assigned to the c-fes proto-oncogene, another human gene specifically expressed by myeloid cells.

A new acute transforming feline retrovirus with fms homology specifies a C-terminally truncated version of the c-fms protein that is different from SM-feline sarcoma virus v-fms protein

The HZ5-feline sarcoma virus (FeSV) is a new acute transforming feline retrovirus which was isolated from a multicentric fibrosarcoma of a domestic cat. The HZ5-FeSV transforms fibroblasts in vitro and is replication defective. A biologically active integrated HZ5-FeSV provirus was molecularly cloned from cellular DNA of HZ5-FeSV-infected FRE-3A rat cells. The HZ5-FeSV has oncogene homology with the fms sequences of the SM-FeSV. The genome organization of the 8.6-kilobase HZ5-FeSV provirus is 5' delta gag-fms-delta pol-delta env 3'. The HZ5-and SM-FeSVs display indistinguishable in vitro transformation characteristics, and the structures of the gag-fms transforming genes in the two viruses are very similar. In the HZ5-FeSV and the SM-FeSV, identical c-fms and feline leukemia virus p10 sequences form the 5' gag-fms junction. With regard to v-fms the two viruses are homologous up to 11 amino acids before the C terminus of the SM-FeSV v-fms protein. In HZ5-FeSV a segment of 362 nucleotides then follows before the 3' recombination site with feline leukemia virus pol. The new 3' v-fms sequence encodes 27 amino acids before reaching a TGA termination signal. The relationship of this sequence with the recently characterized human c-fms sequence has been examined. The 3' HZ5-FeSV v-fms sequence is homologous with 3' c-fms sequences. A frameshift mutation (11-base-pair deletion) was found in the C-terminal fms coding sequence of the HZ5-FeSV. As a result, the HZ5-FeSV v-fms protein is predicted to be a C-terminally truncated version of c-fms. This frameshift mutation may determine the oncogenic properties of v-fms in the HZ5-FeSV.

Molecular analysis of several classes of endogenous feline leukemia virus elements

Five recombinant DNA clones of endogenous feline leukemia virus-related DNA sequences were isolated by screening a lambda phage genomic library of cat placental DNA with a probe specific to the gag-pol region of infectious feline leukemia virus. The clones containing retroviral long terminal repeat-like sequences demonstrated the existence of different size classes of endogenous elements in the cat genome, including those of nearly full length in which the gag region is heterogeneous but all of pol and most of env are highly conserved. Other size classes included elements with major deletions in gag or pol. A genomic DNA analysis suggested that the majority of endogenous elements were close to full length in size and that the highly truncated sequences which we described previously (Soe et al., J. Virol. 46:829-840, 1983) represented only a subset of the elements present. A restriction analysis of genomic DNA suggested a high degree of conservation in pol and the 5' portion of env among the various endogenous sequences present in the cat genome. We also found by using DNA transfection that while all of the endogenous clones were noninfectious, there was differential expression of the elements which we examined. These findings correlate with the subgenomic expression of endogenous feline leukemia virus sequences in cat placental tissue.

Oncogene expression in murine splenic T cells and in murine T-cell neoplasms

The differential expression of a series of proto-oncogenes has been examined in a group of cultured murine T-cell lymphomas that were induced following virus inoculation into, or X irradiation of, C57BL/6 mice. Two classes of T lymphoma cell lines were studied: growth factor-dependent (autocrine) cells, and growth factor-independent T lymphoma cells. Cell lines that were established from X-irradiation-induced T lymphomas were growth factor dependent, whereas T lymphoma lines grown from virus-induced tumors were generally growth factor independent. Of 18 cellular proto-oncogenes studied, five (c-myc, c-myb, c-abl, c-rasHa, c-rasKi) were consistently expressed in all cell lines tested. Thirteen other proto-oncogenes (c-mos, c-sis, c-rel, c-yes, c-fes3, c-fes4, c-fos, c-fms, c-src, c-erbA, c-erbB, int-1, Pim-1) were not expressed in any of the T lymphoma cells tested. Concanavalin A-stimulated spleen cells, representative of replicating T cells, expressed c-myc, c-abl, and Pim-1, suggesting that the products of these proto-oncogenes are involved in T-cell proliferation. The results indicate no qualitative differences (albeit some quantitative differences) in proto-oncogene expression between the growth factor-dependent and growth factor-independent cells. This suggests that expression of the five proto-oncogenes is in itself not sufficient to induce the progression of the growth factor-dependent cells to their fully growth factor-independent counterparts. Changes in the regulation of one or more of the five active proto-oncogenes, i.e., from an inducible to a constitutive state, and/or additional changes in the expression of other cellular genes may be required to induce the transformation of neoplastic T cells from growth factor dependence to growth factor independence.

Developmental and molecular aspects of nephroblastomas induced by avian myeloblastosis-associated virus 2-O

Avian myeloblastosis-associated virus-induced nephroblastomas are tumors consisting mainly of mesenchymal and epithelial renal elements with variable degrees of differentiation. The spatial distribution of developmental stages reflects a gradient of differentiation from less differential structures in the periphery towards more differentiated structures in the center of the lobules formed in the nephroblastomas. These heterogenic tumors contain discrete virus-cell DNA junction fragments and are therefore clonal outgrowths of a single transformed cell. These findings support the hypothesis that a mesenchymal, nephrogenic cell residual in the postembryonic kidney is the origin of the tumor, which grows by proliferation and differentiation of this target cell. All the tumors expressed higher levels of viral genomic and env messages than nontransformed tissue from the same kidney. A screening of oncogene expression with 13 different oncogenes revealed enhanced myc levels. There was, however, no rearrangement of c-myc or of the other oncogenes detected with EcoRI-digested tumor DNAs. This suggests that there is no insertion of viral elements adjacent to a c-myc. The levels of myc expression in embryonic kidneys were as high as in the tumors. Therefore, the enhanced myc expression in nephroblastomas is a reflection of the embryonic status of the tumor rather than a newly acquired function. This finding, plus the similarity of development and morphology of nephroblastomas and embryonic kidneys, suggests that the tumors arise as a result of a deficiency in a function which turns the embryonic status off.

Oncogenes and linkage groups: conservation during mammalian chromosome evolution

Proto-oncogenes, which represent the cellular progenitors of the transforming genes harbored by acute transforming oncogenic retroviruses, have been highly conserved during vertebrate evolution. In this report, we have assigned experimentally a subset of proto-oncogenes (SRC, ABL, FES, and FMS-all related to the SRC family) to Chinese hamster chromosomes by Southern filter hybridization analyses of DNAs isolated from both somatic cell hybrids and flow-sorted hamster chromosomes. These results demonstrate that several autosomal linkage groups containing proto-oncogenes originated prior to the radiation and speciation of mammals and have remained remarkably stable for nearly 80 million years.

Characterization of tumor cell lines from a spontaneous rat sarcoma expressing an endogenous retrovirus

We have characterized various biologic, immunologic and growth properties of several cell lines established from a spontaneous rat sarcoma that was discovered more than 60 yr ago. The tumors consisted of mixed cell types with no detectable host cellular immune response. Cultures derived from single-cell clones of the parental cell line were non-invasive but highly tumorigenic even in adult rats. The cultured cells spontaneously released replication-competent endogenous rat type C virus which did not carry a transforming gene in its genome. Since normal cells from the same rat strain did not produce a retrovirus, it is possible that production of the endogenous retrovirus may have triggered specific cellular changes necessary for the oncogene expression and development of this tumor.

Expression of cellular oncogenes during embryonic and fetal development of the mouse

Cellular oncogenes are conserved with great fidelity across a broad span of evolution. This avid conservation suggests possible roles in critical physiologic functions. Little, however, is known about their activity in normal cellular processes. In this study, we examined the expression pattern of eight cellular oncogenes during embryonic and fetal development of the mouse. Five of these genes (c-myc, c-erb, c-Ha-ras, c-src, and c-sis) were expressed at appreciable levels, and four were modulated in a consistent manner during the course of prenatal development.

Nucleotide sequence of the gag gene and gag-pol junction of feline leukemia virus

The nucleotide sequence of the gag gene of feline leukemia virus and its flanking sequences were determined and compared with the corresponding sequences of two strains of feline sarcoma virus and with that of the Moloney strain of murine leukemia virus. A high degree of nucleotide sequence homology between the feline leukemia virus and murine leukemia virus gag genes was observed, suggesting that retroviruses of domestic cats and laboratory mice have a common, proximal evolutionary progenitor. The predicted structure of the complete feline leukemia virus gag gene precursor suggests that the translation of nonglycosylated and glycosylated gag gene polypeptides is initiated at two different AUG codons. These initiator codons fall in the same reading frame and are separated by a 222-base-pair segment which encodes an amino terminal signal peptide. The nucleotide sequence predicts the order of amino acids in each of the individual gag-coded proteins (p15, p12, p30, p10), all of which derive from the gag gene precursor. Stable stem-and-loop secondary structures are proposed for two regions of viral RNA. The first falls within sequences at the 5' end of the viral genome, together with adjacent palindromic sequences which may play a role in dimer linkage of RNA subunits. The second includes coding sequences at the gag-pol junction and is proposed to be involved in translation of the pol gene product. Sequence analysis of the latter region shows that the gag and pol genes are translated in different reading frames. Classical consensus splice donor and acceptor sequences could not be localized to regions which would permit synthesis of the expected gag-pol precursor protein. Alternatively, we suggest that the pol gene product (RNA-dependent DNA polymerase) could be translated by a frameshift suppressing mechanism which could involve cleavage modification of stems and loops in a manner similar to that observed in tRNA processing.

Expression of cellular oncogenes in human malignancies

Cellular oncogenes have been implicated in the induction of malignant transformation in some model systems in vitro and may be related to malignancies in vivo in some vertebrate species. This article describes a study of the expression of 15 cellular oncogenes in fresh human tumors from 54 patients, representing 20 different tumor types. More than one cellular oncogene was transcriptionally active in all of the tumors examined. In 14 patients it was possible to study normal and malignant tissue from the same organ. In many of these patients, the transcriptional activity of certain oncogenes was greater in the malignant than the normal tissue. The cellular fes (feline sarcoma) oncogene, not previously known to be transcribed in mammalian tissue, was found to be active in lung and hematopoietic malignancies.

Nucleotide sequences of the envelope genes of two isolates of feline leukemia virus subgroup B

We determined the nucleotide sequences of the envelope genes of the Snyder-Theilen and Gardner-Arnstein isolates of feline leukemia virus subgroup B. Comparison of the deduced amino acid sequences of the envelope gene products revealed regions of sequence divergence, which we relate to structural features of the viral protein. We also examined nucleotide sequences within the long terminal repeats of these related isolates of feline leukemia virus subgroup B.

Nucleotide sequence of the feline retroviral oncogene v-fms shows unexpected homology with oncogenes encoding tyrosine-specific protein kinases

The nucleotide sequence encoding the transforming polyprotein of the McDonough strain of feline sarcoma virus was determined. This sequence includes 231 nucleotides specifying a leader peptide, 1,377 nucleotides encoding most of the feline leukemia virus-derived gag gene, and 2,969 nucleotides representing the viral transforming gene v-fms. A single open reading frame was predicted to encode a fusion polyprotein of 160,000 daltons (P160gag-fms). Fourteen potential sites for glycosylation were predicted within the v-fms-encoded portion of the protein, consistent with previous observations that the primary translation product is rapidly glycosylated. The presence of hydrophobic signal peptides within the amino-terminal leader sequence and in the middle of the v-fms-encoded moiety suggests that the transforming glycoprotein becomes oriented with its amino terminus within the lumen of the rough endoplasmic reticulum and its carboxyl terminus protruding across the membrane of the rough endoplasmic reticulum into the cytoplasm. The latter portion of the protein shows unexpected homology to tyrosine-specific protein kinases encoded by several of the known retroviral oncogenes.

Infection with feline leukemia virus associated with induction of humoral response to a normal cell protein

Selected populations of cats that were naturally exposed to the feline leukemia virus (FeLV) were found to have humoral antibodies to a normal cell protein designated NCP105. Earlier studies revealed that cats exposed to FeLV often had serum antibodies to the feline oncornavirus-associated cell membrane (FOCMA) as well as to a feline sarcoma virus (FeSV) -specific transforming protein designated gag-fes. Cats with no history of exposure to FeLV or FeSV lacked antibodies to all three antigens: NCP105, FOCMA, and gag-fes. Following exposure to FeLV, cats develop antibodies to either NCP105 or to gag-fes and FOCMA, but not to both groups of antigens. NCP105 is present in both normal and transformed cells from a wide variety of species. It lacks peptide homology with gag-fes and it is not a phosphoprotein. The presence of antibodies to NCP105 in cats exposed to FeLV but not in unexposed cats suggests that FeLV may activate the NCP105 gene or increase the relative immunogenicity of this protein in vivo.

Molecular cloning of integrated Gardner-Rasheed feline sarcoma virus: genetic structure of its cell-derived sequence differs from that of other tyrosine kinase-coding onc genes

Gardner-Rasheed feline sarcoma virus (GR-FeSV) is an acute transforming retrovirus which encodes a gag-onc polyprotein possessing an associated tyrosine kinase activity. The integrated form of this virus, isolated in the Charon 21A strain of bacteriophage lambda, demonstrated an ability to transform NIH/3T3 cells at high efficiency upon transfection. Foci induced by GR-FeSV DNA contained rescuable sarcoma virus and expressed GR-P70, the major GR-FeSV translational product. The localization of long-terminal repeats within the DNA clone made it possible to establish the length of the GR-FeSV provirus as 4.6 kilobase pairs. The analysis of heteroduplexes formed between lambda feline leukemia virus (FeLV) and lambda GR-FeSV DNAs revealed the presence of a 1,700-base-pair FeLV unrelated segment, designated v-fgr, within the GR-FeSV genome. The size of this region was sufficient to encode a protein of approximately 68,000 daltons and was localized immediately downstream of the FeLV gag gene coding sequences present in GR-FeSV. Thus, it is likely that this 1.7-kilobase-pair stretch encodes the onc moiety of GR-P70. Utilizing probes representing v-fgr, we detected homologous sequences in the DNAs of diverse vertebrate species, implying that v-fgr originated from a well-conserved cellular gene. The number of cellular DNA fragments hybridized by v-fgr-derived probes indicated either that proto-fgr is distributed over a very large region of cellular DNA or represents a family of related genes. By molecular hybridization, v-fgr was not directly related to the onc genes of other known retroviruses having associated tyrosine kinase activity.

Human cytomegalovirus (strain AD169) contains sequences related to the avian retrovirus oncogene v-myc

We have detected nucleotide sequences related to the transforming gene (v-myc) of avian myelocytomatosis virus MC-29 in the DNA genome of human cytomegalovirus (HCMV) strain AD169. Cloned DNA representing the entire 1.5-kilobase-pair oncogene v-myc and subfragments of this gene were hybridized to EcoRI-cleaved HCMV virion DNA and cloned subgenomic HCMV DNA fragments. Only a 0.5-kilobase-pair Pst I-Sal I subfragment representing the 5' end of the coding sequence of the v-myc oncogene hybridized to the HCMV DNA. We have localized these v-myc-related sequences to five regions in the long unique segment of the HCMV genome corresponding to EcoRI fragments C, I, P, R, and b and to regions within the EcoRI junction fragments F and H at or near the repeats bounding the short unique segment. There was no hybridization of these HCMV sequences to other retroviral oncogenes tested including v-src, v-myb, v-erb, v-ST-fes, v-fos, v-ras (Harvey), v-mos, and v-abl.

The Hardy-Zuckerman 2-FeSV, a new feline retrovirus with oncogene homology to Abelson-MuLV

There is substantial evidence that oncogenes (v-onc) of acute transforming retroviruses have been acquired by transduction of cellular genes (c-onc) with retroviruses. Feline leukaemia virus (FeLV)-associated feline fibrosarcomas have proven to be extremely useful for the isolation of acute transforming retroviruses of a mammalian species. Three different v-onc genes have been identified in five acute transforming feline retroviruses. The Susan McDonough feline sarcoma virus (SMFeSV) contains the oncogene fms (ref. 4). The Snyder-Theilen (ST) and Gardner-Arnstein (GA) FeSVs contain the oncogene fes (ref. 4), which is homologous to the oncogene fps of the avian sarcoma viruses FSV, RRCII, PRCIV and 16L (refs 7, 8). The v-onc sequences of the Parodi-Irgens (PI) FeSV have recently been found to be homologous with the v-sis sequences of the simian sarcoma virus. We report here the isolation of another acute transforming feline retrovirus from a naturally occurring feline fibrosarcoma, designated the Hardy-Zuckerman 2 feline sarcoma virus (HZ2-FeSV) and demonstrate that the HZ2-FeSV and Abelson murine leukaemia virus (A-MuLV) have homologous oncogenes.

Molecular cloning and characterization of endogenous feline leukemia virus sequences from a cat genomic library

Recombinant bacteriophage lambda clones from a cat genomic library derived from placental DNA of a specific pathogen-free cat were screened to identify endogenous feline leukemia virus (FeLV) sequences. Restriction endonuclease mapping of four different clones indicates that there are a number of similarities among them, notably the presence of a 6.0- to 6.4-kilobase pair (kbp) EcoRI hybridizing fragment containing portions of sequences homologous to the gag, pol, env, and long terminal repeat-like elements of the infectious FeLV. The endogenous FeLV sequences isolated are approximately 4 kbp in length and are significantly shorter than the cloned infectious FeLV isolates, which are 8.5 to 8.7 kbp in length. The endogenous elements have 3.3- to 3.6-kbp deletions in the gag-pol region and approximately 0.7- to 1.0-kbp deletions in the env region. These deletions would render them incapable of encoding an infectious virus and may therefore be related to the non-inducibility of FeLV from uninfected cat cells and the subgenomic expression of these endogenous sequences in placental tissue. It appears that there is conservation in the ordering of restriction sites previously reported in the proviruses of the infectious FeLVs in sequences corresponding to the pol and env boundary as well as the region spanning the env gene of the endogenous clones, whereas a greater divergence occurs among restriction sites mapped to the gag and part of the pol regions of the infectious FeLV. Such deleted, FeLV-related subsets of DNA sequences could have originated either by germ-line integration of a complete ecotropic virus followed by deletion, or by integration of a preexisting, defective, deleted variant of the infectious virus.

Cellular immune response in the blood of cats is restricted to autochthonous feline sarcoma virus-transformed cells

The blood-borne cytotoxic cellular immune response of cats to autochthonous fibroblasts transformed with feline sarcoma virus (FeSV) was examined. Peripheral blood lymphocytes (PBL) from immune animals were assayed for cytotoxic activity using a 51Cr release microcytotoxicity assay. The time courses for appearance of cytotoxic cells were similar for all cats: effector lymphocytes appeared in the blood 7 days after immunization; peak activity occurred about day 16, and cytotoxic PBL were no longer detectable by 35 days. The specificity of cytotoxic lymphocytes was studied using autochthonous and allogeneic targets. PBL from each of five immunized cats killed autochthonous transformed fibroblast (ATF) targets, but the immune lymphocytes were not cytotoxic for non-transformed autochthonous fibroblasts, for allogeneic fibroblasts transformed with FeSV, or for an allogeneic lymphoma cell line which produces feline leukemia virus (FeLV). Specific restriction of target-cell killing to the ATF occurred at all effector:target-cell ratios tested, and was maintained throughout prolonged assay incubation periods. The results suggest that for cytotoxicity to occur it is necessary for the immune lymphocytes to recognize a combination of virus-associated antigens and "self" antigens on the ATF. The similarities between this restricted killing and that caused by cytotoxic T lymphocytes in other mammalian systems are discussed.

The Parodi-Irgens feline sarcoma virus and simian sarcoma virus have homologous oncogenes, but in different contexts of the viral genomes

We have identified the oncogene and the putative transforming protein of the Parodi-Irgens feline sarcoma virus (PI-FeSV). The PI-FeSV is defective and needs a helper virus for its replication. The v-onc sequences in the PI-FeSV were found to be related to the v-sis sequences of the simian sarcoma virus (SSV). PI-FeSV nonproducer cells express two viral RNAs, a 6.8-and a 3.3-kilobase RNA. The 6.8-kilobase RNA contains gag, sis, and env sequences but lacks the pol gene. The 3.3-kilobase RNA, on the other hand, contains only env sequences. We have detected one feline leukemia virus-related protein product in these cells, namely, a 76-kilodalton protein which contains determinants of the feline leukemia virus gag proteins p15 and p30. The v-sis sequences in the PI-FeSV have been located near the 5' end of the viral genome. Taken together, these results imply that the p76 protein contains both feline leukemia virus gag and sis sequences and probably is the transforming protein of this virus. In contrast, in SSV the sis sequences are located towards the 3' end of the viral genome, and the sis protein is thought to be expressed via a subgenomic RNA. PI-FeSV and SSV therefore use different schemes to express their onc-related sequences. The v-sis sequences in the PI-FeSV contain restriction sites which reflect the different origin of the v-sis sequences in the PI-FeSV and SSV. The homologous oncogenes of the PI-FeSV and SSV thus were transduced by two different retroviruses, feline leukemia virus and the simian sarcoma-associated virus, apparently from the genomes of different species.

Mutant feline sarcoma proviruses containing the viral oncogene (v-fes) and either feline or murine control elements

The sequences required for transformation by the Gardner-Arnstein (GA) strain of feline sarcoma virus (GA-FeSV) were defined by site-directed, in vitro mutagenesis of molecularly cloned proviral DNA. Portions of the Ga-FeSV provirus, subcloned in the plasmid pBR322, were mutagenized by deletion or frameshift at XhoI restriction sites flanking the nucleotide sequences presumed to encode the GA-FeSV transforming polyprotein (P108(gag-fes)). The biological activity of subgenomic and reconstructed full-genome-length molecules was assayed by transfection and focus induction in NIH 3T3 cells. Both mutant and wild-type molecules containing the intact P108(gag-fes) coding region induced foci of transformed cells at efficiencies between 10(4) and 10(5) focus-forming units per pmol of DNA; a deletion mutant lacking 3'-terminal v-fes sequences was completely nontransforming in parallel assays. Representative subcloned foci of transformed NIH 3T3 cells synthesized P108(gag-fes) with associated in vitro protein kinase activity. Focus-forming viruses could be rescued from transformed subclones induced by full-length proviral DNA, but not from cells transformed by subgenomic DNA lacking a 3' long terminal repeat (LTR). It was concluded that: (i) nucleotide sequences encoding P108(gag-fes) and its associated kinase activity are responsible for transformation, (ii) the GA-FeSV 3' env and LTR sequences are not required for focus induction, and (iii) the 3' LTR is necessary for rescue of infectious FeSV RNA. A chimeric DNA containing the 5' LTR and P108(gag-fes) coding region of GA-FeSV joined to the 3' LTR of Moloney murine sarcoma virus was both transforming and rescuable at high efficiency. Restriction analysis showed that passaged stocks of rescued transforming virus contained Moloney murine sarcoma virus U3 sequences at both proviral DNA termini, consistent with generally accepted models for LTR formation during reverse transcription. Wild-type GA-FeSV and the chimeric virus (here designated as GAHT), each rescued from NIH 3T3 cells with the same amphotropic murine leukemia virus, yielded approximately equal numbers of foci when titrated on CCL 64 mink cells. By contrast, on mouse NIH 3T3 cells, the focus-forming titer of GAHT was 1 to 2 log higher than that of FeSV. The foci induced on NIH 3T3 cells by GAHT appeared earlier and were reproducibly larger than those induced by GA-FeSV. Differences in transforming activity on NIH 3T3 cells were also found using colony formation in agar, showing that the more rapid appearance and larger size of foci formed in liquid media were not due to virus spread. These data suggest that transcriptional control signals within the viral LTR regulate the levels of the transforming gene product in a species-specific manner.

Antibodies of predetermined specificity detect two retroviral oncogene products and inhibit their kinase activities

Oligopeptides predicted from the nucleotide sequence of the oncogene v-fes of feline sarcoma virus (FeSV) were synthesized chemically and used to generate specific antibodies. Antisera against a 12-amino-acid-long oligopeptide (12-mer) located 42 residues from the carboxyl terminus of the v-fes coding sequence efficiently recognized the transforming proteins encoded by Snyder-Theilen (ST) and Gardner-Arnstein (GA) strains of FeSV. This 12-mer also contains 10 amino acid residues homologous in order and position to those predicted from the nucleotide sequence of the oncogene v-fps of avian Fujinami sarcoma virus (FSV). The anti-12-mer immunoprecipitated the FSV-specific transforming protein molecules from FSV-transformed cells. Binding of these antipeptide antibody molecules to the v-fes and the v-fps gene products inhibited their associated tyrosine-specific protein kinase (EC 2.7.1.37) activities. The ability to generate such site-specific antisera to the products of related oncogenes will be valuable in the molecular characterization of retroviral transforming proteins and their normal cellular homologs.

Feline sarcoma virus-specific transformation-related proteins and protein kinase activity in tumor cells

Polyproteins (gag-fes) encoded by the Synder-Theilen (ST) and the Gardner-Arnstein (GA) strains of feline sarcoma virus (FeSV) were previously shown to be associated with mink or rat cells that were nonproductively transformed in vitro. In the present study we demonstrated that the same gag-fes proteins were found in cat cells transformed in vitro. Of greater importance, these transformation-related proteins were also in cells taken from fresh biopsies of FeSV-induced tumors. Cells from fibrosarcomas induced with ST-FeSV had gag-fes proteins that were characteristic of this strain. Fibrosarcomas and melanomas were induced with GA-FeSV and both types of tumors contained the protein that is characteristic of cells transformed in vitro with this virus. Expression of these proteins in cultured tumor cells appeared to be independent of the passage level. Based on two-dimensional tryptic peptide analysis, the gag-fes proteins of cat tumor cells appeared to be indistinguishable from those found in cells transformed in vitro. The polyproteins of the cat tumor cells have a closely associated protein kinase activity, as demonstrated in the in vitro assay, and phosphorylated tyrosine residues. Gag-fes proteins of either the ST or GA class were not present in cell cultures initiated from five spontaneous cat tumors.

Nucleotide sequences of feline sarcoma virus long terminal repeats and 5' leaders show extensive homology to those of other mammalian retroviruses

The nucleotide sequences of the Gardner-Arnstein feline sarcoma virus (FeSV) long terminal repeat and the adjacent leader sequences 5' to the viral gag gene were determined. These were compared with homologous portions of Synder-Theilen FeSV and with previously published sequences for Moloney murine sarcoma virus and simian sarcoma virus proviral DNA. More than 75% of the residues in the FeSV R and U5 regions were homologous to sequences within the same regions of the other viral long terminal repeats. Unexpectedly, alignment of the FeSV sequences with those of the Moloney murine sarcoma and simian sarcoma viruses showed similar extents of homology within U3. The homologous U3 regions included the inverted repeats, a single set of putative enhancer sequences, corresponding to a "72-base-pair" repeat, and sequences, including the CAT and TATA boxes, characteristic of eucaryotic promotors. The 5' leader sequences of both FeSV strains included a binding site for prolyl tRNA and a putative splice donor sequence. In addition, the FeSV leader contained a long open reading frame which was adjacent to and in phase with the ATG codon at the 5' end of the FeSV gag gene. The open reading frame could code for a signal peptide of about 7.4 kilodaltons. Our results support the concept that the virogenic portions of both FeSV and simian sarcoma virus were ancestrally derived from viruses of rodent origin, with conservation of regulatory sequences as well as the viral structural genes.

Myristyl amino-terminal acylation of murine retrovirus proteins: an unusual post-translational proteins modification

The primary structure of the NH(2)-terminal region of the gag gene encoded internal membrane-associated protein p15 has been determined for both Rauscher and Moloney murine leukemia viruses. Peptides generated by endopeptidases and purified by HPLC were subjected to semi-automated Edman degradation. Dipeptides obtained with dipeptidyl carboxypeptidase were identified by gas chromatography-mass spectrometry. The amino acid sequence of the first 16-residue segment of Rauscher p15 is identical to the sequence of Moloney p15 except for a single amino acid substitution (Gly-->Asp) at position 13. Both proteins were found to have an acylated NH(2) terminus. By mass spectroscopy, myristic acid [CH(3)(CH(2))(12)COOH] was found to be bound through an amide linkage to the NH(2)-terminal glycyl residue in both p15s. The results of liquid chromatography show that the NH(2)-terminal myristyl group greatly contributes to the strong binding of these modified proteins and peptides to hydrophobic surfaces. Because p15 is known to be derived from the NH(2)-terminal region of a precursor polyprotein Pr65(gag) by proteolytic cleavage in the assembled virus, it is suggested that myristylation in vivo takes place during the biosynthesis of Pr65(gag). Preliminary data indicate that such modification of gag precursor polyproteins may be common to mammalian retroviruses. The role of NH(2)-terminal myristyl acylation of Pr65(gag) in virus assembly and the possibility of similar NH(2)-terminal modifications of gag-related fusion proteins of transforming viruses are discussed.

Characterization of the expression of cellular retrovirus genes and oncogenes in feline cells

Expression of endogenous retrovirus genes and two different cellular oncogenes (c-onc genes) was examined at the transcriptional level in a variety of normal and lymphoma/leukemia tissues of the domestic cat. The two oncogenes, c-myb(related to avian myeloblastosis virus) and c-myc(related to avian myelocytomatosis virus) were selected for their association with the induction of hematopoietic malignancies, when present in the transforming retroviruses. Tissue-specific expression of endogenous feline leukemia virus (FeLV)-related genes was detected in cellular subpopulations of the cat placenta by in situ method of hybridization. Gel blotting analysis of placental poly(A)-selected RNA revealed that the FeLV-related RNA species were primarily subgenomic, representing the env gene region of the endogenous provirus elements. Like the endogenous retrovirus genes, c-myb and c-myc loci of the cat genomic DNA were also transcribed at differential levels in normal tissues of the cat. Dot-blot hybridization analysis showed that the expression of these two oncogenes was linked to growth and development as it varied with the gestational age of the fetus and from fetal to adult tissues. Among the major hematopoietic organs, spleen and bone marrow contained both c-myb and c-myc transcripts, while thymus preferentially expressed the c-myb gene. In contrast to the low level of c-myc expression in fetal thymus tissues, enhanced c-myc expression was detected in all five thymomas tested and also in several other neoplasms including two granulocytic leukemias. The feline c-myb gene was not very active in granulocytic leukemias or in three of the five thymomas. RNA gel blotting analysis of poly(A)-selected RNA of a thymoma and its lymph node metastasis showed identical pattern of c-myc transcripts.

Detection and localization of a phosphotyrosine-containing onc gene product in feline tumor cells

Protein phosphorylation by a tyrosine-specific kinase is now recognized as a common event in retrovirus-transformed cells. We report in this communication that the feline sarcoma virus (FeSV) encoded transformation-specific proteins (gag-fes fusion proteins) and their associated protein kinases are also found in the FeSV in vivo induced tumor preparations, either in the form of fresh tumor homogenate or in the form of cultured cells. With the combined use of subcellular fractionation and detergent extraction we found that the protein kinase activity was present in both the membrane fraction (P100) and the cytosol (S100). The gag-fes proteins of two different strains of FeSV were found to associate with the cell framework to different degrees, suggesting that the specific conformational presentation of these proteins may be dictated by the unique portion of each polyprotein. The same gag-fes transformation related proteins could be immunoprecipitated with antiserum to phosphotyrosine.

Mouse c-myc oncogene is located on chromosome 15 and translocated to chromosome 12 in plasmacytomas

Hybridization studies with viral oncogene probes indicate that c-myc, the cellular gene homologous to the transforming gene of avian myelocytomatosis virus, resides on mouse chromosome 15 and in many plasmacytomas is translocated to the antibody heavy chain gene locus on chromosome 12. The transcriptional orientation of the translocated c-myc sequence is opposite the orientation of the adjacent C alpha gene that codes for the heavy chain of immunoglobulin A. The translocated c-myc sequence is not the same oncogene detected in urine plasmacytomas by the NIH-3T3 cell transformation assay.

Human gene (c-fes) related to the onc sequences of Snyder-Theilen feline sarcoma virus

The onc gene (v-fes) of the acutely transforming feline sarcoma virus (Snyder-Theilen strain) has homologous cellular sequences (c-fes) in all vertebrate species, including humans. We isolated from a human DNA library recombinant phages containing overlapping c-fes sequences. The human c-fes locus spans a region of 3.4 kilobases and contains 1.4 kilobases of DNA homologous to the viral onc sequence interspersed with three intervening sequences.

Nucleotide sequence of Fujinami sarcoma virus: evolutionary relationship of its transforming gene with transforming genes of other sarcoma viruses

We determined the entire nucleotide sequence of the molecularly cloned DNA of Fujinami sarcoma virus (FSV). The sequence of 1182 amino acids was deduced for the FSV transforming protein P130, the product of the FSV gag-fps fused gene. The P130 sequence was highly homologous to the amino acid sequence obtained for the gag-fes protein of feline sarcoma virus, supporting the view that fps and fes were derived from a cognate cellular gene in avian and mammalian species. In addition, FSV P130 and p60src of Rous sarcoma virus were 40% homologous in the region of the carboxyterminal 280 amino acids, which includes the phosphoacceptor tyrosine residue. These results strongly suggest that the 3' region of fps/fes and src originated from a common progenitor sequence. A portion (the U3 region) of the long terminal repeat of FSV DNA appears to be unusual among avian retroviruses in its close similarity in sequence and overall organization to the same region of the endogenous viral ev1 DNA.

Nucleotide sequences of feline retroviral oncogenes (v-fes) provide evidence for a family of tyrosine-specific protein kinase genes

The nucleotide sequences encoding the transforming polyproteins of the Snyder-Theilen and Gardner-Arnstein strains of feline sarcoma virus (FeSV) have been determined. These sequences include a viral transforming gene (v-fes), derived from cellular proto-oncogene sequences (c-fes) of domestic cats by recombination with feline leukemia virus (FeLV). The v-fes sequences are predicted to encode a polypeptide domain strikingly similar to that specified by the transforming gene (v-fps) of the avian Fujinami sarcoma virus. In addition, the 3' 0.8 kilobase pairs of v-fes encode amino acid sequences homologous to the carboxy-terminal portion of pp60src, the transforming protein encoded by the avian Rous sarcoma virus src gene. Thus different feline and avian retroviral transforming genes, all of which encode functionally related proteins with associated tyrosine-specific kinase activities, must be derived from divergent members of the same proto-oncogene family.

Human gene (c-fes) related to the onc sequences of Snyder-Theilen feline sarcoma virus

The onc gene (v-fes) of the acutely transforming feline sarcoma virus (Snyder-Theilen strain) has homologous cellular sequences (c-fes) in all vertebrate species, including humans. We isolated from a human DNA library recombinant phages containing overlapping c-fes sequences. The human c-fes locus spans a region of 3.4 kilobases and contains 1.4 kilobases of DNA homologous to the viral onc sequence interspersed with three intervening sequences.

Isolation of 16L virus: a rapidly transforming sarcoma virus from an avian leukosis virus-induced sarcoma

We have isolated a replication-defective rapidly transforming sarcoma virus (designated 16L virus) from a fibro-sarcoma in a chicken infected with td107A, a transformation-defective deletion mutant of subgroup A Schmidt-Ruppin Rous sarcoma virus. 16L virus transforms fibroblasts and causes sarcomas in infected chickens within 2 wk. Its genomic RNA is 6.0 kilobases and contains sequences homologous to the transforming gene (fps) of Fujinami sarcoma virus (FSV). RNase T1 oligonucleotide analysis shows that the 5' and 3' terminal sequences of 16L virus are indistinguishable from (and presumably derived from) td107A RNA. The central part of 16L viral RNA consists of fps-related sequences. These oligonucleotides fall into four classes: (i) oligonucleotides common to the putative transforming regions of FSV and another fps-containing avian sarcoma virus, UR1; (ii) an oligonucleotide also present in FSV but not in UR1; (iii) an oligonucleotide also present in UR1 but not in FSV; and (iv) an oligonucleotide not present in either FSV, UR1, or td107A. Cells infected with 16L virus synthesize a protein of Mr 142,000 that is immunoprecipitated with anti-gag antiserum. This protein has protein kinase activity. These results suggest that 16L virus arose by recombination between td107A and the cellular fps gene.

T24 human bladder carcinoma oncogene is an activated form of the normal human homologue of BALB- and Harvey-MSV transforming genes

A transforming gene isolated from T24 human bladder carcinoma cells is closely related to the BALB murine sarcoma virus (MSV) onc gene (v-bas). This transforming gene is localized to a 4.6 kilobase pair (kbp) region and is expressed as a 1.2-kbp polyadenylated transcript, which contains v-bas related sequences. Moreover, antisera known to detect the immunologically related onc gene products of BALB- and Harvey-MSVs recognized elevated levels of a related protein in T24 cells. The normal human homologue of v-bas was found to be indistinguishable from the T24 oncogene by heteroduplex and restriction enzyme analysis. These results imply that rather subtle genetic alterations have led to the activation of the normal human homologue of v-bas as a human transforming gene.

Human EJ bladder carcinoma oncogene is homologue of Harvey sarcoma virus ras gene

Examination of homologies between retroviral oncogenes and transforming sequences defined by transfection reveals that the human bladder carcinoma (EJ) oncogene is homologous to the Harvey sarcoma virus oncogene (ras). Structural analysis limits the region of homology to a 3.0-kilobase SacI fragment of the EJ oncogene. Both EJ and ras DNA probes detect similar transcripts in transfectants derived from bladder carcinoma cell lines.