Structure of the Ki-ras gene of the human lung carcinoma cell line Calu-1

The homologue of the viral Kirsten ras (v-Ki-ras) gene found in the human lung carcinoma cell line, Calu-1, has an intron-exon structure similar to that of the human homologue of the viral Harvey ras (v-Ha-ras) gene. A second, potential fourth coding exon is present in the human Ki-ras gene and similar sequences are found in the Kirsten murine sarcoma virus. Cysteine is encoded at the twelfth amino acid position, suggesting that the Calu-1 Ki-ras gene has undergone a mutational activation at the same position as the human Ha-ras gene of the bladder carcinoma cell line, T24. A comparison of their predicted amino acid sequences suggests that ras proteins have a 'constant' region and a 'variable' region. Here we propose a common modular structure for ras gene products in which the variable region forms a physiologically important combining site.     

Nucleotide sequence and formation of the transforming gene of a mouse sarcoma virus

The complete nucleotide sequence of the transforming gene of a mouse sarcoma virus has been determined. It codes for a protein of 374 amino acids. The nucleotide sequence of the junctions between a murine leukaemia virus and cellular sequences leading to the formation of the viral transforming gene have also been elucidated. The viral transforming sequence and its cellular homologue share an uninterrupted stretch of 1,159 nucleotides, with few base substitutions. The predicted amino acid sequence of the mouse sarcoma virus transforming gene was found to share considerable homology with the proposed amino acid sequence of the avian sarcoma virus oncogene (src) product.     

The transforming gene of Moloney murine sarcoma virus

A cleavage map of the Moloney murine sarcoma viral DNA was constructed and compared with that of a spontaneously occurring deletion mutant. By restriction enzyme analysis, it was shown that a region encompassing over 40% of the viral information was not essential for transformation or rescue of the deletion mutant. The transforming region was further localised by analysis of the transforming activity in tissue culture of isolated restriction fragments of linear duoble-stranded sarcoma viral DNA. In each case, DNA fragments that retained transforming activity preserved the cell-derived insertion sequences of the viral genome. Moreover, such transformants invariably expressed RNA specific to this region. By these two approaches, it was possible to demonstrate that the transforming region of the viral genome begins very near or within the cell-derived insertion sequences. Thus, the transforming gene of this mammalian sarcoma virus originates from within the mouse cell genome.     

Molecular cloning of a new transforming gene from a chemically transformed human cell line

Molecular cloning of the transforming gene from a chemically transformed human osteosarcoma-derived cell line enables the gene to be mapped to chromosome 7 (7p11.4-7qter) and by this criterion and by direct hybridization to be shown to be unrelated to known oncogenes.     

Ha-ras oncogenes are activated by somatic alterations in human urinary tract tumours

DNA-mediated gene transfer (transfection) studies using NIH 3T3 cells as recipients have demonstrated the presence of transforming genes (oncogenes) in diverse human tumours. A large proportion of oncogenes so far detected by DNA transfection are related to the Ha-ras onc gene of Harvey (and BALB) murine sarcoma viruses (MSV), Ki-ras, the oncogene of Kirsten MSV, and a third member of the ras gene family, N-ras. Individual tumours of many different organs have been associated with the activation of members of the ras gene family. We now present the first systematic survey of human urinary tract tumours processed immediately after surgery, as well as normal tissues from the same patients, to detect the presence of such genes. We demonstrate activation of Ha-ras as an oncogene in around 10% of randomly selected urinary tract tumours as well as direct evidence that oncogene activation is the result of a somatic event which is selected for within the tumour cell population.     

Local degradation of fibronectin at sites of expression of the transforming gene product pp60src

Local degradation of extracellular fibronectin, a major extracellular adhesive protein, is believed to play an important part in the migration of cells through the extracellular matrix during tumour invasion, morphogenetic movement and trophoblast implantation. Fibronectin is lost from the cell surface after transformation with Rous sarcoma virus (RSV). By using fluorescent and radiolabelled probes covalently coupled to the surface of substrata, we have recently identified a proteolytic activity that is expressed in RSV-transformed cells and is involved in the local degradation of fibronectin at cell-substratum contact sites. Here, we extend the relevance of these findings and gain some insight into the cellular functions of pp60src, the transforming gene product of RSV. We show that newly expressed viral pp60src is localized at the cytoplasmic surface of the cell membrane, corresponding to the cell contact sites where degradation of extracellular fibronectin occurs.     

Avian sarcoma virus Y73 genome sequence and structural similarity of its transforming gene product to that of Rous sarcoma virus

From the complete nucleotide sequence of the genome of the avian sarcoma virus Y73, we have predicted amino acid sequence of p90 gag-yes, the product of the transforming gene. Contrary to previous evidence from molecular hybridization studies p90 gag-yes was found to have much homology with the transforming gene product p60 src of Rous sarcoma virus, suggesting that the cellular counterparts of the two (c-yes and c-src) originated from a common prototype sequence.     

Reciprocal chromosome translocation between c-myc and immunoglobulin gamma 2b genes

Specific chromosome translocations have been observed in transformed cell lines of both man and mouse and may be implicated in the origin or maintenance of malignancy. In mouse plasmacytomas, translocations have been identified that bring the immunoglobulin alpha heavy-chain gene (C alpha, normally located on chromosome 12) into proximity with c-myc (normally located on chromosome 15), c-myc being the mouse cellular homologue of the avian myelocytomatosis virus transforming gene (v-myc). Here we identify a DNA rearrangement in a mouse hybridoma that has brought c-myc close to C gamma 2b and show that this rearrangement occurred by reciprocal chromosome translocation, as recombinant clones were isolated from the same cell line in which a rearranged variable-region (VH) gene has been brought close to 5' c-myc sequences. The translocation has resulted in the net loss of 7 base pairs (bp) of chromosome 15 sequence as well as in the presence of an additional base of unknown provenance. This reciprocal translocation was analysed in DNA from a mouse hybridoma cell line but is shown to be characteristic of the X63Ag8 myeloma parent.     

Molecular cloning and nucleotide sequence of a transforming gene detected by transfection of chicken B-cell lymphoma DNA

A transforming gene detected by transfection of chicken B-cell lymphoma DNA has been isolated by molecular cloning. It is homologous to a conserved family of sequences present in normal chicken and human DNAs but is not related to transforming genes of acutely transforming retroviruses. The nucleotide sequence of the cloned transforming gene suggests that it encodes a protein that is partially homologous to the amino terminus of transferrin and related proteins although only about one tenth the size of transferrin.     

Activation of Ki-ras2 gene in human colon and lung carcinomas by two different point mutations

Kirsten (Ki)-ras cDNA clones were prepared from human lung and colon carcinoma cell lines expressing an activated c-Ki-ras2 gene. DNA sequence analysis and transfection studies indicate that different point mutations at the same codon can activate the gene; that most human c-Ki-ras2 mRNA uses sequences from a fourth coding exon distinct from that of its viral counterpart; and that at least one cell line is functionally homozygous for the activated gene.     

人肿瘤细胞株中细小病毒H—1的DNA扩增与非结构蛋白NS—1基因的表达

研究三株人癌细胞和两株对照细胞对细小病毒Ｈ－１杀伤作用敏感性的分子机制．表明了在感染复数ｍｏｉ（ｍｕｌｔｉｐｉｃｉｔｙｏｆｉｎｆｅｃｔｉｏｎ）为５ｐｆｕ（ｐｌａｑｕｅｆｏｒｍｉｎｇｕｎｉｔ）／细胞的情况下，作为Ｈ—１病毒复制受纳细胞的人肝癌细胞株ＯＧＹ－７７０３和人胃癌细胞株ＳＧＣ—７９０１，能够支持病毒ＤＮＡ扩增和非结构蛋白ＮＳ—１基因的表达，这和作为阳性对照的由ＳＶ４０转化的新生儿肾细胞株ＮＢ—Ｋ一样，但对Ｈ—１病毒感染有抗性的人肾癌细胞株ＯＵＲ—１０和它的对照人胎肾细胞株ＨｕＫ—１，并不支持病毒ＤＮＡ扩增和ＮＳ—１蛋白的表达．本文结果指出，细小病毒Ｈ—１的杀伤作用与细胞中的病毒ＤＮＡ扩增及ＮＳ—１基因表达的程度相关．     

Evidence for two distinct c-src loci on human chromosomes 1 and 20

A number of proto-oncogenes have recently been localized to the chromosomal segments that are the breakpoints in the specific rearrangements noted in human malignant diseases. Moreover, rearranged forms of several proto-oncogenes have been identified in malignant cells; in several instances, the proto-oncogene has undergone an alteration as a result of a nonrandom chromosomal rearrangement. One proto-oncogene that has yet to be associated with human neoplastic disease is c-src, the cellular homologue of the transforming sequence of Rous sarcoma virus (RSV). By somatic cell hybridization, c-src has been mapped to chromosome 20, but its precise location was not determined. We have now mapped this gene by using in situ hybridization of the cloned human c-src probe to human mitotic chromosomes. We report here that the human genome contains two loci with strong homology to the coding regions of this oncogene, at 1p34-p36 and 20q12-q13. It is noteworthy that these chromosomal regions are frequently involved in the structural rearrangements observed in haematological malignant diseases.     

A yeast gene encoding a protein homologous to the human c-has/bas proto-oncogene product

Organisms amenable to easy genetic analysis should prove helpful in assessing the function of at least those proto-oncogene products which are highly conserved in different eukaryotic cells. One obvious possibility is to pursue the matter in Drosophila melanogaster DNA, which has sequences homologous to several vertebrate oncogenes. Another is to turn to the yeast Saccharomyces cerevisiae, if it contains proto-oncogene sequences. Here we report the identification of a gene in S. cerevisiae which codes for a 206 amino acid protein (YP2) that exhibits striking homology to the p21 products of the human c-has/bas proto-oncogenes and the transforming p21 proteins of the Harvey (v-rasH) and Kirsten (v-rasK) murine sarcoma viral oncogenes. The YP2 gene is located between the actin and the tubulin gene on chromosome VI and is expressed in growing cells. The protein it encodes might share the nucleotide-binding capacity of p21 proteins.     

Structural and immunological similarities between simian sarcoma virus gene product(s) and human platelet-derived growth factor

The predicted amino acid sequence of the simian sarcoma virus (SSV) transforming gene product, p28sis, closely corresponds to that of human platelet-derived growth factor (PDGF). We demonstrate that p28sis rapidly undergoes a series of discrete processing steps including dimer formation and proteolytic digestion to yield molecules structurally and immunologically resembling biologically active PDGF.     

Platelet-derived growth factor is structurally related to the putative transforming protein p28sis of simian sarcoma virus

A partial amino acid sequence of human platelet-derived growth factor, the major mitogen in serum for cells of mesenchymal origin, has been determined. A region of 104 contiguous amino acids shows virtual identity with the predicted sequence of p28sis, the putative transforming protein of simian sarcoma virus (SSV). This similarity suggests a mechanism for transformation by SSV and other agents, involving expression of growth factors.     

Structural alteration of viral homologue of receptor proto-oncogene fms at carboxyl terminus

A role for proto-oncogenes in the regulation and modulation of cell proliferation has been suggested by the findings that the B-chain of platelet-derived growth factor (PDGF) is encoded by the proto-oncogene sis and that the erb-B oncogene product is a truncated form of the epidermal growth factor (EGF) receptor. Furthermore, the product of the proto-oncogene fms (c-fms) may be related or identical to the receptor for macrophage colony-stimulating factor (CSF-1). v-fms is the transforming gene of the McDonough strain of feline sarcoma virus (SM-FeSV) and belongs to the family of src-related oncogenes which have tyrosine-specific kinase activity. Furthermore, nucleotide sequence analysis of the v-fms gene product revealed topological properties of a cell-surface receptor protein. To elucidate the features involved in the conversion of a normal cell-surface receptor gene into an oncogenic one, we have now determined the complete nucleotide sequence of a human c-fms complementary DNA. The 972-amino-acid c-fms protein has an extracellular domain, a membrane-spanning region, and a cytoplasmic tyrosine protein kinase domain. Comparison of the feline v-fms and human c-fms sequences reveals that the proteins share extensive homology but have different carboxyl termini.