[Protein composition and electron microscopy of the residual protein fractions of cell nuclei of certain normal organs and tumors of rats]

A marked difference in polypeptide pattern and electron micrographs of the nuclear residual protein fraction between normal tissues /liver, kidney, spleen/ and tumors /hepatoma 27, Jensen and Yoshida sarcomas/ is revealed. While in normal tissues the polypeptides with molecular weight lower than 26 KD constituted about one half of the total residual protein, in tumors the polypeptides with molecular weight exceeding 100 KD were markedly prevailing. In electron micrographs the uniform filaments with a diameter of 4-5 nm, and periodical structure represented the bulk of the preparation from normal liver, while in the case of hepatoma 27 an amorphous granulated material was predominating.

Tumoral myosins of Ni3S2-induced rhabdomyosarcomas in rat and rabbit: comparative studies with adult and fetal myosins of skeletal muscle

Tumoral myosins were isolated from rat and rabbit rhabdomyosarcomas and compared with normal adult and fetal skeletal myosins. The synthetic filaments, the light-chain composition and the Ca2+ ATP-ase activity were studied. In the presence of Mg2+, normal myosins precipitated as bipolar filaments (0.5 micrometer), fetal and tumoral myosins, however, precipitated as long fusiform filaments (1 to 10 micron). SDS-PAGE revealed that tumoral myosins contain the same light-chains as fetal myosin (25000 and 18000 daltons, L25-L18). The third light-chain of the normal muscle myosin (16000 daltons, L16) was absent. In addition, Urea-PAGE revealed the absence of the phosphorylated form of the L18 in fetal and tumoral myosins. Ca2+ ATPase activity measurements performed in function of the Ca2+ concentration showed similarities between fetal and adult muscle myosins. The Ca2+-ATPase activity of tumoral myosins, however, was very low and slightly activated by increasing the Ca2+ concentration (0.01 to 10 mM). The investigation has shown that fetal and tumoral myosins are identical concerning the ultrastructure of their synthetic filaments and their light-chain composition. This was not so in regard to the Ca2+ ATPase activity. This is probably the result of the expression of a new myosin- or of one of its polypeptides-, which has a different Ca2+-ATPase activity.

Laminin--a glycoprotein from basement membranes

We have isolated a large noncollagenous glycoprotein, laminin, from a mouse tumor that produces basement membrane. The protein consists of at least two polypeptide chains (Mr = 220,000 and Mr = 440,000) joined to each other by disulfide bonds. Laminin and type IV collagen are major constituents of the tumor. Laminin is distinctly different from fibronectin, another component of basement membranes, in amino acid composition and immunological reactivity. Pepsin digestion of laminin releases a large, cystine-rich fragment which retains most of the antigenicity of the original protein. Immunological studies using purified antibody against laminin show that it is produced by a variety of cultured cells. In addition, these antibodies react with the basement membranes of normal tissues, suggesting that this protein or an immunologically related protein is a constituent of the basement membranes of these tissues.

[Polyamine content in tissues of 7,12-dimethyl-benz(a)anthracene-induced sarcoma and liver of tumor-carrying rats]

Putrescine in determinable amounts is contained in the tumour tissue, in the liver tissue of normal animals it was not detected by the applied method. The spermidine content in the tumour is also considerably higher, it is 15.-3 times as high as that in the normal liver both per 1 g of fresh tissue and per 1 mg of RNA. The spermine content in the tumours is somewhat lower as compared to its content in the normal liver. The shifts in the contents of polyamines are of the same character both for the liver of rats with carcinogen-induced sarcomas and for tumours. Putrescine is determined in noticeable amounts in the liver of tumour-carrying rats. Thus, the carcinoven-induced sarcoma as well as the liver of rats with sarcomas are characterized by a high content of putrescine and spermidine as well as by a high value of the spermidine/spermine ratio.

Identification of a Rous sarcoma virus transformation-related protein in normal avian and mammalian cells

Avian sarcoma viruses (ASV) contain a gene (src) whose protein product mediates sarcomagenic transformation. This product is a 60,000-Mr phosphoprotein designated pp60src. We have found that normal uninfected frog, chicken, rat, and human cells contain a 60,000-Mr phosphoprotein related to the product of the ASV src gene and have designated that protein pp60. A phosphoprotein of similar size was not detectable in Drosophila cells. The pp60 proteins were detected by immunoprecipitation with rabbit antitumor serum containing broad spectrum antibodies to pp60src. Peptide maps of [35S]methionine-labeled pp60 and pp60src indicated major similarities as well as some differences in amino acid composition. Peptide maps of the 32P-labeled proteins demonstrated that the phosphopeptides of all endogenous pp60 molecules tested were identical. However, some differences were noted between the phosphopeptide patterns of pp60 and viral pp60src. The kinase activity associated with pp60src was measured in the immunocomplex and resulted in the transfer of radioactive phosphorus from [gamma-32P]ATP to the immunoglobulin heavy chain as well as to an 80,000-Mr phosphoprotein. The pp60 of chicken, rat, and human origin also contained an associated kinase activity. These results are consistent with the notion that the pp60 molecules are the protein products of endogenous sarc sequences found in vertebrate cells.

Leukotriene C: a slow-reacting substance from murine mastocytoma cells

Murine mastocytoma cells treated with calcium ionophore A23187 produced a slow-reacting substance (SRS) that caused guinea pig ileum to contract. The response was reversed by the SRS antagonist FPL 55712. On the basis of isotope incorporation experiments, spectroscopy, and chemical degradations, the SRS was identified as a cysteine-containing derivative of 5-hydroxy-7,9,11,14-icosatetraenoic acid. This amino acid was attached in thioether linkage at C-6. The SRS is structurally related to previously identified epoxy and dihydroxy metabolites of arachidonic acid in leukocytes. A common feature is the presence of a conjugated triene, and the name "leukotriene" has been introduced to designate these compounds. Leukotriene A (5,6-epoxy-7,9,11,14-icosatetraenoic acid) is an intermediate in the formation of leukotriene B (5,12-dihydroxy-6,8,10,14-icosatetraenoic acid) and is proposed to be a precursor also of leukotriene C, which is the SRS identified here.

Transition metals in an experimental tumour system

In this report we present an analysis by atomic absorption spectrometry of some of the transition metals Fe, Zn, Cu, Mn, Co, and Ni in tissues and nuclear fractions in an experimental tumour system.

Fractionation and characterization of euchromatin isolated from mouse ascites sarcoma cells

Euchromatin specimen prepared by the usual method formed large clumps and had various shapes under electron microscopy. A method of separation of the euchromatin specimen into chromatin fractions having relatively homogeneous form was examined and partial characterization of these fractions was carried out. The heavy euchromatin fraction was a large network of thin fibrils (about 100 A in diameter) and various thick fibers. The intermediate euchromatin fraction consisted of relatively homogeneous networks of thick knobby fibers (about 250 A in diameter). The light euchromatin fraction had metworks of thick fibers. These chromatin fractions were quantitatively prepared from sonicated nuclei of mouse ascites sarcoma cells. Twenty-one or twenty-two bands of non-histone proteins besides histones were detected in these chromatin fractions by SDS-polyacrylamide gel electrophoresis. There were significant differences in the electrophoretic patterns of non-histone proteins among these chromatin fractions.

Comparison of polypeptides from cultured human fibroblasts and sarcoma cells

The proteins in cell layers of cultured normal diploid human skin (ES, ER) and lung (WI-38) fibroblasts were compared to those of SV40-transformed human fibroblasts (WI-38/VA-13), human rhabdomyosarcoma (RD) and fibrosarcoma (HT-1080) cells using metabolic amino acid and sugar labeling and surface labeling with tritiated sodium borohydride after oxidation with galactose oxidase. The labeled proteins were analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography (fluorography). A transformation-associated decrease in the pericellular glycoprotein fibronectin (subunit molecular weight, 220 000) and in the synthesis of a set of polypeptides in the 130 000--180 000 dalton region was seen. Synthesis of a glycosylated 160 000 dalton polypeptide was markedly reduced. In transformed cells distinct increases of several specific polypeptides was detected in both [35S]methionine and [3H] mannose incorporation experiments but not using the surface labeling method.

Isolation from a murine fibrosarcoma of cell lines with enhanced plating efficiency in vitro

The technique for the isolation of mutants was applied to establish highly clonogenic cells from a fibrosarcoma (FSA) that had an extremely poor growth capacity in vitro (10(-6)--10(-7) of surviving fraction of cells). After consecutive clonings, the surviving fraction of cells increased to 1--5 X 10(-1), whereas that of the ordinarily maintained culture remained at a low level. Selected clones were analyzed in vitro and/or in vivo. The results indicated that the FSA was composed of heterogeneous cells or cells having a potential variability in cloning ability in vitro, metastatic ability in vivo [lung colony-forming efficiency (LCFE)], and DNA content. The relatively high DNA content of one of the clones, FSA 1233, continued after growth in vivo or in vitro, indicating its hereditary nature. FSA 1233 was also demonstrated to have a lower LCFE when the cell suspension was made from a tumor rather than from a culture in vitro. The difference of surviving fractions between the cells in the two conditions was not enough to explain the difference in LCFE's between them. These cells could grow under either in vitro or in vivo conditions and could be made readily into single-cell suspensions. The cells are, therefore, available as a system for analysis of the response of cells in vitro after in vivo treatment with various agents.

Recovery of avian sarcoma virus from tumors induced by transformation-defective mutants

Transformation-defective (td) mutants of the Schmidt-Ruppin strain of Rous sarcoma virus (RSV), which contains deletions in the gene responsible for transformation (src gene), are unable to transform chicken embryo fibroblasts in vitro. Injection of some of these td mutants into newborn chickens resulted in the formation of sarcomas from which sarcoma virus was unfailingly recovered. The possibility that transforming RSV was present in the td virus preparations was excluded by further purification of the td viruses. Morphology of the foci induced by the newly recovered sarcoma virus was distinct from that of foci induced by the parental Schmidt Ruppin strain of RSV. It is suggested that the new sarcoma virus was generated as a result of the genetic interaction between the genomes of td virus and chicken cells.

Dual-frequency proton spin relaxation measurements on tissues form normal and tumor-bearing mice

Measurements of pulsed nuclear magnetic resonance relaxation times T1 and T2 were made at 2.7 MHz and 15 MHz on water protons in liver, kidney, spleen, muscle, and brain tissue from normal A.SW mice, and in the same tissues and tumors from A.SW mice developing MSWBS tumors (an ascites sarcoma) following dorsal sc implantation of tumor fragments. The measurement precision obtained from improved spectrometer design made it possible to show that T1 and T2 in all tissues except brain were increased by the presence of the tumor in the animal. The responses exhibited by T1 and T2 in liver and kidney were proportional to the size of the tumor. The smaller responses shown by T1 in spleen (15 MHz) and T1 and T2 in muscle (2.7 MHz) also showed a significant correlation with tumor size. The relaxation times for tumor (T1 at 2.7 MHz, T2 at 2.7 and 15 MHz) showed a significant negative correlation with tumor size: The times decreased as tumor size increased. The results were analyzed by use of the two-phase fast exchange model and were consistent with the effects expected if tissue water content increased and tumor water content decreased as tumor size increased. The analysis indicated that the effects arose primarily through changes in b, the fraction of water bound to fast exchange sites on the protein, with important modifications from changes in the correlation times Tc and Tm;Tr controlled the frequency that must be chosen for specific diagnostic applications.