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N Tsuchida

Publications and source records attributed to N Tsuchida.

104 records · Page 6Linked to original sources
PubMed1974

Mutants of nonproducer cell lines transformed by murine sarcoma virus. 3. Detection and characterization of RNA specific for helper and sarcoma viruses.

BALB/3T3 cells transformed by the Kirsten sarcoma virus (nonvirus producer BALB/3T3 cells) and mutant cell lines derived therefrom by treatment with bromodeoxyuridine (BrdU) were analyzed for expression of virus-specific RNA using single-stranded DNA transcripts of Rauscher leukemia virus (RLV), a virus activated in one of the cell lines (58-2T), and Ki-SV-specific DNA transcript; the latter transcript after removal of all sequences cross-reactive with RLV RNA. The Rauscher virus DNA detected multiple copies of viral RNA in virus-producing cells ( approximately 2.5 x 10(3)/cell) whether infected with RLV or activated to produce virus with BrdU. Nonproducer (NP) cells and normal BALB cells showed small numbers of RNA genomes (70-250/cell) and only partial saturation of the transcript. The intracellular RNA sedimented at 35S (main peak) with a variable minor peak at 20S with the exception of one mutant cell, M-43-2 (main peak at 26-27S). The 58-2T transcript reacted preferentially in NP cells and their derivatives with biphasic kinetics suggesting the possibility of sequences specific for the original transforming virus. The size of Ki-SV specific sequences were 30S in mutant cells whether or not complete virus was being produced and independent of in vivo transplantability.

Animals↗
PubMed1974

Sarcoma-virus-related RNA sequences in normal rat cells.

A rat type C virus spontaneously activated from the NRK (normal rat kidney) cell line was found to have two major size classes of viral RNA subunits sedimenting at 35 and 30 S. Virus-producing cells contained both RNA species, while normal "virus-free" rat cells contained primarily virus-specific 30S RNA species. A DNA transcript, specific for Kirsten sarcoma virus, prepared from virus activated in nonproducer BALB/c cells originally transformed by Kirsten sarcoma virus and rendered specific for the virus by absorption of sequences related to mouse helper virus hybridized only with the 30S RNA species of virus-producing rat cells and normal rat cells. These findings are consistent with the hypothesis that sarcoma-specific nucleic acid sequences in kirsten sarcoma virus emerged through a process that incorporated some portions of 30S RNA species from rat cells (either normal or virus-producing) into the Kirsten leukemia virus during passage in vivo of that virus. The virus designated M-MSV(RaLV), which originally derived from tumor induced by Moloney sarcoma virus (M-MSV) in rats, contained 35S RNA species of rat type C viruses and 30S RNA species specific for both rat and mouse viruses. It appears striking that for these two animal species, sarcoma-virus-specific information resides on a 30S subunit.

Animals↗
PubMed1974

Intracellular viral RNA species in mouse cells nonproductively transformed by the murine sarcoma virus.

The size and quantity of virus-specific RNA in five non-virus-producing mouse cells transformed by the Moloney isolate of murine sarcoma virus (MSV) was determined. Hybridization of RNA from transformed cells with the [(3)H]DNA product of the RNA-directed DNA polymerase of the murine sarcoma-leukemia virus was used to detect and quantitate virus-specific RNA. The amount of virus-specific RNA in non-virus-producing cells was less than one-sixth of that found in virus-producing cells. A striking correlation was found between the amount of intracellular virus-specific RNA and the degree of agglutination by conconavalin A previously reported for the four non-virus-producing NIH/3T3 cell lines (Salzberg and Green, 1974). A major RNA subunit sedimenting at 26 to 28S was detected in all five MSV-transformed non-virus-producing cells. This could represent the RNA genome of defective MSV.

Animals↗
PubMed1974

Sarcoma and helper-specific RNA tumor virus subunits in transformed nonproducer mouse cells activated to produce virus by treatment with bromodeoxyuridine.

A tumor line (58-2T) was established from a slowly growing tumor in a BALB/c mouse inoculated with M58-2 cells. The latter clonal cell line was isolated after bromodeoxyuridine treatment as a flat variant from nonproducer BALB/3T3 cells transformed by the Kirsten sarcoma virus. The 58-2T cells produced type C virus with two discrete virus-specific RNA species. One of the species, which was probably an endogenous virus RNA subunit, had a sedimentation coefficient of 35S as the largest major subunit, and had sequences similar to Rauscher leukemia virus RNA based on nucleic acid hybridization. The other RNA species had 30S as the largest major subunit and corresponded to Kirsten sarcoma virus-specific RNA. These two RNA species formed heterogeneous, 60 to 70S, high-molecular-weight RNA in virions.DNA transcripts (58-2T DNA) from the activated virus contained base sequences complementary to Rauscher leukemia virus and Kirsten sarcoma virus. The Kirsten sarcoma virus-specific DNA sequences (58-2TS) were purified from 58-2T DNA by eliminating RLV-specific sequences.

Animals↗
PubMed1973

Virus-specific messenger RNA and nascent polypeptides in polyribosomes of cells replicating murine sarcoma-leukemia viruses.

We present evidence that virus-specific RNA is present in polyribosomes of transformed cells replicating the murine sarcoma-leukemia virus complex and that it serves as messenger RNA for the synthesis of viral-coded proteins. Both virus-specific RNA (detected by hybridization with the [(3)H]DNA product of the viral RNA-directed DNA polymerase) and nascent viral polypeptides (measured by precipitation with antiserum to purified virus) were found in membrane-bound and free polyribosomes. Membrane-bound polyribosomes contained a higher content of both virus-specific RNA and nascent viral polypeptides. From 60 to 70% of viral RNA sequences were released from polyribosomes with EDTA, consistent with a function as messenger RNA. Maximum amounts of both virus-specific RNA and nascent viral polypeptides were found in the polyribosome region sedimenting at about 350 S.

Animals↗
PubMed1972

Viral RNA subunits in cells transformed by RNA tumor viruses.

Single-stranded 35S and 20S viral RNA species are synthesized in virus-producing mouse and rat cells transformed by the murine sarcoma virus. A transformed hamster cell line that does not produce virus synthesizes 35S, but not 20S viral RNA.

Animals↗
PubMedDate not supplied

Gene amplification and overexpression of epidermal growth factor receptor in squamous cell carcinoma of the head and neck.

The degree of gene amplification for epidermal growth factor receptor (EGFR) and its expression levels were examined in 4 cases of tumor lesions and their cell lines of human squamous cell carcinoma (SCC) of the oral cavity. The amplification was detected in 1 case (ZA), but not significantly in 3 other cases (HOC605, HOC815, and HOC927) in which the amplification did not occur during the cell line establishment. In those 3 cases, levels of EGFR synthesis and human EGF (hEGF) binding capacity were varied: HOC605 and HOC815 had slightly increased levels of hEGF binding capacity and EGFR synthesis, respectively. While HOC927 had the lowest levels of both, the hEGF binding capacity was elevated in the tumor lesion when compared with the normal counterpart of the same patient. These results suggest that the increased capacity for EGF binding plays a more important role than does gene amplification on the tumorigenesis of SCC of the head and neck.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Upregulation of non-mutated H-ras and its upstream and downstream signaling proteins in colorectal cancer.

We analyzed H-ras protein expression in 38 human colon cancers and the paired normal tissues. H-ras levels were significantly higher in the malignant tumor (average 0.19+/-0.27) than in its normal adjacent tissues (average 0.06+/-0.15) (p<0.05). The H-ras protein expressed in colon carcinomas contained activated form of H-ras without mutation, based on the findings obtained by RBD-binding (ras binding domain of Raf protein) assay and PCR-SSCP analysis. In addition, we found that H-ras expression was higher in female patients than male, and in cancers with distant metastasis compared to those with non-distant metastasis. Good correlation between H-ras expression levels and those of the upstream and downstream signaling proteins of EGFR, MEK and ERK was found, suggesting that H-ras may play a significant role in carcinogenesis of colorectal cancer.

Aged↗