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P N Liu

Publications and source records attributed to P N Liu.

7 recordsLinked to original sources
PubMed1991

Anti-FD4 idiotypic antibody mimicking human gastric cancer-associated antigen.

Rabbits were immunized with the Fab fragment of a murine monoclonal antibody (McAb) PD4 against human gastric cancer to produce anti-PD4-idiotypic antibody (alpha PD4-Ab2). The alpha PD4-Ab2 could not only competitively inhibit binding of McAb PD4 to gastric cancer cell MGC803, but also induce delayed-type hypersensitivity (DTH) to MGC803 in mice. Spleen cells of mice immunized with alpha PD4-Ab2 were fused with myeloma cell SP2/0 to form hybridoma secreting Ab3 which could be bound to target cell MGC803. McAb C7-Ab3, one of the Ab3, could selectively react with a 40 kD tumor-associated antigen located on MGC803 cell membrane, as well as McAb PD4. The results indicate that alpha PD4-Ab2 possesses determinants (internal image antigen) similar to those on MGC803, and could mimic human gastric cancer-associated antigen.

Animals↗
PubMed1987

Activated c-Ha-ras oncogene with a guanine to thymine transversion at the twelfth codon in a human stomach cancer cell line.

The rat fibroblast cell line Rat 1 was transfected with total DNA of a gastrocarcinoma cell line, BGC-823. The transforming gene was cloned from the genomic library of the secondary transformants using in situ hybridization with a probe of the human Alu repeat sequence. This cloned gene is homologous to the protooncogene c-Ha-ras. The activation lesion of the transforming gene was identified by sequence analysis as a single nucleotide substitution of thymine for guanine in the 12th codon. This results in the substitution of valine for glycine at the 12th amino acid of the Mr 21,000 protein.

Adenocarcinoma↗
PubMed1987

Molecular cloning and nucleotide sequence analysis of a transforming gene from human gastrocarcinoma cell line.

Mouse and rat fibroblasts were transfected with total DNA from human gastrocarcinoma cell line BGC-823. It was shown by hybridization assay that the genome of one of the rat secondary foci contains transforming genes from the human gastrocarcinoma cell line, which are homologous to the protooncogene c-Ha-ras in the normal cells. The genomic library of the rat secondary foci was constructed, using lambda phage EMBL3 as the vector. The transforming gene Ha-ras of the human gastrocarcinoma cell was thus cloned by screening the library with the probes of human Alu repeat sequence and c-Ha-ras. The nucleotide sequences of the first and second exons were analysed by M13-dideoxy method. The result shows that the nucleotide sequence of the transforming gene is the same as that of the normal protooncogene except one nucleotide difference in the first exon.

Amino Acid Sequence↗
PubMed1986

[DNA transformation activity of a human gastrocarcinoma cell line].

DNAs of three cell lines of human gastrocarcinoma (MGC-803, BGC-823 and PACM-82) and two fresh solid tumors of human stomach cancer were used to transfect NIH3T3 and Rat-1 cells. The transformed cells were selected with high concentration of glucose and low concentration of serum, or with medium containing Geneticin (G418) after co-transfection of pSVneo and DNAs of stomach cancer cell line or primary transformants. From the second round transfection, we had obtained transformants which could grow with high colony forming efficiency in soft agarose and were tumorigenic in nude mice. The southern blot analysis showed that the cellular DNA of the transformants contained human Alu repeat sequence and the transformed gene from stomach cancer cell line (BGC-823) and was homologous to proto-oncogene c-Ha-ras. The transforming gene is able to induce neoplastic transformation of NIH3T3 and Rat-1 cells.

Animals↗