Biomedical subjects

S Gamou

Publications and source records attributed to S Gamou.

41 records · Page 3Linked to original sources

PubMed1985

Giant cell carcinomas of the lung producing colony-stimulating factor in vitro and in vivo.

Two culture cell lines (C-Lu65, C-Lu99) were established from human giant cell carcinomas of the lung transplanted in athymic nude mice (BALB/c, nu/nu). During early passage in tissue culture, C-Lu65 grew as a loosely adherent monolayer with some piling-up and with floating cells. After 30 successive subcultures, C-Lu65 began to grow in suspended cell clusters, showing a faster growth rate. C-Lu65 was characterized by multinucleated giant cells with large abnormal nuclei and prominent nucleoli. C-Lu99 grew as adherent cells, and fewer multinucleated giant cells were observed. C-Lu65 and C-Lu99 showed some ultrastructural differences in cell surface and cytoplasmic features. Chromosomal analysis revealed numerical and structural abnormalities in both cell lines. Cell-free supernatants from both cell lines stimulated the colony formation of mouse bone marrow cells in vitro. In addition, mice bearing tumors induced by transplanting C-Lu65 and C-Lu99 showed remarkable leukocytosis without evidence of infection. These results suggest that these two cell lines release colony-stimulating factor both in vitro and in vivo.

Animals↗

PubMed1984

Genetic analysis of hyperproduction of epidermal growth factor receptors in human epidermoid carcinoma A431 cells.

Human epidermoid carcinoma A431 cells, possessing an extraordinarily high number of epidermal growth factor (EGF) receptors (1), were found to be hypotetraploid in their chromosome constitution and to contain two copies of intact chromosome 7 and two types of the translocation chromosomes involving chromosome 7 (M4 and M14) as well as several other rearranged chromosomes. The A431 cells were fused with mouse A9 cells, which lack EGF receptors (2) and are deficient in hypoxanthine phosphoribosyltransferase (3), and the human-mouse cell hybrid (AA series) were selected in HAT/ouabain medium (3, 4). The expression of high EGF binding ability was correlated with the presence of human translocation chromosome M4. AA hybrid clones that contained intact human chromosome 7 but not the marker chromosome M4 expressed only ordinary levels of EGF receptors. The EGF receptors expressed in the AA hybrids were proven to be of human nature by immunoprecipitation of the receptors cross-linked with [125I]EGF. These observations and our previous gene assignment of the EGF receptor to human chromosome 7 (2, 5) suggest that the marker chromosome M4 may carry an alteration(s) in the gene(s) involved in EGF receptor biosynthesis.

Animals↗

PubMed1984

Different responses to EGF in two human carcinoma cell lines, A431 and UCVA-1, possessing high numbers of EGF receptors.

EGF binding capacity was examined in 9 different human cell lines which were derived from colon, rectum and pancreas tumors. Among these cell lines, a pancreatic carcinoma cell line, UCVA-1, was found to possess a high number (0.9 X 10(6)/cell) of EGF receptors. This number is comparable to that of EGF receptors in human vulva epidermoid carcinoma A431 cells (2 X 10(6)/cell). However, it was found that, unlike A431 cells, the growth of UCVA-1 cells, in serum-containing and serum-free conditions, was not inhibited by EGF. The UCVA-1 cells have EGF receptor of Mr = 170 K and of two affinity types: Kd1 = 72 X 10(-9) M and Kd2 = 2 X 10(-8) M. The EGF receptors in UCVA-1 cells are less susceptible to proteolytic cleavage than those in A431 cells. In UCVA-1 cells, EGF is apparently processed via a receptor-mediated endocytosis. The UCVA-1 cell membrane contained EGF-stimulated protein kinase as was found in A431 cells. The stimulation of phosphorylation by EGF was only approximately 20% in UCVA-1 while it was over 100% in A431. When angiotensin II was used as a substrate, the relative activity of EGF-dependent tyrosine-specific protein phosphorylation was approximately 8 times less in UCVA-1 cell membrane. The EGF-stimulated phosphorylation was mostly on EGF receptors for both cell lines. However, several other components (Mr = 100 K, 80 K, 72 K and 65 K) were readily detected in A431 cells. These observations indicate that the EGF receptor/protein kinase relation differs in these two cell lines and suggests that it may be related to the growth-inhibitory effect of EGF seen in A431.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Immunogene approach toward cancer therapy using erythrocyte growth factor receptor-mediated gene delivery.

In this article we describe an improved method to produce a conjugate of anti-erythrocyte growth factor (EGF) receptor monoclonal antibody with polylysine via thio-ether bonds. The resulting antibody/polylysine conjugate was found to be a much more stable DNA (gene) carrier than the previous conjugate formed via disulfide bonds. We designated the conjugate as an "immunoporter" and the immunoporter/DNA (gene) complex as an "immunogene." The fluorescent microscopic observation showed that the immunoporter as well as immunogene bound specifically to the EGF receptors on the cell surface, and the loaded reporter gene, such as beta-galactosidase (beta-GAL), was detected in the cell nucleus at 2 hours after transfection. The enzyme activity from the beta-GAL gene was detected at 12 hours and increased for 3 to 5 days. Similar kinetics were obtained for another reporter gene, chloramphenicol acetyltransferase. Furthermore, the immunoporter delivered the herpes simplex virus thymidine kinase gene and induced substantial suicide effects on tumor cells when gancyclovir or acyclovir was added. Thus, the immunogene approach was successful in delivering therapeutic genes to EGF receptor overexpressing tumor cells. Further technical refinement may prove useful as a supplementary treatment of patients with squamous cell carcinomas.

Acyclovir↗

PubMedDate not supplied

Receptor-mediated gene delivery using the Fab fragments of anti-epidermal growth factor receptor antibodies: improved immunogene approach.

We previously developed the "immunogene" approach toward cancer gene therapy using epidermal growth factor receptor (EGFR)-mediated endocytosis. Here, we describe an improved immunogene system, in which the antigen-binding (Fab) fragments of the monoclonal antibody (Ab) B4G7 against the human EGFR were conjugated with poly-L-lysine to form a gene delivery vehicle (designated Fab "immunoporter"). Within 12 hours, the beta-galactosidase beta-gal) gene was transferred via the Fab immunoporter to virtually all of the nuclei of human squamous carcinoma A431 cells that overproduce the EGFR, and the beta-gal enzyme activity was detected within 24 hours and retained for more than 3 days. The beta-gal gene was not transferred into human and mouse cells that were deficient in EGFRs, but it was delivered if those mouse cells were transformed with human EGFR genes. Beta-gal gene transfer via the Fab immunoporter was inhibited by pretreatment with excess amounts of the Fab fragment. The transfer efficiency of the beta-gal gene to A431 cells via the Fab immunoporter was approximately 2%, which is as high as the lipofection method and 20- to 100-fold higher than the whole Ab immunoporter. The transfer of the herpes simplex virus thymidine kinase gene into A431 tumor cells as a form of the thymidine kinase/Fab immunogene was successful, and subsequent treatment with ganciclovir induced remarkable suicide effects which conferred 1000-fold higher drug sensitivity. Thus, the Fab immunogene was substantially improved with regard to the whole Ab immunogene and could be used as a potent gene transfer vehicle for the in vivo targeting of EGFR-hyperproducing tumor cells.

Animals↗