Control of angiogenic activity in carcinogen-initiated and neoplastic hamster pouch keratinocytes and their hybrid cells.
This study was undertaken to test the hypothesis that deregulated expression of the angiogenic phenotype by tumor cells is due to loss or inactivation of an angiogenesis suppressor gene(s). We used the technique of somatic cell hybridization to test the ability of untreated or chemical carcinogen-initiated hamster pouch keratinocytes, when fused to squamous epithelial neoplasms, to suppress tumor angiogenic activity by assaying hybrid-conditioned media (CM) in the avascular cornea of rat eyes. A non-angiogenic keratinocyte line, CL-2, derived from cultures of untreated epithelium and 3 lines of carcinogen-initiated keratinocytes, PN3, 5, and 7, of varying angiogenic potential were fused, using polyethylene glycol, to 3 tumorigenic, potently angiogenic, drug-resistant, hamster pouch carcinomas cell lines: HCPC-1, AW16E1-1, and AW16 E1-2. Serum-free 48-h CM from hybrid clones was prepared and assayed for angiogenic activity in rat corneas. CM from 5 hybrid clones derived from normal x neoplastic keratinocytes failed to induce an angiogenic response in 28 of 29 (97%) corneas tested. In contrast, CM from 4 hybrid clones derived from fusions between carcinogen-initiated and tumor cells were potently angiogenic in 24 of 25 (96%) corneas tested. Two angiogenesis suppressed hybrids clones were propagated in culture for an extended period of time, to permit chromosome segregation, and were found to re-express the angiogenic phenotype. These result indicate that angiogenesis is a recessive trait in normal hamster keratinocytes which is regulated in trans in these hybrid cells. It would also appear that loss or inactivation of angiogenesis suppressor function occurs early in the neoplastic process.
Polverini
P J
PJ
Department of Pathology, Northwestern University Schools of Medicine and Dentistry, Chicago, IL 60611.
Shimizu
K
K
Solt
D B
DB
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002196:Capillaries / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000098:blood supply / Q000139:chemically induced / Q000235:genetics*; D002459:Cell Fusion; D002460:Cell Line; D003315:Cornea; D006224:Cricetinae; D004848:Epithelium / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006822:Hybrid Cells / Q000502:physiology*; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D051381:Rats; D011916:Rats, Inbred F344; D013489:Suppression, Genetic
D015127:9,10-Dimethyl-1,2-benzanthracene