Progression of hormone-dependent adenocarcinoma cells to hormone-independent spindle carcinoma cells in vitro in a clonal spontaneous rat mammary tumor cell line.
A hormone-dependent, clonal carcinoma cell line, designated RM22-F5, was derived from a malignant mammary mixed tumor spontaneously arising in an outbred old female Wistar rat. These cells expressed keratin and desmosomal protein and formed epithelial monolayers in a growth factor and hormone-supplemented medium (LHC-8) containing 10% fetal bovine serum (E-type cells). Cells subcultured for 6 to 8 passages in RPMI 1640 medium containing 10% fetal bovine serum without supplements appeared to be fibroblastic and expressed vimentin (F-type cells). The shift to a fibroblast-like morphology was associated with a more malignant phenotype which included rapid, hormone-independent growth and invasive sarcoma-like character in nude mice. F-type cells were no longer able to express their original epithelial phenotype in LHC-8 medium. Cytogenetic analysis revealed that both E- and F-type cells had essentially the same karyotype. Analysis of PCR-amplified DNA further demonstrated a point mutation of the H-ras-1 gene at codon 12 and loss of the normal H-ras-1 allele in both cell types. Genetic tagging of E-type cells with the neomycin-resistance gene resulted in the generation of F-type cells with neomycin resistance in RPMI 1640 medium, suggesting that F-type cells are a malignant variant of E-type cells arising during in vitro culture. Somatic cell fusion between E- and F-type cells revealed that with most hybrid clones tested, the fibroblast-like phenotype was greatly suppressed. These results suggest that an irreversible phenotypic transition, representative of tumor progression from hormone-dependent adenocarcinoma to more malignant hormone-independent spindle carcinoma cells, is a recessive event and may involve loss of a suppressor function.
Nakanishi
H
H
Laboratory of Biological Chemistry, National Institute on Aging, Baltimore, Maryland 21224.
Taylor
R M
RM
Chrest
F J
FJ
Masui
T
T
Utsumi
K
K
Tatematsu
M
M
Passaniti
A
A
D000230:Adenocarcinoma / Q000737:chemistry / Q000235:genetics / Q000473:pathology*; D000818:Animals; D001483:Base Sequence; D002277:Carcinoma / Q000737:chemistry / Q000235:genetics / Q000473:pathology*; D002455:Cell Division; D002459:Cell Fusion; D002471:Cell Transformation, Neoplastic / Q000737:chemistry / Q000235:genetics / Q000473:pathology*; D003470:Culture Media; D003896:Desmosomes / Q000737:chemistry; D005260:Female; D005434:Flow Cytometry; D011905:Genes, ras / Q000235:genetics; D007633:Keratins / Q000032:analysis; D015674:Mammary Neoplasms, Animal / Q000737:chemistry / Q000235:genetics / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009355:Neomycin; D009361:Neoplasm Invasiveness; D009376:Neoplasms, Hormone-Dependent / Q000737:chemistry / Q000235:genetics / Q000473:pathology*; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000473:pathology; D014746:Vimentin / Q000032:analysis
D003470:Culture Media; D014746:Vimentin; D007633:Keratins; D009355:Neomycin