title: Growth factor interactions between mouse mammary cell lines cocultured in collagen gels.
abstract: Three related mouse mammary cell lines were cultured in collagen gels and assayed for growth factor responsiveness and interaction via soluble factors. The CL-S1 cell line is nontumorigenic and grows poorly in collagen gel culture. The +SA and -SA cell lines exhibit different degrees of malignant behavior in vivo and have different growth properties in vitro. In collagen gel culture, +SA growth was stimulated by serum but not by epidermal growth factor (EGF), whereas both serum and EGF were required for optimal growth of -SA cells of early passage number as well as CL-S1 cells. -SA cells of later passage repeatedly exhibited a change so as to no longer require serum while retaining EGF responsiveness. [125I]EGF binding analyses indicated that CL-S1 cells bound EGF with less affinity than did -SA cells whereas +SA cells bound almost no ligand. When cell lines were maintained in separate collagen gels but shared the same culture medium, growth of +SA or -SA cells was slightly enhanced in the presence of CL-S1 cells and -SA cell growth was enhanced by the presence of +SA cells. Using the normal rat kidney fibroblast line NRK (clone 49F) as an indicator, serum-containing conditioned media from each cell line and from each pair of cell lines cultured in collagen gels were tested for transforming growth factor (TGF) activity. Both the -SA and CL-S1 lines tested positive for TGF-alpha production and possibly released a TGF-beta activity. These results suggest mechanisms by which cell populations in and around tumors can modify one another's growth characteristics.
authors.affiliation: Department of Microbiology, Montana State University, Bozeman.
authors.forename: S
authors.initials: S
authors.lastname: Hamner
authors.forename: W
authors.initials: W
authors.lastname: Jones
authors.forename: J R
authors.initials: JR
authors.lastname: Starkey
authors.forename: H L
authors.initials: HL
authors.lastname: Hosick
mesh_terms: D000818:Animals; D002450:Cell Communication; D003094:Collagen; D003470:Culture Media / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005782:Gels; D006133:Growth Substances / Q000502:physiology*; D008325:Mammary Neoplasms, Experimental / Q000473:pathology*; D051379:Mice; D015291:Transforming Growth Factors / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000166:cytology
chemical_list: D003470:Culture Media; D005782:Gels; D006133:Growth Substances; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors; D003094:Collagen