title: Induction of anchorage-independent growth of JB6 mouse epidermal cells by 1 alpha,25-dihydroxyvitamin D3.
abstract: 1 alpha,25-Dihydroxyvitamin D3 [1 alpha,25(OH)2D3], a hormonally active form of vitamin D3, was shown previously to enhance chemically induced transformation of BALB 3T3 cells and Syrian hamster embryo cells. This report demonstrates that 1 alpha,25(OH)2D3, like phorbol ester tumor promoters, induces anchorage-independent growth of mouse JB6 epidermal cells. When plated on agar plates containing 1 alpha,25(OH)2D3 at concentrations higher than 0.05 ng/ml or 0.12 nM, JB6 cells formed colonies on the surface of agar plates dose dependently. This anchorage-independent growth was further confirmed by stimulation of DNA synthesis after liquefying the agar layer with NaI. A phorbol-ester resistant variant of JB6 cells was also resistant to 1 alpha,25(OH)2D3 in terms of induction of anchorage independency. Induction of anchorage-independent growth was specific for 1 alpha,25(OH)2D3: other derivatives of vitamin D3 also induced colony formation on agar plates but only at a higher concentration (500 ng/ml) and to much less extent than did 1 alpha,25(OH)2D3. JB6 cells were found to contain a receptor specific for 1 alpha,25(OH)2D3 with a Kd of 55.7 pM and Nmax of 102.5 fmol/mg protein, suggesting a receptor-mediated mechanism of the induction. The clone that was resistant to 1 alpha,25(OH)2D3 also contained the receptor. DNA-cellulose chromatography showed that a 1 alpha,25(OH)2D3-receptor complex interacted with DNA. In contrast to 1 alpha,25(OH)2D3, retinoic acid did not induce anchorage-independent growth of JB6 cells, but it inhibited the induction by 1 alpha,25(OH)2D3 when applied with it.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D004247:DNA / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D000078404:Epidermal Cells; D051379:Mice; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D002273:Carcinogens; D004268:DNA-Binding Proteins; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D014212:Tretinoin; D004247:DNA; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate