title: Induction of granulocyte-macrophage colony-stimulating activity by 12-O-tetradecanoylphorbol-13-acetate in SENCAR and B6C3F1 mice.
abstract: Previous studies in this laboratory and others have indicated that 12-O-tetradecanoylphorbol-13-acetate (TPA), the most potent skin tumor promoter known, evokes significantly greater inflammatory responses in phorbol ester-sensitive (SENCAR) mice compared to strains (e.g. C57BL/6 and B6C3F1) that are relatively resistant to the outgrowth of skin tumors in two-stage chemically induced carcinogenesis protocols. In the studies reported herein, subchronic topical application of TPA at doses relevant to two-stage protocols induced serum granulocyte-macrophage colony-stimulating activity (GM-CSA) in both SENCAR and B6C3F1 mice; however, the increase in SENCAR mice was significantly greater than that observed in the relatively resistant B6C3F1 strain (5-fold versus a 2-fold increase respectively). The greater increase in serum GM-CSA observed in SENCAR mice was correlated with a 31% increase in the number of splenic leukocytes that lacked both B and T cell surface markers (i.e. double-negative cells), a presumed GM progenitor cell; no significant increase in the relative percentage of such cells was observed in B6C3F1 mice. Alternatively, significant decreases in splenic T lymphocytes (23 and 32% in SENCAR and B6C3F1 respectively) were observed in both strains of TPA-treated mice and may, in part, account for the previously observed decreases in splenic cell blastogenic response to the T cell mitogen phytohemagglutinin (PHA). In vitro incubation of splenic cells from SENCAR mice with 0.01-1.0 microM TPA led to significantly greater increases in colony formation relative to splenic cells isolated from B6C3F1 mice; therefore, differences in the biochemical responsiveness between strains may occur at the level of signal transduction in splenic GM progenitor cells. In conclusion, these studies indicated that strain-dependent differences in the systemic inflammatory response following topical application of TPA may result from direct stimulation of splenic GM precursor cells by TPA and/or may occur, indirectly, through the release of cytokines [e.g. GM colony-stimulating factor (GM-CSF)] by induced epidermal (or other) cells.
authors.affiliation: Department of Pharmacology and Toxicology, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, IN 47907.
authors.forename: L W
authors.initials: LW
authors.lastname: Updyke
authors.forename: H L
authors.initials: HL
authors.lastname: Yoon
authors.forename: R W
authors.initials: RW
authors.lastname: Pfeifer
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002452:Cell Count / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis* / Q000097:blood; D051379:Mice; D008815:Mice, Inbred Strains / Q000502:physiology*; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000954:Antigens, Surface; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013755:Tetradecanoylphorbol Acetate