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Role of prostanoids and lipid peroxides as mediators of the 12‐O‐tetradecanoylphorbol‐13‐acetate effect on cell growth
Author(s) -
Morisaki Nobuhiro,
Tomei L. David,
Milo George E.,
Cornwell David G.
Publication year - 1985
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534286
Subject(s) - 12 o tetradecanoylphorbol 13 acetate , prostanoid , arachidonic acid , chemistry , radioimmunoassay , tetradecanoylphorbol acetate , endocrinology , medicine , prostaglandin , lipidology , biochemistry , clinical chemistry , biology , protein kinase c , signal transduction , phorbol ester , enzyme
Confluent cultures of guinea pig smooth muscle cells (SMC) or human fibroblasts (HNF) were treated with 12‐tetradecanoylphorbol‐13‐acetate (TPA). Prostanoid levels were measured by the radioimmunoassay of 6‐keto‐PGF 1α and PGE 2 , and lipid peroxides were measured by the thiobarbituric acid test for malondialdehyde (MDA). Cells were seeded at low densities, and growth was calculated both from the cell count (Coulter Counter) and the colony number (image analysis). When confluent SMC and HNF were incubated in media alone, 6‐keto‐PGF 1α levels were a function of the TPA concentration, increasing to a maximum at 10 −8 M TPA and then decreasing at higher TPC concentrations. When confluent SMC and HNF were incubated in media containing exogenous arachidonic acid, 6‐keto‐PGF 1α levels again increased to a maximum at 10 −8 M TPA but decreased at higher TPA concentrations only with SMC. The increase in 6‐keto‐PGF 1α levels was much greater in HNF (1310%) than SMC (680%). SMC synthesized similar amounts of 6‐keto‐PGF 1α and PGE 2 , and the stimulatory effect of TPA was similar with 6‐keto‐PGF 1α and PGE 2 . Indomethacin (IM) blocked prostanoid synthesis at all TPA concentrations. TPA did not have a significant effect on MDA levels in either cell line. The lipid antioxidants α‐tocopherol and α‐tocopherylquinone blocked lipid peroxidation without affecting the stimulation of prostanoid synthesis with TPA. Cell number decreased to a minimum at 10 −8 M TPA in both cell lines. The decrease in cell number was much greater in HNF (72%) than SMC (30%). SMC colony number decreased at 10 −8 TPA and then increased at 10 −6 M TPA. IM did not block the TPA effect on cell number in either cell line. The lipid antioxidant butylated hydroxytoluene (BHT) did not block the TPA effect on SMC cell number. The IM and the BHT data show that the TPA effect on cell growth is not mediated by prostanoid or lipid peroxide products of arachidonic acid metabolism. However, the increase in prostanoid synthesis parallels the decrease in cell number, and the effects are maximal at the same TPA concentration. These correlations suggest a common cellular process affecting both prostanoid synthesis and cell growth that is initiated or enhanced by TPA.