Phorbol Ester Facilitates Apoptosis in Murine Fibroblasts Pretreated by Mild Ultraviolet Radiation
Although phorbol 12-myristate 13-acetate (PMA) inhibits apoptosis and promotes the growth of some types of cells, it induces apoptosis in other cells. We evaluated the apoptotic effects of PMA on murine fibroblasts (L-929) that had been exposed to ultraviolet-B (UV-B) radiation at 312 nm, which prom...
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Published in | Journal of biochemistry (Tokyo) Vol. 126; no. 2; pp. 340 - 346 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
England
Oxford University Press
01.08.1999
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Subjects | |
Online Access | Get full text |
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Summary: | Although phorbol 12-myristate 13-acetate (PMA) inhibits apoptosis and promotes the growth of some types of cells, it induces apoptosis in other cells. We evaluated the apoptotic effects of PMA on murine fibroblasts (L-929) that had been exposed to ultraviolet-B (UV-B) radiation at 312 nm, which promotes tumor cell growth. Exposure to PMA alone did not induce Fas, Fas-L, or apoptosis. Cells exposed to mild UV-B irradiation (80 J/m2) alone exhibited a slight expression of Fas and Fas-L 36 to 48 h after the exposure, and exhibited apoptosis as evidenced by DNA fragmentation 72 h after exposure. The addition of PMA (0.8X10-5 to 3.2xl0-5M) to the medium 24h after the UV-B exposure markedly and dose-dependently enhanced these cell responses. Confluent untreated cells, cells cocultured with PMA, and cells cocultured with PMA for 24 h after the UV-B exposure consistently expressed mRNAs for wild-type p53, bcl-2y and ICE. Expression of c-myc mRNA was initially observed, but became undetectable in the cells cocultured for 24 h with a high concentration of PMA (3.2xl0-5M) following UV-B exposure. Such cells subsequently exhibited the maximal apoptotic response. We conclude that mild exposure to UV-B altered murine fibroblast cells in such a way as to facilitate their death by apoptosis upon addition of PMA. |
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Bibliography: | istex:9CF3B8C070F7FAA054E4E1B9D92C222E63BB795A ArticleID:126.2.340 ark:/67375/HXZ-XRKHHGXN-0 |
ISSN: | 0021-924X 1756-2651 |
DOI: | 10.1093/oxfordjournals.jbchem.a022455 |