Estrogen induction of the granzyme B inhibitor, proteinase inhibitor 9, protects cells against apoptosis mediated by cytotoxic T lymphocytes and natural killer cells.
Exposure to estrogens is associated with an increased risk of developing breast, cervical, and liver cancer. Estrogens strongly induce the human granzyme B inhibitor, proteinase inhibitor 9 (PI-9). Because cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells use the granzyme pathway to induce apoptosis of target cells, we tested the ability of activated CTLs and the human NK cell line, YT cells, to lyse human liver cells. Estrogen induction of PI-9 protected the liver cells against CTL and NK cell-mediated, granzyme-dependent, apoptosis. Knockdown of PI-9 by RNA interference blocked the protective effect of estrogen. This work demonstrates that estrogens can act on target cells to control their destruction by immune system cells and shows that induction of PI-9 expression can inhibit both CTL and NK cell-mediated apoptosis. Estrogen induction of PI-9 may reduce the ability of cytolytic lymphocytes-mediated immune surveillance to destroy newly transformed cells, possibly providing a novel mechanism for an estrogen-mediated increase in tumor incidence.
Jiang
Xinguo
X
Department of Biochemistry, B-4 RAL, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Orr
Brent A
BA
Kranz
David M
DM
Shapiro
David J
DJ
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002460:Cell Line; D002461:Cell Line, Transformed; D003433:Crosses, Genetic; D053938:DNA Fragmentation; D004815:Epidermal Growth Factor / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology; D005434:Flow Cytometry; D053804:Granzymes; D006801:Humans; D007694:Killer Cells, Natural / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D015233:Models, Statistical; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000378:metabolism*; D015843:Serpins / Q000096:biosynthesis*; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism* / Q000473:pathology
D004967:Estrogens; C102316:SERPINB9 protein, human; D015843:Serpins; D000431:Ethanol; D004815:Epidermal Growth Factor; C509213:GZMB protein, human; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases