TY - JOUR
T1 - Involvement of FLIP in 2-methoxyestradiol-induced tumor regression in transgenic adenocarcinoma of mouse prostate model
AU - Ganapathy, Manonmani
AU - Ghosh, Rita
AU - Jianping, Xie
AU - Zhang, Xiaoping
AU - Bedolla, Roble
AU - Schoolfield, John
AU - Yeh, I. Tien
AU - Troyer, Dean A.
AU - Olumi, Aria F.
AU - Kumar, Addanki P.
PY - 2009/3/1
Y1 - 2009/3/1
N2 - Purpose: The purpose of this study is to investigate whether Fas-associated death domain interleukin-1 converting enzyme like inhibitory protein (FLIP) inhibition is a therapeutic target associated with 2-methoxyestradiol (2-ME 2) - mediated tumor regression. Experimental Design: Expression and levels of FLIP were analyzed using (a) real-time PCR and immunoblot analysis in androgen-independent PC-3 cells treated with the newly formulated 2-ME 2 and (b) immunohistochemistry in different Gleason pattern human prostate tumors. Transient transfections and chromatin immunoprecipitation (ChIP) assays were used to identify the transcription factors that regulate FLIP. Involvement of FLIP in 2-ME 2-induced tumor regression was evaluated in transgenic adenocarcinoma mouse prostate (TRAMP) mice. Results: High Gleason pattern (5+5) human prostate tumors exhibit significant increase in FLIP compared with low Gleason pattern 3+3 (P = <0.04). 2-ME 2 reduced the levels and promoter activity of FLIP (P = 0.001) in PC-3 cells. Transient expression assays show sequences between -503/+242 being sufficient for 2-ME 2- induced inhibition of FLIP promoter activity. Cotransfection experiments show that overexpression of Sp1 activated, whereas Sp3 inhibited, Sp1 transactivation of FLIP promoter activity (P = 0.0001). 2-ME 2 treatment reduced binding of Sp1 to the FLIP promoter as evidenced by ChIP. Further, levels of FLIP associated with Fas or FADD decreased, whereas cleavage of caspase-8, levels of Bid, and apoptosis increased in response to 2-ME 2 treatment in PC-3 cells. Administration of 2-ME 2 regressed established prostate tumors in TRAMP mice that were associated with reduced expression of FLIP and Sp1. Conclusion: Targeting Sp1-mediated FLIP signaling pathway may provide a novel approach for prostate cancer management.
AB - Purpose: The purpose of this study is to investigate whether Fas-associated death domain interleukin-1 converting enzyme like inhibitory protein (FLIP) inhibition is a therapeutic target associated with 2-methoxyestradiol (2-ME 2) - mediated tumor regression. Experimental Design: Expression and levels of FLIP were analyzed using (a) real-time PCR and immunoblot analysis in androgen-independent PC-3 cells treated with the newly formulated 2-ME 2 and (b) immunohistochemistry in different Gleason pattern human prostate tumors. Transient transfections and chromatin immunoprecipitation (ChIP) assays were used to identify the transcription factors that regulate FLIP. Involvement of FLIP in 2-ME 2-induced tumor regression was evaluated in transgenic adenocarcinoma mouse prostate (TRAMP) mice. Results: High Gleason pattern (5+5) human prostate tumors exhibit significant increase in FLIP compared with low Gleason pattern 3+3 (P = <0.04). 2-ME 2 reduced the levels and promoter activity of FLIP (P = 0.001) in PC-3 cells. Transient expression assays show sequences between -503/+242 being sufficient for 2-ME 2- induced inhibition of FLIP promoter activity. Cotransfection experiments show that overexpression of Sp1 activated, whereas Sp3 inhibited, Sp1 transactivation of FLIP promoter activity (P = 0.0001). 2-ME 2 treatment reduced binding of Sp1 to the FLIP promoter as evidenced by ChIP. Further, levels of FLIP associated with Fas or FADD decreased, whereas cleavage of caspase-8, levels of Bid, and apoptosis increased in response to 2-ME 2 treatment in PC-3 cells. Administration of 2-ME 2 regressed established prostate tumors in TRAMP mice that were associated with reduced expression of FLIP and Sp1. Conclusion: Targeting Sp1-mediated FLIP signaling pathway may provide a novel approach for prostate cancer management.
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U2 - 10.1158/1078-0432.CCR-08-1389
DO - 10.1158/1078-0432.CCR-08-1389
M3 - Article
C2 - 19223508
AN - SCOPUS:63449135315
SN - 1078-0432
VL - 15
SP - 1601
EP - 1611
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 5
ER -