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TNF receptor 1 is involved in the induction of apoptosis by the cyclin‐dependent kinase inhibitor p27 Kip1 in the prostate cancer cell line PC‐3
Author(s) -
Jaruga-Killeen Ewa,
Rayford Walter
Publication year - 2005
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.04-2305fje
Subject(s) - apoptosis , cell cycle , cancer research , programmed cell death , biology , microbiology and biotechnology , tunel assay , prostate cancer , population , cancer , medicine , biochemistry , genetics , environmental health
Loss of p27 Kip1 , a cyclin‐dependent kinase inhibitor, is observed in aggressive prostate cancers. We demonstrated that intratumoral injections of recombinant adenovirus overexpressing p27 Kip1 (Adp27) reduced the growth of prostate cancer xenografts in nude mice. Presently, we studied the mechanism(s) of cell death induced by Adp27 in prostate cancer cell line PC‐3. Cells were infected with Adp27 and compared with those infected by empty virus or were non‐infected. Cell cycle and typical markers of apoptosis were analyzed by flow cytometry in the presence of the following reagents: cycloheximide, pan‐caspase inhibitor ZVAD‐fmk, neutralizing anti‐TNFR1, and anti‐TNFR2. Ooverexpression of p27 Kip1 protein and cell cycle arrest were noted within 24 h after Adp27‐infection. Sub‐G1 fraction, chromatin margination, and phosphatidylserine exposure were evident by the third day of treatment. Cycloheximide elevated sub‐G1 fraction in Adp27‐ infected cells by threefold, while ZVAD‐fmk reduced sub‐G1 to control levels. Caspase‐ dependent apoptosis occurred in a third of the population, while two‐thirds were ZVAD‐fmk insensitive but TUNEL‐positive. Flow cytometry showed increased expression of TNFR1 and TNFR2 in Adp27‐infected cells. Neutralizing anti‐TNFR1 decreased TUNEL‐positive score, while anti‐TNFR2 did not affect p27 Kip1 ‐induced apoptosis. This is the first report showing that p27 Kip1 induces caspase‐dependent and ‐independent stages of cell death that may involve TNF‐ signaling through TNFR1.