Restoration of p53 expression sensitizes human papillomavirus type 16 immortalized human keratinocytes to CD95-mediated apoptosis

被引:46
作者
Aguilar-Lemarroy, A
Gariglio, P
Whitaker, NJ
Eichhorst, ST
zur Hausen, H
Krammer, PH
Rösl, F
机构
[1] Deutsch Krebsforschungszentrum, Forsch Schwerpunkt Angew Tumorvirol, Abt Tumorvirus Immunol, D-69120 Heidelberg, Germany
[2] Inst Politecn Nacl, CINVESTAV, Dept Mol Biol & Genet, Mexico City, DF, Mexico
[3] Univ New S Wales, Sch Biochem & Mol Genet, Sydney, NSW 2052, Australia
[4] Deutsch Krebsforschungszentrum, Forsch Schwerpunkt Tumorimmunol, D-69120 Heidelberg, Germany
关键词
CD95; cervical cancer; myc; p53; HPV; proteasome inhibitor;
D O I
10.1038/sj.onc.1204979
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
To understand the function of the individual oncogenes of HPV16 in modulating the cellular response to apoptogenic signals, we used human keratinocytes immortalized with either E6, E7 or E6/E7 oncoproteins as model system. Applying CD95 antibodies or recombinant CD95 ligand, only the E7-immortalized cells underwent extensive apoptosis. In contrast, E6- and E6/E7-expressing keratinocytes were resistant. Dominance of E6 correlated with significant down-regulation of p53, c-Myc, p21 and Bcl-2. CD95 was found to be reduced in resistant HPV-positive cells, while there were no quantitative differences in expression levels of FADD, FLICE/caspase-8 or caspase-3. Notably, in contrast to primary human keratinocytes, all immortalized cells showed a general reduction of c-FLIP, an inhibitory protein which normally prevents unscheduled CD95-induced apoptosis. E6- and E6/E7-positive keratinocytes, however, can be sensitized to CD95 apoptosis by blocking proteasome-mediated proteolysis. CD95-resistant HPV-positive cells underwent apoptosis within 3-5 h upon co-incubation with MG132 and agonistic antibodies or CD95 ligand, which was preceded by a strong re-expression of p53 and c-Myc, but not of other half-life controlled proteins such as Bax or I kappaB alpha. Blockage of proteasomal activity alone did not result in apoptosis, although the same set of pro-apoptotic proteins was up-regulated. Performing similar experiments with cervical carcinoma cells expressing mutated p53 (C33a) or with P53-'null' lung carcinoma cells (H1299), no CD95 cell killing occurred eventhough c-Myc was strong induced. These data indicate that the reduced bioavailability of p53 is a key-regulatory event in perturbation of CD95 signaling in HPV16 immortalized keratinocytes.
引用
收藏
页码:165 / 175
页数:11
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