Human bladder cancer cells undergo cisplatin-induced apoptosis that is associated with p53-dependent and p53-independent responses.
Cisplatin is a first-line chemotherapeutic agent and a powerful component of standard treatment regimens for several human malignancies including bladder cancer. DNA-Pt adducts produced by cisplatin are mainly responsible for cellular toxicity and induction of apoptosis. Identification of the mechanisms that control sensitivity to cisplatin is central to improving its therapeutic index and to successfully encountering the acquired resistance frequently emerging during therapy. In the present study, using MTT-based assays, Western blotting and semi-quantitative RT-PCR, we examined the apoptosis-related cellular responses to cisplatin exposure in two human urinary bladder cancer cell lines characterized by different malignancy grade and p53 genetic status. Both RT4 (grade I; wild-type p53) and T24 (grade III; mutant p53) cell types proved to be vulnerable to cisplatin apoptotic activity, albeit in a grade-dependent and drug dose-specific manner, as demonstrated by the proteolytic processing profiles of Caspase-8, Caspase-9, Caspase-3, and the Caspase repertoire characteristic substrates PARP and Lamin A/C, as well. The differential resistance of RT4 and T24 cells to cisplatin-induced apoptosis was associated with an RT4-specific phosphorylation (Ser15; Ser392) pattern of p53, together with structural amputations of the Akt and XIAP anti-apoptotic regulators. Furthermore, cisplatin administration resulted in a Granzyme B-mediated proteolytic cleavage of Hsp90 molecular chaperone, exclusively occurring in RT4 cells. To generate functional networks, expression analysis of a number of genes, including Bik, Bim, Bcl-2, FAP-1, Fas, FasL, TRAIL, Puma, Caspase-10, ATP7A, ATP7B and MRP1, was performed, strongly supporting the role of p53-dependent and p53-independent transcriptional responses in cisplatin-induced apoptosis of bladder cancer cells.
Konstantakou
Eumorphia G
EG
Department of Cell Biology, Faculty of Biology, University of Athens, Panepistimiopolis, Zografou 157 84, Greece.
Voutsinas
Gerassimos E
GE
Karkoulis
Panagiotis K
PK
Aravantinos
Gerasimos
G
Margaritis
Lukas H
LH
Stravopodis
Dimitrios J
DJ
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053455:Caspase 10 / Q000235:genetics; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D050687:E2F1 Transcription Factor / Q000502:physiology; D053804:Granzymes / Q000502:physiology; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000473:pathology; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000502:physiology; D019014:fas Receptor / Q000235:genetics
D000970:Antineoplastic Agents; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D018841:HSP90 Heat-Shock Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D016159:Tumor Suppressor Protein p53; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D019014:fas Receptor; D051057:Proto-Oncogene Proteins c-akt; D053804:Granzymes; D053455:Caspase 10; D002945:Cisplatin