Human bladder cancer cells undergo cisplatin-induced apoptosis that is associated with p53-dependent and p53-independent responses

Abstract

Abstract.Cisplatin is a first-line chemotherapeutic agent and a powerful component of standard treatment regimens for several human malignancies including bladder cancer. DNAPt 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, Fas, FasL, TRAIL, Puma, 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. IntroductionWith its incidence continuing to increase, bladder cancer is classified among the five most common malignancies in industrialized countries (1). Forming a worldwide estimate over one million patients, bladder cancer is clearly considered a significant public health issue around the world (2). The three main types of cancer affecting bladder are transitional cell carcinoma (TCC), squamous cell carcinoma (SCC) and adenocarcinoma (ADC), with TCC representing >90% of all bladder cancers. Four clinically distinct entities of TCC have been recognized: superficial, papillary tumors (Ta and T1), carcinoma in situ (Tis), muscle-invasive tumors (T2-T4) and advanced disease, involving extra-pelvic nodal or distant metastasis (3,4). Metastatic TCC demonstrates a moderate sensitivity to chemotherapy while a significant variation in patient survival rates and activity levels of individual regimens has been observed (5).Cisplatin-based combination chemotherapy protocols, such as MVAC (methotrexate-vinblastine-adriamycin-cisplatin), constituted for a number of years standard treatment of patients with advanced (or metastatic) urothelial bladder cancer. However, due to the MVAC-induced systemic toxici...

First use of Cisplatin as Chemotherapy for Treatment of Surgically-Excised Cutaneous Squamous Cell Carcinoma in Dromedary Camels: A Preliminary Report

“…Of these drugs, cisplatin (cisdichlorodiammineplatinum (II) or cis-DDP) is a major chemotherapeutic agent used on a wide range as anticancer agent in human medicine and also in animals. Cisplatin is a broad-spectrum antineoplastic drug that can be used for different kinds of tumors in humans including that affect ovary, testis, urinary bladder, cervix and lungs as well as neck and head cancers (Konstantakou et al 2009).…”