Abstract
Therapeutic efficacy of cisplatin-based treatment of late stage urothelial carcinoma (UC) is limited by chemoresistance. To elucidate underlying mechanisms and to develop new approaches for overcoming resistance, we generated long-term cisplatin treated (LTT) UC cell lines, characterised their cisplatin response, and determined the expression of molecules involved in cisplatin transport and detoxification, DNA repair, and apoptosis. Inhibitors of metallothioneins and Survivin were applied to investigate their ability to sensitise towards cisplatin. Cell growth, proliferation, and clonogenicity were examined after cisplatin treatment by MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, EdU (5-ethynyl-2’-deoxyuridine) incorporation assay, and Giemsa staining, respectively. Cell cycle distribution and apoptosis were quantified by flow cytometry. mRNA and protein expressions were measured by real-time quantitative (qRT)-PCR, western blot, or immunofluorescence staining. LTTs recovered rapidly from cisplatin stress compared to parental cells. In LTTs, to various extents, cisplatin exporters and metallothioneins were induced, cisplatin adduct levels and DNA damage were decreased, whereas expression of DNA repair factors and specific anti-apoptotic factors was elevated. Pharmacological inhibition of Survivin, but not of metallothioneins, sensitised LTTs to cisplatin, in an additive manner. LTTs minimise cisplatin-induced DNA damage and evade apoptosis by increased expression of anti-apoptotic factors. The observed diversity among the four LTTs highlights the complexity of cisplatin resistance mechanisms even within one tumour entity, explaining heterogeneity in patient responses to chemotherapy.
Highlights
Bladder cancer (BC) is the 9th most common tumour world-wide and the most common cancer of the urinary tract [1]
Further findings of the present study demonstrate the presence of pre, on- and post-target mechanisms underlying cisplatin resistance, but to various degrees, in each of the four resistant urothelial carcinomas (UC) cell lines, with a important role for Survivin-dependent anti-apoptotic signalling
Four cisplatin-resistant long-term cisplatin treated (LTT) sublines were generated from the UC cell lines (UCCs) RT-112, J82, 253J, and T-24 [16,33]
Summary
Bladder cancer (BC) is the 9th most common tumour world-wide and the most common cancer of the urinary tract [1]. Factors contributing to cisplatin resistance are usually categorised as mediating pre-target (transport, metabolism), on-target (DNA-cisplatin adduct formation, DNA-damage response), or post-target (evasion of apoptosis, cell-cycle arrest) resistance [6,7,8,9]. Efflux of unconjugated cisplatin is likely mediated by the Transporting P-type Adenosine Triphosphatases ATP7A and ATP7B [20] Overexpression of these transmembrane carriers has been implicated in cisplatin resistance and poor patient survival in oral squamous cell carcinoma [21]. On-target mechanisms like alterations in DNA damage responses have been observed in cancers. Further findings of the present study demonstrate the presence of pre-, on- and post-target mechanisms underlying cisplatin resistance, but to various degrees, in each of the four resistant UC cell lines, with a important role for Survivin-dependent anti-apoptotic signalling
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
