Expression of Multidrug Resistance
Gene Product (P-Glycoprotein) in
Transitional Cell Carcinomas of the
Upper Urinary Tract

Shinohara, Nobuo; Nonomura, K.N.; Takakura, Fujio; Hamada, Michito; Hb, Grossman; Koyanagi, Takahiro

doi:10.1159/000475409

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…Clinically, Park et al [ 26] reported that p‐glycoprotein was expressed in 75% of cystectomy specimens from patients with invasive bladder cancer who had no prior exposure to chemotherapeutic drugs, which contrasts with the low expression rate (23%) in cultured TCC cell lines reported previously [ 17]. Shinohara et al studied the p‐glycoprotein expression in TCC of the upper urinary tract reporting that it was expressed in a quarter of cases and serves as a prognostic indicator in patients with these tumours who are treated with MDR regimens [ 27]. Although clinical TCC specimens express p‐glycoprotein, Park et al [ 26] reported no increase in therapeutic efficacy with combinations of verapamil and doxorubicin administered intravesically to prevent tumour recurrence.…”

Section: Discussionmentioning

confidence: 99%

Characterization and modulation of transitional cell carcinoma cell lines with acquired multidrug resistance

Chang

1998

British Journal of Urology

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Objectives To characterize in vitro drug‐induced multidrug resistance (MDR) in transitional cell carcinoma (TCC) cell lines, and to elucidate the possible mechanisms of acquired MDR and their modulation. Materials and methods Two drug‐resistant cell lines, TCC8702/A1000 (adriamycin 1000 ng/mL) and TCC8803/A200 (adriamycin 200 ng/mL), were established after long‐term adriamycin treatment for at least 16 months. Their biological characteristics, including growth morphology, doubling time and cell cycle, were analysed. The drug‐resistance pattern to various anticancer drugs was measured using a microplate cytotoxicity assay. The modulation of drug sensitivity by calcium‐channel blockers and protein kinase C inhibitor was assessed among the different cancer cell lines. Results Both MDR sublines had lower growth rates, lower saturation densities and higher nuclear/cytoplasmic ratios than the parent cell lines. DNA staining and cell cycle analysis revealed that both TCC8702/A1000 and TCC8803/A200 cells had a decreased S‐phase fraction and the TCC8803/A200 cells a changed stem line; both sublines showed increased expression of membranous glycoprotein gp‐170. The cytoplasmic content of glutathione and glucose‐6‐phosphate dehydrogenase were not related to the MDR development in the sublines. The drug‐resistance index of TCC8702/A1000 to adriamycin was 121‐fold higher than the native cell line and TCC8803/A200 was 189‐fold higher. TCC8803/A200 also had a broader MDR to cisplatin, vinblastine and vincristine. Calcium‐channel blockers (verapamil, quinidine) and protein kinase C inhibitors (tamoxifen) inhibited gp‐170 activity and slowed the drug‐efflux pump, with the acquired‐MDR cells subsequently accumulating anticancer drugs. A calcium antagonist‐based combination of modulators all presented synergistic cytotoxic enhancement of the anticancer drugs. Parent TCC cell lines had a poorer response to modulator treatment than their MDR sublines. Conclusion Different MDR mechanisms and subsequent modulator responses exist between native and acquired drug resistance in TCC cells. Acquired MDR seems strongly related to increased gp‐170 expression and responds well to calcium antagonists. This phenomenon may be applicable in clinical conditions.

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