Abstract
Renal cell carcinomia (RCC) is one of the ten most common and malignant tumor diseases worldwide. At current state, RCC represents 86% of all malignant kidney diseases. As medical research shows RCC is usually chemoresistant. Over the last decades the efflux transporters of the ATP- binding cassette (ABC)- superfamily have intensively been studied. It is proved that these proteins are related to the chemoresistance of cells. In renal cancer cells the influx transporters of the solute carrier (SLC) family are not well understood. SLC transporters are shown to be involved in absorption, distribution and metabolism of endogens and exogenous substrates, including cytostatics. The expression of SLC transporters in renal cancer cells can be used to increase the intercellular accumulation of antineoplastic compounds and to improve the chemosensitivity of RCC cell lines. In addition it is important to find out possible factors, which influence the expression of transport proteins and further to analyse the interactions of antineoplastic compounds with transport proteins for specific cancer chemotherapy. This dissertation focuses on the investigation of selected human efflux transporters (members of the ABC family: MDR1 and MRP2) and influx transporters (SLC transporters: organic anion transporters OAT1, OAT3, OAT4, OAT10; organic cation transporters OCT1, OCT2 and OCT3); their expression in the RCC cell lines (786-O, ACHN, LN78 and RCCNG1) as well as their role in chemosensitivity of these carcinoma cells. The main aim of this thesis was to elucidate the effect of the transcription factor B-cell lymphoma 6 (BCL6) on the expression of renal efflux and influx transporters in selected RCC cell lines. Further it was intended to detect if, due to this expression, the chemosensitivity of the RCC cell lines could be increased. The mRNA levels of the selected transporters in BCL6-transfected RCC cell lines were measured by quantitative real-time PCR. This study revealed that the transient transfection of BCL6 into RCC cell lines had no influence on the expression level of MDR1, MRP2, OATs and OCTs. There was just a small decrease in the expression level of OCT1-mRNA in the RCC cell line ACHN. The protein expression of BCL6 in RCC cell lines was investigated by using immunofluorescense microscopy. BCL6 transfected RCCNG1 cells expressed BCL6 protein in their cell nuclei (approximately 6,5%). However BCL6 protein was not expressed in BCL6 transfected cell lines 786-O, ACHN and LN78 (< 1 %). The cytostatic effects of the antineoplastics 5-Fluorouracil (5-FU), Irinotecan and Oxaliplatin on BCL6 transfected RCCNG1 cells and control cells was examined. Nevertheless, after incubation with 5-FU (1 µM, 10 µM, 100 µM) for 16 hours, no apoptosis was occured. Further examinations displayed that neither the same concentrations of Irinotecan nor Oxaliplatin induced apoptosis in RCCNG1 cells. Thus it is proved that BCL6 does not enhance chemosensitivity of RCCNG1 cells to the antineoplastics 5-FU, Irinotecan and Oxaliplatin. These results demonstrate that the transcription factor BCL6 has no influence on the investigated protein expression of efflux and influx transporters in the RCC cell lines 786-O, ACHN, LN78 and RCCNG1, which shows no enhancement in chemosensitivity of RCCNG1 cells. This might be important for further research strategies.
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