Double short-time exposure to pirarubicin produces higher cytotoxicity against T24 bladder cancer cells

This study was designed to determine the ideal manner (schedule and duration) of intravesical chemotherapy using pirarubicin (THP). At first, T-24 cancer cells were treated with 50, 100, 150, and 200 mu g/ml THP for 10, 30 and 60 min. Following the first exposure, at various intervals (3, 6, 12, and 24 h), a second exposure to THP was performed under the same condition in vitro. The cell viability was measured by XTT assay. Further, the cells were scanned with a laser scanning cytometer (LSC) and DNA histograms were analyzed to evaluate the cell-cycle components. A single exposure of T-24 cells to THP resulted in significantly higher inhibition of cell growth for 30 min with 100 mu g/ml and higher concentrations of THP; for example, the cell viability was reduced to 15, 2, and 0% by incubating cells with 100, 150, and 200 mu g/ml of THP, respectively, whereas it was 49% with 50 mu g/ml THP. Double exposure of T-24 cells to THP resulted in significantly higher inhibition of cell growth than single treatment at all intervals. LSC assay demonstrated a higher sub-G(1) peak after double treatment with THP when compared with that after a single treatment. Similar cytotoxic effects following double treatment with THP were observed on other bladder cancer cell lines (UMUC3, TCCSUP, 5637, and 253J cells) in vitro. In conclusion, the double short-term exposure to bladder cancer cells by THP has more remarkable cytotoxic effects than the single exposure in vitro.