Anticancer drug activity in human bladder tumor cell lines

Exposure time versus cytotoxicity for anticancer agents

PURPOSE

Time is a critical factor in drug action. The duration of inhibition of the target or residence time of the drug molecule on the target often guides drug scheduling.

METHODS

The effects of time on the concentration-dependent cytotoxicity of approved and investigational agents [300 compounds] were examined in the NCI60 cell line panel in 2D at 2, 3, 7 and in 3D 11 days.

RESULTS

There was a moderate positive linear relationship between data from the 2-day NCI60 screen and the 3-, 7- and 11-day and a strong positive linear relationship between 3-, 7- and 11-day luminescence screen IC50s by Pearson correlation analysis. Cell growth inhibition by agents selective for a specific cell cycle phase plateaued when susceptible cells were growth inhibited or killed. As time increased the depth of cell growth inhibition increased without change in the IC50. DNA interactive agents had decreasing IC50s with increasing exposure time. Epigenetic agents required longer exposure times; several were only cytotoxic after 11 days' exposure. For HDAC inhibitors, time had little or no effect on concentration response. There were potency differences amongst the three BET bromodomain inhibitors tested, and an exposure duration effect. The PARP inhibitors, rucaparib, niraparib, and veliparib reached IC50s < 10 μM in some cell lines after 11 days.

CONCLUSIONS

The results suggest that variations in compound exposure time may reflect either mechanism of action or compound chemical half-life. The activity of slow-acting compounds may optimally be assessed in spheroid models that can be monitored over prolonged incubation times.

Ling-Zhi polysaccharides potentiate cytotoxic effects of anticancer drugs against drug-resistant urothelial carcinoma cells

The combined effects of ling-zhi polysaccharide fraction 3 (LZP-F3) and anticancer drugs (cisplatin and arsenic trioxide) were examined in three human urothelial carcinoma (UC) cells (parental, NTUB1; cisplatin-resistant, N/P(14); and arsenic-resistant, N/As(0.5)). MTT assay and median-effect analysis revealed that LZP-F3 could profoundly reverse the chemosensitivity of N/P(14) and N/As(0.5) to cisplatin and arsenic, respectively, in a dose-dependent manner, which involved activation of p38 and down-regulation of Akt and XPA. A dose of 10 mug/mL of LZP-F3 induced significant G1 arrest in N/P(14) and N/As(0.5) cells by flow cytometry, which may be mediated by the induction of p21(WAF1/CIP1). The combination of LZP-F3 and arsenic trioxide produced a significant synergistic growth inhibition of NTUB1 and N/As(0.5) cells. Similar results were also found in N/P(14) cells. These molecular events of combined effects involved significant and earlier induction of Fas, caspase 3 and 8 activation, Bax and Bad up-regulation, Bcl-2 and Bcl-x(L) down-regulatuion, and cytochrome c release.

Taxol and taxotere in bladder cancer: in vitro activity and urine stability

In this study the antimicrotubular agents taxol, taxotere, and vinblastine were compared for their ability to inhibit the clonal growth of human bladder tumor cell lines using a soft-agar clonogenic assay. The stability of taxol and taxotere was evaluated by high-performance liquid chromatography over a range of pH in human urine. Both taxol and taxotere were shown to maximally inhibit the clonal growth of human bladder cell lines within 1 h of drug incubation. The most active agent in the panel of tumor lines was taxotere, with 6 of 12 lines being sensitive to the agent at 0.01 microM and all cell lines being sensitive at 0.1 microM. Taxol was active in 1 of 12 lines at 0.01 microM and in 11 of 12 at 0.1 microM. Only 2 of 12 cell lines were sensitive to vinblastine over the 0.01- to 0.1-microM dose range. Taxol and taxotere were found to be stable in human urine for 4 h over a pH range of 5-7. At least 85% of both drugs were present during this period of drug incubation. Our findings suggest that both taxol and taxotere may be clinically useful agents for systemic and intravesical use in bladder cancer.

Multi-drug resistance of a doxorubicin-resistant bladder cancer cell line

A bladder tumor cell line resistant to doxorubicin (MGH-U1R) has been established previously by culturing a human transitional cell carcinoma cell line (MGH-U1) in increasing concentrations of the drug. MGH-U1R is 40 times more resistant to doxorubicin than MGH-U1. In the present study, MGH-U1R was evaluated for its multi-drug resistance or pleiotropism by testing against other chemotherapeutic agents. MGH-U1R was found to be 188 times more resistant to vinblastine and 13 times more resistant to etoposide than MGH-U1, while remained sensitive to bleomycin. Taken together with earlier evidence that the resistance of MGH-U1R to doxorubicin can be reversed by a calcium-channel blocker verapamil, and the measured over-expression of the mdr1 gene in these cells, MGH-U1R has the characteristic multiple drug resistance properties similar to other established doxorubicin resistant carcinoma cell lines. MGH-U1R may be a useful model for the development of strategies in overcoming drug-resistance in the treatment of transitional cell carcinoma.

Clonal growth requirements of human bladder tumor cell lines

We have serially investigated the role of nutrients and growth factors for their ability to support the clonal growth of human bladder tumor cell lines. Five established human bladder tumor cell lines were selected for study of their requirements for clonogenic growth in semisolid cultures. We identified an "optimal medium" to be Alpha MEM medium, 15% horse serum, five micrograms/ml. of transferrin, five micrograms/ml. of insulin and 30 ng./ml. of epidermal growth factor. The "optimal assay" enhanced the growth of human bladder tumor cell lines 2.5 times compared to the standard clonogenic assay. The resulting medium is less complicated to maintain, less expensive and supports the growth of human bladder tumor cell lines better than the standard clonogenic assay.

Establishment and characterization of a doxorubicin-resistant human bladder cancer cell line (MGH-U1R)

A doxorubicin-resistant bladder cancer cell line has been established. This was accomplished by exposing an established human bladder tumor cell line, MGH-U1, to progressively higher concentrations of doxorubicin over a period of 12 months. The resistant cells, MGH-U1R, are nine times more resistant to doxorubicin and 30 times more resistant to daunorubicin than the parent cells. The MGH-U1R and the MGH-U1 cells have identical isozyme phenotypes. Compared to the parent cells, the resistant cells have a slower growth rate, lower confluent density, are more heterogeneous morphologically, and exhibit more chromosomal aberrations and rearrangements. The resistant cells may now be used as an experimental system for the search of means to overcome drug resistance in human bladder cancer.