Selective cyclooxygenase-2 inhibitors inhibit growth and induce apoptosis of bladder cancer.

Selective COX-2 inhibitors such as celecoxib and NS-398 are being evaluated as chemopreventive and therapeutic agents for bladder and other cancers. We investigated the effects of these nonsteroidal anti-inflammatory agents on a panel of bladder cancer cell lines, and assessed their effects on anchorage-dependent and -independent growth, cell cycle, apoptosis and morphology. The human bladder cancer cell lines UM-UC-1, -3, and -6 were assayed for COX-2 expression by Western analysis using a monoclonal antibody to COX-2. UM-UC-1, -3, and -6 cells were grown in the presence of increasing concentrations of NS-398 and celecoxib, and cell growth was quantitated over 7 days by crystal violet elution. The cell lines were treated with NS-398 and celecoxib for 48 h and analyzed by flow cytometry with propidium iodide staining and Br-dUTP staining for apoptosis. Anchorage-independent growth was assessed using an agarose growth assay. Western analysis demonstrated that COX-2 expression in UM-UC-1, -6, and -3 was high, low, and undetectable, respectively. NS-398 and celecoxib produced dose-dependent growth inhibition of UM-UC-1 and -6. Both NS-398 and celecoxib also inhibited anchorage-dependent and -independent growth of UM-UC-3 in a dose-dependent fashion, despite the low basal expression of COX-2 in this cell line. Cell cycle analyses of UM-UC-1 and -6 revealed a 50% reduction in S-phase in the presence of 100 microM NS-398 whereas a smaller reduction in S-phase was noted in UM-UC-3 cells. Furthermore, treatment with 100 microM celecoxib resulted in significant apoptosis in all three cell lines, which was associated with downregulation of Bcl-2. COX-2 selective inhibitors NS-398 and celecoxib produced dose-dependent growth inhibition of bladder cancer cells associated with a significant reduction in S-phase. Induction of apoptosis in all three cell lines by celecoxib was associated with downregulation of Bcl-2. These changes occur independently of COX-2 expression levels suggesting the presence of a COX-2 independent pathway.

Effective cytotoxicity against human leukemias and chemotherapy-resistant leukemia cell lines by N-N-dimethylsphingosine.

We evaluated the cytotoxicity of dimethylsphingosine (DMS) against four human leukemia cell lines: two acute (HL60 and a multi-drug resistance MDR-positive derivative HL60-dox) and two blast crisis chronic myelogenous leukemias (JFP1, from a treatment refractory patient and K562), and against blasts isolated from 11 leukemia patients. Cell line viability decreased proportionally to DMS concentration and treatment time (P<0.001). HL60-dox and JFP1 were the most sensitive, indicating DMS efficacy against human leukemia MDR. Importantly, leukemia samples showed a similar sensitivity to DMS as that of the cell lines, firstly demonstrating PKC-independent sphingolipid activity against fresh human tumor specimens. DMS-based chemotherapy may improve leukemia treatment.

Dexrazoxane in combination with anthracyclines lead to a synergistic cytotoxic response in acute myelogenous leukemia cell lines.

In an attempt to improve current therapeutic strategies for acute myelogenous leukemia (AML), we studied the effects of a commercially available drug, dexrazoxane (DEX), which protects against anthracycline-induced cardiotoxicity. The rationale was that DEX would permit higher doses of cardiotoxic drugs to be given. The drug itself may have therapeutic potential as well. Finally, there are concerns that the drug may, as a protective agent, diminish the effectiveness of various chemotherapeutics. To help resolve the question about potential drug antagonism, we undertook a series of in vitro analyses of DEX and various combinations with anthracyclines and other agents. Colony-forming assays were used to evaluate stem-cell renewal of myeloid cells in vitro, and median-effect analysis was used to evaluate antagonism, synergism, and additivity. The anthracyclines doxorubicin, daunorubicin, and idarubicin were individually combined with DEX to study in vitro effects in leukemic myeloid cell lines. In the hope, we could extend the findings to non-anthracyclines, etoposide and cytosine arabinoside were also evaluated in combination with DEX using the same in vitro model and method. We found that the effects of DEX in combination with any of the anthracyclines were schedule dependent. The antitumor effect was greater for each combination than for any anthracycline alone except when DEX was administered 24h before doxorubicin or daunorubicin. These data were corroborated through median-effect analysis. Etoposide in combination with DEX was synergistic for all combinations and schedules, and the combination of cytosine arabinoside and DEX was effective depending on the schedule used. DEX appears to be a promising drug in the treatment of AML and warrants further clinical study involving novel drug combinations.

Dexrazoxane's protection of jejunal crypt cells in the jejunum of C3Hf/Kam mice from doxorubicin-induced toxicity.

Dexrazoxane (DEX) is used clinically to reduce doxorubicin-induced cardiotoxicity. Because DEX inhibits anthracycline-induced toxicity, we set out to investigate DEX's ability to reduce the incidence and severity of gastrointestinal toxicity associated with anthracycline administration in C3Hf/Kam mice. Doxorubicin and idarubicin, two commonly used anthracyclines, were each examined in combination with DEX. A jejunal crypt survival assay demonstrated that DEX increased crypt survival from 40% (doxorubicin 22.5 mg/kg) to 63% at a DEX/doxorubucin dose ratio of 10:1 ( P<0.05). When doxorubicin was increased to a dose of 27.5 mg/kg, crypt survival increased from 18% to 40% at a DEX:Dox ratio of 5:1 ( P<0.05). At ratios of 10:1 and 20:1, DEX had no protective effect on idarubicin-induced crypt cell toxicity. Our findings support the use of DEX to prevent or ameliorate mucositis in patients receiving anthracycline-based therapy and the use of DEX with high-dose doxorubicin to treat refractory disease.