Bortezomib

Novel treatment modalities are urgently required for androgen-independent prostate cancer. In order to develop an alternative treatment for prostate cancer, the cytotoxic effects of the 26S proteasome inhibitor bortezomib, either alone or in combination with the two commonly used chemotherapeutic agents irinotecan and etoposide, on the human prostate cancer cell line PC-3 were evaluated in the present study. The PC-3 cell line was maintained in Dulbecco's modified Eagle's medium with 10% fetal bovine serum and treated with various doses of bortezomib, irinotecan, etoposide or their combinations. The growth inhibitory and cytotoxic effects were determined by water-soluble tetrazolium (WST)-1 assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay or iCELLigence system. The combination index values were determined by the Chou-Talalay method. The half maximal inhibitory concentration (IC50) value of bortezomib on the PC-3 cell line was determined to be 53.

The abundance of the BCR/ABL protein critically contributes to CML pathogenesis and drug resistance. However, understanding of molecular mechanisms underlying BCR/ABL gene regulation remains incomplete. While BCR/ABL kinase inhibitors have shown unprecedented efficacy in the clinic, most patients relapse. In this study, we demonstrated that the Sp1 oncogene functions as a positive regulator for BCR/ABL expression. Inactivation of Sp1 by genetic and pharmacological approaches abrogated BCR/ABL expression, leading to suppression of BCR/ABL kinase signaling and CML cell proliferation. Because of potential adverse side effects of bortezomib (BORT) in imatinib-refractory CML patients, we designed a transferrin (Tf)-targeted liposomal formulation (Tf-L-BORT) for BORT delivery. Cellular uptake assays showed that BORT was efficiently delivered into K562 cells, with the highest efficacy obtained in Tf-targeted group. After administered into mice, L-BORT exhibited slower clearance with less toxicity compared to free BORT.

Novel treatment modalities are urgently required for androgen-independent prostate cancer. In order to develop an alternative treatment for prostate cancer, the cytotoxic effects of the 26S proteasome inhibitor bortezomib, either alone or in combination with the two commonly used chemotherapeutic agents irinotecan and etoposide, on the human prostate cancer cell line PC-3 were evaluated in the present study. The PC-3 cell line was maintained in Dulbecco's modified Eagle's medium with 10% fetal bovine serum and treated with various doses of bortezomib, irinotecan, etoposide or their combinations. The growth inhibitory and cytotoxic effects were determined by water-soluble tetrazolium (WST)-1 assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay or iCELLigence system. The combination index values were determined by the Chou-Talalay method. The half maximal inhibitory concentration (IC50) value of bortezomib on the PC-3 cell line was determined to be 53.