ABSTRACT
BACKGROUND: Tumor necrosis factor related apoptosis-inducing ligand/Apo2 ligand (TRAIL/Apo-2L) is a novel anticancer agent, capable of inducing apoptosis preferentially in tumor and transformed cells. TRAIL-R1/death receptor (DR)4 and TRAIL-R2/DR5 are members of the tumor necrosis factor (TNF) receptor family, and can be activated by the TRAIL. We examined the clinical potential of chemotherapeutic drugs and TRAIL for the treatment of prostate cancer. METHODS: Prostate and bladder cancer cells were exposed to chemotherapeutic drugs (paclitaxel, vincristine, vinblastine, etoposide, doxorubicin, and camptothecin) and TRAIL. Cell viability was measured by sodium 3'[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis (4-methoxy-6-nitro) assay; expressions of death receptors and Bcl-2 family members were measured by Western blotting, ELISA and ribonuclease protection assay. PC-3 tumor cells xenografted athymic nude mice were exposed to chemotherapeutic drugs and TRAIL, either alone or in combination, to measure tumor growth and survival of mice. Apoptosis was measured by annexin V-FITC/propidium iodide staining, and terminal deoxynucleotidyltransferase-mediated nick end labeling assay. Caspase-3 activity was measured by the Western blotting and immunohistochemistry. RESULTS: TRAIL induced apoptosis with varying sensitivity. Chemotherapeutic drugs (paclitaxel, vincristine, vinblastine, etoposide, doxorubicin, and camptothecin) significantly augmented TRAIL-induced apoptosis in cancer cells through up-regulation of DR4, DR5, Bax, and Bak, and induction of caspase activation. Mitochondrial pathway enhanced the synergistic interactions between drugs and TRAIL. The sequential treatment of mice with chemotherapeutic drugs followed by TRAIL induced caspase-3 activity, and apoptosis, inhibited angiogenesis, completely eradicated the established tumors, and enhanced survival of mice. CONCLUSIONS: Chemotherapeutic drugs can be used to enhance the therapeutic potential of TRAIL in prostate cancer.
Subject(s)
Antineoplastic Agents/pharmacology , Membrane Glycoproteins/pharmacology , Prostatic Neoplasms/drug therapy , Tumor Necrosis Factor-alpha/pharmacology , Androgens/metabolism , Animals , Apoptosis/drug effects , Apoptosis Regulatory Proteins , Caspase 3 , Caspases/metabolism , Drug Synergism , Humans , In Vitro Techniques , Male , Mice , Mice, Inbred BALB C , Mice, Nude , Mitochondria/drug effects , Mitochondria/physiology , Neovascularization, Pathologic/drug therapy , Neovascularization, Pathologic/mortality , Prostatic Neoplasms/mortality , Proto-Oncogene Proteins c-bcl-2/metabolism , Receptors, TNF-Related Apoptosis-Inducing Ligand , Receptors, Tumor Necrosis Factor/metabolism , Survival Rate , TNF-Related Apoptosis-Inducing Ligand , Urinary Bladder NeoplasmsABSTRACT
Tumor necrosis factor-related apoptosis-inducing-ligand (TRAIL/Apo-2 ligand) induces apoptosis in the majority of cancer cells without appreciable effect in normal cells. Here, we report the effects of TRAIL on apoptosis in several human breast cancer cell lines, primary memory epithelial cells, and immortalized nontransformed cell lines, and we examine whether chemotherapeutic agents augment TRAIL-induced cytotoxicity in breast cancer cells in vitro and in vivo. TRAIL induced apoptosis with different sensitivities, and the majority of cancer cell lines were resistant to TRAIL. The chemotherapeutic drugs (paclitaxel, vincristine, vinblastine, etoposide, camptothecin, and Adriamycin) induced death receptors (DRs) TRAIL receptor 1/DR4 and TRAIL receptor 2/DR5, and successive treatment with TRAIL resulted in apoptosis of both TRAIL-sensitive and -resistant cells. Actinomycin D sensitized TRAIL-resistant cells through up-regulation of caspases (caspase-3, -9, and -8). TRAIL induces apoptosis in Adriamycin-resistant MCF7 cells already expressing high levels of death receptors DR4 and DR5. The pretreatment of breast cancer cells with chemotherapeutic drugs followed by TRAIL reversed their resistance by triggering caspase-3, -9, and -8 activation. The sequential treatment of nude mice with chemotherapeutic drugs followed by TRAIL induced caspase-3 activity and apoptosis in xenografted tumors. Complete eradication of established tumors and survival of mice were achieved without detectable toxicity. Thus, the sequential administration of chemotherapeutic drugs followed by TRAIL may be used as a new therapeutic approach for cancer therapy.
