Chemotherapeutic agents sensitize sarcoma cell lines to tumor necrosis factor‐related apoptosis‐inducing ligand‐induced caspase‐8 activation, apoptosis and loss of mitochondrial membrane potential

Abstract

Chemotherapeutic agents have been used for the treatment of patients with Osteosarcoma (0s). However, inherent or acquired resistance to these agents is a serious problem in the management of 0 s patients. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is considered to induce apoptosis in a variety of cancer cells but not normal cells. In the present study, we examined whether chemotherapeutic agents enhance TRAIL-induced apoptosis in the sarcoma cell lines MG-63 and SaOS-2. Pretreatment with sub-toxic or slightly toxic concentrations of chemotherapeutic agents (cis-diammine dichloroplatinum, CDDP and doxorubicin, DXR) sensitized both cell lines to TRAIL-induced apoptosis, as assessed by the propidium iodide or Annexin V-Cy5 staining method. These cell lines expressed death receptors TRAIL-receptor 1 (TRAIL-R1) and TRAIL-R2, which were unaltered by treatment with CDDP, as assessed by flow cytometry. The decoy receptors TRAIL-R3 and -R4 were barely detected in both cell lines. CDDP down-regulated c-FLIP, tending to lower the activation threshold required for TRAIL-induced caspase-8 activation. The CDDP-pretreated cells indeed demonstrated more increased TRAIL-mediated caspase-8 activation, loss of mitochondrial membrane potential (AY',,,), and apoptosis than untreated cells. Consequently, the activated caspase-8 might lead to either activation of effector caspases such as caspase-3 or loss in AY,,,. Both the increased caspase activation and mitochondrial dysfunction induced by combination of CDDP and TRAIL would contribute to enhanced apoptotic cell death. The results of the present study would be valuable for the design of novel treatment modalities for patients with 0 s .

Apoptosis induced by chemotherapeutic agents involves c‐Jun N‐terminal kinase activation in sarcoma cell lines

“…4,5 Therefore, new treatment modalities for sarcoma are urgently required. We have recently found that CDDP or DXR induces apoptosis in sarcoma cell lines MG-63 and SaOS-2, 21 as reported in other cell types. 30,31 However, molecular mechanisms of the apoptotic cell death induced by DNA-damaging agents are not completely known.…”

“…After exposure to 3 mg/mL CDDP or 3 mg/mL DXR for 24 h, the percentage of apoptotic cell death was determined using an Annexin V-Cy5 Apoptosis Detection Kit (BioVision, Inc., Mountain View, CA), as previously described, 21 which detects redistribution of intracellular phosphatidylserine on the extracellular surface. Briefly, cells (1 Â 10 5 /0.5 mL binding buffer) were incubated with 5 mL Cy5 conjugated Annexin V protein for 5 min, followed by flow cytometric analysis using a Nippon Becton Dickinson FACSCalibur cytometer (Tokyo, Japan).…”

Current status of tumor necrosis factor-related apoptosis-inducing ligand receptor (TRAIL-R) targeting cancer therapy

“…Synergistic interactions have been reported between TRAIL and a number of therapeutic agents, including IFN-alpha 35) , genotoxic agents such as doxorubicin, cisplatin, or etoposide [36][37][38][39][40][41] , irinotecan 24,29,34,[42][43][44] , gamma-radiation 45,46) , and cyclooxygenase-2 inhibitors 47) . Although the mechanisms of these synergies are not completely understood and are likely to vary between therapies, the following mechanisms have been suggested to influence the combination treatments synergies detected to date: receptor up-regulation, modulation of Bcl-2 family members, up-regulation of caspases, down-regulation of c-FLIP, which is an endogenous inhibitor of "extrinsic" caspase-8 activation, and inhibition of IAP family members, which inhibit "intrinsic" caspase-3 activation.…”

CYC1 Silencing Sensitizes Osteosarcoma Cells to TRAIL-Induced Apoptosis

“…TRAIL exhibits selective cytotoxicity towards cancer cells; and recombinant TRAIL and agonistic TRAIL-R1/R2 monoclonal antibodies are being developed as novel anti-cancer agents for a variety of malignancies [5]. However, many osteosarcomas are resistant to TRAIL, and induction of apoptosis requires combination treatment with other chemotherapeutic agents [6,7]. …”