title: Resistance to Fas-mediated apoptosis in malignant tumours is rescued by KN-93 and cisplatin via downregulation of c-FLIP expression and phosphorylation.
abstract: 1. The purpose of the present study was to investigate the molecular mechanisms that control tumour cell resistance and to search for molecules that could overcome Fas ligand (FasL) or CH-11 resistance in certain tumours, including glioma and melanoma. 2. Twelve tumour cell lines were examined for their sensitivity to CH-11-induced apoptosis and then two of each of the CH-11-sensitive and -resistant tumour cell lines were analysed for Fas-mediated death-inducing signalling complex (DISC). The calmodulin kinase II (CaMKII) inhibitor KN-93 and the chemotherapeutic drug cisplatin were used to treat resistant cells; the effects of these two drugs on CH-11-resistant tumour cells were investigated. 3. In CH-11-sensitive tumour cells, apoptosis-initiating caspase 8 and caspase 10 were recruited to the DISC, where they became activated through autocatalytic cleavage, leading to apoptosis through cleavage of downstream substrates, such as caspase 3 and DNA fragmentation factor 45. 4. In CH-11-resistant cells, cellular Fas-associated death domain-like interleukin-1b-converting enzyme inhibitory protein (c-FLIP) proteins were recruited to the DISC, resulting in inhibition of caspase 8 and caspase 10 cleavage. The c-protein expression and phosphorylation of FLIP and CaMKII protein and enzyme activity were upregulated in resistant cells. Treatment of resistant cells with 100 micromol/L KN-93 and 10 microg/mL cisplatin downregulated c-FLIP expression, inhibited c-FLIP phosphorylation and rescued CH-11 sensitivity. 5. In conclusion, KN-93 and cisplatin inhibit c-FLIP protein expression and phosphorylation restores CH-11-induced apoptosis in tumour cells. tHe present study provides evidence for the use of a new combination therapeutic strategy in the treatment of malignant tumours.
authors.affiliation: Department of Pharmacology, Basic Medical College, Jilin University, Changchun, China.
authors.forename: Bao-Feng
authors.initials: BF
authors.lastname: Yang
authors.forename: Chang
authors.initials: C
authors.lastname: Xiao
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Shi-Jie
authors.initials: SJ
authors.lastname: Yang
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001596:Benzylamines / Q000494:pharmacology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors; D053455:Caspase 10 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D053222:Fas Ligand Protein / Q000378:metabolism*; D005910:Glioma / Q000473:pathology; D006801:Humans; D008545:Melanoma / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology*; D000096926:Benzenesulfonamides
chemical_list: D000906:Antibodies; D000970:Antineoplastic Agents; D001596:Benzylamines; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D053455:Caspase 10; D053181:Caspase 8; D002945:Cisplatin; D053222:Fas Ligand Protein; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; C506386:CFLAR protein, human; C481004:CH-11 anti-fas antibody, human; C072105:KN 93; D000096926:Benzenesulfonamides