Tumstatin induces apoptosis and stimulates phosphorylation of p65NF-κB in human osteoblastic osteosarcoma Saos-2 cells.
The present study was aimed to investigate the effect of tumstatin on inhibition of proliferation and induction of apoptosis in Saos-2 human osteosarcoma cells and to understand the mechanism involved. Inhibition of cell proliferation was analyzed by MTT assay and induction of apoptosis through nuclear fragmentation assay. Viability of Saos-2 cells was reduced to 19% on treatment with 25 µM concentration of tumstatin after 48 h. Presence of characteristic apoptotic nuclei, rounded cell shape and shrunken size were caused by tumstatin treatment at 25 µM concentration. The level of mRNA corresponding to PTEN, FasR and FasL was increased significantly in tumstatin treated Saos-2 cells compared to untreated control. Investigation of the mechanism revealed NF-κB activation by phosphorylation on serine 536. The activated NF-κB was translocated into the nucleus from the cytoplasm on treatment with tumstatin. Degradation of the IκBα by tumstatin was found to be much slower compared to that induced by treatment with TNF-α. Thus, tumstatin inhibits proliferation and induces apoptosis in Saos-2 cells through activation of NF-κB and its translocation to the nucleus. Therefore, tumstatin can play an important role in the treatment of osteosarcoma.
Department of Orthopaedics, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China.
Yang
Y
Wang
Department of Orthopaedics, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China.
Ruo-Feng
RF
Yin
Department of Orthopaedics, Daqing Oilfields general Hospital, Daqing, Heilongjiang 163000, P.R. China.
Jia-Song
JS
Teng
D017209:Apoptosis / Q000187:drug effects*; D001324:Autoantigens / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D024141:Collagen Type IV / Q000494:pharmacology*; D006801:Humans; D012516:Osteosarcoma / Q000188:drug therapy* / Q000473:pathology; D051059:PTEN Phosphohydrolase / Q000235:genetics; D010766:Phosphorylation; D051996:Transcription Factor RelA / Q000378:metabolism*
D001324:Autoantigens; D024141:Collagen Type IV; D051996:Transcription Factor RelA; C057112:type IV collagen alpha3 chain; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human