DEP domain containing mammalian target of rapamycin (mTOR)-interacting protein (DEPTOR) is an mTOR binding protein that is overexpressed in RPMI-8226 human multiple myeloma cells, and plays an important role in maintaining cell survival. However, knowledge on the effects of DEPTOR knockdown
on the biological functions of RPMI8226 human multiple myeloma cells, is limited. This study aimed to determine the role of DEPTOR in the proliferation, apoptosis and autophagy in these cells and to elucidate the mechanisms by which DEPTOR contributes to the chemosensitivity of myeloma cells.
RNA interference was used to reduce the expression of DEPTOR. Cytotoxicity was evaluated by MTT assay. Apoptosis was examined by flow cytometry. DEPTOR mRNA and protein expression in RPMI8226 cells treated with DEPTOR-specific short hairpin RNA (shRNA) was evaluated by RT-PCR, quantitative
PCR and western blot analysis. The expression of apoptosisassociated proteins, autophagyassociated proteins, and the activation of the phosphoinositide 3kinase (PI3K)/Akt signaling pathway were detected by western blot analysis. Autophagy was also measured by transmission electron microscopy
and monodansylcadaverine (MDC). In this study, RPMI-8226 cells were transfected with the DEPTOR-specific shRNA, which resulted in the significant inhibition of the transcription and expression of DEPTOR. The downregulation of DEPTOR inhibited proliferation, enhanced the doxorubicininduced
growth inhibitory effects on RPMI-8226 cells, and increased the expression of cleaved caspase3 and cleaved poly(ADP-ribose) polymerase (PARP). Moreover, the downregulation of DEPTOR suppressed autophagy and inhibited the activation of the PI3K/Akt signaling in RPMI8226 cells. In conclusion,
our data demonstrated that the downregulation of DEPTOR induces apoptosis, increases chemosensitivity to doxorubicin, and suppresses autophagy and the activation of the PI3K/Akt signaling pathway in RPMI8226 human multiple myeloma cells.
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Document Type: Research Article
Department of Hematology and Rheumatology, The First Clinical Medical College of Fujian Medical University, Fuzhou, Fujian, P.R. China
Laboratory of Electron Microscopy, School of Basic Medical Sciences of Fujian Medical University, Fuzhou, Fujian, P.R. China
Publication date: January 1, 2013
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The International Journal of Molecular Medicine is a monthly, peer-reviewed journal devoted to the publication of high quality studies related to the molecular mechanisms of human disease. The journal welcomes research on all aspects of molecular and clinical research, ranging from biochemistry to immunology, pathology, genetics, human genomics, microbiology, molecular pathogenesis, molecular cardiology, molecular surgery and molecular psychology.
The International Journal of Molecular Medicine aims to provide an insight for researchers within the community in regard to developing molecular tools and identifying molecular targets for the diagnosis and treatment of a diverse number of human diseases.
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