The role of cbl family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells.
BACKGROUND. Exosomes are nanometer-sized vesicles with immunomodulatory functions, which are released by a diverse range of living cells. Although recent studies have shown that tumor-derived exosomes can suppress the function of T cells, the molecular mechanisms are not well understood. In the present study, we investigated the role of the Casitas B lineage lymphoma (cbl) family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells. MATERIALS AND METHODS. By serial centrifugation and sucrose gradient ultracentrifugation, we isolated and purified the exosomes from gastric cancer SGC7901 cells, and identified them by electron microscopy and Western blotting. Cell apoptosis was detected using propidium iodide staining. Western blotting and RT-PCR was exploited to evaluate the expression of proteins and mRNA, respectively. RESULTS. Gastric cancer exosomes induced Jurkat T cell apoptosis in a time- and dose-dependent manner and activated caspases 3, 8 and 9. The expression of Cbl-b and c-Cbl was up-regulated during exosome-induced apoptosis of cells. Meanwhile, exosomes induced ubiquitination of the p85 subunit of phosphoinositide 3-kinase (PI3K) and reduced downstream Akt activity. Inhibition of proteasome led to partial restoration of Akt activity and cell apoptosis. DISCUSSION AND CONCLUSIONS. The Cbl family of ubiquitin ligases might be involved in regulation of exosome-induced apoptosis of Jurkat T cells by increasing PI3K proteasome degradation, inactivation of PI3K/Akt signaling, thus mediating some effects of caspase activation.
Qu
Jing-Lei
JL
Department of Medical Oncology, The First Hospital, China Medical University, NO.155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning Province, China.
Qu
Xiu-Juan
XJ
Qu
Jing-Lei
JL
Qu
Xiu-Juan
XJ
Zhao
Ming-Fang
MF
Teng
Yue-E
YE
Zhang
Ye
Y
Hou
Ke-Zuo
KZ
Jiang
You-Hong
YH
Yang
Xiang-Hong
XH
Liu
Yun-Peng
YP
D000230:Adenocarcinoma; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D055354:Exosomes / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019169:Jurkat Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000201:enzymology* / Q000276:immunology* / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism / Q000502:physiology*; D015854:Up-Regulation
D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D046988:Proteasome Endopeptidase Complex; C067419:CBL protein, human