Cool-1-mediated inhibition of c-Cbl modulates multiple critical properties of glioblastomas, including the ability to generate tumors in vivo.
We discovered that glioblastoma (GBM) cells use Cool-1/β-pix to inhibit normal activation of the c-Cbl ubiquitin ligase via the redox/Fyn/c-Cbl pathway and that c-Cbl inhibition is critical for GBM cell function. Restoring normal c-Cbl activity by Cool-1 knockdown in vitro reduced GBM cell division, almost eliminated generation of adhesion-independent spheroids, reduced the representation of cells expressing antigens thought to identify tumor initiating cells (TICs), reduced levels of several proteins of critical importance in TIC function (such as Notch-1 and Sox2), and increased sensitivity to BCNU (carmustine) and temozolomide (TMZ). In vivo, Cool-1 knockdown greatly suppressed the ability of GBM cells to generate tumors, an outcome that was c-Cbl dependent. In contrast, Cool-1 knockdown did not reduce division or increase BCNU or TMZ sensitivity in primary glial progenitor cells and Cool-1/c-Cbl complexes were not found in normal brain tissue. Our studies provide the first evidence that Cool-1 may be critical in the biology of human tumors, that suppression of c-Cbl by Cool-1 may be critical for generation of at least a subset of GBMs and offer a novel target that appears to be selectively necessary for TIC function and modulates chemoresistance in GBM cells. Targeting such proteins that inhibit c-Cbl offers potentially attractive opportunities for therapeutic development.
Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, New York, USA.
Brett M
BM
Stevens
Christopher J
CJ
Folts
Wanchang
W
Cui
Addie L
AL
Bardin
Kevin
K
Walter
Eleanor
E
Carson-Walter
Angelo
A
Vescovi
Mark
M
Noble
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D015153:Blotting, Western; D002330:Carmustine / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000494:pharmacology; D005434:Flow Cytometry; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism*; D034622:RNA Interference; D064067:Rho Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D018874:Spheroids, Cellular / Q000378:metabolism; D000077204:Temozolomide; D014183:Transplantation, Heterologous; D047368:Tumor Burden / Q000235:genetics; D014407:Tumor Cells, Cultured
C576606:ARHGEF7 protein, human; D018906:Antineoplastic Agents, Alkylating; D064067:Rho Guanine Nucleotide Exchange Factors; D003606:Dacarbazine; D050721:Proto-Oncogene Proteins c-cbl; C067419:CBL protein, human; D002330:Carmustine; D000077204:Temozolomide
Glioblastoma c-Cbl; Redox; Redox/Fyn/c-Cbl pathway; Tumor initiating cell; Tumor initiation