Degrasyn activates proteasomal-dependent degradation of c-Myc.
c-Myc is a highly unstable transcription factor whose deregulation and increased expression are associated with cancer. Degrasyn, a small synthetic molecule, induces rapid degradation of c-Myc protein in MM-1 multiple myeloma and other tumor cell lines. Destruction of c-Myc by degrasyn requires the presence of a region of c-Myc between amino acid residues 316 and 378 that has not previously been associated with c-Myc stability. Degrasyn-induced degradation of c-Myc depends on proteasomes but is independent of the degron regions previously shown to be important for ubiquitin-mediated targeting and proteasomal destruction of the protein. Degrasyn-dependent c-Myc proteolysis is not mediated by any previously identified c-Myc regulatory mechanism, does not require new protein synthesis, and does not depend on the nuclear localization of c-Myc. Degrasyn reduced c-Myc levels in A375 melanoma cells and in A375 tumors in nude mice, and this activity correlated with tumor growth inhibition. Together, these results suggest that degrasyn reduces the stability of c-Myc in vitro and in vivo through a unique signaling process that uses c-Myc domains not previously associated with c-Myc regulation.
Bartholomeusz
Geoffrey
G
Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Talpaz
Moshe
M
Bornmann
William
W
Kong
Ling-Yuan
LY
Donato
Nicholas J
NJ
D000818:Animals; D045744:Cell Line, Tumor; D003487:Cyanoacrylates; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008545:Melanoma / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009101:Multiple Myeloma / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology*; D010449:Peptide Mapping; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
D003487:Cyanoacrylates; C489427:MYC protein, human; D009570:Nitriles; D016271:Proto-Oncogene Proteins c-myc; D011725:Pyridines; C519751:degrasyn; D046988:Proteasome Endopeptidase Complex