title: Evaluation of copper-dependent proteasome-inhibitory and apoptosis-inducing activities of novel pyrrolidine dithiocarbamate analogues.
abstract: Apoptosis has a central role in the pathogenesis of many human diseases, one of which is cancer. One of the most important strategies to regulate apoptosis is via the ubiquitin-proteasome pathway. It has been shown that inhibition of proteasomal chymotrypsin-like activity is a strong apoptosis-inducing stimulus and that actively proliferating cancer cells are more sensitive to proteasome inhibitors than normal or untransformed cells. Dithioscarbamates are a class of metal-chelating compounds with various applications in medicine. We reported previously that certain members of dithiocarbamates, such as pyrrolidine dithiocarbamate (PDTC), diethyldithiocarbamate and disulfiram, are able to bind with tumor cellular copper, forming an active complex with proteasome-inhibitory, apoptosis-inducing and anti-cancer activities. In the current study, we synthesized eight PDTC analogues with substitutions made to the pyrrolidine ring and studied their structure-activity relationships. We found that substitution of the pyrrolidine ring with piperidine had almost no effect on their proteasome-inhibitory and anti-proliferative potencies in human breast cancer cells. However, after the pyrrolidine ring was substituted with morpholine, the activity of the mixtures slightly decreased but was completely lost when piperazine with the attached ethyl group was used for the substitution. This structure-activity relationship was confirmed by the results generated with the corresponding copper complexes. Our data further support the novel concept of using accumulated copper in human cancer cells as a selective approach for chemotherapy.
authors.affiliation: The Prevention Program, Barbara Ann Karmanos Cancer Institute, Department of Pathology, School of Medicine, Wayne State University, Detroit, MI 48201-2013, USA.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Yu
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Vesna
authors.initials: V
authors.lastname: Milacic
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Li
authors.forename: Qiuzhi Cindy
authors.initials: QC
authors.lastname: Cui
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Bing
authors.initials: B
authors.lastname: Yan
authors.forename: Q Ping
authors.initials: QP
authors.lastname: Dou
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003300:Copper / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015394:Molecular Structure; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011759:Pyrrolidines / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013859:Thiocarbamates / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D061988:Proteasome Inhibitors; D011759:Pyrrolidines; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid; D003300:Copper; D046988:Proteasome Endopeptidase Complex