Inhibiting Hdm2 and ubiquitin-activating enzyme: targeting the ubiquitin conjugating system in cancer.

The ubiquitin conjugating system represents a rich source of potential molecular targets for cancer and other diseases. One target of great interest is the RING finger ubiquitin ligase (E3) Hdm2/Mdm2, which is frequently overexpressed in cancer and is a critical E3 for the tumor suppressor p53. For those 50% of tumors that express wild-type p53, agents that inhibit Hdm2 have great potential clinical utility.

Identification of inhibitors for MDM2 ubiquitin ligase activity from natural product extracts by a novel high-throughput electrochemiluminescent screen.

High-throughput screening technologies have revolutionized the manner in which potential therapeutics are identified. Although they are the source of lead compounds for ~65% of anticancer and antimicrobial drugs approved by the Food and Drug Administration between 1981 and 2002, natural products have largely been excluded from modern screening programs. This is due, at least in part, to the inherent difficulties in testing complex extract mixtures, which often contain nuisance compounds, in modern bioassay systems.

Cdc42 regulates E-cadherin ubiquitination and degradation through an epidermal growth factor receptor to Src-mediated pathway.

E-cadherins play an essential role in maintaining epithelial polarity by forming Ca2+-dependent adherens junctions between epithelial cells. Here, we report that Ca2+ depletion induces E-cadherin ubiquitination and lysosomal degradation and that Cdc42 plays an important role in regulating this process. We demonstrate that Ca2+ depletion induces activation of Cdc42.