Two Cancer-Suppressing Proteins Identified in Lab of Israeli Nobel Laureate in Chemistry

A new study by researchers at the Technion-Israel Institute of Technology in Haifa, Israel could hold a key to control cancer cell growth and development. In a paper publishedin the April 9, 2015 issue of Cell, the team reports on the discovery of two cancer-suppressing proteins (KPC-1 and p50). The article is titled “KPC1-Mediated Ubiquitination and Proteasomal Processing of NF-κB1 p105 to p50 Restricts Tumor Growth.” The research was conducted in the laboratory of Distinguished Professor Aaron Ciechanover (photo), of the Technion Rappaport Faculty of Medicine. Dr. Ciechanover shared the 2004 Nobel Prize in Chemistry for the “discovery of ubiquitin-mediated protein degradation.” The team was led by Research Associate Dr. Yelena Kravtsova-Ivantsiv and included additional research students and colleagues, as well as physicians from the Rambam, Carmel, and Hadassah Medical Centers, who are studying tumors and their treatment. KPC1 (Kip1 ubiquitylation-promoting complex 1) is the catalytic subunit of the ubiquitin ligase KPC, which regulates the degradation of the cyclin-dependent kinase inhibitor p27(kip1) at the G1 phase of the cell cycle. The KPC1 pathway is vital in the life of the cell, which is responsible for the degradation of defective proteins that could damage the cell if not removed. The ubiquitin system tags these proteins and sends them for destruction in the cellular complex known as the proteasome. The system also removes functional and healthy proteins that are not needed anymore, thereby regulating the processes that these proteins control. Usually, the proteins that reach the proteasome are completely broken down, but there are some exceptions, and the current line of research examined p105, a long precursor of a key regulator in the cell called NF-kB.
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