The researchers reported their findings, "A small molecule based on the pRb2/p130 spacer domain leads to inhibition of cdk2 activity, cell cycle arrest and tumor growth reduction in vivo," in the March 22 issue of the journal Oncogene (http://www.nature.com/onc). Rb2/p130 was discovered in the early 1990s by Antonio Giordano, director of the Sbarro Institute (http://www.shro.org) and the Center for Biotechnology in Temple's College of Science and Technology, who headed the study.
The researchers discovered that within Rb2/p130's spacer domain--a sequence of 212 amino acids located in the pocket or middle section of the gene--was a small portion that resembled an amino-acidic sequence contained in the protein p21, which acts as a cdk (cyclin dependent kinase) inhibitor. Cdks play a critical role in cell cycle regulation.
"What we tested was the ability of the Rb2/p130 spacer region to inhibit the kinase activity of cdk2, which is the same kinase p21 inhibits," said Giordano, one of the study's lead authors. "And to our surprise, it happened." The researchers then set about trying to reduce the spacer domain's 212 amino acids down to the smallest sequence that would still produce the same functionality as p21, explained Giordano.
"We thought we could narrow down the spacer region that contains the protein-like motif to a small portion that could be delivered as a small molecule or peptide," Giordano said.
They discovered a 39 amino-acid-long sequence, which they named Spa310. The molecule that was synthetically produced in the laboratory