Cancer cell division and replication is rife with problems.Whereas normal cells will stop division if they detect DNA damage, or willundergo apoptosis, or cell death, cancer cells continue to divide andreplicate, a condition known as hyperplasia. When these cells replicate,creating daughter cells with damaged or abnormal DNA, which will also grow anddivide more often than normal, it is known as dysplasia. Additionally, cancercells do not exhibit contact inhibition, as the
CancerQuest website explains,which leads to the formation of tumors. Cancer cells reproduce without thenormal external signals, which CancerQuest, an education program at EmoryUniversity, likens to "a car moving without having pressure applied to the gaspedal." The cells, aided by HER3, can reproduce without the usual need forexternal signaling.
The MIT protein works by disrupting HER3's connection with HER2,which cripples HER3 since it has to pair with another receptor, usuallyHER2, to send out growth signals to the rest of the cell. The protein is afused pair of neuregulin molecules, and while single molecules usuallystimulate the HER3 receptor, paired neuregulin molecules bind two adjacent HER3receptors, which blocks them from binding with the HER2 receptors as needed.
In six different kinds of cancer cells in which HER3 isoverexpressed, the protein worked to shut off growth in each one, even in atype resistant to drugs targeting the EGFR receptor.
The next step for the protein is to develop a version moresuited to being tested in living animals, a task the MIT and Brigham andWomen's team is already working on. Testing will be undertaken under theleadership of Steven Jay, co-first author of the paper and a joint MIT/Brighamand Women's postdoc. MIT postdoc Elma Kurtagic and graduate student Seymour dePicciotto are also first authors of the paper, which was published online May26, 2011 in
The Journal of Biological Chemistry.
SOURCE: MIT press release