A report on this work appears in the Nov. 2 issue of the journal Nature.
Retinoblastoma occurs in about 5,000 young children worldwide each year, arising from the immature retina, which is the part of the eye responsible for detecting light and color. The cancer is fatal if left untreated.
The new treatment holds promise for a simpler, more effective and less-toxic treatment for retinoblastoma that would eliminate the need for the current, complex therapy, according to senior author Michael Dyer, Ph.D., a Pew Scholar and associate member of the St. Jude Department of Developmental Neurobiology. The treatment is based on a discovery by Dyer's laboratory that overturned a widely held belief about the process of apoptosis (cell suicide) in retinoblastoma. Apoptosis is the way the body rids itself of abnormal cells that might become cancerous or cause other problems.
Until now, retinoblastoma experts thought that a mechanism called the p53 pathway triggered apoptosis in other types of cancer cells, but not in retinoblastoma. However, the St. Jude team proved not only that the p53 pathway was activated in early-stage retinoblastoma, but that excessive levels of a molecule called MDMX blocked it from triggering apoptosis in more advanced tumors. Based on this discovery, the St. Jude team used a molecule called nutlin-3 to block MDMX in retinoblastoma cells in test tube studies as well as in mouse models. The molecule was originally developed by
Source:St. Jude Children's Research Hospital