A lethal brain tumour's strength may be its weakness
17 August 2010
Malignant gliomas are the most common sub type of primary brain tumour – and one of the deadliest. Even as doctors make steady progress treating other types of solid tumor cancers, from breast to prostate, the most aggressive form of malignant glioma, called a glioblastoma multiforme or GBM, has steadfastly defied advances in neurosurgery, radiation therapy and various conventional or novel drugs.
But an international team of scientists, headed by researchers at the Ludwig Institute for Cancer Research (LICR) at the University of California, San Diego School of Medicine, reports in the August 15 issue of Genes & Development that they have discovered a new signaling pathway between GBM cells – one that, if ultimately blocked or disrupted, could significantly slow or reduce tumor growth and malignancy.
More than other types of cancer, GBMs are diverse assemblages of cell subtypes featuring great genetic variation. Anti-cancer therapies that target a specific mutation or cellular pathway tend to be less effective against such tumor heterogeneity.
''These myriad genetic alterations may be one of the primary reasons why GBMs are so lethal,'' said Frank Furnari, PhD, associate professor of medicine at the UCSD School of Medicine and an associate investigator at the San Diego branch of the LICR.
Even with maximum treatment effort, the median patient survival rate for a diagnosed GBM is nine to 12 months – a statistic that has not changed substantially in decades.
However, Furnari, along with postdoctoral fellows Maria-del-Mar Inda and Rudy Bonavia, and Webster Cavenee, PhD, professor of medicine and director of the San Diego LICR branch, and others noted that in GBMs only a minority of tumor cells possess a mutant form of the epidermal growth factor receptor (EGFR) gene. These cells drive the tumor's rapid, deadly growth. ''Most GBM tumor cells express wild-type or normal EGFR,'' said Furnari. ''Yet when expressed by itself, wild-type EGFR is a poor oncogene.''