The presence of high levels of a particular protein in tumors drives metastasis, providing a valuable biomarker for predicting the spread of cancer.

Mechanisms governing metastasis—a major cause of mortality in cancer patients—remain elusive, noted Y. Peng Loh of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and fellow researchers in their online report of their protein discovery (The Journal of Clinical Investigation, www.jci.org/articles/view/40433/pdf). However, the team helped shed light on this process by finding that the carboxypeptidase E gene is alternatively spliced in human tumors to yield an N-terminal truncated protein that drives metastasis. Evidence of this process was seen in human metastatic colon, breast, liver, and head and neck cancer cell lines.

By measuring the protein’s genetic material in human tumors and the genetic material from surrounding tissue, the investigators could predict at least 90% of the time whether a cancer would spread within 2 years, regardless of cancer stage. They call for more studies to explore this “potentially powerful biomarker for predicting future metastasis and recurrence.”