Osteopontin expression predicts colon cancer survival

November 7, 2007

NEW YORK (Reuters Health) - Levels of osteopontin, a highly overexpressed protein in several types of solid tumors, are predictive of survival in patients with colon cancer, German researchers report.

"We found that high osteopontin expression in colon cancer identifies patients with aggressive disease and unfavorable prognosis," senior investigator Dr. Klaus-Peter Janssen told Reuters Health.

According to their report in the October 15th issue of the International Journal of Cancer, Dr. Janssen and colleagues at the Technical University of Munich used reverse-transcription PCR to analyze 120 primary colon tumors and 10 liver metastases as well as 9 adenomas and 13 samples of normal colon tissue.

The team found that osteopontin expression was strongly elevated in primary colon cancer and liver metastases, and they established osteopontin expression as an independent prognostic parameter for overall survival.

Moreover, high expression identified a subgroup of patients with poor prognosis.

In this and in further work in mice, the researchers determined that upregulation of osteopontin is dependent on aberrant activation of the Wnt pathway by mutation of the APC tumor suppressor.

Thus, continued Dr. Janssen, his group established "osteopontin as a target gene of the Wnt-signaling pathway, which is deregulated in many colon tumors. Therefore, our findings provide molecular evidence about the regulation of osteopontin in tumor cells."

Moreover, he pointed out, osteopontin is secreted, "which means that one could detect it in the serum of patients -- which would make it a promising candidate for clinical applications, for example, for diagnosis or therapy control."