The primary cause of death from colon cancer results from metastases that withstand conventional therapy and escape locoregional control. The molecular regulation of the tumor cell's acquired ability for invasion and metastasis is still not completely understood and progress in this field may generate novel therapeutic targets. Osteopontin (OPN) has recently been identified as a lead marker for colon cancer progression with elevated OPN expression correlating with advanced stage and poor survival. This key regulator of metastasis has been shown to induce invasive mechanisms, increase motility, adhesiveness, angiogenesis, and enhance evasion of the immune system to augment the metastatic potential in colon cancer cells. This review will discuss the basic mechanisms underlying tumor metastasis, recent innovations used to screen and identify metastatic genes in colon cancer, and model systems used to analyze these potential targets. Target genes associated with activation of OPN, a master regulator of tumor metastasis, will be described in the context of a colon cancer model. Finally, the innovative techniques of RNA interference and aptamer technology for targeting metastasis genes will be reviewed.
Cancer - Metastasis - Osteopontin - Microarray siRNA - Aptamer