Antioxidants Curb Cancer's Spread

A QUANTUM OF SCIENCE

New research shows reactive oxygen breaks down cell walls and helps cancer spread

Malignant cancer tumors have a unique characteristic: they can release tumor cells into the lymphatic system and cause tumors to grow elsewhere in the body, even in tissues or organs totally unrelated to those that were the original source of the tumor. This process is called metastasis, and sometimes forces doctors to use whole-body or systemic anti-cancer treatments when a localized treatment targeting a single tumor would be both more effective and far easier on the patient. Now scientist are advancing understanding of how metastasis occurs, and how to prevent it.

Researchers at Burnham Institute for Medical Research in La Jolla, California recently reported that reactive oxygen species were key players in the cellular process of metastasis. Reactive oxygen species (ROS) include superoxide, hydrogen peroxide and other forms of oxygen generated by the body’s normal functions. Some uses of ROS are beneficial, such as when the immune system generates ROS to kill invading cells. In cancerous cells, however, ROS help form lesions and break down cell walls, aiding in the spread of tumor-forming cells. Researchers have isolated a scaffold protein called Tks5 (for Tyrosine Kinase Substrate) which is concentrated in extruded lesions of tumor cells, called podosomes (or invadopodia in some papers). Tks5-rich cells rapidly produce ROS and form lesions that facilitate the spread of tumorous cells throughout the body. In their paper, Burnham scientists show that cells lacking the gene for Tks5 production are substantially inhibited from forming metastatic tumors, and treating the tumor cells with antioxidants similar suppresses the activity of Tks5, resulting in smaller tumors, fewer lesions/podosomes and a substantial decrease in extruded (metastatic) cells.

An example of tumor size reduction in cells lacking the Tks5 gene (4.20 and 4.24):

This paper is an exciting advance in the understanding of the basic processes of malignant cancer. If podosome formation and metastasis can be reduced by either antioxidant treatments or drugs that target Tks5, huge advances can be made in reducing the mortality associated with highly-metastatic malignant cancer.

For more information:

Reactive Oxygen’s Role in Metastasis

A role for the podosome/invadopodia scaffold protein Tks5 in tumor growth in vivo (Blouw et al)

Metastasis (Wikipedia article)

© AQOS / P. Smalley (2009)
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