Cancer cells' evasive action revealed

Researchers at Rice University and the University of Texas MD Anderson Cancer Center have uncovered a trick used by lung cancer cells to hide from the body’s immune system.

The researchers have found links between subtle actions and reactions that allow cancerous cells to spread with little to stand in their way. The team led by Dr. Edwin Ostrin, an assistant professor of pulmonary medicine at MD Anderson, and theoretical biological physicist Herbert Levine at Rice, details its findings in study in this week’s Proceedings of the National Academy of Sciences.

The study shows for the first time that some aggressive lung cancer cells display significantly reduced expression of proteins known as immunoproteasomes, a key player in the process that signals the immune system’s T-cells to attack diseased cells. The researchers suggest it may be possible to enhance the production of these proteins to override the cells’ escape mechanism.

Immunoproteasomes are produced inside cells, where they degrade unneeded or damaged proteins, including those produced by invading pathogens. The degraded pieces are secreted by the cell and bond to its surface and create beacons that inform nearby T-cells of the cell’s diseased nature.

If T-cells don’t sense these surface beacons, called antigens, a cancer is more likely to evade detection and destruction. Data gathered over the years by MD Anderson researchers shows patients with early stage non-small-cell lung cancer – the most common type – who have low expression of immunoproteasomes are more likely to see their cancers return after treatment and metastasize.