PDA

View Full Version : Gremlins in the "neighborhood" cause cancers to grow


Lani
11-09-2006, 10:22 PM
Stanford Report, November 8, 2006
Bad neighbors may cause cancer

THE QUESTION: Do cells in the microenvironment surrounding a tumor play a role in tumor development?

BACKGROUND: Previous research has seemed to suggest that a tumor cell's micro-environment plays an important role in cancer progression: It's sometimes difficult to grow cancer cells outside the body, and non-cancerous cells in people susceptible to certain cancers may differ from those same types of cells in people who lack that susceptibility. Stem cells also depend on external signals to determine when to differentiate and when to make more stem cells. One of these signals uses bone morphogenetic proteins, or BMPs, which tend to slow cell division and promote differentiation.

THE STUDY: The authors compared gene expression profiles of stromal cells cultured from human skin with and without a nearby skin cancer called a basal cell carcinoma—one of the most common human cancers. They also compared the profiles of the cancerous and non-cancerous skin cells.

THE FINDINGS: Although the cancer cells expressed BMPs, the nearby stromal cells made significant amounts of a protein called Gremlin 1 that counteracted BMPs' effect. When cancerous skin cells are cultured, BMPs slow their growth and Gremlin increases their growth. The researchers found that Gremlin expression is increased in stromal cells near many different kinds of cancer, but is nearly undetectable in stromal cells from the corresponding normal tissue. These findings suggest that these cells in the tumor microenvironment may play an important role in the initiation and progression of many types of human tumors.

WHY IT MATTERS: The fact that BMPs may be involved in regulating both stem cells and tumor cells is significant for two reasons: It may aid the development of new cancer diagnoses and treatments, and it highlights the biological importance of the micro-environment, or niche, for both stem cells and tumor cells. It may also help determine how stem cells decide to proliferate and differentiate, and enhance future therapeutic opportunities with these cells.

CAVEATS: The addition of Gremlin alone to a culture of basal cell carcinoma cells was not enough to support long-term growth of cultured tumor cells, suggesting the involvement of other as-yet-unidentified factors.

FIND THIS STUDY: The paper was published online Oct. 3 by the Proceedings of the National Academy of Sciences, at http://www.pnas.org/[/url].