Cancer support cells may promote growth

Cancers may cause surrounding supportive cells to evolve and ultimately promote cancer growth, say scientists at the University of North Carolina, Chapel Hill. Their research offers what is believed to be the first evidence that mutations within cancer cells can signal surrounding tissues to alter their molecular composition in ways that promote tumor growth and proliferation. Moreover, their findings suggest that cell mutations that promote cancer progression may arise in cells other than the predominant cancer cell.

While not offering immediate application to the treatment of human cancers, the research indicates that new anti-tumor therapies may be more effective if their targets are broadened to include molecules within supporting cells of the cancer. These additional target cells are in the tumor's surrounding "microenvironment," or stroma, including the supporting connective tissue that forms the framework of organs such as the breast, colon, and prostate. They also are found in the tumor's blood vessels, or its vasculature.

"Basically, virtually all the studies on genetic changes or changes in gene expression have focused on the cancer cell, on events within the cancer cell itself," points out Terry Van Dyke, professor of genetics, biochemistry, and biophysics. Thus, research focused solely on the predominant cancer cell, such as epithelial cells that form the bulk of many tumors, including breast cancer, would be on the accumulated mutations that have allowed the cell to survive and grow unchecked.

"However, during the last several years, it has become increasingly clear that cancer involves complex interactions among different types of cell compartments and, as in any organ, these compartments comprise blood vessels, supporting tissue, and immune cells," Van Dyke declares. "The interaction between the predominant cancer cell type and other types of surrounding cells is important in the development of disease."

The signals that go back and forth between cells contain selective pressures, not only on the cancer cell itself, but on the surrounding cell as well. "Think of it as a microcosm of evolution, such that every change that goes on in the cancer cell can impact cells around it," says Van Dyke of the process. "It's a back-and-forth cross-talk via which the whole entity evolves, not just a subset of cells within the cancer. It's an environment where changes in the surrounding cells are selected that will help tumor growth."

Van Dyke and her collaborators' research suggests a need to look at cancer development as a more dynamic process and expand the approach for treatment. "If the changes you're targeting in the predominant cancer cell are going to affect, say, the supportive tissue, it may be best to develop therapies that hit both types of cell," she concludes.

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