TAMPA, Fla., June 21 (UPI) -- While cancer cells are an invasive force against tissues in the body, they are not all created equal, nor do they necessarily develop in a random way, according to new research.
Scientists at the Moffitt Cancer Center found in a study of breast cancer that cells closer to the center of a tumor are more attuned to using resources, while those at the outer edges specialize in cellular invasion that leads to tumor growth.
The general thought has been that cancer cells develop from random mutations, but the scientists say subpopulations of cells differentiate in an evolutionary manner aimed at survival and growth, knowledge that may lead to better cancer treatments.
The scientists compare a tumor's cells to invasive toads in Australia, each of which moves differently and has evolved to serve a specific purpose as part of an invading movement of toads.
"Interestingly, differences within a single population [tumor cells] are seen in biological invasions in nature," Dr. Robert Gatenby, chair of the department of diagnostic imaging and interventional radiology at Moffitt Cancer Center, said in a press release. "For example, the cane toad has been invading Australia for many years. The cane toads at the edge of the invasion have bigger legs presumably because they are adapted to moving farther and faster."
For the study, published in the journal Cancer Research, the scientists developed a mathematical model based on evolutionary theories to show differences in cell populations within a tumor. The model operates on the idea that cancer cells can either invest in reproduction by invading and killing other cells, or the ability to survive by feeding off the environment around them, such as blood vessels, but not both.
The scientists found, based on the model of tumor function, that cells at the edges of tumors are focused on invasion and reproduction, while those inside compete with neighboring cells for resources in the environment around them.
Comparing tumor cells to the toads, the scientists say that while the inner cells are focused on nutrients, they are also more static and die faster, compared to cells on the outer tumor edges which have higher rates of proliferation.
In toads, this is reversed, as the toads on the outside of an invading population -- the ones with bigger legs to move farther and faster -- end up with severe spinal arthritis about 10 percent of the time because of the one physical difference.
The hope is for this new understanding to inform future research into promoting non-invasive cell characteristics to those at the edge of a tumor and slow growth during treatment, the scientists said.