How expanding waistlines may contribute to cancer growth

Investigators at The University of Texas Health Science Center at Houston (UTHealth) have found a new link between cancer and obesity. Their preclinical research findings have suggested that fat progenitor cells may contribute to cancer growth by fortifying the vessels that provide needed blood to tumours. Studies of groups of people have demonstrated a link between obesity and certain cancers; however, the physiological causes have not been identified. The World Health Organization reports that in 2008 there were more than 1.4 billion obese adults in the world and that cancer claimed the lives of 7.6 million that year. Some researchers have theorized that what obese people eat may affect cancer progression. However, although diet is an important factor, the direct effect of excess fat tissue on tumours has to be taken into consideration, said Mikhail Kolonin, Ph.D., senior author and associate professor at the Center for Stem Cell and Regenerative Medicine at the Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases at UTHealth. The UTHealth scientists found a new link between tumor growth and obesity. They report that tumours emit a signal that attracts progenitor cells from white adipose tissue in mouse models of cancer. These cells in turn support the network of blood vessels that nourish tumours - a process called tumour angiogenesis. “For the first time, we have demonstrated that excess fat is a key factor in cancer progression regardless of the diet contributing to the extra weight,” Kolonin said. “In an attempt to understand how fat tissue fuels tumour growth, our laboratory has focused on a possible role of adipose stromal progenitor cells. These cells serve as stem cells in fat tissue. We have discovered that they expand in obesity and are mobilized into the systemic circulation,” Kolonin said. “Our experiments show that fat progenitors are recruited by tumours, where they incorporate into blood vessels and become fat cells,” said Yan Zhang, M.D., Ph.D., the study’s lead author and research scientist at the UTHealth Medical School. “We found that obese animal fat progenitor cells recruited by tumours improved vascular function and, therefore, increased survival and proliferation of cancer cells,” Zhang explained. Chieh Tseng, study author and graduate research assistant at the The University of Texas Graduate School of Biomedical Sciences at Houston, said, “Our work has the potential to help a lot of people. Currently, we are investigating the molecular mechanisms of fat progenitor cell homing to tumour. We are also screening for new molecules targeting the pathways through which cells traffic from fat tissue to promote tumour growth.” “The next step in this research would be to inactivate fat progenitor cells in an effort to slow cancer progression,” said Kolonin, who is on the faculty of the graduate school and is the holder of the Jerold B. Katz Distinguished Professorship in Stem Cell Research at UTHealth. The results were reported in Cancer Research, a journal of the American Association for Cancer Research. ANI