PHILADELPHIA— Scott Waldman, M.D. Ph.D., chairman of the Department of Pharmacology and Experimental Therapeutics at Thomas Jefferson University, has been awarded one of the prestigious "Provocative Questions" grants from the National Cancer Institute (NCI) , as part of the Institute's ambitious program to tackle the "important but not obvious" questions in cancer to ensure no stone was left unturned after decades of promising research.
Scientists have known for a long time that obesity contributes to cancer risk, but they don't know why.
That's one of the questions set forth by the NCI—24 in total—that Dr. Waldman will help answer with a four-year grant for almost $1.2 million. Out of 700 applicants, just 57 recipients from institutions nationwide were chosen.
For Dr. Waldman, the answers behind cancer and obesity may lie in a hormone receptor known as guanylyl cyclase C (GCC), found mostly in the intestinal tract.
GCC has been established as a suppressor of colorectal cancer tumors and a useful tool to better predict colon cancer risk and recurrence by Dr. Waldman and his team. Preclinical and clinical studies found that lower levels of GCC were associated with an increased risk for colorectal cancer. They also discovered administering GCC reversed that trend.
More recent studies have revealed GCC's role in appetite. The researchers found that silencing GCC affected appetite in mice, disrupting satiation and inducing obesity. Conversely, mice who expressed the hormone receptor knew when to call it quits at mealtime.
Now, under the "Provocative Questions" program, Dr. Waldman will further explore the relationship between cancer and the hormones regulating GCC to get a deeper understanding of the mechanisms of the risk posed by obesity—and a possible therapeutic target to treat it.
This is a promising notion, given that one-third of the U.S. population is considered obese, and that obese people have a 50 percent increased risk of being diagnosed with colorectal cancer.
"We are proposing that obesity increases colorectal cancer risk by suppressing the expression of those hormones, and silencing GCC," said Dr. Waldman, "which is an effect that can be reversed by dietary calorie restriction or oral GCC hormone replacement therapy."
There is potential for immediate translation of results to help reduce colorectal cancer risk in obese patients, given that an oral GCC drug to treat constipation just received regulatory approval, added Dr. Waldman, who is a member of Jefferson's Kimmel Cancer Center.
The Provocative Questions project emerged from discussion among a number of veteran cancer researchers that noticed there were many questions — some important but not very obvious, some that had been asked but abandoned in the past because there were no ways to study or address them, some sparked by new discoveries or novel technologies — that could stimulate the NCI's research communities to use laboratory, clinical, and population sciences in especially effective and imaginative ways.
More than 50 grants, attempting to answer 20 of the 24 proposed questions, with $22 million are being funded this year from that set of applications.
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