New studies show that obese male mice, who mate with normal weight female mice, produce female pups that are overweight at birth and well into their childhood. These baby mice also develop breast tissue later than usual and have an increased rate of breast cancer.

The researchers believe they have located evidence that obesity actually changes the microRNA (or miRNA) signature (epigenetic regulators of gene expression) in both dad’s sperm and the breast tissue of their daughters. This suggests that miRNA may carry the epigenetic information from obese dads directly to their unborn daughters. The miRNA’s help in the regulation of insulin receptor signaling, which is linked to changes in body weight as well as other molecular pathways that are associated with the development of cancer, similarly to the hypoxia signaling pathway.

Obesity seems like it tends to run in families, as do some forms of breast cancer. Maternal obesity is thought to influence both conditions in humans. A woman who is larger during her pregnancy may produce larger babies. These babies may be at a higher risk of developing breast cancer later on in life. A lot of the focus has been related to the maternal side of things, there have not been many studies that looked at the influence of a father’s health on his future offspring’s risk of cancer.

The lead investigator of the study, Sonia de Assis, is an assistant professor in the department of oncology at Georgetown Lombardi. She says this study provides us with the evidence that a father’s body weight at the time of conception, in animals, affects not only his daughter’s body weight at time of birth and during her childhood, but also affects her level of risk when it comes to developing breast cancer later on in life. Of course, the study was done on mice, but it recapitulates recent findings in humans which show that obese men have very significant epigenetic alterations in their sperm compared to leaner men. This animal study suggests that those epigenetic alterations in sperm may have consequences for next generation cancer risk.









De Assis says the next step in the research is to see if the same associations can be linked between human fathers who are overweight at time of conception and the risk of breast cancer among their daughters. She goes on to say that until we know about this association in men, we should stick to what we all know is a good piece of advice: both women and men should continue to try their best to eat a well-balanced diet, maintain healthy body weight and live a life style that promotes such things. Not only will this benefit each of us as individuals, but it could potentially lead to much healthier and happier children, whether we plan on getting pregnant anytime soon or not. Prevention is the key to success when it comes to health and routines are difficult to break once those strong habits are formed.

The team plans to continue their studies to get direct answers about the human repercussions of fathers being overweight at the time of conception on their unborn children. Other animals may be tested as well to get a better idea as to how these changes occur and if there are any ways technology can go about altering the potential outcomes. There may be certain genes that minimize the risk for cancer even if patients who should have a much larger risk.

The latest findings were published online in the June 24th edition of Scientific Reports journal by researchers from the Georgetown Lombardi Comprehensive Cancer Center. The discovery comes from one of the first animal studies that examine the impact of paternal obesity on future generations’ cancer risk.