Parity-Associated Gene Expression and Breast Cancer in Premenopausal Women
Posted: Wednesday, July 31, 2019
Jose Russo, MD, FACP, of the Fox Chase Cancer Center in Philadelphia, and colleagues may have identified the biologic basis behind the decreased risk of breast cancer after pregnancy at a young age. This work, published in Breast Cancer Research, is the culmination of an international effort to analyze the DNA of healthy premenopausal women who have had one or more full-term-pregnancies to determine what genetic signatures may be protective against cancer.
The study focused on 109 premenopausal women (30 nonparous, 79 parous), and 43 different expressed genes were discovered. The analysis also revealed 286 deferentially expressed genes: 238 upregulated and 48 downregulated.
The investigators observed three distinct patterns in the gene expressions. First, transient genes were upregulated after a full-term pregnancy but returned to nonparous levels and showed T-cell activation. Second, the expression of long-term changing genes decreased over time after a full-term pregnancy but not to nonparous levels and identified with immune response and development were identifie. Third, long-term constant genes remained elevated in parous versus nonparous breast independently of the time since pregnancy.
The researchers concluded that parous premenopausal breast tissue has a unique gene profile that may be responsible for protection against breast cancer. The genes involved in the immune response are related to T-cell activation after a full-term pregnancy, and after 5 years, the levels returned to normal levels. Along with the T-cell response, the genes that are permanently affected by pregnancy may be the preventative mechanism against breast cancer after a full-term pregnancy.
“Parous premenopausal breast shows a specific transcriptome profile, in which genes controlling chromatin remodeling and cell differentiation are activated after [full-term pregnancy] and stay upregulated for many years,” the investigators concluded.
Disclosure: The study authors reported no conflicts of interest.