Transforming Growth Factor-β in Breast Milk from Women with Breast Biopsies
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About 1 in 8 (12%) American women will develop invasive breast cancer during their lifetime, and around 40,000 of them are estimated to die from it in 2012 alone (American Cancer Society, 2012). Diagnosis of breast cancer in young women is already difficult (Mintzer et al., 2002) and is further complicated when a woman gets pregnant or is breastfeeding because her breasts get denser, making clinical examination and mammography difficult to interpret (Schedin, 2006). As opposed to painful and invasive methods of tissue acquisition such as biopsies, human milk can be used to measure certain biomarkers in the breast, such as methylation, as previously demonstrated by the Arcaro lab (Browne et al., 2011). Transforming growth factor-β (TGF-β) is a naturally-secreted protein in breast milk (Saito et al., 1993). It is a multifunctional cytokine that is believed to play a role in cancer progression (Akhurst and Derynck, 2001), especially in pregnancy-associated breast cancer (Flanders and Wakefield, 2009). In our observational study, we investigated the expression levels of TGF-β2, one of the three isomers of TGF-β, in breast milk from both breasts of 182 women who were scheduled to receive a biopsy each. They either had breast biopsies prior to or during their pregnancies, or after childbirth. The aim of our project was to examine the relationship between trends in TGF-β expression across different variables such as biopsied versus non-biopsied breast, biopsy category, the mother’s age at first birth and her age at the time of milk donation, parity (number of live births), baby’s age at the time of milk donation etc. Our results show that TGF-β2 levels vary greatly among our sample population, and none of the variables we examined (except being Caucasian) were significant upon regression. A larger sample size is needed to make further conclusions and perhaps other isoforms of TGF-β need to be analyzed to determine the role of TGF-β in this population.