Abstract 4706: Gene and protein expression of TGF-beta signaling pathway molecules in women undergoing reduction mammoplasty

Abstract Gene and protein expression of TGF-beta signaling pathway molecules in women undergoing reduction mammoplasty. Introduction: The TGF- β signaling pathway is involved in growth, differentiation, apoptotic and senescence processes; it also participates in the malignant transformation events that lead to breast cancer. Hypothesis: TGF- β expression might contribute to the risk of breast cancer. Methods: As part of an ongoing epidemiology study conducted at the Lombardi Cancer Center in Georgetown University, we collected breast tissue samples from women undergoing reduction mammoplasty without history of cancer. We obtained histological slides from 92 women and performed immunohistochesmistry staining against TGF-β1, TGF-β2, TGF-β3, TGF-βR1 and TGF-βR2. The Allred scoring system was used to asses the intensity and distribution of the staining in each slide (in a scale of 0 to 6). Additionally, we extracted RNA from frozen tissue samples in RNA-later solution from 75 women and assessed the gene expression of the TGF-β signaling pathway by quantitative-PCR (relative quantification against endogenous RNase-p). Results: We found the staining highly specific and confined mainly to lobular structures; TGF-β2 (median A-score 6, SD 0.9009), TGF-βR1 (median A-score 6, SD 0.6603) and TGF-βR2 (median A-score 6, SD 0.7460) scores were higher than TGF-β1 (median A-score 0, SD 1.8485) and TGF-β3 (median A-score 5, SD 0.6450), and we noticed high levels of TGF-β1 in 9 women with proliferative lesions (atypical hyperplasia), when compared against women without lesions (Fisher's exact test P<0.0001). When we examined the localization, the staining was predominantly cytoplasmic among all the molecules studied, however, we identified also nuclear staining in TGF-βR1 and some TGF-βR2, moreover, we identified particularly intense TGF-βR2 staining in myoepithelial cells. We found a very uniform gene expression among the three ligands and two receptors of the TGF-β pathway: for TGF-β1 the median RQ was 1.321, and the SD 2.091; for TGF-β2 the median RQ was 1.361, and the SD 1.301; for TGF-β3 the median RQ was 1.291 and the SD 1.799; for TGF-βR1 the median RQ was 1.424, and the SD 2.266 and for TGF-βR2 the median RQ was 1.281 and the SD1.072. There were no significant differences in the expression of the TGF-β molecules (ANOVA P=0.3475), which in addition to the IHC analysis, indicates that the modulation on TGF-β signaling pathway occurs at the post-transcriptional level. Conclusion: There is an interindividual variation in the gene expression of TGF-β signaling pathway molecules in healthy women, and TGF-β1 protein expression is increased in women with proliferative lesions in their breast tissues. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4706.