Abstract 2773: Association of ALDH1A1 gene expression with survival of triple-negative breast cancer

Aldehyde dehydrogenases (ALDH) are a family of enzymes that catalyze aldehyde into carboxylic acids via the NAD(P)+-dependent oxidation. Several ALDH family members have been identified in humans, including ALDH1A1, ALDH1A3, ALDH2, ALDH3A1, and ALDH4A1. ALDH1A1 is a crucial element in the retinoic acid signaling pathway regulating the self-renewal and differentiation of normal stem cells. It ALDH1A1 has been suggested as one of breast cancer stem cell markers and may play an important role in breast cancer prognosis. However, previous research on ALDH1A1 and breast cancer prognosis has yielded conflicting results. We analyzed the association between mRNA expression of ALDH1A1 in tumor tissues and survival of triple-negative breast cancer (TNBC: ER-/PR-/HER2-) using data and samples from three cohorts of breast cancer patients, including 469 cases from the Shanghai Breast Cancer Survival Study (SBCSS), 86 cases from the Nashville Breast Health Study (NBHS), and 47 cases from the Southern Community Cohort Study (SCCS). Gene expression levels were measured in total RNA isolated from microdissected archival formalin-fixed paraffin-embedded breast cancer tissues using Nanostring nCounter assays. The associations between ALDH1A1 mRNA expression levels and recurrence/breast cancer mortality and overall mortality were evaluated by multivariate survival analysis using the Cox regression model. Data from the SCCS and NBHS were combined in the analysis because both studies were conducted among US women and had a small sample size. The levels of ALDH1A1 mRNA expression were consistently and positively associated with disease free and overall survival independent of age at diagnosis and TNM stage in both Chinese and US women with TNBC. Compared to those with ALDH1A1 mRNA expression below the median, TNBC patients with ALDH1A1 mRNA expression above the median had a reduced risk of recurrence/breast cancer mortality (HR = 0.60, 95% CI: 0.39-0.92) and overall mortality (HR = 0.70, 95% CI: 0.47-1.05) in the SBCSS and reduced overall mortality in the SCCS/NBHS (HR = 0.27,95% CI: 0.10-0.74). Additional analyses of the SBCSS cohort stratified by basal-like breast cancer subtype showed that ALDH1A1 mRNA expression was similarly associated with reduced risk of recurrence/breast cancer mortality and total mortality in both basal-like and non-basal like TNBC patients, although the point estimates were not significant due to the smaller sample size. In addition, we found that patients with a higher tumor grade had a lower level of ALDH1A1 mRNA expression but did not observe an association with TNM stage. Our study suggests that the mRNA expression of ALDH1A1 in tumor tissue may be associated with favorable clinical outcomes in patients with TNBC. Further investigations are needed to understand the biological mechanism(s) underlying the observed association. Citation Format: Yan Liu, Qiuyin Cai, Ying Zheng, Michelle L. Baglia, Yinghao Su, Sarah Nechuta, Ping-Ping Bao, William Blot, Wei Zheng, Xiao-Ou Shu. Association of ALDH1A1 gene expression with survival of triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2773. doi:10.1158/1538-7445.AM2015-2773