The role of stress in modulating AIPB expression and estradiol synthesis in triple-negative breast tumors.

e13146 Background: In the United States, invasive breast cancer affects 1 in 8 women during their lifetime, with over 3.8 million individuals living as survivors. Breast cancers vary, with some being hormone-responsive and categorized on the presence or absence of estrogen (ER), progesterone (PR), and HER2 receptors. While targeted therapies exist for Estrogen Receptor positive (Er+) and Progesterone Receptor positive (PR+) cancers, triple-negative breast cancer (TNBC), which lacks all three receptors, affects about 15% of patients and is unresponsive to effective molecular treatments. Only a fraction of the cases respond to chemotherapy which emphasizes a need for new prognostic markers and treatments. Aromatase is the key enzyme in converting testosterone to estradiol which plays a crucial role in tumor growth, especially after menopause. Our research lab has identified the “Aromatase Interacting Partner in Breast or AIPB, whose overexpression inhibits aromatase, leading to a reduction in estradiol levels. However, in triple-negative breast cancer, there is an increase in AIPB expression when compared to ER+/PR+/Her2- breast tumors or unaffected women. This devastating prognosis and low survival rates can contribute to a considerable amount of stress in the diagnosed patients, in turn leading to an increase in cortisol production. Our hypothesis suggests that this stress or increase in cortisol could alter AIPB production in the tumorigenic cells which could potentially lead to a decrease in estradiol synthesis. Methods: Stress stimulation was achieved in a lab setting by subjecting engineered triple-negative breast cancer cells, capable of conditional AIPB overexpression upon tetracycline addition, to a 42 °C heat shock for various durations (0,15, 30, 45 minutes). Results: Following the 45 minutes of stress, MDA-MMD-231 cells exhibited a significant reduction in estradiol levels, decreasing from 160ng/ml to 100ng/ml. MDA-MD-231 cells engineered to overexpress AIPB produced only 62ng/ml of estradiol, marking an 18.75% decrease. The introduction of doxycycline led to a further reduction in estradiol levels to 47ng/ml, which is approximately a 29.4% drop. Western blot analysis using a CT antibody revealed heightened AIPB expression in MDA-MD-231-AIPB cells when stress and doxycycline treatments were combined. Conclusions: Given the absence of aromatase in triple-negative breast cancer, our findings suggest that AIPB’s role in estradiol production is independent of aromatase, highlighting its significance in these cancer cells. The data supports the hypothesis that enhancing AIPB expression could potentially improve patient outcomes by reducing estradiol synthesis.