Abstract 3909: Iron oxide nanoparticle-leptin receptor antagonist: A novel targeted adjuvant therapy for triple negative breast cancer

Abstract

Abstract Background: Leptin is a cytokine secreted by adipose tissue that binds its receptor, OB-R, leading to increased growth and survival of cancer cells. High levels of leptin have been correlated with poorer outcomes in breast cancer patients, particularly those afflicted with triple negative breast cancer (TNBC). We have created a leptin peptide receptor antagonist, LPrA2, which has been shown to block leptin signaling in several cancer types. To increase its effectiveness, LPrA2 was coupled to iron oxide nanoparticles (IONPs). We aim to determine if IONP-LPrA2 will serve as an adjuvant treatment, when combined with chemotherapeutics, for human TNBC and mouse TNBC-like (Tamoxifen-resistant) breast cancer cells E0771-TAM. Methods: Conjugation of LPrA2 to IONPs was confirmed by Western Blot and inhibition assays. To evaluate the effects of IONP-LPrA2 in mouse TNBC-like cells, the E0771 cell line (progesterone receptor and HER2 negative) was made insensitive to estrogen stimuli by long-term treatment with Tamoxifen (TAM). Human TNBC and E0771 cells, both responsive and unresponsive to estrogen (E0771-TAM), were treated with recombinant leptin and culture medium containing fetal bovine serum plus chemotherapeutics and IONP-LPrA2. Cell cycle progression, cell viability and apoptosis were analyzed using the Cellometer Vision Image Cytometer ®. Results: IONP-LPrA2 was found to cause significant decrease in DNA synthesis during the S phase of the cell cycle in TNBC and TNBC-like cells when compared to E0771 cells. Additionally, IONP-LPrA2 showed additive effects on reduction of cell viability and apoptosis when combined with chemotherapeutics. Conclusion: These findings indicate that IONP-LPrA2 may be useful in the treatment and prevention of TNBC. Further, IONP-LPrA2 treatment may increase the effectiveness and allow for reduction of the dosage of chemotherapeutics. This will in turn attenuate undesired side effects of chemotherapy. These results may be beneficial for breast cancer patients, particularly those with TNBC who are overweight or obese lacking targeted therapy thus suffering the poorest outcomes. Citation Format: Tia L. Harmon, Adriana Harbuzariu, Lily Yang, Ruben R. Gonzalez-Perez. Iron oxide nanoparticle-leptin receptor antagonist: A novel targeted adjuvant therapy for 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 3909. doi:10.1158/1538-7445.AM2015-3909