Abstract 2002: Ganoderma lucidum extract (GLE) reduces stem cell markers in triple-negative breast cancer models via STAT3 regulation

Abstract

Abstract Triple-negative breast cancer (TNBC) is a subtype of cancer described by the lack of estrogen receptor, progestogen receptor, and HER2 receptor. It accounts for approximately 15-20% of all breast cancer (BC) cases worldwide. TNBC aggressiveness might be explained by the presence of BC stem cells (BCSCs), which are a subpopulation of cancer cells involved in tumor initiation, metastasis, and therapy resistance. Interestingly, the signal transducer and activator of transcription 3 (STAT3) participates in the development and progression of BCSCs, but its role in TNBC progression remains unclear. Moreover, BCSCs can be identified by the CD44+/CD24- and ALDH+ phenotype, which correlates with a worse prognosis in TNBC patients. Furthermore, CSCs can be characterized based on the expression of transcription factors involved in stemness (Nanog, Sox2, and Oct4A), where activation of STAT3 leads to enhanced Nanog, Oct4 and Sox2 expression. Importantly, a major challenge arises to develop nontoxic targeted therapies to improve the outcome of TNBC patients. In this regard, our laboratory investigates the role of Ganoderma lucidum extract (GLE), a medicinal mushroom commonly used in complementary and alternative medicine. We hypothesize that GLE will decrease stem cell properties via STAT3 regulation in TNBC cells. Our in vitro results demonstrate that GLE significantly downregulates STAT3 and JAK2 in SUM-149 and MDA-MB-231, TNBC cell lines. In addition, GLE significantly decreases the secretion of IL-6 at 24hr in MDAMB231 cells. Further flow cytometry results show that GLE significantly decreases the CD44+/CD24- population at 24hr and 72hr in MDA-MB-231 cells. In this regard, GLE significantly decreases the expression of ALDH at 24hr and 72hr in MDAMB231 cells. Moreover, GLE decreases the expression of Nanog at 24hr, and all three transcription factors at 72hr. Additionally, our in vivo studies demonstrate that GLE significantly decreases tumor volume of mice injected with CD44+/CD24- sorted cells of the MDA-MB-231 cell line. Finally, tumor weight of GLE treated mice was marginally significantly lower (p=0.053) compared to vehicle. We can conclude that GLE decreases stemness of TNBC via STAT3 regulation. Citation Format: Tiffany J. Rios, Alicia Marti, Gabriela Ortiz, Michelle M. Martínez-Montemayor. Ganoderma lucidum extract (GLE) reduces stem cell markers in triple-negative breast cancer models via STAT3 regulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2002.