Abstract 1672: Ganoderma lucidum (Reishi) induces autophagy in inflammatory breast cancer cells to promote cell death.

Abstract

Abstract Autophagic cell death is an important physiological cell death process that is characterized by massive degradation of cellular contents by means of intracellular membrane/vesicle reorganization and lysosomal activity. Herein, we test the autophagy inducing effects of the medicinal mushroom Ganoderma lucidum (Reishi) in the inflammatory breast cancer (IBC) cell line, SUM-149. IBC is a rare, lethal and aggressive form of advanced breast cancer with poor prognosis and no targeted therapy. Because the mechanism is not well defined, some autophagic cell death events might be attributed to apoptosis. This death or survival mechanism depends on cell type and cells stress, since in such cases the induction of both, autophagy and other pro-death signals (i.e. BAX), occur in parallel. Our hypothesis is that Reishi induces autophagy in IBC cells to promote cell death. SUM-149 cells were treated with 0.5mg/mL of Reishi for 2h, 4h, 6h, 8h, 12h and 24h. Cells were lysed and equal total protein was western blotted against Beclin-1, Atg5, Atg12 and LC3B autophagy proteins. To confirm autophagy effects on cell viability, cells were treated with 3-methyladenine (3-MA), chloroquine (CQ) and PP242 with or without Reishi for 24 hours. Cells were fixed and stained with propidium iodide to assess viable nuclei. Herein we show that Reishi affects the expression of autophagy-associated molecules depending on treatment time. Reishi increases the expression of autophagy proteins in IBC. Moreover, the autophagy inhibitors increased cell viability after 24h, while cancer cell viability decreased when Reishi was added. Autophagy inducer PP242 alone and in combination with Reishi decreased cell viability and induced the expression of the pro-apoptotic protein, BAX. Thus, we demonstrate that Reishi induces autophagy, promoting cell death in IBC cells, as cancer cell viability is reduced, with a subsequent increase in pro-apoptotic protein expression when Reishi is added. Our findings are the first to show a novel mechanism responsible for the inhibition of IBC cell viability by Reishi demonstrating its potential for use in treatment of cancer. This project was sponsored by Title V PPOHA US Dept of Education #P031M105050 to UCC, NIH/RCMI #2G12RR003035 to UCC, NIH/INBRE #5P20RR016470 to UPR/UCC, NIH/NCRR #U54RR026139 to UPR/UCC, and a research donation from the Commonwealth of Puerto Rico to UCC-Centro Universitario de Medicina Integral y Complementaria (CUMIC) / MMM. Citation Format: Raysa Rosario-Acevedo, Tiffany Rios, Ivette Suarez-Arroyo, Luis A. Cubano, Michelle M. Martínez-Montemayor. Ganoderma lucidum (Reishi) induces autophagy in inflammatory breast cancer cells to promote cell death. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1672. doi:10.1158/1538-7445.AM2013-1672