Use of immunofluorescence to assess the efficacy of mTOR pathway therapeutic agent Everolimus in breast cancer

• Main Authors: Chun-Ting Kuo, 郭俊廷
• Other Authors: 胡文聰
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/dmthy5

碩士 === 國立臺灣大學 === 應用力學研究所 === 105 === In many solid tumors, the PI3K/AKT/mTOR pathway is activated and is believed to play major roles in a range of cellular functions. Downstream of this pathway, pho-4EBP1 and pho-S6K1 perform critical role in controlling biological processes. In breast cancer, when patients start to exhibit resistance with hormonal therapy or chemotherapy, mTOR inhibitor, for example Everolimus, is often considered, which can deregulate the PI3K/AKT/mTOR pathway by allosteric binding the catalytic site of mTORC1. But in some mTOR-targeted therapy cases, Everolimus does not exhibit the desired efficacy. This work assesses the use of immunofluorescence analysis to predict the efficacy of the mTOR inhibitor Everolimus using breast cancer cell lines- Hs578T, MCF7, BT474, MDA-MB-231-and patient-derived cell culture (PDCC)-ABC-82T, and ABC-16TX1.These cells provided predictive information on the sensitivity of Everolimus using cell viability and MTT assays based on immunofluorescence intensities of pho-4EBP1 Thr37/46 and pho-S6K1 Ser424. Results show that the immunofluorescence analyses can be used to indicate the efficacy of mTOR inhibitor Everolimus on cells tested. Independently,pho-4EBP1 Thr37/46 and pho-S6K1 Ser424 immunofluorescence expression can classify into different groups based on their intensities for cell lines and PDCC. The combined immunofluorescence intensity of pho-4EBP1 Thr37/46 and pho-S6K1 Ser424 is representative of the efficacy of Everolimus. Results also suggest that dynamitic change for pho-4EBP1 and pho-S6K1 occur when cells have resistance characteristic of Everolimus. Further, mTOR resistance is not only consequence of AKT/mTOR but also by LKB1 or MAPK/ERK pathway.Furthermore, LKB1 and pho-GSK3β may also be potential markers to predict the efficacy of Everolimus therapy.