title: Rapamycin, an mTOR inhibitor, induced apoptosis via independent mitochondrial and death receptor pathway in retinoblastoma Y79 cell.
abstract: Rapamycin is helpful in the treatment of certain cancers by inhibiting mTOR (mammalian target of rapamycin) pathway. Here, rapamycin mediated apoptosis were investigated in human retinoblastoma Y79 cells. The MTT assay showed that the IC50 value of rapamycin against Y79 cells was 0.136 ± 0.032 μmol/L. Flow cytometry analysis indicated that the percentage of apoptotic cells was increased from 2.16 ± 0.41% to 12.24 ± 3.10%, 20.16 ± 4.22%, and 31.32 ± 5.78% after 0.1, 0.2, and 0.4 μmol/L rapamycin or without rapamycin treatment for 48 hours. Flow cytometry analysis showed that rapamycin induced mitochondrial membrane potential (∆Ψm) collapse in Y79 cells in a concentration-dependent manner. Western blot assay showed that rapamycin led to release of cytochrome c from mitochondrial membranes to cytosol. Further Western blot assays showed that rapamycin induced activation of caspase-9 and caspase-8 and the cleavage of caspase-3. Rapamycin induced cleavages of caspase-3 and apoptosis was inhibited by both Z-LETD-FMK and Z-IETD-FMK treatment. Together, all these results illustrated that rapamycin induced apoptosis in human retinoblastoma Y79 cells involvement of both intrinsic and extrinsic pathways.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060, China.
authors.forename: Yan-Dong
authors.initials: YD
authors.lastname: Wang
authors.affiliation: The First Affiliated Hospital, Sun Yat-sen University Guangzhou 510080, China.
authors.forename: Yong-Jing
authors.initials: YJ
authors.lastname: Su
authors.affiliation: The First Affiliated Hospital, Sun Yat-sen University Guangzhou 510080, China.
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Li
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060, China.
authors.forename: Xiang-Chao
authors.initials: XC
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060, China.
authors.forename: Guang-Jiang
authors.initials: GJ
authors.lastname: Liang
keywords: Retinoblastoma; extrinsic apoptosis signaling pathway; intrinsic apoptosis signaling pathway; rapamycin