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Dong Fang, Zhaoguang Lai, Yan Wang
(Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China (mainland))
Med Sci Monit 2019; 25:6639-6648
Biglycan (BGN) is an extracellular matrix (ECM) protein that regulates the growth of epithelial cells. The mammalian target of rapamycin (mTOR) inhibitor, rapamycin, is a treatment for advanced retinoblastoma. This study aimed to investigate the effects of expression of BGN on the response of human WERI-Rb-1 retinoblastoma cells to rapamycin and to investigate the associated signaling pathways.
MATERIAL AND METHODS: BGN gene expression was induced in human WERI-Rb-1 retinoblastoma cells, which were incubated with rapamycin at doses of 0, 5, 10, 20, 30, and 50 μg/ml. Cells were treated with the PI3K/Akt pathway inhibitor, LY294002. The MTT assay determined the rate of cell inhibition. Real-time polymerase chain reaction (RT-PCR) was performed to measure BGN gene expression using RT²-PCR. Western blot detected the protein levels of BGN, p-PI3K, p-Akt, nuclear NF-kappaB, and p65.
RESULTS: Rapamycin impaired cell growth, induced cell apoptosis, and suppressed the expression levels of p-PI3K, p-Akt, nuclear NF-kappaB, and p65. Overexpression of the BGN gene restored growth potential and inhibited apoptosis and was associated with the activation of the PI3K/Akt-mediated NF-kappaB pathway. In cells that overexpressed BGN, inhibition of the PI3K/Akt pathway by LY294002 increased the sensitivity of human WERI-Rb-1 retinoblastoma cells to rapamycin.
CONCLUSIONS: Overexpression of BGN induced rapamycin resistance in WERI-Rb-1 retinoblastoma cells by activating PI3K/Akt/NF-kappaB signaling.