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Bruno F. Fernandes, Alexandre N. Odashiro, Sebastian Di Cesare, Aimee Huynh, Patricia R. Odashiro, Miguel N. Burnier, Jr.; HIF-1α Signalling Promotes Proliferation in Retinoblastoma Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1874. doi: https://doi.org/.
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Overexpression of HIF-1α, a subunit of HIF1 and a major regulator of cellular hypoxic signalling, occurs in many solid tumors and is often associated with poor patient prognosis. Previous studies have indicated that hypoxic regions exist in Retinoblastoma (RB) and the RB protein interacts with HIF-1α. To date, functional roles of HIF-1α have yet to be studied in retinoblastoma. The aim of this study was to determine whether or not HIF-1α expression contributes to proliferation of RB cells in culture.
The human RB cell line Y-79 was cultured in control media or in the presence of cobalt chloride (CoCl2; 50uM) for 24 hours. CoCl2 is a hypoxia-mimicking agent that stabilizes cytoplasmic HIF-1 and promotes HIF1-mediated signalling. After 24h, cells were treated with either HIF-1α-specific siRNA or non-targeting negative control siRNA and left in culture for 48 hours. Cells were then harvested for MTT-based proliferation assays. Results from the proliferation assay were compared using a Student’s T-test and a p<0.05 was considered statistically significant. Morphological assessment of cells was performed microscopically to evaluate cell viability.
HIF-1α RNA levels were increased in all CoCl2-treated cells compared to control cells. Knockdown of HIF-1α in control and CoCl2-treated RB cells resulted in a statistically significant decrease in proliferation. No control or experimental condition led to morphological changes consistent with cell death.
Retinoblastoma cells characteristically outgrow their blood supply generating ischemia and a hypoxic environment. This study demonstrated that hypoxia induces the proliferation of Retinoblastoma cells through HIF-1α signalling, without causing cell death. Therefore, targeting this pathway may represent an adjuvant therapeutic strategy in Retinoblastoma patients.
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