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Sandipan Datta, Gino Cortopassi; Mitochondrial bioenergetic characetrization of cellular models of retinoblastoma. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1626.
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© ARVO (1962-2015); The Authors (2016-present)
Recently a study has shown massive mitochondrial defficiency in clinical samples of retinoblastoma. Loss of mitochondrial complex 1 positively correlated with poor tumor differentiation and invasion. The objective of this study was to validate the mitochondrial deficiency in cellular models of retinoblastoma.
Mitochondrial O2 consumption of Y79 and WERI-Rb1 two commercially available retinoblastoma cell was measured using Clarke's electrode. ARPE-19 a retinal pigmented epithelial cell line was used as a control for comparison. Relative expression of mitochondrial DNA:nuclear DNA ratio in ARPE-19, Y79 and WERI-Rb1 was evaluated by qPCR. Relative expression of mitochondrial DNA encoded MT-ND2, MT-TL1, CYB, and nuclear DNA encoded Nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or Nrf2), HO1, NQO1 and ATF5 was measured by qRT-PCR.
Mitochondrial O2 consumption rate of Y79 was lower than ARPE-19 while the mitochondrial O2 consumption rate of WERI-Rb1 was higher when compared to ARPE-19. Expression of two out of three mitochondrially encoded genes (MT-MD2 and MT-TL1) at mRNA level was significantly elevated in both the retinoblastoma cell lines compared to ARPE-19. We measured relative expression of mitochondrial DNA to nuclear DNA ratio in these cell lines. The mt-DNA/n-DNA was significantly lower in both the retinoblastoma cell lines when compared to control. Furthermore we investigated the expression of Nrf2-target genes as Nrf2 pathway is an important mediator of mitochondrial biogenesis. Nrf2-target genes such as HO1 and NQO1 was downregulated in retinoblastoma cells compared to ARPE-19. In addition, activating transcription factor 5 (ATF5) was significantly upregulated at the mRNA level.
Y79 and WERI-Rb1 cells were found to have normal mitochondrial function in vitro when compared to ARPE-19. In fact we observed significant upregulation in the mitochondrially encoded transcript for MT-ND2; a complex 1 subunit. Retinoblastoma cells also have significantly impaired Nrf2 pathway and upregulated ATF5. These can be potential new targets for the drug discovery efforts in retinoblastoma.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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