Abstract
AbstractThere are indications that pharmacological doses of ascorbate (Asc) used as an adjuvant improve the chemotherapeutic management of cancer. This favorable outcome stems from its cytotoxic effects due to prooxidative mechanisms. Since regulation of intracellular Ca2+ levels contributes to the maintenance of cell viability, we hypothesized that one of the effects of Asc includes disrupting regulation of intracellular Ca2+ homeostasis. Accordingly, we determined if Asc induced intracellular Ca2+ influx through activation of pertussis sensitive Gi/o-coupled GPCR which in turn activated transient receptor potential (TRP) channels in both etoposide-resistant and -sensitive retinoblastoma (WERI-Rb1) tumor cells. Ca2+ imaging, whole-cell patch-clamping, and quantitative real-time PCR (qRT-PCR) were performed in parallel with measurements of RB cell survival using Trypan Blue cell dye exclusion. TRPM7 gene expression levels were similar in both cell lines whereas TRPV1, TRPM2, TRPA1, TRPC5, TRPV4, and TRPM8 gene expression levels were downregulated in the etoposide-resistant WERI-Rb1 cells. In the presence of extracellular Ca2+, 1 mM Asc induced larger intracellular Ca2+ transients in the etoposide-resistant WERI-Rb1 than in their etoposide-sensitive counterpart. With either 100 µM CPZ, 500 µM La3+, 10 mM NAC, or 100 µM 2-APB, these Ca2+ transients were markedly diminished. These inhibitors also had corresponding inhibitory effects on Asc-induced rises in whole-cell currents. Pertussis toxin (PTX) preincubation blocked rises in Ca2+ influx. Microscopic analyses showed that after 4 days of exposure to 1 mM Asc cell viability fell by nearly 100% in both RB cell lines. Taken together, one of the effects underlying oxidative mediated Asc-induced WERI-Rb1 cytotoxicity stems from its promotion of Gi/o coupled GPCR mediated increases in intracellular Ca2+ influx through TRP channels. Therefore, designing drugs targeting TRP channel modulation may be a viable approach to increase the efficacy of chemotherapeutic treatment of RB. Furthermore, Asc may be indicated as a possible supportive agent in anti-cancer therapies.
Funder
Karl und Charlotte Spohn Stiftung, Germany
Dr. Werner Jackstädt-Stiftung
KinderAugenKrebsStiftung
Deutsche Forschungsgemeinschaft
Sonnenfeld-Stiftung
Publisher
Springer Science and Business Media LLC
Subject
Cell Biology,Molecular Biology,Pathology and Forensic Medicine
Reference118 articles.
1. Dimaras H, Corson TW. Retinoblastoma, the visible CNS tumor: a review. J Neurosci Res. 2019;97:29–44.
2. Lohmann D, Gallie B, Dommering C, Gauthier-Villars M. Clinical utility gene card for: retinoblastoma. Eur J Hum Genet. 2011;19. https://doi.org/10.1038/ejhg.2010.200.
3. Dimaras H, Corson TW, Cobrinik D, White A, Zhao J, Munier FL, et al. Retinoblastoma. Nat Rev Dis Primers. 2015;1:15021.
4. Naseripour M. “Retinoblastoma survival disparity”: the expanding horizon in developing countries. Saudi J Ophthalmol. 2012;26:157–61.
5. Control UfIC. RETINOBLASTOMA. review of cancer medicines on the WHO list of essential medicines. WHO; 2014.https://www.who.int/selection_medicines/committees/expert/20/applications/Retinoblastoma.pdf?ua=1.
Cited by
17 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献