Abstract
Purpose :
This study extends our previous findings (Kim et al., 2021, Pflugers Arch - Eur J Physiol), which identified a small subset of larger 'giant' cells in human retinoblastoma Y79 cells, along with their functional expression of T-type calcium channels. We now aim to further explore these T-type channels, with a particular focus on the CaV3.3 subtype, to elucidate its role in the mechanisms of carboplatin resistance in these giant cells.
Methods :
We employed patch-clamp techniques, including current- and voltage-clamp experiments, to analyze the electrophysiological properties of Y79 cells. 'Regular' and 'giant' cells within the carboplatin-resistant Y79 (CR-Y79) phenotype were distinguished using K-means clustering, an unsupervised classification method based on cell size and resting membrane potential. To explore the association with the CaV3.3 subtype, we compared the calcium currents in these distinct cell populations and performed selective inhibition experiments using gene silencing and pharmacological methods.
Results :
Our findings revealed a significant increase in the proportion of 'giant' cells in the CR-Y79 phenotype. These cells exhibited a transient followed by a sustained calcium current, in contrast to the exclusively transient current observed in ‘regular’ cells. The presence of the sustained current, following the initial transient phase, was closely associated with the CaV3.3 subtype. Furthermore, our findings demonstrated that inhibiting CaV3.3 activity in CR-Y79 cells significantly increased their sensitivity to carboplatin, strongly indicating a critical role for CaV3.3 channels in the development of carboplatin resistance.
Conclusions :
These findings strongly suggest a link between the exclusive expression of CaV3.3 in ‘giant’ cells and their enhanced resistance to carboplatin. While further research is necessary, these results highlight the importance of calcium channels as potential therapeutic targets in carboplatin-resistant retinoblastoma. Our study lays the groundwork for future investigations into more effective treatments for retinoblastoma.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.