Abstract
Purpose :
Apoptosis and ferroptosis are two distinct forms of cell death with different mechanisms and implications in cancer. Our previous study showed that damaged mitochondria, increased expression of BAX/BCL2, and mitochondria complex I loss were common in retinoblastoma (Rb) tumours. These findings prompted us to conclude that, in addition to apoptosis, a non-apoptotic cell death known as ferroptosis could be pertinent. Therefore, the purpose of this study is to investigate the morphological, pathological, and molecular implications of apoptosis and ferroptosis mechanism in Rb patients.
Methods :
A total of 123 prospective cases were included among which 82 cases underwent primary enucleation and 41 cases received chemotherapy/radiotherapy before enucleation (chemoreduced Rb). Transmission electron microscopy (TEM) was performed to observe ultrastructural changes. Immunohistochemistry was done for Transferrin receptor (TFR1) and caspases protein on formalin-fixed paraffin embedded tissues. mRNA expression level was measured for apoptosis (Caspases 3, 8 and 9 genes) and ferroptosis-related genes (SLC7A11, SLC3A2, GPX4) using qRT-PCR and correlated with clinicopathological parameters and patient survival.
Results :
There was male preponderance with more than 50% of the cases belong to <2 years of age. Massive choroidal invasion was the most frequent histopathological parameter in primary Rb. Necrosis and calcification were found mostly in chemoreduced Rb cases. TEM showed morphological features of cell death that corresponds more to ferroptosis than apoptosis. Upregulated mRNA expression of Caspase-3 and -8 was found in 85% and 72.5% cases, respectively. Downregulation of Caspases-9 was found in 70% of the cases, and this was statistically significant with massive choroidal invasion (p<0.05). Cytoplasmic expression of TFR1 protein was found in 78% cases. Scleral invasion was statistically significant with TFR1 expression and upregulated GPX4 level (p<0.05).
Conclusions :
This study showed that the differential expression of apoptosis and ferrotosis-regulated genes could predict the tumorigenesis of Rb. Therefore, finding a balance between ferroptosis and apoptosis may be critical for gaining a better understanding of Rb progression and developing effective therapeutic options for clinical benefits.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.