Abstract
Purpose :
The diverse role of exosome specific protein CD9 in tumor progression and tumor suppression as well as in metastasis have been documented in various cancers. However, the functional role of CD9 in pediatric cancer retinoblastoma (RB) is not much explored. The aim of the present study was to explore the CD9 expression in RB and assess the expression in eyes with histopathological features predictive of metastasis.
Methods :
A retrospective observational study was performed on clinically diagnosed and enucleated globes of RB. These cases were categorized into two groups low-risk group (n=12) and high-risk group (n=13) based on histopathological features. Formalin fixed paraffin embedded sections were stained with anti CD9 antibody (Santa Cruz, Texas, USA) and assessed for protein expression pattern, intensity and location in the sections were correlated with tumor pattern, differentiation, tumor invasion into adjacent structures and pathological TNM staging.
Results :
We noted low to moderate expression of CD 9 in the less differentiated tumors in comparison to highly differentiated tumors in both the groups. In the high-risk group, four (33.3%) eyes harbored poorly to undifferentiated tumor morphology and higher pathological stage showed increased protein expression in the areas of invasion. Strong expression was noted in apoptotic cells, retinocytoma areas and new blood vessels. Increased CD 9 expression was noted in the normal intra-ocular structures including retinal ganglionic cell, inner and outer plexiform layer, and optic nerve.
Conclusions :
CD 9 expression increased with decreasing level of cellular differentiation and higher TNM stage. This study suggests that there is correlation between the exosomal specific marker CD9 and histopathological features. The clinical relevance of the same needs to be explored.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.