Abstract
Purpose:
Our study compares the clinical classification of retinoblastoma (Rb) with histopathological risk in enucleated eyes and attempts to identify a gene expression pattern that shows unique correlation to each group.
Methods:
We retrospectively studied 58 enucleated eyes with intraocular Rb, and excluded 19 eyes that had received pre-enucleation chemotherapy or focal therapy. Classification at presentation was determined using the IIRC system for the 39 eyes included. We collected 9 fresh frozen tumor samples and subjected them to microarray analysis to define gene expression patterns. Written, informed consent and approval of the Institutional Ethics Committee was obtained prior to sample collection.
Results:
Of the 39 eyes, 18 had high-risk pathology. When the group was sub-classified using the IIRC classification, 1/7 Group D eyes and 17/32 Group E eyes had high-risk pathology. Using this classification, we determined the global gene expression patterns from 2 Group D and 7 Group E eyes with differential risk scores. Based on this categorization, 1027 and 2633 genes were associated with Group E and Group D eyes respectively (p≤0.05 and fold change≥2). When the stringency was raised to fold change>10, the Group E eye with high-risk pathology had 108 unique deregulated transcripts compared to 473 for the Group D eyes without high-risk pathology. Pathway analysis performed with the differentially expressed genes revealed predominant pathways like EGFR signaling, androgen receptor signaling, proteasome degradation and electron transport chain, in the Group E eyes with high-risk pathology,. Amongst the most highly deregulated genes, the E2F family, SYK, CD86 and CDC20 were expressed at significantly higher levels in the Group E eyes with high-risk pathology, while RDH12 was most downregulated.
Conclusions:
Clinical and pathological risk criteria may not always correlate, but a gene expression signature for differential risk groups was discovered. The data illustrate a molecular pattern that correlates with clinical high risk in Rb patients and may provide some novel clues for management.