Expression of p63 and p73 in retinoblastoma: a clinicopathological correlation study

The aim of the study was to explore the expression profile of p63, p73 and their delta isoforms in the retinoblastoma tumor samples and to correlate with clinicopathological parameters. Immunohistochemistry was performed for p63, delta p63, p73 and delta p73 on the archival paraffin sections of retinoblastoma and correlated with clinicopathological features. Western blotting was performed to confirm immunoreactivity results. p63 immunoreactivity was observed in 59% (29/49) of the RB specimens. p63 was expressed in 60% (20/33) low risk tumors and in 56% (9/16) of high risk tumors. p73 was expressed in 77% (38/49) RB specimens. Among the 33 low risk tumors, p73 was expressed in 69% (23/33) tumors and among the 26 high risk tumors, p73 was expressed in 93% (15/16) tumors. High risk tumors showed significantly increased expression of p73 compared to tumors with low risk (P<0.05). This is the first correlation between p63/p73 expression and histopathology in human RB tumors. Our study showed increased expression of p73 in high risk tumors (P<0.05) compared to low risk tumors. Further functional studies are required to explore the role of p63, p73 and their respective isoforms in retinoblastoma.