Expression of high mobility group A2 protein in retinoblastoma and its association with clinicopathologic features

Summary: Retinoblastoma (RB) is the commonest primaryintraocular tumor in children. Overexpression of the high mobilitygroup (HMG) A2 protein has been observed in a variety ofmalignant tumors and often correlates with poor prognosis. Westudied the expression of HMGA2 in primary tumor samples andcorrelated with clinicopathologic features such as invasion,differentiation, and laterality of the tumors. Among 64 tumors,there were 29 tumors with invasion of the optic nerve, choroid,and/or orbit and 35 tumors without invasion. HMGA2 immuno-reactivity was evaluated on archival paraffin sections and theresults confirmed by Western blotting on 12 fresh tumor samples.Among 29 tumors with invasion, HMGA2 was strongly positive(++) in 10 tumors, moderately positive (+) in 11 tumors. Among35 tumors without invasion, HMGA2 was strongly positive (++)in 6 tumors, moderately positive (+) in 6 tumors. Tumorswith invasion showed significantly higher expression of HMGA2compared with tumors without invasion (P