Differential expression of the early lung cancer detection marker, heterogeneous nuclear ribonucleoprotein-A2/B1 (hnRNP-A2/B1) in normal breast and neoplastic breast cancer

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP-A2/B1) is highly expre ssed during critical stages of lung development and carcinogenesis. To dete rmine if the expression of hnRNP-A2/B1 is an informative biomarker in breas t carcinogenesis, we analyzed hnRNP-A2/B1 overexpression by immunohistochem istry in archived specimens. Expression was detected in 48/85 (56.5%) prima ry invasive breast cancers and 7/72 (9.7%) specimens of normal breast tissu e. Northern analysis of breast cancer cells also demonstrated higher level of hnRNP-A2/B1 expression compared to normal or transformed breast cells. E xpression of hnRNP-A2/B1 in breast cancer cells was decreased by exposure t o retinoids coordinately with decreased cell growth. These results warrant further evaluation of hnRNP-A2/B1 as a marker of breast carcinogenesis.