Expression of hnRNP B1 in four major histological types of lung cancers

Heterogeneous nuclear ribonucleoprotein B1 is one of the nuclear pre-mRNA b inding proteins involved in RNA metabolism. Recently, over-expression of B1 has been reported to be useful in the early detection of squamous cell car cinomas of the lung. To elucidate its significance in other histological ty pes of lung cancers, we carried out a comparative study, four major types o f lung cancers and normal lung tissues. 37 surgical specimens were examined using a BI-specific monoclonal antibody (2B2). Immunohistochemically, 2B2 demonstrated BI protein in the nuclei not only of squamous cell carcinoma ( 10/10) but also of adenocarcinoma (17/18), small cell carcinoma (5/5) and l arge cell carcinoma (3/4). A lesser amount of BI protein was also detected in normal cells. Quantitative immunoblotting revealed that BI expression wa s markedly higher in cancer tissues than normal tissues and it varied among the four histological types. To establish the usefulness of B1, a threshol d should be set far over-expression.