Heterogeneous nuclear ribonucleoprotein B1 expressed in esophageal squamous cell carcinomas as a new biomarker for diagnosis

We recently reported that heterogeneous nuclear ribonucleoprotein (hnRNP) B 1 was overexpressed in most human lung cancers, especially squamous cell ca rcinoma (SCC), as well as human oral SCC, To find the significance of hnRNP BI in cancer diagnosis, ne studied hnRNP B1 expression in 16 paraffinized sections of esophageal SCC, using immunohistochemical staining with anti-hn RNP BI polyclonal antibody, raised in a rabbit. We compared the expression of hnRNP B1 in cancerous and noncancerous regions of the same specimen: enh anced expression nas observed in 63% of cancerous regions (10/16), whereas none of the noncancerous regions showed enhanced expression. The enhanced e xpression of hnRNP B1 in cancerous regions was compared with that in noncan cerous tissue in relation to histopathological grade: 83% for well differen tiated (5/6), 83% for moderately differentiated (5/6) and 0% for poorly dif ferentiated (0/4). Histologically, enhanced expression of hnRNP BI was obse rved around cancer pearls, as well as in the cells of nests lacking keratin ization in well and moderately differentiated SCC, Western blotting analysi s revealed enhanced expression in three frozen specimens of moderately diff erentiated SCC, Using esophageal cancer cell lines, we further confirmed th e decreased expression in poorly differentiated SCC cells, compared with ot her differentiation types. All our results support the significance of hnRN P B1 expression in esophageal SCC as a unique diagnostic marker with regard to association between expression level and histopathological grading.