Significance of Heterogeneous Nuclear Ribonucleoprotein B1 as a New Early Detection Marker for Oral Squamous Cell Carcinoma

The development of an early tumor detection marker for oral cancer is an obvious need due to the high recurrence rate and poor survival rate. Based on our previous report that overexpression of heterogeneous nuclear ribonucleoprotein (hnRNP) B1 protein was found in 100% of squamous cell carcinomas of human lung, we applied the same immunohistochemical method, using anti‐hnRNP B1 antibody, to human oral squamous cell carcinoma (OSCC). Seven human tissue sections of OSCC showed strong staining with anti‐hnRNP B1 antibody, and hnRNP B1 protein of 37 kDa was identified in protein fractions isolated from six of the cancerous tissue sections, while it was not found in adjacent noncancerous tissue. Moreover, three non‐homogeneous (nodular) leukoplakia sections showed significant anti‐hnRNP B1 staining. The results suggest that this antibody detects precancerous lesions as well as advanced lesions (stages I to IV) of OSCC. We also present positive results of cytodiagnosis for two smear specimens. All of the above results indicate that hnRNP B1 is a new and useful marker for early detection of OSCC.