fur gene expression as a discriminating marker for small cell and nonsmall cell lung carcinomas.

The recently discovered fur gene encodes a membrane-associated protein with a recognition function. To further characterize the gene, we studied its expression by Northern blot analysis using poly(A)-selected RNA from a variety of organs of African green monkey and rat. The fur gene appeared to be differentially expressed, relatively high levels of fur mRNA being present in specimens of liver and kidney, low levels in brain, spleen, and thymus, and very low levels in heart muscle, lung, and testis. mRNA levels in specimens of human lung tissue without neoplastic lesions were also very low. Similar analyses of primary human lung carcinomas of different histopathological types revealed a highly selective and strong elevation of fur expression in nonsmall cell lung carcinomas, but not in small cell lung carcinomas. These results indicate that fur expression can be used to discriminate between these two types of human lung cancer.