High frequency of retinoic acid receptor beta abnormalities in human lung cancer.

One of the three human retinoic acid receptors, RAR-beta, maps to a region on the short arm of chromosome 3 frequently deleted in lung cancer. Because retinoic acid is required for normal epithelial cell growth and regulation, and loss of a retinoic acid receptor might be expected to contribute to oncogenesis, we examined RAR-beta RNA and DNA in normal lung, 33 lung cancer cell lines and nine primary lung tumors. Normally, RAR-beta is expressed as two transcripts, of sizes 3.1 kb and 2.8 kb, which are strongly induced by retinoic acid. At least 50% of the cell lines and 30% of the tumor samples show altered RAR-beta expression and/or inducibility, including examples of absence or specific loss of one of the RAR-beta transcripts. Abnormalities in the expression patterns of RAR-alpha and RAR-gamma also are found, but at a lower frequency than RAR-beta abnormalities. Southern analysis reveals alteration of the RAR-beta gene in three of the cell lines. Our data suggest that abnormalities in structure and expression of the RAR-beta gene may be involved in the pathogenesis of lung cancer.