Deletion of three distinct regions on chromosome 13q in human non-small-cell lung cancer

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Abstract
We examined loss of heterozygosity (LOH) at the retinoblastoma susceptibility gene (RBI) locus on chromosome 13q14 in 20 non-small-cell lung cancers (NSCLCs) using polymorphic markers. The expression of RB protein was examined by immunohistochemical analysis of paraffin-embedded specimens of the same tumors. The results revealed that 10 of 16 informative cases showed an LOH at the RBI locus, whereas only 2 of the 10 tumors lost expression of the RB protein. These 2 tumors had mutations in the remaining RBI allele. Thus, inactivation of the RBI gene appears to be involved in a small subset of NSCLCs only. To elucidate the presence of tumor-suppressor genes other than RBI on 13q, heterozygosity at 15 different loci was investigated. Of 20 tumors analyzed, 15 showed an LOH at least at one locus, and the regions 13q12.1-qter, 13q12.2–14.2 and 13q14.1–q14.3, including the RBI locus, were deleted in significant numbers of the tumors. Our results suggest that, in addition to the RBI gene, abnormalities of other tumor-suppressor genes on chromosome 13q are involved in the development of human NSCLCs. Int. J. Cancer 74:45–49. © 1997 Wiley-Liss, Inc.