A Molecular Cytogenetic Study of Chromosome 3 Rearrangements in Small Cell Lung Cancer: Consistent Involvement of Chromosome Band 3q13.2

To more precisely determine the nature of chromosome 3 rearrangements in small cell lung carcinomas (SCLCs), we have applied molecular cytogenetic technologies to a newly characterized SCLC tumor and five SCLC cell lines. Fluorescent in situ hybridization, chromosome microdissection, and, on the previously uncharacterized tumor, spectral karyotyping was utilized to determine chromosome 3 rearrangements. In all cases, our studies were performed on previously G-banded chromosomes in a sequential manner to facilitate a direct comparison. A consistent breakpoint on the long arm of chromosome 3 at band 3q13.2 was identified in all six tumors. This breakpoint was commonly the result of complex chromosomal rearrangements. Loss of the entire short arm of a chromosome 3 was noted in all six tumor cultures. Two of these cell lines had two sublines, one of which contained a 3q13.2 rearrangement and the other of which contained a chromosome rearrangement that resulted in loss of a chromosome 3 short arm. This consistent rearrangement at chromosome band 3q13.2, as demonstrated by molecular cytogenetic methods, may indicate the location of a gene important in the tumorigenesis of SCLC.