6764

ST5

DENND2B|HTS1|p126;suppression of tumorigenicity 5;ST5;suppression of tumorigenicity 5

DENN/MADD domain containing 2B|heLa tumor suppression 1|suppression of tumorigenicity 5 protein

11p15

protein-coding

The tumorigenicity of HeLa cells in nude mice can be suppressed by the addition of a normal human chromosome 11 in somatic cell hybrids. We have attempted to identify specific genes involved in this phenomenon by transfecting a complementary DNA expression library into a tumorigenic HeLa-fibroblast hybrid. A cell line designated F2 was isolated which displayed morphological features of the nontumorigenic hybrids, demonstrated reduced tumorigenicity in nude mice, and showed an 85% reduction in alkaline phosphatase, a consistent marker of the tumorigenic phenotype in these cells. F2 contained a single exogenous complementary DNA, which was recovered by polymerase chain reaction and designated HTS1 because of its potential association with "HeLa tumor suppression." Northern blot studies suggested differential regulation of the HTS1 gene dependent on the tumorigenicity of the cell. In nontumorigenic hybrids, RNA species of 2.8, 3.1, and 4.6 kilobases were identified. In two tumorigenic hybrid lines, the 2.8-kilobase species was markedly reduced or absent. Similarly, three nontumorigenic human keratinocyte lines expressed all three RNA species, whereas several tumorigenic cervical carcinoma cell lines lacked the 2.8-kilobase species. Chromosome localization studies mapped the HTS1 gene to chromosome 11p15, a region of chromosome 11 that is believed to contain a tumor suppressor gene. These findings indicate that HTS1 represents a novel chromosome 11 gene which may be a target of the tumor suppressor gene active in this system.

Non-small-cell lung cancer is the leading cause of cancer death for men and women in the industrialized nations. Identification of regions for genes involved in its pathogenesis has been difficult. Data presented here show three distinct regions identified on chromosome 11p. Two regions on 11p13 distal to the Wilms tumor gene WT1 and on 11p15.5 between the markers HBB and D11S860 are described. The third region on the telomere of 11p15.5 has been previously described and is further delineated in this communication. By high-resolution mapping the size of each of these regions was estimated to be 2-3 megabases. The frequency of somatic loss of genetic information in these regions (57%, 71%, and 45%, respectively) was comparable to that seen in heritable tumors such as Wilms tumor (55%) and retinoblastoma (70%) and suggests their involvement in pathogenesis of non-small-cell lung cancer. gene dosage analyses revealed duplication of the remaining allele in the majority of cases in the 11p13 and the proximal 11p15.5 region but rarely in the distal 11p15.5 region. In tumors with loss of heterozygosity in all three regions any combination of duplication or simple deletion was observed, suggesting that loss of heterozygosity occurs independently and perhaps at different points in time. These results provide a basis for studies directed at cloning potential tumor-suppressor genes in these regions and for assessing their biological and clinical significance in non-small-cell lung cancer.