Shyra J. Crider-Miller, Ph.D.

Dissertation research performed under the guidence of Dr. Bernard E. Weissman

ABSTRACT
    The positional cloning approach to disease gene identification has made a significant impact in the search for tumor suppressor genes. Several lines of evidence, provided by genetic linkage analysis, loss of heterozygosity (LOH) studies, and functional assays, suggest the existence of a pediatric tumor suppressor gene on human chromosome 11p15.5. A variety of adult and childhood cancers have been linked to this region along with Beckwith-Wiedemann Syndrome (BWS), a congenital overgrowth disorder with predisposition to pediatric tumor development. Functional studies in pediatric tumor cell lines, RD and G401, have allowed us to narrow the critical region of tumor suppressor activity to a ~700 kb interval between D11S601 and D11S1318. Although candidate genes have been localized to this region, none has proven to be a true tumor suppressor. Therefore, we have continued the search for the tumor suppressor element in 11p15.5. Following the positional cloning protocol, a 1 Mb contig of genomic clones was created including the proposed critical region. To identify candidate tumor suppressor genes in 11p15.5, cDNA fragments were isolated in four rounds of solution hybrid capture with six genomic clones covering most of the region between D11S601 and D11S1318. These experiments resulted in the identification often novel genes, most of which display tissue-specific expression patterns. Although none of these genes appeared to be responsible for tumor suppression in G401 cells, the tissue-specific expression patterns observed with these genes correlate well with the pediatric cancer types associated with alterations in 11p15.5. Isolation of full-length cDNA clones and further characterization of these genes, including expression analysis, mutational analysis, imprinting status, and developmental studies, will result in significant progress toward the understanding of genetic alterations involved in BWS and human cancers. Preliminary characterization of the three genes with skeletal muscle-specific transcripts in rhabdomyosarcoma (RMS) cell lines implicated these genes in the development of this tumor type, warranting further investigation.