The human Cut gene, CUTL1, was mapped to chromosome 7, band 7q22, a region found in cytogenetic studies to be deleted in several human cancers. CUTL1 encodes for the human Cut protein, a homeodomain protein that was shown to bind to the promoter of the c-Myc proto-oncogene and repress its expression. As a first step in trying to determine whether CUTL1 is a tumor suppressor gene, we verified whether this gene is located within the chromosomal region that is deleted in human cancers. High resolution maps containing the CUTL1 genomic DNA were constructed in lambda phage, cosmid and PAC clones. Three (CA)n microsatellite polymorphic markers were identified within CUTL1 genomic DNA and were used in loss of heterozygosity (LOH) studies using genomic DNA from uterine leiomyomas and matched normal myometrium. LOH at 7q22 was demonstrated in 7 out 50 uterine leiomyomas samples, and the smallest commonly deleted region included CUTL1. Northern blot analysis revealed that CUTL1 mRNA levels were reduced in 8 out of 13 uterine leiomyomas. / In parallel studies, the Cut protein was found to interact with Polyomavirus large T (PyLT) protein in breast tumors and uterine leiomyomas that arise in transgenic mice expressing PyLT. Since LT was known to inactivate two tumor suppressors with which it interacts, Rb and p53, we hypothesized that genetic alterations to CUTL1 may occur in human breast cancers. Loss of heterozygosity at 7q22 was found in 18.2% (12/66) of sporadic breast tumors. The deleted region at 7q22 in every case included one or more of the three CUTL1 polymorphic markers. LOH at 7q22 was associated with increased tumor size, but not with tumor types and grades. / The exon-intron structure of CUTL1 was determined and several CUTL1 mRNA isoforms have been identified and characterized. All isoforms were found to be expressed in all tissues and tumor cells tested. Comparison of cDNA sequences with the CUTL1 genomic structure revealed a complex pattern of alternative transcription initiation, splicing and polyadenylation. Interestingly, transcription can starts in two genomic regions, and the choice between alternative polyadenylation sites and splice acceptor sites appears to be dictated by the nature of the first exon or associated promoter sequences.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35492 |
| Date | January 1998 |
| Creators | Zeng, Rong Wendy, 1968- |
| Contributors | Nepveu, Alain (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001652413, proquestno: NQ50284, Theses scanned by UMI/ProQuest. |
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