Progression of colorectal cancer is associated with multiple tumor suppressor gene defects but inhibition of tumorigenicity is accomplished by correction of any single defect via chromosome transfer
- Univ. of California, Irvine (United States)
- John Hopkins Univ. School of Medicine and Hospital, Baltimore, MD (United States)
- Univ. of Bristol, University Walk, Bristol (United Kingdom)
Colorectal cancer has been associated with the activation of ras oncogenes and with the deletion of multiple chromosomal regions including chromosomes 5q, 17p, and 18q. The candidate tumor suppressor genes from these regions are, respectively, MCC and/or APC, p53, and DCC. In order to further understanding of the molecular and genetic mechanisms involved in tumor progression and, thereby, of normal cell growth, it is important to determine whether defects in one or more of these loci contribute functionally in the progression to malignancy in colorectal cancer and whether correction of any of these defects restores normal growth control in vitro and in vivo. To address this question, the authors have utilized the technique of microcell-mediated chromosome transfer to introduce normal human chromosomes 5, 17, and 18 individually into recipient colorectal cancer cells. Additionally, chromosome 15 was introduced into SW480 cells as an irrelevant control chromosome. While the introduction of chromosome 17 into the tumorigenic colorectal cell line SW480 yielded no viable clones, cell lines were established after the introduction of chromosomes 15, 5, and 18. SW480-chromosome 5 hybrids are strongly suppressed for tumorigenicity, while SW480-chromosome 18 hybrids produce slowly growing tumors in some of the animals injected. Hybrids containing the introduced chromosome 5 express the APC gene present on that chromosome as well as the endogenous mutant transcript. Expression of the putative tumor suppressor gene, DCC, was seen in the clones containing the introduced chromosome 18 but was significantly reduced in several of the tumor reconstitute cell lines. Our findings indicate that while multiple defects in tumor suppressor genes seem to be required for progression to the malignant state in colorectal cancer, correction of only a single defect can have significant effects in vivo and/or in vitro.
- OSTI ID:
- 7172916
- Journal Information:
- Molecular and Cellular Biology; (United States), Vol. 12:3; ISSN 0270-7306
- Country of Publication:
- United States
- Language:
- English
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