Biomedical subjects

Gregg Magrane

Publications and source records attributed to Gregg Magrane.

3 recordsLinked to original sources

PubMed2003

End-sequence profiling: sequence-based analysis of aberrant genomes.

Genome rearrangements are important in evolution, cancer, and other diseases. Precise mapping of the rearrangements is essential for identification of the involved genes, and many techniques have been developed for this purpose. We show here that end-sequence profiling (ESP) is particularly well suited to this purpose. ESP is accomplished by constructing a bacterial artificial chromosome (BAC) library from a test genome, measuring BAC end sequences, and mapping end-sequence pairs onto the normal genome sequence. Plots of BAC end-sequences density identify copy number abnormalities at high resolution. BACs spanning structural aberrations have end pairs that map abnormally far apart on the normal genome sequence. These pairs can then be sequenced to determine the involved genes and breakpoint sequences. ESP analysis of the breast cancer cell line MCF-7 demonstrated its utility for analysis of complex genomes. End sequencing of approximately 8,000 clones (0.37-fold haploid genome clonal coverage) produced a comprehensive genome copy number map of the MCF-7 genome at better than 300-kb resolution and identified 381 genome breakpoints, a subset of which was verified by fluorescence in situ hybridization mapping and sequencing.

Animals↗

PubMed2003

Chromosomal aberrations by comparative genomic hybridization in thyroid tumors in patients with familial nonmedullary thyroid cancer.

PURPOSE: Nonmedullary thyroid cancer is the most common form of thyroid cancer and its familial form (FNMTC) is increasingly recognized as a distinct clinical entity. However, the genetic background of FNMTC is still poorly understood and the causative gene(s) have not yet been identified. METHODS: Because comparative genomic hybridization allows for screening of the entire tumor genome simultaneously for chromosomal gains and/or losses without prior knowledge of potential aberrations, we used this technique in thyroid normal and neoplastic samples from FNMTC patients (1) to analyze whether chromosomal aberrations would correlate with inheritance pattern, and/or clinicopathologic features and (2) to compare comparative genomic hybridization (CGH) findings in familial tumors with those already known in sporadic differentiated thyroid cancers. RESULTS: No common germline or somatic chromosomal aberrations were observed in patients with FNMTC because the frequencies and most locations of chromosomal aberrations in familial tumors were also common in sporadic tumors. However, some somatic aberrations were only found in familial tumors (gains in 2q, 3q, 18p, and 19p). Common aberrations in familial tumors corresponded to several locations of candidate genes already reported for sporadic thyroid tumorigenesis. CONCLUSIONS: Our findings suggest that chromosomal aberrations in thyroid tumors in patients with FNMTC are not related to inheritance pattern but rather to tumorigenesis.

Adolescent↗

PubMed2003

Characterization and chromosomal instability of novel derived cell lines from a wt-erbB-2 transgenic mouse model.

Amplification and overexpression of the erbB-2 (HER-2/neu) proto-oncogene and exposure to the cell cycle mitogenic hormone estrogen (E2) have been associated with mammary tumorigenesis. Phytoestrogens found in soy act as selective estrogen receptor modulators and may also modify mammary carcinogenesis. We have used the wt-erbB-2 transgenic mouse model to study the effects of estrogen and dietary phytoestrogens on erbB-2-associated mammary tumorigenesis. Transgenic mice were treated with short-term E2 or placebo pellets during the early reproductive period and fed a casein or soy diet for life. Mammary tumors from the different treatment groups were used for the derivation of novel cell lines. Comparative genomic hybridization (CGH), flow cytometry, assays of cell proliferation and soft agar cloning were performed to study genomic instability and in vitro characteristics. CGH data were compared with corresponding parental tumors. Mammary tumors exhibited significantly fewer genetic changes than cell lines by CGH. Cell lines from soy-fed animals (that developed tumors with a longer latency) demonstrated the greatest frequency of chromosomal gain and loss. The E2-treated, casein-fed animals (that developed tumors with the shortest latency) had the fewest genetic changes in derived lines by CGH. Nonetheless, E2-associated tumors in vivo and lines in vitro had the most aggressive phenotypes. In addition, over 40% of all derived cell lines, and both tumors from the placebo-treated casein-fed mice, exhibited loss of chromosome 4 by CGH. In aggregate, our data suggest that estrogenic signaling influences mammary tumor development in this transgenic mouse model bearing the rat wt-erbB-2 gene. Once induced, tumors and derived lines demonstrate persistent phenotypic characteristics, including tumor aggression and shortened latency in E2-treated mice. Loss of chromosome 4 was commonly identified in derived lines and may have facilitated immortalization or passage in culture.

Animals↗