Characterization of a Novel Breast Carcinoma Xenograft and Cell Line Derived from a BRCA1 Germ-Line Mutation Carrier

Abstract

SUMMARY:A human tumor xenograft (L56Br-X1) was established from a breast cancer axillary lymph node metastasis of a 53-year-old woman with a BRCA1 germ-line nonsense mutation (1806CϾT; Q563X), and a cell line (L56Br-C1) was subsequently derived from the xenograft. The xenograft carries only the mutant BRCA1 allele and expresses mutant BRCA1 mRNA but no BRCA1 protein as determined by immunoprecipitation or Western blotting. The primary tumor, lymph node metastasis, and xenograft were hypodiploid by DNA flow cytometry, whereas the cell line displayed an aneuploidy apparently developed via polyploidization. Cytogenetic analysis, spectral karyotyping, and comparative genomic hybridization of the cell line revealed a highly complex karyotype with numerous unbalanced translocations. The xenograft and cell line had retained a somatic TP53 missense mutation (S215I) originating from the primary tumors, as well as a lack of immunohistochemically detectable expression of steroid hormone receptors, epidermal growth factor receptor, human epidermal growth factor receptor 2 (HER-2), and keratin 8. Global gene expression analysis by cDNA microarrays supported a correlation between the expression profiles of the primary tumor, lymph node metastasis, xenograft, and cell line. We conclude that L56Br-X1 and L56Br-C1 are useful model systems for studies of the pathogenesis and new therapeutic modalities of BRCA1-induced human breast cancer. (Lab Invest 2003, 83:387-396).

Aurora-A gene is frequently amplified in basal-like breast cancer

“…Breast cancer cell line L56Br-C1 deficient in BRCA1 gene product was kindly provided by Professor Åke Borg, University of Lund, Sweden (11). Breast cancer cell line clinically resistant to trastuzumab (Herceptin) JIMT-1 was established and characterized in our laboratory (12) and is available via DSMZ (www.dsmz.de).…”

“…Breast cancer cell line clinically resistant to trastuzumab (Herceptin) JIMT-1 was established and characterized in our laboratory (12) and is available via DSMZ (www.dsmz.de). All the breast cancer cell lines used in this study were cultured in recommended conditions and DNA, RNA and protein extraction were done using standard procedures (11).…”

Numb protein expression correlates with a basal-like phenotype and cancer stem cell markers in primary breast cancer

“…All cell lines except for L56Br-C1, JIMT-1 and PMC42 were obtained from the American Type Culture Collection (ATCC, Rockville, MD). L56Br-C1 was established at Lund University [9], and JIMT-1 was established at Tampere University [10,11] and purchased from the German Collection of Microorganisms and Cell Cultures (DSMZ, Braunschweig, Germany). PMC42 was received through a generous donation from Dr. Anna Git at the Breast Cancer Functional Genomics Laboratory, Cancer Research UK, Cambridge Research Institute and Department of Oncology, University of Cambridge, UK.…”

Dysfunctional BRCA1 is only indirectly linked to multiple centrosomes

“…In mitotic MCF-7 cells, the D9 (a, d) and C20 (e, h, arrows) antibodies colocalize with centrosomes, although the C20 antibody shows some background staining. Although L56Br-C1 cells do not express BRCA1 protein (Johannsson et al, 2003), the D9 (i, l) and the C20 (m, p, arrows) antibodies do localize to the centrosomes comparable to the centrosomal localization in MCF-7 cells. Bar, 10 mm cells (Dodson et al, 2004), or during mitosis in the presence of incompletely replicated DNA (Hut et al, 2003).…”

“…In combination with the fact that EGFP-BRCA1 and BF3-GFP do not localize to centrosomes, this suggests that BRCA1 antibodies nonspecifically bind to centrosomes after methanol fixation. To test this further, we used L56Br-C1 cells that do not express endogenous BRCA1 (Johannsson et al, 2003). Indeed, after paraformaldehyde/methanol fixation, a pronounced D9 and C20 antibody labeling was present at centrosomes of mitotic L56Br-C1 cells (Figure 2i-p).…”