Clonal dominance detected in metastases but not primary tumors of retrovirally marked human breast carcinoma injected into nude mice

Abstract

Human breast cancer cell lines which grow in athymic (nude) mice provide a model of tumor cell growth and metastasis. Marking transplanted tumor cell populations with retroviral vectors provides a means of studying the dynamics of tumor cell growth in vivo. We evaluated three human breast cancer cell lines, MDA-MB-435, MDA-MB-231 and MCF-7, and found the cells were highly susceptible to retroviral gene transfer after a single 2-h exposure (90.9%, 62.7% and 72.3%, respectively). MDA-MB-435 cells (5 x 10(5)) marked with a retroviral vector containing the beta-galactosidase gene (approximately 10(4) uniquely marked clones) were injected into the mammary fat pad of athymic mice to study clonal dominance. Primary tumors resected 10 weeks after injection expressed beta-galactosidase, demonstrating persistent vector expression in vivo. Southern blot analysis did not reveal clonal dominance in the primary tumors of the five mice studied. In contrast, pulmonary metastases in each animal were monoclonal or biclonal. These results demonstrate clonal dominance in pulmonary metastases but not primary tumors of retrovirally marked MDA-MB-435 cells. Our findings suggest that this model may also be used to introduce retroviral vectors expressing oncogenes, and anti-sense oncogenes, to determine their effect on tumor cell proliferation and metastasis in vivo.

Integrin activation controls metastasis in human breast cancer

“…Our data are consistent with the idea that tumor cells expressing platelet-interactive ␣v␤3 are present in the parental MDA-MB 435 cell line at a low frequency and that these were selected in vivo during tumor growth and metastasis. The MDA-MB 435 cell line is a polyclonal cell population, but its variants derived from distant metastases in mice are oligo-or monoclonal (26). We therefore asked whether cells expressing the platelet-interactive phenotype are present in the parental MDA-MB 435 parental cell population and can be isolated in vitro based on their ability to undergo platelet-mediated arrest during blood flow.…”

Effects of HIV Protease Inhibitor Ritonavir on Akt-Regulated Cell Proliferation in Breast Cancer

“…The mice were female nude mice (nu À/À ) 6 to 8 weeks old (Harlan, Indianapolis, IN). For xenograft studies, 1 Â 10 6 log-phase MDA-MB-231 tumor cells were injected into the right mammary fat pad using an established method (24,25). Tumor volume was calculated by the well-known formula: volume (mm 3 ) = (length) (width) 2 / 2.…”

Negative Regulation of Transactivation Function but Not DNA Binding of NF-κB and AP-1 by IκBβ1 in Breast Cancer Cells

“…Retrovirus Preparation and Transduction-LxSN vectors were amphotrophically packaged into the AM12 packaging cell line (33), and the cell-free supernatant was used to transduce MDA-MB-231 cells as described previously (34). Vector containing clones were isolated by growing cells in G418 (1 mg/ml).…”