Cell Growth & Differentiation, Vol 6, Issue 9 1097-1102, Copyright © 1995 by American Association of Cancer Research

ARTICLES

Regulation of ornithine decarboxylase mRNA levels in human breast cancer cells: pattern of expression and involvement of core enhancer promoter element

PS Wright, JR Cooper, DE Cross-Doersen, JA Miller, PA Chmielewski, RL Wagner, KA Streng and MA Flanagan
Marion Merrell Dow Research Institute, Cincinnati, Ohio 45215-6300, USA.

Ornithine decarboxylase (ODC) expression is increased by growth factors and is obligatory for progression through the cell cycle in a wide variety of cell types. In this study, a variant human ODC cDNA was identified, sequenced, and used to probe mRNA levels in human breast tumor cell lines and xenografts. ODC mRNA was elevated about 3-fold in estrogen receptor-negative (ER-) tumors (MDA-MB-231) when compared with ER-positive (ER+) tumors (MCF-7), as assessed by quantitative autoradiographic analysis of in situ hybridization experiments. The pattern of ODC mRNA in MDA-MB-231 (ER-) xenografts was polarized to the extreme periphery of the tumor, whereas the distribution of ODC mRNA was more evenly distributed in MCF-7 (ER+) xenografts. This correlates with hematoxylin and eosin staining patterns, suggesting that ER+ and ER- xenografts have a differential dependence on host vasculature for growth factor supply. ODC mRNA was elevated 5-fold in MDA-MB-231 cells versus MCF-7 cells when analyzed in cell culture. These relative mRNA levels correlate with increased levels of "core" enhancer binding nuclear proteins in MDA-MB-231 cells over that detected in MCF-7 cells.

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