Cathepsin D gene is controlled by a mixed promoter, and estrogens stimulate only TATA-dependent transcription in breast cancer cells.
The cathepsin D (cath-D) gene, coding for a ubiquitous lysosomal aspartyl protease, is overexpressed in aggressive human breast cancers, and its transcription is induced by estrogens in hormone-responsive breast cancer cells. We have determined the structure and function of the proximal 5' upstream region of the human cath-D gene from MCF7 cells. We show that the promoter has a compound structure with features of both housekeeping genes (high G+C content and potential transcription factor Sp1 sites) and regulated genes (TATAA sequence). By RNase protection assay, we show that transcription is initiated at five major transcription sites (TSSI to -V) spanning 52 base pairs. In hormone-responsive breast cancer cells, estradiol increased by 6- to 10-fold the level of RNAs initiated at TSSI, which is located about 28 base pairs downstream from the TATA box. The specific regulation by estradiol of transcription starting at site I exclusively was confirmed by primer extension. Moreover, the same estradiol effect was observed in the ZR75-1 cell line and in MDA-MB231 estrogen-resistant breast cancer cells stably transfected with the estrogen receptor. Site-directed mutagenesis indicated that the TATA box is essential for initiation of cath-D gene transcription at TSSI. In breast cancer biopsy samples, high levels of TATA-dependent transcription were correlated with overexpression of cath-D mRNA. We conclude that cath-D behaves, depending on the conditions, as a housekeeping gene with multiple start sites or as a hormone-regulated gene that can be controlled from its TATA box.
Cavaillès
V
V
Institut National de la Santé et de la Recherche Médicale, U 148, Unit Hormones and Cancer, Montpellier, France.
Augereau
P
P
Rochefort
H
H
D000818:Animals; D016375:Antisense Elements (Genetics); D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics*; D002402:Cathepsin D / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D004958:Estradiol / Q000494:pharmacology*; D005091:Exons; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D015347:RNA Probes; D051381:Rats; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D016385:TATA Box; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
D016375:Antisense Elements (Genetics); D004273:DNA, Neoplasm; D015347:RNA Probes; D004958:Estradiol; D004247:DNA; D002402:Cathepsin D