Regulation of cathepsin D gene expression in human breast cancer cells /
17P-Estradiol (E2) induces cathepsin D gene expression in
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=736554711&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | 17P-Estradiol (E2) induces cathepsin D gene expression in MCF-7 human breast cancer cells. Analysis of 5'-promoter region of cathepsin D gene identified a CGCCC(N)3TGACC sequence (-119 to -107) which is homologous to the adenovirus major late promoter element (MLPE) and binds to the ER to form a retarded band in a gel eletrophoretic mobility shift assay. The corresponding promoter-CAT construct is also E2 inducible. Additional inspection of upstream regions from the MLPE identified another E2responsive element which contains two overlapping Spl binding sites (5'CCGCCCCGCCC-3') at -145 to -135. Gel mobility shift assays using 32p labeled oligonucleotide containing the two overlapping Spl sites ([12p]CD/L) showed that Spl formed a DNA-protein complex and intensities of the retarded bands were enhanced by coincubation with the ER. The corresponding promoter-CAT (pCD/L) was also E2inducible in MCF-7 cells or ER-negative MDA-MB-231 cells cotransfected with wild-type ER or 1 1C-ER (without DNA binding domain). Interestingly, a DRE (dioxin responsive element) at -130 to -126 is demonstrated to be involved in the basal and E2-activated cathepsin D gene expression, and acted as an inhibitory DRE (IDRE) to inhibit E2-induced cathepsin D expression by TCDD. Recent studies show that growth factors such as EGF and IGF-I can increase cathepsin D gene expression. Treatment with EGF, IGF-I and TGF(X increased CAT activity in MCF-7 cells transiently transfected with pCD2.74k containing the cathepsin D gene promoter from -2576 to - 124. However, only IGF-I significantly increased CAT activity in cells transiently transfected with pCD2 containing cathepsin D gene promoter from -208 to - 1 0 1. Further transient transfection assays utilizing pCd, pCD/L and pCD/R (containing cathepsin D gene promoter from -208 to - 1 61, -145 to - 1 19, -120 to - I 0 1, respectively) showed that the three E2-responsive regions are also IGF-1-inducible and mutations of the E2-responsive @PE (- 1 19 to - 107) and two overlapping Sp 1 sites (- 145 to -135) significantly decreased CAT activity. These results suggest that IGF-mediated transactivation pathway may crosstalk with ER-mediated pathway for cathepsin D gene expression. |
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| Item Description: | Vita. "Major Subject: Toxicology". |
| Physical Description: | xiii, 191 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 148-190. |