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Induction of transforming growth factor-beta receptor type II expression in estrogen receptor-positive breast cancer cells through SP1 activation by 5-aza-2'-deoxycytidine.
J Biol Chem. 1998 Jun 26; 273(26):16527-34.JB

Abstract

Previous studies suggest that estrogen receptor-positive (ER+) breast cancer cells acquire resistance to transforming growth factor-beta (TGF-beta) because of reduced expression levels of TGF-beta receptor type II (RII). We now report that treatment of ER+ breast cancer cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-2'-dC) leads to accumulation of RII transcript and protein in three different cell lines. RII induction restored TGF-beta response in MCF-7L breast cancer cells as indicated by the enhanced activity of a TGF-beta responsive promoter-reporter construct (p3TP-Lux). A transiently transfected RII promoter-reporter element (RII-chloramphenicol acetyltransferase) showed an increase in activity in the 5-aza-2'-dC-treated MCF-7L cells compared with untreated cells, suggesting the activation of a transactivator of RII transcription. Using electrophoretic mobility shift assays, the enhanced binding of proteins from 5-aza-2'-dC-treated MCF-7L nuclear extracts to radiolabeled Sp1 oligonucleotides was demonstrated. An RII promoter-chloramphenicol acetyltransferase construct containing a mutation in the Sp1 site was not expressed in the 5-aza-2'-dC-treated MCF-7L cells, further demonstrating that induction of Sp1 activity by 5-aza-2'-dC in the MCF-7L cells was critical to RII expression. Northern analysis indicated that 5-aza-2'-dC treatment did not affect the Sp1 transcript levels. Western blot analysis revealed an increase of Sp1 protein in the 5-aza-2'-dC-treated MCF-7L cells, but there was no change in the c-Jun levels. Studies after cyclohexamide treatment suggested an increase in the Sp1 protein stability from the 5-aza-2'-dC-treated MCF-7L extracts compared with untreated control extracts. These results indicate that the transcriptional repression of RII in the ER+ breast cancer cells is caused by suboptimal activity of Sp1, whereas treatment with 5-aza-2'-dC stabilizes the protein thus increasing steady-state Sp1 levels and thereby leads to enhanced RII transcription and subsequent restoration of TGF-beta sensitivity.

Authors+Show Affiliations

Department of Biochemistry and Molecular Biology, Medical College of Ohio, Toledo, Ohio 43614, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9632722

Citation

Ammanamanchi, S, et al. "Induction of Transforming Growth Factor-beta Receptor Type II Expression in Estrogen Receptor-positive Breast Cancer Cells Through SP1 Activation By 5-aza-2'-deoxycytidine." The Journal of Biological Chemistry, vol. 273, no. 26, 1998, pp. 16527-34.
Ammanamanchi S, Kim SJ, Sun LZ, et al. Induction of transforming growth factor-beta receptor type II expression in estrogen receptor-positive breast cancer cells through SP1 activation by 5-aza-2'-deoxycytidine. J Biol Chem. 1998;273(26):16527-34.
Ammanamanchi, S., Kim, S. J., Sun, L. Z., & Brattain, M. G. (1998). Induction of transforming growth factor-beta receptor type II expression in estrogen receptor-positive breast cancer cells through SP1 activation by 5-aza-2'-deoxycytidine. The Journal of Biological Chemistry, 273(26), 16527-34.
Ammanamanchi S, et al. Induction of Transforming Growth Factor-beta Receptor Type II Expression in Estrogen Receptor-positive Breast Cancer Cells Through SP1 Activation By 5-aza-2'-deoxycytidine. J Biol Chem. 1998 Jun 26;273(26):16527-34. PubMed PMID: 9632722.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Induction of transforming growth factor-beta receptor type II expression in estrogen receptor-positive breast cancer cells through SP1 activation by 5-aza-2'-deoxycytidine. AU - Ammanamanchi,S, AU - Kim,S J, AU - Sun,L Z, AU - Brattain,M G, PY - 1998/6/20/pubmed PY - 1998/6/20/medline PY - 1998/6/20/entrez SP - 16527 EP - 34 JF - The Journal of biological chemistry JO - J Biol Chem VL - 273 IS - 26 N2 - Previous studies suggest that estrogen receptor-positive (ER+) breast cancer cells acquire resistance to transforming growth factor-beta (TGF-beta) because of reduced expression levels of TGF-beta receptor type II (RII). We now report that treatment of ER+ breast cancer cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-2'-dC) leads to accumulation of RII transcript and protein in three different cell lines. RII induction restored TGF-beta response in MCF-7L breast cancer cells as indicated by the enhanced activity of a TGF-beta responsive promoter-reporter construct (p3TP-Lux). A transiently transfected RII promoter-reporter element (RII-chloramphenicol acetyltransferase) showed an increase in activity in the 5-aza-2'-dC-treated MCF-7L cells compared with untreated cells, suggesting the activation of a transactivator of RII transcription. Using electrophoretic mobility shift assays, the enhanced binding of proteins from 5-aza-2'-dC-treated MCF-7L nuclear extracts to radiolabeled Sp1 oligonucleotides was demonstrated. An RII promoter-chloramphenicol acetyltransferase construct containing a mutation in the Sp1 site was not expressed in the 5-aza-2'-dC-treated MCF-7L cells, further demonstrating that induction of Sp1 activity by 5-aza-2'-dC in the MCF-7L cells was critical to RII expression. Northern analysis indicated that 5-aza-2'-dC treatment did not affect the Sp1 transcript levels. Western blot analysis revealed an increase of Sp1 protein in the 5-aza-2'-dC-treated MCF-7L cells, but there was no change in the c-Jun levels. Studies after cyclohexamide treatment suggested an increase in the Sp1 protein stability from the 5-aza-2'-dC-treated MCF-7L extracts compared with untreated control extracts. These results indicate that the transcriptional repression of RII in the ER+ breast cancer cells is caused by suboptimal activity of Sp1, whereas treatment with 5-aza-2'-dC stabilizes the protein thus increasing steady-state Sp1 levels and thereby leads to enhanced RII transcription and subsequent restoration of TGF-beta sensitivity. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/9632722/Induction_of_transforming_growth_factor_beta_receptor_type_II_expression_in_estrogen_receptor_positive_breast_cancer_cells_through_SP1_activation_by_5_aza_2'_deoxycytidine_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(18)80773-6 DB - PRIME DP - Unbound Medicine ER -