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Received date : 22-1-2023 Revised date : 18-02-2023 Accepted date : 22-02-2023 Published date : 31-03-2023

Mediterr J Pharm Pharm Sci 3 (1): 25-33, 2023

DOI: https://doi.org/10.5281/zenodo.7771344

Original Research

Modulation of TCDD induced Cyp1a1 mRNA by the Co-repressor SMRT

Issa E.A. Amara and Shaban E.A. Saad


Environmental factors are known to influence carcinogenesis. Pollutants, such as heterocyclic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs) are examples of environmental borne procarcinogens. Procarcinogens are not active carcinogens although, they require bio-activation, via enzymes such as cytochrome P450 (CYP) to transform to active product. CYP1A1 isoform, regulated by aryl hydrocarbon receptor (AhR) plays a significant role in the bio-activation of PAHs and HAs. AhR has multiple co-activators and co-repressors for AhR that have been identified S remarkably. Silencing mediator for retinoid and thyroid hormone receptors (SMRT) was designated as a major co-repressor for AhR. In the present study, it is examined the effect of SMRT over expression on the cyp1a1 mRNA levels in murine hepatoma Hepa 1c1c7 cell line. Hepa 1c1c7 cells were maintained in Dulbecco’s Modified Eagle Medium (DMEM) and competent cells have successfully been produced using calcium chloride method. Cells were transformed using plasmid DNA and Lipofectamine. TCDD (2, 3, 7, 8-tetrachlorodibenzo-p-dioxin) was employed as an inducing agent for CYP1A1. The total cellular RNA was isolated and real-time PCR of Cyp1a1 was conducted. A statistical analysis was conducted by using one-way analysis of variance followed by Student-Newman-Keuls test. The results showed that cells transfected with the co-repressor SMRT has lower TCDD-mediated induction of cyp1a1 mRNA without affecting constitutive Cyp1a1 mRNA levels, i.e., SMRT was able to significantly decrease inducible Cyp1a1 mRNA levels in Hepa 1c1c7 cells. The present findings also demonstrated that calcium chloride is a convenient method for routine transformation. Thus, this study opens a new avenue for the management of carcinogenesis involving CYP1A1 inducing carcinogens.


1. Tavan E, Cayuela C, Antoine J-M, Trugnan G, Chaugier C, Cassand P (2002) Effects of dairy products on heterocyclic aromatic amine-induced rat colon carcinogenesis. Carcinogenesis. 23 (3): 477-483. doi.org/10.1093/carcin/23.3.477

2. Gonzalez FJ, Fernandez-Salguero P (1998) The aryl hydrocarbon receptor: studies using the AHR-null mice. Drug Metabolism and Disposition. 26 (12): 1194-1198. PMID: 9860927.

Nelson DR, Koymans L, Kamataki T, Stegeman JJ, Feyereisen R, Waxman DJ, Waterman MR, Gotoh O, Coon MJ, Estabrook RW, Gunsalus IC, Nebert DW (1996) P450 superfamily: update on new sequences, gene mapping, accession numbers and nomenclature. Pharmacogenetics. 6 (1): 1-42. doi: 10.1097/00008571-199602000-00002.

3. Fontana RJ, Lown KS, Paine MF, Fortlage L, Santella RM, Felton JS, Knize MG, Greenberg A, Watkins PB (1999) Effects of a chargrilled meat diet on expression of CYP3A, CYP1A, and P-glycoprotein levels in healthy volunteers. Gastroenterology. 117 (1):  89-98. doi: 10.1016/s0016-5085(99)70554-8.

Chen YY, Chan KM (2016) Differential effects of metal ions on TCDD-induced cytotoxicity and cytochrome P4501A1 gene expression in a zebrafish liver (ZFL) cell-line. Metallomics. 8: 236-251. doi.org/10.1039/C5MT00219B.

5.  Hines RN, Mathis JM, Jacob CS (1988) Identification of multiple regulatory elements on the human cytochrome P450IA1 gene. Carcinogenesis. 9 (9): 1599-1605. doi: 10.1093/carcin/9.9.1599.

6.  Carlson DB, Perdew GH (2002) A dynamic role for the Ah receptor in cell signaling? Insights from a diverse group of Ah receptor interacting proteins. Journal of Biochemical and Molecular Toxicology. 16 (6): 317-325. doi: 10.1002/jbt.10051.

Chen YY, Chan KM (2018) Modulations of TCDD-mediated induction of zebra-fish cyp1a1 and the AHR pathway by administering Cd2+in vivo. Chemosphere.210: 577-587. doi: 10.1016/j.chemosphere.2018.07.032.

8.  Gibson GG, Skett P (2001) Introduction to drug metabolism. 3rd Ed., Cheltenham Nelson Thornes 256, Springer Pub. (USA). ISBN: 10: 0412263904I. SBN: 13: 9780412263903.

9.  Denison MS, Nagy SR (2003) Activation of the aryl hydrocarbon receptor by structurally diverse exogenous and endogenous chemicals, in Annual Review of Pharmacology and Toxicology. 34: 309-334. doi: 10.1146/annurev.pharmtox.43.100901.135828. 

10.  Vecchini F, Lenoir-Viale MC, Cathelineaue C, Magdalour J, Bernard BA, Shroot B (1994) Presence of a retinoid responsive element in the promoter region of the human cytochrome P4501A1 gene. Biochem Biophys Res Commun.  201 (3): 1205-1212. doi: 10.1006/bbrc.1994.1833.

11.  Delescluse C, Lemaire G, de Sousa G, Rahmani R (2000) Is CYP1A1 induction always related to AHR signaling pathway? Toxicology. 153 (1-3): 73-82. doi: 10.1016/s0300-483x(00)00305-x.

12.  Misiti S, Schomburg L, Yen PM, Chin WW (1998) Expression and hormonal regulation of coactivator and corepressor genes. Endocrinology. 139 (5): 2493-500. doi: 10.1210/endo.139.5.5971.

13.  Nguyen TA, Hoivik D, Lee JE, Safe S (1999) Interactions of nuclear receptor coactivator/corepressor proteins with the aryl hydrocarbon receptor complex. Archives of Biochemistry and Biophysics. 367 (2): 250-257. doi: 10.1006/abbi.1999.1282.

14.  Park EJ, Schroen DJ, Yang M, Li H, LL, Chen JD (1999) SMRTe, a silencing mediator for retinoid and thyroid hormone receptors-extended isoform that is more related to the nuclear receptor corepressor. Proceedings of the National Academy of Sciences of the United states of America. 96 (7): 3519-3524.

15.  Jepsen K, Rosenfeld MG (2002) Biological roles and mechanistic actions of co-repressor complexes. Journal of Cell Science. 115 (Pt 4): 689-698. doi: 10.1242/jcs.115.4.689.

16.  Kransler KM, McGarrigle BP, Olson JR (2007) Comparative developmental toxicity of 2,3,7,8-tetrachloro-dibenzo-p-dioxin in the hamster, rat and guinea pig. Toxicology. 229 (3): 214-225. doi: 10.1016/j.tox.2006.10.019. 

17.  McKenna NJ, O'Malley BW (2002) Minireview: nuclear receptor coactivators--an update. Endocrinology. 143 (7): 2461-2465. doi: 10.1210/endo.143.7.8892.

18.  Naar AM, Lemon BD, Tjian R (2001) Transcriptional coactivator complexes. Annual Review of Biochemistry. 70: 475-501. doi: 10.1146/annurev.biochem.70.1.475.

19.  Xu, W (2005) Nuclear receptor coactivators: the key to unlock chromatin. Biochemistry and Cell Biology. 83 (4): 418-428. doi: 10.1139/o05-057.

20.  Lazar MA (2003) Nuclear receptor corepressors. Nuclear Receptor Signaling. 1: e001.  doi: 10.1621/nrs.01001.

21.  Goodson M, Jonas BA, Privalsky MA (2005) Corepressors: custom tailoring and alterations while you wait. Nuclear Receptor Signal. 3: e003. doi: 10.1621/nrs.03003.

22.  Chen JD, Evans RM (1995) A transcriptional co-repressor that interacts with nuclear hormone receptors. Nature. 377 (6548): 454-457. doi: 10.1038/377454a0.

23.  Horlein AJ, Naar AM, Heinzel T, Torchia J, Gloss B, Kurokawa R, Ryan A, Kamei Y, Soderstrom M, Glass CK (1995) Ligand-independent repression by the thyroid hormone receptor mediated by a nuclear receptor co-repressor. Nature. 377 (6548): 397-404. doi: 10.1038/377397a0.

24.  Ordentlich P, Dowons M, Xie W, Genin A, Spinner NB, Evans RM (1999) Unique forms of human and mouse nuclear receptor corepressor SMRT. Proceedings of the National Academy of Sciences of the United States of America. 96 (6): 2639-4264. doi: 10.1073/pnas.96.6.2639.

25.  Glass CK, Rosenfeld MG (2000) The coregulator exchange in transcriptional functions of nuclear receptors. Genes and Developments. 14 (2): 121-141. PMID: 10652267.

26.  Aranda A, Pascual A (2001) Nuclear hormone receptors and gene expression. Physiological Reviews. 81 (3): 1269-1304.  doi: 10.1152/physrev.2001.81.3.1269.

27.    Zeng L, Zhou MM (2002) Bromodomain: an acetyl-lysine binding domain. FEBS Letters. 513 (1): 124-128. doi: 10.1016/s0014-5793(01)03309-9.

28.  Karagianni P, Wong J (2007) HDAC3: taking the SMRT-N-CoRrect road to repression. Oncogene. 26 (37): 5439-5449. doi: 10.1038/sj.onc.1210612.

29.  Patriziand B, de Cumis MS (2018) TCDD toxicity mediated by epigenetic mechanisms. International Journal of Molecular Sciences. 19 (12): 2-15. 4101. doi.org/10.3390/ijms19124101.

Citation :

Amara & Saad (2023) Modulation of TCDD induced Cyp1a1 mRNA by the Co-repressor SMRT. Mediterr J Pharm Pharm Sci. 3 (1): 25 - 33. https://doi.org/10.5281/zenodo.7771344

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