Evaluating Expression of the STAG1 Gene as a Potential Breast Cancer Biomarker

Main Article Content

Inam J Lafta
Bassam K Kudhair
Oluyinka A Iyiola
Emad A Ahmed
Tachung Chou


STAG proteins, which are part of the cohesin complex and encoded by the STAG genes, are known as Irr1/Scc3 in yeast and as SA/STAG/stromalin in mammals. There are more variants as there are alternate splice sites, maybe three open reading frames (ORFs) code for three main proteins, including: SA1 (STAG1), SA2 (STAG2) and SA3 (STAG3). The cohesin protein complex has various essential roles in eukaryotic cell biology. This study compared the expression of the STAG1 gene in four different breast cancer cell lines, including: MCF-7, T-47D, MDA-MB-468, and MDA-MB-231 and normal breast tissue. RNA was extracted from these cell lines and mRNA was converted to cDNA, and then expression of the STAG1 gene was quantified by three sets of specific primer pairs using Real Time-quantitative PCR (RT-qPCR). The findings show significantly different over-expression of STAG1 in these cancer cell lines in comparison with the normal tissue, and the cell lines were different in their expression levels. In conclusion, the STAG1 gene can be postulated as a candidate breast cancer biomarker that needs to be further evaluated in breast tumor biopsies.


Download data is not yet available.

Article Details

How to Cite
Lafta, I. J., Kudhair, B. K. ., Iyiola, O. A. ., Ahmed, E. A. ., & Chou, T. . (2021). Evaluating Expression of the STAG1 Gene as a Potential Breast Cancer Biomarker. The Iraqi Journal of Veterinary Medicine, 45(2), 7–13. https://doi.org/10.30539/ijvm.v45i2.1255


Alabbody HH, Lafta IJ. Incidence of canine digestive system tumours in Baghdad Province. Iraqi J. Vet. Med. 2019; 43(2): 67-76. DOI: https://doi.org/10.30539/iraqijvm.v43i2.533

Mishra A, Verma M. Cancer biomarkers: are we ready for the prime time? Cancers. 2010; 2:190-08. DOI: https://doi.org/10.3390/cancers2010190

Guacci V, Koshland D, Strunnikov A. A direct link between sister chromatid cohesion and chromosome condensation revealed through the analysis of MCD1 in S. cerevisiae. Cell. 1997; 91:47-57. DOI: https://doi.org/10.1016/S0092-8674(01)80008-8

Canudas S, Smith S. Differential regulation of telomere and centromere cohesion by the Scc3 homologues SA1 and SA2, respectively, in human cells. J Cell Biol. 2009; 187:165-73. DOI: https://doi.org/10.1083/jcb.200903096

Ghiselli G, Iozzo RV. Overexpression of bamacan/SMC3 causes transformation. J Biol Chem. 2000; 275:20235-8. DOI: https://doi.org/10.1074/jbc.C000213200

Peters JM, Tedeschi A, Schmitz J. The cohesin complex and its roles in chromosome biology. Genes Dev. 2008; 22: 3089-114. DOI: https://doi.org/10.1101/gad.1724308

Sumara I, Vorlaufer E, Gieffers C, Peters BH, Peters JM. Characterization of vertebrate cohesin complexes and their regulation in prophase. J Cell Biol. 2000; 151: 749-62. DOI: https://doi.org/10.1083/jcb.151.4.749

Vass S, Cotterill S, Valdeolmillos AM, Barbero JL, Lin E, Warren WD, Heck MM. 2003. Depletion of Drad21/Scc1 in Drosophila cells leads to instability of the cohesin complex and disruption of mitotic progression. Curr Biol. 2003; 13: 208-18. DOI: https://doi.org/10.1016/S0960-9822(03)00047-2

Mc Intyre J, Muller EG, Weitzer S, Snydsman BE, Davis TN, Uhlmann F. In vivo analysis of cohesin architecture using FRET in the budding yeast Saccharomyces cerevisiae. EMBO J. 2007; 26: 3783-93. DOI: https://doi.org/10.1038/sj.emboj.7601793

Wartin E, Peters JM. The cohesin complex is required for the DNA damage-induced G2/M checkpoint in mammalian cells. EMBO J. 2009; 28: 2625-35. DOI: https://doi.org/10.1038/emboj.2009.202

Hakimi MA, Bochar DA, Schmiesing JA, Dong Y, Barak OG, Speicher DW, Yokomori K, Shiekhattar R. A chromatin remodelling complex that loads cohesin onto human chromosomes. Nature. 2002; 418: 994-8. DOI: https://doi.org/10.1038/nature01024

Rollins RA, Morcillo P, Dorsett D. Nipped-B, a Drosophila homologue of chromosomal adherins, participates in activation by remote enhancers in the cut and Ultrabithorax genes. Genetics. 1999; 152: 577-93. DOI: https://doi.org/10.1093/genetics/152.2.577

Rhodes JM, Bentley FK, Print CG, Dorsett D, Misulovin Z, Dickinson EJ, Crosier KE, Crosier PS, Horsfield JA. Positive regulation of c-Myc by cohesin is direct, and evolutionarily conserved. Dev Biol. 2010; 344: 637-49. DOI: https://doi.org/10.1016/j.ydbio.2010.05.493

Schmidt D, Schwalie PC, Ross-Innes CS, Hurtado A, Brown GD, Carroll JS, Flicek P, Odom DT. A CTCF-independent role for cohesin in tissue-specific transcription. Genome Res. 2010; 20: 578-88. DOI: https://doi.org/10.1101/gr.100479.109

Schaaf CA, Misulovin Z, Sahota G, Siddiqui AM, Schwartz YB, Kahn TG, Pirrotta V, Gause M, Dorsett D. Regulation of the Drosophila Enhancer of split and invected-engrailed gene complexes by sister chromatid cohesion proteins. PLoS One. 2009; 4: e6202. DOI: https://doi.org/10.1371/journal.pone.0006202

Xu H, Tomaszewski JM, Mckay MJ. Can corruption of chromosome cohesion create a conduit to cancer? Nat Rev Cancer. 2011; 11:199-210. DOI: https://doi.org/10.1038/nrc3018

Rhodes JM, Mcewan M, Horsfield JA. Gene regulation by cohesin in cancer: is the ring an unexpected party to proliferation? Mol Cancer Res. 2011; 9: 1587-607. DOI: https://doi.org/10.1158/1541-7786.MCR-11-0382

Alabbody HH, Lafta IJ. Clinical pathology and immuno-histochemistry of mammary tumors from military and pet dogs in Iraq. Online J Vet Res. 2018; 22(7): 547-560.

Lafta IJ, Kudhair BK, Alabid NN. Characterization of the major human STAG3 variants using some proteomics and bioinformatics assays. Egyp J Med Hum Genet; 2020; 21:9. DOI: https://doi.org/10.1186/s43042-020-0051-0

Lafta IJ. STAG3 gene expression in breast cancer cells [dissertation]. University of Sheffield, Sheffield, UK; 2016.

Pfaffl MW. A new mathematical model for relative quantification in real-time RT-PCR. Nucleic Acids Res. 2001; 29: e45. DOI: https://doi.org/10.1093/nar/29.9.e45

Livak KJ, Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. Methods. 2001; 25: 402-8. DOI: https://doi.org/10.1006/meth.2001.1262

Subramaniam DS, Isaacs C. Utilizing prognostic and predictive factors in breast cancer. Curr Treat Options Oncol. 2005; 6:147-59. DOI: https://doi.org/10.1007/s11864-005-0022-1

Bieche I, Vacher S, Lallemand F, Tozlu-Kara S, Bennani H, Beuzelin M, Driouch K, Rouleau E, Lerebours F, Ripoche H, Cizeron-Clairac G, Spyratos F, Lidereau R. Expression analysis of mitotic spindlecheckpoint genes in breast carcinoma: role of NDC80/HEC1 in early breast tumorigenicity, and a two-gene signature for aneuploidy. Mol Cancer. 2011; 10, 23. DOI: https://doi.org/10.1186/1476-4598-10-23

Croucher A. Investigating the expression and function of meiotic genes in human tumours [dissertation]. University of Sheffield, Sheffield, UK; 2012.

Kao J, Salari K, Bocanegra M, Choi YL, Girard L, Gandhi J, Kwei KA, Hernandez-Boussard T, Wang P, Gazdar AF, Minna JD, Pollack JR. Molecular profiling of breast cancer cell lines defines relevant tumor models and provides a resource for cancer gene discovery. PLoS One. 2009; 4: e6146 DOI: https://doi.org/10.1371/journal.pone.0006146

Most read articles by the same author(s)