Silencing the OCT4-PG1 pseudogene reduces OCT-4 protein levels and changes characteristics of the multidrug resistance phenotype in chronic myeloid leukemia
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Cancer stem cells show epigenetic plasticity and intrinsic resistance to anti-cancer therapy, rendering capable of initiating cancer relapse and progression. Transcription factor OCT-4 regulates various pathways in stem cells, but its expression can be regulated by pseudogenes. This work evaluated how OCT4-PG1 pseudogene can affect OCT-4 expression and mechanisms related to the multidrug resistance (MDR) phenotype in FEPS cells. Considering that OCT-4 protein is a transcription factor that regulates expression of ABC transporters, level of gene expression, activity of ABC proteins and cell sensitivity to chemotherapy were evaluated after OCT4-PG1 silencing. Besides we set up a STRING network. Results showed that after OCT4-PG1 silencing, cells expressed OCT-4 gene and protein to a lesser extent than mock cells. The gene and protein expression of ABCB1, as well as its activity were reduced. On the other hand, ALOX5 and ABCC1 genes was increased even as the activity of this transporter. Moreover, the silencing cells become sensitive to two chemotherapics tested. The network structure demonstrated that OCT4-PG1 protein interacts directly with OCT-4, SOX2, and NANOG and indirectly with ABC transporters. We conclude that OCT4-PG1 pseudogene plays a key role in the regulation OCT-4 transcription factor, which alters MDR phenotype in the FEPS cell line.
KeywordsABC transporters Cancer stem cells MRP1 protein P-glycoprotein STRING database
Carboxy fluorescein diacetate
Cancer stem cells
Human embryonic stem cells
Multidrug resistance associated protein
- Rho 123
The authors thank Dr. Vivian Rumjanek (Tumoral Immunology Laboratory at the Medical Biochemistry Institute of the Federal University of Rio de Janeiro, Brazil) for providing and allowing the use of the FEPS cell line.
This work was supported by the National Program for Academic Cooperation (PROCAD/CAPES) [Grant Numbers 2951/2014], Brazil. Lettnin, A.P. received a graduate fellowship from CAPES. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- 27.Fatemian T, Othman I, Chowdhury EH (2014) Strategies and validation for siRNA-based therapeutics for the reversal of multi-drug resistance in cancer. Drug Discov 19:71–78Google Scholar
- 34.Wang L, Guo Z-Y, Zhang R, Xin B, Chen R, Zhao J, Wang T, Wen W-H, Jia L-T, Yao L-B, Yang A-G (2013) Pseudogene OCT4-pg4 functions as a natural micro RNA sponge to regulate OCT4 expression by competing for miR-145 in hepatocellular carcinoma. Carcinogenesis 34(8):1773–1781. https://doi.org/10.1093/carcin/bgt139 CrossRefGoogle Scholar
- 45.Tang Y-A, Chen C-H, Sun SH, Cheng C-P, Tseng VS, Hsu H-S, Su W-C, Lai W-W, Wang Y-C (2015) Global Oct4 target gene analysis reveals novel downstream PTEN and TNC genes required for drug-resistance and metastasis in lung cancer. Nucleic Acids Res 43(3):1593–1608. https://doi.org/10.1093/nar/gkv024 CrossRefGoogle Scholar
- 46.Kobayashi I, Takahashi F, Nurwidya F, Nara T, Hashimoto M, Murakami A, Yagishita S, Tajima K, Hidayat M, Shimada N, Suina K, Yoshioka Y, Sasaki S, Moriyama M, Moriyama H, Takahashi K (2016) Oct4 plays a crucial role in the maintenance of gefitinib-resistant lung cancer stem cells. Biochem Biophys Res Commun 473:125–132CrossRefGoogle Scholar
- 54.Loe DW, Deeley RG, Cole SP (1998) Characterization of vincristine transport by the M(r) 190,000 multidrug resistance protein (MRP): evidence for cotransport with reduced glutathione. Cancer Res 58:5130–5136Google Scholar
- 63.Moreira MAM, Bagni C, de Pinho MB, Mac-Cormick TM, dos Santos Mota M, Pinto-Silva FE, Daflon-Yunes N, Rumjanek VM (2014) Changes in gene expression profile in two multidrug resistant cell lines derived from a same drug sensitive cell line. Leuk Res 38(8):983–987. https://doi.org/10.1016/j.leukres.2014.06.001 CrossRefGoogle Scholar