MEK activity controls IL-8 expression in tamoxifen-resistant MCF-7 breast cancer cells

  • Authors:
    • Sangmin Kim
    • Myeongjin Jeon
    • Jeong Eon Lee
    • Seok Jin Nam
  • View Affiliations

  • Published online on: January 13, 2016     https://doi.org/10.3892/or.2016.4557
  • Pages: 2398-2404
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Abstract

Although tamoxifen reduces disease progression, tamoxifen resistance occurs during the course of estrogen receptor-positive [ER+] breast cancer treatment. In the present study, we investigated the possibility that interleukin-8 (IL-8) is a prognostic marker for tamoxifen resistance and aimed to clarify the regulation of IL-8 expression in tamoxifen-resistant cells. Clinically, IL-8 expression is positively correlated with survival in luminal A type breast cancer patients, but not in luminal B type breast cancer patients. In addition, the levels of IL-8 mRNA and protein expression were significantly increased in tamoxifen-resistant (TamR) cells compared to tamoxifen-sensitive (TamS) cells. To determine the regulatory mechanism of IL-8 expression in TamR cells, we analyzed the activities of signaling molecules. Our results showed that the phosphorylation levels of MEK and Akt were markedly increased in TamR cells, but there was no change in the phosphorylation level of p38 MAPK. On the contrary, we observed that elevated IL-8 mRNA expression was suppressed by a specific MEK1/2 inhibitor, UO126, but not by the specific PI-3K inhibitor LY294002, in TamR cells, whereas, we found that overexpression of constitutively active-MEK (CA-MEK) significantly increased the levels of IL-8 mRNA expression in TamS cells. Finally, we investigated the effect of the specific CXCR1/2 inhibitor SB225002 on anchorage-independent growth of TamR cells, and found that the growth was completely suppressed by SB225002. Taken together, our results demonstrate that IL-8 expression is regulated through a MEK/ERK-dependent pathway in TamR cells, suggesting that IL-8 and its receptors may be promising therapeutic targets for overcoming tamoxifen resistance.
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April-2016
Volume 35 Issue 4

Print ISSN: 1021-335X
Online ISSN:1791-2431

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Spandidos Publications style
Kim S, Jeon M, Lee JE and Nam SJ: MEK activity controls IL-8 expression in tamoxifen-resistant MCF-7 breast cancer cells. Oncol Rep 35: 2398-2404, 2016.
APA
Kim, S., Jeon, M., Lee, J.E., & Nam, S.J. (2016). MEK activity controls IL-8 expression in tamoxifen-resistant MCF-7 breast cancer cells. Oncology Reports, 35, 2398-2404. https://doi.org/10.3892/or.2016.4557
MLA
Kim, S., Jeon, M., Lee, J. E., Nam, S. J."MEK activity controls IL-8 expression in tamoxifen-resistant MCF-7 breast cancer cells". Oncology Reports 35.4 (2016): 2398-2404.
Chicago
Kim, S., Jeon, M., Lee, J. E., Nam, S. J."MEK activity controls IL-8 expression in tamoxifen-resistant MCF-7 breast cancer cells". Oncology Reports 35, no. 4 (2016): 2398-2404. https://doi.org/10.3892/or.2016.4557