Expression of HER2 and estrogen receptor α depends upon nuclear localization of Y-box binding protein-1 in human breast cancers

Teruhiko Fujii, Akihiko Kawahara, Yuji Basaki, Satoshi Hattori, Kazutaka Nakashima, Kenji Nakano, Kazuo Shirouzu, Kimitoshi Kohno, Takashi Yanagawa, Hideaki Yamana, Kazuto Nishio, Mayumi Ono, Michihiko Kuwano, Masayoshi Kage

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71 Citations (Scopus)


In our present study, we examined whether nuclear localization of Y-box binding protein-1 (YB-1) is associated with the expression of epidermal growth factor receptors (EGFR), hormone receptors, and other molecules affecting breast cancer prognosis. The expression of nuclear YB-1, clinicopathologic findings, and molecular markers [EGFR, HER2, estrogen receptor (ER)α, ERβ, progesterone receptor, chemokine (C-X-C motif) receptor 4 (CXCR4), phosphorylated Akt, and major vault protein/lung resistance protein] were immunohistochemically analyzed. The association of the expression of nuclear YB-1 and the molecular markers was examined in breast cancer cell lines using microarrays, quantitative real-time PCR, and Western blot analyses. Knockdown of YB-1 with siRNA significantly reduced EGFR, HER2, and ERA expression in ERα-positive, but not ERα-negative, breast cancer cell lines. Nuclear YB-1 expression was positively correlated with HER2 (P = 0.0153) and negatively correlated with ERα (P = 0.0122) and CXCR4 (P = 0.0166) in human breast cancer clinical specimens but was not correlated with EGFR expression. Nuclear YB-1 expression was an independent prognostic factor for overall (P = 0.0139) and progression-free (P = 0.0280) survival. In conclusion, nuclear YB-1 expression might be essential for the acquisition of malignant characteristics via HER2-Akt-dependent pathways in breast cancer patients. The nuclear localization of YB-1 could be an important therapeutic target against not only multidrug resistance but also tumor growth dependent on HER2 and ERα.

Original languageEnglish
Pages (from-to)1504-1512
Number of pages9
JournalCancer Research
Issue number5
Publication statusPublished - Mar 1 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


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