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Low expression of the X-linked ribosomal protein S4 in human serous epithelial ovarian cancer is associated with a poor prognosis

Serges P Tsofack1, Liliane Meunier23, Lilia Sanchez3, Jason Madore23, Diane Provencher23, Anne-Marie Mes-Masson23 and Michel Lebel14*

Author Affiliations

1 Centre de Recherche en Cancérologie de l’Université Laval, Hôpital Hôtel-Dieu de Québec, Quebec City, QC, Canada

2 Institut du cancer de Montréal, Montréal, QC, Canada

3 Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montreal, QC, Canada

4 Centre de Recherche en Cancérologie de l’Université Laval, Hôpital Hôtel-Dieu de Québec, 9 McMahon Sreet, Quebec City, QC G1R 2J6, Canada

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BMC Cancer 2013, 13:303  doi:10.1186/1471-2407-13-303

Published: 22 June 2013



The X-linked ribosomal protein S4 (RPS4X), which is involved in cellular translation and proliferation, has previously been identified as a partner of the overexpressed multifunctional protein YB-1 in several breast cancer cells. Depletion of RPS4X results in consistent resistance to cisplatin in such cell lines.


As platinum-based chemotherapy is a standard first line therapy used to treat patients with ovarian cancer, we evaluated the prognostic value of RPS4X and YB-1 at the protein level in specimen from 192 high-grade serous epithelial ovarian cancer patients.


Immunohistochemistry studies indicated that high expression of RPS4X was associated with a lower risk of death and later disease progression (HR = 0.713, P = 0.001 and HR = 0.761, P = 0.001, respectively) as compared to low expression of RPS4X. In contrast, YB-1 was not significantly associated with either recurrence or survival time in this cohort. Finally, the depletion of RPS4X with different siRNAs in two different ovarian cancer cell lines reduced their proliferative growth rate but more importantly increased their resistance to cisplatin.


Altogether, these results suggest that the levels of RPS4X could be a good indicator for resistance to platinum-based therapy and a prognostic marker for ovarian cancer. Our study also showed that RPS4X is an independent prognostic factor in patients with serous epithelial ovarian cancer.

Serous epithelial ovarian cancer; YB-1; RPS4X; Cisplatin