Nevertheless, after optimal surgical debulking of the tumor and standard chemotherapy, patients with advanced disease experience 5-year survival rate [4]. Despite the relative sensitivity of ovarian cancer to chemotherapy, clinical chemotherapeutic treatment often encounters drug resistance [5]. Development of this acquired resistance represents the major limitation to successful treatment. Consequently, there is a pressing need to identify see more the mechanisms underlying resistance in order to develop novel drugs to re-sensitize tumor cells to primary chemotherapy. Recently, histologic subtype has been recognized as one of the key factors related to chemosensitivity in ovarian cancer. Especially,

clear cell carcinoma of the ovary, which is recognized as a distinct histologic entity in the World Health Organization classification of ovarian tumors, demonstrates a distinctly different clinical behavior from other epithelial ovarian cancers. Several studies showed that patients with clear cell carcinoma had a poor prognosis, partly due to a low response rate to chemotherapy [3–5]. However, little is known about the mechanisms of chemoresistance (intrinsic resistance) of clear cell carcinoma [6]. Response to

taxane/platinum in clear cell carcinoma is still controversial. Reed et al. this website [7] suggests that common resistance mechanism might be a central determinant for response to current combination therapy

regardless of histologic type. The cytoprotective chaperone protein, clusterin (CLU), has been reported to be involved in numerous physiological processes important for carcinogenesis and tumor growth, including apoptotic cell death, cell cycle regulation, DNA repair, cell adhesion, tissue remodeling, lipid transportation, membrane recycling, and immune system regulation [8]. CLU protein is commonly up-regulated by chemotherapy and radiotherapy in cancer cells, and contributes to cancer cell resistance in vitro and in various animal models of cancer by blocking apoptosis [9]. Cytoplasmic CLU is consistently reported to be associated with chemoresistance Temsirolimus concentration and it is present in a wide range of advanced cancers as shown in human tumor tissues from prostate [10, 11], renal [12], breast [13], ovarian [14], colon [15], lung [16], pancreas [17], cervix [18], melanoma [19], glioma [20], and anaplastic large cell lymphoma [21]. Recent clinical trials using OGX-011, an antisense oligodeoxynucleotide specifically targeting CLU by complementing CLU mRNA translation initiation site have been launched [22]. OGX-011 potently inhibits CLU expression and enhances the efficacy of anticancer therapies in vitro and in vivo [23, 16]. In addition to a phosphorothioate backbone, OGX-011 incorporates a 2′-methoxyethyl modification to the ribose moiety on the flanking four nucleotides.