Chemotherapy is the standard firstline treatment for advanced stage epithelial ovarian carcinoma (EOC). The tumors are considered “platinum sensitive” if the clinical progression-free interval is more than 6 months, but approximately 20 to 30 of patients progress or their tumors rapidly become resistant to this treatment [1]. These patients with intrinsic chemoresistance who experience a recurrence within 6 months gain little benefit from standard treatment. There is also evidence suggesting that the longer the interval until recurrence, the better the response rate to subsequent chemotherapy [2]. Therefore, chemoresistance for ovarian cancers may be present 12926553 atthe MedChemExpress Licochalcone-A outset of treatment (intrinsic resistance) or may develop during treatment (acquired resistance). Currently, chemoresistance of EOC can only be determined retrospectively after patients have experienced the burden and toxicity of ineffective therapy. Therefore, identification of characteristic molecular biomarkers related to intrinsic chemoresistance in EOC may lead to individually customized therapeutics and improvement of outcomes since standard chemotherapy affords them very little benefit. Several recent studies have used gene microarrays to identify distinct gene expression in intrinsic chemoresistant ovarian cancer patients on different platforms, such as nylon cDNA arrays, Affymetrix chips and Agilent oligonucleotide microarrays [3,4].Biomarkers for Chemoresistant Ovarian CancerThese studies have identified different prognostic and predictor genes which can distinguish early from late relapse or disease progression. However, transcription of a target gene in the tumor may not be a good predictor of drug resistance and prognosis for ovarian cancer. For example, mRNA abundance may not correlate with the corresponding protein expression and function. 58-49-1 Furthermore, for some primary or recurrent ovarian cancer patients, tissue samples are not always available for gene profiling. Unlike with other pelvic/abdominal malignant metastasis, massive ascites are a distinctive clinical manifestation in advanced EOC, with more than 80 of these patients having widespread metastasis to the serosal surfaces and associated peritoneal and/or pleural effusions [5]. Body fluids have been shown to be excellent media for biomarker discovery in cancer, and ascites fluid contains malignant epithelial cells and activated mesothelial cells, which can produce cytokines, growth factors and invasion-promoting components associated with invasion and metastasis [6]. This fluid therefore contains the secretome of ovarian cancer cells and reflects other microenvironmental factors of the malignancy. Thus, applying the ever advancing technique of proteomics to the analysis of ascites may 15755315 facilitate discovery of novel biomarkers that are more sensitive and specific than those currently available. The aim of our study was to screen and identify distinctive biomarkers in ascites of ovarian cancer associated with intrinsic chemoresistance by two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE) technology, which would help identify these patients with 
poor prognosis and improve their clinical outcome with alternative therapies.three times in ice-cold Tris-buffered sucrose solution (10 mM Tris, 250 mM sucrose, pH 7.0) and then scraped and lysed in ice-cold lysis buffer (30 mM Tris-HCl, 7 M urea, 2 M thiourea, 4 w/v CHAPS, pH 8.5). Ascites samples were processed using the ProteoPrep Blue.Chemotherapy is the standard firstline treatment for advanced stage epithelial ovarian carcinoma (EOC). The tumors are considered “platinum sensitive” if the clinical progression-free interval is more than 6 months, but approximately 20 to 30 of patients progress or their tumors rapidly become resistant to this treatment [1]. These patients with intrinsic chemoresistance who experience a recurrence within 6 months gain little benefit from standard treatment. There is also evidence suggesting that the longer the interval until recurrence, the better the response rate to subsequent chemotherapy [2]. Therefore, chemoresistance for ovarian cancers may be present 12926553 atthe outset of treatment (intrinsic resistance) or may develop during treatment (acquired resistance). Currently, chemoresistance of EOC can only be determined retrospectively after patients have experienced the burden and toxicity of ineffective therapy. Therefore, identification of characteristic molecular biomarkers related to intrinsic chemoresistance in EOC may lead to individually customized therapeutics and improvement of outcomes since standard chemotherapy affords 
them very little benefit. Several recent studies have used gene microarrays to identify distinct gene expression in intrinsic chemoresistant ovarian cancer patients on different platforms, such as nylon cDNA arrays, Affymetrix chips and Agilent oligonucleotide microarrays [3,4].Biomarkers for Chemoresistant Ovarian CancerThese studies have identified different prognostic and predictor genes which can distinguish early from late relapse or disease progression. However, transcription of a target gene in the tumor may not be a good predictor of drug resistance and prognosis for ovarian cancer. For example, mRNA abundance may not correlate with the corresponding protein expression and function. Furthermore, for some primary or recurrent ovarian cancer patients, tissue samples are not always available for gene profiling. Unlike with other pelvic/abdominal malignant metastasis, massive ascites are a distinctive clinical manifestation in advanced EOC, with more than 80 of these patients having widespread metastasis to the serosal surfaces and associated peritoneal and/or pleural effusions [5]. Body fluids have been shown to be excellent media for biomarker discovery in cancer, and ascites fluid contains malignant epithelial cells and activated mesothelial cells, which can produce cytokines, growth factors and invasion-promoting components associated with invasion and metastasis [6]. This fluid therefore contains the secretome of ovarian cancer cells and reflects other microenvironmental factors of the malignancy. Thus, applying the ever advancing technique of proteomics to the analysis of ascites may 15755315 facilitate discovery of novel biomarkers that are more sensitive and specific than those currently available. The aim of our study was to screen and identify distinctive biomarkers in ascites of ovarian cancer associated with intrinsic chemoresistance by two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE) technology, which would help identify these patients with poor prognosis and improve their clinical outcome with alternative therapies.three times in ice-cold Tris-buffered sucrose solution (10 mM Tris, 250 mM sucrose, pH 7.0) and then scraped and lysed in ice-cold lysis buffer (30 mM Tris-HCl, 7 M urea, 2 M thiourea, 4 w/v CHAPS, pH 8.5). Ascites samples were processed using the ProteoPrep Blue.
