TGFBI promoter hypermethylation correlating with paclitaxel chemoresistance in ovarian cancer

Epithelial ovarian cancer is the most lethal gynecologic malignancy, with 21 990 estimated new cases and 15 460 deaths in the USA in 2011 [1]. Reasons for this high lethality include the advanced stage at which patients are diagnosed and the inherent aggressive biology of this cancer.Maximal surgical cytoreduction followed by systemic chemotherapy with carboplatin and paclitaxel is the current standard treatment modality for advanced ovarian cancer [2]. A key feature of ovarian cancer is its sensitivity to chemotherapeutic drugs such as paclitaxel, a prototype taxane, stabilizes microtubule polymers leading to mitotic arrest and apoptosis [3]. Unfortunately, ovarian cancer cells, with their unstable genomes [4], are initially sensitive to these drugs, but long term utilization may result in the chemoresistance [5].Epigenetic alterations play an important role in the initiation and progression of cancer [6-8]. Hypermethylation of CpG rich islands in promoter regions of genes has been characterized as a common epigenetic alteration for the silencing or inactivation of tumor suppressor genes and transcriptional repression in human malignancies [9,10], including ovarian cancer [11-13]. In recent years, emerging evidence has also linked epigenetic changes to the development of drug resistance [14,15].Transforming growth factor-beta-inducible gene-h3 (TGFBI) is a secreted protein first identified in a human lung adenocarcinoma cell line treated with transforming growth factor-β [16]. It has been shown to possess tumor suppressor function in vitro studies [17,18], and to be correlated with specific sensitization to paclitaxel by inducing stabilization of microtubules via integrin-mediated signaling pathways [19]. Recently, promoter hypermethylation of TGFBI was found in lung [20,21] and prostate cancer [20]. However, the role of TGFBI methylation in paclitaxel chemoresistance in ovarian cancer is unknown. Therefore, a better understanding of this epigenetic mechanism of TG