Abstract. TBX15 is a gene involved in the development of mesodermal derivatives. As the ovaries and the female reproductive system are of mesodermal origin, the aim of the present study was to determine the methylation status of the TBX15 gene promoter and the expression levels of TBX15 in ovarian carcinoma, which is the most lethal and aggressive type of gynecological tumor, in order to determine the role of TBX15 in the pathogenesis of ovarian carcinoma. This alteration could be used to predict tumor development, progression, recurrence and therapeutic effects. The study was conducted on 80 epithelial ovarian carcinoma and 17 control cases (normal ovarian and tubal tissues). TBX15 promoter methylation was first determined by pyrosequencing following bisulfite modification, then by cloning and sequencing, in order to obtain information about the epigenetic haplotype. Immunohistochemical analysis was performed to evaluate the correlation between the methylation and protein expression levels. Data revealed a statistically significant increase of the TBX15 promoter region methylation in 82% of the tumor samples and in various histological subtypes. Immunohistochemistry showed an inverse correlation between methylation levels and the expression of the TBX15 protein. Furthermore, numerous tumor samples displayed varying degrees of intratumor heterogeneity. Thus, the present study determined that ovarian carcinoma typically expresses low levels of TBX15 protein, predominantly due to an epigenetic mechanism. This may have a role in the pathogenesis of ovarian carcinoma independent of the histological subtype.
IntroductionOvarian cancer is the fourth most common type of cancer in the female genital tract, but has the highest mortality rate of all gynecological tumors. Ovarian carcinoma accounts for >90% of cases of ovarian cancer and may arise from relatively pluripotent cells of the coelomic epithelium or 'modified mesothelium' that covers the ovary (1). The coelomic epithelium is the mesodermal-derived epithelial lining of the intraembryonic coelom that invaginates to give rise to the mülllerian ducts, the primordia for the epithelia of the fallopian tube, the endometrium and the endocervix (1). There is now compelling evidence that certain carcinomas can also originate from the fallopian tubes and the endometriosis (1,2). Ovarian carcinoma are a heterogeneous group of neoplasms that exhibit a wide range of tumor morphologies and clinical manifestations (2). According to the World Health Organization classification, the most common tumor subtypes are serous, endometrioid and mucinous, and are characterized by their morphological resemblance to various mucosal tissues of the female reproductive tract (3). Cytogenetic and molecular analysis indicates that multiple genetic and epigenetic changes are involved in the pathogenesis of ovarian carcinoma (2,4); however, it remains unclear how these alterations lead to the development of ovarian cancer. Better understanding of the molecular mechanisms responsible for the diffe...