BackgroundKlotho was originally characterized as an anti-aging gene that predisposed Klotho-deficient mice to a premature aging-like syndrome. Recently, KLOTHO was reported to function as a secreted Wnt antagonist and as a tumor suppressor. Epigenetic gene silencing of secreted Wnt antagonists is considered a common event in a wide range of human malignancies. Abnormal activation of the canonical Wnt pathway due to epigenetic deregulation of Wnt antagonists is thought to play a crucial role in cervical tumorigenesis. In this study, we examined epigenetic silencing of KLOTHO in human cervical carcinoma.ResultsLoss of KLOTHO mRNA was observed in several cervical cancer cell lines and in invasive carcinoma samples, but not during the early, preinvasive phase of primary cervical tumorigenesis. KLOTHO mRNA was restored after treatment with either the DNA demethylating agent 2'-deoxy-5-azacytidine or histone deacetylase inhibitor trichostatin A. Methylation-specific PCR and bisulfite genomic sequencing analysis of the promoter region of KLOTHO revealed CpG hypermethylation in non-KLOTHO-expressing cervical cancer cell lines and in 41% (9/22) of invasive carcinoma cases. Histone deacetylation was also found to be the major epigenetic silencing mechanism for KLOTHO in the SiHa cell line. Ectopic expression of the secreted form of KLOTHO restored anti-Wnt signaling and anti-clonogenic activity in the CaSki cell line including decreased active β-catenin levels, suppression of T-cell factor/β-catenin target genes, such as c-MYC and CCND1, and inhibition of colony growth.ConclusionsEpigenetic silencing of KLOTHO may occur during the late phase of cervical tumorigenesis, and consequent functional loss of KLOTHO as the secreted Wnt antagonist may contribute to aberrant activation of the canonical Wnt pathway in cervical carcinoma.

Abstract.A 34-KD protein encoded by the SEI-1 gene (p34 ), is a relatively recently discovered oncoprotein that has multiple important biological functions. Our data show that p34 SEI-1 enhances cancer cell survival and promotes tumorigenesis by downregulating the tumor suppressor PTEN, a negative regulator of the PI3K/AKT signaling pathway, and therefore activating the PI3K/AKT signaling pathway. In this process, p34 SEI-1 positively affects NEDD4-1 gene expression both at the transcriptional and protein levels. Furthermore, the expression levels of p34 SEI-1 and NEDD4-1 were found to be coordinated in tumor tissues obtained from patients with breast cancer. We also show that p34 SEI-1 affects the subcellular localization of PTEN.

Abstract. Aberrant activation of the Wnt/β-catenin signaling pathway is common in human cervical cancers. However, the mechanisms of Wnt activation in cervical cancer remain largely unknown. In the present study, we demonstrate that Klotho, a Wnt antagonist, is downregulated in invasive human cervical tumors and in a cell line we analyzed. Our data demonstrated that in vivo Klotho expression was not observed in invasive cervical carcinoma. In vitro restoration of Klotho expression in SiHa cells resulted in a decreased cell motility and invasiveness through upregulation of E-cadherin, downregulation of N-cadherin and reduced expression of MMP7 and -9. Ectopic expression of Klotho also reduced the expression of the epithelial-to-mesenchymal transition (EMT) transcription factors Slug and Twist. Furthermore, Klotho causes a significant inhibition of the Wnt/β-catenin pathway in cervical cancer cells, as supported by the expression of Wnt/β-catenin transcriptional target genes such as c-Myc and cyclin D1. Consequently, our findings demonstrate for the first time that Klotho regulates tumor invasion through the EMT process and provide novel mechanistic insights into the role of Klotho in cervical cancer progression and contribute to treatment for metastatic cervical cancer patients. IntroductionCervical carcinoma is one of the most common cancers and the second-leading cause of cancer deaths in women worldwide (1). Substantial research has been performed to identify the causative agents for development of cervical cancer and now it is generally accepted that human papilloma virus (HPV) is the principal etiological agent of cervical cancer (2). Although the virus infecting these tumors can immortalize human cells, it does not result in transformation. Therefore, HPV infection is likely to be necessary, but insufficient for developing cervical cancers. It might mean there are factors epigenetic, genetic, cellular, and environmental that can influence carcinogenesis (3). Although the precise molecular mechanisms are still unclear, the most possible signaling pathways that is considered as the second hit in the multistep process of cervical carcinogenesis caused by HPV is the Wingless-type (Wnt)/β-catenin pathway (4,5).The Wnt pathway is an important regulator in the control of several biological processes such as proliferation and differentiation in embryogenesis, regulation of the cell cycle, tissue homeostasis in adult tissue and tumor progression (6). Wnt ligands binding to its receptor complex comprised of Frizzled/ low-density lipoprotein receptor-related protein (Fz/LRP) trigger a canonical pathway. In this pathway, β-catenin was stabilized by inhibition of its phosphorylation and subsequent proteosomal degradation. Stabilized β-catenin translocates to the nucleus and forms a complex with T-cell factor/lymphoid enhancer factor (TCF/LEF) to activate target genes (7). In contrast, Wnt inhibition caused by its antagonists leads to decreased accumulation of cytosolic and nuclear β-catenin with consequent downregulatio...

TRIP-Br1 oncogenic protein has been shown to have multiple biological functions in cells. In this study, we demonstrate that TRIP-Br1 functions as an oncoprotein by inhibiting autophagy, apoptosis, and necroptosis of cancer cells and eventually helping them to survive under the nutrient/serum starved condition. TRIP-Br1 expression level was significantly increased in conditions with low levels of nutrients. Nutrient depleted conditions were induced by culturing cancer cells until they were overcrowded with high cell density or in media deprived of glucose, amino acids, or serum. Among them, serum starvation significantly enhanced the expression of TRIP-Br1 only in all tested breast cancer cell lines (MCF7, MDA-MB-231, T47D, MDA-MB-435, Hs578D, BT549, and MDA-MB-435) but not in the three normal cell lines (MCF10A, HfCH8, and NIH3T3). As compared with the control cells, the introduction of TRIP-Br1 silencing siRNA into MCF7 and MDA-MB-231 cells accelerated cell death by inducing apoptosis and necroptosis. In this process, TRIP-Br1 confers resistance to serum starvation-induced cell deaths by stabilizing the XIAP protein and inhibiting cellular ROS production. Moreover, our data also show that the intracellular increase of TRIP-Br1 protein resulting from serum starvation seems to occur in part through the blockage of PI3K/AKT signaling pathway.

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