7528

YY1

YY1 transcription factor;YY1;YY1 transcription factor

INO80 complex subunit S|YY-1|Yin and Yang 1 protein|delta transcription factor|transcriptional repressor protein YY1

14q

protein-coding

The majority of cancers develop genetic and molecular strategies to resist conventional cytotoxic therapies as well as escape from the host's immune surveillance. These events lead to tumor persistence and spread through activation of the epithelial to mesenchymal transition (EMT) program and metastasis. expression profiling analysis has revealed various tumor metastasis-inducing and metastasis-suppressing genes that regulate the metastatic process and maintain the microenvironment of the tumor cells. EMT in cancer entails the molecular reprogramming and phenotypic changes that characterize the conversion of immobile cancer epithelial cells to motile mesenchymal cells. A hallmark of EMT is the loss of E-cadherin, the epithelial homotypic adhesion molecule, and gain of mesenchymal markers such as vimentin and fibronectin. The molecular mechanisms underlying the initiation of EMT consist, in part, in the constitutive activation of survival signaling pathways such as the nuclear factor (NF)-kappaB pathway. The NF-kappaB pathway has been implicated directly in the regulation of EMT and indirectly through the transcription and expression of several gene products that participate in the EMT cascade, such as Snail, the metastasis-inducer and E-cadherin suppressor transcription factor. In turn, Snail represses the metastasis-suppressor gene product Raf-kinase inhibitor protein (RKIP) that inhibits both the Raf-1/MEK/ERK and NF-kappaB survival pathways implicated in EMT. Consequently, tumor cells normally exhibit a dysregulated NF-kappaB/Snail/RKIP circuitry that is intimately involved in the initiation of EMT and maintenance of drug resistance. Additional deregulated gene products in this circuit, such as the metastasis-suppressor phosphatase and tensin homologue (PTEN; repressed by Snail) and the putative-metastasis inducer Yin Yang (YY) 1 (target of NF-kappaB) also have been associated in the regulation of EMT. We recently have investigated the direct role of YY1 in the regulation of EMT. This review discusses the molecular regulation of EMT in cancer cells through the activity of the dysregulated NF-kappaB/Snail/ YY1/PTEN/RKIP circuitry. In addition, we propose YY1 as a potential novel prognostic biomarker for EMT and a therapeutic target for both the prevention of metastasis and the reversal of resistance.

We know that the Yin Yang 1 protein (YY1) overexpression is positively and strongly correlated with the degree of malignancy of bone tumors. Therefore, we questioned whether we could influence cell invasiveness by deleting YY1 in human osteosarcoma cells (SaOs-2), as tested in Matrigel-coated filters and metastasis implantation of such osteosarcoma cells in vivo, by serial analysis with nuclear magnetic resonance. Moreover, we focused our work on the chemokine receptor CXCR4 and its inhibition by T22 antibody, as well as on systemic (direct in vivo assay) and computer-assisted imaging of angiogenesis-related metastasis. Results showed that cell invasiveness and metastasis implantation by wild-type SaOs-2 cells, as evaluated by histology and immunohistochemistry, are associated with up-regulation of CXCR4 expression, which in turn was significantly reduced by T22. In addition, deletion of YY1 (siRNAYY1-SaOs-2) induced a significant decrease of cell invasion and metastasis growth. This phenomenon was associated with decreased vascular endothelial growth factor (VEGF)/angiogenesis and a complex rearrangement of the gene expression profile as evaluated by microarray analysis. In conclusion, YY1 and VEGF/CXCR4 seem to intervene in the pathogenesis of the malignant phenotype of osteosarcoma by acting on cell invasiveness and metastasis growth.

The transcription repressor Yin Yang 1 (YY1) is expressed in several human cancer cell lines and its expression correlates with resistance to immune-mediated apoptosis. This study used tissue microarrays to investigate the expression and localization of YY1 in 1364 representative tissue samples from 246 hormone naive prostate cancer patients who underwent radical prostatectomy. Staining intensity and frequency measures for both YY1 nuclear and cytoplasmic expression were higher in neoplastic tissues and in PIN samples compared to matched benign cells (p < 0.0001 for all comparisons). expression of YY1 is predominantly elevated in early malignancy (PIN), as well as in tumors of intermediate to high morphologic grade (Gleason's grade 3-5). Using multivariate Cox proportional hazards analysis, we observed that low nuclear YY1 staining is an independent predictor of a shorter time to recurrence (p = 0.012). Based on these results, we hypothesize that YY1 may play a role in prostate cancer development; however, decreased YY1 may give metastatic cells a survival advantage. These results may also implicate YY1 as a useful diagnostic and prognostic marker.