Ression was assessed (green). Blue = DAPI; red = phallodin. Western blot and confocal microscopy data is representative of at least three independent experiments. *p,0,05 (N = 36SD). doi:10.1371/journal.pone.0053238.gbe involved in embryonic and tumorigenic processes mediated by these signaling events [17,19,29,30]. Similar to TGF-b, SOX4 has a paradoxical function in tumorigenesis potentially acting as both a tumor-suppressor andpromoter of tumor progression [25]. High levels of SOX4 mRNA 1418741-86-2 expression are present in nearly all major human cancers and SOX4 has been recognized as one of the 64 cancer signature genes [31]. Despite its elevated expression in human cancers, theSOX4 Affects Mesenchymal Genes in TGFb Induced EMTtranscriptional changes mediated by SOX4 remain poorly defined. A number of studies have investigated SOX4 mediated transcriptional changes in the context of prostate, hepatocellular carcinoma (HCC), small cell lung cancer 12926553 and adenoid cystic carcinoma, resulting in the identification of a large number of potential SOX4 targets [32,33,34,35]. However, it remains to be determined whether most of the identified genes are indeed direct transcriptional targets of SOX4 or are the result of secondary events. Additionally, there is very little overlap in the transcriptional targets identified in different tumors, suggesting that, similar to TGF-b, the transcriptional response initiated by SOX4 is highly context dependent. SOX4 has also been demonstrated to contribute to cancer progression and metastasis in breast cancer glioma and HCC. Similar to breast cancer, HCC metastasis can be driven by TGF-b through EMT induced phenotypic changes [36]. In HCC, SOX4 expression is greatly elevated in metastatic tumors compared to their non-metastatic counterparts, and shRNA-mediated SOX4 knockdown in metastatic HCC cells significantly reduced tumor metastasis [35]. In K162 addition to the reduced metastatic capacity, SOX4 knockdown HCC cells were observed to have alterations in cell morphology and showed decreased expression of the mesenchymal markers vimentin, suggesting that shRNA-mediated reduction in the expression of SOX4 in metastatic HCC cells reverts their mesenchymal phenotype to an epithelial phenotype through a mesenchymal to epithelial transition (MET) [35]. SOX4 has been demonstrated to be a downstream target of the TGF-b signaling pathway in a number of cell types including T-helper cells and glioma [37,38]. In glioma, SOX4 expression is directly induced by TGF-b activated SMAD2/3, resulting in the maintenance of sternness and tumorigenicity [37]. Interestingly, SOX4 expression is also increased in normal mammary stem cells, and together with other mammary stem cells markers identifies the cancer stem cell content of breast cancers [39]. Similarly, induction of EMT in breast cancers generates increased stem cell content and confers stem cell properties [3]. It is thus possible that similar to glioma, TGF-b-induced breast cancer stem cells properties are mediated by SOX4, suggesting that SOX4 induction might impact on multiple aspects of the EMT phenotype. Indeed, a recent study has shown that SOX4 promotes EMT in immortalized human mammary epithelial cell line MCF10A, which was associated with a mesenchymal phenotype, enhanced stem cell properties, increased cellular migration and invasion in vitro and increased RAS induced tumorigenesis in vivo [40]. Additionally, SOX4 was demonstrated to be positively regulated by TGF-b and was e.Ression was assessed (green). Blue = DAPI; red = phallodin. Western blot and confocal microscopy data is representative of at least three independent experiments. *p,0,05 (N = 36SD). doi:10.1371/journal.pone.0053238.gbe involved in embryonic and tumorigenic processes mediated by these signaling events [17,19,29,30]. Similar to TGF-b, SOX4 has a paradoxical function in tumorigenesis potentially acting as both a tumor-suppressor andpromoter of tumor progression [25]. High levels of SOX4 mRNA expression are present in nearly all major human cancers and SOX4 has been recognized as one of the 64 cancer signature genes [31]. Despite its elevated expression in human cancers, theSOX4 Affects Mesenchymal Genes in TGFb Induced EMTtranscriptional changes mediated by SOX4 remain poorly defined. A number of studies have investigated SOX4 mediated transcriptional changes in the context of prostate, hepatocellular carcinoma (HCC), small cell lung cancer 12926553 and adenoid cystic carcinoma, resulting in the identification of a large number of potential SOX4 targets [32,33,34,35]. However, it remains to be determined whether most of the identified genes are indeed direct transcriptional targets of SOX4 or are the result of secondary events. Additionally, there is very little overlap in the transcriptional targets identified in different tumors, suggesting that, similar to TGF-b, the transcriptional response initiated by SOX4 is highly context dependent. SOX4 has also been demonstrated to contribute to cancer progression and metastasis in breast cancer glioma and HCC. Similar to breast cancer, HCC metastasis can be driven by TGF-b through EMT induced phenotypic changes [36]. In HCC, SOX4 expression is greatly elevated in metastatic tumors compared to their non-metastatic counterparts, and shRNA-mediated SOX4 knockdown in metastatic HCC cells significantly reduced tumor metastasis [35]. In addition to the reduced metastatic capacity, SOX4 knockdown HCC cells were observed to have alterations in cell morphology and showed decreased expression of the mesenchymal markers vimentin, suggesting that shRNA-mediated reduction in the expression of SOX4 in metastatic HCC cells reverts their mesenchymal phenotype to an epithelial phenotype through a mesenchymal to epithelial transition (MET) [35]. SOX4 has been demonstrated to be a downstream target of the TGF-b signaling pathway in a number of cell types including T-helper cells and glioma [37,38]. In glioma, SOX4 expression is directly induced by TGF-b activated SMAD2/3, resulting in the maintenance of sternness and tumorigenicity [37]. Interestingly, SOX4 expression is also increased in normal mammary stem cells, and together with other mammary stem cells markers identifies the cancer stem cell content of breast cancers [39]. Similarly, induction of EMT in breast cancers generates increased stem cell content and confers stem cell properties [3]. It is thus possible that similar to glioma, TGF-b-induced breast cancer stem cells properties are mediated by SOX4, suggesting that SOX4 induction might impact on multiple aspects of the EMT phenotype. Indeed, a recent study has shown that SOX4 promotes EMT in immortalized human mammary epithelial cell line MCF10A, which was associated with a mesenchymal phenotype, enhanced stem cell properties, increased cellular migration and invasion in vitro and increased RAS induced tumorigenesis in vivo [40]. Additionally, SOX4 was demonstrated to be positively regulated by TGF-b and was e.
