Grhl2 determines the epithelial phenotype of breast cancers and promotes tumor progression.
ABSTRACT: Until now the essential transcription factor that determines the epithelial phenotype of breast cancer has not been identified and its role in epithelial-to-mesenchymal transition (EMT) and tumor progression remain unclear. Here, by analyzing large expression profiles of human breast cancer cells, we found an extraordinary correlation between the expression of Grainyhead transcription factor Grhl2 and epithelial marker E-cadherin. Knockdown of Grhl2 expression by shRNA in human mammary epithelial cell MCF10A leads to down-regulation of E-cadherin and EMT. Grhl2 is down-regulated in disseminated cancer cells that have undergone EMT, and over-expression of Grhl2 is sufficient to induce epithelial gene expression. Large clinical datasets reveal that expression of Grhl2 is significantly associated with poor relapse free survival and increased risk of metastasis in breast cancer patients. In mouse models, over-expression of Grhl2 significantly promotes tumor growth and metastasis. Further testing of several Grhl2 regulated genes leads to the same conclusions that the tumorigenic and metastatic potentials of tumor cells are linked to epithelial phenotype but not mesenchymal phenotype. In conclusion, our findings indicate that Grhl2 plays an essential role in the determination of epithelial phenotype of breast cancers, EMT and tumor progression.
Project description:Epithelial-mesenchymal transition (EMT), a biological process by which polarized epithelial cells convert into a mesenchymal phenotype, has been implicated to contribute to the molecular heterogeneity of epithelial ovarian cancer (EOC). Here we report that a transcription factor--Grainyhead-like 2 (GRHL2) maintains the epithelial phenotype. EOC tumours with lower GRHL2 levels are associated with the Mes/Mesenchymal molecular subtype and a poorer overall survival. shRNA-mediated knockdown of GRHL2 in EOC cells with an epithelial phenotype results in EMT changes, with increased cell migration, invasion and motility. By ChIP-sequencing and gene expression microarray, microRNA-200b/a is identified as the direct transcriptional target of GRHL2 and regulates the epithelial status of EOC through ZEB1 and E-cadherin. Our study demonstrates that loss of GRHL2 increases the levels of histone mark H3K27me3 on promoters and GRHL2-binding sites at miR-200b/a and E-cadherin genes. These findings support GRHL2 as a pivotal gatekeeper of EMT in EOC via miR-200-ZEB1.
Project description:Our previous study has demonstrated that knockdown of Grainyhead-like 2(GRHL2) in colorectal cancer (CRC) cells inhibited cell proliferation by targeting ZEB1. This study aimed at researching whether knockdown of GRHL2 promoted CRC progression and metastasis via inducing epithelial-mesenchymal transition (EMT). GRHL2-upregulated SW-620/GRHL2+ and GRHL2-knockdown HCT116/GRHL2-KD, HT29/GRHL2-KD cells and their control cells were generated. The morphological changes after overexpression and knockdown GRHL2 were observed. qRT-PCR, Western blotting, and Immunofluorescence were used to detect EMT markers: E-cadherin, Vimentin, p-catein, ZO-1 and ZEB1 expression. Then, sh-ZEB1 was transfected to GRHL2 knockdown cells to research the relationship between GRHL2 and ZEB1. Transwell and wound healing assays were further performed to detect the impact of GRHL2 on invasion and migration in vitro. CRC cells were injected into mice tail vein to verify the impact of GRHL2 on CRC metastasis. Morphological change of mesenchymal-epithelial transition (MET) could be observed in SW620/GRHL2+ cell. The expression of epithelial markers: E-cadherin, ?-catenin, ZO-1 were up-regulated, while mesenchymal markers: Vimentin was decreased. Meanwhile, opposite EMT morphological change could be observed in HCT116/GRHL2-KD cell, accompanied by reverse change of E-cadherin, ?-catenin, ZO-1, and Vimentin. The expression level of GRHL2 and ZEB1 was found negative in both SW620/GRHL2+ and HCT116/GRHL2-KD cells. Knockdown of ZEB1 by siRNA in HCT116/GRHL2-KD and HT29/GRHL2-KD could upregulate expression of E-cadherin and GRHL2. GRHL2 knockdown also promoted migration, invasion in vitro and CRC metastasis in mice model. In conclusion, GRHL2/ZEB1 axis inhibits CRC progression and metastasis via oppressing EMT.
Project description:The epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) contribute to cancer metastasis of pancreatic ductal adenocarcinoma (PDAC). We explored the role of grainyhead-like 2 (GRHL2), a suppressor of EMT, in the progression of PDAC. Expressions of GRHL2 were assessed using surgically resected PDAC tissues by immunohistochemistry analysis, and in vitro using human and mouse PDAC cells. Effects on epithelial plasticity and stemness of GRHL2 were examined in vitro using liver metastatic PDAC cells (CFPAC-1) with GRHL2 knockdown by specific siRNAs. GRHL2 has a significantly positive correlation with E-cadherin and CD133 in 155 resected human primary PDAC tissues. GRHL2 is highly expressed in liver metastatic cells than in primary invasive cells of both human and mouse PDAC, accompanied by a positive correlation with E-cadherin expression. GRHL2 knockdown CFPAC-1 cells demonstrated morphological changes into mesenchymal appearances and reduced proliferation through EMT. Notably, knockdown studies followed by flow cytometry analysis for a subpopulation of CD133+ showed that GRHL2 facilitates CFPAC-1 cells to maintain stem-like characters including self-renewal capacity and anoikis resistance. GRHL2 regulates epithelial plasticity along with stemness in PDAC, both of which are crucial for metastasis, implicating the possibility of GRHL2 as a therapeutic target for PDAC liver metastasis.
Project description:Using a retrovirus-mediated cDNA expression cloning approach, we identified the grainyhead-like 2 (GRHL2) transcription factor as novel protooncogene. Overexpression of GRHL2 in NIH3T3 cells induced striking morphological changes, an increase in cell proliferation, anchorage-independent growth, and tumor growth in vivo. By combining a microarray analysis and a phylogenetic footprinting analysis with various biochemical assays, we identified the epidermal growth factor receptor family member Erbb3 as a novel GRHL2 target gene. In breast cancer cell lines, shRNA-mediated knockdown of GRHL2 expression or functional inactivation of GRHL2 using dominant negative GRHL2 proteins induces down-regulation of ERBB3 gene expression, a striking reduction in cell proliferation, and morphological and phenotypical alterations characteristic of an epithelial-to-mesenchymal transition (EMT), thus implying contradictory roles of GRHL2 in breast carcinogenesis. Interestingly, we could further demonstrate that expression of GRHL2 is directly suppressed by the transcription factor zinc finger enhancer-binding protein 1 (ZEB1), which in turn is a direct target for repression by GRHL2, suggesting that the EMT transcription factors GRHL2 and ZEB1 form a double negative regulatory feedback loop in breast cancer cells. Finally, a comprehensive immunohistochemical analysis of GRHL2 expression in primary breast cancers showed loss of GRHL2 expression at the invasive front of primary tumors. A pathophysiological relevance of GRHL2 in breast cancer metastasis is further demonstrated by our finding of a statistically significant association between loss of GRHL2 expression in primary breast cancers and lymph node metastasis. We thus demonstrate a crucial role of GRHL2 in breast carcinogenesis.
Project description:Epithelial-mesenchymal transition (EMT) in carcinoma cells enhances malignant progression by promoting invasion and survival. EMT is induced by microenvironmental factors, including TGF-? and Wnt agonists, and by the E-box-binding transcription factors Twist, Snail, and ZEB. Grainyhead-like-2 (GRHL2), a member of the mammalian Grainyhead family of wound-healing regulatory transcription factors, suppresses EMT and restores sensitivity to anoikis by repressing ZEB1 expression and inhibiting TGF-? signaling. In this study, we elucidate the functional relationship between GRHL2 and ZEB1 in EMT/MET and tumor biology. At least three homeodomain proteins, Six1, LBX1, and HoxA5, transactivated the ZEB1 promoter, in the case of Six1, through direct protein-promoter interaction. GRHL2 altered the Six1-DNA complex, inhibiting this transactivation. Correspondingly, GRHL2 expression prevented tumor initiation in xenograft assays, sensitized breast cancer cells to paclitaxel, and suppressed the emergence of CD44(high)CD24(low) cells (defining the cancer stem cell phenotype in the cell type studied). GRHL2 was downregulated in recurrent mouse tumors that had evolved to an oncogene-independent, EMT-like state, supporting a role for GRHL2 downregulation in this phenotypic transition, modeling disease recurrence. The combination of TGF-? and Wnt activation repressed GRHL2 expression by direct interaction of ZEB1 with the GRHL2 promoter, inducing EMT. Together, our observations indicate that a reciprocal feedback loop between GRHL2 and ZEB1 controls epithelial versus mesenchymal phenotypes and EMT-driven tumor progression.
Project description:Epithelial ovarian cancer (EOC) is clinically heterogeneous, comprising different histological and biological subtypes. Multiple studies have implicated epithelial-mesenchymal transition (EMT), a biological process by which polarized epithelial cells convert into a mesenchymal phenotype, to contribute significantly to this molecular heterogeneity of EOC. From gene expression analyses of a collection of EMT-characterized EOC cell lines, we found that the expression of the transcription factor Grainyhead-like 2 (GRHL2) correlates with E-cadherin expression and the epithelial phenotype. EOC tumors with lower levels of GRHL2 are associated with the Mes (mesenchymal) molecular subtype and show poorer overall survival in patients. Here, we demonstrate that shRNA-mediated knockdown of GRHL2 in EOC cells with an epithelial phenotype resulted in EMT changes, with increased cell migration, invasion and motility. By ChIP-sequencing and gene expression microarray, we identified a variety of target genes regulated by GRHL2, including protein-coding and non-coding genes. Our data suggest that GRHL2 maintains the epithelial phenotype of EOC cells through the regulatory networks of miR-200b/a, ZEB1 and E-cadherin. These findings support GRHL2 as a crucial player in the molecular heterogeneity of EOC. 7 samples were analyzed (shNon control in duplicates; shGRHL2 #10 in duplicates, shGRHL2 #12 in triplicates)
Project description:Epithelial ovarian cancer (EOC) is clinically heterogeneous, comprising different histological and biological subtypes. Multiple studies have implicated epithelial-mesenchymal transition (EMT), a biological process by which polarized epithelial cells convert into a mesenchymal phenotype, to contribute significantly to this molecular heterogeneity of EOC. From gene expression analyses of a collection of EMT-characterized EOC cell lines, we found that the expression of the transcription factor Grainyhead-like 2 (GRHL2) correlates with E-cadherin expression and the epithelial phenotype. EOC tumors with lower levels of GRHL2 are associated with the Mes (mesenchymal) molecular subtype and show poorer overall survival in patients. Here, we demonstrate that shRNA-mediated knockdown of GRHL2 in EOC cells with an epithelial phenotype resulted in EMT changes, with increased cell migration, invasion and motility. By ChIP-sequencing and gene expression microarray, we identified a variety of target genes regulated by GRHL2, including protein-coding and non-coding genes. Our data suggest that GRHL2 maintains the epithelial phenotype of EOC cells through the regulatory networks of miR-200b/a, ZEB1 and E-cadherin. These findings support GRHL2 as a crucial player in the molecular heterogeneity of EOC. Overall design: 3 samples were analyzed (GRHL2 ChIP sample for 3 cell lines)
Project description:Cancer cells exhibit phenotypic plasticity during epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) involving intermediate states. To study genome-wide epigenetic remodeling associated with EMT plasticity, we integrate the analyses of DNA methylation, ChIP-sequencing of five histone marks (H3K4me1, H3K4me3, H3K27Ac, H3K27me3 and H3K9me3) and transcriptome profiling performed on ovarian cancer cells with different epithelial/mesenchymal states and on a knockdown model of EMT suppressor Grainyhead-like 2 (GRHL2). We have identified differentially methylated CpG sites associated with EMT, found at promoters of epithelial genes and GRHL2 binding sites. GRHL2 knockdown results in CpG methylation gain and nucleosomal remodeling (reduction in permissive marks H3K4me3 and H3K27ac; elevated repressive mark H3K27me3), resembling the changes observed across progressive EMT states. Epigenetic-modifying agents such as 5-azacitidine, GSK126 and mocetinostat further reveal cell state-dependent plasticity upon GRHL2 overexpression. Overall, we demonstrate that epithelial genes are subject to epigenetic control during intermediate phases of EMT/MET involving GRHL2.
Project description:Cleft lip and palate are common birth defects resulting from failure of the facial processes to fuse during development. The mammalian grainyhead-like (Grhl1-3) genes play key roles in a number of tissue fusion processes including neurulation, epidermal wound healing and eyelid fusion. One family member, Grhl2, is expressed in the epithelial lining of the first pharyngeal arch in mice at embryonic day (E)10.5, prompting analysis of the role of this factor in palatogenesis. Grhl2-null mice die at E11.5 with neural tube defects and a cleft face phenotype, precluding analysis of palatal fusion at a later stage of development. However, in the first pharyngeal arch of Grhl2-null embryos, dysregulation of transcription factors that drive epithelial-mesenchymal transition (EMT) occurs. The aberrant expression of these genes is associated with a shift in RNA-splicing patterns that favours the generation of mesenchymal isoforms of numerous regulators. Driving the EMT perturbation is loss of expression of the EMT-suppressing transcription factors Ovol1 and Ovol2, which are direct GRHL2 targets. The expression of the miR-200 family of microRNAs, also GRHL2 targets, is similarly reduced, resulting in a 56-fold upregulation of Zeb1 expression, a major driver of mesenchymal cellular identity. The critical role of GRHL2 in mediating cleft palate in Zeb1-/- mice is evident, with rescue of both palatal and facial fusion seen in Grhl2-/-;Zeb1-/- embryos. These findings highlight the delicate balance between GRHL2/ZEB1 and epithelial/mesenchymal cellular identity that is essential for normal closure of the palate and face. Perturbation of this pathway may underlie cleft palate in some patients.
Project description:Previous reports have associated GRHL2 with tumor progression. However, the biological role of GRHL2 in human colorectal cancer (CRC) has not been explored. We examined the expression of GRHL2 in 75 CRC samples, as well as the paired non-tumor tissues, by immunohistochemistry, qRT-PCR, and western blot analysis. The association between GRHL2 expression and various clinicopathological parameters including Ki-67, a marker of proliferative activity, was also evaluated. We performed lentivirus-mediated shRNA transfection to knock down GRHL2 gene expression in HT29 and HCT116 CRC cells. Cell proliferation was examined by the CCK-8 (Cell Counting Kit-8) assay, colony formation, and cell cycle assay in vitro. Tumorigenesis in vivo was assessed using a mouse xenograft model. Moreover, we transiently silenced ZEB1 expression in GRHL2-knockdown CRC cells using specific shRNA, and then examined the effects on GRHL2 and E-cadherin expression, as well as cell proliferation. Herein, we demonstrated that enhanced GRHL2 expression was detected in CRC, and correlated with higher levels of Ki-67 staining, larger tumor size, and advanced clinical stage. Knocking down GRHL2 in HT29 and HCT116 CRC cells significantly inhibited cell proliferation by decreasing the number of cells in S phase and increasing that in the G 0/G 1 phaseof the cell cycle. This resulted in inhibition of tumorigenesis in vivo, as well as increased expression of ZEB1. Furthermore, transient ZEB1 knockdown dramatically enhanced cell proliferation and increased GRHL2 and E-cadherin expression. Collectively, our study has identified ZEB1 as a target of GRHL2 and suggested a reciprocal GRHL2-ZEB1 repressive relationship, providing a novel mechanism through which proliferation may be modulated in CRC cells.