Suppression of the Epithelial-Mesenchymal Transition by Grainyhead-like-2

Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, West Virginia 26506, USA.
Cancer Research (Impact Factor: 9.33). 03/2012; 72(9):2440-53. DOI: 10.1158/0008-5472.CAN-11-4038
Source: PubMed


Grainyhead genes are involved in wound healing and developmental neural tube closure. In light of the high degree of similarity between the epithelial-mesenchymal transitions (EMT) occurring in wound-healing processes and the cancer stem cell-like compartment of tumors, including TGF-β dependence, we investigated the role of the Grainyhead gene, Grainyhead-like-2 (GRHL2) in oncogenic EMT. GRHL2 was downregulated specifically in the claudin-low subclass breast tumors and in basal-B subclass breast cancer cell lines. GRHL2 suppressed TGF-β-induced, Twist-induced or spontaneous EMT, enhanced anoikis sensitivity, and suppressed mammosphere generation in mammary epithelial cells. These effects were mediated in part by suppression of ZEB1 expression via direct repression of the ZEB1 promoter. GRHL2 also inhibited Smad-mediated transcription and it upregulated mir-200b/c as well as the TGF-β receptor antagonist, BMP2. Finally, ectopic expression of GRHL2 in MDA-MB-231 breast cancer cells triggered an MET and restored sensitivity to anoikis. Taken together, our findings define a major role for GRHL2 in the suppression of oncogenic EMT in breast cancer cells.

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    • "Reduced expression of GRHL2 in breast tumors has been associated with an EMT phenotype, increased cell survival, and migratory and invasive behaviour, which is reminiscent of a tumor suppressor gene [11] [12]. Conversely, high GRHL2 expression has been related to a poor prognosis for breast cancer metastasis [10] [11] [15] [17], although we are currently exploring the hypothesis that high expression of GRHL2 indicates a loss of function of this protein. Figure 5. GRHL2 expression at the mRNA level in cervical samples without lesions. "
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    ABSTRACT: The transcription factor grainyhead-like 2 (GRHL2) is evolutionarily conserved in many different species, and is involved in morphogenesis, epithelial differentiation, and the control of the epithelial-mesenchymal transition. It has also recently been implicated in carcinogenesis, but its role in this remains controversial. Expression of GRHL2 has not previously been reported in cervical cancer, so the present study aimed to characterize GRHL2 expression in cervical cancer-derived cell lines (CCCLs) and cervical tissues with different grades of lesions. Microarray analysis found that the expression of 58 genes was down-regulated in CCCLs compared to HaCaT cells (non-tumorigenic human epithelial cell line). The expression of eight of these genes was validated by quantitative real-time PCR (qPCR), and GRHL2 was found to be the most down-regulated. Western blot assays corroborated that GRHL2 protein levels were strongly down-regulated in CCCLs. Cervical cells from women without cervical lesions were shown to express GRHL2, while immunohistochemistry found that positivity to GRHL2 decreased in cervical cancer tissues. In conclusion, a loss or strong reduction in GRHL2 expression appears to be a characteristic of cervical cancer, suggesting that GRHL2 down-regulation is a necessary step during cervical carcinogenesis. However, further studies are needed to delineate the role of GRHL2 in cervical cancer and during malignant progression.
    Full-text · Article · Dec 2014 · International journal of clinical and experimental pathology
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    • "GRHL2 also stimulates the expression of PCNA and is generally expressed in carcinomas, but not in normal tissues [53], [54]. This highly NEC-correlated gene, which is also highly correlated with the expression of epithelial-related genes in the CCLE breast, colon, and ovarian cancer cell lines (Figures 10–13), thus may be involved in conferring proliferation capability to epithelial cancer cells, such as would occur in normal epithelial cells during wound healing [55]. "
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    ABSTRACT: Using gene expression data to enhance our knowledge of control networks relevant to cancer biology and therapy is a challenging but urgent task. Based on the premise that genes that are expressed together in a variety of cell types are likely to functions together, we derived mutually correlated genes that function together in various processes in epithelial-like tumor cells. Expression-correlated genes were derived from data for the NCI-60 human tumor cell lines, as well as data from the Broad Institute's CCLE cell lines. NCI-60 cell lines that selectively expressed a mutually correlated subset of tight junction genes served as a signature for epithelial-like cancer cells. Those signature cell lines served as a seed to derive other correlated genes, many of which had various other epithelial-related functions. Literature survey yielded molecular interaction and function information about those genes, from which molecular interaction maps were assembled. Many of the genes had epithelial functions unrelated to tight junctions, demonstrating that new function categories were elicited. The most highly correlated genes were implicated in the following epithelial functions: interactions at tight junctions (CLDN7, CLDN4, CLDN3, MARVELD3, MARVELD2, TJP3, CGN, CRB3, LLGL2, EPCAM, LNX1); interactions at adherens junctions (CDH1, ADAP1, CAMSAP3); interactions at desmosomes (PPL, PKP3, JUP); transcription regulation of cell-cell junction complexes (GRHL1 and 2); epithelial RNA splicing regulators (ESRP1 and 2); epithelial vesicle traffic (RAB25, EPN3, GRHL2, EHF, ADAP1, MYO5B); epithelial Ca(+2) signaling (ATP2C2, S100A14, BSPRY); terminal differentiation of epithelial cells (OVOL1 and 2, ST14, PRSS8, SPINT1 and 2); maintenance of apico-basal polarity (RAB25, LLGL2, EPN3). The findings provide a foundation for future studies to elucidate the functions of regulatory networks specific to epithelial-like cancer cells and to probe for anti-cancer drug targets.
    Full-text · Article · Jun 2014 · PLoS ONE
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    • "We suspected that SALL4 regulates transcription factors involving in EMT, because SALL4 knockdown induces epithelial transition. In order to identify the factor(s), we used quantitative RT-PCR to screen the transcription factors, SNAI1, SNAI2, TWIST1, TWIST2, FOXC1, FOXC2, TGFB1, TCF3, GSC, GRHL2, ZEB1 and ZEB2 [18] [19] [20]. In the result, we found reduction in the ZEB1 mRNA level in shSALL4-expressing cells (Fig. 2A), while the others were not significantly changed (Fig. 2B and Fig. S4). "
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    ABSTRACT: In cell cultures, the dispersed phenotype is indicative of the migratory ability. Here we characterized Sal-like 4 (SALL4) as a dispersion factor in basal-like breast cancer. Our shRNA-mediated SALL4 knockdown system and SALL4 overexpression system revealed that SALL4 suppresses the expression of adhesion gene CDH1, and positively regulates the CDH1 suppressor ZEB1. Cell behavior analyses showed that SALL4 suppresses intercellular adhesion and maintains cell motility after cell-cell interaction and cell division, which results in the dispersed phenotype. Our findings indicate that SALL4 functions to suppress CDH1 expression and to maintain cell dispersion in basal-like breast cancer.
    Full-text · Article · Aug 2013 · FEBS letters
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