11279

KLF8

tumor invasion and metastasis are the main causes of death from cancer. epithelial to mesenchymal transition (EMT) is a determining step for a cancer cell to progress from a noninvasive to invasive state. Kruppel-like factor 8 (KLF8) plays a key role in oncogenic transformation and is highly overexpressed in several types of invasive human cancer, including breast cancer. To understand the role of KLF8 in regulating the progression of human breast cancer, we first established stable expression of KLF8 in an immortalized normal human breast epithelial cell line. We found that KLF8 strongly induced EMT and enhanced motility and invasiveness in the cells, by analyzing changes in cell morphology and epithelial and mesenchymal marker proteins, and using cell migration and Matrigel invasion assays. Chromatin immunoprecipitations (ChIP), oligonucleotide precipitations, and promoter-reporter assays showed that KLF8 directly bound and repressed the promoter of E-cadherin independent of E boxes in the promoter and Snail expression. Aberrant elevation of KLF8 expression is highly correlated with the decrease in E-cadherin expression in the invasive human breast cancer. Blocking KLF8 expression by RNA interference restored E-cadherin expression in the cancer cells and strongly inhibited the cell invasiveness. This work identifies KLF8 as a novel EMT-regulating transcription factor that opens a new avenue in EMT research and suggests an important role for KLF8 in human breast cancer invasion and metastasis.

BACKGROUND & AIMS: The transcription factor Kruppel-like factor 8 (KLF8) has a role in tumor development, growth, and metastasis, but its role in hepatocellular carcinoma (HCC) is not clear. METHODS: KLF8 expression in human HCC cell lines and tumor tissues was measured by quantitative real-time polymerase chain reaction, immunoblot, and immunochemical analyses. The effects of KLF8 depletion or overexpression in HCC cells were observed in cultured cells and in mice. Changes in gene expression patterns in HCC cells in which levels of KLF8 were reduced using small interfering RNA were investigated by microarray analysis. The clinical significance of KLF8 expression levels were validated using tissue microarray analysis of surgical samples from 314 HCC patients. RESULTS: KLF8 was overexpressed in highly metastatic HCC cell lines and in samples from patients with recurrent HCC. In cultured cells, KLF8 up-regulation promoted cell proliferation and invasion; inhibited apoptosis; down-regulated N-cadherin, vimentin, and fibronectin; and up-regulated E-cadherin. In mice, overexpression of KLF8 increased HCC progression and metastasis. Microarray analysis showed that reduction of KLF8 in HCC cells down-regulated expression of multiple genes involved in tumor progression and metastasis. KLF8 expression was a significant predictor of overall survival (P = .040) and time to HCC recurrence (P = .006) and was associated with early tumor recurrence (P = .001). CONCLUSIONS: KLF8 promotes HCC cell proliferation and invasion, inhibits apoptosis, and induces the epithelial-to-mesenchymal transition. KLF8 up-regulation might be used to indicate poor prognosis or early recurrence of cancer in patients who have had surgery for HCC.CI - Copyright (c) 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.

Previously, we reported that hypoxia was able to induce invasion and metastasis in gastric cancer and that hypoxia-inducible factor-1 (HIF-1) is a key factor involved in this tumor type. Kruppel-like factor 8 (KLF8) as a transcriptional repressor has been suggested as a promoter of tumor metastasis in breast cancer and an inducer of the epithelialmesenchymal transition (EMT). KLF8 is also highly expressed in gastric cancer tissues, contributing to poor prognosis. However, the association between KLF8 and HIF-1 in regulating the progression of human gastric cancer in hypoxia is unclear. In the present study, we found that KLF8 was overexpressed in gastric cancer metastatic tissues and cells. Additionally, KLF8 siRNA significantly inhibited SGC7901 cell invasion and migration compared with SGC7901, SGC7901/Scr-si cells. Hypoxia is thus able to induce KLF8 expression and EMT in SGC7901 cells. However, following the examination of changes in cell morphology and epithelial and mesenchymal markers, it was found that KLF8 siRNA and HIF-1 siRNA strongly reversed EMT in cells undergoing hypoxia. Furthermore, hypoxia-induced KLF8 overexpression was attenuated by HIF-1 siRNA. Experiments using luciferase promoter constructs resulted in a marked increase in the activity of cells exposed to hypoxia and decreased activity in cells co-transfected with HIF-1 siRNA. The chromatin immunoprecipitation assay revealed proximal HRE at -133 is the main HIF-1 binding site in the KLF8 promoter. In conclusion, the results demonstrated that KLF8 is actively enhanced by hypoxia and is a novel HIF-1 target. KLF8 is a novel EMT regulating transcription factor that involved in the progression of gastric cancer. The specific anti-EMT drugs in combination with anti-hypoxia are new promising cancer therapies.

epithelial-mesenchymal transition (EMT) has been shown to be related to the pathogenesis of various diseases. Recently, microRNAs (miRNA) have been recognized as a new class of genes involved in human tumorigenesis. In this study, we found that the expression levels of miR-135a were dramatically decreased in NSCLC cell lines and clinical NSCLC tissue samples. Then, we demonstrated that miR-135a significantly suppressed the migration and invasion of lung cancer cells in vitro, suggesting that miR-135a may be a novel tumor suppressor. Further studies revealed that the transcription factor KLF8 was a target gene of miR-135a in NSCLC cells, as miR-135a bound directly to the 3'-untranslated region (3'-UTR) of KLF8, thus reducing both the expression of KLF8 at the mRNA and protein levels. In addition, the EMT marker E-cadherin or vimentin was also down-regulated or up-regulated on miR-135a treatment. Moreover, silencing KLF8 was able to inhibit the migration and invasion of lung cancer cells. In conclusion, these findings indicate that miR-135a suppresses the migration and invasion of NSCLC cells through targeting KLF8, which is involved in the EMT process. This finding provides new insight into the mechanism of NSCLC progression.CI - Copyright (c) 2015 Elsevier Inc. All rights reserved.

MicroRNAs (miRNAs) have a great effect on regulating tumor cell migration, invasion, proliferation and prognosis. However, the mechanism of miR-1236-3p on regulating carcinogenesis is still unknown. In this study, the expression of miR-1236-3p was lower in lung adenocarcinoma tissues than that in adjacent normal tissue. In lung adenocarcinoma A549 cell line, miR-1236-3p decreased ability of cell invasion and migration, furthermore, we show that KLF8 is targeted by miR-1236-3p, and expression of miR-1236-3p is negatively correlated with KLF8. Additionally, miR-1236-3p suppressed the expression of KLF8 and EMT (epithelial mesenchymal transition)-related genes. Overexpression of KLF8 can promote EMT-related genes at protein level. In conclusion, our results support the fact that miR-1236-3p acts as a tumor inhibitor in lung adenocarcinoma by suppressing the activity of KLF8, and it may play a critical role in the diagnosis and treatment of lung cancer.CI - Copyright (c) 2017. Published by Elsevier Inc.