KLF8 promotes tumorigenesis, invasion and metastasis of colorectal cancer cells by transcriptional activation of FHL2

Predicting progression-free survival using dynamic contrast-enhanced imaging-based radiomics in advanced nasopharyngeal carcinoma patients treated with nimotuzumab

PURPOSE

The purpose of this study was to explore the potential value of the radiomics model based on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), compared with the clinical model mostly based on the epidermal growth factor receptor (EGFR) expression, in predicting progression-free survival (PFS) in patients with locally advanced nasopharyngeal carcinoma (LA-NPC) treated with nimotuzumab (NTZ).

METHODS

A total of 136 patients with LA-NPC who received NTZ treatment between January 2018 and June 2022 were included in this study. Patients were randomly divided into training (n = 95) and validation (n = 41) groups in a 7:3 ratio. DCE-MRI radiomics, clinical, and clinical-radiomics models were built to predict PFS. The relationship between EGFR expression levels and NTZ efficacy was assessed using Kaplan-Meier curves. Model performance was assessed using the area under the curve, calibration, and DeLong tests. Decision curve analysis evaluated net clinical benefit. Patients were stratified into high- and low-risk groups based on optimal model radiomic scores, and prognoses were compared using Kaplan-Meier curves.

RESULTS

Univariate Cox regression analysis demonstrated that EGFR expression level was the only independent predictive factor of PFS (p < 0.05). Patients with EGFR 3+ receiving NTZ therapy had significantly longer PFS than those with EGFR 1+ (hazard ratio = 3.025, p < 0.05). The clinical-radiomics model exhibited superior predictive efficacy, compared with the radiomics and clinical models (training set: 0.887 vs. 0.845, 0.654; validation set: 0.831, 0.824 vs. 0.567, all p < 0.001).

CONCLUSIONS

The clinical-radiomics models using DCE-MRI and EGFR levels can effectively predict NTZ efficacy in LA-NPC patients, providing objective evidence for personalized treatment adjustments.

KEY POINTS

Question How can the response to nimotuzumab treatment in patients with locally advanced nasopharyngeal carcinoma be accurately predicted using non-invasive imaging methods? Findings A combined clinical and radiomic model using dynamic contrast-enhanced magnetic resonance imaging showed improved predictive performance for progression-free survival in patients treated with nimotuzumab. Clinical relevance The study provides evidence for using a combined clinical and radiomic approach, offering a non-invasive method to predict treatment response and guide personalized treatment strategies for patients with locally advanced nasopharyngeal carcinoma, potentially improving patient outcomes.

The pan-cancer landscape presented ITGA7 as a prognostic determinant, tumor suppressor, and oncogene in multiple tumor types

Integrin α7 (ITGA7) is an extracellular matrix-binding protein. Integrins are the main type of cell adhesive molecules in mammals, playing a role in many biological pathways. Although various studies have shown correlations between ITGA7 and various types of cancer, a comprehensive study at a pan-cancer level has not yet been conducted. In this study, we investigated the function of ITGA7 in distinct tumor types using the multi-omics relevant information, then two CeRNA regulatory network was drawn to identify the ITGA7 hub regulatory RNAs. The results indicated that the expression of ITGA7 varies in different tumors. Overexpression of ITGA7 was correlated with a worse OS in BLCA, LGG, and UVM, and the downregulation of ITGA7 was related to a worse OS in PAAD. In addition, BLCA, and UVM showed poor PFS in association with ITGA7 overexpression, and PAAD, SARC, and THCA indicated poor PFS in correlation with ITGA7 under expression. Further analyses of ITGA7 gene alteration data showed that ITGA7 amplifications may have an impact on Kidney Chromophobe prognosis. In 20 types of tumors, ITGA7 expression was linked to cancer-associated fibroblast infiltration. ITGA7 expression was linked to cancer-associated fibroblast infiltration. ITGA7-Related Gene Enrichment Analysis indicated that ITGA7 expression-correlated and functional binding genes were enriched in homotypic cell-cell adhesion, focal adhesion, and ECM-receptor interaction. This pan-cancer study found that abnormal expression of ITGA7 was correlated with poor prognosis and metastasis in different types of tumors. Thus, the ITGA7 gene may prove to be a promising biomarker for the prognosis and complication prevention of different cancers.

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models

Interactions between tumor and stromal cells are well known to play prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs, though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use time lapse imaging and image analysis to study how co-culture geometry impacts interactions between epithelial and stromal cells. We show that extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1) result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility. We analyze these interactions in co-cultures using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. We further contrast co-cultures of PANC1 with those containing a drug resistant subline (PANC1-OR) previously established in our lab and find that heterotypic cell-cell interactions are suppressed in the latter relative to the parental line. We use RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also correlated with reduction in the hetrotypic cell-cell contact necessary for the contractile behavior observed in drug naïve cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models

Interactions between tumor and stromal cells are well known to play a prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs. Though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use 3D co-culture geometries to recapitulate juxtacrine interactions between epithelial and stromal cells. In particular, extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1), result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility which leads to highly condensed macroscopic multicellular aggregates as detected using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. To investigate how drug resistance impacts these juxtacrine interactions we contrast cultures in which PANC1 are substituted with a drug resistant subline (PANC1-OR) previously established in our lab. We find that heterotypic cell-cell interactions are highly suppressed in drug-resistant cells relative to the parental PANC1 cells. To investigate further we conduct RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also consistent with loss of hetrotypic cell-cell contact necessary for the contractile behavior observed in drug naïve cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

The roles of FHL2 in cancer

LIM domain protein 2, also known as LIM protein FHL2, is a member of the LIM-only family. Due to its LIM domain protein characteristics, FHL2 is capable of interacting with various proteins and plays a crucial role in regulating gene expression, cell growth, and signal transduction in muscle and cardiac tissue. In recent years, mounting evidence has indicated that the FHLs protein family is closely associated with the development and occurrence of human tumors. On the one hand, FHL2 acts as a tumor suppressor by down-regulating in tumor tissue and effectively inhibiting tumor development by limiting cell proliferation. On the other hand, FHL2 serves as an oncoprotein by up-regulating in tumor tissue and binding to multiple transcription factors to suppress cell apoptosis, stimulate cell proliferation and migration, and promote tumor progression. Therefore, FHL2 is considered a double-edged sword in tumors with independent and complex functions. This article reviews the role of FHL2 in tumor occurrence and development, discusses FHL2 interaction with other proteins and transcription factors, and its involvement in multiple cell signaling pathways. Finally, the clinical significance of FHL2 as a potential target in tumor therapy is examined.

Kruppel-like factor 8 regulates triple negative breast cancer stem cell-like activity

Introduction

Breast tumor development is regulated by a sub-population of breast cancer cells, termed cancer stem-like cells (CSC), which are capable of self-renewing and differentiating, and are involved in promoting breast cancer invasion, metastasis, drug resistance and relapse. CSCs are highly adaptable, capable of reprogramming their own metabolism and signaling activity in response to stimuli within the tumor microenvironment. Recently, the nutrient sensor O-GlcNAc transferase (OGT) and O-GlcNAcylation was shown to be enriched in CSC populations, where it promotes the stemness and tumorigenesis of breast cancer cells in vitro and in vivo. This enrichment was associated with upregulation of the transcription factor Kruppel-like-factor 8 (KLF8) suggesting a potential role of KLF8 in regulating CSCs properties.

Methods

Triple-negative breast cancer cells were genetically modified to generate KLF8 overexpressing or KLF8 knock-down cells. Cancer cells, control or with altered KLF8 expression were analyzed to assess mammosphere formation efficiency, CSCs frequency and expression of CSCs factors. Tumor growth in vivo of control or KLF8 knock-down cells was assessed by fat-pad injection of these cell in immunocompromised mice.

Results

Here, we show that KLF8 is required and sufficient for regulating CSC phenotypes and regulating transcription factors SOX2, NANOG, OCT4 and c-MYC. KLF8 levels are associated with chemoresistance in triple negative breast cancer patients and overexpression in breast cancer cells increased paclitaxel resistance. KLF8 and OGT co-regulate each other to form a feed-forward loop to promote CSCs phenotype and mammosphere formation of breast cancer cells.

Discussion

These results suggest a critical role of KLF8 and OGT in promoting CSCs and cancer progression, that may serve as potential targets for developing strategy to target CSCs specifically.

Impact of Treadmill Interval Running on the Appearance of Zinc Finger Protein FHL2 in Bone Marrow Cells in a Rat Model: A Pilot Study

Although the benefits of physical exercise to preserve bone quality are now widely recognized, the intimate mechanisms leading to the underlying cell responses still require further investigations. Interval training running, for instance, appears as a generator of impacts on the skeleton, and particularly on the progenitor cells located in the bone marrow. Therefore, if this kind of stimulus initiates bone cell proliferation and differentiation, the activation of a devoted signaling pathway by mechano-transduction seems likely. This study aimed at investigating the effects of an interval running program on the appearance of the zinc finger protein FHL2 in bone cells and their anatomical location. Twelve 5-week-old male Wistar rats were randomly allocated to one of the following groups (n = 6 per group): sedentary control (SED) or high-intensity interval running (EX, 8 consecutive weeks). FHL2 identification in bone cells was performed by immuno-histochemistry on serial sections of radii. We hypothesized that impacts generated by running could activate, in vivo, a specific signaling pathway, through an integrin-mediated mechano-transductive process, leading to the synthesis of FHL2 in bone marrow cells. Our data demonstrated the systematic appearance of FHL2 (% labeled cells: 7.5%, p < 0.001) in bone marrow obtained from EX rats, whereas no FHL2 was revealed in SED rats. These results suggest that the mechanical impacts generated during high-intensity interval running activate a signaling pathway involving nuclear FHL2, such as that also observed with dexamethasone administration. Consequently, interval running could be proposed as a non-pharmacological strategy to contribute to bone marrow cell osteogenic differentiation.

High level of FHL2 exacerbates the outcome of non-small cell lung cancer (NSCLC) patients and the malignant phenotype in NSCLC cells

Non-small cell lung cancer (NSCLC) is a malignant tumour with high mortality. FHL2 has been identified as a biomarker of lung cancer. This research explored the effects of FHL2 expression on NSCLC. NSCLC-associated data sets were collected from the assistant for clinical bioinformatics and TCGA databases respectively. The association between FHL2 and clinical characteristics, the prognostic significance of FHL2 and the influences of various variables on NSCLC were determined by Pearson's chi-squared test, the Kaplan-Meier curve and the Cox regression model respectively. FHL2 level was altered by cell transfection and was measured by qRT-PCR. Tumour xenograft formation was completed by inoculating sh-FHL2/pcDNA-FHL2 transfected cells into BALB/c nude mice. Protein expression was assessed by western blot. Cell apoptosis, proliferation and epithelial - mesenchymal transition (EMT) characteristics were evaluated employing TUNEL, BrdU⁺ and microscopic observation respectively. The expression of Ki67 and N-cadherin was assessed by immunohistochemistry. The results showed that FHL2 was highly expressed in NSCLC tissues. Patients with high FHL2 expression experienced lower overall survival probability. FHL2 knockdown promoted apoptosis, but inhibited EMT of A549 and NCI-H460 cells, which was verified by the increased ratios of cleaved caspase 9/caspase 9 and cleaved caspase 3/caspase 3, as well as augmented E-cadherin and reduced N-cadherin. In an in vivo assay FHL2 knockdown decreased tumour volume and weight, repressed EMT, but enhanced apoptosis. FHL2 upregulation showed the opposite effects of FHL2 knockdown. Furthermore, FHL2 upregulation facilitated cell proliferation both in in vitro and in vivo assays. These outcomes indicated that high level of FHL2 facilitated tumorigenesis, as well as the proliferation and EMT of NSCLC cells.

Expression and Prognosis Value of the KLF Family Members in Colorectal Cancer

Krüppel-like factors (KLFs) are some kind of transcriptional regulator that regulates a broad range of cellular functions and has been linked to the development of certain malignancies. KLF expression patterns and prognostic values in colorectal cancer (CRC) have, however, been investigated rarely. To investigate the differential expression, predictive value, and gene mutations of KLFs in CRC patients, we used various online analytic tools, including ONCOMINE, TCGA, cBioPortal, and the TIMER database. KLF2-6, KLF8-10, KLF12-15, and KLF17 mRNA expression levels were dramatically downregulated in CRC tissues, but KLF1, KLF7, and KLF16 mRNA expression levels were significantly elevated in CRC tissues. According to the findings of Cox regression analysis, upregulation of KLF3, KLF5, and KLF6 and downregulation of KLF15 were linked with a better prognosis in CRC. For functional enrichment, our findings revealed that KLF members are involved in a variety of cancer-related biological processes. In colon cancer and rectal cancer, KLFs were also shown to be associated with a variety of immune cells. The findings of this research reveal that KLF family members' mRNA expression levels are possible prognostic indicators for patients with CRC.

Targeting key proteins involved in transcriptional regulation for cancer therapy: Current strategies and future prospective

The key proteins involved in transcriptional regulation play convergent roles in cellular homeostasis, and their dysfunction mediates aberrant gene expressions that underline the hallmarks of tumorigenesis. As tumor progression is dependent on such abnormal regulation of transcription, it is important to discover novel chemical entities as antitumor drugs that target key tumor-associated proteins involved in transcriptional regulation. Despite most key proteins (especially transcription factors) involved in transcriptional regulation are historically recognized as undruggable targets, multiple targeting approaches at diverse levels of transcriptional regulation, such as epigenetic intervention, inhibition of DNA-binding of transcriptional factors, and inhibition of the protein-protein interactions (PPIs), have been established in preclinically or clinically studies. In addition, several new approaches have recently been described, such as targeting proteasomal degradation and eliciting synthetic lethality. This review will emphasize on accentuating these developing therapeutic approaches and provide a thorough conspectus of the drug development to target key proteins involved in transcriptional regulation and their impact on future oncotherapy.

KLF8 is activated by TGF-β1 via Smad2 and contributes to ovarian cancer progression

Krüppel-like factor 8 (KLF8) is a transcription factor expressed abnormally in various cancer types and promotes oncogenic transformation. However, the role of KLF8 in ovarian cancer (OC) progression remains unclear. This study reports that transforming growth factor-β1 (TGF-β1)/Smad2/KLF8 axis regulates epithelial-mesenchymal transition (EMT) and contributes to OC progression. We analyzed the KLF8 expression in OC cells and tissues, wherein a significant overexpression of KLF8 was observed. Increased KLF8 expressions were correlated with higher cell proliferation, EMT, migration, and invasion and conferred poor clinical outcomes in OC patients. Overexpressed KLF8 increases F-actin polymerization and induces cytoskeleton remodeling of OC cells. Furthermore, a dissection of the molecular mechanism defined that TGF-β1 triggers KLF8 through the Smad2 pathway and regulates EMT. Pharmacological and genetic inhibition of Smad2 followed by TGF-β1 treatment failed to activate KLF8 expression and induction of EMT. Using promoter-luciferase reporter assays, we defined that upon TGF-β1 activation, phosphorylated Smad2 binds and promotes the KLF8 promoter activity, and knockdown of Smad2 inhibits KLF8 promoter activation. Together, these results demonstrate that TGF-β1 activates KLF8 expression by the Smad2 pathway, and KLF8 contributes to OC progression and may serve as a potential therapeutic strategy for treating OC patients.

Systems Toxicology Approach for Assessing Developmental Neurotoxicity in Larval Zebrafish

Adverse outcomes that result from chemical toxicity are rarely caused by dysregulation of individual proteins; rather, they are often caused by system-level perturbations in networks of molecular events. To fully understand the mechanisms of toxicity, it is necessary to recognize the interactions of molecules, pathways, and biological processes within these networks. The developing brain is a prime example of an extremely complex network, which makes developmental neurotoxicity one of the most challenging areas in toxicology. We have developed a systems toxicology method that uses a computable biological network to represent molecular interactions in the developing brain of zebrafish larvae. The network is curated from scientific literature and describes interactions between biological processes, signaling pathways, and adverse outcomes associated with neurotoxicity. This allows us to identify important signaling hubs, pathway interactions, and emergent adverse outcomes, providing a more complete understanding of neurotoxicity. Here, we describe the construction of a zebrafish developmental neurotoxicity network and its validation by integration with publicly available neurotoxicity-related transcriptomic datasets. Our network analysis identified consistent regulation of tumor suppressors p53 and retinoblastoma 1 (Rb1) as well as the oncogene Krüppel-like factor (Klf8) in response to chemically induced developmental neurotoxicity. The developed network can be used to interpret transcriptomic data in a neurotoxicological context.

Inhibition of TMPRSS4 mediated epithelial-mesenchymal transition is critically involved in antimetastatic effect of melatonin in colorectal cancers

In the current study, the underlying anti-metastatic mechanism of melatonin contained in some edible plants was explored in association with transmembrane protease serine 4 (TMPRSS4) mediated metastasis and epithelial-mesenchymal transition (EMT) signaling in human HCT15 and SW620 colorectal cancer cells. Here, TMPRSS4 was highly expressed in HCT15, but was weakly expressed in SW620 cells. Melatonin exerted weak cytotoxicity, decreased invasion, adhesion, and migration, and attenuated the expression of TMPRSS4, cyclin E, pro-urokinase-type plasminogen activator (pro-uPA), p-signal transducer and activator of transcription 3 (p-STAT3), p-focal adhesion kinase (p-FAK), Snail and increased the expression of E-cadherin, p27, pp38 and p-Jun N-terminal kinases (p-JNK) in HCT15 cells. Conversely, overexpression of TMPRSS4 reduced the ability of melatonin to activate E-cadherin and reduce Snail. Furthermore, even in SW620 cells transfected with TMPRSS4-overexpression plasmid, melatonin effectively suppressed invasion and migration along with decreased expression of Snail, cyclin A, cyclin E, pro-uPA and p-FAK and increased expression of E-cadherin and p27. Overall, these findings provide evidence that melatonin suppresses metastasis in colon cancer cells via inhibition of TMPRSS4 mediated EMT.

The role of Krüppel-like factor 8 in cancer biology: Current research and its clinical relevance

Cancer is one of the leading causes of mortality worldwide, ranked second after heart disease. Despite recent advancements in diagnosis and treatment, there are still numerous problems associated with cancer progression, disease recurrence, and therapeutic resistance that are partially explored. Several studies have recently revealed that Krüppel-like factor 8 (KLF8) regulates transcription of genes linked with diverse biological processes, including proliferation, epithelial to mesenchymal transition (EMT), migration, invasion, and inflammation. KLF8 is expressed ubiquitously in mammalian cells, and its aberrant expression has been manifested with several cancer types. Earlier studies demonstrated the crucial role of KLF8 in DNA repair and resistance to apoptosis in numerous cancer types. Hence, studying the function of KLF8 from the perspective of cancer progression and therapy resistance would help develop a new therapeutic avenue. In this review, we summarize the clinical relevance of KLF8 expression in various malignancies, focusing on recent updates in EMT, cellular signaling, and cancer stem cells. We also address the contribution of KLF8 in development, DNA repair, chemoresistance, and its clinical utility as a predictive biomarker.

The Clinical Relevance and Function of Krüppel-Like Factor 16 in Breast Cancer

Background

Krüppel-like factor 16 (KLF16), a member of the KLF family, is involved in metabolism and regulation of the endocrine system and has emerging roles in tumor progression. However, the expression of KLF16 and its role in breast cancer are elusive.

Methods

We investigated the expression and prognostic value of KLFs in breast cancer using data acquired from the TCGA BRCA dataset and the Kaplan–Meier plotter dataset. The protein levels of KLF16 in breast specimens were detected by immunohistochemistry (IHC). KLF16 silencing using shRNAs was performed to explore the effects of KLF16 on breast cancer cell growth, migration, and invasion. The expression of EMT markers in cells manipulated for KLF16 expression was assessed by Western blotting.

Results

Using publicly available dataset and specimens from breast cancer patients, we found that the expression levels of KLF16 were significantly higher in tumor tissues and that high levels of KLF16 were associated with poor prognosis in breast cancer patients. Moreover, KLF16 expression levels had relation to several clinicopathological parameters of breast cancer, including the molecular subtype and histological grade. Importantly, knockdown of KLF16 dramatically suppressed cell proliferation both in vitro and in vivo. Also, KLF16 deletion impaired migration, and invasion in breast cancer cells, and suppressed epithelial–mesenchymal transition (EMT).

Conclusion

Our results suggest that KLF16 has important oncogenic functions in breast cancer and that the expression levels of KLF16 are associated with prognosis in breast cancer patients. Our findings also suggest that KLF16 is involved in proliferation, migration, and invasion in breast cancer cells. Thus, KLF16 might be a promising prognostic marker and a therapeutic target for breast cancer.

MicroRNA‑500a‑5p inhibits colorectal cancer cell invasion and epithelial‑mesenchymal transition

The development of malignant tumors is a series of complex processes, the majority of which have not been elucidated. The aim of the present study was to investigate the microRNAs (miRNAs/miR) that affect the migration and invasion abilities of CRC cells. Our previous reports have revealed that miR‑500a‑5p suppressed CRC cell growth and malignant transformation. The present study demonstrated that overexpression of miR‑500a‑5p reduced the expression of vimentin, while increasing the expression of E‑cadherin. Inhibition of miR‑500a‑5p resulted in spindle‑like morphological changes and reorganization of F‑actin in CRC cells. Furthermore, miR‑500a‑5p attenuated the transforming growth factor‑β signaling pathway in EMT. Additionally, emodin inhibited the miR‑500a‑5p inhibitor and suppressed the EMT process. In animal models of metastasis using nude mice, EMT and LoVo cell metastasis was modulated by miR‑500a‑5p. Therefore, the findings of the present study demonstrated that miR‑500a‑5p is associated with a positive therapeutic outcome in terms of invasion/migration of CRC cells and mesenchymal‑like cell changes.

Expression, location and biological effects of four and a half LIM domain protein 2 (FHL2) on granulosa cells in ovine

Previous studies have shown that four and a half LIM domain protein 2 (FHL2) plays an essential role in the regulation of follicular development in mammals. Although the FHL2 genes of human and mouse have been well characterized, the expression and location of FHL2 in ovary and the biological functions of FHL2 on granulosa cells (GCs) of ovine are still not clear. In this study, full-length complementary DNA (cDNA) of FHL2 from ovine follicular GCs was amplified by real-time PCR (RT-PCR). The expression and location of FHL2 in ovary and GCs of ovine were studied by immunohistochemistry and immunofluorescence, and the biological effects of FHL2 on the cell proliferation, cell apoptosis, cell cycles and expression level of related genes of ovine GCs were also explored by overexpression or knockdown of FHL2. The results indicated that FHL2 was expressed in ovine follicular GCs and the sequence of the FHL2 cDNA was consistent with that predicted in GenBank, which did not cause an amino acid change. According to the results, FHL2 was expressed in ovine ovary and mainly located in the cytoplasm and nucleus of GCs. In addition, overexpression of FHL2 significantly reduced the cell viability, promoted the cell apoptosis and decreased the percentage of G0/G1 and S phase cells. RT-PCR showed that overexpression of FHL2 significantly increased the mRNA expression level of Bax and decreased the expression of Bcl-2 and the Bcl-2/Bax mRNA ratio compared with the control group. Besides, the knockdown of FHL2 gene in ovine GCs significantly improved the cell viability, suppressed the cell apoptosis, decreased the mRNA expression level of Caspase-3 gene, increased the Bcl-2/Bax mRNA ratio and increased the percentage of S and G2/M phase cells. Our results suggest that FHL2 may play an important role in the biological functions of GCs in ovine.

Role of FHL2 in digestive system malignancies

FHL2 is a scaffold protein that regulates signal transduction and gene transcription, and it has typical structural features of FHL proteins. Each FHL protein contains four half-LIM domains, and different LIM domains can bind to different proteins, which can activate or inhibit the activities of transcription factors such as P53 and serum response factors, and then influences the development of tumors. Previous studies have found that FHL2 has a complex biological role in tumorigenesis, and may promote or suppress tumor development in different types of tumors. In this article, we review the role of FHL2 in digestive system malignancies.

KLF3 is a crucial regulator of metastasis by controlling STAT3 expression in lung cancer

Lung cancer is one of the most common causes of cancer‐related mortality worldwide, which is partially due to its metastasis. However, the mechanism underlying its metastasis remains elusive. In this study, we showed that a low Krüppel‐like factor 3 (KLF3) expression level is correlated with a poor prognosis and TNM stages in clinical patients with lung cancer and further demonstrated that KLF3 expression is downregulated in lung cancer tissues compared with adjacent normal samples. In addition, bioinformatics analysis results showed that KLF3 expression is related to lung cancer epithelial‐mesenchymal transition (EMT). In vitro and in vivo experiments also showed that KLF3 silencing promotes lung cancer EMT and enhances lung cancer metastasis. More importantly, bioinformatics analysis and in vitro experiments indicated that the role of KLF3 in lung cancer metastasis is dependent on the STAT3 signaling pathway. Overall, our data indicated the crucial function of KLF3 in lung cancer metastasis and suggested opportunities to improve the therapy of patients with lung cancer.

microRNA-32-5p targets KLF2 to promote gastric cancer by activating PI3K/AKT signaling pathway

Krüppel-like factor 2 (KLF2) is a member of the zinc finger family, which is considered a potential tumor suppressor gene due to its reduced expression in gastric cancer. MicroRNAs (miRNAs) are a class of short non-coding single-stranded RNAs that are closely related to the development of gastric cancer. The purpose of this study was to investigate the miRNAs that regulate KLF2 and explore its specific mechanism in gastric cancer. Bioinformatics software Targetscan identified that microRNA-32-5p (miRNA-32-5p) may bind to KLF2 mRNA to regulate its expression. In order to verify the regulatory effect of miRNA-32-5p on KLF2, the proliferation and migration assays were performed in both KLF2 overexpression and KLF2 knockdown gastric cancer cells. Dual-Luciferase reporter assay proved that KLF2 could bind to the PTEN promoter to induce its expression. Moreover, research on molecular mechanisms indicated that both miRNA-32-5p and shKLF2 downregulated the expression of PTEN and activated the PI3K/AKT signaling to promote the development of gastric cancer. Targeting miRNA-32-5p and KLF2 is expected to provide new sign and target for gastric cancer treatment.

The level of Krüppel-like factor 8 expression predicts prognosis and metastasis in various carcinomas

BACKGROUND AND OBJECTIVE

Krüppel-like factor 8 (KLF8), a transcription factor, belongs to the KLF8 family. Currently, studies have shown that KLF8 is highly expressed in some tumors. However, the prognostic value and metastasis of KLF8 in cancers remain unclear. For the first time, we conducted meta-analysis to explore the relationship between KLF8 expression with prognosis and metastasis in various carcinomas patients.

METHODS

Web of Science, PubMed, Embase, and Cochrane Library were systematically searched for eligible articles. Pooled hazard ratios (HRs) and their 95% confidence intervals (95% CIs) were calculated to evaluate the prognostic value and metastasis of KLF8 expression in human cancer patients.

RESULTS

The result revealed that highly expression level of KLF8 was significantly associated with poor overall survival (OS) (HR = 1.56, 95% CI: 1.26-1.87). Meanwhile, this significant correlation was also observed in subgroup analysis stratified by cancer types, source of HR, sample size, follow-up (months). In addition, highly expression of KLF8 was also closely associated with metastasis (HR = 1.37, 95% CI: 0.57-2.17) and tumor node metastasis stage (HR = 1.58, 95% CI: 0.90-2.25) in carcinomas.

CONCLUSION

In summary, our meta-analysis indicates that overexpression of KLF8 may be associated with poor prognosis and higher incidence of metastasis in various carcinomas, and KLF8 may be used as a prognostic and metastatic indicator in human cancers.

Regulation of Krüppel-like factor 8 by the NEDD4 E3 ubiquitin ligase

Krüppel-like factor 8 (KLF8) plays many important roles in various diseases, especially cancer. Previous studies have shown that KLF8 is regulated by ubiquitylation. The molecular mechanism underlying this posttranslational modification of KLF8, however, has not been investigated. Reported here is our identification of the neural precursor cell expressed, developmentally down-regulated 4 (NEDD4) as the E3 ubiquitin ligase for this modification. By co-immunoprecipitation and ubiquitylation assays, we determined that KLF8 interacts with NEDD4 and is ubiquitylated by NEDD4. By site-directed mutagenesis and pharmacological inhibition of MEK, we found that the ubiquitylation of KLF8 by NEDD4 depends upon the phosphorylation of KLF8 at serine 48 by ERK. Cycloheximide chase analysis, target gene promoter reporter assay and fluorescent staining indicated that NEDD4 plays a critical role in promoting the stability and transcriptional activity of KLF8 in the nucleus. Taken together, this work identified NEDD4 as a novel E3 ubiquitin ligase for KLF8 that provides insights into targeting the KLF8-NEDD4 axis to treat various types of cancer associated with overexpression of both proteins.

Targeting liver cancer stem cells for the treatment of hepatocellular carcinoma

Liver cancer is one of the most common malignant tumors and prognosis remains poor. It has been increasingly recognized that liver cancer stem cells (LCSCs) are responsible for the carcinogenesis, recurrence, metastasis and chemoresistance of hepatocellular carcinoma (HCC). Targeting LCSCs is promising to be a new direction for the treatment of HCC. Herein, we summarize the potentially therapeutic targets in LCSCs at the level of genes, molecules and cells, such as knockout of oncogenes or oncoproteins, restoring the silent tumor suppressor genes, inhibition of the transcription factors and regulation of noncoding RNAs (including microRNAs and long noncoding RNAs) in LCSCs at the genetic level; inhibition of markers and blockade of the key signaling pathways of LCSCs at the molecular level; and inhibiting autophagy and application of oncolytic adenoviruses in LCSCs at the cellular level. Moreover, we analyze the potential targets in LCSCs to eliminate chemoresistance of HCC. Thereinto, the suppression of autophagy and Nanog by chloroquine and shRNA respectively may be the most promising targeting approaches. These targets may provide novel therapeutic strategies for the treatment of HCC by targeting LCSCs.

Hydrodynamic shear stress promotes epithelial-mesenchymal transition by downregulating ERK and GSK3β activities

BACKGROUND

Epithelial-mesenchymal transition (EMT) occurs in the tumor microenvironment and presents an important mechanism of tumor cell intravasation, stemness acquisition, and metastasis. During metastasis, tumor cells enter the circulation to gain access to distant tissues, but how this fluid microenvironment influences cancer cell biology is poorly understood.

METHODS AND RESULTS

Here, we present both in vivo and in vitro evidence that EMT-like transition also occurs in circulating tumor cells (CTCs) as a result of hydrodynamic shear stress (+SS), which promotes conversion of CD24middle/CD44high/CD133middle/CXCR4low/ALDH1low primary patient epithelial tumor cells into specific high sphere-forming CD24low/CD44low/CD133high/CXCR4high/ALDH1high cancer stem-like cells (CSLCs) or tumor-initiating cells (TICs) with elevated tumor progression and metastasis capacity in vitro and in vivo. We demonstrate that conversion of CSLCs/TICs from epithelial tumor cells via +SS is dependent on reactive oxygen species (ROS)/nitric oxide (NO) generation, and suppression of extracellular signal-related kinase (ERK)/glycogen synthase kinase (GSK)3β, a mechanism similar to that operating in embryonic stem cells to prevent their differentiation while promoting self-renewal.

CONCLUSION

Fluid shear stress experienced during systemic circulation of human breast tumor cells can lead to specific acquisition of mesenchymal stem cell (MSC)-like potential that promotes EMT, mesenchymal-epithelial transition, and metastasis to distant organs. Our data revealed that biomechanical forces appeared to be important microenvironmental factors that not only drive hematopoietic development but also lead to acquisition of CSLCs/TIC potential in cancer metastasis. Our data highlight that +SS is a critical factor that promotes the conversion of CTCs into distinct TICs in blood circulation by endowing plasticity to these cells and by maintaining their self-renewal signaling pathways.

Krüppel-like factor 8 regulates VEGFA expression and angiogenesis in hepatocellular carcinoma

Tumor angiogenesis plays a critical role in hepatocellular carcinoma (HCC) development and progression, but its mechanism is unclear. Krüppel-like factor 8 (KLF8) is a transcription factor that plays an important role in HCC progression. Here, we investigated the role of KLF8 in angiogenesis in HCC and its possible mechanism. Immunohistochemistry, quantitative RT-PCR, western blotting, promoter reporter assays, chromatin immunoprecipitation (ChIP), and chicken chorioallantoic membrane (CAM) and nude mouse tumor models were used to show that the mRNA and protein expression levels of KLF8 and VEGFA are highly correlated in HCC tissue samples. The up-regulation of KLF8 increased VEGFA protein levels and induced VEGFA promoter activity by binding to the CACCC region of the VEGFA promoter. In addition, KLF8 regulated HIF-1α and Focal adhesion kinase (FAK) expression. The PI3K/AKT inhibitor LY294002 inhibited KLF8-induced VEGFA expression, whereas PI3K/AKT signaling pathway proteins, such as P-PDK1(Ser241) and P-AKT(Thr308), were decreased significantly. KLF8-overexpressing HCC cells had a higher potential for inducing angiogenesis. Thus, our results indicate that KLF8 may induce angiogenesis in HCC by binding to the CACCC region of the VEGFA promoter to induce VEGFA promoter activity and through FAK to activate PI3K/AKT signaling to regulate HIF-1α expression levels.

FHL2 interacts with iASPP and impacts the biological functions of leukemia cells

iASPP is an inhibitory member of apoptosis-stimulating proteins of p53 (ASPP) family, which inhibits p53-dependent apoptosis. iASPP was highly expressed in acute leukemia, inhibited leukemia cells apoptosis and promoted leukemogenesis. In order to clarify its mechanism, a yeast two-hybrid screen was performed and FHL2 was identified for the first time as one of the binding proteins of iASPP. FHL2 was highly expressed in K562 and Kasumi-1 cells. FHL2 and iASPP interacted with each other and co-localized in both nucleus and cytoplasm. Either FHL2 or iASPP silenced could reduce cell proliferation, induce cell cycle arrest at G0/G1 phase, and increase cell apoptosis. Western blot analysis showed that the level of p21 and p27 increased, CDK4, E2F1, Cyclin E and anti-apoptotic proteins Bcl-2 and Bcl-xL reduced. Interestingly, when FHL2 was knocked down, the protein expression level of iASPP also decreased. Similarly, the expression of FHL2 would reduce when iASPP was silenced. These results indicated that FHL2 might be a novel potential target for acute myelocytic leukemia treatment.

Oncogene FOXK1 enhances invasion of colorectal carcinoma by inducing epithelial-mesenchymal transition

Transcriptional factor FOXK1 is a member of the FOX family, involved in the cell growth and metabolism. The higher expression of FOXK1 leads to a variety of diseases and may play an important role in the development of various tumors. However, the role of FOXK1 in the progression of colorectal cancer (CRC) remains unknown. We demonstrated that FOXK1 was overexpressed in 16 types of solid tumor tissues via tissue multi-array (TMA). We found that FOXK1 induced elevated expressions and transactivities of five major oncogenes in CRC. Moreover, the elevated expression of FOXK1 was showed to be correlated with tumor progression and was a significant predictor of overall survival in CRC patients. Furthermore, it was showed that the depletion of FOXK1 expression could inhibit the migratory and invasive abilities of CRC cells. In contrast, ectopic expression of FOXK1 elicited the opposite effects on these phenotypes in vitro. FOXK1 promoted tumor metastasis through EMT program induction. In addition, TGF-β1 induced FOXK1 expression in a time-dependent pattern and the knockdown of FOXK1 inhibited TGF-β1-induced EMT. In vivo, higher expression of FOXK1 promotes CRC cell invasion and metastasis, and induces EMT in CRC as well. Alltogether, it was concluded that the higher expression of FOXK1 could indicate a poor prognosis in CRC patients since that FOXK1 induces EMT and promotes CRC cell invasion in vitro and in vivo.

MicroRNA-30a-5p (miR-30a) regulates cell motility and EMT by directly targeting oncogenic TM4SF1 in colorectal cancer

PURPOSE

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, and many oncogenes and tumor suppressor genes are involved in CRC. MicroRNAs (miRNAs) are small non-coding RNAs that can negatively regulate gene expression. Previous studies have revealed that miRNAs regulate the development and progression of many cancers. In this study, we investigated the role of microRNA-30a-5p (miR-30a) in CRC and its unknown mechanisms.

METHODS

qRT-PCR was used to detect miR-30a and TM4SF1 mRNA expression in CRC specimens and cell lines. CRC cell migration and invasion were assessed after transfection with miR-30a or TM4SF1 using wound healing and trans-well migration and invasion assays. Transmembrane-4-L-six-family protein (TM4SF1) was validated as a target of miR-30a in CRC through luciferase reporter assay and bioinformatics algorithms. Moreover, two EMT regulators, E-cadherin and VEGF, were also identified using Western blotting and immunohistochemistry.

RESULTS

We found that miR-30a was down-regulated in CRC tumor tissues and cell lines, and miR-30a was inversely associated with advanced stage and lymph node metastatic status compared with normal tissues. miR-30a decreased migration and invasion in CRC cell lines, and miR-30a overexpression not only down-regulated TM4SF1 mRNA and protein expression, but also inhibited the expression of VEGF and enhanced expression of E-cadherin. We also showed that TM4SF1 was up-regulated in CRC tumor specimens compared with adjacent normal tissues, and TM4SF1 expression was significantly associated with advanced stage and lymph node status compared with adjacent normal tissues.

CONCLUSIONS

These results suggest that miR-30a is an important regulator of TM4SF1, VEGF, and E-cadherin for CRC lymph node metastasis, a potential new therapeutic target in CRC.

Krüppel-like factor 8 induces epithelial-to-mesenchymal transition and promotes invasion of pancreatic cancer cells through transcriptional activation of four and a half LIM-only protein 2

Pancreatic cancer (PC) is one of the most aggressive types of cancer with an extremely poor prognosis. Invasive growth and early metastasis is one of the greatest challenges to overcome for the treatment of PC. Numerous previous studies have indicated that the transcription factor Krüppel-like factor 8 (KLF8) and nuclear cofactor four and a half LIM-only protein 2 (FHL2) serve important roles in tumorigenesis and tumor progression; however, their roles in PC remain elusive. The present study revealed that KLF8 and FHL2 expression is aberrantly co-overexpressed in PC tissue samples and associated with tumor metastasis. Furthermore, a positive correlation between the expression levels of KLF8 and FHL2 was observed. Subsequently, the present study identified KLF8 as a critical inducer of epithelial-to-mesenchymal transition (EMT) and invasion. Of note, the present study demonstrated that KLF8 overexpression induced a strong increase in FHL2 expression, and subsequent promoter reporter assays determined that KLF8 directly bound and activated the FHL2 gene promoter. Furthermore, FHL2 knockdown in KLF8-overexpressing cells partially reversed the EMT and invasive phenotypes. The present study identified KLF8-induced FHL2 activation as a novel and critical signaling mechanism underlying human PC invasion.

The cancer cell adhesion resistome: mechanisms, targeting and translational approaches

Cell adhesion-mediated resistance limits the success of cancer therapies and is a great obstacle to overcome in the clinic. Since the 1990s, where it became clear that adhesion of tumor cells to the extracellular matrix is an important mediator of therapy resistance, a lot of work has been conducted to understand the fundamental underlying mechanisms and two paradigms were deduced: cell adhesion-mediated radioresistance (CAM-RR) and cell adhesion-mediated drug resistance (CAM-DR). Preclinical work has evidently demonstrated that targeting of integrins, adapter proteins and associated kinases comprising the cell adhesion resistome is a promising strategy to sensitize cancer cells to both radiotherapy and chemotherapy. Moreover, the cell adhesion resistome fundamentally contributes to adaptation mechanisms induced by radiochemotherapy as well as molecular drugs to secure a balanced homeostasis of cancer cells for survival and growth. Intriguingly, this phenomenon provides a basis for synthetic lethal targeted therapies simultaneously administered to standard radiochemotherapy. In this review, we summarize current knowledge about the cell adhesion resistome and highlight targeting strategies to override CAM-RR and CAM-DR.

RUFY3 interaction with FOXK1 promotes invasion and metastasis in colorectal cancer

RUFY3 is highly expressed in brain tissue and has a role in neuronal development. Transcriptional factor FOXK1 is involved in cell growth and metabolism. We knew that RUFY3 or FOXK1 has been correlated with the malignant of tumor cells. However, the role of these molecules in colorectal cancer (CRC) progression remains unknown. We investigated the protein expression levels by Western blot, immunofluorescence and immunohistochemistry analyses. The migration and invasive abilities of CRC cells were assessed using shRNA-mediated inhibition in vitro and in vivo. We showed that RUFY3 expression was up-regulated in CRC compared with its expression in a normal human colon cell line (FHC). RUFY3 suppression inhibited anchorage independent cell tumorigenesis. RUFY3 induced elevated expression of eight major oncogenes. Moreover, RUFY3 physically interacts with FOXK1 in CRC. A positive correlation was observed between the expression patterns of RUFY3 and FOXK1. Furthermore, RUFY3 and FOXK1 expression were correlated with tumor progression and represented significant predictors of overall survival in CRC patients. SiRNA-mediated repression of FOXK1 in RUFY3-overexpressing cells reversed the epithelial-mesenchymal transition (EMT) and metastatic phenotypes. In vivo, FOXK1 promoted RUFY3-mediated metastasis via orthotopic implantation. These findings suggest that the RUFY3-FOXK1 axis might promote the development and progression of human CRC.

Overexpression of Srcin1 contributes to the growth and metastasis of colorectal cancer

The adaptor protein Srcin1 is a novel Src-binding protein that regulates Src activation through C-terminal Src kinase (Csk). Srcin1 behaves as a tumour suppressor in breast cancer, but the role of Srcin1 in the development of colorectal cancer (CRC) remains unknown. In the present study, Srcin1 expression in normal tissue was examined by tissue microarray and assessed by immunohistochemistry in 10 patients. In addition, the biological impact of Srcin1 knockdown on CRC cells was investigated in vitro and in vivo. The results showed that Srcin1 was expressed in different types of normal human tissues, whereas its expression was increased in human CRC tissues. Srcin1 expression also correlated with tumour progression. The suppression of Srcin1 induced cell differentiation and G0/G1 cell cycle arrest. Furthermore, Srcin1 increased cell growth as well as the capacity of migration and invasion in CRC cells. Srcin1 induced the activation of the Wnt/β-catenin signalling pathway. Moreover, Srcin1 suppression sensitized cancer cells to 5-fluorouracil (5-FU)-induced apoptosis in vitro and in vivo. Together, these results demonstrate that Srcin1 contributes to CRC carcinogenesis, invasion and metastasis. These findings provide a rationale for a mechanistic approach to CRC treatment based on the development of Srcin1-targeted therapies.

Rufy3 promotes metastasis through epithelial-mesenchymal transition in colorectal cancer

Rufy3 is a RUN domain-containing protein that has been associated with gastric cancers; however, the role of Rufy3 in the progression of colorectal cancer (CRC) remains unknown. We demonstrated that Rufy3 expression was higher in 11/12 fresh CRC tissues than in adjacent normal tissues. Rufy3 induced elevated expression and transactivity of four major oncogenes in CRC. Moreover, siRNA-mediated repression of Rufy3 induced G0/G1 cell cycle arrest, and Rufy3 overexpression enhanced CRC cell proliferation in vitro and in vivo. Furthermore, Rufy3 up-regulation promoted epithelial-mesenchymal transition (EMT) and metastatic phenotypes. Using an established in vitro cell model of 5-fluorouracil-resistant (5-FU) CRC cells, we assessed cellular morphology, molecular changes, and invasion and found that these characteristics were consistent with EMT. Silencing of Rufy3 by siRNA reversed EMT and greatly diminished the invasion of 5-FU-treated cells. In addition, TGF-β1 induced Rufy3 expression in a dose-dependent manner, and Rufy3 knockdown inhibited TGF-β1-induced EMT. In vivo, higher expression of Rufy3 promoted CRC cell invasion and metastasis and induced EMT. Taken together, this work identified that Rufy3 promoted cancer metastasis in CRC cells through EMT induction.

FOXK1 interaction with FHL2 promotes proliferation, invasion and metastasis in colorectal cancer

The transcriptional factor Forkhead box k1 (FOXK1) is a member of the FOX family. The abnormal expression of FOXK1 may have an important role in tumour development. Our previous studies showed that four-and-a-half LIM protein 2 (FHL2) is a critical inducer of the epithelial-to-mesenchymal transition (EMT) and invasion. However, the molecular mechanism by which FOXK1 synergizes with FHL2 tumour proliferation, EMT and metastasis is not well defined. We evaluated that messenger RNA (mRNA) and protein expression levels by quantitative RT–PCR, western blot, immunofluorescence and immunohistochemistry (IHC) assays. The migration and invasive abilities of colorectal cancer (CRC) cells were evaluated using short hairpin RNA (shRNA)-mediated inhibition in vitro and in vivo. We showed that FOXK1 expression was upregulated in CRC compared with matched normal tissues. FOXK1 physically interacts with FHL2 in CRC. Moreover, higher expression levels of the two proteins were significantly associated with differentiation, lymph node metastasis, AJCC stage and poorer prognosis. Furthermore, the overexpression of FOXK1 in CRC cells is associated with EMT, invasion and metastasis. However, the siRNA-mediated repression of FHL2 in FOXK1-overexpressing cells reversed EMT and both the proliferative and metastatic phenotypes in vitro and in vivo. These data identified that the co-expression of FOXK1 and FHL2 enhances cell proliferation and metastasis through the induction of EMT. Thus, FOXK1 and FHL2 may serve as putative targets in the combined therapy of CRC.

Direct regulation of FOXK1 by C-jun promotes proliferation, invasion and metastasis in gastric cancer cells

Forkhead box (FOX) K1 is a member of the FOX transcription factor superfamily. High FOXK1 expression is associated with several cancers. However, whether FOXK1 expression contributes to gastric cancer (GC) development and progression remains unknown. We analyzed the FOXK1 promoter using the Promo software and found several binding sequence transcription factors, including c-jun. However, the molecular mechanism by which FOXK1 affects the c-jun-mediated malignant phenotype is poorly understood. Here, we found that FOXK1 protein expression was higher in 8/10 (80.0%) fresh cancer tissues compared with that in adjacent normal tissues. FOXK1 overexpression enhanced the proliferation, migration and invasion of GC cells. Moreover, FOXK1 expression was stimulated by transforming growth factor-β1 (TGF-β1). FOXK1 acted as a potential epithelial-to-mesenchymal transition (EMT) inducer by stimulating vimentin expression and inducing the loss of E-cadherin in stable FOXK1-transfected cells. The results of promoter reporter and chromatin immunoprecipitation assays demonstrated that c-jun directly binds to and activates the human FOXK1 gene promoter. A positive correlation was observed between the expression patterns of FOXK1 and c-jun in GC cells and tissue. FOXK1 and c-jun expression were correlated with tumor progression and represented significant predictors of overall survival in GC patients. However, the siRNA-mediated repression of c-jun in FOXK1-overexpressing cells reversed EMT, as well as the proliferative and metastatic phenotypes. In vivo, c-jun promoted FOXK1-mediated proliferation and metastasis via orthotopic implantation. The evidence presented here suggests that FOXK1-directed regulation by c-jun promote the development and progression of human GC.

Single-cell RNA-seq reveals novel regulators of human embryonic stem cell differentiation to definitive endoderm

BACKGROUND

Human pluripotent stem cells offer the best available model to study the underlying cellular and molecular mechanisms of human embryonic lineage specification. However, it is not fully understood how individual stem cells exit the pluripotent state and transition towards their respective progenitor states.

RESULTS

Here, we analyze the transcriptomes of human embryonic stem cell-derived lineage-specific progenitors by single-cell RNA-sequencing (scRNA-seq). We identify a definitive endoderm (DE) transcriptomic signature that leads us to pinpoint a critical time window when DE differentiation is enhanced by hypoxia. The molecular mechanisms governing the emergence of DE are further examined by time course scRNA-seq experiments, employing two new statistical tools to identify stage-specific genes over time (SCPattern) and to reconstruct the differentiation trajectory from the pluripotent state through mesendoderm to DE (Wave-Crest). Importantly, presumptive DE cells can be detected during the transitory phase from Brachyury (T) (+) mesendoderm toward a CXCR4 (+) DE state. Novel regulators are identified within this time window and are functionally validated on a screening platform with a T-2A-EGFP knock-in reporter engineered by CRISPR/Cas9. Through loss-of-function and gain-of-function experiments, we demonstrate that KLF8 plays a pivotal role modulating mesendoderm to DE differentiation.

CONCLUSIONS

We report the analysis of 1776 cells by scRNA-seq covering distinct human embryonic stem cell-derived progenitor states. By reconstructing a differentiation trajectory at single-cell resolution, novel regulators of the mesendoderm transition to DE are elucidated and validated. Our strategy of combining single-cell analysis and genetic approaches can be applied to uncover novel regulators governing cell fate decisions in a variety of systems.

Krüppel-like factor 8 promotes cancer stem cell-like traits in hepatocellular carcinoma through Wnt/β-catenin signaling

Krüppel-like factor 8 (KLF8) is highly expressed in hepatocellular carcinoma (HCC) and contributes to tumor initiation and progression by promoting HCC cell proliferation and invasion. However, the role of KLF8 in liver cancer stem cells (LCSCs) is not known. In the current study, we investigated the role of KLF8 in LCSCs to determine if KLF8 is a novel marker of these cells. We found that KLF8 was highly expressed in primary HCC tumors, distant migrated tissues, and LCSCs. Patients with high KLF8 expression had a poor prognosis. KLF8 promoted stem cell-like features through activation of the Wnt/β-catenin signaling pathway. Cell apoptosis was significantly increased in HCC cells with knockdown of KLF8 compared with the control cells when treated with the same doses of sorafenib or cisplatin. Taken together, our study shows that KLF8 plays a potent oncogenic role in HCC tumorigenesis by maintaining stem cell-like features through activation of the Wnt/β-catenin signaling pathway and promoting chemoresistance. Thus, targeting KLF8 may provide an effective therapeutic approach to suppress tumorigenicity of HCC. © 2016 Wiley Periodicals, Inc.

ERK2 phosphorylates Krüppel-like factor 8 protein at serine 48 to maintain its stability

Krüppel-like factor 8 (KLF8) plays important roles in cancer and is strictly regulated by various post-translational modifications such as sumoylation, acetylation, ubiquitylation and PARylation. Here we report a novel phosphorylation of KLF8 by ERK2 responsible and critical for the stability of KLF8 protein. The full-length KLF8 protein displays a doublet in SDS-PAGE gel. The upper band of the doublet, however, disappeared when the N-terminal 50 amino acids were deleted. In its full-length the upper band disappeared upon phosphatase treatment or mutation of the serine 48 (S48) to alanine whereas the lower band was lost when the S48 was mutated to aspartic acid that mimics phosphorylated S48. These results suggest that S48 phosphorylation is responsible for the motility up-shift of KLF8 protein. Pharmacological and genetic manipulations of various potential kinases identified ERK2 as the likely one that phosphorylates KLF8 at S48. Functional studies indicated that this phosphorylation is crucial for protecting KLF8 protein from degradation in the nucleus and promoting cell migration. Taken together, this study identifies a novel mechanism of phosphorylation critical for KLF8 protein stabilization and function.

MiR-381 functions as a tumor suppressor in colorectal cancer by targeting Twist1

MiR-381 has been reported to be dysregulated in several human cancers. However, the function and mechanism of miR-381 in colorectal cancer (CRC) remains unclear. In the present study, the miR-381 expression was assessed in a cohort of 113 CRC specimens using real-time quantitative polymerase chain reaction (RTq-PCR), which demonstrated that miR-381 was significantly downregulated in CRC and correlated with distant metastasis and tumor, node, and metastasis (TNM) stage. Functional study revealed that restoration of miR-381 significantly inhibited the invasion, migration, and epithelial–mesenchymal transition (EMT) of CRC cells. Luciferase reporter assay validated that Twist1, an important EMT inducer, was a direct target of miR-381, and rescued Twist1 attenuated the function of miR-381 in CRC cells. Correlation analysis also revealed an inverse correlation between miR-381 and Twist1 expression levels in CRC specimens. Taken together, our results highlight the significance of miR-381/Twist1 interaction in the development and progression of CRC, and suggest that restoration of miR-381 may be a potential therapeutic strategy for the patients with CRC.