Up-regulation of Krüppel-like factor 8 promotes tumor invasion and indicates poor prognosis for hepatocellular carcinoma

A novel biomarker associated with EBV infection improves response prediction of immunotherapy in gastric cancer

BACKGROUND

Novel biomarkers are required in gastric cancer (GC) treated by immunotherapy. Epstein-Barr virus (EBV) infection induces an immune-active tumor microenvironment, while its association with immunotherapy response is still controversial. Genes underlying EBV infection may determine the response heterogeneity of EBV + GC. Thus, we screened hub genes associated with EBV infection to predict the response to immunotherapy in GC.

METHODS

Prognostic hub genes associated with EBV infection were screened using multi-omic data of GC. EBV + GC cells were established and confirmed by EBV-encoded small RNA in situ hybridization (EBER-ISH). Immunohistochemistry (IHC) staining of the hub genes was conducted in GC samples with EBER-ISH assay. Infiltrating immune cells were stained using immunofluorescence.

RESULTS

CHAF1A was identified as a hub gene in EBV + GC, and its expression was an independent predictor of overall survival (OS). EBV infection up-regulated CHAF1A expression which also predicted EBV infection well. CHAF1A expression also predicted microsatellite instability (MSI) and a high tumor mutation burden (TMB). The combined score (CS) of CHAF1A expression with MSI or TMB further improved prognostic stratification. CHAF1A IHC score positively correlated with the infiltration of NK cells and macrophages M1. CHAF1A expression alone could predict the immunotherapy response, but its CS with EBV infection, MSI, TMB, or PD-L1 expression showed better effects and improved response stratification based on current biomarkers.

CONCLUSIONS

CHAF1A could be a novel biomarker for immunotherapy of GC, with the potential to improve the efficacy of existing biomarkers.

An oncogene regulating chromatin favors response to immunotherapy: Oncogene CHAF1A and immunotherapy outcomes

Many biological processes related to cell function and fate begin with chromatin alterations, and many factors associated with the efficacy of immune checkpoint inhibitors (ICIs) are actually downstream events of chromatin alterations, such as genome changes, neoantigen production, and immune checkpoint expression. However, the influence of genes as chromatin regulators on the efficacy of ICIs remains elusive, especially in gastric cancer (GC). In this study, thirty out of 1593 genes regulating chromatin associated with a favorable prognosis were selected for GC. CHAF1A, a well-defined oncogene, was identified as the highest linkage hub gene. High CHAF1A expression were associated with microsatellite instability (MSI), high tumor mutation burden (TMB), high tumor neoantigen burden (TNB), high expressions of PD-L1 and immune effector genes, and live infiltration of immune cells. High CHAF1A expression indicated a favorable response and prognosis in immunotherapy of several cohorts, which was independent of MSI, TMB, TNB, PD-L1 expression, immune phenotype and transcriptome scoring, and improved patient selection based on these classic biomarkers. In vivo, CHAF1A knockdown alone inhibited tumor growth but it impaired the effect of an anti-PD-1 antibody by increasing the relative tumor proliferation rate and decreasing the survival benefit, potentially through the activation of TGF-β signaling. In conclusion, CHAF1A may be a novel biomarker for improving patient selection in immunotherapy.

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.

The Role of BTBD7 in Normal Development and Tumor Progression

BTB/POZ domain-containing protein 7 (BTBD7) has a relative molecular weight of 126KD and contains two conserved BTB/POZ protein sequences. BTBD7 has been shown to play an essential role in normal human development, precancerous lesions, heat-stress response, and tumor progression. BTBD7 promotes branching morphogenesis during development and participates in the salivary gland, lung, and tooth formation. Furthermore, many studies have shown that aberrant expression of BTBD7 promotes heat stress response and the progression of precancerous lesions. BTBD7 has also been found to play an important role in cancer. High expression of BTBD7 affects tumor progression by regulating multiple pathways. Therefore, a complete understanding of BTBD7 is crucial for exploring human development and tumor progression. This paper reviews the research progress of BTBD7, which lays a foundation for the application of BTBD7 in regenerative medicine and as a biomarker for tumor prediction or potential therapeutic target.

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.

PELI1 promotes radiotherapy sensitivity by inhibiting noncanonical NF-κB in esophageal squamous cancer

The low sensitivity of radiotherapy is the main cause of tumor tolerance against ionizing radiation (IR). However, the molecular mechanisms by which radiosensitivity is controlled remain elusive. Here, we observed that high expression of pellino E3 ubiquitin protein ligase 1 (PELI1) was correlated with improved prognosis in human esophageal squamous cell carcinoma stage III patients that received adjuvant radiotherapy. Moreover, we found PELI1‐mediated IR‐induced tumor cell apoptosis in vivo and in vitro. Mechanistically, PELI1 mediated the lysine 48 (Lys48)–linked polyubiquitination and degradation of NF‐κB–inducing kinase (NIK; also known as MAP3K14), the master kinase of the noncanonical NF‐κB pathway, thereby inhibiting IR‐induced activation of the noncanonical NF‐κB signaling pathway during radiotherapy. As a consequence, PELI1 inhibited the noncanonical NF‐κB–induced expression of the anti‐apoptotic gene BCL2 like 1 (Bclxl; also known as BCL2L1), leading to an enhancement of the IR‐induced apoptosis signaling pathway and ultimately promoting IR‐induced apoptosis in tumor cells. Therefore, Bclxl or NIK knockdown abolished the apoptosis‐resistant effect in PELI1‐knockdown tumor cells after radiotherapy. These findings establish PELI1 as a critical tumor intrinsic regulator in controlling the sensitivity of tumor cells to radiotherapy through modulating IR‐induced noncanonical NF‐κB expression.

Circulating Tumor Cells Expressing Krüppel-Like Factor 8 and Vimentin as Predictors of Poor Prognosis in Pancreatic Cancer Patients

BACKGROUND

Circulating tumor cells (CTCs) with an epithelial-mesenchymal transition phenotype in peripheral blood may be a useful marker of carcinomas with poor prognosis. The aim of this study was to determine the prognostic significance of CTCs expressing Krüppel-like factor 8 (KLF8) and vimentin in pancreatic cancer (PC).

METHODS

CTCs were isolated by immunomagnetic separation from the peripheral blood of 40 PC patients before undergoing surgical resection. Immunocytochemistry was performed to identify KLF8⁺ and vimentin⁺ CTCs. The associations between CTCs and time to recurrence (TTR), clinicopathologic factors, and survival were assessed. Univariate and multivariate analyzes were performed to identify risk factors.

RESULTS

Patients with CTCs (n = 30) had a higher relapse rate compared to those without (n = 10) (70.0% vs 20.0%; P < 0.01). The proportion of KLF8⁺/vimentin⁺ CTCs to total CTCs was inversely related to TTR (r = -0.646; P < 0.01); TTR was reduced in patients with > 50% of CTCs identified as KLF8⁺/vimentin⁺ (P < 0.01). Independent risk factors for recurrence were perineural invasion and > 50% KLF8⁺/vimentin⁺ CTCs (both P < 0.05).

CONCLUSION

Poor prognosis can be predicted in PC patients when > 50% of CTCs are positive for KLF8 and vimentin.

ASRGL1 Correlates With Immune Cell Infiltration in Hepatocellular Carcinoma and Can Serve as a Prognostic Biomarker

Background

The enzyme L-asparaginase (ASRGL1) catalyzes the hydrolysis of L-asparagine (Asn) to L-aspartic acid (Asp) and ammonia. Numerous studies have shown a strong correlation between ASRGL1 expression and tumorigenesis. However, the expression and biological function of ASRGL1 in hepatocellular carcinoma (HCC) are still unclear.

Methods

We explored the mRNA expression of ASRGL1 in HCC using the HCCDB, Oncomine, and TIMER 2.0 databases. Western blotting and immunohistochemical analyses were also used to determine the mRNA expression of ASRGL1 in HCC. LinkedOmics was used to analyze the genes co-expressed with ASRGL1 and regulators including kinases, miRNAs, and transcription factors. The Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the co-expressed genes were also investigated using LinkedOmics. The correlation between ASRGL1 expression and immune infiltrates was analyzed using the TIMER 2.0 and Gene Expression Profiling Interactive Analysis (GEPIA) databases. The effects of ASRGL1 expression on patient outcome were investigated using the UALCAN and GEPIA databases, and the Kaplan–Meier plotter. c-Bioportal was used to explore the mutations of ASRGL1 in HCC.

Results

Compared with the adjacent tissues, ASRGL1 was upregulated in HCC. High ASRGL1 expression in HCC indicated poor relapse-free survival, progression-free survival, disease-specific survival, and overall survival. The expression of ASRGL1 was significantly correlated with infiltrating levels of B cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells in HCC.

Conclusion

Our findings suggest that ASRGL1 is overexpressed in HCC and that ASRGL1 expression was significantly correlated with immune infiltration in HCC and prognosis. Therefore, ASRGL1 may serve as a biomarker for the early diagnosis and treatment of HCC.

Krüppel-like factor 12 suppresses bladder cancer growth through transcriptionally inhibition of enolase 2

Krüppel-like factors (KLFs) are transcription factors and play important roles in bladder cancer (BC). Clarifying the function of KLFs will provide new strategies for clinical treatment of BC. In this study, we found that Krüppel-like factor 12 (KLF12) was decreased in BC tissues and cells. Knockdown of KLF12 by siRNA dramatically elevated the proliferation and colony formation of BC cells. By contrast, overexpressing KLF12 suppressed the cell viability and the number of clones. Overexpression of KLF12 also regulated cell cycle progression, apoptosis and migration of BC cells. Furthermore, KLF12 bound to the promoter of enolase 2 (ENO2) and transcriptionally inhibited the expression of ENO2, which was highly expressed in BC tissues. KLF12 suppressed, while ENO2 promoted glycolysis. Lastly, ENO2 overexpression and knockdown promoted and suppressed the proliferation and migration of BC cells, respectively. These results suggest that KLF12 acts as a tumor suppressor by negatively regulated ENO2. Targeting ENO2 is a promising treatment strategy for this malignancy.

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.

A novel role of Krüppel-like factor 8 as an apoptosis repressor in hepatocellular carcinoma

Background

Krüppel-like factor 8 (KLF8), a cancer-promoting factor that regulates critical gene transcription and cellular cancer-related events, has been implicated in tumor development and progression. However, the functional role of KLF8 in the pathogenesis of hepatocellular carcinoma (HCC) remains largely unknown.

Methods

The gene expression patterns and genome-wide regulatory profiles of HCC cells after KLF8 knockout were analyzed by using RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) of histone H3 lysine 27 acetylation (H3K27ac) combined with bioinformatics analysis. Transcription factor-binding motifs that recognized by KLF8 were evaluated by motif analysis. For the predicted target genes, transcriptional changes were examined by ChIP, and loss of function experiments were conducted by siRNA transfection.

Results

KLF8 functioned as a transcription repressor in HCC and mainly regulated apoptotic-related genes directly. A total of 1,816 differentially expressed genes after KLF8 knockout were identified and significantly corresponded to global changes in H3K27ac status. Furthermore, two predicted target genes, high-mobility group AT-hook 2 (HMGA2) and matrix metalloproteinase 7 (MMP7), were identified as important participants in KLF8-mediated anti-apoptotic effect in HCC. Knockout of KLF8 enhanced cell apoptosis process and caused increase in the associated H3K27ac, whereas suppression HMGA2 or MMP7 attenuated these biological effects.

Conclusions

Our work suggests a novel role and mechanism for KLF8 in the regulation of cell apoptosis in HCC and facilitates the discovery of potential therapeutic targets for HCC treatment.

A polymorphism within the mismatch repair gene predicts prognosis and adjuvant chemotherapy benefit in gastric cancer

BACKGROUND

Defective mismatch repair (dMMR) and microsatellite instability (MSI) correlate with gastric cancer (GC) outcome. We hypothesized that MMR genetic polymorphisms that have low-penetrant effects but may cause heterogeneous MMR capability among individuals also affect GC outcome.

METHODS

The polymorphisms rs1800734 in MLH1, rs2303428 and rs3732183 in MSH2, rs735943 in EXO1, and rs11797 in TREX1 were selected and analyzed in independent discovery and validation sets that included 167 and 593 patients, respectively. MSI was determined.

RESULTS

In both the discovery and validation sets, the rs2303428 TC + CC genotype correlated with poor overall survival (OS) in non-cardia (P < 0.05) but not in cardia GC. Multivariate models showed that for OS of patients with non-cardia GC, the rs2303428 TC + CC genotype was an independent predictor in the validation set (HR 1.54; 95% CI 1.02-2.32; P = 0.040) and had a trend to be an independent predictor in the discovery set (HR 1.70; 95% CI 0.96-3.01; P = 0.067). Furthermore, in both patient sets, fluoropyrimidines-based adjuvant chemotherapy improved OS for non-cardia patients with the rs2303428 TC + CC genotype (HR 0.14; 95% CI 0.04-0.57; P = 0.006; and HR 0.29; 95% CI 0.15-0.58; P < 0.001, respectively) but not for those with the TT genotype. The rs2303428 genotypes were not associated with MSI frequency. The rs2303428 TC + CC genotype correlated with reduced expressions for thymidylate synthetase, P-glycoprotein and ERCC1 (P < 0.05) in non-cardia GC.

CONCLUSIONS

The rs2303428 genotypes may predict prognosis and adjuvant chemotherapy benefit in non-cardia GC patients.

KLF8 overexpression promotes the growth of human lung cancer cells by promoting the expression of JMJD2A

Background

Non-small-cell lung cancer (lung cancer) has become one of the leading causes worldwide and the underlying mechanism is not fully understood. The transcriptional factor Kruppel like factor 8 (KLF8) is involved in the initiation, progression, transformation, and metastasis of diverse cancers. However, the roles of KLF8 in human non-small cell lung cancer remain unknown.

Methods

CCK-8 kit and colony formation assay were performed to determine the cell growth of lung cancer cells. Flow cytometry analysis was used to evaluate apoptosis and cell cycle of lung cancer cells. Luciferase reporter assay was used to examine the activation of JMJD2A promoter by KLF8. Chromatin immunoprecipitation assay was performed to evaluate the binding of KLF8 to JMJD2A promoter. Western blot and polymerase chain reaction were applied to analyze the expression of interested genes.

Results

The mRNA and protein levels of KLF8 in human non-small cell lung cancer tissues were overexpressed compared with the non-cancer tissues. KLF8 was knocked down with lentivirus-mediated short-hairpin RNA (shRNA) in human lung cancer cells (A549 and H1299 cells). The phenotypic results showed that KLF8 knockdown decreased the proliferation rate and colony formation of lung cancer cells. By contrast, lentivirus-mediated KLF8 overexpression promoted the growth of lung cancer cells (A549 and H1299 cells) and non-cancerous bronchial epithelial cell line BEAS-2B. Next, we showed that KLF8 regulated cell cycle at the G0 phase but not regulates cellular apoptosis of lung cancer cells. KLF8 regulated the expression of the cell cycle regulators P21 and CDK4 in a JMJD2A-dependent manner and JMJD2A knockdown significantly blocked the functions of KLF8 in regulating cell cycle and proliferation of lung cancer cells. Finally, we observed that KLF8 bound the promoter of JMJD2A and facilitated the expression of JMJD2A.

Conclusions

Our evidence demonstrated that KLF8 upregulation in human lung cancer promotes the cell proliferation and colony formation of lung cancer cells. KLF8 binds to the promoter of JMJD2A and subsequently regulates the expression of P21 and CDK4, which contributes to the regulation of cell cycle by KLF8. KLF8 may serve as a target for the treatment of human lung cancer.

BMP2 secretion from hepatocellular carcinoma cell HepG2 enhances angiogenesis and tumor growth in endothelial cells via activation of the MAPK/p38 signaling pathway

Background

Hepatocellular carcinoma (HCC) is one of the most common tumors globally, with varying prevalence based on endemic risk factors. Bone morphogenetic protein (BMP) exhibits a broad spectrum of biological activities in various tissues including angiogenesis. Here, this study aimed to investigate the mechanism of BMP2 in HCC by mediating the mitogen-activated protein kinase (MAPK)/p38 signaling pathway.

Methods

BMP2 expression was quantified in HCC and adjacent tissues. BMP2 gain- and loss-of-function experiments were conducted by infection with lentivirus over-expressing BMP2 or expressing shRNA against BMP2. The angiogenesis was evaluated with HepG2 cells co-cultured with ECV304 cells. SB-239063 was applied to inhibit the activation of the MAPK/p38 signaling pathway so as to identify the significance of this pathway in HCC progression. Finally, in vivo experiments were conducted to identify the role of BMP2 and the MAPK/p38 signaling pathway in tumor growth and angiogenesis.

Results

BMP2 was highly expressed in HCC. Over-expression of BMP2 was found to accelerate cell proliferation, migration, invasion, microvascular density, and angiogenesis and decrease cell apoptosis in vitro and in vivo. BMP2 silencing exhibited inhibitory effects on HCC cell invasion and angiogenesis. The co-culture system illustrated that HepG2 cells secreted BMP2 in ECV304, and silenced BMP2 in HepG2 cells resulted in the inactivation of the MAPK/p38 signaling pathway, thus suppressing cancer progression, tumor growth, and angiogenesis in HCC.

Conclusion

Taken together, the key findings of this study propose that silencing of BMP2 inhibits angiogenesis and tumor growth in HCC, highlighting BMP2 silencing as a potential strategy for the treatment of HCC.

Histone chaperone CHAF1A impacts the outcome of fluoropyrimidines-based adjuvant therapy in gastric cancer by regulating the expression of thymidylate synthetase

BACKGROUND

Outcome in adjuvant chemotherapy of gastric cancer (GC) has considerable stage-independent variability, which underscores the need for prognostic or predictive molecular markers. CHAF1A promotes tumor growth while its impact on chemotherapy outcome remains unknown.

METHODS

CHAF1A protein expression was measured in independent discovery and validation sets that included 86 and 325 patients respectively who received fluoropyrimidines-based adjuvant chemotherapy after radical gastrectomy. The chemosensitizing effect of CHAF1A knockdown was investigated in vitro. Bioinformatics analysis based on RNA-seq and proteome data from public database was performed to investigate the potential mechanisms and further validation was conducted.

RESULTS

In both the discovery and validation sets, CHAF1A expression level was an independent predictor for disease-free survival (HR = 4.25; 95% CI: 2.31-7.79; P < 0.001; and HR = 1.91; 95% CI: 1.03-3.54; P = 0.039, respectively) and overall survival (HR = 3.25; 95% CI: 1.75-6.05; P < 0.001; and HR = 2.42; 95% CI: 1.12-5.20; P = 0.024, respectively) in patients with non-cardia GC but not in those with cardia GC. In GC cells, CHAF1A knockdown significantly decreased the IC₅₀ of 5-FU. Bioinformatics analyses indicated that CHAF1A correlated with folate metabolism and the expression of thymidylate synthetase (TS). Furthermore, CHAF1A knockdown significantly reduced TS expression in GC cells and CHAF1A positively correlated with TS protein expression in tumor tissues. Finally, ten proteins potentially relevant to the regulation of TS expression by CHAF1A were identified using online tools based on RNA-seq and proteome data.

CONCLUSIONS

CHAF1A may impact adjuvant chemotherapy outcome of GC by regulating the expression of TS.

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.

miRNA-448 inhibits cell growth by targeting BCL-2 in hepatocellular carcinoma

BACKGROUND

Increasing evidence indicates that aberrant micro (mi)RNA-448 expression plays a critical role in the progression of several human cancers. However, the function of miRNA-448 in hepatocellular carcinoma (HCC) has not been fully investigated.

METHODS

miRNA-448 expression levels in HCC tissues, adjacent non-cancerous tissues (ANTs), and HCC cell lines were examined by quantitative real-time polymerase chain reaction (qRT-PCR). HCC cells were treated with a miRNA-448 mimic or inhibitor, followed by cell viability measurements with the CCK-8 assay. Venn diagram analysis predicted, and dual luciferase reporter assays verified, the target gene of miRNA-448. Expression of the target gene was detected by qRT-PCR and immunohistochemistry. Growth of miRNA-448- or target gene-expressing HCC xenograft tumors in nude mice was measured.

RESULTS

miRNA-448 was expressed at a lower level in HCC tissues than ANTs, and correlated with a larger tumor size, incomplete tumor encapsulation, and advanced Barcelona Clinic Liver Cancer stage. miRNA-448 inhibited HCC cell growth. The downstream target of miRNA-448 was BCL-2, which was highly expressed in HCC tissues and its mRNA level was negatively correlated with miRNA-448 expression. In vivo, BCL-2 attenuated the tumor inhibiting effect of miRNA-448.

CONCLUSION

miRNA-448 functions as a tumor suppressor by targeting BCL-2 in HCC.

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.

Upregulation of liver kinase B1 predicts poor prognosis in hepatocellular carcinoma

The majority of studies report that liver kinase B1 (LKB1) acts as a tumor suppressor by inhibiting cell proliferation and metastasis. The present study investigated the expression pattern of LKB1 in 2 cohorts of paired hepatocellular carcinoma (HCC) and analogous non-cancerous tissues (ANT). The results indicated that LKB1 was upregulated in HCC vs. ANT tissues, and that high expression of LKB1 was associated with a higher number of tumor foci, larger tumor size, poorer tumor differentiation, Edmondson-Steiner grade, Barcelona Clinic Liver Cancer grade and tumor-node-metastasis stage. Furthermore, high LKB1 expression was associated with poor overall survival (OS), shorter disease-free survival and early recurrence. Univariate and multivariate analyses demonstrated that high LKB1 expression may serve as an independent prognostic marker for OS, but not for recurrence. In addition, knockdown of LKB1 expression in HCC cell lines inhibited cell proliferation and subcutaneous tumor growth by promoting cell apoptosis. Therefore, the findings of the present study suggest a protooncogenic role of LKB1 in HCC.

HOXB7 promotes tumor progression via bFGF-induced activation of MAPK/ERK pathway and indicated poor prognosis in hepatocellular carcinoma

The homeobox-containing gene HOXB7 plays an important role in the pathogenesis and progression of many cancers, yet its role in hepatocellular carcinoma (HCC) remains unclear. This study comprehensively analyzed the expression and clinical significance of HOXB7 in HCC and explored its potential mechanism in tumor progression. We found HOXB7 was highly expressed in HCC cell lines with highly metastatic potential and cancerous tissues from patients with tumor recurrence. The abilities of proliferation, migration, and invasion were notably decreased by depletion of HOXB7, and were enhanced by its enforced expression in vitro. HOXB7 expression was positively correlated with tumor progression and lung metastasis in vivo. The gene microarray data implied that HOXB7 affects biological functions of HCC cells through MAPK/ERK pathway activation. Further study confirmed that the effect of HOXB7 in activating MAPK/ERK pathway via induction of basic fibroblast growth factor (bFGF) secretion, and the inhibition of bFGF secretion could abolish MAPK/ERK pathway activation after ectopic expression of HOXB7. Chromatin immunoprecipitation experiments and luciferase reporter assays confirmed that HOXB7 promoted bFGF secretion via binding its promoter directly. Furthermore, the clinical significance of HOXB7 expression was confirmed using tissue microarrays containing 394 HCC tissue specimens. Patients with high HOXB7 expression showed shorter survival times and higher recurrence rates, and HOXB7 was an independent indicator for survival and recurrence. Overall, HOXB7 promotes HCC cell proliferation, migration, and invasion through the bFGF-induced MAPK/ERK pathway activation. It might be a novel prognostic factor in HCC and a promising therapeutic target for tumor metastasis and recurrence.

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.

MCM6 promotes metastasis of hepatocellular carcinoma via MEK/ERK pathway and serves as a novel serum biomarker for early recurrence

Background

The high incidence of recurrence and metastasis of hepatocellular carcinoma (HCC) necessitate the discovery of new predictive biomarkers of invasion and prognosis. Minichromosome maintenance complex component 6 (MCM6), which has been reported to up-regulate in multiple malignancies, was considered to be a novel diagnoses biomarker in HCC. However, its functional contributions and prognostic value remain unclear.

Methods

The expression of MCM6 was analyzed in 70 HCC tissues and 5 HCC cell lines by immunohistochemistry and real-time RT-PCR. The roles of MCM6 in HCC cell proliferation, migration and invasion were explored by CCK8, Wound healing and Transwell assays, respectively. Western blotting and Immunofluorescence staining were conducted to detect the protein expressions of ERK signaling pathway and EMT-related markers. To verify the above findings in vivo, we established subcutaneous xenograft tumor and orthotopic xenograft tumor models in nude mice. Finally, Enzyme-linked immunosorbent assay was used to evaluate the serum MCM6 level.

Results

MCM6 was significantly up-regulated in HCC tissues. Increased MCM6 expression was associated with aggressive clinicopathological features and worse prognosis in HCC patients. These results were consistent with our analyses of The Cancer Genome Atlas database (TCGA). Furthermore, knockdown of MCM6 significantly decreased proliferative and migratory/invasive capability of HCC cells in vitro, as well as decreased tumor volume, weight and the number of pulmonary metastases in vivo. Mechanistic analyses indicated that MCM6 promoted EMT and activated MEK/ERK signaling. More importantly, serum MCM6 levels in HCC patients were significantly higher than those in cirrhosis and healthy controls (P < 0.0001), and allowed distinguishing early recurrence with high accuracy (AUC = 0.773).

Conclusions

Our findings indicate that MCM6 predicts poor prognosis and promotes metastasis in HCC. Postoperative serum MCM6 level could be valuable to detect preclinical early recurrence, indicative of a need for more careful surveillance and aggressive therapeutic intervention.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0669-z) contains supplementary material, which is available to authorized users.

JARID2 promotes invasion and metastasis of hepatocellular carcinoma by facilitating epithelial-mesenchymal transition through PTEN/AKT signaling

JARID2 is crucial for maintenance of pluripotency and differentiation of embryonic stem cells. However, little is known about the role of JARID2 in metastasis of hepatocellular carcinoma (HCC). This study found that JARID2 expression was significantly higher in HCC tissues than that in adjacent non-tumor liver tissues (ANLTs), and its expression level correlated with HCC metastasis. High JARID2 expression was significantly correlated with multiple tumor nodules, high Edmondson-Steiner grade, microvascular invasion, advanced TNM stage and advanced BCLC stage (all P < 0.05) and indicated poor prognosis of HCC in training and validation cohorts (all P < 0.05) totaling 182 patients. High JARID2 expression was an independent and significant risk factor for disease-free survival (DFS; P = 0.017) and overall survival (OS; P = 0.041) after curative liver resection in training cohort, and also validated as an independent and significant risk factor for DFS (P = 0.033) and OS (P = 0.031) in validation cohort. Moreover, down-regulation of JARID2 dramatically inhibited HCC cell migration, invasion, proliferation in vitro and metastasis in vivo, whereas overexpression of JARID2 significantly increased migration, invasion, proliferation in vitro and metastasis in vivo. Mechanistically, the data showed that JARID2 exerted its function by repressing PTEN expression through increasing H3K27 trimethylation (H3K27me3) at PTEN promoter region, which subsequently resulted in activation of protein kinase B (AKT) and enhanced epithelial-mesenchymal transition (EMT). In conclusion, this study revealed that JARID2 promotes invasion and metastasis of HCC by facilitating EMT through PTEN/AKT signaling.

Downregulation of YAP inhibits proliferation and induces apoptosis in Eca-109 cells

A previous study reported that Yes-associated protein (YAP) gene was overexpressed in esophageal squamous cell carcinoma (ESCC); however, the exact role of YAP in ESCC remains largely unclear. The present study aimed to investigate the effects of YAP inhibition on ESCC. In order to investigate the exact role of YAP in ESCC cells, a stable YAP low-expression ESCC cell line was established using YAP-small interfering RNA. MTT assay was performed to examine the cell proliferation ability, while flow cytometry were used to detect the cell apoptosis and cell cycle distribution. In addition, reverse transcription-quantitative polymerase chain reaction and western blot analysis were applied for mRNA and protein level detection, respectively. The results suggested that YAP gene inhibition significantly repressed the ECA-109 cell proliferation and induced cell apoptosis, whereas this inhibition had no significant effects on cell cycle. Furthermore, the expression levels of cell apoptosis-associated proteins were determined in the current study, and the data demonstrated that the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein ratio and phosphorylated extracellular signal-regulated kinase expression were significantly reduced, while the p53 and caspase 3 levels were notably increased in YAP gene-inhibited ECA-109 cells. In conclusion, the current study revealed that YAP gene inhibition suppresses the proliferation and induces apoptosis in ECA-109 cells, indicating that the YAP gene serves as an oncogene in ESCC.

Prolyl hydroxylase domain protein 3 and asparaginyl hydroxylase factor inhibiting HIF-1 levels are predictive of tumoral behavior and prognosis in hepatocellular carcinoma

Hypoxia-inducible factors (HIFs) are key regulators in oxygen homeostasis. Their stabilization and activity are regulated by prolyl hydroxylase domain (PHD)-1, -2, -3 and factor inhibiting HIF (FIH). This study investigated the relation between these oxygen sensors and the clinical behaviors and prognosis of hepatocellular carcinoma (HCC). Tissue microarray and RT-PCR analysis of tumor tissues and adjacent non-tumor liver tissues revealed that mRNA and protein levels of both PHD3 and FIH were lower within tumors. The lower expression of PHD3 in tumor was associated with larger tumor size, incomplete tumor encapsulation, vascular invasion and higher Ki-67 LI (p < 0.05). The lower expression of FIH in tumor was associated with incomplete tumor encapsulation, vascular invasion, as well as higher TNM stage, BCLC stage, microvascular density and Ki-67 LI (p < 0.05). Patients with reduced expression of PHD3 or FIH had markedly shorter disease-free survival (DFS), lower overall survival (OS), or higher recurrence (p < 0.05), especially early recurrence. Patients with simultaneously reduced expression of PHD3 and FIH exhibited the least chance of forming tumor encapsulation, highest TNM stage (p < 0.0083), lowest OS and highest recurrence rate (p < 0.05). Multivariate analysis indicated that a lower expression of FIH independently predicted a poor prognosis in HCC. These findings indicate that downregulation of PHD3 and FIH in HCC is associated with more aggressive tumor behavior and a poor prognosis. PHD3 and FIH may be potential therapeutic targets for HCC treatment.

HspB5 correlates with poor prognosis in colorectal cancer and prompts epithelial-mesenchymal transition through ERK signaling

Alpha B-crystallin (HspB5) is abnormally expressed in tumor tissues and portends a poor prognosis in cancer patients. However, the role of HspB5 in colorectal cancer (CRC) is still unclear. Seventy CRC patients and 40 healthy volunteers were sampled from August 2012 to March 2015 in order to determine the clinical significance of HspB5. In vitro cellular studies were used to validate its molecular mechanisms in CRC. Our clinical data indicated that HspB5 was up-regulated, and had a positive association with TNM stage CRC patients. The expression level of HspB5 in CRC patients was closely correlated with MMP7 and E-cadherin, two core epithelial–mesenchymal transition (EMT) gene products. The in vitro studies revealed that high HspB5 expression could prompt tumor cell proliferation and invasion, as well as EMT. Gene-microarray analysis suggested three significant signaling pathways (PI3K, p38 and ERK) were involved in HspB5-induced EMT. Signal transduction pathway inhibitors and HspB5 gene knockdown models suggested that HspB5 promotes CRC tumorigenesis and EMT progression through ERK signaling pathways. In summary, HspB5 maybe trigger the EMT in CRC by activating the ERK signaling pathway. It is a potential tumor biomarker for CRC diagnosis and prognosis.

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.

SP and KLF Transcription Factors in Digestive Physiology and Diseases

Specificity proteins (SPs) and Krüppel-like factors (KLFs) belong to the family of transcription factors that contain conserved zinc finger domains involved in binding to target DNA sequences. Many of these proteins are expressed in different tissues and have distinct tissue-specific activities and functions. Studies have shown that SPs and KLFs regulate not only physiological processes such as growth, development, differentiation, proliferation, and embryogenesis, but pathogenesis of many diseases, including cancer and inflammatory disorders. Consistently, these proteins have been shown to regulate normal functions and pathobiology in the digestive system. We review recent findings on the tissue- and organ-specific functions of SPs and KLFs in the digestive system including the oral cavity, esophagus, stomach, small and large intestines, pancreas, and liver. We provide a list of agents under development to target these proteins.

Effect of metastasis suppressor 1 on H1299 cells and its clinical significance in non-small cell lung cancer

The present study aimed to investigate the effect of metastasis suppressor 1 (MTSS1) on the proliferation, migration and invasion of human H1299 non-small cell lung cancer cells and its clinical significance in non‑small cell lung cancer. The target gene MTSS1-overexpressing lentivirus (LV-MTSS1) was transfected into H1299 cells and expression of MTSS1 was detected at the mRNA and protein levels. Cell Counting Kit-8, wound healing and Transwell assays revealed that the migration and invasion activities were significantly suppressed by MTSS1, but that it had no effect on cell proliferation. In addition, MTSS1 expression in tissue microarrays including samples from 223 cases of non-small cell lung cancer was tested by immunohistochemistry to explore the correlation between MTSS1 and clinicopathological characteristics and prognosis. MTSS1 suppressed H1299 cell migration and invasion, and its expression level can be used as a new independent factor for determining the prognosis of non-small cell lung cancer.

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.

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

The transcription factor Krüppel-like factor (KLF)8 plays an important role in the formation of several human tumors, including colorectal cancer. We recently identified four-and-a-half LIM protein 2 (FHL2) as a critical inducer of the epithelial-to-mesenchymal transition (EMT) and invasion. However, the molecular mechanism by which KLF8 affects FHL2-mediated tumor proliferation, EMT and metastasis remains unknown. Here, we showed that KLF8 overexpression promoted EMT and metastatic phenotypes. KLF8 expression was stimulated by transforming growth factor (TGF)-β1. Moreover, KLF8 acted as a potential EMT inducer by stimulating vimentin expression and inducing a loss of E-cadherin in stable KLF8-transfected cells. KLF8 overexpression induced a strong increase in FHL2 expression, and a positive correlation between the expression patterns of KLF8 and FHL2 was observed in CRC cells. Promoter reporter and chromatin immunoprecipitation (ChIP) assays demonstrated that KLF8 directly bound to and activated the human FHL2 gene promoter. However, siRNA-mediated repression of FHL2 in KLF8-overexpressing cells reversed the EMT and the proliferative and metastatic phenotypes. In vivo, KLF8 promoted FHL2-mediated proliferation and metastasis via orthotopic implantation. Taken together, this work identified KLF8-induced FHL2 activation as a novel and critical signaling mechanism underlying human breast/colorectal cancer invasion and metastasis.

MTBP Promotes the Invasion and Metastasis of Hepatocellular Carcinoma by Enhancing the MDM2-Mediated Degradation of E-Cadherin

BACKGROUND

Emerging evidence suggests that MTBP plays a role in cancer development and possibly progression, but its influence on hepatocellular carcinoma (HCC) remains unclear.

METHODS

We used real-time PCR and Western blotting to investigate MTBP expression in four HCC cell lines, 120 pairs of tumor and corresponding paracarcinomatous tissues from HCC patients. Immunohistochemistry was performed to examine MTBP expression in HCC and corresponding paracarcinomatous tissues from 120 patients. E-cadherin was only examined in HCC tissues of patients mentioned above. Statistical analyses were applied to evaluate the prognostic value and associations of MTBP expression with clinical parameters. Furthermore, the MTBP gene was overexpressed in HepG2 cell and silenced by siRNA in Hu7 cell, and cell migration and invasion were detected in vitro and in vivo. Moreover, the molecular mechanism of E-cadherin regulation by MTBP was explored.

RESULTS

In this study, we first showed that MTBP protein expression is positively correlated with distant metastasis and poor prognosis in HCC patients. We also found that MTBP expression was increased in metastatic cell lines when compared with nonmetastatic cell lines. Consistent with these findings, enhanced expression of MTBP promoted HCC cell invasiveness and metastasis both in vitro and in vivo, whereas the knockdown of MTBP with small interfering RNA resulted in reduced HCC migration and invasion. Ectopic expression of MTBP in HCC cells induced epithelial-to-mesenchymal transition, whereas the silencing of MTBP had the opposite effect. Furthermore, our results show that MTBP and E-cadherin protein expression are inversely correlated in primary HCC tissues. Moreover, our findings indicate that MTBP overexpression decreases E-cadherin expression through the modulation of Mdm2 ubiquitination degradation.

CONCLUSIONS

Our data show that MTBP aggravates the invasion and metastasis of HCC by promoting the MDM2-mediated degradation of E-cadherin.

KLF8 is required for bladder cancer cell proliferation and migration

Krüppel-like factor 8 (KLF8) belongs to the Sp/KLF family of transcription factors. Recently, it is affirmed that KLF8 plays an important role in the regulation of epithelial-mesenchymal transition, which is a key process that occurs during cancer metastasis. Although the overexpression of KLF8 has been observed in several types of human cancers, the functional role of KLF8 in human bladder cancer remains unknown. Here, we investigated the effects of KLF8 knockdown on bladder cancer cell proliferation and migration in vitro. Lentivirus-mediated small interfering RNA (siRNA) targeting KLF8 specifically downregulated its expression in T24 and BT5637 bladder cancer cells. Knockdown of KLF8 significantly inhibit cell proliferation and colony formation. Cell cycle analysis showed that knockdown of KLF8 arrested T24 cells in the G0/G1 phase. Moreover, cell migration was attenuated in T24 cells after KLF8 knockdown. Furthermore, knockdown of KLF8 resulted in a reduction in vimentin and N-cadherin expression and an increase in β-catenin expression. These results indicate that KLF8 plays a crucial role in proliferation and migration of bladder cancer cells, and inhibition of KLF8 by siRNA may provide a potential therapeutic approach for gene therapy in bladder cancer.

Promyelocytic leukemia protein induces arsenic trioxide resistance through regulation of aldehyde dehydrogenase 3 family member A1 in hepatocellular carcinoma

Clinical response of hepatocellular carcinoma (HCC) to arsenic trioxide (ATO) has been poor. Promyelocytic leukemia protein (PML) is central to ATO treatment efficacy of acute promyelocytic leukemia. We examine impacts of PML expression on the effectiveness of ATO treatment in HCC. We show that increased PML expression predicts longer survival and lower cancer recurrence rates after HCC resection. However, high PML expression dampens the anti-tumor effects of ATO in HCC cells. Gene microarray analysis shows that reduced PML expression significantly down-regulates expression of aldehyde dehydrogenase 3 family member A1 (ALDH3A1). ALDH3A1 depression facilitates accumulation of ATO-induced reactive oxygen species. Chromatin immunoprecipitation analysis and promoter activity assays confirm that PML regulates ALDH3A1 expression through binding to the promoter region of ALDH3A1. Clinically, ATO treatment decreases the disease progression rate in advanced HCC patients with negative PML expression. In conclusion, PML confers a favorable prognosis in HCC patients, but it induces ATO resistance through ALDH3A1 up-regulation in HCC cells. ATO is effective for HCC patients with negative PML expression. Combined with an ALDH3A1 inhibitor, ATO may be efficacious in patients with positive PML expression.

Functional genomics screening utilizing mutant mouse embryonic stem cells identifies novel radiation-response genes

Elucidating the genetic determinants of radiation response is crucial to optimizing and individualizing radiotherapy for cancer patients. In order to identify genes that are involved in enhanced sensitivity or resistance to radiation, a library of stable mutant murine embryonic stem cells (ESCs), each with a defined mutation, was screened for cell viability and gene expression in response to radiation exposure. We focused on a cancer-relevant subset of over 500 mutant ESC lines. We identified 13 genes; 7 genes that have been previously implicated in radiation response and 6 other genes that have never been implicated in radiation response. After screening, proteomic analysis showed enrichment for genes involved in cellular component disassembly (e.g. Dstn and Pex14) and regulation of growth (e.g. Adnp2, Epc1, and Ing4). Overall, the best targets with the highest potential for sensitizing cancer cells to radiation were Dstn and Map2k6, and the best targets for enhancing resistance to radiation were Iqgap and Vcan. Hence, we provide compelling evidence that screening mutant ESCs is a powerful approach to identify genes that alter radiation response. Ultimately, this knowledge can be used to define genetic variants or therapeutic targets that will enhance clinical therapy.

Small hairpin RNA-mediated Krüppel-like factor 8 gene knockdown inhibits invasion of nasopharyngeal carcinoma

The present study aimed to characterize the expression of Krüppel-like factor 8 (KLF8) in nasopahryngeal carcinoma (NPC) cell lines and determine its effect on tumor development and invasion following KLF8 gene knockdown by small hairpin RNA (shRNA). KLF8 expression in four NPC cell lines was examined by quantitative polymerase chain reaction (qPCR) and western blotting. KLF8 was knocked down in the SUNE1-5-8F/Sh-KLF8 cell line using shRNA, and the resulting stable cell line SUNE1-5-8F-sh-KLF8 was transplanted into nude mice in order to observe tumor formation and invasion. The results obtained from qPCR and western blotting revealed that, of the four NPC cell lines, KLF8 expression was lowest in the CNE-1 cells and highest in the SUNE1-5-8F cells. The tumor xenograft mouse models revealed that SUNE1-5-8F/Sh-KLF8 cells had a reduced ability for tumor formation and invasion compared with the control group. These results demonstrated for the first time that KLF8 modulates the formation and invasive ability of nasopharyngeal carcinoma.

The activation of peroxisome proliferator-activated receptor γ is regulated by Krüppel-like transcription factors 6 & 9 under steatotic conditions

Liver steatosis is characterised by lipid droplet deposition in hepatocytes that can leads to an inflammatory and fibrotic phenotype. Peroxisome proliferator-activated receptors (PPARs) play key roles in energetic homeostasis by regulating lipid metabolism in hepatic tissue. In adipose tissue PPARγ regulates the adipocyte differentiation by promoting the expression of lipid-associated genes. Within the liver PPARγ is up-regulated under steatotic conditions; however, which transcription factors participate in its expression is not completely understood. Krüppel-like transcription factors (KLFs) regulate various cellular mechanisms, such as cell proliferation and differentiation. KLFs are key components of adipogenesis by regulating the expression of PPARγ and other proteins such as the C-terminal enhancer binding protein (C/EBP). Here, we demonstrate that the transcript levels of Klf6, Klf9 and Pparγ are increased in response to a steatotic insult in vitro. Chromatin immunoprecipitation (ChIp) experiments showed that klf6 and klf9 are actively recruited to the Pparγ promoter region under these conditions. Accordingly, the loss-of-function experiments reduced cytoplasmic triglyceride accumulation. Here, we demonstrated that KLF6 and KLF9 proteins directly regulate PPARγ expression under steatotic conditions.

Krüppel-like factors in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a disease with a high incidence and mortality rate worldwide. However, the mechanisms underlying its pathogenesis are still elusive. In recent years, studies on functions of Krüppel-like factors (KLFs) in HCC have shed new light on this field. To date, five members (KLF4, KLF6, KLF8, KLF9, and KLF17) in the KLF family have been reported to function in the pathogenesis of HCC in multiple ways, which hold the potential of deepening and widening our understanding in the initiation and progression of HCC. In this review, we focus on the functions, roles, and regulatory networks of these five KLFs in HCC, summarize key pathways, and propose areas for further investigation, with the hope that this review will provide a reliable and concise reference for readers interested in this area.

Modulation of p53 and met expression by Krüppel-like factor 8 regulates zebrafish cerebellar development

Krüppel-like factor 8 (Klf8) is a zinc-finger transcription factor implicated in cell proliferation, and cancer cell survival and invasion; however, little is known about its role in normal embryonic development. Here, we show that Klf8 is required for normal cerebellar development in zebrafish embryos. Morpholino knockdown of klf8 resulted in abnormal cerebellar primordium morphology and the induction of p53 in the brain region at 24 hours post-fertilization (hpf). Both p53-dependent reduction of cell proliferation and augmentation of apoptosis were observed in the cerebellar anlage of 24 hpf-klf8 morphants. In klf8 morphants, expression of ptf1a in the ventricular zone was decreased from 48 to 72 hpf; on the other hand, expression of atohla in the upper rhombic lip was unaffected. Consistent with this finding, Purkinje cell development was perturbed and granule cell number was reduced in 72 hpf-klf8 morphants; co-injection of p53 MO(sp) or klf8 mRNA substantially rescued development of cerebellar Purkinje cells in klf8 morphants. Hepatocyte growth factor/Met signaling is known to regulate cerebellar development in zebrafish and mouse. We observed decreased met expression in the tectum and rhombomere 1 of 24 hpf-klf8 morphants, which was largely rescued by co-injection with klf8 mRNA. Moreover, co-injection of met mRNA substantially rescued formation of Purkinje cells in klf8 morphants at 72 hpf. Together, these results demonstrate that Klf8 modulates expression of p53 and met to maintain ptf1a-expressing neuronal progenitors, which are required for the appropriate development of cerebellar Purkinje and granule cells in zebrafish embryos.

Krüppel-like factors in cancer progression: three fingers on the steering wheel

Krüppel-like factors (KLFs) comprise a highly conserved family of zinc finger transcription factors, that are involved in a plethora of cellular processes, ranging from proliferation and apoptosis to differentiation, migration and pluripotency. During the last few years, evidence on their role and deregulation in different human cancers has been emerging. This review will discuss current knowledge on Krüppel-like transcription in the epithelial-mesenchymal transition (EMT), invasion and metastasis, with a focus on epithelial cancer biology and the extensive interface with pluripotency. Furthermore, as KLFs are able to mediate different outcomes, important influences of the cellular and microenvironmental context will be highlighted. Finally, we attempt to integrate diverse findings on KLF functions in EMT and stem cell biology to ft in the current model of cellular plasticity as a tool for successful metastatic dissemination.

Krüppel-like factor 8 contributes to hypoxia-induced MDR in gastric cancer cells

We previously reported that hypoxia-induced MDR in gastric cancer (GC) cells is hypoxia-inducible factor-1 (HIF-1)-dependent. However, the exact mechanisms are still unknown. Our previous study revealed that Krüppel-like factor 8 (KLF8), a novel transcription factor, was associated with malignant phenotype in GC cells. KLF8 is overexpressed in clear cell renal carcinoma lacking von Hippel-Lindau protein function, which resulted in HIF-1 stabilization. Given this association, we hypothesized that KLF8 contributed to hypoxia-induced MDR in GC cells. Initial experiments revealed that hypoxia could increase KLF8 and HIF-1α expressions in GC cells, and KLF8 levels in GC drug-resistant cell lines were higher than in parental cell lines. Subsequent experiments showed that in normoxia, exogenous KLF8 could promote the MDR phenotype; however, blocking KLF8 expression could effectively reverse the MDR phenotype induced by hypoxia. Overexpressed KLF8 increased resistance-associated gene MDR1 mRNA levels, Bcl-2 and P-gp protein levels, and decreased Bax and caspase-3 protein levels in GC cells, and knockout KLF8 reversed these effects. Dual luciferase reporter and ChIP assays showed that KLF8 could promote MDR1 transcriptional activity by combining with KLF8 binding sites located in the upstream of MDR1 transcriptional start site. These results suggest that KLF8 is involved in hypoxia-induced MDR through inhibiting apoptosis and increasing the drug release rate by directly regulating MDR1 transcription.

This study aims to discuss whether KLF8 involves in hypoxia-induced multi-drug resistance and its mechanism. Our results showed that hypoxia could increase KLF8 expression in gastric cancer cells. Meanwhile, we found that KLF8 contributed to hypoxia-induced multi-drug resistance via regulating MDR1 directly. Through this research, we found a new target gene of KLF8 and further clarified the mechanism of multi-drug resistance happened in gastric cancer.

Krüppel -like factor 8 is a stress-responsive transcription factor that regulates expression of HuR

BACKGROUND/AIMS

HuR is an RNA-binding protein that regulates the post-transcriptional life of thousands of cellular mRNAs and promotes cell survival. HuR is expressed as two mRNA transcripts that are differentially regulated by cell stress. The goal of this study is to define factors that promote transcription of the longer alternate form.

METHODS

Effects of transcription factors on HuR expression were determined by inhibition or overexpression of these factors followed by competitive RT-PCR, gel mobility shift, and chromatin immunoprecipitation. Transcription factor expression patterns were identified through competitive RT-PCR and Western analysis. Stress responses were assayed in thapsigargin-treated proximal tubule cells and in ischemic rat kidney.

RESULTS

A previously described NF-κB site and a newly identified Sp/KLF factor binding site were shown to be important for transcription of the long HuR mRNA. KLF8, but not Sp1, was shown to bind this site and increase HuR mRNA levels. Cellular stress in cultured or native proximal tubule cells resulted in a rapid decrease of KLF8 levels that paralleled those of the long HuR mRNA variant.

CONCLUSIONS

These results demonstrate that KLF8 can participate in regulating expression of alternate forms of HuR mRNA along with NF-κB and other factors, depending on cellular contexts.

Overexpression of Dickkopf-1 predicts poor prognosis for patients with hepatocellular carcinoma after orthotopic liver transplantation by promoting cancer metastasis and recurrence

Our previous data had shown that Dickkopf-1 (DKK1) combined with β-catenin was a novel prognostic predictor for hepatocellular carcinoma (HCC) patients. However, the role and mechanism of DKK1 in HCC recurrence or metastasis remain poorly understand. This study was to assess the role of DKK1 in tumor metastasis for patients with hepatocellular carcinoma after orthotopic liver transplantation (OLT). The expression of DKK1 protein was detected in hepatic cell lines, HCC cell lines, and HCC patients after OLT with different potential of metastasis. After DKK1 expression in the HCCLM3 cells was downregulated by siRNA-mediated approach, the role of DKK1 in cell invasion and metastasis was investigated. cDNA genechip was used to analyze the differential expressed genes related with DKK1 in two pairs of HCC cells. The prognostic significance of DKK1 was further assessed by Kaplan-Meier and Cox regression analyses in 148 HCC patients after OLT. The expression of DKK1 protein was higher in the high-invasive HCC cells and HCC patients of the disease recurrence group. With the downregulation of DKK1, HCCLM3 cells showed decreased aggressiveness in vitro and lower metastatic ability in vivo. DKK1 could regulate many genes involved in biological processes and pathways related with tumor progression. Furthermore, DKK1 overexpression correlated with tumor microvessel density in clinical HCC samples. Multivariate analysis revealed that DKK1 was an independent prognostic indicator for overall survival and cumulative recurrence in this cohort of HCC patients post-OLT. Collectively, overexpression of DKK1 was implicated in invasion/metastasis of HCC after OLT and DKK1 overexpression may be potential molecular therapeutic targets for liver cancer.

HNRNPAB induces epithelial-mesenchymal transition and promotes metastasis of hepatocellular carcinoma by transcriptionally activating SNAIL

Expression of heterogeneous nuclear ribonucleoprotein AB (HNRNPAB) has been reported to be dysregulated in tumors, but its specific contributions to tumor formation and progression are not fully understood. Here, we demonstrate that HNRNPAB is overexpressed in highly metastatic cells and tumor tissues from patients with hepatocellular carcinoma (HCC) with recurrence. We found that HNRNPAB overexpression promoted epithelial-mesenchymal transition (EMT) in a manner associated with HCC metastasis in vitro and in vivo. RNA interference-mediated silencing of the EMT factor SNAIL attenuated HNRNPAB-enhanced cell invasion in vitro and lung metastasis in vivo. Mechanistically, HNRNPAB acted to transactivate SNAIL1 transcription, which in turn inhibited transcription of the pivotal SNAIL target gene E-cadherin. Overexpression of HNRNPAB in HCC samples correlated with higher SNAIL levels, shorter overall survival, and higher tumor recurrence. HNRNPAB overexpression, alone or in combination with SNAIL, was found to be a significant independent risk factor for recurrence and survival after curative resection. In conclusion, our findings define HNRNPAB as an activator of EMT and metastasis in HCC that predicts poor clinical outcomes.

KLF8 knockdown suppresses proliferation and invasion in human osteosarcoma cells

Krüppel-like factor 8 (KLF8) is a transcription factor that is important in the regulation of the cell cycle and has a critical role in oncogenic transformation and epithelial to mesenchymal transition (EMT). EMT is a key process in tumor metastasis. Although overexpression of KLF8 has been observed in a variety of human tumor types, the role of KLF8 in human osteosarcoma is yet to be elucidated. The present study aimed to investigate the biological impact of KLF8 on Saos-2 osteosarcoma cells. KLF8 gene expression was knocked down in vitro using a lentivirus-mediated small interfering (si)RNA method. Cell proliferation and cell cycle distribution were evaluated using 3-(4,5)-dimethylthiahiazo(-z-yl)-3,5-di-phenytetrazoliumromide and colony formation assays, and flow cytometry, respectively. Cell invasion was analyzed using a Transwell® invasion assay. Knockdown of KLF8 was found to significantly inhibit proliferation and invasion in osteosarcoma cells. These data suggest that KLF8 may exhibit an important role in osteosarcoma tumorigenesis and that KLF8 may be a potential therapeutic target for the treatment of osteosarcoma.