Krüppel-like Factor 4 Blocks Hepatocellular Carcinoma Dedifferentiation and Progression through Activation of Hepatocyte Nuclear Factor-6

Role of ONECUT family transcription factors in cancer and other diseases

Members of ONECUT transcription factor play an essential role in several developmental processes, however, the atypical expression of ONECUT proteins lead to numerous diseases, including cancer. ONECUT family proteins promote cell proliferation, progression, invasion, metastasis, angiogenesis, and stemness. This family of proteins interacts with other proteins such as KLF4, TGF-β, VEGFA, PRC2, SMAD3 and alters their expression involved in the regulation of various signaling pathways including Jak/Stat3, Akt/Erk, TGF-β, Smad2/3, and HIF-1α. Furthermore, ONECUT proteins are proposed as predictive biomarkers for pancreatic and gastric cancers. The present review summarizes the involvement of ONECUT family proteins in the development and progression of various human cancers and other diseases.

Strategic Replication of the Hepatic Zonation In Vitro Employing a Biomimetic Approach

The varied functions of the liver are dependent on the metabolic heterogeneity exhibited by the hepatocytes within the liver lobule spanning the porto-central axis. This complex phenomenon plays an important role in maintaining the physiological homeostasis of the liver. Standard in vitro culture models fail to mimic this spatial heterogeneity of hepatocytes, assuming a homogeneous population of cells, which leads to inaccurate translation of results. Here, we demonstrate the development of an in vitro model of hepatic zonation by mimicking the microarchitecture of the liver using a 3D printed mini bioreactor and decellularized liver matrix to provide the native microenvironmental cues. There was a differential expression of hypoxic and metabolic markers across the developed mini bioreactor, showing the establishment of gradients of oxygen, Wnt/β-catenin pathway, and other metabolic pathways. The model also showed the establishment of zone-dependent toxicity on treatment with acetaminophen. The developed model would thus be a promising avenue in the field of tissue engineering for understanding the liver physiology and pathophysiology and for drug screening to evaluate the potential of new pharmaceutical interventions.

KLF4 loss in hepatocellular carcinoma: Improving prognostic prediction and correlating immune infiltrates

Introduction: Although the molecular mechanisms of Krüpple-like factor 4 (KLF4) as a tumor suppressor in HCC tumorigenesis have been thoroughly examined, its clinical application in terms of precise prognostication and its influence on tumor immune microenvironment in patients with HCC require further investigation. Methods: Bioinformatics and immunohistochemistry (IHC) were used to validate KLF4 expressions in a tissue microarray (TMA) containing HCC samples. Using Cox regression models, independent prognostic factors were identified and employed in the development of nomograms. Decision curve analysis (DCA) demonstrated the superiority of the nomograms. GO and KEGG pathway analyses were applied to the functional study of KLF4. The GSVA program explored the link between KLF4 expression and tumor-infiltrating immune cells, and CAMOIP was used to construct KLF4 expression immune scores. Changes in immune-related gene markers were also investigated in relation to KLF4 expression. The association between immune cell infiltration and KLF4 expression was validated by IHC in TMA. Results: HCC was reported to have a notable depletion of KLF4. The absence of KLF4 was associated with advanced clinicopathological characteristics of HCC and predicted a bad prognosis for patients. Nomograms constructed using KLF4 expression, tumor differentiation, and TNM stage provided a more accurate prognostic assessment of HCC patients than TNM stage alone. KLF4 expression was associated with immunological-related functions, infiltration of macrophages, CD8⁺ T cells, and other immune cells, and elevation of immune checkpoints. Higher levels of CD8⁺ T cells and macrophage infiltration are associated with increased KLF4 expression in HCC TMA. Conclusion: KLF4 loss in HCC is a prognostic biomarker that influences the tumor immune microenvironment (TIME).

The role of transcription factors in the acquisition of the four latest proposed hallmarks of cancer and corresponding enabling characteristics

With the recent description of the molecular and cellular characteristics that enable acquisition of both core and new hallmarks of cancer, the consequences of transcription factor dysregulation in the hallmarks scheme has become increasingly evident. Dysregulation or mutation of transcription factors has long been recognized in the development of cancer where alterations in these key regulatory molecules can result in aberrant gene expression and consequential blockade of normal cellular differentiation. Here, we provide an up-to-date review of involvement of dysregulated transcription factor networks with the most recently reported cancer hallmarks and enabling characteristic properties. We present some illustrative examples of the impact of dysregulated transcription factors, specifically focusing on the characteristics of phenotypic plasticity, non-mutational epigenetic reprogramming, polymorphic microbiomes, and senescence. We also discuss how new insights into transcription factor dysregulation in cancer is contributing to addressing current therapeutic challenges.

Prognostic significance of KLF4 in solid tumours: an updated meta-analysis

Background

Kruppel-like factor 4 (KLF4) is a zinc finger-containing transcription factor predominantly expressed in terminally differentiated epithelial tissues. Many studies have shown that KLF4 has various mechanisms in different tumours; however, the prognostic role of KLF4 remains unclear.

Methods and results

We searched the relevant literature that evaluated the prognostic value of KLF4 in different cancers, and the original survival data were obtained from the text, tables or Kaplan–Meier curves for both comparative groups. Thirty studies were included in this meta-analysis, and a total of 10 malignant tumours were involved. The expression of KLF4 was not associated with the prognosis for overall survival (hazard ratio(HR)0.86, 95% confidence interval (CI): 0.65–1.13, P = 0.28), disease-free survival/recurrence-free survival/metastasis-free survival (HR 0.87, 95% CI: 0.52–1.44, P = 0.58) or disease-specific survival (HR 1.13, 95% CI: 0.44–2.87, P = 0.8).

Conclusion

This study showed that the expression of KLF4 was not related to the prognosis of the tumours that were included in the study.

Hepatocellular Carcinoma Differentiation: Research Progress in Mechanism and Treatment

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. Although progress has been made in diagnosis and treatment, morbidity and mortality continue to rise. Chronic liver disease and liver cirrhosis are still the most important risk factors for liver cancer. Although there are many treatments, it can only be cured by orthotopic liver transplantation (OLT) or surgical resection. And the worse the degree of differentiation, the worse the prognosis of patients with liver cancer. Then it can be considered that restoring a better state of differentiation may improve the prognosis. The differentiation treatment of liver cancer is to reverse the dedifferentiation process of hepatocytes to liver cancer cells by means of drugs, improve the differentiation state of the tumor, and restore the normal liver characteristics, so as to improve the prognosis. Understanding the mechanism of dedifferentiation of liver cancer can provide ideas for drug design. Liver enrichment of transcription factors, imbalance of signal pathway and changes of tumor microenvironment can promote the occurrence and development of liver cancer, and restoring its normal level can inhibit the malignant behavior of tumor. At present, some drugs have been proved to be effective, but more clinical data are needed to support the effectiveness and reliability of drugs. The differentiation treatment of liver cancer is expected to become an important part of the treatment of liver cancer in the future.

USP11 degrades KLF4 via its deubiquitinase activity in liver diseases

Krüppel‐like factor 4 (KLF4) is a zinc‐finger containing DNA‐binding transcription factor involved in tumorigenesis and acts as a tumour suppressor or an oncogene depending on the tissue. In hepatocellular carcinoma (HCC), KLF4 has been considered as a tumour suppressor, although the mechanism underlying its action remains largely unknown. In this study, we identified the ubiquitin‐specific peptidase USP11 as a KLF4‐interacting deubiquitinating enzyme using a proteomic approach. USP11 destabilizes KLF4 through the removal of K63‐dependent polyubiquitination, thereby inhibiting KLF4 expression. We also provide mechanistic insights into KLF4 degradation and show that USP11 depletion inhibits growth and chemoresistance of HCC cells by enhancing KLF4 stability. Importantly, lipid content was reduced and genes involved in fatty acid metabolism were down‐regulated in an in vitro steatosis conditions upon USP11 knockout. Finally, elevated USP11 and reduced KLF4 levels were detected both in a hepatic steatosis in vitro model and in public clinical data of non‐alcoholic fatty liver disease and HCC patients. Collectively, these findings suggest that USP11, as KLF4‐binding partner, is an important mediator of hepatic tumorigenesis that functions via degradation of KLF4 and is a potential treatment target for liver diseases.

Tumor supernatant derived from hepatocellular carcinoma cells treated with vincristine sulfate have therapeutic activity

Vincristine sulfate (VCR), a commonly used chemotherapeutic agent, kills cancer cells as well as the normal cells for its cytotoxicity. But it is still unclear whether it can exert therapeutic effect on untreated cancer cells by changing the supernatant of cancer cells. Here, we explored the subsequent cascade effects of the supernatant of cancer cells that were transiently treated with VCR on untreated tumor cells and its responsible mechanisms. VCR and three different hepatocellular carcinoma (HCC) cell lines were used for an experiment. The experiment was conducted in vitro to eliminate the body's internal factors and the effects of the immune system. The results suggested that drug-free tumor supernatant (TSN) could promote the differentiation, repress the transcription of liver cancer stem cell's markers and the proliferation in SMMC-7721, Bel-7402 and Huh7 cells. Furthermore, we found that the TSN could abolish YAP1 transcriptional activity to inhibit the proliferation and increase the transcriptional activity of HNF4α to promote the differentiation in SMMC-7721 and Bel-7402 cells. In conclusion, the TSN could inhibit the proliferation and induce differentiation in different HCC cells.

The association between KLF4 as a tumor suppressor and the prognosis of hepatocellular carcinoma after curative resection

Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor in klfs family, is known for its crucial role in regulating cell growth, proliferation, and differentiation. This research aimed to explore the prognostic significance of KLF4 in hepatocellular carcinoma’s (HCC) patients after curative resection and the role of KLF4 in HCC progression. There were 185 HCC patients who had hepatectomy from July 2010 to July 2011 included in this study. KLF4 expression was detected by microarray immunohistochemical technique, western blot, and qRT-PCR. Then, the correlation between the prognosis of patients and KLF4 expression was evaluated based on patients’ follow-up data. The research found KLF4 expression was significantly downregulated in HCC tissues compared to para-tumorous tissues. More importantly, the overall survival rate (OS) and recurrence-free survival rate (RFS) of HCC patients with low KLF4 expression were both significantly decreased compared to those with a high level of KLF4. Further function and mechanism analysis showed that KLF4 could inhibit the proliferation, migration, invasion and epithelial-mesenchymal transition of HCC cells. The study revealed that KLF4 was not only a tumor suppressor in HCC but also can be regarded as a valuable prognostic factor and potential biological target for diagnosis and treatment in HCC patients.

Dedifferentiation of hepatocellular carcinoma: molecular mechanisms and therapeutic implications

Hepatocellular carcinoma (HCC) is a common cancer with high morbidity and mortality. Poorer differentiation status indicates worse prognosis of HCC patients. Regain of better differentiation status may improve the prognosis. Differentiation therapy for HCC is based on the fact that agents may reverse the dedifferentiation process from hepatocytes to HCC cells and thus improve tumor differentiation status. Reversal of progenitor-like property and restoration of hepatic characteristics are main objectives of HCC differentiation therapy. Comprehending the mechanisms of HCC dedifferentiation provides ideas for drug design. Diverse dysregulated molecules and signalings cooperatively cause HCC dedifferentiation. Dysregulation of liver enriched transcription factors, especially hepatocyte nuclear factor 4α, was a critical determinant of HCC dedifferentiation. Aberrant pivotal signaling molecules such as transforming factor-β, β-catenin and Yes-associated protein caused disordered signalings, which promoted HCC dedifferentiation. Loss of epithelial morphology during epithelial-mesenchymal transition (EMT) concurred with HCC dedifferentiation. Some EMT-related molecules exerted double-sided role in concurrently inducing EMT and HCC dedifferentiation. Besides, microRNAs (e.g. miR-122 and miR-148a) as well as some impressive proteins (i.e. KLF4, gankyrin and CHD1L) functioned in manipulating HCC differentiation status. Restoring normal expression levels of these molecules could induce HCC differentiation and inhibited malignant tumor behaviors. Based on the knowledge above, some agents have been found effective in lab, but need more data to support their reliability. Additionally, peretinoin as a potential drug is in progress of several phase III clinical trials. It's promising that differentiation therapy for HCC may be a part of options in future HCC treatment.

Tuning up Transcription Factors for Therapy

The recent developments in the delivery and design of transcription factors put their therapeutic applications within reach, exemplified by cell replacement, cancer differentiation and T-cell based cancer therapies. The success of such applications depends on the efficacy and precision in the action of transcription factors. The biophysical and genetic characterization of the paradigmatic prokaryotic repressors, LacI and TetR and the designer transcription factors, transcription activator-like effector (TALE) and CRISPR-dCas9 revealed common principles behind their efficacy, which can aid the optimization of transcriptional activators and repressors. Further studies will be required to analyze the linkage between dissociation constants and enzymatic activity, the role of phase separation and squelching in activation and repression and the long-range interaction of transcription factors with epigenetic regulators in the context of the chromosomes. Understanding these mechanisms will help to tailor natural and synthetic transcription factors to the needs of specific applications.

Post-transplant infection improves outcome of hepatocellular carcinoma patients after orthotopic liver transplantation

BACKGROUND

Tumor recurrence after orthotopic liver transplantation (OLT) remains a serious threat for long-term survival of the recipients with hepatocellular carcinoma (HCC), since very few factors or measures have shown impact on overcoming HCC recurrence after OLT. Postoperative infection suppresses tumor recurrence and improves patient survival in lung cancer and malignant glioma probably via stimulating the immune system. Post-transplant infection (PTI), a common complication, is deemed to be harmful for the liver transplant recipients from a short-term perspective. Nevertheless, whether PTI inhibits HCC recurrence after OLT and prolongs the long-term survival of HCC patients needs to be clarified.

AIM

To investigate the potential influence of PTI on the survival and tumor recurrence of patients with HCC after OLT.

METHODS

A total of 238 patients with HCC who underwent OLT between August 2002 and July 2016 at our center were retrospectively included and accordingly subdivided into a PTI group (53 patients) and a non-PTI group (185 patients). Univariate analyses, including the differences of overall survival (OS), recurrence-free survival (RFS), and post-recurrence survival (PRS), between the PTI and non-PTI subgroups as well as survival curve analysis were performed by the Kaplan-Meier method, and the differences were compared using the log rank test. The variables with a P-value < 0.1 in univariate analyses were included in the multivariate survival analysis by using a Cox proportional-hazards model.

RESULTS

The 1-, 3-, and 5-year OS and RFS rates of the whole cohort were 86.6%, 69.0%, and 63.6%, and 75.7%, 60.0%, and 57.3%, respectively. The 1-, 3-, and 5-year OS rates for the PTI patient group (96.0%, 89.3%, and 74.0%) were significantly higher than those for the non-PTI group (84.0%, 63.4%, and 60.2%) (P = 0.033). The absence of PTI was an independent risk factor for dismal OS (relative risk [RR] = 2.584, 95%CI: 1.226-5.449) and unfavorable RFS (RR = 2.683, 95%CI: 1.335-5.390). Subgroup analyses revealed that PTI remarkably improved OS (P = 0.003) and RFS (P = 0.003) rates of HCC patients with vascular invasion (IV), but did not impact on OS (P = 0.404) and RFS (P = 0.304) of patients without VI. Among the patients who suffered post-transplant tumor recurrence, patients with PTI showed significantly better OS (P = 0.026) and PRS (P = 0.042) rates than those without PTI.

CONCLUSION

PTI improves OS and RFS of the transplant HCC patients at a high risk for post-transplant death and tumor recurrence, which is attributed to suppressive effect of PTI on HCC recurrence.

Mechano-signalling, induced by fullerene C60 nanofilms, arrests the cell cycle in the G2/M phase and decreases proliferation of liver cancer cells

INTRODUCTION AND OBJECTIVE

Degradation of the extracellular matrix (ECM) changes the physicochemical properties and dysregulates ECM-cell interactions, leading to several pathological conditions, such as invasive cancer. Carbon nanofilm, as a biocompatible and easy to functionalize material, could be used to mimic ECM structures, changing cancer cell behavior to perform like normal cells.

METHODS

Experiments were performed in vitro with HS-5 cells (as a control) and HepG2 and C3A cancer cells. An aqueous solution of fullerene C60 was used to form a nanofilm. The morphological properties of cells cultivated on C60 nanofilms were evaluated with light, confocal, electron and atomic force microscopy. The cell viability and proliferation were measured by XTT and BrdU assays. Immunoblotting and flow cytometry were used to evaluate the expression level of proliferating cell nuclear antigen and determine the number of cells in the G2/M phase.

RESULTS

All cell lines were spread on C60 nanofilms, showing a high affinity to the nanofilm surface. We found that C60 nanofilm mimicked the niche/ECM of cells, was biocompatible and non-toxic, but the mechanical signal from C60 nanofilm created an environment that affected the cell cycle and reduced cell proliferation.

CONCLUSION

The results indicate that C60 nanofilms might be a suitable, substitute component for the niche of cancer cells. The incorporation of fullerene C60 in the ECM/niche may be an alternative treatment for hepatocellular carcinoma.

Aberrant lipid metabolism as a therapeutic target in liver cancer

INTRODUCTION

Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers. Progress has been made in treatment of HCC; however, improved outcomes are much needed. The increased metabolic needs of cancer cells underscore the importance of metabolic pathways in cancer cell survival. Lipid metabolism has a role in HCC development; aberrant overexpression of several key enzymes is seen in many solid human tumors. Areas covered: We discuss aberrant lipid metabolism and the promise of multiple targets, in particular related to HCC treatment. We searched PubMed and clinicaltrials.gov for published and unpublished studies from 2000 to 2019. These terms were used: lipids, fatty acid metabolism, lipid metabolism, liver cancer, HCC, de novo fatty acid synthesis, ATP citrate lyase, stearoyl CoA denaturase, fatty acid synthase, acetyl coenzyme A carboxylase, CD147, KLF4, monoglyceride lipase, AMP activated protein kinase. Expert opinion: The importance of dysregulation of fatty acid synthesis in cancer is a growing area of research. HCC demonstrates significant alteration in lipid metabolism, representing great potential as a target for novel therapeutics. Various agents have demonstrated promising anti-neoplastic activity. This strategy deserves further development for improved outcomes.

KLF4-Mediated CDH3 Upregulation Suppresses Human Hepatoma Cell Growth and Migration via GSK-3β Signaling

P-cadherin (CDH3), a classical cell adhesion molecule involved in tissue integrity and cell localization, has been implicated in many types of cancer. However, little is known about its function and regulatory mechanism in hepatocellular carcinoma (HCC). Here we report that CDH3 was positively regulated by kr¨uppel-like transcription factor 4 (KLF4), which is a crucial tumor suppressor gene in HCC, at mRNA level in HCC cell lines. Luciferase reporter assay and chromatin immunoprecipitation assay indicated that KLF4 directly bound to CDH3 promoter and transcriptionally activated CDH3 expression. Consistently, CDH3 expression was closely related with KLF4 expression in patients' samples and both proteins exhibited a downregulated expression pattern in cancer samples. Functionally, enforced CDH3 expression suppressed and silenced CDH3 expression promoted HCC cell growth and migration in vitro. Mechanistically, we observed that GSK-3β was regulated by CDH3 and may function as a possible downstream effector of CDH3. Knockdown of GSK-3β showed a similar phenotype with CDH3 silencing. Taken together, these findings establish the KLF4/CDH3/GSK-3β axis as an important regulatory mechanism in HCC development.

Krüppel-like factor 4 expression in solid tumor prognosis: A meta-analysis

BACKGROUND

Accumulating studies have demonstrated that Krüppel-like factor 4 (KLF4) can act as a tumor suppressor or oncogene in the carcinogenesis of diverse cancers. The prognostic value of KLF4 in various human solid cancers remains controversial. Thus, the present meta-analysis was conducted to evaluate the prognostic value of KLF4 in solid tumors.

METHODS

Eligible literature was retrieved by searching the PubMed, Embase, and Cochrane Library. Combined hazard ratios (HRs) for overall survival (OS) and disease-free survival (DFS) were assessed using fixed-effects and random-effects models. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity. In addition, publication bias was assessed using Begg's funnel plot and Egger's regression asymmetry test.

RESULTS

The 22 eligible studies finally enrolled a total of 2988 patients to assess the prognostic value of KLF4 in solid tumors. Low KLF4 expression was clearly related to worse OS (HR = 1.71, 95% confidence interval [CI] = 1.30-2.24, P < 0.001) and DFS (HR = 1.74, 95% CI = 1.34-2.26, P < 0.001), indicating that low KLF4 expression could be an independent prognostic factor for poor survival in solid cancers.

CONCLUSION

KLF4 might be a potential marker to predict prognosis in solid cancer patients.

Differentiation-inducing therapeutic effect of Notch inhibition in reversing malignant transformation of liver normal stem cells via MET

Background

Liver cancer stem cells (LCSCs) are the key factors for cancer metastasis, recurrent, and drug resistance. LCSCs are originated from either hepatocytes dedifferentiation or differentiation arresting of liver normal stem cells (LNSCs). Differentiation-inducing therapy is a novel strategy in solid tumors. Furthermore, Notch signaling pathway has been proved to play important role in the process of hepatocytes differentiation. In previous study, a malignant transformation cellular model of LNSCs has been built up, and in this study we are trying to illustrate whether inhibition of Notch can reverse this malignant tendency and drive these malignant cells back to differentiate into mature hepatocytes.

Results

Inhibition of Notch signaling pathway can down-regulate the stemness-related cancer markers, lower the proliferative status, alleviate the invasive characteristic, or attenuate the metastasis tendency. What is more, it can help the malignantly transformed cells to regain the mature hepatic function of glucagon synthesis, urea metabolism, albumin production, and indocyanine-green (ICG) clearance.

Materials and Methods

HOX transcript antisense RNA (HOTAIR) expression was enhanced in LNSCs via lentivirus transduction to set up the malignant transformation cellular model. Then, a Notch inhibitor was applied to induce malignantly transformed cells differentiate into mature hepatocytes, and malignant abilities of proliferation, invasiveness, tumorigenesis as well as mature hepatocyte function were observed and compared.

Conclusions

The data demonstrate that the anti-tumor effects of Notch inhibition may lie not only on killing the cancer cells or LCSCs directly, it can also induce the LCSCs differentiation into mature hepatocytes via mesenchymal-epithelial transition (MET) progress or downgrade the malignancy.

Krüppel-like Factor 4 Suppresses Serine/Threonine Kinase 33 Activation and Metastasis of Gastric Cancer through Reversing Epithelial-Mesenchymal Transition

Background: Cancers with aberrant expression of Serine/threonine kinase 33 (STK33) has been reported to be particularly aggressive. However, its expression, clinical significance, and biological functions in gastric cancer remain largely unknown. In the present study, we determined the expression and function of STK33 in gastric cancer and delineated the clinical significance of the Krüppel-like factor 4 (KLF4)/STK33 signaling pathway.Methods: STK33 expression and its association with multiple clinicopathologic characteristics were analyzed immunohistochemically in human gastric cancer specimens. STK33 knockdown and overexpression were used to dissect the underlying mechanism of its functions in gastric cancer cells. Regulation and underlying mechanisms of STK33 expression by KLF4 in gastric cancer cells were studied using cell and molecular biological methods.Results: Drastically higher expression of STK33 was observed in gastric cancer and gastric intraepithelial neoplasia tissues compared with adjacent normal gastric tissues. Increased STK33 expression correlated directly with tumor size, lymph node, and distant metastasis; and patients with low STK33 expression gastric cancer were predicted to have a favorable prognosis. Enforced expression of STK33 promoted gastric cancer cell proliferation, migration, and invasion in vitro and in vivo, whereas reduced STK33 did the opposite. Moreover, STK33 promoted epithelial-mesenchymal transition (EMT) in vitro Mechanistically, KLF4 transcriptionally inhibited STK33 expression in gastric cancer cells. KLF4-mediated inhibition of gastric cancer cell invasion was reversed by upregulation of STK33 expression.Conclusions: STK33 has pro-tumor function and is a critical downstream mediator of KLF4 in gastric cancer. STK33 may serve as a potential prognostic marker and therapeutic target for gastric cancer. Clin Cancer Res; 24(10); 2440-51. ©2018 AACR.

The Prognostic Value of Decreased KLF4 in Digestive System Cancers: A Meta-Analysis from 17 Studies

Background

The prognostic value of loss of Krüppel-like factor 4 (KLF4) expression in digestive system cancers has not reached a consensus. This study aimed for a comprehensive investigation of the internal associations between KLF4 expression loss and prognostic implications in patients with digestive system cancers.

Methods

We searched for all relevant literatures in the electronic databases until February 1, 2017. The degree of association between KLF4 and prognosis was evaluated by pooled hazard ratios (HRs) as well as relevant 95% confidence intervals (95% CIs).

Results

Seventeen eligible studies with 2118 patients revealed that loss of KLF4 expression was connected with poor prognosis, with the pooled HRs of 1.61 (95% CI: 1.17–2.20, P = 0.003) for the overall survival (OS) and 1.99 (95% CI: 1.12–3.52, P = 0.001) for the disease-free survival (DFS)/recurrence-free survival (RFS)/metastasis-free survival (MFS). Additionally, loss of KLF4 expression was also related to a worse disease-special survival (DSS) yielding a pooled HR of 1.73 (95% CI: 1.08–2.77, P = 0.022).

Conclusion

Our findings suggest that loss of KLF4 expression is correlated with a bad outcome in most digestive system cancers, apart from esophagus squamous cell carcinoma (ESCC).

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.

Krüppel-like factor 4 contributes to the pathogenesis of mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive subtype of B-cell non-Hodgkin lymphoma (NHL) with poor prognosis. Krüppel-like factor 4 (KLF4) has been reported as a bi-regulator in malignancies, but little is known about its role in MCL. Here, we showed that KLF4 was downregulated in three MCL cell lines and lymph nodes from MCL patients, which resulted in a negative prognosis. We also found that the regulation of KLF4 could inhibit the proliferation and induce apoptosis of Jeko-1 cells. The lentivirally over-expressed KLF4 protein was found bind to β-catenin and could inhibit downstream molecules such as cyclinD1 and c-Myc. Furthermore, 5-azacytidine could decrease the expression of methyltransferase-1 (DNMT-1) and restore the KLF4 expression in MCL cell lines, indicating that methylation might play an important role in the downregulation of KLF4. KLF4 may be a potential therapeutic target as a tumor suppressor in MCL.

RYBP Expression Is Regulated by KLF4 and Sp1 and Is Related to Hepatocellular Carcinoma Prognosis

The expression of Ring1- and YY1-binding protein (RYBP) is reduced in several human cancers, but the molecular mechanism(s) have remained elusive. In this study, we used human hepatocellular carcinoma (HCC) cell lines and tissue specimens to study the mechanism and herein report several new findings. First, we cloned and characterized the basal promoter region of the human RYBP gene. We found that the decreased RYBP expression in HCC tissues was not due to promoter sequence variation/polymorphisms or CpG dinucleotide methylation. We identified two transcription factors, KLF4 and Sp1, which directly bind the promoter region of RYBP to induce and suppress RYBP transcription, respectively. We mapped the binding sites of KLF4 and Sp1 on the RYBP promoter. Studies in vitro showed that KLF4 suppresses whereas Sp1 promotes HCC cell growth through modulating RYBP expression. Deregulated KLF4 and Sp1 contributed to decreased expression of RYBP in HCC tumor tissues. Our studies of human HCC tissues indicated that a diminished RYBP level in the tumor (in association with altered KLF4 and Sp1 expression) was statistically associated with a larger tumor size, poorer differentiation, and an increased susceptibility to distant metastasis. These findings help to clarify why RYBP is decreased in HCC and indicate that deregulated KLF4, Sp1, and RYBP may lead to a poorer prognosis. Our findings support the idea that RYBP may represent a target for cancer therapy and suggest that it may be useful as a prognostic biomarker for HCC, either alone or in combination with KLF4 and Sp1.