Transcriptional repression of WEE1 by Kruppel-like factor 2 is involved in DNA damage-induced apoptosis

Off-target pharmacological activity at various kinases: Potential functional and pathological side effects

In drug discovery, during the lead optimization and candidate characterization stages, novel small molecules are frequently evaluated in a battery of in vitro pharmacology assays to identify potential unintended, off-target interactions with various receptors, transporters, ion channels, and enzymes, including kinases. Furthermore, these screening panels may also provide utility at later stages of development to provide a mechanistic understanding of unexpected safety findings. Here, we present a compendium of the most likely functional and pathological outcomes associated with interaction(s) to a panel of 95 kinases based on an extensive curation of the scientific literature. This panel of kinases was designed by AbbVie based on safety-related data extracted from the literature, as well as from over 20 years of institutional knowledge generated from discovery efforts. For each kinase, the scientific literature was reviewed using online databases and the most often reported functional and pathological effects were summarized. This work should serve as a practical guide for small molecule drug discovery scientists and clinical investigators to predict and/or interpret adverse effects related to pharmacological interactions with these kinases.

Role of non-coding RNAs and exosomal non-coding RNAs in retinoblastoma progression

Retinoblastoma (RB) is a rare aggressive intraocular malignancy of childhood that has the potential to affect vision, and can even be fatal in some children. While the tumor can be controlled efficiently at early stages, metastatic tumors lead to high mortality. Non-coding RNAs (ncRNAs) are implicated in a number of physiological cellular process, including differentiation, proliferation, migration, and invasion, The deregulation of ncRNAs is correlated with several diseases, particularly cancer. ncRNAs are categorized into two main groups based on their length, i.e. short and long ncRNAs. Moreover, ncRNA deregulation has been demonstrated to play a role in the pathogenesis and development of RB. Several ncRNAs, such as miR-491-3p, miR-613,and SUSD2 have been found to act as tumor suppressor genes in RB, but other ncRNAs, such as circ-E2F3, NEAT1, and TUG1 act as tumor promoter genes. Understanding the regulatory mechanisms of ncRNAs can provide new opportunities for RB therapy. In the present review, we discuss the functional roles of the most important ncRNAs in RB, their interaction with the genes responsible for RB initiation and progression, and possible future clinical applications as diagnostic and prognostic tools or as therapeutic targets.

Quantitative Phosphoproteomics and Acetylomics of Safranal Anticancer Effects in Triple-Negative Breast Cancer Cells

Safranal, as an aroma in saffron, is one of the cytotoxic compounds in saffron that causes cell death in triple-negative breast cancer cells. Our recent research reported the anti-cancer effects of safranal, which further demonstrated its impact on protein translation, mitochondrial dysfunction, and DNA fragmentation. To better understand the underlying mechanisms, we identified acetylated and phosphorylated peptides in safranal-treated cancer cells. We conducted a comprehensive phosphoproteomics and acetylomics analysis of safranal-treated MDA-MB-231 cells by using a combination of TMT labeling and enrichment methods including titanium dioxide and immunoprecipitation. We provide a wide range of phosphoproteome regulation in different signaling pathways that are disrupted by safranal treatment. Safranal influences the phosphorylation level on proteins involved in DNA replication and repair, translation, and EGFR activation/accumulation, which can lead the cells into apoptosis. Safranal causes DNA damage which is followed by the activation of cell cycle checkpoints for DNA repair. Over time, checkpoints and DNA repair are inhibited and cells are under a mitotic catastrophe. Moreover, safranal prevents repair by the hypo-acetylation of H4 and facilitates the transcription of proapoptotic genes by hyper-acetylation of H3, which push the cells to the brink of death.

Identifying General Tumor and Specific Lung Cancer Biomarkers by Transcriptomic Analysis

The bioinformatic pipeline previously developed in our research laboratory is used to identify potential general and specific deregulated tumor genes and transcription factors related to the establishment and progression of tumoral diseases, now comparing lung cancer with other two types of cancer. Twenty microarray datasets were selected and analyzed separately to identify hub differentiated expressed genes and compared to identify all the deregulated genes and transcription factors in common between the three types of cancer and those unique to lung cancer. The winning DEGs analysis allowed to identify an important number of TFs deregulated in the majority of microarray datasets, which can become key biomarkers of general tumors and specific to lung cancer. A coexpression network was constructed for every dataset with all deregulated genes associated with lung cancer, according to DAVID’s tool enrichment analysis, and transcription factors capable of regulating them, according to oPOSSUM´s tool. Several genes and transcription factors are coexpressed in the networks, suggesting that they could be related to the establishment or progression of the tumoral pathology in any tissue and specifically in the lung. The comparison of the coexpression networks of lung cancer and other types of cancer allowed the identification of common connectivity patterns with deregulated genes and transcription factors correlated to important tumoral processes and signaling pathways that have not been studied yet to experimentally validate their role in lung cancer. The Kaplan–Meier estimator determined the association of thirteen deregulated top winning transcription factors with the survival of lung cancer patients. The coregulatory analysis identified two top winning transcription factors networks related to the regulatory control of gene expression in lung and breast cancer. Our transcriptomic analysis suggests that cancer has an important coregulatory network of transcription factors related to the acquisition of the hallmarks of cancer. Moreover, lung cancer has a group of genes and transcription factors unique to pulmonary tissue that are coexpressed during tumorigenesis and must be studied experimentally to fully understand their role in the pathogenesis within its very complex transcriptomic scenario. Therefore, the downstream bioinformatic analysis developed was able to identify a coregulatory metafirm of cancer in general and specific to lung cancer taking into account the great heterogeneity of the tumoral process at cellular and population levels.

Suppression of tumor metastasis by a RECK-activating small molecule

RECK encodes a membrane-anchored protease-regulator which is often downregulated in a wide variety of cancers, and reduced RECK expression often correlates with poorer prognoses. In mouse models, forced expression of RECK in tumor xenografts results in suppression of tumor angiogenesis, invasion, and metastasis. RECK mutations, however, are rare in cancer genomes, suggesting that agents that re-activate dormant RECK may be of clinical value. We found a potent RECK-inducer, DSK638, that inhibits spontaneous lung metastasis in our mouse xenograft model. Induction of RECK expression involves SP1 sites in its promoter and may be mediated by KLF2. DSK638 also upregulates MXI1, an endogenous MYC-antagonist, and inhibition of metastasis by DSK638 is dependent on both RECK and MXI1. This study demonstrates the utility of our approach (using a simple reporter assay followed by multiple phenotypic assays) and DSK638 itself (as a reference compound) in finding potential metastasis-suppressing drugs.

Epigenetically silenced apoptosis-associated tyrosine kinase (AATK) facilitates a decreased expression of Cyclin D1 and WEE1, phosphorylates TP53 and reduces cell proliferation in a kinase-dependent manner

Silencing of the Apoptosis associated Tyrosine Kinase gene (AATK) has been described in cancer. In our study, we specifically investigated the epigenetic inactivation of AATK in pancreatic adenocarcinoma, lower grade glioma, lung, breast, head, and neck cancer. The resulting loss of AATK correlates with impaired patient survival. Inhibition of DNA methyltransferases (DNMTs) reactivated AATK in glioblastoma and pancreatic cancer. In contrast, epigenetic targeting via the CRISPR/dCas9 system with either EZH2 or DNMT3A inhibited the expression of AATK. Via large-scale kinomic profiling and kinase assays, we demonstrate that AATK acts a Ser/Thr kinase that phosphorylates TP53 at Ser366. Furthermore, whole transcriptome analyses and mass spectrometry associate AATK expression with the GO term 'regulation of cell proliferation'. The kinase activity of AATK in comparison to the kinase-dead mutant mediates a decreased expression of the key cell cycle regulators Cyclin D1 and WEE1. Moreover, growth suppression through AATK relies on its kinase activity. In conclusion, the Ser/Thr kinase AATK represses growth and phosphorylates TP53. Furthermore, expression of AATK was correlated with a better patient survival for different cancer entities. This data suggests that AATK acts as an epigenetically inactivated tumor suppressor gene.

Targeting DNA repair pathway in cancer: Mechanisms and clinical application

Over the last decades, the growing understanding on DNA damage response (DDR) pathways has broadened the therapeutic landscape in oncology. It is becoming increasingly clear that the genomic instability of cells resulted from deficient DNA damage response contributes to the occurrence of cancer. One the other hand, these defects could also be exploited as a therapeutic opportunity, which is preferentially more deleterious in tumor cells than in normal cells. An expanding repertoire of DDR-targeting agents has rapidly expanded to inhibitors of multiple members involved in DDR pathways, including PARP, ATM, ATR, CHK1, WEE1, and DNA-PK. In this review, we sought to summarize the complex network of DNA repair machinery in cancer cells and discuss the underlying mechanism for the application of DDR inhibitors in cancer. With the past preclinical evidence and ongoing clinical trials, we also provide an overview of the history and current landscape of DDR inhibitors in cancer treatment, with special focus on the combination of DDR-targeted therapies with other cancer treatment strategies.

Transcription factor KLF2 enhances the sensitivity of breast cancer cells to cisplatin by suppressing kinase WEE1

Cisplatin is an effective chemotherapeutic agent in facilitating the inhibition of proliferation, migration, and invasion in cancerous cells. However, the detailed mechanism of the regulation by cisplatin of human breast cancer cells is still unclear. This study aimed to investigate the mechanism of kruppel-like factor 2 (KLF2) transcription factor in cisplatin therapy for breast cancer. RT-qPCR was performed to quantify the expression of KLF2 and WEE1 in clinical tissue samples from breast cancer patients and in MDA-MB-231 cells. ChIP assay and dual-luciferase reporter assay were used to analyze the potential-binding sites of KLF2 and WEE1 promoter. Gain- or loss-of-function approaches were used to manipulate KLF2 and WEE1 in cisplatin-treated MDA-MB-231 cells, and the mechanism of KLF2 in breast cancer was evaluated both via CCK-8 assay, flow cytometry, Transwell assay, and Western blot. Further validation of the KLF2 was performed on nude mouse models. Breast cancer tissues and cells showed a relative decline of KLF2 expression and abundant WEE1 expression. Cisplatin inhibited the proliferation, migration, and invasion of MDA-MB-231 cells. Overexpression of KLF2 enhanced the inhibitory effect of cisplatin on the malignant characteristics of MDA-MB-231 cells in vitro. KLF2 targeted WEE1 and negatively regulated its expression, thus enhancing the sensitivity to cisplatin of breast cancer cells as well as tumor-bearing mice. Overall, these results suggest that KLF2 can potentially inhibit WEE1 expression and sensitize breast cancer cells to cisplatin, thus presenting a promising adjunct treatment.

The Staufen1-dependent cell cycle regulon or how a misregulated RNA-binding protein leads to cancer

In recent years, an increasing number of reports have linked the RNA-binding protein Staufen1 (STAU1) to the control of cell decision making. In non-transformed cells, STAU1 balances the expression of messenger RNA (mRNA) regulons that regulate differentiation and well-ordered cell division. Misregulation of STAU1 expression and/or functions changes the fragile balance in the expression of pro- and anti-proliferative and apoptotic genes and favours a novel equilibrium that supports cell proliferation and cancer development. The misregulation of STAU1 functions causes multiple coordinated modest effects in the post-transcriptional regulation of many RNA targets that code for cell cycle regulators, leading to dramatic consequences at the cellular level. The new tumorigenic equilibrium in STAU1-mediated gene regulation observed in cancer cells can be further altered by a slight increase in STAU1 expression that favours expression of pro-apoptotic genes and cell death. The STAU1-dependent cell cycle regulon is a good model to study how abnormal expression of an RNA-binding protein promotes cell growth and provides an advantageous selection of malignant cells in the first step of cancer development.

A novel histone deacetylase inhibitor MPT0L184 dysregulates cell-cycle checkpoints and initiates unscheduled mitotic signaling

Aberrant alteration of epigenetic information disturbs chromatin structure and gene function, thereby facilitating cancer development. Several drugs targeting histone deacetylases (HDACs), a group of epigenetic enzymes, have been approved for treating hematologic malignancies in the clinic. However, patients who suffer from solid tumors often respond poorly to these drugs. In this study, we report a selective entinostat derivative, MPT0L184, with potent cancer-killing activity in both cell-based and mouse xenograft models. A time-course analysis of cell-cycle progression revealed that MPT0L184 treatment elicited an early onset of mitosis but prevented the division of cells with duplicated chromosomes. We show that MPT0L184 possessed potent inhibitory activity toward HDAC1 and 2, and its HDAC-inhibitory activity was required for initiating premature mitotic signaling. HDAC inhibition by MPT0L184 reduced WEE1 expression at the transcription level. In addition, MPT0L184 treatment also downregulated ATR-mediated CHK1 phosphorylation independent of HDAC inhibition. Furthermore, gastric cancer cells resistant to HDAC inhibitors were vulnerable to MPT0L184. Taken together, our study discovers MPT0L184 as a novel HDAC inhibitor that can trigger premature mitosis and potentially counteract drug resistance of cancers.

KLF7: a new candidate biomarker and therapeutic target for high-grade serous ovarian cancer

BACKGROUND

In spite of great progress in the surgical and clinical management, until now no significant improvement in overall survival of High-Grade Serous Ovarian Cancer (HGSOC) patients has been achieved. Important aspects for disease control remain unresolved, including unclear pathogenesis, high heterogeneity and relapse resistance after chemotherapy. Therefore, further research on molecular mechanisms involved in cancer progression are needed to find new targets for disease management. The Krüppel-like factors (KLFs) are a family of transcriptional regulators controlling several basic cellular processes, including proliferation, differentiation and migration. They have been shown to play a role in various cancer-relevant processes, in a context-dependent way.

METHODS

To investigate a possible role of KLF family members as prognostic biomarkers, we carried out a bioinformatic meta-analysis of ovarian transcriptome datasets in different cohorts of late-stage HGSOC patients. In vitro cellular models of HGSOC were used for functional studies exploring the role of KLF7 in disease development and progression. Finally, molecular modelling and virtual screening were performed to identify putative KLF7 inhibitors.

RESULTS

Bioinformatic analysis highlighted KLF7 as the most significant prognostic gene, among the 17 family members. Univariate and multivariate analyses identified KLF7 as an unfavourable prognostic marker for overall survival in late-stage TCGA-OV and GSE26712 HGSOC cohorts. Functional in vitro studies demonstrated that KLF7 can play a role as oncogene, driving tumour growth and dissemination. Mechanistic targets of KLF7 included genes involved in epithelial to mesenchymal transition, and in maintaining pluripotency and self-renewal characteristics of cancer stem cells. Finally, in silico analysis provided reliable information for drug-target interaction prediction.

CONCLUSIONS

Results from the present study provide the first evidence for an oncogenic role of KLF7 in HGSOC, suggesting it as a promising prognostic marker and therapeutic target.

Effect of adenosine monophosphate-activated protein kinase-p53-Krüppel-like factor 2a pathway in hyperglycemia-induced cardiac remodeling in adult zebrafish

Aims/Introduction

Diabetic cardiomyopathy is a type of myocardial disease. It causes left ventricular hypertrophy, followed by diastolic and systolic dysfunction, eventually leading to congestive heart failure. However, the underlying mechanism still requires further elucidation.

Materials and Methods

A high‐glucose zebrafish model was constructed by administering streptozocin intraperitoneally to enhance the development of cardiomyopathy and then treated with adenosine monophosphate‐activated protein kinase (AMPK) activator. Cardiac structure and function, and protein and gene expression were then analyzed. Cardiomyocytes (CMs) culture in vitro using lentivirus were used for detection of AMPK, p53 and Krüppel‐like factor 2a (klf2a) gene expression.

Results

In the hyperglycemia group, electrocardiogram findings showed arrhythmia, echocardiography results showed heart enlargement and dysfunction, and many differences, such as increased apoptosis and myocardial fiber loss, were observed. The phospho‐AMPK and klf2a expression were downregulated, and p53 expression was upregulated. Activation of phospho‐AMPK reduced p53 and increased klf2a expression, alleviated apoptosis in CMs and improved cardiac function in the hyperglycemic zebrafish. In vitro knockdown system of AMPK, p53 and klf2a using lentivirus illustrated an increased p53 expression and decreased klf2a expression in CMs by inhibiting AMPK. Repression of p53 and upregulation of klf2a expression were observed, but no changes in the expression of AMPK and its phosphorylated type.

Conclusions

In the model of streptozocin‐induced hyperglycemia zebrafish, the reduction of phosphorylated AMPK increased p53, which led to KLF2a decrease to facilitate apoptosis of CMs, inducing the cardiac remodeling and cardiac dysfunction. These results can be reversed by AMPK activator, which means the AMPK–p53–klf2a pathway might be a potential target for diabetic cardiomyopathy intervention.

Structure-activity relationships of Wee1 inhibitors: A review

Wee1 kinase plays an important role in regulating G2/M checkpoint and S phase, and the inhibition of it will lead to mitotic catastrophe in cancer cells with p53 mutation or deletion. Therefore, the mechanism of Wee1 kinase in cancer treatment and the development of its inhibitors have become a research hotspot. However, although a variety of Wee1 inhibitors with different scaffolds and considerable activity have been successfully identified, so far no one has systematically summarized the structure-activity relationships (SARs) of Wee1 inhibitors. Previous reviews mainly focused on its mechanism and clinical application. To facilitate the rational design and development of Wee1 inhibitors in the future, this paper systematically summarizes its structural types, SARs and binding modes according to the Wee1 inhibitors reported in scientific journals, and also summarizes the regulatory effect of Wee1 kinase on cell cycle and the progress of its inhibitors in clinical application.

Transcriptional network inference and master regulator analysis of the response to ribosome-inactivating proteins in leukemia cells

Gene-regulatory networks reconstruction has become a very popular approach in applied biology to infer and dissect functional interactions of Transcription Factors (TFs) driving a defined phenotypic state, termed as Master Regulators (MRs). In the present work, cutting-edge bioinformatic methods were applied to re-analyze experimental data on leukemia cells (human myelogenous leukemia cell line THP-1 and acute myeloid leukemia MOLM-13 cells) treated for 6 h with two different Ribosome-Inactivating Proteins (RIPs), namely Shiga toxin type 1 (400 ng/mL) produced by Escherichia coli strains and the plant toxin stenodactylin (60 ng/mL), purified from the caudex of Adenia stenodactyla Harms. This analysis allowed us to identify the common early transcriptional response to 28S rRNA damage based on gene-regulatory network inference and Master Regulator Analysis (MRA). Both toxins induce a common response at 6 h which involves inflammatory mediators triggered by AP-1 family transcriptional factors and ATF3 in leukemia cells. We describe for the first time the involvement of MAFF, KLF2 and KLF6 in regulating RIP-induced apoptotic cell death, while receptor-mediated downstream signaling through ANXA1 and TLR4 is suggested for both toxins.

DT-13 induced apoptosis and promoted differentiation of acute myeloid leukemia cells by activating AMPK-KLF2 pathway

Acute myeloid leukemia (AML) is a malignant disease originating from hematopoietic stem cells (HSC). Chemotherapy and/or HSC transplantation is unsatisfactory due to serious side effects, multidrug resistance, and high relapse rate. Thus, alternative strategies are urgently needed to develop more effective therapies. Liriope muscari baily saponins C (DT-13) is a novel compound isolated from Liriope muscari (Decne.) Baily, and exhibited a potent cytotoxicity against several solid tumors. However, the anti-AML activity of DT-13 and the potential mechanisms are still unknown. This study is the first to demonstrate that DT-13 had preferential cytotoxicity against AML cells, and remarkably inhibited proliferation and colony forming ability. Moreover, DT-13 induced the death receptor pathway-dependent apoptosis of HL-60 and Kasumi-1 cells by up-regulating Fas, FasL, DR5 and TRAIL as well as promoted the cleavage of caspase 8, caspase 3 and PARP. Meanwhile, DT-13 induced the differentiation with morphological change related to myeloid differentiation, elevated NBT and α-NAE positive cell rates, differentiation markers CD11b and CD14 as well as level of transcription factors C/EBPα and C/EBPβ. RNA-sequencing analysis revealed that KLF2 may be one of the potential targets regulated by DT-13. Further studies indicated that KLF2 played a critical role in DT-13-induced apoptosis and differentiation. Moreover, activation of AMPK-FOXO was proved to be the upstream of KLF2 pathway that contributed to the induction of apoptosis and differentiation by DT-13. Additionally, restoration of KLF2 by DT-13 was highly correlated with the AMPK-related histone acetylation mechanisms. Finally, DT-13 exhibited an obvious anti-AML effect in NOD/SCID mice with the engraftment of HL-60 cells. Our study suggests that DT-13 may serve as a novel agent for AML by AMPL-KLF2-mediated apoptosis and differentiation.

DGKA Provides Platinum Resistance in Ovarian Cancer Through Activation of c-JUN-WEE1 Signaling

PURPOSE

Although platinum compounds are the first-line treatment for ovarian cancer, the majority of patients relapse and develop resistance to treatment. However, the mechanism underlying resistance is unclear. The goal of our study is to decipher the mechanism by which a metabolic kinase, diacylglycerol kinase alpha (DGKA), confers platinum resistance in ovarian cancer.

EXPERIMENTAL DESIGN

Metabolic kinase RNAi synthetic lethal screening was used to identify a cisplatin resistance driver in ovarian cancer. DGKA variants were used to demonstrate the need for DGKA activity in cisplatin resistance. Phospho-proteomic and genomic screens were performed to identify downstream effectors of DGKA. Therapeutic efficacy of targeting DGKA was confirmed and clinical relevance of DGKA signaling was validated using ovarian cancer patient-derived tumors that had different responses to platinum-based therapy.

RESULTS

We found that platinum resistance was mediated by DGKA and its product, phosphatidic acid (PA), in ovarian cancer. Proteomic and genomic screens revealed that DGKA activates the transcription factor c-JUN and consequently enhances expression of a cell-cycle regulator, WEE1. Mechanistically, PA facilitates c-JUN N-terminal kinase recruitment to c-JUN and its nuclear localization, leading to c-JUN activation upon cisplatin exposure. Pharmacologic inhibition of DGKA sensitized ovarian cancer cells to cisplatin treatment and DGKA-c-JUN-WEE1 signaling positively correlated with platinum resistance in tumors derived from patients with ovarian cancer.

CONCLUSIONS

Our study demonstrates how the DGKA-derived lipid messenger, PA, contributes to cisplatin resistance by intertwining with kinase and transcription networks, and provides preclinical evidence for targeting DGKA as a new strategy in ovarian cancer treatment to battle cisplatin resistance.

WEE1 kinase limits CDK activities to safeguard DNA replication and mitotic entry

Precise execution of the cell division cycle is vital for all organisms. The Cyclin dependent kinases (CDKs) are the main cell cycle drivers, however, their activities must be precisely fine-tuned to ensure orderly cell cycle progression. A major regulatory axis is guarded by WEE1 kinase, which directly phosphorylates and inhibits CDK1 and CDK2. The role of WEE1 in the G2/M cell-cycle phase has been thoroughly investigated, and it is a focal point of multiple clinical trials targeting a variety of cancers in combination with DNA-damaging chemotherapeutic agents. However, the emerging role of WEE1 in S phase has so far largely been neglected. Here, we review how WEE1 regulates cell-cycle progression highlighting the importance of this kinase for proper S phase. We discuss how its function is modulated throughout different cell-cycle stages and provide an overview of how WEE1 levels are regulated. Furthermore, we outline recent clinical trials targeting WEE1 and elaborate on the mechanisms behind the anticancer efficacy of WEE1 inhibition. Finally, we consider novel biomarkers that may benefit WEE1-inhibition approaches in the clinic.

The functions and regulation of Smurfs in cancers

Smad ubiquitination regulatory factor 1 (Smurf1) and Smurf2 are HECT-type E3 ubiquitin ligases, and both Smurfs were initially identified to regulate Smad protein stability in the TGF-β/BMP signaling pathway. In recent years, Smurfs have exhibited E3 ligase-dependent and -independent activities in various kinds of cells. Smurfs act as either potent tumor promoters or tumor suppressors in different tumors by regulating biological processes, including metastasis, apoptosis, cell cycle, senescence and genomic stability. The regulation of Smurfs activity and expression has therefore emerged as a hot spot in tumor biology research. Further, the Smurf1- or Smurf2-deficient mice provide more in vivo clues for the functional study of Smurfs in tumorigenesis and development. In this review, we summarize these milestone findings and, in turn, reveal new avenues for the prevention and treatment of cancer by regulating Smurfs.

The Emerging Roles of ATP-Dependent Chromatin Remodeling Complexes in Pancreatic Cancer

Pancreatic cancer is an aggressive cancer with low survival rates. Genetic and epigenetic dysregulation has been associated with the initiation and progression of pancreatic tumors. Multiple studies have pointed to the involvement of aberrant chromatin modifications in driving tumor behavior. ATP-dependent chromatin remodeling complexes regulate chromatin structure and have critical roles in stem cell maintenance, development, and cancer. Frequent mutations and chromosomal aberrations in the genes associated with subunits of the ATP-dependent chromatin remodeling complexes have been detected in different cancer types. In this review, we summarize the current literature on the genomic alterations and mechanistic studies of the ATP-dependent chromatin remodeling complexes in pancreatic cancer. Our review is focused on the four main subfamilies: SWItch/sucrose non-fermentable (SWI/SNF), imitation SWI (ISWI), chromodomain-helicase DNA-binding protein (CHD), and INOsitol-requiring mutant 80 (INO80). Finally, we discuss potential novel treatment options that use small molecules to target these complexes.

Raddeanin A promotes apoptosis and ameliorates 5-fluorouracil resistance in cholangiocarcinoma cells

BACKGROUND

Bile duct cancer is characterized by fast metastasis and invasion and has been regarded as one of the most aggressive tumors due to the absence of effective diagnosis at an early stage. Therefore, it is in the urgent demand to explore novel diagnostic approaches and therapeutic strategies for bile duct cancer to improve patient survival. Raddeanin A (RA) is extracted from the anemone raddeana regel and has been demonstrated to play antitumor roles in various cancers.

AIM

To investigate the effects of RA treatment on bile duct cancer cells.

METHODS

In this study, four cholangiocarcinoma cell lines (RBE, LIPF155C, LIPF178C, and LICCF) treated with RA were used to test the cell viability. The RA-associated cell functional analysis, 5-fluorouracil (5-Fu) effectiveness as well as cell cycle- and apoptosis-related protein expression were investigated.

RESULTS

RA reduced cell viability in a dose-dependent pattern in four cell lines, and the migration and colony formation abilities were also impaired by RA in RBE and LIPF155C cell lines. RA sensitized cell lines to 5-Fu treatment and enhanced the effects of 5-Fu in cholangiocarcinoma. Also, RA decreased protein expression of Wee1, while the combinational effect of RA and 5-Fu decreased protein expressions of cyclooxygenase-2, B cell lymphoma 2, and Wee1 but increased protein levels of Bax, cyclin D1, and cyclin E.

CONCLUSION

Taken together, the results suggest that RA acts as an anti-cancer agent and enhancer of 5-Fu in bile duct cancer cells via regulating multiple cell cycle and apoptosis-related proteins. This finding provides novel clues to exploring a novel antitumor drug for bile duct cancer.

Enhancement of chemosensitivity by WEE1 inhibition in EGFR-TKIs resistant non-small cell lung cancer

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is the first-line treatment in non-resectable non-small lung cancer (NSCLC) with EGFR mutation. However, EGFR-TIKs resistance would inevitably develop within 9-14 months after treatment. And, chemotherapy is the main treatment for EGFR-TKIs resistant patients. WEE1 kinase, a G2/M checkpoint regulator, was recently considered as a putative biomarker for the platinum-based chemo-response. The aim of this study is to clarify the relationship between WEE1 kinase and chemosensitivity in EGFR-TKIs resistant NSCLC. WEE1 expression was tested in EGFR-TKIs resistant cell lines (H1299, PC9/G2) and patients' specimens by western blot, qPCR and immunohistochemistry (IHC). In in vitro experiment, WEE1 expression was higher in EGFR-TKIs resistant than EGFR-TKIs sensitive cell lines and was gradually increased following cisplatin or gemcitabine treatment with the enrichment of G2/M cell cycle phase. And, for patients with acquired Icotinib/Gefitinib resistance, 58.4% (7/12) had increased WEE1 expression compared to its initial expression level. In order to explore the impact of WEE1 on chemo-response, WEE1 knockdown was conducted in EGFR-TKIs resistant H1299 and PC9/G2 cells. MTT and colony formation assay showed that the efficacy of cisplatin and gemcitabine was enhanced in the two cell lines after WEE1 knockdown. And, the IC50 value of cisplatin decreased from 8.64 μg/ml to 3.10 μg/ml or 2.38 μg/ml in H1299 and from 3.66 μg/ml to 0.97 μg/ml or 1.18 μg/ml in PC9/G2 after WEE1 knockdown with two specific shRNAs. This study revealed that WEE1 expression was increased after EGFR-TKIs resistance, and WEE1 knockdown could enhance chemosensitivity in EGFR-TKIs resistant NSCLC. It is suggested the combination of WEE1 inhibitor and chemotherapy might improve the clinical outcome of NSCLC patients with acquired EGFR-TKIs resistance.

C/EBPβ Is a Transcriptional Regulator of Wee1 at the G₂/M Phase of the Cell Cycle

The CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor that regulates cellular proliferation, differentiation, apoptosis and tumorigenesis. Although the pro-oncogenic roles of C/EBPβ have been implicated in various human cancers, how it contributes to tumorigenesis or tumor progression has not been determined. Immunohistochemistry with human non-small cell lung cancer (NSCLC) tissues revealed that higher levels of C/EBPβ protein were expressed compared to normal lung tissues. Knockdown of C/EBPβ by siRNA reduced the proliferative capacity of NSCLC cells by delaying the G₂/M transition in the cell cycle. In C/EBPβ-knockdown cells, a prolonged increase in phosphorylation of cyclin dependent kinase 1 at tyrosine 15 (Y15-pCDK1) was displayed with simultaneously increased Wee1 and decreased Cdc25B expression. Chromatin immunoprecipitation (ChIP) analysis showed that C/EBPβ bound to distal promoter regions of WEE1 and repressed WEE1 transcription through its interaction with histone deacetylase 2. Treatment of C/EBPβ-knockdown cells with a Wee1 inhibitor induced a decrease in Y15-pCDK1 and recovered cells from G₂/M arrest. In the xenograft tumors, the depletion of C/EBPβ significantly reduced tumor growth. Taken together, these results indicate that Wee1 is a novel transcription target of C/EBPβ that is required for the G₂/M phase of cell cycle progression, ultimately regulating proliferation of NSCLC cells.

KLF2 Inhibits the Migration and Invasion of Prostate Cancer Cells by Downregulating MMP2

KLF2, a member of the Kruppel-like factor (KLF) family, is thought to be a tumor suppressor in many kinds of malignant tumors. Its functions in prostate cancer (PCa) are unknown. This study aimed to explore the role of KLF2 in the migration and invasion of PCa cells. The expression of KLF2 was measured by immunohistochemistry in PCa tissues and in paired non-tumor tissues. KLF2 and MMP2 expression in cells was measured by Western blot and RT-qPCR. Adenoviruses and siRNAs were used in cell function tests to investigate the role of KLF2 in regulating MMP2. Interactions between KLF2 and MMP2 were analyzed by a luciferase activity assay. The present study, for the first time, identified that KLF2 was downregulated both in PCa clinical tissue samples and in cancer cell lines. The overexpression of KLF2 inhibited the migration and invasion of PCa cells via the suppression of MMP2.This study demonstrates that KLF2 might act as a tumor suppressor gene in PCa and that the pharmaceutical upregulation of KLF2 may be a potential approach for treatment.

LncRNA SNHG3 enhances the malignant progress of glioma through silencing KLF2 and p21

As a newly discovered long non-coding RNA, small nucleolar RNA host gene 3 (SHNG3) has been reported to be dysregulated in certain cancers. Nevertheless, the details about clinical values and biological effects of SNHG3 on glioma are still covered. In this paper, we determined the expression level of SNHG3 in glioma tissues and cells and evaluated the effect of SNHG3 expression on the prognosis of glioma patients. The functional assays were applied to define the effects of SNHG3 on the biological behaviors in glioma including cell proliferation, cell cycle, and apoptosis. It was revealed that SNHG3 was much more enriched in glioma tissues and cell lines than in normal ones. Furthermore, gain- or loss-of-function experiments indicated that the up-regulation of SNHG3 promoted cell proliferation, accelerate cell cycle progress, and repressed cell apoptosis. The mechanistic assays disclosed that SNHG3 facilitated the malignant progression of glioma through epigenetically repressing KLF2 and p21 via recruiting enhancer of zeste homolog 2 to the promoter of KLF2 and p21. Generally, it was exposed that SNHG3 might function as an oncogene in glioma and could be explored as a potential prognostic biomarker and therapeutic target for glioma.

miR-106b-responsive gene landscape identifies regulation of Kruppel-like factor family

MicroRNA dysregulation is a common feature of cancer and due to the promiscuity of microRNA binding this can result in a wide array of genes whose expression is altered. miR-106b is an oncomiR overexpressed in cholangiocarcinoma and its upregulation in this and other cancers often leads to repression of anti-tumorigenic targets. The goal of this study was to identify the miR-106b-regulated gene landscape in cholangiocarcinoma cells using a genome-wide, unbiased mRNA analysis. Through RNA-Seq we found 112 mRNAs significantly repressed by miR-106b. The majority of these genes contain the specific miR-106b seed-binding site. We have validated 11 genes from this set at the mRNA level and demonstrated regulation by miR-106b of 7 proteins. Combined analysis of our miR-106b-regulated mRNA data set plus published reports indicate that miR-106b binding is anchored by G:C pairing in and near the seed. Novel targets Kruppel-like factor 2 (KLF2) and KLF6 were verified both at the mRNA and at the protein level. Further investigation showed regulation of four other KLF family members by miR-106b. We have discovered coordinated repression of multiple members of the KLF family by miR-106b that may play a role in cholangiocarcinoma tumor biology.

Lovastatin induced Kruppel like factor 2 (KLF2), Kruppel like factor 6 (KLF6) and Ras homolog family member B (RHOB) genes and preferentially led to viability reduction of Cisplatin-resistant cells

It was reported that statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase that are used to prevent hypercholesterolemia, have antitumor activity in several cancers. In this study, we investigated the cell viability of statins in Cisplatin-resistant HCP4 and PCDP5 cells compared with their parent Hela and PC3 cells, respectively, and found that HCP4 and PCDP5 cells were 37-fold and 18-fold more resistant to Cisplatin but 13-fold and 7-fold more sensitive to Lovastatin by cell proliferation assay. Lovastatin induced the apoptosis of HCP4 cells more rapidly and to greater extent than in Hela cells as assessed by flow cytometry and western blotting analyses. The MVA pathway was not involved in this acquired Cisplatin resistance. To elucidate the mechanism underlying the reduced viability to Lovastatin, we performed cDNA microarray analysis and identified 65 and 54 genes that were induced more than 2-fold by Lovastatin in HCP4 and PCDP5 cells, respectively. Of these, only three genes, KLF2, KLF6, and RHOB, were commonly induced between HCP4 and PCDP5 cells. These mRNAs were strongly induced by Lovastatin with transcriptional regulation in HCP4 cells. Consistent with transcription, the protein expression of RHOB also was induced by Lovastatin. The induction of these genes was associated with cell cycle arrest and apoptosis. Combination treatment with Cisplatin and Lovastatin resulted in an agonistic effect in Hela and PC3 cells and an antagonistic effect in HCP4 and PCDP5 cells. These results suggest that statins might have the potential to overcome Cisplatin resistance as single-agent therapy.

Krüppel-like factor 2 suppresses human gastric tumorigenesis through inhibiting PTEN/AKT signaling

Krüppel-like factors (KLFs) are a large family of DNA-binding transcriptional regulators that affect basic cellular processes such as growth, survival, migration and differentiation and serve a complicated function in cancers. KLF2, one member of the KLF family, is dysregulated in many tumors. However, the specific role of KLF2 in human gastric tumorigenesis is unknown. Here we show that the expression of KLF2 protein was lower in gastric tumors when compared with adjacent normal tissue. Moreover, downregulated KLF2 expression in primary gastric tumor was closely correlated with patients’ survival. Various cell experiments showed that ectopic KLF2 expression suppressed the proliferation, migration and invasion of gastric cancer cells. Moreover, KLF2 overexpression remarkably enhanced cell apoptosis and induced cell cycle arrest. Impaired expression of KLF2 markedly promoted cell growth in vitro and significantly expanded tumor size in vivo. Mechanically, the mRNA and protein level of PTEN was reduced in KLF2 deficient cells and xenograft tumors, suggesting that PTEN/AKT signaling was involved in the gastric tumor inhibitory effect of KLF2. Administration of AKT inhibitor AZD5363 or Insulin-like growth factor-1 (IGF-1) in KLF2 knockdown or ectopic expression cell lines, respectively, substantially reversed the proliferation phenotype. Collectively, our findings provide clinical evidence and a potential mechanism supporting that KLF2 suppresses human gastric tumorigenesis through inhibiting the PTEN/AKT axis.

MicroRNA-145 protects follicular granulosa cells against oxidative stress-induced apoptosis by targeting Krüppel-like factor 4

Oxidative stress-induced follicular granulosa cell (GC) apoptosis plays an essential role in abnormal follicular atresia, which may trigger ovarian dysfunction. To investigate the role of microRNA (miR)-145 in the regulation of GC apoptosis and modulation of the apoptotic pathway in the setting of oxidative stress, we employed an H2O2-induced in vitro model and a 3-nitropropionic acid (NP)-induced in vivo model of ovarian oxidative stress. We demonstrated in vitro that miR-145 expression was significantly down-regulated in KGN cells and mouse granulosa cells (mGCs) treated with H2O2, whereas miR-145 over-expression attenuated H2O2-induced apoptosis in GCs. Moreover, miR-145 protected GCs against H2O2-induced apoptosis by targeting KLF4, which promoted H2O2-induced GC apoptosis via the BAX/BCL-2 pathway. Importantly, decreased miR-145 expression in the in vivo ovarian oxidative stress model promoted apoptosis by up-regulating KLF4 expression, whereas GC-specific miR-145 over-expression attenuated apoptosis by targeting KLF4. In conclusion, miR-145 protects GCs against oxidative stress-induced apoptosis by targeting KLF4.

A novel lncRNA, LL22NC03-N64E9.1, represses KLF2 transcription through binding with EZH2 in colorectal cancer

Long noncoding RNAs (lncRNA) have been implicated in variety human cancer but their mechanisms of function are mainly undocumented. In the present study, we investigated lncRNAs alteration that contributed to colorectal cancer (CRC) by utilizing TCGA RNA sequencing data and other publicly available lncRNAs expression profiling data. Here, We screened out the CRC-associated lncRNA LL22NC03-N64E9.1, a key regulator of CRC development and progression. We also revealed that knockdown of LL22NC03-N64E9.1 inhibited cell proliferation, colony formation, tumorigenicity and apoptosis promotion, both in vitro and in vivo. Mechanistically, LL22NC03-N64E9.1 repressed underlying target gene KLF2 transcription through binding to EZH2. Furthermore, rescue experiments revealed that LL22NC03-N64E9.1 oncogenic function may partially depend on repressing KLF2. Taken together, our results suggested that LL22NC03-N64E9.1 confered an oncogenic function in human CRC and may serve as a candidate prognostic biomarker and target for new therapies in this deadly disease.

KLF2 inhibits cell growth via regulating HIF-1α/Notch-1 signal pathway in human colorectal cancer HCT116 cells

The transcription factor Krüppel-like factor 2 (KLF2) has been shown to function as a tumor suppressor and regulate biological processes of cancer cells, such as cell growth, cell apoptosis and angiogenesis. However, the function and mechanism of KLF2 in colorectal cancer (CRC) is still unknown. In the present study, we show that the expression of KLF2 is diminished in a cohort of CRC cell lines. Also, KLF2 overexpression remarkably inhibits HCT116 and SW480 cell survival and proliferation. Moreover, cell death detection ELISA plus assay showed that KLF2 overexpression increased HCT116 cell proliferation. Caspase-3/7 activity also increased in HCT116 cells transfected with PcDNA3.1-KLF2. Further studies showed that KLF2 significantly suppresses the expression of Notch-1 and is dependent on the decline of the HIF-1α level. Most importantly, silencing Notch-1 expression or HIF-1α level both impair the action of KLF2 overexpression in CRC cells. Collectively, we demonstrated that KLF2 mediates CRC cell biological processes including cell growth and apoptosis via regulating the HIF-1α/Notch-1 signal pathway. These results indicated that KLF2 plays an important role in CRC and provided novel insight on the function of KLF2 in tumor progression.

SP1-induced upregulation of the long noncoding RNA TINCR regulates cell proliferation and apoptosis by affecting KLF2 mRNA stability in gastric cancer

The long noncoding RNA TINCR shows aberrant expression in human squamous carcinomas. However, its expression and function in gastric cancer remain unclear. We report that TINCR is strongly upregulated in human gastric carcinoma (GC), where it was found to contribute to oncogenesis and cancer progression. We also revealed that TINCR overexpression is induced by nuclear transcription factor SP1. Silencing TINCR expression inhibited cell proliferation, colony formation, tumorigenicity and apoptosis promotion, whereas TINCR overexpression promoted cell growth, as documented in the SGC7901 and BGC823 cell lines. Mechanistic analyses indicated that TINCR could bind to STAU1 (staufen1) protein, and influence KLF2 mRNA stability and expression, then KLF2 regulated cyclin-dependent kinase genes CDKN1A/P21 and CDKN2B/P15 transcription and expression, thereby affecting the proliferation and apoptosis of GC cells. Together, our findings suggest that TINCR contributes to the oncogenic potential of GC and may constitute a potential therapeutic target in this disease.

Kruppel-like factor 2 suppresses mammary carcinoma growth by regulating retinoic acid signaling

The transcription factor Kruppel-like factor 2 (KLF2) displays anticarcinogenic activities but the mechanism that underlies this activity is unknown. We show here that KLF2 is markedly downregulated in human breast cancers and that its expression positively correlates with breast cancer patient survival. We show further that KLF2 suppresses tumor development by controlling the transcriptional activity of the vitamin A metabolite retinoic acid (RA). RA regulates gene transcription by activating two types of nuclear receptors: RA receptors (RARs), which inhibit tumor development, and peroxisome proliferator-activated receptor β/δ (PPARβ/δ), which promotes tumorigenesis. The partitioning of RA between these receptors is regulated by two carrier proteins: cellular retinoic acid-binding protein 2 (CRABP2), which delivers RA to RARs, and fatty acid-binding protein 5 (FABP5), which shuttles ligands to PPARβ/δ. We show that KLF2 induces the expression of CRABP2 and RARγ and inhibits the expression FABP5 and PPARβ/δ thereby shifting RA signaling from the pro-carcinogenic FABP5/PPARβ/δ to the growth-suppressing CRABP2/RAR path. The data thus reveal that KLF2 suppresses tumor growth by controlling the transcriptional activities of RA.

Effect of proton and gamma irradiation on human lung carcinoma cells: Gene expression, cell cycle, cell death, epithelial-mesenchymal transition and cancer-stem cell trait as biological end points

Proton beam therapy is a cutting edge modality over conventional gamma radiotherapy because of its physical dose deposition advantage. However, not much is known about its biological effects vis-a-vis gamma irradiation. Here we investigated the effect of proton- and gamma- irradiation on cell cycle, death, epithelial-mesenchymal transition (EMT) and "stemness" in human non-small cell lung carcinoma cells (A549). Proton beam (3MeV) was two times more cytotoxic than gamma radiation and induced higher and longer cell cycle arrest. At equivalent doses, numbers of genes responsive to proton irradiation were ten times higher than those responsive to gamma irradiation. At equitoxic doses, the proton-irradiated cells had reduced cell adhesion and migration ability as compared to the gamma-irradiated cells. It was also more effective in reducing population of Cancer Stem Cell (CSC) like cells as revealed by aldehyde dehydrogenase activity and surface phenotyping by CD44(+), a CSC marker. These results can have significant implications for proton therapy in the context of suppression of molecular and cellular processes that are fundamental to tumor expansion.

WEE1 kinase polymorphism as a predictive biomarker for efficacy of platinum-gemcitabine doublet chemotherapy in advanced non-small cell lung cancer patients

DNA-damaging agents are commonly used for first-line chemotherapy of advanced non-small cell lung cancer (NSCLC). As a G2/M checkpoint kinase, Wee1 can phosphorylate CDC2-tyr15 and induce G2/M cell cycle arrest in response to DNA damage. The correlation of WEE1 polymorphisms to the efficacy of chemotherapy was tested in 663 advanced NSCLC patients. WEE1 rs3910384 genotype correlated to overall survival (OS) and progress-free survival (PFS) of NSCLC patients treated with platinum-based chemotherapy. Sub-group analysis revealed that rs3910384 was particularly associated with the efficacy of doublet chemotherapy combining two DNA-damaging agents, i.e. platinum and gemcitabine. NSCLC patients with the WEE1 rs3910384 G/G homozygote genotype showed 13.5 months extended OS, 3.2 months extended PFS, and a 274% relative increase in their 3-year survival rate (from 7.4% to 27.7%) compared to the A/A+A/G genotype after treatment with platinum-gemcitabine regimen. This finding was reproduced in the validation cohort. We utilized a luciferase reporter assay and Electrophoretic Mobility Shift Assay (EMSA) to demonstrate that rs3910384-linked WEE1 promoter haplotype can mediate allele-specific transcriptional binding and WEE1 expression in DNA damage response. In conclusion, the WEE1 rs3910384 G/G homozygote genotype can be used as a selective biomarker for NSCLC patients to indicate treatment with platinum and gemcitabine regimen.

The Krüppel-like factors in female reproductive system pathologies

Female reproductive tract pathologies arise largely from dysregulation of estrogen and progesterone receptor signaling, leading to aberrant cell proliferation, survival, and differentiation. The signaling pathways orchestrated by these nuclear receptors are complex, require the participation of many nuclear proteins serving as key binding partners or targets, and involve a range of paracrine and autocrine regulatory circuits. The members of the Krüppel-like factor (KLF) family of transcription factors are ubiquitously expressed in reproductive tissues and have been increasingly implicated as critical co-regulators and integrators of steroid hormone actions. Herein, we explore the involvement of KLF family members in uterine pathology, describe their currently known molecular mechanisms, and discuss their potential as targets for therapeutic intervention.

Chk1 and Wee1 control genotoxic-stress induced G2-M arrest in melanoma cells

In the present report, the role of ATR-Chk1-Wee1 and ATM-Chk2-p53-p21 pathways in stress-induced cell cycle control is analysed in melanoma cells. Treatment of p53 wild-type melanoma cells with the genotoxic agent doxorubicin induces G2-M arrest, inhibitory phosphorylation of cell cycle kinase Cdc2 (CDK1) and enhanced expression of p53/p21. Wee1 inhibition under doxorubicin pulse-treatment reduces G2-M arrest and induces apoptosis. Inhibition of upstream kinase Chk1 under doxorubicin treatment almost completely abolishes stress-induced G2-M arrest and induces enhanced apoptosis. Interestingly, Chk1 inhibition alone even further increases apoptosis. While Chk1 inhibition alone almost completely abolishes G0-G1 arrest, combined treatment with doxorubicin re-establishes G0-G1 arrest. Moreover, Chk1 inhibition alone induces only a slight p53/p21 induction, while a strong induction of both proteins is observed by the combination with doxorubicin. These findings are suggestive for a particular role of p53/p21 in G0-G1, and Chk1 in G0-G1 and G2-M arrest. In line with this, the p53-mutant SK-Mel-28 melanoma cells do not mount a significant G0-G1 arrest under combined doxorubicin and Chk1 inhibitor treatment but rather show extensive apoptosis. Moreover, knockdown of p21 dramatically reduces stress-induced G0-G1 arrest under doxorubicin and Chk1 inhibitor treatment accompanied by massive DNA damage and apoptosis induction. Treatment of melanoma cells with an inhibitor of Chk2 upstream kinase ATM and doxorubicin almost completely abolishes G0-G1 arrest. Taken together, both Chk1 and Wee1 are mediators of G2-M arrest, while p53, p21 and Chk1 are mediators of G0-G1 arrest in melanoma cells. Combined treatment with chemotherapeutic agents such as doxorubicin and Chk1 inhibitors may help to overcome apoptosis resistance of p53-proficient melanoma cells. But treatment with Chk1 inhibitor alone may even be more efficient.

Long noncoding RNA ANRIL promotes non-small cell lung cancer cell proliferation and inhibits apoptosis by silencing KLF2 and P21 expression

Recent evidence highlights long noncoding RNAs (lncRNA) as crucial regulators of cancer biology that contribute to essential cancer cell functions such as cell proliferation, apoptosis, and metastasis. In non-small cell lung cancer (NSCLC), several lncRNAs' expressions are misregulated and have been nominated as critical actors in NSCLC tumorigenesis. LncRNA ANRIL was first found to be required for the PRC2 recruitment to and silencing of p15(INK4B), the expression of which is induced by the ATM-E2F1 signaling pathway. Our previous study showed that ANRIL was significantly upregulated in gastric cancer, and it could promote cell proliferation and inhibit cell apoptosis by silencing of miR99a and miR449a transcription. However, its clinical significance and potential role in NSCLC is still not documented. In this study, we reported that ANRIL expression was increased in NSCLC tissues, and its expression level was significantly correlated with tumor-node-metastasis stages and tumor size. Moreover, patients with high levels of ANRIL expression had a relatively poor prognosis. In addition, taking advantage of loss-of-function experiments in NSCLC cells, we found that knockdown of ANRIL expression could impair cell proliferation and induce cell apoptosis both in vitro and vivo. Furthermore, we uncover that ANRIL could not repress p15 expression in PC9 cells, but through silencing of KLF2 and P21 transcription. Thus, we conclusively demonstrate that lncRNA ANRIL plays a key role in NSCLC development by associating its expression with survival in patients with NSCLC, providing novel insights on the function of lncRNA-driven tumorigenesis.

The chromatin remodeling factor CHD5 is a transcriptional repressor of WEE1

Loss of the chromatin remodeling ATPase CHD5 has been linked to the progression of neuroblastoma tumors, yet the underlying mechanisms behind the tumor suppressor role of CHD5 are unknown. In this study, we purified the human CHD5 complex and found that CHD5 is a component of the full NuRD transcriptional repressor complex, which also contains methyl-CpG binding proteins and histone deacetylases. The CHD5/NuRD complex appears mutually exclusive with the related CHD4/NuRD complex as overexpression of CHD5 results in loss of the CHD4 protein in cells. Following a search for genes that are regulated by CHD5 in neuroblastoma cells, we found that CHD5 binds to and represses the G2/M checkpoint gene WEE1. Reintroduction of CHD5 into neuroblastoma cells represses WEE1 expression, demonstrating that CHD5 can function as a repressor in cells. A catalytically inactive mutant version of CHD5 is able to associate with a NuRD cofactor but fails to repress transcription. Our study shows that CHD5 is a NuRD-associated transcriptional repressor and identifies WEE1 as one of the CHD5-regulated genes that may link CHD5 to tumor suppression.

MicroRNA-497 increases apoptosis in MYCN amplified neuroblastoma cells by targeting the key cell cycle regulator WEE1

Background

Neuroblastoma is responsible for 15% of all childhood cancer deaths. Despite advances in treatment and disease management, the overall 5-year survival rates remain poor in high-risk disease (25-40%). MiR-497 was previously identified by our laboratory as a member of a miRNA expression signature, predictive of neuroblastoma patient survival and has been reported as a tumor suppressor in a variety of other cancers. WEE1, a tyrosine kinase regulator of the cell cycle and predicted target of miR-497, has emerged as an oncogene in several cancer types and therefore represents an attractive potential target for novel therapy approaches in high-risk neuroblastoma. Our aim was to investigate the potential tumor suppressive role of miR-497 in high-risk neuroblastoma.

Methods

Expression levels of miR-497 and WEE1 in tissues and cells were determined using RT-PCR. The effect of miR-497 and siWEE1 on cell viability was evaluated using MTS assays, apoptosis levels were determined using FACS analysis of Annexin V/PI stained cells, and target protein expression was determined using western blot. Luciferase reporter plasmids were constructed to confirm direct targeting. Results were reported as mean±S.E.M and differences were tested for significance using 2-tailed Students t-test.

Results

We determined that miR-497 expression was significantly lower in high-risk MYCN amplified (MNA) tumors and that low miR-497 expression was associated with worse EFS and OS in our cohort. Over-expression of miR-497 reduced cell viability and increased apoptosis in MNA cells. We identified WEE1 as a novel target for miR-497 in neuroblastoma. Furthermore, our analysis showed that high WEE1 levels are significantly associated with poor EFS and OS in neuroblastoma and that siRNA knockdown of WEE1 in MNA cell lines results in significant levels of apoptosis, supporting an oncogenic role of WEE1 in neuroblastoma. Cisplatin (CDDP) treatment of both miR-497 over-expressing cells and WEE1 inhibited cells, resulted in a significant increase in apoptosis in MNA cells, describing a synergistic effect and therefore a potential therapeutic for high-risk neuroblastoma.

Conclusion

Our study’s results are consistent with miR-497 being a candidate tumor suppressor in neuroblastoma, through the direct targeting of WEE1. These findings re-enforce the proposal of WEE1 as a therapeutic target in neuroblastoma.

Regulation of cell cycle checkpoint kinase WEE1 by miR-195 in malignant melanoma

WEE1 kinase has been described as a major gate keeper at the G2 cell cycle checkpoint and to be involved in tumour progression in different malignant tumours. Here we analysed the expression levels of WEE1 in a series of melanoma patient samples and melanoma cell lines using immunoblotting, quantitative real-time PCR and immunohistochemistry. WEE1 expression was significantly downregulated in patient samples of metastatic origin as compared with primary melanomas and in melanoma cell lines of high aggressiveness as compared with cell lines of low aggressiveness. Moreover, there was an inverse correlation between the expression of WEE1 and WEE1-targeting microRNA miR-195. Further analyses showed that transfection of melanoma cell lines with miR-195 indeed reduced WEE1 mRNA and protein expression in these cells. Reporter gene analysis confirmed direct targeting of the WEE1 3' untranslated region (3'UTR) by miR-195. Overexpression of miR-195 in SK-Mel-28 melanoma cells was accompanied by WEE1 reduction and significantly reduced stress-induced G2-M cell cycle arrest, which could be restored by stable overexpression of WEE1. Moreover, miR-195 overexpression and WEE1 knockdown, respectively, increased melanoma cell proliferation. miR-195 overexpression also enhanced migration and invasiveness of melanoma cells. Taken together, the present study shows that WEE1 expression in malignant melanoma is directly regulated by miR-195. miR-195-mediated downregulation of WEE1 in metastatic lesions may help to overcome cell cycle arrest under stress conditions in the local tissue microenvironment to allow unrestricted growth of tumour cells.

Mouse Wee1 gene is repressed by Krüppel-like factor 3 (KLF3) via interaction with multiple upstream elements

Wee1 protein kinase represses CDK1 required for G(2)/M transition. The mouse wee1 promoter contains multiple CACCC-boxes between -306 and +1 that can bind to Krüppel-like factor 3 (KLF3) transcriptional repressor. We found that increasing amounts of intracellular KLF3 decreased the amount of wee1 mRNA. A promoter reporter assay demonstrated that wee1 promoter activity was repressed by KLF3 overexpression. Elimination of the first and fourth CACCC-boxes suppressed KLF3-governed transcriptional repression. A gel-shift assay demonstrated that KLF3 binds to the first, third, and fourth CACCC-boxes with various strengths. Moreover, KLF3 was suggested to interact with the wee1 regulatory region in a physiological condition. Therefore, we concluded that KLF3 is a transcriptional repressor for wee1 gene. In a previous study, we demonstrated that TBP-like protein (TLP) inhibits wee1 promoter function. In this study, we found that the chromosomal wee1 gene is also down-regulated by KLF3. Since KLF3-repressed wee1 promoter function was further inhibited by TLP overexpression regardless of the inhibition degree of KLF3, we propose that TLP and KLF3 repress wee1 promoter independently.

Silencing of Kruppel-like factor 2 by the histone methyltransferase EZH2 in human cancer

The Kruppel-like factor (KLF) proteins are multitasked transcriptional regulators with an expanding tumor suppressor function. KLF2 is one of the prominent members of the family because of its diminished expression in malignancies and its growth-inhibitory, pro-apoptotic and anti-angiogenic roles. In this study, we show that epigenetic silencing of KLF2 occurs in cancer cells through direct transcriptional repression mediated by the Polycomb group protein Enhancer of Zeste Homolog 2 (EZH2). Binding of EZH2 to the 5'-end of KLF2 is also associated with a gain of trimethylated lysine 27 histone H3 and a depletion of phosphorylated serine 2 of RNA polymerase. Upon depletion of EZH2 by RNA interference, short hairpin RNA or use of the small molecule 3-Deazaneplanocin A, the expression of KLF2 was restored. The transfection of KLF2 in cells with EZH2-associated silencing showed a significant anti-tumoral effect, both in culture and in xenografted nude mice. In this last setting, KLF2 transfection was also associated with decreased dissemination and lower mortality rate. In EZH2-depleted cells, which characteristically have lower tumorigenicity, the induction of KLF2 depletion 'rescued' partially the oncogenic phenotype, suggesting that KLF2 repression has an important role in EZH2 oncogenesis. Most importantly, the translation of the described results to human primary samples demonstrated that patients with prostate or breast tumors with low levels of KLF2 and high expression of EZH2 had a shorter overall survival.

The BioAssay network and its implications to future therapeutic discovery

Background

Despite intense investment growth and technology development, there is an observed bottleneck in drug discovery and development over the past decade. NIH started the Molecular Libraries Initiative (MLI) in 2003 to enlarge the pool for potential drug targets, especially from the “undruggable” part of human genome, and potential drug candidates from much broader types of drug-like small molecules. All results are being made publicly available in a web portal called PubChem.

Results

In this paper we construct a network from bioassay data in PubChem, apply network biology concepts to characterize this bioassay network, integrate information from multiple biological databases (e.g. DrugBank, OMIM, and UniHI), and systematically analyze the potential of bioassay targets being new drug targets in the context of complex biological networks. We propose a model to quantitatively prioritize this druggability of bioassay targets, and literature evidence was found to confirm our prioritization of bioassay targets at a roughly 70% accuracy.

Conclusions

Our analysis provide some measures of the value of the MLI data as a resource for both basic chemical biology research and future therapeutic discovery.

Relationship between WEE 1 and hepatocellular carcinoma

AIM: To investigate the expression of WEE 1 in hepatocellular carcinoma (HCC) and to analyze its relationship with clinicopathological characteristics of HCC.

METHODS: Twenty-three normal human liver tissue specimens, 20 cirrhosis specimens, and 42 HCC specimens were used in this study. Reverse transcriptional-polymerase chain reaction (RT-PCR) was used to measure the expression of WEE 1 mRNA in the above tissue specimens, while Western blot and immunohistochemistry were used to detect the expression of WEE 1 protein. The relationship between WEE 1 expression and clinicopathological characteristics of HCC was analyzed.

RESULTS: The positive rates of Wee 1 mRNA expression in normal liver tissue, cirrhosis and HCC were 21.7%, 55% and 90.5%, respectively, with a significant difference among the three groups (P < 0.01). The positive rates of Wee 1 protein expression as revealed by Western blot and immunohistochemistry in the above three groups were 13.04%/17.4%, 40%/60% and 78.6%/83.3%, respectively, with significant differences among the three groups (both P < 0.01). Up-regulated expression of WEE 1 was significantly correlated with tumor differentiation and pathological grade in HCC (χ² = 17.454, P < 0.01; χ² = 14.559, P < 0.01).

CONCLUSION: WEE 1 expression was significantly up-regulated in HCC. High expression of WEE 1 may be closely related with tumor differentiation and pathological grade in HCC.

WEE1 kinase targeting combined with DNA-damaging cancer therapy catalyzes mitotic catastrophe

WEE1 kinase is a key molecule in maintaining G₂-cell-cycle checkpoint arrest for premitotic DNA repair. Whereas normal cells repair damaged DNA during G₁-arrest, cancer cells often have a deficient G₁-arrest and largely depend on G₂-arrest. The molecular switch for the G₂-M transition is held by WEE1 and is pushed forward by CDC25. WEE1 is overexpressed in various cancer types, including glioblastoma and breast cancer. Preclinical studies with cancer cell lines and animal models showed decreased cancer cell viability, reduced tumor burden, and improved survival after WEE1 inhibition by siRNA or small molecule inhibitors, which is enhanced by combination with conventional DNA-damaging therapy, such as radiotherapy and/or cytostatics. Mitotic catastrophe results from premature entry into mitosis with unrepaired lethal DNA damage. As such, cancer cells become sensitized to conventional therapy by WEE1 inhibition, in particular those with insufficient G₁-arrest due to deficient p53 signaling, like glioblastoma cells. One WEE1 inhibitor has now reached clinical phase I studies. Dose-limiting toxicity consisted of hematologic events, nausea and/or vomiting, and fatigue. The combination of DNA-damaging cancer therapy with WEE1 inhibition seems to be a rational approach to push cancer cells in mitotic catastrophe. Its safety and efficacy are being evaluated in clinical studies.

Smurf1 ubiquitin ligase targets Kruppel-like factor KLF2 for ubiquitination and degradation in human lung cancer H1299 cells

Krüppel-like factor 2 (KLF2) has been demonstrated to be essential for normal lung development, erythroid differentiation, T-cell differentiation, migration and homing. However, the mechanisms underlying the regulation of KLF2, in particular its responsible E3 ligase is still unclear. Here we show that the homologous to E6AP carboxyl terminus (HECT)-type ubiquitin ligase Smad ubiquitination regulatory factor 1 (Smurf1) interacts with and targets KLF2 for poly-ubiquitination and proteasomal degradation specifically in lung cancer H1299 cells. The catalytic ligase activity of Smurf1 is required for it to regulate KLF2. Consequently, Smurf1 represses the transcriptional factor activity of KLF2 and regulates the expression its downstream genes such as CD62L and Wee1. This study provided the first evidence that Smurf1 functions as an E3 ligase to promote the ubiquitination and proteasomal degradation of KLF2.

Biological effects of induced MYCN hyper-expression in MYCN-amplified neuroblastomas

Neuroblastoma is a childhood malignancy of the sympathetic nervous system. The tumor exhibits two different phenotypes: favorable and unfavorable. MYCN amplification is associated with rapid tumor progression and the worst neuroblastoma disease outcome. We have previously reported that inhibitors of histone deacetylase (HDAC) and proteasome enhance favorable neuroblastoma gene expression in neuroblastoma cell lines and inhibit growth of these cells. In this study, we investigated the effect of trichostatin A or TSA (an HDAC inhibitor), and epoxomycin (a proteasome inhibitor) on MYCN and p53 expression in MYCN-amplified neuroblastoma cells. It was found that TSA down-regulated MYCN expression, but Epoxomycin and the TSA/Epoxomycin combination led to MYCN hyper-expression in MYCN-amplified neuroblastoma cell lines. Despite their contrasting effects on MYCN expression, TSA and Epoxomycin caused growth suppression and cell death of the MYCN-amplified cell lines examined. Consistent with these data, forced hyper-expression of MYCN in MYCN-amplified IMR5 cells via transfection resulted in growth suppression and the increased expression of several genes known to suppress growth or induce cell death. Furthermore, Epoxomycin as a single agent and its combination with TSA enhance p53 expression in the MYCN-amplified neuroblastoma cell lines. Unexpectedly, co-transfection of TP53 and MYCN in IMR5 cells resulted in high p53 expression but a reduction of MYCN expression. Together our data suggest that either down regulation or hyper-expression of MYCN results in growth inhibition and/or apoptosis of MYCN-amplified neuroblastoma cells. In addition, elevated p53 expression has a suppressive effect on MYCN expression in these cells.

Kruppel-like factor 2 is required for trafficking but not quiescence in postactivated T cells

The transcription factor Kruppel-like factor 2 (KLF2) was proposed to regulate genes involved in cell cycle entry and T cell trafficking; however, the physiological role of its expression in postactivated T cells is not well defined. Previous studies suggested that the cytokines IL-2 and IL-15 differentially regulate KLF2 re-expression in postactivation T cells and that these cytokines also influence effector versus memory T cell differentiation. Using conditional and inducible KLF2-knockout model systems, we tested the specific role of KLF2 expression in activated CD8(+) T cells cultured with these cytokines. KLF2 was required for effective transcription of sphingosine-1-phosphate receptor-1 (S1P(1)) and CD62L in postactivation T cells. However, although different cytokines dramatically altered the expression of cell-cycle-related genes, endogenous KLF2 had a minimal impact. Correspondingly, KLF2-deficient T cells showed dysregulated trafficking but not altered proliferative characteristics following in vivo responses to Ag. Thus, our data help to define KLF2-dependent and -independent aspects of activated CD8(+) T cell differentiation and argue against a physiological role in cell cycle regulation.

Distinct DNA methylation profiles in ovarian serous neoplasms and their implications in ovarian carcinogenesis

OBJECTIVE

The purpose of this study was to analyze DNA methylation profiles among different types of ovarian serous neoplasm, which is a task that has not been performed.

STUDY DESIGN

The Illumina beads array (Illumina Inc, San Diego, CA) was used to profile DNA methylation in enriched tumor cells that had been isolated from 75 benign and malignant serous tumor tissues and 6 tumor-associated stromal cell cultures.

RESULTS

We found significantly fewer hypermethylated genes in high-grade serous carcinomas than in low-grade serous carcinoma and borderline tumors, which in turn had fewer hypermethylated genes than serous cystadenoma. Unsupervised analysis identified that serous cystadenoma, serous borderline tumor, and low-grade serous carcinomas tightly clustered together and were clearly different from high-grade serous carcinomas. We also performed supervised analysis to identify differentially methylated genes that may contribute to group separation.

CONCLUSION

The findings support the view that low-grade and high-grade serous carcinomas are distinctly different with low-grade, but not high-grade, serous carcinomas that are related to serous borderline tumor and cystadenoma.