Valproic acid induces Notch1 signaling in small cell lung cancer cells

Histone deacetylase inhibitors VPA and WT161 ameliorate the pathological features and cognitive impairments of the APP/PS1 Alzheimer's disease mouse model by regulating the expression of APP secretases

BACKGROUND

Alzheimer's disease (AD) is a degenerative neurological disorder. Recent studies have indicated that histone deacetylases (HDACs) are among the most prominent epigenetic therapy targets and that HDAC inhibitors have therapeutic effects on AD. Here, we identified sodium valproate (VPA), a pan-HDAC inhibitor, and WT161, a novel HDAC6 selective inhibitor, as potential therapeutic agents for AD. Underlying molecular mechanisms were investigated.

METHODS

A cellular model, N2a-APPswe, was established via lentiviral infection, and the APPswe/PSEN1dE9 transgenic mouse model was employed in the study. LC-MS/MS was applied to quantify the concentration of WT161 in the mouse brain. Western blotting, immunohistochemical staining, thioflavin-S staining and ELISA were applied to detect protein expression in cells, tissues, or serum. RNA interference was utilized to knockdown the expression of specific genes in cells. The cognitive function of mice was assessed via the nest-building test, novel object recognition test and Morris water maze test.

RESULTS

Previous studies have focused mainly on the impact of HDAC inhibitors on histone deacetylase activity. Our study discovered that VPA and WT161 can downregulate the expression of multiple HDACs, such as HDAC1 and HDAC6, in both AD cell and mouse models. Moreover, they also affect the expression of APP and APP secretases (BACE1, PSEN1, ADAM10). RNA interference and subsequent vitamin C induction further confirmed that the expression of APP and APP secretases is indeed regulated by HDAC1 and HDAC6, with the JNK pathway being the intermediate link in this regulatory process. Through the above pathways, VPA and WT161 effectively reduced Aβ deposition in both AD cell and mouse models and significantly improved cognitive function in AD mice.

CONCLUSIONS

In general, we have discovered that the HDAC6-JNK-APP secretases cascade is an important pathway for VPA and WT161 to exert their therapeutic effects on AD. Investigations into the safety and efficacy of VPA and WT161 were also conducted, providing essential preclinical evidence for assessing these two epigenetic drugs for the treatment of AD.

Lycorine inhibits pancreatic cancer cell growth and neovascularization by inducing Notch1 degradation and downregulating key vasculogenic genes

Pancreatic cancer is highly metastatic and lethal with an increasing incidence globally and a 5-year survival rate of only 8%. One of the factors contributing to the high mortality is the lack of effective drugs in the clinical setting. We speculated that effective compounds against pancreatic cancer exist in natural herbs and explored active small molecules among traditional Chinese medicinal herbs. The small molecule lycorine (MW: 323.77) derived from the herb Lycoris radiata inhibited pancreatic cancer cell growth with an IC50 value of 1 μM in a concentration-dependent manner. Lycorine markedly reduced pancreatic cancer cell viability, migration, invasion, neovascularization, and gemcitabine resistance. Additionally, lycorine effectively suppressed tumor growth in mouse xenograft models without obvious toxicity. Pharmacological studies revealed that the levels and half-life of Notch1 oncoprotein in the pancreatic cancer cells Panc-1 and Patu8988 were notably reduced. Moreover, the expression of the key vasculogenic genes Semaphorin 4D (Sema4D) and angiopoietin-2 (Ang-2) were also significantly inhibited by lycorine. Mechanistically, lycorine strongly triggered the degradation of Notch1 oncoprotein through the ubiquitin-proteasome system. In conclusion, lycorine effectively inhibits pancreatic cancer cell growth, migration, invasion, neovascularization, and gemcitabine resistance by inducing degradation of Notch1 oncoprotein and downregulating the key vasculogenic genes Sema4D and Ang-2. Our findings provide a new therapeutic candidate and treatment strategy against pancreatic cancer.

Targeting histone deacetylases for heart diseases

Histone deacetylases (HDACs) are responsible for the deacetylation of lysine residues in histone or non-histone substrates, leading to the regulation of many biological functions, such as gene transcription, translation and remodeling chromatin. Targeting HDACs for drug development is a promising way for human diseases, including cancers and heart diseases. In particular, numerous HDAC inhibitors have revealed potential clinical value for the treatment of cardiac diseases in recent years. In this review, we systematically summarize the therapeutic roles of HDAC inhibitors with different chemotypes on heart diseases. Additionally, we discuss the opportunities and challenges in developing HDAC inhibitors for the treatment of cardiac diseases.

MDK induces temozolomide resistance in glioblastoma by promoting cancer stem-like properties

Glioblastoma (GBM) is the most frequently observed and aggressive type of high-grade malignant glioma. Temozolomide (TMZ) is the primary agent for GBM treatment. However, TMZ resistance remains a major challenge. In this study, we report that MDK is overexpressed in GBM, which leads to enhanced proliferation, apoptosis inhibition, increased invasion and TMZ resistance in GBM cells. It was also determined that MDK could significantly improve the stem-like properties of GBM cells. Mechanistically, MDK enhanced p-JNK through Notch1 and subsequently increased the expression of stemness markers, such as CD133 and Nanog, thereby promoting TMZ resistance. Finally, xenograft experiments and clinical sample analysis also demonstrated that MDK knockdown could significantly inhibit tumor growth in vivo, and the expression of MDK was positively correlated with Notch1, p-JNK and CD133. This study revealed that MDK induces TMZ resistance by improving the stem-like properties of GBM by upregulating the Notch1/p-JNK signaling pathway, which provides a possible target for therapeutic intervention of GBM, especially in TMZ-resistant GBM with high MDK expression.

Signatures of Co-Deregulated Genes and Their Transcriptional Regulators in Lung Cancer

Despite the significant progress made towards comprehending the deregulated signatures in lung cancer, these vary from study to study. We reanalyzed 25 studies from the Gene Expression Omnibus (GEO) to detect and annotate co-deregulated signatures in lung cancer and in single-gene or single-drug perturbation experiments. We aimed to decipher the networks that these co-deregulated genes (co-DEGs) form along with their upstream regulators. Differential expression and upstream regulators were computed using Characteristic Direction and Systems Biology tools, including GEO2Enrichr and X2K. Co-deregulated gene expression profiles were further validated across different molecular and immune subtypes in lung adenocarcinoma (TCGA-LUAD) and lung adenocarcinoma (TCGA-LUSC) datasets, as well as using immunohistochemistry data from the Human Protein Atlas, before being subjected to subsequent GO and KEGG enrichment analysis. The functional alterations of the co-upregulated genes in lung cancer were mostly related to immune response regulating the cell surface signaling pathway, in contrast to the co-downregulated genes, which were related to S-nitrosylation. Networks of hub proteins across the co-DEGs consisted of overlapping TFs (SOX2, MYC, KAT2A) and kinases (MAPK14, CSNK2A1 and CDKs). Furthermore, using Connectivity Map we highlighted putative repurposing drugs, including valproic acid, betonicine and astemizole. Similarly, we analyzed the co-DEG signatures in single-gene and single-drug perturbation experiments in lung cancer cell lines. In summary, we identified critical co-DEGs in lung cancer providing an innovative framework for their potential use in developing personalized therapeutic strategies.

Oxidative stress mediated by the TLR4/NOX2 signalling axis is involved in polystyrene microplastic-induced uterine fibrosis in mice

Microplastics (MPs), as a new environmental pollutant, have received widespread attention worldwide. Uterine fibrosis is one of the main factors of female reproductive disorders. However, it is unclear whether the female reproductive disorders caused by MPs are related to uterine fibrosis. Therefore, in this study, we constructed female mouse models exposed to polystyrene microplastics (PS-MPs). We found that PS-MP exposure resulted in endometrial thinning and severe collagen fibre deposition in female mice. Further mechanistic studies found that PS-MP exposure increased the expression of high mobility group Box 1 (HMGB1) and acetyl-HMGB1, further activating the Toll-like receptor 4/NADPH oxidase 2 (TLR4/NOX2) signalling axis and eventually causing oxidative stress. Afterwards, oxidative stress elicited the activation of Notch and the transforming growth factor β (TGF-β) signalling pathway, leading to increased levels of fibrotic proteins and collagen. Correspondingly, PS-MP treatment upregulated the expression of TLR4 and NOX2 and the level of reactive oxygen species (ROS) and increased the levels of fibrotic protein and collagen in mouse endometrial epithelial cells cultured in vitro. Conversely, inhibition of the TLR4/NOX2 signalling pathway effectively reduced the level of ROS in cells, weakened the upregulation of Notch and TGF-β signalling by PS-MPs, and efficiently reduced the expression of fibrotic and collagen genes. In summary, we demonstrated a new mechanism by which MPs induce uterine fibrosis in mice, that is, by inducing oxidative stress to activate the Notch and TGF-β signalling pathways by triggering the TLR4/NOX2 signalling axis. Targeting TLR4/NOX2 signalling may consequently prove to be an innovative therapeutic option that is effective in alleviating the reproductive toxicity of PS-MPs. Our study sheds new light on the reproductive toxicity of MPs and provides suggestions and references for comparative medicine and clinical medicine.

Low trifloxystrobin-tebuconazole concentrations induce cardiac and developmental toxicity in zebrafish by regulating notch mediated-oxidative stress generation

Trifloxystrobin-tebuconazole (TFS-TBZ) is a novel, broad-spectrum fungicide that has been frequently detected in both the environment and agricultural products. However, its adverse effects on aquatic organisms remain unknown. In this study, the adverse effects of ecologically relevant TFS-TBZ concentrations (i.e., 75.0, 112.5, and 150.0 μg/L) on the heart and development of zebrafish were investigated. TFS-TBZ was found to substantially hinder development, inhibit growth, and cause significant abnormity at higher concentrations. Moreover, TFS-TBZ caused severe pericardial edema, heart loop failure, cardiac linearization, and ultra-slow heartbeat, implying that TFS-TBZ might induce congenital heart disease. TFS-TBZ inhibited Notch signaling and increased the intracellular generation of reactive oxygen species, resulting in decreased myocardial cell proliferation and increased apoptosis. The use of sodium valproate and Gadofullerene illustrated the relevance of the Notch signaling system and oxidative stress. Finally, TFS-TBZ exposure conveys severe developmental toxicity to the zebrafish heart. The underlying mechanism is regulation notch mediated-oxidative stress generation, implying that TFS-TBZ may be potentially hazardous to aquatic organisms in the environment.

Sodium Valproate Is Effective Against Botrytis cinerea Infection of Tomato by Enhancing Histone H3 Acetylation-Directed Gene Transcription and Triggering Tomato Fruit Immune Response

Botrytis cinerea causes gray mold resulting in enormous financial loss. Fungicide resistance of B. cinerea has become a serious issue in food safety and agricultural environmental protection. Sodium valproate (SV) has been used in clinical trials; thus, it is an excellent candidate for fungicide development, considering its safety. However, the antifungal activity remains unclear. SV was effective against B. cinerea by enhancing acetylation of histone H3, including H3K9ac, H3K14ac, and H3K56ac. A transcriptomics analysis revealed that the expression of 1,557 genes changed significantly in response to SV. A pathway enrichment analysis identified 16 significant GO terms, in which molecular functions were mainly involved. In addition, the expression levels of 13 genes involved in B. cinerea virulence and five genes involved in tomato immune response were altered by the SV treatment. These results indicate that SV inhibits B. cinerea by enhancing acetylation of histone H3 and modifying gene transcription. Thus, SV is an effective, safe, potential antifungal agent for control of both pre- and postharvest losses caused by B. cinerea.

Diagnostic value of abnormal chromosome 3p genes in small‑cell lung cancer

The diagnosis of small cell lung carcinoma (SCLC) remains a great challenge. Changes in chromosome 3p (chr3) genes are usually observed in the pathogenesis of lung cancer, which suggests that these chr3 genes may be a diagnostic marker in the early stage of SCLC. The present study explored the diagnostic value of the chr3 gene in SCLC using Bioinformatics. Furthermore, reverse transcription-quantitative PCR (RT-qPCR) was used to reveal the expression patterns of diagnostic biomarkers in human pulmonary alveolar epithelial cells and in the SCLC cell line NCI-H146. A total of 33 differentially expressed (DE) chr3 genes and 1,156 module genes associated with clinical features of patients with SCLC were identified and functional enrichment analysis indicated that all these genes were significantly enriched in cell cycle terms. The area under the receiver operating characteristic curve demonstrated that the overlapping genes of the DE-chr3 and module genes, namely cell division cycle 25 A (CDC25A), FYVE and coiled-coil domain autophagy adaptor 1 (FYCO1) and lipid raft linker 1 (RFTN1), were relatively accurate in distinguishing normal from SCLC samples, and may thus be considered diagnostic biomarkers. CDC25A was overexpressed in SCLC samples, while FYCO1 and RFTN1 were highly expressed in normal samples, as evidenced by the RT-qPCR results. Single-gene gene set enrichment analysis suggested that the diagnostic biomarkers were significantly associated with cell cycle, ATP-binding cassette transporter, immune cell differentiation, immune response and multiple respiratory disease pathways. Furthermore, a total of 141 drugs were predicted by The Comparative Toxicogenomics Database to be able to modulate the expression of the diagnostic biomarkers, of which 8 drugs were shared among the three aforementioned diagnostic biomarkers. The present study identified three novel and powerful diagnostic biomarkers for SCLC based on chr3 genes. Suggestions for the development and selection of drugs for clinical treatment based on diagnostic biomarkers were also provided.

Valproic Acid Initiates Transdifferentiation of the Human Ductal Adenocarcinoma Cell-line Panc-1 Into α-Like Cells

Non-mesenchymal pancreatic cells are a potential source for cell replacement. Their transdifferentiation can be achieved by triggering epigenetic remodeling through e. g. post-translational modification of histones. Valproic acid, a branched-chain saturated fatty acid with histone deacetylase inhibitor activity, was linked to the expression of key transcription factors of pancreatic lineage in epithelial cells and insulin transcription. However, the potential of valproic acid to cause cellular reprogramming is not fully understood. To shed further light on it we employed next-generation RNA sequencing, real-time PCR, and protein analyses by ELISA and western blot, to assess the impact of valproic acid on transcriptome and function of Panc-1-cells. Our results indicate that valproic acid has a significant impact on the cell cycle, cell adhesion, histone H3 acetylation, and metabolic pathways as well as the initiation of epithelial-mesenchymal transition through acetylation of histone H3 resulting in α-cell-like characteristics. We conclude that human epithelial pancreatic cells can be transdifferentiated into cells with endocrine properties through epigenetic regulation by valproic acid favoring an α-cell-like phenotype.

High-Throughput Analysis to Identify Activators of Notch Signaling

The Notch pathway regulates many cellular functions in a context-dependent manner. Depending on the cell type, either the activation or inhibition of Notch signaling can influence many processes such as cellular proliferation, specification, differentiation, and survival. The activation of Notch signaling has been shown to have therapeutic advantages in some cancers, thus having a method to identify Notch-activating compounds is needed. In this chapter we outline a method for high-throughput analysis of potential Notch pathway activators in a pancreatic neuroendocrine tumor cell line as an example. We also include the steps for subsequent validation of results and preclinical testing.

Membrane protein CAR promotes hematopoietic regeneration upon stress

Adult hematopoietic stem cells (HSC) are quiescent most of the time, and how HSC switch from quiescence to proliferation following hematopoietic stress is unclear. Here we demonstrate that upon stress the coxsackievirus and adenovirus receptor CAR (also known as CXADR) is upregulated in HSC and critical for HSC entry into the cell cycle. Wild-type HSC were detected with more rapid repopulation ability than the CAR knockout counterparts. After fluorouracil treatment, CAR knockout HSC had lower levels of Notch1 expression and elevated protein level of Numb, a Notch antagonist. The Notch signaling inhibitor DAPT, dominant negative form of MAML (a transcriptional coactivator of Notch), or dominant negative mutant of LNX2 (an E3 ligase that acts on Numb and binds to CAR), all were capable of abrogating the function of CAR in HSC. We conclude that CAR activates Notch1 signaling by downregulating Numb protein expression to facilitate entry of quiescent HSC into the cell cycle during regeneration.

Notch signaling and efficacy of PD-1/PD-L1 blockade in relapsed small cell lung cancer

Immune checkpoint blockade (ICB) benefits only a small subset of patients with small cell lung cancer (SCLC), yet the mechanisms driving benefit are poorly understood. To identify predictors of clinical benefit to ICB, we performed immunogenomic profiling of tumor samples from patients with relapsed SCLC. Tumors of patients who derive clinical benefit from ICB exhibit cytotoxic T-cell infiltration, high expression of antigen processing and presentation machinery (APM) genes, and low neuroendocrine (NE) differentiation. However, elevated Notch signaling, which positively correlates with low NE differentiation, most significantly predicts clinical benefit to ICB. Activation of Notch signaling in a NE human SCLC cell line induces a low NE phenotype, marked by increased expression of APM genes, demonstrating a mechanistic link between Notch activation, low NE differentiation and increased intrinsic tumor immunity. Our findings suggest Notch signaling as a determinant of response to ICB in SCLC.

Immune checkpoint blockade (ICB) benefits only a small subset of patients with small cell lung cancer (SCLC) and the mechanisms driving benefit are poorly understood. Here, the authors show that elevated Notch signaling predicts clinical benefit in ICB in relapsed SCLC.

Histone Deacetylase Inhibitors in the Treatment of Hepatocellular Carcinoma: Current Evidence and Future Opportunities

Hepatocellular carcinoma (HCC) remains a major health problem worldwide with a continuous increasing prevalence. Despite the introduction of targeted therapies like the multi-kinase inhibitor sorafenib, treatment outcomes are not encouraging. The prognosis of advanced HCC is still dismal, underlying the need for novel effective treatments. Apart from the various risk factors that predispose to the development of HCC, epigenetic factors also play a functional role in tumor genesis. Histone deacetylases (HDACs) are enzymes that remove acetyl groups from histone lysine residues of proteins, such as the core nucleosome histones, in this way not permitting DNA to loosen from the histone octamer and consequently preventing its transcription. Considering that HDAC activity is reported to be up-regulated in HCC, treatment strategies with HDAC inhibitors (HDACIs) showed some promising results. This review focuses on the use of HDACIs as novel anticancer agents and explains the mechanisms of their therapeutic effects in HCC.

The Role of HDACs and HDACi in Cartilage and Osteoarthritis

Epigenetics plays an important role in the pathogenesis and treatment of osteoarthritis (OA). In recent decades, HDAC family members have been associated with OA. This paper aims to describe the different role of HDACs in the pathogenesis of OA through interaction with microRNAs and the regulation of relevant signaling pathways. We found that HDACs are involved in cartilage and chondrocyte development but also play a crucial role in OA. However, the distinct HDAC mechanism in the pathogenesis and treatment of OA require further investigation. Furthermore, HDAC inhibitors (HDACi) can protect cartilage from disease, which may represent a potential therapeutic approach against OA.

Primary infection by Pneumocystis induces Notch-independent Clara cell mucin production in rat distal airways

Clara cells are the main airway secretory cells able to regenerate epithelium in the distal airways through transdifferentiating into goblet cells, a process under negative regulation of the Notch pathway. Pneumocystis is a highly prevalent fungus in humans occurring between 2 and 5 months of age, a period when airways are still developing and respiratory morbidity typically increases. Pneumocystis induces mucus hyperproduction in immunocompetent host airways and whether it can stimulate Clara cells is unknown. Markers of Clara cell secretion and Notch1 activation were investigated in lungs of immunocompetent rats at 40, 60, and 80 days of age during Pneumocystis primary infection with and without Valproic acid (VPA), a Notch inducer. The proportion of rats expressing mucin increased in Pneumocystis-infected rats respect to controls at 60 and 80 days of age. Frequency of distal airways Clara cells was maintained while mRNA levels for the mucin-encoding genes Muc5B and Muc5ac in lung homogenates increased 1.9 and 3.9 times at 60 days of infection (P. = 0.1609 and P. = 0.0001, respectively) and protein levels of the Clara cell marker CC10 decreased in the Pneumocystis-infected rats at 60 and 80 days of age (P. = 0.0118 & P. = 0.0388). CC10 and Muc5b co-localized in distal airway epithelium of Pneumocystis-infected rats at day 60. Co-localization of Muc5b and Ki67 as marker of mitosis in distal airways was not observed suggesting that Muc5b production by Clara cells was independent of mitosis. Notch levels remained similar and no transnucleation of activated Notch associated to Pneumocystis infection was detected. Unexpectedly, mucus was greatly increased at day 80 in Pneumocystis-infected rats receiving VPA suggesting that a Notch-independent mechanism was triggered. Overall, data suggests a Clara to goblet cell transdifferentiation mechanism induced by Pneumocystis and independent of Notch.

Effect of valproic acid on cisplatin-resistant ovarian cancer cell lines

Background and aims: Platinum resistance has been one of the most important problems in the management of ovarian cancer. The effects of various chemotherapeutic agents are limited in patients with platinum resistance. Therefore, developing new anticancer drugs that can improve the effect of currently used cytostatics is critical. The current study investigated the effects of valproic acid (VPA) alone and in combination with cisplatin on ovarian cancer cells. Methods: In this experimental study, the human ovarian cancer cell lines (A2780-S and A2780-CP) were grown in RPMI-1640 medium in appropriate culture conditions. The cells were treated with various concentrations of cisplatin (0.15-400 µg/mL) or VPA (10-2000 µg/mL) and were incubated for 24, 48, and 72 hours. Moreover, A2780 cells were co-treated with different concentrations of cisplatin and VPA for 48 hours. Afterward, cell viability was investigated using MTT assay. GraphPad Prism statistical software was used for the data analysis and ANOVA and Duncan’s test were conducted. Results: A dose- and time-dependent reduction was observed in cell viability following the treatment with cisplatin or VPA. Moreover, cotreatment of the A2780 cells with cisplatin and VPA resulted in a significantly greater inhibition of cell viability compared to the treatment with either agent alone. Conclusion: Overall, it can be argued that VPA does not only cause inhibition of proliferation and induction of apoptosis in ovarian cancer cells but also helps to enhance the antiproliferative effects of cisplatin and results in the increased susceptibility to cisplatin in resistant cells. VPA may therefore be used to treat cancer in the future.

Phase I trial of belinostat with cisplatin and etoposide in advanced solid tumors, with a focus on neuroendocrine and small cell cancers of the lung

The standard-of-care for advanced small cell lung cancer (SCLC) is chemotherapy with cisplatin+etoposide (C+E). Most patients have chemosensitive disease at the outset, but disease frequently relapses and limits survival. Efforts to improve therapeutic outcomes in SCLC and other neuroendocrine cancers have focused on epigenetic agents, including the histone deacetylase inhibitor belinostat. The primary objective was to determine the maximum tolerated dose of the combination of belinostat (B) with C+E. Belinostat was administered as a 48-h continuous intravenous infusion on days 1-2; cisplatin was administered as a 1-h intravenous infusion on day 2; and etoposide was administered as a 1-h intravenous infusion on days 2, 3, and 4. Twenty-eight patients were recruited in this single-center study. The maximum tolerated dose was belinostat 500 mg/m/24 h, cisplatin 60 mg/m, and etoposide 80 mg/m. The combination was safe, although some patients were more susceptible to adverse events. Hematologic toxicities were most commonly observed. Objective responses were observed in 11 (39%) of 28 patients and seven (47%) of 15 patients with neuroendocrine tumors (including SCLC). Patients carrying more than three copies of variant UGT1A1 (*28 and *60) had higher serum levels of belinostat because of slower clearance. DNA damage peaked at 36 h after the initiation of belinostat, as did global lysine acetylation, but returned to baseline 12 h after the end of infusion. The combination of B+C+E is safe and active in SCLC and other neuroendocrine cancers. Future phase II studies should consider genotyping patients for UGT1A1*28 and UGT1A1*60 and to identify patients at an increased risk of adverse events.

Analysis of the Differentially Expressed Genes Induced by Cisplatin Resistance in Oral Squamous Cell Carcinomas and Their Interaction

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a solid tumor, which originates from squamous epithelium, with about 400,000 new-cases/year worldwidely. Presently, chemoradiotherapy is the most important adjuvant treatment for OSCC, mostly in advanced tumors. However, clinical resistance to chemotherapy still leads to poor prognosis of OSCC patients. Via high-throughput analysis of gene expression database of OSCC, we investigated the molecular mechanisms underlying cisplatin resistance in OSCC, analyzing the differentially expressed genes (DEGs) and their regulatory relationship, to clarify the molecular basis of OSCC chemotherapy resistance and provide a theoretical foundation for the treatment of patients with OSCC and individualized therapeutic targets accurately.

METHODS

Datasets related to "OSCC" and "cisplatin resistance" (GSE111585 and GSE115119) were downloaded from the GEO database and analyzed by GEO2R. Venn diagram was used to obtain drug-resistance-related DEGs. Functional enrichment analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis were performed on DEGs using The Database for Annotation, Visualization and Integrated Discovery (DAVID) software. Protein-protein interaction (PPI) network was constructed by STRING (search tool for recurring instances of neighbouring genes) database. Potential target genes of miRNA were predicted via miRDB, and cBioportal was used to analyze the function and survival of the potential functional genes.

RESULTS

Forty-eight upregulated DEGs and 49 downregulated DEGs were obtained from the datasets, with cutoff as p < 0.01 and |log FC| > 1. The DEGs in OSCC mainly enriched in cell proliferation regulation, and chemokine activity. In PPI network with hub score > 300, the hub genes were identified as NOTCH1, JUN, CTNNB1, CEBPA, and ETS1. Among miRNA-mRNA targeting regulatory network, hsa-mir-200c-3p, hsa-mir-200b-3p, hsa-mir-429, and hsa-mir-139-5p were found to simultaneously regulate multiple hub genes. Survival analysis showed that patients with high CTNNB1 or low CEBPA expression had poor outcome.

CONCLUSIONS

In the OSCC cisplatin-resistant cell lines, NOTCH1, JUN, CTNNB1, CEBPA, and ETS1 were found as the hub genes involved in regulating the cisplatin resistance of OSCC. Members of the miR-200 family may reverse drug resistance of OSCC cells by regulating the hub genes, which can act as potential targets for the treatment of OSCC patients with cisplatin resistance.

The FACT inhibitor CBL0137 Synergizes with Cisplatin in Small-Cell Lung Cancer by Increasing NOTCH1 Expression and Targeting Tumor-Initiating Cells

Traditional treatments of small-cell lung cancer (SCLC) with cisplatin, a standard-of-care therapy, spare the tumor-initiating cells (TIC) that mediate drug resistance. Here we report a novel therapeutic strategy that preferentially targets TICs in SCLC, in which cisplatin is combined with CBL0137, an inhibitor of the histone chaperone facilitates chromatin transcription (FACT), which is highly expressed in TICs. Combination of cisplatin and CBL0137 killed patient-derived and murine SCLC cell lines synergistically. In response to CBL0137 alone, TICs were more sensitive than non-TICs, in part, because CBL0137 increased expression of the tumor suppressor NOTCH1 by abrogating the binding of negative regulator SP3 to the NOTCH1 promoter, and in part because treatment decreased the high expression of stem cell transcription factors. The combination of cisplatin and CBL0137 greatly reduced the growth of a patient-derived xenograft in mice and also the growth of a syngeneic mouse SCLC tumor. Thus, CBL0137 can be a highly effective drug against SCLC, especially in combination with cisplatin.Significance: These findings reveal a novel therapeutic regimen for SCLC, combining cisplatin with an inhibitor that preferentially targets tumor-initiating cells. Cancer Res; 78(9); 2396-406. ©2018 AACR.

Targeted therapy of gastroenteropancreatic neuroendocrine tumours: preclinical strategies and future targets

Molecular targeted therapy of advanced neuroendocrine tumours (NETs) of the gastroenteropancreatic (GEP) system currently encompasses approved therapy with the mammalian target of rapamycin (mTOR) inhibitor everolimus and the multi-tyrosinkinase inhibitor sunitinib. However, clinical efficacy of these treatment strategies is limited by low objective response rates and limited progression-free survival due to tumour resistance. Further novel strategies for molecular targeted therapy of NETs of the GEP system are needed. This paper reviews preclinical research models and signalling pathways in NETs of the GEP system. Preclinical and early clinical data on putative novel targets for molecular targeted therapy of NETs of the GEP system are discussed, including PI3K, Akt, mTORC1/mTORC2, GSK3, c-Met, Ras-Raf-MEK-ERK, embryogenic pathways (Hedgehog, Notch, Wnt/beta-catenin, TGF-beta signalling and SMAD proteins), tumour suppressors and cell cycle regulators (p53, cyclin-dependent kinases (CDKs) CDK4/6, CDK inhibitor p27, retinoblastoma protein (Rb)), heat shock protein HSP90, Aurora kinase, Src kinase family, focal adhesion kinase and epigenetic modulation by histone deacetylase inhibitors.

Correlation between histone acetylation and expression of Notch1 in human lung carcinoma and its possible role in combined small-cell lung carcinoma

Combined small-cell lung carcinoma (cSCLC) is composed of small-cell lung carcinoma (SCLC) admixed with non-small-cell lung carcinoma (NSCLC). Evaluating the molecular differences between SCLC and NSCLC could lead to a better understanding of the pathogenesis of such neoplasms. Therefore, in this study, we investigated the correlation between histone acetylation and Notch1 expression in lung carcinoma. Using chromatin immunoprecipitation (ChIP) assay, we measured the level of acetylated histone H3 around the promoter region of Notch1 in SCLC and NSCLC cells. We then treated SCLC cells with trichostatin A (TSA) and characterized the level of histone H3 acetylation at Notch1. In addition, TSA-treated cells were injected into immune-compromised mice, for analysis of the ex vivo tumor xenograft phenotype. The level of acetylated histone H3 surrounding the Notch1 promoter was lower in lung cancer cells not expressing Notch1. Tumors originated from TSA-treated SCLC cells occasionally formed an epithelial-like glandular arrangement of cells; with Notch1 expression and decreased expression of neuroendocrine (NE) markers. Histone deacetylation around the promoter region of Notch1 inhibits Notch1 protein expression in SCLC and the restoration of Notch1 expression in SCLC leads to the concurrent appearance of epithelial-like areas within the SCLC, which could provide a possible mechanism for histogenesis of cSCLC.

Suberoyl bis-hydroxamic acid activates Notch1 signaling and induces apoptosis in anaplastic thyroid carcinoma through p53

Anaplastic thyroid cancer (ATC), usually derived from well-differentiated thyroid cancers is one of the most lethal human endocrine malignancies. In the present study, we report that in human ATC tumor tissue samples exist undetectable Notch1 and the active Notch1 intracellular domain could not be detected in ATC-CAL-62 cells. Interesting, suberoyl bis-hydroxamic acid (SBHA) administration could induce Notch1 intracellular domain levels in a dose-dependent manner, coupled with the increase of p53 and p21. Furthermore, ectopic expression of Notch1 or deletion of p53 with small-interfering RNA was able to abolish the effects of SBHA to elevation of Notch1 and p53 in ATC cells. As a result, SBHA treatment efficiently induced ATC cell apoptosis. These results indicate that SBHA may play antitumor functions via regulating Notch1/p53 signals, and highlight that SBHA could have clinical potential to benefit the therapy of ATC patients.

Evaluation of role of Notch3 signaling pathway in human lung cancer cells

There is still a debate on the extent to which Notch3 signaling is involved in lung carcinogenesis and whether such function is dependent on cancer type or not.

PURPOSE

To evaluate Notch3 expression in different types of human lung cancer cells.

METHODS

Notch3 was detected in human lung cancer cell lines and in tissues. Then, small interfering RNA (siRNA) was used to down-regulate the expression of Notch3 in H69AR small cell lung carcinoma (SCLC) cells; two non-small cell lung carcinoma (NSCLC) cells; A549 adenocarcinoma (ADC); and H2170 squamous cell carcinoma (SCC). In addition, Notch3 intracellular domain (N3ICD) plasmid was transfected into H1688 human SCLC cells. We observed the effect of deregulating Notch3 signaling on the following cell properties: Notch-related proteins, cell morphology, adhesion, epithelial-mesenchymal transition (EMT), motility, proliferation and neuroendocrine (NE) features of SCLC.

RESULTS

Notch3 is mainly expressed in NSCLC, and the expression of Notch1, Hes1 and Jagged1 is affected by Notch3. Notch3 has opposite functions in SCLC and NSCLC, being a tumor suppressor in the former and tumor promoting in the latter, in the context of cell adhesion, EMT and motility. Regarding cell proliferation, we found that inhibiting Notch3 in NSCLC decreases cell proliferation and induces apoptosis in NSCLC. Notch3 has no effect on cell proliferation or NE features of SCLC.

CONCLUSION

Notch3 signaling in lung carcinoma is dependent on cell type. In SCLC, Notch3 behaves as a tumor suppressor pathway, while in NSCLC it acts as a tumor-promoting pathway.

The Histone Deacetylase Inhibitor Vaproic Acid Induces Cell Growth Arrest in Hepatocellular Carcinoma Cells via Suppressing Notch Signaling

Hepatocellular carcinoma (HCC) is a type of malignant cancer. Notch signaling is aberrantly expressed in HCC tissues with more evidence showing that this signaling plays a critical role in HCCs. In the present study, we investigate the effects of the anti-convulsant drug valproic acid (VPA) in HCC cells and its involvement in modulating Notch signaling. We found that VPA, acting as a histone deacetylase (HDAC) inhibitor, induced a decrease in HDAC4 and an increase in acetylated histone 4 (AcH4) and suppressed HCC cell growth. VPA also induced down-regulation of Notch signaling via suppressing the expression of Notch1 and its target gene HES1, with an increase of tumor suppressor p21 and p63. Furthermore, Notch1 activation via overexpressing Notch1 active form ICN1 induced HCC cell proliferation and anti-apoptosis, indicating Notch signaling played an oncogenic role in HCC cells. Meanwhile, VPA could reverse Notch1-induced increase of cell proliferation. Interestingly, VPA was also observed to stimulate the expression of G protein-coupled somatostatin receptor type 2 (SSTR2) that has been used in receptor-targeting therapies. This discovery supports a combination therapy of VPA with the SSTR2-targeting agents. Our in vitro assay did show that the combination of VPA and the peptide-drug conjugate camptothecin-somatostatin (CPT-SST) displayed more potent anti-proliferative effects on HCC cells than did each alone. VPA may be a potential drug candidate in the development of anti-HCC drugs via targeting Notch signaling, especially in combination with receptor-targeting cytotoxic agents.

Effects of sodium valproate on the growth of human ovarian cancer cell line HO8910

To explore a possible new treatment for human ovarian cancer, we studied the effects of sodium valproate on the growth of the HO8910 human cell line. HO8910 cells were cultured in vitro and treated with different concentrations of sodium valproate. Cell proliferation, cell cycling, and apoptosis were measured by flow cytometry, cell morphology under a microscope, and expression levels of WWOX and P27 by Western blotting and RT-PCR. Tumor xenografts were established to determine in vivo effects of sodium valproate. Our results showed that cell proliferation was decreased with increasing concentration of sodium valproate, with features of cytoplasmic retraction and floating cells. Moreover, cell cycle analysis revealed a higher apoptosis rate and G0/ G1 phase in the sodium valproate experimental group than in the control group. In addition, protein expression levels of WWOX and P27 were elevated. Importantly, sodium valproate decreased in vivo xenograft tumor burden and up-regulated WWOX and P27 expression in nude mice. In conclusion, sodium valproate might play a role in inhibition and control of ovarian cancer cell line HO8910 by inhibiting cell proliferation, interfering with the cell cycle and promoting apoptosis, so that it may be effective in the clinical treatment of ovarian cancer.

Notch1 signaling controls cell proliferation, apoptosis and differentiation in lung carcinoma

OBJECTIVES

The role of Notch signaling in human lung cancer still remains unclear, and there has been and stills a debate, on the extent to which Notch ligands and receptors are involved in lung cancer development. This study was carried out to investigate the role of Notch1 signaling in the proliferation and differentiation of human lung cancer cells.

METHODS

We used small interfering RNA (siRNA) technology to down-regulate the expression of Notch1 in small cell lung carcinoma (SCLC) cells; H69AR and SBC-3, as well as in non-small cell lung carcinoma (NSCLC) cells; A549 adenocarcinoma (ADC) and H2170 squamous cell carcinoma (SCC). Also, we transfected venus Notch1 intracellular domain (v.NICD) plasmid into the human SCLC line H69 and H1688. In addition, H1688 cells with activated Notch1 were injected into immune-compromised Rag2(-/-) Jak3(-/-) mice for analysis of ex vivo tumor growth and differentiation phenotype.

RESULTS

Notch1 controls cell proliferation and apoptosis in both SCLC and A549; but not in H2170 cell line. Overexpression of Notch1 in SCLC markedly decreased cell proliferation via apoptosis. The subcutaneous tumors arising from xenotransplaned SCLC cells transfected with Notch1 showed "epithelial-like glandular" arrangement, with positive Alcian blue staining and reduction in neuroendocrine markers.

CONCLUSION

Notch1 up regulation has an inhibitory effect on cell growth and NE differentiation in SCLC, with induction of an epithelial-like morphology of cells in tissue samples. In NSCLC, Notch1 expression has a tumor inhibitory effect on ADC cells, but not SCC cells.

Long-term use of valproic acid in US veterans is associated with a reduced risk of smoking-related cases of head and neck cancer

BACKGROUND

Epigenetic events play a major role in the carcinogenesis of tobacco-related cancers. The authors conducted a retrospective cohort study to evaluate the effects of exposure to the anticonvulsant agent valproic acid (VPA), a histone deacetylase inhibitor, on the risk of developing cancers of the lung, head and neck, prostate, bladder, and colon.

METHODS

The study was based on the 2002 through 2008 National Veterans Affairs (VA) medical SAS data set linked to the VA Central Cancer Registry. The cohort was defined as subjects aged>40 years who were followed in the VA system for at least 1 year for 1 of 4 diagnoses for which a VPA indication exists (bipolar disorder, posttraumatic stress disorder, migraines, and seizures). Multivariable Cox proportional hazards models were used to estimate hazards ratios (HR) and 95% confidence intervals (95% CI) reflecting the association between use of VPA and cancer incidence.

RESULTS

VPA use was associated with a significant reduction in the risk of cancers of the head and neck (HR, 0.66; 95% CI, 0.48-0.92). Additional associations were noted with the duration of treatment and median VPA drug levels. No significant differences in cancer incidence were observed for cancers of the lung (HR, 1.00; 95% CI, 0.84-1.19), bladder (HR, 0.86; 95% CI, 0.64-1.15), colon (HR, 0.95; 95% CI, 0.74-1.22), and prostate (HR, 0.96; 95% CI, 0.88-1.12).

CONCLUSIONS

Use of VPA is associated with a lower risk of developing head and neck cancers.

Targeting the epigenome in lung cancer: expanding approaches to epigenetic therapy

Epigenetic aberrations offer dynamic and reversible targets for cancer therapy; increasingly, alteration via overexpression, mutation, or rearrangement is found in genes that control the epigenome. Such alterations suggest a fundamental role in carcinogenesis. Here, we consider three epigenetic mechanisms: DNA methylation, histone tail modification and non-coding, microRNA regulation. Evidence for each of these in lung cancer origin or progression has been gathered, along with evidence that epigenetic alterations might be useful in early detection. DNA hypermethylation of tumor suppressor promoters has been observed, along with global hypomethylation and hypoacetylation, suggesting an important role for tumor suppressor gene silencing. These features have been linked as prognostic markers with poor outcome in lung cancer. Several lines of evidence have also suggested a role for miRNA in carcinogenesis and in outcome. Cigarette smoke downregulates miR-487b, which targets both RAS and MYC; RAS is also a target of miR-let-7, again downregulated in lung cancer. Together the evidence implicates epigenetic aberration in lung cancer and suggests that targeting these aberrations should be carefully explored. To date, DNA methyltransferase and histone deacetylase inhibitors have had minimal clinical activity. Explanations include the possibility that the agents are not sufficiently potent to invoke epigenetic reversion to a more normal state; that insufficient time elapses in most clinical trials to observe true epigenetic reversion; and that doses often used may provoke off-target effects such as DNA damage that prevent epigenetic reversion. Combinations of epigenetic therapies may address those problems. When epigenetic agents are used in combination with chemotherapy or targeted therapy it is hoped that downstream biological effects will provoke synergistic cytotoxicity. This review evaluates the challenges of exploiting the epigenome in the treatment of lung cancer.

Valproic acid suppresses cervical cancer tumor progression possibly via activating Notch1 signaling and enhances receptor-targeted cancer chemotherapeutic via activating somatostatin receptor type II

PURPOSE

We investigated the effects of the anti-epilepsy drug valproic acid (VPA) alone and in combination in treating cervical cancer.

METHODS

VPA was investigated for its effects on cervical cancer Hela cell proliferation and tumor growth via in vitro and in vivo assays.

RESULTS

VPA induce cell growth suppression and cell cycle arrest, with an increase of Notch1 that acts as a tumor suppressor and the change of other tumor-associated genes such as p21, p63 and PCNA. VPA was also found to induce cell morphological change, with an increase of certain cell transformation markers such as snail1, snail2 and N-cadherin. Moreover, VPA could significantly up-regulate somatostatin receptor type II (SSTR2). Our in vivo study further demonstrated that VPA via inducing SSTR2 up-regulation extremely enhanced the anti-tumor ability of the SSTR2-preferential cytotoxic COL-SST conjugate in xenografts.

CONCLUSIONS

VPA could not only suppress tumor progression but also provide a novel promising therapeutic choice in combination with a receptor-targeted cytotoxic conjugate via activating the specific receptor.

Potential Therapeutic Role of Z-Isochaihulactone in Lung Cancer through Induction of Apoptosis via Notch Signaling

Lung cancer is one of the leading causes of cancer death in worldwide and required for novel therapeutic strategy. Our previous research demonstrated that the crude acetone extract of Bupleurum scorzonerifolium (BS-AE) and its component isochaihulactone induce antiproliferative and apoptotic effects on the lung adenocarcinoma cell line. Structural analysis has identified isochaihulactone as a lignan, with a chiral center and two racemic forms (Z-isochaihulactone and E-isochaihulactone). In this study, Z-isochaihulactone displayed significantly higher tumor cytotoxicity than E-isochaihulactone in A549 cells. The notch signaling pathway plays a pivotal role in determination of cell fate during development, while in lung cancer, it might have oncogenic or tumor-suppressive controversial functions. We showed that Z-isochaihulactone induced morphological changes in the A549 cells, inhibited cell growth, and arrested the cell cycle at the G2/M phase. It also induced upregulation of the active form of Notch1 (notch intracellular domain, NICD), which further induced p21 and c-Myc expression in time- and dose-dependent manners. Administrations of Z-isochaihulactone in nude mice can significantly inhibit tumor growth due to enhancement of NICD expression confirmed by immunohistochemical analysis. Taken together, our results supported that Z-isochaihulactone can efficiently inhibit tumorigenicity and be a potential compound for therapy.

Notch1 signaling is irresponsible to the anti-leukemic effect of HDACis in B-ALL Nalm-6 cells

B cell acute lymphoblastic leukemia (B-ALL) is an aggressive hematologic malignancy with limited treatment strategies. Histone deacetylases inhibitors (HDACis) are promising novel tools for cancer therapy, whose anti-tumor effects and the underlying mechanisms on B-ALL remain to be elucidated. Recently, Notch1 signaling activation has been reported to be involved in the anti-tumor effects of HDACis. This study was conducted to determine: the influence of two HDACis, valproic acid (VPA) and suberic bishydroxamic acid (SBHA), on Notch1 signaling as well as the role of Notch1 signaling in the anti-tumor effects of HDACis in B-ALL cells. To address this issue, we treated Nalm-6 B-ALL cell line with VPA and SBHA (HDACis), then, cell proliferation, cell cycle, apoptosis, and expression of Notch1 related genes were analyzed. We found that VPA and SBHA dramatically inhibited cell growth, induced a G1/S cell cycle block in accompany with an elevated level of P21(WAF1) protein in Nalm-6 cells. The levels of cleaved caspase-9, caspase-3, and PARP were elevated, indicating the activation of apoptosis. However, no change in the expression of Notch1 and its downstream genes were found by quantitative real-time PCR and Western blot. Our result suggested that Notch1 signaling is irresponsible for the anti-leukemic effect of HDACis in B-ALL cells. New hypotheses and future studies are needed to explore the underlying mechanisms of the anti-cancer effect in B-ALL.

Sodium valproate inhibits MDA-MB-231 breast cancer cell migration by upregulating NM23H1 expression

Breast cancer is a common cancer in women, with a highly variable course, from inoffensive to lethal. To find a more effective strategy for its treatment, sodium valproate has been tested as an anti-cancer drug; it is the only clinically available histone deacetylase inhibitor. However, data about the effects of sodium valproate on breast cancer are insufficient in both animals and humans; studies have yielded conflicting conclusions. In particular, little is known about the association between expression of the metastasis suppressor Nm23H1 gene and breast cancer. We hypothesized that sodium valproate regulates NM23H1 expression, and affects migration and/or invasion. We found that sodium valproate at concentrations of 0.8-3.2 mM inhibits migration and modulates Nm23H1 gene expression in a concentration-dependent manner. Confluent MDA-MB-231 cells were scratched by a micropipette tip after VPA treatment for 24 h; 24 h later, the scratch was almostly closed in the 0 mM VPA-treated cells, while the 3.2 mM VPA-treated cells migrated the slowest. The cell migration ratio exposed to 0.8, 1.6 and 3.2 mM VPA was about 66.67, 30.67 and 26.67% (P < 0.05). We also found evidence that sodium valproate upregulates NM23H1 expression, which is a clue to its anti-cancer mode of action. The NM23H1 gene expression was relative fold increased determined by Western blotting at 3.2 mM VPA. Collectively, these observations indicate that sodium valproate has potential for use in breast cancer treatment.

Hesperetin, a potential therapy for carcinoid cancer

BACKGROUND

The investigators' laboratory has demonstrated that the Notch1 signaling pathway acts as a tumor suppressor in carcinoid tumors. The aim of this study was to examine hesperetin, a flavonoid, as a potential Notch1 activator and carcinoid tumor suppressor.

METHODS

A high-throughput drug screen revealed hesperetin as a Notch1 activator. Human gastrointestinal carcinoid (BON) cell growth after hesperetin treatment was assessed with a 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide assay. Western blots were used to measure neuroendocrine tumor markers, human achaete-scute complex-like 1, and chromogranin A. Notch1 expression was measured using western blot analysis and real-time polymerase chain reaction.

RESULTS

Hesperetin induced cell death in a dose-dependent manner and reduced achaete-scute complex-like 1 and chromogranin A expression, with a concomitant rise in Notch1 levels. It also induced Notch1 messenger ribonucleic acid, indicating regulation at the transcriptional level.

CONCLUSION

Hesperetin induces Notch1 expression in carcinoid cells, subsequently suppressing tumor cell proliferation and bioactive hormone production. This provides evidence for further study into hesperetin as a potential treatment for carcinoid cancer.

The biology of HDAC in cancer: the nuclear and epigenetic components

Traditionally, cancer has been regarded to originate from genetic alterations such as mutations, deletions, rearrangements as well as gene amplifications, leading to abnormal expression of tumor suppressor genes and oncogenes. An increasing body of evidence indicates that in addition to changes in DNA sequence, epigenetic alterations contribute to cancer initiation and progression. In contrast to genetic mutations, epigenetic changes are reversible and therefore an attractive target for cancer therapy. Many epi-drugs such as histone deacetylase (HDAC) inhibitors showed anticancer activity in cell culture and animal models of carcinogenesis. Recently, the two HDAC inhibitors suberoylanilide hydroxamic acid (SAHA, Vorinostat) and Romidepsin (Depsipeptide, FK228) were FDA approved for the treatment of cutaneous T-cell lymphoma (CTCL). Although HDAC inhibitors are potent anticancer agents, these compounds act against several HDAC family members potentially resulting in numerous side effects. This stems from the fact that HDACs play crucial roles in a variety of biological processes including cell cycle progression, proliferation, differentiation, and development. Consistently, mice deficient in single HDACs mostly exhibit severe phenotypes. Therefore, it is necessary to specify the cancer-relevant HDACs in a given tumor type in order to design selective inhibitors that target only cancer cells without affecting normal cells. In this chapter, we summarize the current state of knowledge of individual nuclear HDAC family members in development and tumorigenesis, their contribution to the hallmarks of cancer, and the involvement of HDAC family members in different types of human malignancies.

Does valproic acid induce neuroendocrine differentiation in prostate cancer?

Valproic Acid (VPA) is a histone deacetylase inhibitor that holds promise for cancer therapy. Here, we investigate whether VPA treatment induces neuroendocrine differentiation of Prostate Cancer (PCa). A tissue microarray of VPA-treated and untreated tumor xenografts and cell lines of human PCa (LNCaP, C4-2, DU145, and PC-3) were generated and were analyzed by immunohistochemical analysis (IHC) for NE markers chromogranin A (CgA), synaptophysin, and NCAM (neural cell adhesion molecule). Western blot analysis for CgA was performed to confirm the results of the TMA. IHC analysis did not reveal any induction of CgA, synaptophysin, or NCAM in any xenograft after VPA treatment in vivo. In vitro, VPA treatment induced little synaptophysin expression in C4-2 and PC-3 cells and NCAM expression in LNCaP and PC-3 cells. In the case of CgA, VPA treatment decreased its expression in vitro in a dose-dependent manner, as determined by western blot analysis. Thus our data demonstrates that VPA does not induce NE differentiation of PCa cells in the physiologically relevant in vivo setting.

The effect of a PP2A inhibitor on the nuclear receptor corepressor pathway in glioma

OBJECT

Nuclear receptor corepressor (N-CoR) forms a complex that maintains neural stem cells in an undifferentiated state through transcriptional repression. Recently, it has been shown that N-CoR is overexpressed in glioblastoma multiforme (GBM) tumor stem cells and has a putative role in maintaining these cells in an undifferentiated immortal state. To determine the effects of disruption of N-CoR complex function by serine/threonine protein phosphatase 2A (PP2A) inhibition on GBM tumor cell differentiation and proliferation, the authors developed and investigated a competitive small molecule inhibitor (LB1) of PP2A in GBM.

METHODS

The authors investigated the effects of LB1 on GBM proliferation and molecular differentiation pathways using in vitro and in vivo studies.

RESULTS

The LB1 inhibited PP2A, leading to increased levels of phosphorylated Akt kinase and decreased NCoR expression, as well as dose-dependent antiproliferative activity in cultured U87 and U251 malignant glioma cells (dose range 1-10 microM). Systemic LB1 treatment (1.5 mg/kg/day for 21 days) had significant tumor antiproliferative effects in mice harboring U87 glioma xenografts (73% mean reduction in tumor volume compared with controls; p < 0.001). Moreover, a reduction in PP2A expression and activity after LB1 treatment in vivo correlated with increased Akt phosphorylation, reduced nuclear N-CoR expression and N-CoR cytoplasmic translocation, and increased accumulation of acetylated core histones, which coincided with the appearance of glial fibrillary acidic protein-expressing tumor cells.

CONCLUSIONS

These findings indicate that PP2A inhibition effectively disrupts N-CoR complex function/expression and leads to cytoplasmic translocation of N-CoR with subsequent tumor cell differentiation and/or death. Therapeutic paradigms that target N-CoR function in the cancer stem cell component of malignant gliomas may have treatment utility.

Preclinical evidence for a beneficial impact of valproate on the response of small cell lung cancer to first-line chemotherapy

Prognosis of small cell lung carcinoma (SCLC) is particularly poor, less than 5% of patients with extensive stage being alive after two years. We hypothesized that SCLC chemotherapy could be improved by using histone deacetylase (HDAC) inhibitors based on their ability to interfere with lysine acetylation and to alter gene expression. The goal of this study was to evaluate the anticancer efficacy of a HDAC inhibitor (valproate: VPA) on SCLC cells in combination with the standard chemotherapeutic first-line regimen (cisplatin+etoposide). We show that VPA induces apoptosis of small cell lung cancer cell lines and improves efficacy of cisplatin combined with etoposide. Both mitochondrial and death receptor pathways are involved in VPA-induced apoptosis. As expected for an HDAC inhibitor, VPA hyperacetylates histone H3. The mechanism of VPA pro-apoptotic activity involves induction of p21, inhibition of Bcl-xL, cleavage of Bid and phosphorylation of Erk and H2AX. In the presence of VPA, Bax is translocated from the cytoplasm to the mitochondria and cleaved in an 18kDa isoform. Cytochrome c is released from the mitochondria into the cytosol. Transcriptomic analyses by microarray show that VPA modulates transcription of genes (Na(+)/K(+) ATPase, Bcl-xL) involved in chemoresistance to cisplatin and etoposide. Finally, the efficacy of VPA combined with cisplatin and etoposide is supported by preclinical models of SCLC cells engrafted into SCID mice. Together, these data demonstrate that VPA augments anticancer activity of cisplatin and etoposide, two components of the standard first-line chemotherapy of small cell lung cancer.

Large-cell neuroendocrine carcinoma of the ampulla of Vater

Large-cell neuroendocrine carcinoma is a high-grade neuroendocrine carcinoma, originally described in the lung. The tumor rarely occurs in extrapulmonary sites like the gastrointestinal tract, and only few examples have been described in the ampulla of Vater. A new case of large-cell neuroendocrine carcinoma of the ampulla of Vater in a 60-year-old man is reported. After pancreatoduodenectomy, macroscopic examination revealed ulcerated tumor in the region of the ampulla of Vater. Microscopically, the tumor exhibited organoid, predominantly nested growth pattern, consisting of large, polygonal cells with pleomorphic nuclei. Average number of mitoses was 36 per 10 high-power fields. Small and large areas of necrosis were identified. Immunohistochemically, the tumor cells were positive for synaptophysin, chromogranin A, PGP 9.5, neuron-specific enolase, pancytokeratin, CK8 and somatostatin and negative for CK7, CK20, S-100, TTF-1, HMB-45, CD117, E-cadherin and regulatory peptides. Ki-67 proliferative index was 41%. Histone deacetylase (HDAC) analysis showed almost identical results for HDAC1, HDAC2 and HDAC3--60, 60.3 and 61%, respectively. Two months after surgery, liver metastases occurred, confirming highly aggressive behavior of large-cell neuroendocrine carcinoma.

The HDAC inhibitor panobinostat (LBH589) inhibits mesothelioma and lung cancer cells in vitro and in vivo with particular efficacy for small cell lung cancer

Lung cancer is the leading cause of cancer deaths in the United States. Current therapies are inadequate. Histone deacetylase inhibitors (HDACi) are a recently developed class of anticancer agents that cause increased acetylation of core histones and nonhistone proteins leading to modulation of gene expression and protein activity involved in cancer cell growth and survival pathways. We examined the efficacy of the HDACi panobinostat (LBH589) in a wide range of lung cancers and mesotheliomas. Panobinostat was cytotoxic in almost all 37 cancer cell lines tested. IC(50) and LD(50) values were in the low nmol/L range (4-470 nmol/L; median, 20 nmol/L). Small cell lung cancer (SCLC) cell lines were among the most sensitive lines, with LD(50) values consistently <25 nmol/L. In lung cancer and mesothelioma animal models, panobinostat significantly decreased tumor growth by an average of 62% when compared with vehicle control. Panobinostat was equally effective in immunocompetent and severe combined immunodeficiency mice, indicating that the inhibition of tumor growth by panobinostat was not due to direct immunologic effects. Panobinostat was, however, particularly effective in SCLC xenografts, and the addition of the chemotherapy agent etoposide augmented antitumor effects. Protein analysis of treated tumor biopsies revealed elevated amounts of cell cycle regulators such as p21 and proapoptosis factors, such as caspase 3 and 7 and cleaved poly[ADP-ribose] polymerase, coupled with decreased levels of antiapoptotic factors such as Bcl-2 and Bcl-X(L). These studies together suggest that panobinostat may be a useful adjunct in the treatment of thoracic malignancies, especially SCLC.

Histone deacetylase inhibitors upregulate Notch-1 and inhibit growth in pheochromocytoma cells

BACKGROUND

The histone deacetylase (HDAC) inhibitors valproic acid (VPA) and suberoyl bis-hydroxamic acid (SBHA) have been demonstrated recently to be strong Notch-1 activators. Upregulation of the Notch-1 pathway has been shown to limit growth and suppress hormonal secretion in neuroendocrine (NE) neoplasms. We hypothesized that HDAC inhibition would be an effective strategy to activate the Notch-1 pathway and inhibit growth and hormonal secretion in pheochromocytoma cells.

METHODS

Pheochromocytoma PC-12 cells were treated with up to 8 mmol/L VPA or 40 micromol/L SBHA for 2 days. NE tumor markers achaete-scute complex-like 1 (ASCL1) and chromogranin A (CgA) were measured by Western analysis after treatment. Growth was assessed by a cellular proliferation assay; Western analysis was used to determine the mechanism of growth regulation.

RESULTS

HDAC inhibitor treatment caused a dose-dependent decrease in ASCL1 and CgA while increasing the amount of active Notch-1 protein; with a 6-day treatment, dose-dependent growth inhibition and cleavage of the apoptotic markers caspase-3 and poly-ADP ribose phosphate was observed.

CONCLUSION

VPA and SBHA upregulate Notch-1 effectively, suppress NE tumor markers, and decrease growth via apoptosis of pheochromocytoma cells in vitro. Activation of the Notch-1 signaling pathway with HDAC inhibitors may represent a new strategy for treating pheochromocytomas.

Combination therapy with histone deacetylase inhibitors and lithium chloride: a novel treatment for carcinoid tumors

In carcinoid cell lines, the histone deacetylase (HDAC) inhibitors valproic acid (VPA) and suberoyl bis-hydroxamic acid (SBHA) activate the Notch1 pathway, whereas lithium inhibits glycogen synthase kinase-3beta (GSK-3beta). These compounds limit growth and decrease hormonal secretion in vitro. We hypothesized that lower-dose combination therapy of HDAC inhibitors and lithium chloride could achieve similar growth inhibition to that of the drugs alone. Gastrointestinal and pulmonary carcinoid cells were treated with either VPA or SBHA and lithium chloride for up to 48 hours. Western blot analysis was used to measure the effects on the Notch1 and GSK-3beta pathways and the neuroendocrine tumor marker chromogranin A (CgA). Growth was measured by a cellular proliferation assay. With lower-dose combination therapy, a decrease in CgA was observed. The HDAC inhibitors increased the amount of active Notch1 protein, whereas treatment with lithium was associated with inhibition of GSK-3beta. Moreover, growth was inhibited with lower-dose combination therapy. Treatment of carcinoid cells with either VPA or SBHA and lithium chloride suppresses the neuroendocrine marker CgA while upregulating Notch1 and inhibiting GSK-3beta. This combination effectively reduces growth. Thus, lower-dose combination therapy may be a viable therapeutic approach for carcinoid tumors.

Inhibition of growth in medullary thyroid cancer cells with histone deacetylase inhibitors and lithium chloride

BACKGROUND

While representing only 3% of thyroid malignancies, medullary thyroid cancer (MTC) accounts for 14% of thyroid cancer deaths. MTC has a high rate of recurrence and lacks effective treatments. The histone deacetylase (HDAC) inhibitors valproic acid (VPA) and suberoyl bis-hydroxamic acid (SBHA) activate the Notch1 signaling pathway, while lithium chloride inhibits the glycogen synthase kinase-3ss (GSK-3ss) pathway. These compounds have been shown to limit growth and suppress hormonal secretion; thus, targeting different signaling pathways may be an effective treatment.

METHODS

MTC cells were treated with varying combinations of up to 20 mM lithium chloride with either 3 mM VPA or 20 muM SBHA for 48 h. Western analysis was used to measure the effects on Notch1, GSK-3ss, and neuroendocrine (NE) markers. Growth was assessed by a methylthiazolyldiphenyl-tetrazolium (MTT) bromide cellular proliferation assay. Western analysis was used to determine the mechanism of growth regulation.

RESULTS

Combination therapy increased active Notch1, inhibited the GSK-3ss pathway, and decreased NE markers. Additive inhibition of growth was observed with combination therapy. Lower-dose combination therapy achieved greater decreases on NE markers and growth than treatment with any of the drugs alone. Moreover, an increase in the cleavage of the apoptotic markers caspase-3 and PARP was observed.

CONCLUSIONS

Combination therapy with lithium chloride and HDAC inhibitors suppresses NE markers and decreases growth via apoptosis of MTC cells in vitro. With the possibility of increased efficacy and decreased toxicity, combination therapy may represent a new strategy to treat MTC.