Effect of histone deacetylase inhibitor in combination with 5-fluorouracil on pancreas cancer and cholangiocarcinoma cell lines

The bacterial metabolite, lithocholic acid, has antineoplastic effects in pancreatic adenocarcinoma

Lithocholic acid (LCA) is a secondary bile acid. LCA enters the circulation after bacterial synthesis in the gastrointestinal tract, reaches distantly located cancer cells, and influences their behavior. LCA was considered carcinogenic, but recent studies demonstrated that LCA has antitumor effects. We assessed the possible role of LCA in pancreatic adenocarcinoma. At the serum reference concentration, LCA induced a multi-pronged antineoplastic program in pancreatic adenocarcinoma cells. LCA inhibited cancer cell proliferation and induced mesenchymal-to-epithelial (MET) transition that reduced cell invasion capacity. LCA induced oxidative/nitrosative stress by decreasing the expression of nuclear factor, erythroid 2-like 2 (NRF2) and inducing inducible nitric oxide synthase (iNOS). The oxidative/nitrosative stress increased protein nitration and lipid peroxidation. Suppression of oxidative stress by glutathione (GSH) or pegylated catalase (pegCAT) blunted LCA-induced MET. Antioxidant genes were overexpressed in pancreatic adenocarcinoma and decreased antioxidant levels correlated with better survival of pancreatic adenocarcinoma patients. Furthermore, LCA treatment decreased the proportions of cancer stem cells. Finally, LCA induced total and ATP-linked mitochondrial oxidation and fatty acid oxidation. LCA exerted effects through the farnesoid X receptor (FXR), vitamin D receptor (VDR), and constitutive androstane receptor (CAR). LCA did not interfere with cytostatic agents used in the chemotherapy of pancreatic adenocarcinoma. Taken together, LCA is a non-toxic compound and has antineoplastic effects in pancreatic adenocarcinoma.

The roles of epigenetic regulation in cholangiocarcinogenesis

Cholangiocarcinoma (CCA), a heterogeneous malignancy of bile duct epithelial cells, is characterized by aggressiveness, difficult diagnosis, and poor prognosis due to limited understanding and lack of effective therapeutic strategies. Genetic and epigenetic alterations accumulated in CCA cells can cause the aberrant regulation of oncogenes and tumor suppressors. Epigenetic alterations with histone modification, DNA methylation, and noncoding RNA modulation are associated with the carcinogenesis of CCA. Mutation or silencing of genes by various mechanisms can be a frequent event during CCA development. Alterations in histone acetylation/deacetylation at the posttranslational level, DNA methylation at promoters, and noncoding RNA regulation contribute to the heterogeneity of CCA and drive tumor development. In this review article, we mainly focus on the roles of epigenetic regulation in cholangiocarcinogenesis. Alterations in epigenetic modification can be potential targets for the therapeutic management of CCA, and epigenetic targets may become diagnostic biomarkers of CCA.

Bile Acids and Microbiota Interplay in Pancreatic Cancer

Evidence suggests the involvement of the microbiota, including oral, intra-tumoral and gut, in pancreatic cancer progression and response to therapy. The gut microbiota modulates the bile acid pool and is associated with maintaining host physiology. Studies have shown that the bile acid/gut microbiota axis is dysregulated in pancreatic cancer. Bile acid receptor expression and bile acid levels are dysregulated in pancreatic cancer as well. Studies have also shown that bile acids can cause pancreatic cell injury and facilitate cancer cell proliferation. The microbiota and its metabolites, including bile acids, are also altered in other conditions considered risk factors for pancreatic cancer development and can alter responses to chemotherapeutic treatments, thus affecting patient outcomes. Altogether, these findings suggest that the gut microbial and/or bile acid profiles could also serve as biomarkers for pancreatic cancer detection. This review will discuss the current knowledge on the interaction between gut microbiota interaction and bile acid metabolism in pancreatic cancer.

Hesperidin delays cell cycle progression into the G0/G1 phase via suspension of MAPK signaling pathway in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) derived from epithelial cells of bile ducts is highly aggressive tumor. Hesperidin extracted from citrus fruits is a promising antitumor compound. The purpose of this study is to explore molecular mechanism by which hesperidin affects cholangiocarcinoma progression. Cellular functional experiments were performed and subcutaneous transplant xenograft model was established. Our findings indicated that hesperidin suppressed iCCA cell proliferation in time- and concentration-dependent manners. Hesperidin treatment induced cell cycle arrest at G0/G1 phase, whereas it has no effect on cell apoptosis. Further, data revealed that hesperidin attenuated MEK5 and ERK5 phosphorylation and inhibited ERK5 nuclear localization by reducing MEKK2 activity in MAPK signaling pathway. It could cause alterations in expression of the downstream genes, including CDK4, CDK6 (cell cycle protein kinases), Cyclin D1 (a G1/S checkpoint), P21, and P27 (two G1-checkpoint CDK inhibitors), thereby arresting cell cycle distribution of iCCA cells in the G0/G1 phase. BIX02189 treatment, a specific inhibitor of MEK5, in combination with hesperidin displayed synergistic inhibitory effects on cell cycle arrest and gene expressions. Furthermore, hesperidin administration alone or in combination with MEK5 inhibitor BIX02189 restrained iCCA tumor growth in vivo. Taken together, these results confirmed that hesperidin regulated the expression of cell cycle-related genes by inhibiting the activation of MEKK2/MEK5/ERK5 signaling pathway, inducing iCCA cell cycle arrest at the G0/G1 phase. Our study provides a theoretical foundation and experimental basis for further development of hesperidin as a therapeutic agent for iCCA treatment.

Histone deacetylases: A novel class of therapeutic targets for pancreatic cancer

Pancreatic cancer is the seventh leading cause of cancer death worldwide, with a low 5-year survival rate. Novel agents are urgently necessary to treat the main pathological type, known as pancreatic ductal carcinoma (PDAC). The dysregulation of histone deacetylases (HDACs) has been identified in association with PDAC, which can be more easily targeted by small molecular inhibitors than gene mutations and may represent a therapeutic breakthrough for PDAC. However, the contributions of HDACs to PDAC remain controversial, and pharmacokinetic challenges have limited the application of HDAC inhibitors (HDACis) in PDAC. This review summarizes the mechanisms associated with success and failure of HDACis in PDAC and discusses the recent progress made in HDACi development and application, such as combination therapies designed to enhance efficacy. More precise strategies involving HDACis might eventually improve the outcomes of PDAC treatment.

HDAC Screening Identifies the HDAC Class I Inhibitor Romidepsin as a Promising Epigenetic Drug for Biliary Tract Cancer

Simple Summary

Biliary tract cancer (BTC) is a rare disease with dismal outcomes. Therefore, the investigation of new therapeutic targets is urgently required. In this study, we demonstrate that histone deacetylases (HDACs) are expressed in BTC cell lines and that treatment of BTC cells with different HDAC class inhibitors reduces cell viability. Specifically, we found that BTC cells are vulnerable to the HDAC class I inhibitor romidepsin. Treatment with romidepsin resulted in apoptotic cell death of BTC cells and reduced HDAC activity. Furthermore, romidepsin augmented the cytotoxic effect of the standard chemotherapeutic cisplatin. HDAC class I proteins were also expressed in BTC patient samples. We detected that BTC patients with high HDAC-2-expressing tumors showed a significantly shorter survival. In summary, we were able to demonstrate that BTC cells are vulnerable to HDAC inhibition and that the HDAC class I inhibitor romidepsin might be a promising anti-BTC substance.

Abstract

Inhibition of histone deacetylases (HDACs) is a promising anti-cancer approach. For biliary tract cancer (BTC), only limited therapeutic options are currently available. Therefore, we performed a comprehensive investigation of HDAC expression and pharmacological HDAC inhibition into a panel of eight established BTC cell lines. The screening results indicate a heterogeneous expression of HDACs across the studied cell lines. We next tested the effect of six established HDAC inhibitors (HDACi) covering pan- and class-specific HDACis on cell viability of BTC cells and found that the effect (i) is dose- and cell-line-dependent, (ii) does not correlate with HDAC isoform expression, and (iii) is most pronounced for romidepsin (a class I HDACi), showing the highest reduction in cell viability with IC₅₀ values in the low-nM range. Further analyses demonstrated that romidepsin induces apoptosis in BTC cells, reduces HDAC activity, and increases acetylation of histone 3 lysine 9 (H3K9Ac). Similar to BTC cell lines, HDAC 1/2 proteins were heterogeneously expressed in a cohort of resected BTC specimens (n = 78), and their expression increased with tumor grading. The survival of BTC patients with high HDAC-2-expressing tumors was significantly shorter. In conclusion, HDAC class I inhibition in BTC cells by romidepsin is highly effective in vitro and encourages further in vivo evaluation in BTC. In situ assessment of HDAC 2 expression in BTC specimens indicates its importance for oncogenesis and/or progression of BTC as well as for the prognosis of BTC patients.

Role of microbiota-derived short-chain fatty acids in cancer development and prevention

Following cancer, cells in a particular tissue can no longer respond to the factors involved in controlling cell survival, differentiation, proliferation, and death. In recent years, it has been indicated that alterations in the gut microbiota components, intestinal epithelium, and host immune system are associated with cancer incidence. Also, it has been demonstrated that the short-chain fatty acids (SCFAs) generated by gut microbiota are vitally crucial in cell homeostasis as they contribute to the modulation of histone deacetylases (HDACs), resulting effected cell attachment, immune cell immigration, cytokine production, chemotaxis, and the programmed cell death. Therefore, the manipulation of SCFA levels in the intestinal tract by alterations in the microbiota structure can be potentially taken into consideration for cancer treatment/prevention. In the current study, we will explain the most recent findings on the detrimental or protective roles of SFCA (particularly butyrate, propionate, and acetate) in several cancers, including bladder, colon, breast, stomach, liver, lung, pancreas, and prostate cancers.

Contribution of Histone Deacetylases in Prognosis and Therapeutic Management of Cholangiocarcinoma

Cholangiocarcinoma (CCA), a malignant tumor that occurs in the epithelium of the biliary tract, has a very poor prognosis because affected patients are frequently diagnosed at an advanced stage and recurrence after resection is common. Over the last two decades, our understanding of the molecular biology of this malignancy has expanded, and various studies have explored targeted therapy for CCA in order to improve patient survival. The histone acetylation/deacetylation equilibrium is affected in carcinogenesis, leading to altered chromatin structure and therefore changes in gene expression. Understanding the molecular identity of histone deacetylases (HDACs), their cellular interactions and potential role as anticancer agents will help us develop new therapeutic strategies for CCA-affected patients. Furthermore, HDAC inhibitors act on cellular stress response pathways and decrease cancer angiogenesis. Downregulation of pro-angiogenic genes such as vascular endothelial growth factor (VEGF), hypoxia inducible factor-1 (HIF-1), and endothelial nitric oxide synthase (eNOS) inhibit formation of new vessels and can negatively affect the metastatic process. Finally, recent clinical trials prove that administration of both HDAC inhibitors and DNA-targeting chemotherapeutic agents, such as topoisomerase inhibitors, DNA intercalating agents, inhibitors of DNA synthesis, covalently modifying DNA agents, and ionizing radiation, maximizes the anticancer effect by increasing the cytotoxic efficiency of a variety of DNA-damaging anticancer drugs. Therefore, combination therapy of classic chemotherapeutic drugs with HDAC inhibitors can act synergistically for the patients' benefit.

Effect of epigenetic modulation on cancer sphere

Background : Cancer stem cell properties are highly relevant to the biology of treatment-resistant cancers. Epigenetic modification regulates gene expressions by chromatin remodeling during malignant transformation. The aim of this study was to elucidate the possible strategy for cancer stem cells focusing on epigenetic modification. Methods : We made cancer sphere from HepG2 cells, and we added Histone deacetylase (HDAC) inhibitor, valproic acid to cancer sphere. And we compared methylation status and the gene expression between normal HepG2 and cancer sphere groups, and between cancer sphere and sphere with HDAC inhibitor treatment groups. Results : Valproic acid (VPA) cancelled this spheroid formation. In comparison between normal HepG2 and cancer sphere, the number of methylation status changes more than 0.1 of beta level was 826 probes, and we could isolate some epithelial-mesenchymal transition (EMT) related genes. And VPA reduced the expressions of EMT related genes in sphere with RT-PCR. On the other hand, in comparison between cancer sphere and sphere with VPA treatment, we detected 29 probe of methylation status change, and VPA reduced the expressions of Bcl-6 in sphere. Conclusions : HDAC inhibitor affected the methylation status of cancer stem cells. Histone-acetylation might overcome treatmet-resistant cancer through the regulation of cancer stem cell. J. Med. Invest. 67 : 70-74, February, 2020.

Oncobiosis and Microbial Metabolite Signaling in Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma is one of the most lethal cancers in both men and women, with a median five-year survival of around 5%. Therefore, pancreatic adenocarcinoma represents an unmet medical need. Neoplastic diseases, such as pancreatic adenocarcinoma, often are associated with microbiome dysbiosis, termed oncobiosis. In pancreatic adenocarcinoma, the oral, duodenal, ductal, and fecal microbiome become dysbiotic. Furthermore, the pancreas frequently becomes colonized (by Helicobacter pylori and Malassezia, among others). The oncobiomes from long- and short-term survivors of pancreatic adenocarcinoma are different and transplantation of the microbiome from long-term survivors into animal models of pancreatic adenocarcinoma prolongs survival. The oncobiome in pancreatic adenocarcinoma modulates the inflammatory processes that drive carcinogenesis. In this review, we point out that bacterial metabolites (short chain fatty acids, secondary bile acids, polyamines, indole-derivatives, etc.) also have a role in the microbiome-driven pathogenesis of pancreatic adenocarcinoma. Finally, we show that bacterial metabolism and the bacterial metabolome is largely dysregulated in pancreatic adenocarcinoma. The pathogenic role of additional metabolites and metabolic pathways will be identified in the near future, widening the scope of this therapeutically and diagnostically exploitable pathogenic pathway in pancreatic adenocarcinoma.

HDACi mediate UNG2 depletion, dysregulated genomic uracil and altered expression of oncoproteins and tumor suppressors in B- and T-cell lines

BACKGROUND

HDAC inhibitors (HDACi) belong to a new group of chemotherapeutics that are increasingly used in the treatment of lymphocyte-derived malignancies, but their mechanisms of action remain poorly understood. Here we aimed to identify novel protein targets of HDACi in B- and T-lymphoma cell lines and to verify selected candidates across several mammalian cell lines.

METHODS

Jurkat T- and SUDHL5 B-lymphocytes were treated with the HDACi SAHA (vorinostat) prior to SILAC-based quantitative proteome analysis. Selected differentially expressed proteins were verified by targeted mass spectrometry, RT-PCR and western analysis in multiple mammalian cell lines. Genomic uracil was quantified by LC-MS/MS, cell cycle distribution analyzed by flow cytometry and class switch recombination monitored by FACS in murine CH12F3 cells.

RESULTS

SAHA treatment resulted in differential expression of 125 and 89 proteins in Jurkat and SUDHL5, respectively, of which 19 were commonly affected. Among these were several oncoproteins and tumor suppressors previously not reported to be affected by HDACi. Several key enzymes determining the cellular dUTP/dTTP ratio were downregulated and in both cell lines we found robust depletion of UNG2, the major glycosylase in genomic uracil sanitation. UNG2 depletion was accompanied by hyperacetylation and mediated by increased proteasomal degradation independent of cell cycle stage. UNG2 degradation appeared to be ubiquitous and was observed across several mammalian cell lines of different origin and with several HDACis. Loss of UNG2 was accompanied by 30-40% increase in genomic uracil in freely cycling HEK cells and reduced immunoglobulin class-switch recombination in murine CH12F3 cells.

CONCLUSION

We describe several oncoproteins and tumor suppressors previously not reported to be affected by HDACi in previous transcriptome analyses, underscoring the importance of proteome analysis to identify cellular effectors of HDACi treatment. The apparently ubiquitous depletion of UNG2 and PCLAF establishes DNA base excision repair and translesion synthesis as novel pathways affected by HDACi treatment. Dysregulated genomic uracil homeostasis may aid interpretation of HDACi effects in cancer cells and further advance studies on this class of inhibitors in the treatment of APOBEC-expressing tumors, autoimmune disease and HIV-1.

Anticancer Effect of Radix Astragali on Cholangiocarcinoma In Vitro and Its Mechanism via Network Pharmacology

Background

This study used network pharmacology method and cell model to assess the effects of Radix Astragali (RA) on cholangiocarcinoma (CCA) and to predict core targets and molecular mechanisms.

Material/Methods

We performed an in vitro study to assess the effect of RA on CCA using CCK8 assay, the Live-Cell Analysis System, and trypan blue staining. The components and targets of RA were analyzed using the Traditional Chinese Medicine Systems Pharmacology database, and genes associated with CCA were retrieved from the GeneCards and OMIM platforms. Protein–protein interactions were analyzed with the STRING platform. The components–targets–disease network was built by Cytoscape. The TIMER database revealed the expression of core targets with diverse immune infiltration levels. GO and KEGG analyses were performed to identify molecular-biology processes and signaling pathways. The predictions were verified by Western blotting.

Results

Concentration-dependent antitumor activity was confirmed in the cholangiocarcinoma QBC939 cell line treated with RA. RA contained 16 active compounds, with quercetin and kaempferol as the core compounds. The most important biotargets for RA in CCA were caspase 3, MAPK8, MYC, EGFR, and PARP. The TIMER database revealed that the expression of caspase3 and MYC was related with diverse immune infiltration levels of CCA. The results of Western blotting showed RA significantly influenced the expression of the 5 targets that network pharmacology predicted.

Conclusions

RA is an active medicinal material that can be developed into a safe and effective multi-targeted anticancer treatment for CCA.

The synergistic antitumor effect of Huaier combined with 5-Florouracil in human cholangiocarcinoma cells

BACKGROUND

5-Florouracil (5-FU) is a commonly used chemotherapeutic drug for cholangiocarcinoma, whereas it has unsatisfactory effect, and patients often have chemo-resistance to it. The combination of chemotherapeutic agents and traditional Chinese medicine has already exhibited a promising application in oncotherapy. Huaier extract (Huaier) has been used in clinical practice widely, exhibiting good anti-tumor effect. This paper aims to investigate the possibility of combination 5-FU and Huaier as a treatment for cholangiocarcinoma.

METHODS

A series of experiments were performed on the Huh28 cells in vitro, which involved cell proliferation, colony formation, apoptosis, cell cycle, migratory and invasive tests. Besides, western blots were also performed to examine the potential mechanism of 5-FU.

RESULTS

The combination effect (antagonism, synergy or additive) was assessed using Chou-Talalay method. Using the CCK-8 and Colony formation assay, the anti-proliferation effect of 5-FU combined with Huaier was observed. Apoptosis inducing and cell cycle arrest effect of the combination of two drugs were assessed by flow cytometry. To determine the combined treatment on cell immigration and invasion ability, wound healing and Transwell assay were performed. The above experiment results suggest that the combined 5-FU and Huaier, compared with treatment using either drug alone, exhibited stronger effects in anti-proliferation, cycle arrest, apoptosis-induced and anti-metastasis. Further, western blot results reveal that the inhibition of STAT3 and its target genes (e.g. Ki67, Cyclin D1, Bcl-2 and MMP-2) might be set as the potential therapeutic targets. Besides, the inhibition of combination treatment in proteins expression associated with proliferation, apoptosis, cell cycle and metastasis was consistent with that of previous phenotypic experiments.

CONCLUSIONS

Huaier combined with 5-FU exhibited a synergistic anti-tumor effect in Huh28 cell. Furthermore, the mechanisms might be associated with the activation and translocation of STAT3, as well as its downstream genes.

Comparison of Radiosensitization by HDAC Inhibitors CUDC-101 and SAHA in Pancreatic Cancer Cells

Pancreatic cancer has a poor prognosis. New treatment options are urgently required to improve patient outcomes. One promising new class of anticancer drugs are synthetic histone deacetylase inhibitors (HDACi) which modulate chromatin structure and gene expression by blocking histone deacetylation. In this study, we aimed at comparing the in vitro capacities of the HDACi SAHA and CUDC-101 to increase radiosensitivity of human pancreatic tumor cell lines. Therefore, three pancreatic cancer cell lines (Su.86.86, MIA Paca-2, T3M-4) were treated with SAHA (1.5–5 µM) or CUDC-101 (0.25–3 µM) and after 24 h irradiated. Cell proliferation, clonogenic survival and apoptosis was determined. Additionally, cell lysates were investigated for the expression of apoptosis-related proteins. CUDC-101 and SAHA increased the radiation sensitivity of pancreatic tumor cell lines in a dose-dependent manner. This was evidenced by cell proliferation and clonogenic survival. Furthermore, enhanced radiation sensitivity after CUDC-101 or SAHA treatment was confirmed for Su.86.86 and T3M-4 cells in a 3-D microtissue approach. Increased amounts of subG1 cells and diminished full length PARP-1 suggest increased radiation-induced apoptosis after SAHA or CUDC-101 treatment. The comparison of both inhibitors in these assays manifested CUDC-101 as more potent radiosensitizer than SAHA. In line, western blot quantification of the apoptosis-inhibitory proteins XIAP and survivin showed a stronger down-regulation in response to CUDC-101 treatment than after SAHA application. These proteins may contribute to the synergy between HDAC inhibition and radiation response. In conclusion, these preclinical results suggest that treatment with the HDAC inhibitors CUDC-101 or SAHA can enhance radiation-induced cytotoxicity in human pancreatic cells. However, comparison of both inhibitors identified the multi target inhibitor CUDC-101 as more potent radiosensitizer than the HDAC inhibitor SAHA.

Biliary tract cancers: current knowledge, clinical candidates and future challenges

Biliary tract cancers (BTCs) are rare with poor prognosis. Due to the advent of genomic sequencing, new data have emerged regarding the molecular makeup of this disease. To add to the complexity, various subtypes also harbor a varied genetic composition. The commonly mutated genes associated with this cancer are KRAS, EGFR, IDH, FGFR and BAP1. Various clinical studies are looking at targeting these genetic mutations. Another therapeutic area of note is the potential for the use of immunotherapy in patients with BTC. Although BTC may be a result of chronic inflammation, this does not necessarily translate into increased immunogenicity. This literature review discusses the diverse molecular and immune-related pathways in patients with BTC and their potential therapeutic implications.

Synergistic Effect of Forbesione From Garcinia hanburyi in Combination with 5-Fluorouracil on Cholangiocarcinoma

Background: Chemotherapy for advanced cholangiocarcinoma (CCA) is largely ineffective; thus innovative combinations of chemotherapeutic agents and natural compounds represent a promising strategy. This study aimed to investigate the synergistic effects of forbesione combined with 5-fluorouracil (5-FU) in hamster cholangiocarcinoma (Ham-1) cells both in vitro and in vivo. The anti-tumor effects of 5-FU combined with forbesione in vitro were determined using the Sulforhodamine B (SRB) assay and the effects in vivo were assessed in transplanted Ham-1 allograph models. Using ethidium bromide/acridine orange (EB/AO) staining, the morphological changes of apoptotic cells was investigated. The expressions of apoptosis-related molecules after combined treatment with forbesione and 5-FU were determined using real-time RT-PCR and western blot analysis. Forbesione or 5-FU alone inhibited proliferation of Ham-1 cells in a dose-dependent manner and their combination showed a synergistic proliferation inhibitory effect in vitro. In vivo studies, forbesione in combination with 5-FU exhibited greater inhibition of the tumor in the hamster model compared with treatment using either drug alone. Forbesione combined with 5-FU exerted stronger apoptotic induction in Ham-1 cells than did single drug treatment. The combination of drugs strongly suppressed the expression of B-cell lymphoma 2 (Bcl-2) and procaspase-3 while enhancing the expression of p53, Bcl-2-associated X protein (Bax), apoptotic protease activating factor-1 (Apaf-1), caspase-9 and caspase-3, compared with single drug treatments. These results explained the decreased expression of cytokeratin 19 (CK19) positive cells and proliferation cell nuclear antigen (PCNA) positive cells in Ham-1 cell tumor tissues of the treated hamsters. There was no apparent systemic toxicity observed in the treated animals compared with the control groups. Forbesione combined with 5-FU strongly induced apoptosis in Ham-1 cells. The growth inhibitory effect of combined treatment using these two drugs was much greater than treatment with either drug alone, both in vitro and in vivo.

CG200745, an HDAC inhibitor, induces anti-tumour effects in cholangiocarcinoma cell lines via miRNAs targeting the Hippo pathway

Cholangiocarcinoma is a devastating malignancy with fatal complications that exhibits low response and resistance to chemotherapy. Here, we evaluated the anticancer effects of CG200745, a novel histone deacetylase inhibitor, either alone or in combination with standard chemotherapy drugs in cholangiocarcinoma cells. CG200745 dose-dependently reduced the viability of cholangiocarcinoma cells in vitro and decreased tumour volume and weight in a xenograft model. Administering CG200745 along with other chemotherapeutic agents including gemcitabine, 5-fluorouracil (5-FU), cisplatin, oxaliplatin, or gemcitabine plus cisplatin further decreased cholangiocarcinoma cell viability, with a combination index < 1 that indicated synergistic action. CG200745 also enhanced the sensitivity of gemcitabine-resistant cells to gemcitabine and 5-FU, thereby decreasing cell viability and inducing apoptosis. This was accompanied by downregulation of YAP, TEAD4, TGF-β2, SMAD3, NOTCH3, HES5, Axl, and Gas6 and upregulation of the miRNAs miR-22-3p, miR-22-5p, miR-194-5p, miR-194-3p, miR-194-5p, miR-210-3p, and miR-509-3p. The Ingenuity Pathway Analysis revealed that CG200745 mainly targets the Hippo signalling pathway by inducing miR-509-3p expression. Thus, CG200745 inhibits cholangiocarcinoma growth in vitro and in vivo, and acts synergistically when administered in combination with standard chemotherapeutic agents, enabling dose reduction. CG200745 is therefore expected to improve the outcome of cholangiocarcinoma patients who exhibit resistance to conventional therapies.

Inhibition of polypyrimidine tract-binding protein 3 induces apoptosis and cell cycle arrest, and enhances the cytotoxicity of 5- fluorouracil in gastric cancer cells

Background:

Human polypyrimidine tract binding protein 3 (PTBP3) was first discovered in 1999 and has been well characterised as a differentiation regulator. However, its role in human cancer has rarely been reported. Our previous study revealed increased PTBP3 protein level in gastric cancer tissues. Downregulation of PTBP3 suppressed the proliferation and differentiation of gastric cancer cells in vivo.

Methods:

PTBP3 mRNA levels in human gastric cancer and adjuvant non-tumour tissues were detected. Apoptosis and 5-FU effect were determined in PTBP3-silenced gastric cancer cells. Underlying molecular mechanisms were investigated.

Results:

MRNA expression of PTBP3 was upregulated in gastric cancer tissues, especially in those at an advanced stage. PTBP3 silencing led to apoptosis, under which modulation of PTB and thereby switch of Bcl-x pre-mRNA splicing pattern might be an important mechanism. Further research found that inhibition of PTBP3 expression enhanced the chemosensitivity of gastric cancer cells towards 5-FU treatment. This was mediated by reduced expression of histone deacetylase 6 (HDAC6), which further inhibited the phosphorylation of Akt and the expression of thymidylate synthase (TYMS), the critical determinant of 5-FU cytotoxicity.

Conclusions:

PTBP3 might serve as a biomarker of gastric cancer or potential target for anti-cancer therapy.

Next-generation sequencing survey of biliary tract cancer reveals the association between tumor somatic variants and chemotherapy resistance

BACKGROUND

Biliary tract cancers (BTCs) are uncommon and are associated with a dismal prognosis. Combinations of gemcitabine and platinum chemotherapy (gemcitabine and platinum-based therapy [GP]) form the standard approach for treating advanced BTC. To characterize the spectrum of mutations and to identify potential biomarkers for a GP response in BTC, this study evaluated the genomic landscape and assessed whether mutations affecting DNA repair were associated with GP resistance.

METHODS

Pretreatment, formalin-fixed, paraffin-embedded samples from 183 BTC patients treated with GP were analyzed. Cox regression models were used to determine the association between mutations, progression-free survival (PFS), and overall survival (OS).

RESULTS

When genes with an incidence > 10% were considered, no individual gene was independently predictive of a GP response. In patients with unresectable BTC who received GP as their first-line therapy, the joint status of cyclin-dependent kinase inhibitor 2A (CDKN2A), tumor protein 53 (TP53), and AT-rich interaction domain 1A (ARID1A) was associated with PFS (P = .0004) and OS (P ≤ .0001). Patients with mutations in CDKN2A and TP53 were identified as a poor-prognosis cohort with a median PFS of 2.63 months and a median OS of 5.22 months. Patients with mutant ARID1A, regardless of the single-mutation status of TP53 or CDKN2A, had similar outcomes. A patient who exhibited mutations in all 3 genes had a median PFS of 20.37 months, and OS was not reached.

CONCLUSIONS

In the largest exploratory analysis of this kind for BTC, 3 prevalent, mutually exclusive mutations represent distinct patient cohorts. These mutations are prognostic and may represent a predictive biomarker for a GP response. Prospective studies to validate these findings are needed, and they should include the incorporation of therapies that exploit the genomic instability observed with these mutations in BTC. Cancer 2016;122:3657-66. © 2016 American Cancer Society.

Hypoxia-inducible factor-targeting prodrug TOP3 combined with gemcitabine or TS-1 improves pancreatic cancer survival in an orthotopic model

Pancreatic cancer is one of the most lethal digestive system cancers with a 5‐year survival rate of 4–7%. Despite extensive efforts, recent chemotherapeutic regimens have provided only limited benefits to pancreatic cancer patients. Gemcitabine and TS‐1, the current standard‐of‐care chemotherapeutic drugs for treatment of this severe cancer, have a low response rate. Hypoxia is one of the factors contributing to treatment resistance. Specifically, overexpression of hypoxia‐inducible factor, a master transcriptional regulator of cell adaption to hypoxia, is strongly correlated with poor prognosis in many human cancers. TAT‐ODD‐procaspase‐3 (TOP3) is a protein prodrug that is specifically processed and activated in hypoxia‐inducible factor‐active cells in cancers, leading to cell death. Here, we report combination therapies in which TOP3 was combined with gemcitabine or TS‐1. As monotherapy, gemcitabine and TS‐1 showed a limited effect on hypoxic and starved pancreatic cancer cells, whereas co‐treatment with TOP3 successfully overcame this limitation in vitro. Furthermore, combination therapies of TOP3 with these drugs resulted in a significant improvement in survival of orthotopic pancreatic cancer models involving the human pancreatic cancer cell line SUIT‐2. Overall, our study indicates that the combination of TOP3 with current chemotherapeutic drugs can significantly improve treatment outcome, offering a promising new therapeutic option for patients with pancreatic cancer.

Histone deacetylase inhibitor screening identifies HC toxin as the most effective in intrahepatic cholangiocarcinoma cells

Histone deacetylases (HDACs) are highly expressed in intrahepatic cholangiocarcinoma (ICC) and are associated with poor prognosis of these patients. The aim of the present study was to explore the inhibitory effects of HDAC inhibitors on ICC cells and identify effective and sensitive drugs for ICC. Effects of 34 HDAC inhibitors were screened through two rounds of cell viability assays, and HC toxin, a cyclic tetrapeptide first isolated from the secondary metabolite of Helminthosporium carbonum, exhibited an antitumor activity superior to that of the other HDAC inhibitors and gemcitabine. The mechanisms involved in the inhibitory effects of HC toxin on CCLP-1 cells were investigated by cell counting, colony formation assay, cell morphological observation, real-time PCR, western blotting and flow cytometry. It was demonstrated that HC toxin inhibited the cell proliferation and clone formation ability of the CCLP-1 cells. HC toxin increased the acetyl-histone H4 level and this was associated with the inhibitory effect of HC toxin on the CCLP-1 cells. We also found that HC toxin reduced the level of HDAC1 protein in a post-transcriptional manner. Morphological observation showed multiple morphological changes and indicated the possibility of cell differentiation owing to HC toxin. With increasing concentration of HC toxin, the cell cycle was gradually arrested at the G0/G1 stage and the percentage of apoptotic cells increased which was not mainly through the caspase-3-dependent ways. These results indicated that HC toxin was the most effective among the various HDAC inhibitors with multiple functions in the suppression of ICC in vitro. Thus, HC may be a potential chemotherapeutic for ICC.

Chromosome segregation and organization are targets of 5'-Fluorouracil in eukaryotic cells

The antimetabolite 5'-Fluorouracil (5FU) is an analog of uracil commonly employed as a chemotherapeutic agent in the treatment of a range of cancers including colorectal tumors. To assess the cellular effects of 5FU, we performed a genome-wide screening of the haploid deletion library of the eukaryotic model Schizosaccharomyces pombe. Our analysis validated previously characterized drug targets including RNA metabolism, but it also revealed unexpected mechanisms of action associated with chromosome segregation and organization (post-translational histone modification, histone exchange, heterochromatin). Further analysis showed that 5FU affects the heterochromatin structure (decreased levels of histone H3 lysine 9 methylation) and silencing (down-regulation of heterochromatic dg/dh transcripts). To our knowledge, this is the first time that defects in heterochromatin have been correlated with increased cytotoxicity to an anticancer drug. Moreover, the segregation of chromosomes, a process that requires an intact heterochromatin at centromeres, was impaired after drug exposure. These defects could be related to the induction of genes involved in chromatid cohesion and kinetochore assembly. Interestingly, we also observed that thiabendazole, a microtubule-destabilizing agent, synergistically enhanced the cytotoxic effects of 5FU. These findings point to new targets and drug combinations that could potentiate the effectiveness of 5FU-based treatments.

Epigenetic perspectives on cancer chemotherapy response

Epigenetic programs are now widely recognized as being critical to the biological processes of cancer genesis. However, it has not been comprehensively understood how and to what degree they can influence anticancer drugs responses. The development of drugs targeting epigenetic regulation has generated great enthusiasm, with a growing number in clinical development. We highlight here that epigenetic modifications can be involved in the regulation of genes responsible for the absorption, distribution, metabolism and excretion of drugs and for the pathological progression of cancer, thereby affecting anticancer drug responses. The major epigenetic regulatory mechanisms are reviewed, including DNA methylation, miRNA regulation and histone modification, with the aim of promoting rational use of anticancer drugs in the clinic and epigenetic drug development.

Therapeutic potential of histone deacetylase inhibitors in pancreatic cancer

Pancreatic cancer is a devastating disease with a dismal prognosis. Surgical resection is the only curative option but is heavily hampered by delayed diagnosis. Due to few therapeutic treatments available, novel and efficacious therapy is urgently needed. Histone deacetylase inhibitors (HDACIs) are emerging as a prominent class of therapeutic agents for pancreatic cancer and have exhibited significant anticancer potential with negligible toxicity in preclinical studies. Clinical evaluations of HDACIs are currently underway. HDACIs as monotherapy in solid tumors have proven less effective than hematological malignancies, the combination of HDACIs with other anticancer agents have been assessed for advanced pancreatic cancer. In this review, we describe the molecular mechanism underpin the anticancer effect of HDACIs in pancreatic cancer and summarize the recent advances in the rationale for the combination strategies incorporating HDACIs. In addition, we discuss the importance of identifying predictors of response to HDACI-based therapy.

Epigenetic targeting in pancreatic cancer

The prognosis of pancreatic cancer patients is very poor, with a 5-year survival of less than 6%. Therefore, there is an urgent need for new therapeutic options in pancreatic cancer. In the past years it became evident that deregulation of epigenetic mechanisms plays an important role in pancreatic carcinogenesis. This review focuses on the exploitation of drugs that alter histone modifications, DNA methylation and microRNA expression as options for the treatment of pancreatic cancer.

Histone deacetylases and their inhibitors as potential therapeutic drugs for cholangiocarcinoma - cell line findings

Histone deacetylation mediated by histone deacetylases (HDACs) has been reported as one of the epigenetic mechanisms associated with tumorigenesis. The poor responsiveness of anticancer drugs found with cholangiocarcinoma (CCA) leads to short survival rate. We aimed to investigate mRNA expression of HDACs class I and II, and the effect of HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA) and valproic acid (VPA), in CCA in vitro. Expression of HDACs was studied in CCA cell lines (M213, M214 and KKU-100) and an immortal cholangiocyte (MMNK1) by semi-quantitative reverse transcription-PCR. SAHA and VPA, as well as a classical chemotherapeutic drug 5-fluorouracil (5-FU) were used in this study. Cell proliferation was determined by sulforhodamine assay. IC50 and IC20 were then analyzed for each agent and cell line. Moreover, synergistic potential of VPA or SAHA in combination with 5-FU at subtoxic dose (IC20) of each agent was also evaluated. Statistic difference of HDACs expression or cell proliferation in each experimental condition was analyzed by Student's t-test. The result demonstrated that HDACs were expressed in all studied cell types. Both SAHA and VPA inhibited cell proliferation in a dose-dependent manner. Interestingly, KKU-100 which was less sensitive to classical chemotherapeutic 5-FU was highly sensitive to HDAC inhibitors. Simultaneous combination of subtoxic doses of HDAC inhibitors and 5-FU significantly inhibited cell proliferation in CCA cell lines compared to single agent treatment (P ≤ 0.01), while sequentially combined treatments were less effective. The present study showed inhibitory effects of HDACIs on cell proliferation in CCA cell lines, with synergistic antitumor potential demonstrated by simultaneous combination of VPA or SAHA with 5-FU, suggesting a novel alternative therapeutic strategy in effective treatment of CCA.

The anti-tumor effect of HDAC inhibition in a human pancreas cancer model is significantly improved by the simultaneous inhibition of cyclooxygenase 2

Pancreatic ductal adenocarcinoma is the fourth leading cause of cancer death worldwide, with no satisfactory treatment to date. In this study, we tested whether the combined inhibition of cyclooxygenase-2 (COX-2) and class I histone deacetylase (HDAC) may results in a better control of pancreatic ductal adenocarcinoma. The impact of the concomitant HDAC and COX-2 inhibition on cell growth, apoptosis and cell cycle was assessed first in vitro on human pancreas BxPC-3, PANC-1 or CFPAC-1 cells treated with chemical inhibitors (SAHA, MS-275 and celecoxib) or HDAC1/2/3/7 siRNA. To test the potential antitumoral activity of this combination in vivo, we have developed and characterized, a refined chick chorioallantoic membrane tumor model that histologically and proteomically mimics human pancreatic ductal adenocarcinoma. The combination of HDAC1/3 and COX-2 inhibition significantly impaired proliferation of BxPC-3 cells in vitro and stalled entirely the BxPC-3 cells tumor growth onto the chorioallantoic membrane in vivo. The combination was more effective than either drug used alone. Consistently, we showed that both HDAC1 and HDAC3 inhibition induced the expression of COX-2 via the NF-kB pathway. Our data demonstrate, for the first time in a Pancreatic Ductal Adenocarcinoma (PDAC) model, a significant action of HDAC and COX-2 inhibitors on cancer cell growth, which sets the basis for the development of potentially effective new combinatory therapies for pancreatic ductal adenocarcinoma patients.

Histone deacetylases as targets for treatment of multiple diseases

HDACs (histone deacetylases) are a group of enzymes that deacetylate histones as well as non-histone proteins. They are known as modulators of gene transcription and are associated with proliferation and differentiation of a variety of cell types and the pathogenesis of some diseases. Recently, HDACs have come to be considered crucial targets in various diseases, including cancer, interstitial fibrosis, autoimmune and inflammatory diseases, and metabolic disorders. Pharmacological inhibitors of HDACs have been used or tested to treat those diseases. In the present review, we will examine the application of HDAC inhibitors in a variety of diseases with the focus on their effects of anti-cancer, fibrosis, anti-inflammatory, immunomodulatory activity and regulating metabolic disorders.