A Histone Deacetylase Inhibitor Suppresses Epithelial-Mesenchymal Transition and Attenuates Chemoresistance in Biliary Tract Cancer

Epithelial-Mesenchymal Plasticity and Epigenetic Heterogeneity in Cancer

The tumor microenvironment comprises various cell types and experiences dynamic alterations in physical and mechanical properties as cancer progresses. Intratumoral heterogeneity is associated with poor prognosis and poses therapeutic challenges, and recent studies have begun to identify the cellular mechanisms that contribute to phenotypic diversity within tumors. This review will describe epithelial-mesenchymal (E/M) plasticity and its contribution to phenotypic heterogeneity in tumors as well as how epigenetic factors, such as histone modifications, histone modifying enzymes, DNA methylation, and chromatin remodeling, regulate and maintain E/M phenotypes. This review will also report how mechanical properties vary across tumors and regulate epigenetic modifications and E/M plasticity. Finally, it highlights how intratumoral heterogeneity impacts therapeutic efficacy and provides potential therapeutic targets to improve cancer treatments.

The combination of gemcitabine plus an anti-FGFR inhibitor can have a synergistic antitumor effect on FGF-activating cholangiocarcinoma

Anti-FGFR treatment for cholangiocarcinoma (CCA) with fibroblast growth factor receptor (FGFR) alteration is a promising treatment option. Since the antitumor mechanisms of anti-FGFR inhibitors and conventional cytotoxic drugs differ, synergistic effects can be possible. This study aimed to evaluate the efficacy of the combined administration of gemcitabine (GEM) and pemigatinib in CCA cells with FGFR2 alterations. To simulate the treatment for patients with 3 kinds of CCA, chemonaïve CCA with activation of the FGF pathway, chemo-resistant CCA with activation of the FGF pathway, and CCA without FGF pathway activation (as controls), we evaluated 3 different CCA cell lines, CCLP-1 (with a FGFR2 fusion mutation), CCLP-GR (GEM-resistant cells established from CCLP-1), and HuCCT1 (without FGFR mutations). There was no significant difference between CCLP-1 and HuCCT1 in GEM suspensibility (IC50 = 19.3, 22.6 mg/dl, p = 0.1187), and the drug sensitivity to pemigatinib did not differ between CCLP-1 and CCLP-GR (IC50 = 7.18,7.60 nM, p = 0.3089). Interestingly, only CCLP-1 showed a synergistic effect with combination therapy consisting of GEM plus pemigatinib in vitro and in vivo. In a comparison of the reaction to GEM exposure, only CCLP-1 cells showed an increase in the activation of downstream proteins in the FGF pathway, especially FRS2 and ERK. In association with this reaction, cell cycle and mitosis were increased with GEM exposure in CCLP-1, but HuCCT1/CCLP-GR did not show this reaction. Our results suggested that combination therapy with GEM plus pemigatinib is a promising treatment for chemonaïve patients with CCA with activation of the FGF pathway.

Targeting histone deacetylase-3 blocked epithelial-mesenchymal plasticity and metastatic dissemination in gastric cancer

BACKGROUND AND PURPOSE

Histone deacetylase (HDAC) inhibitors (HDIs) can modulate the epithelial-mesenchymal transition (EMT) progression and inhibit the migration and invasion of cancer cells. Emerging as a novel class of anti-cancer drugs, HDIs are attracted much attention in the field of drug discovery. This study aimed to discern the underlying mechanisms of Honokiol in preventing the metastatic dissemination of gastric cancer cells by inhibiting HDAC3 activity/expression.

EXPERIMENTAL APPROACH

Clinical pathological analysis was performed to determine the relationship between HDAC3 and tumor progression. The effects of Honokiol on pharmacological characterization, functional, transcriptional activities, organelle structure changes, and molecular signaling were analyzed using binding assays, differential scanning calorimetry, luciferase reporter assay, HDAC3 activity, ER stress response element activity, transmission electron microscopy, immune-blotting, and Wnt/β-catenin activity assays. The in vivo effects of Honokiol on peritoneal dissemination were determined by a mouse model and detected by PET/CT tomography.

KEY RESULTS

HDAC3 over-expression was correlated with poor prognosis. Honokiol significantly abolished HDAC3 activity (Y298) via inhibition of NFκBp65/CEBPβ signaling, which could be reversed by the over-expression of plasmids of NFκBp65/CEBPβ. Treatments with 4-phenylbutyric acid (a chemical chaperone) and calpain-2 gene silencing inhibited Honokiol-inhibited NFκBp65/CEBPβ activation. Honokiol increased ER stress markers and inhibited EMT-associated epithelial markers, but decreased Wnt/β-catenin activity. Suppression of HDAC3 by both Honokiol and HDAC3 gene silencing decreased cell migration and invasion in vitro and metastasis in vivo.

CONCLUSIONS AND IMPLICATIONS

Honokiol acts by suppressing HDAC3-mediated EMT and metastatic signaling. By prohibiting HDAC3, metastatic dissemination of gastric cancer may be blocked. Conceptual model showing the working hypothesis on the interaction among Honokiol, HDAC3, and ER stress in the peritoneal dissemination of gastric cancer. Honokiol targeting HDAC3 by ER stress cascade and mitigating the peritoneal spread of gastric cancer. Honokiol-induced ER stress-activated calpain activity targeted HDAC3 and blocked Tyr298 phosphorylation, subsequently blocked cooperating with EMT transcription factors and cancer progression. The present study provides evidence to demonstrate that HDAC3 is a positive regulator of EMT and metastatic growth of gastric cancer cells. The findings here imply that overexpressed HDAC3 is a potential therapeutic target for honokiol to reverse EMT and prevent gastric cancer migration, invasion, and metastatic dissemination. • Honokiol significantly abolished HDAC3 activity on catalytic tyrosine 298 residue site. In addition, Honokiol-induced ER stress markedly inhibited HDAC3 expression via inhibition of NFκBp65/CEBPβ signaling. • HDAC3, which is a positive regulator of metastatic gastric cancer cell growth, can be significantly inhibited by Honokiol. • Opportunities for HDAC3 inhibition may be a potential therapeutic target for preventing gastric cancer metastatic dissemination.

Anti-proliferative, pro-apototic and anti-migratory properties of HDAC inhibitor PXD-101 on osteosarcoma cell lines

The therapeutic strategies for osteosarcoma involve both surgical approach and chemotherapy, but the identification of new therapeutic targets is particularly necessary in patients with local chemo-resistance, recurrence and lung metastases. The role of epigenetic regulation in osteosarcoma is largely unknown. Thus, in this study we disclosed the effects of histone deacetylase inhibitor drug PXD-101 on human osteosarcoma (OS) cell lines with different aggressiveness, including Saos-2, HOS and 143B cell lines. XTT assays revealed that treatment of Saos-2, HOS and 143B cells with PXD-101 decreased cell viability in a concentration-dependent manner. Fluorescence-activated cell sorting (FACS) analysis showed that PXD-101 inhibited proliferation and induced cell apoptosis. Wound healing assay indicated that PXD-101 inhibited migration of osteosarcoma cells. Real-Time RT-qPCR and protein analysis highlighted reduced expression of Runx2, Osterix and Mad2, probably due to Cyclin B1 inhibition by PXD-101 treatment. To our knowledge, this is the first study that characterized the anti-tumoral effect of PXD-101 in OS cells, suggesting a potential new therapeutic approach in osteosarcoma patients.

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.

ACAT-1-Regulated Cholesteryl Ester Accumulation Modulates Gemcitabine Resistance in Biliary Tract Cancer

BACKGROUND

Biliary tract cancer (BTC) has few choices of chemotherapy, including gemcitabine, therefore exploring the mechanisms of gemcitabine resistance is important. We focused on lipid metabolism because biliary tract epithelial cells are essential in cholesterol and bile acid metabolism and the messenger RNA (mRNA) microarray analysis showed high acyl coenzyme A: cholesterol acyltransferase 1 (ACAT-1) expression in BTC gemcitabine-resistant (GR) cell lines. We hypothesized that aberrant accumulation of cholesteryl ester (CE) regulated by ACAT-1 could modulate GR in BTC.

METHODS

CE accumulations were measured in human BTC cell lines, and the relationships between CE levels, ACAT-1 expressions, and gemcitabine sensitivity were analyzed. We performed a small-interfering RNA (siRNA)-mediated knockdown and biochemical inhibition of ACAT-1 in BTC cell lines and alterations of gemcitabine sensitivity were evaluated. To evaluate the clinical significance of ACAT-1 in regard to GR, immunohistochemistry was performed and ACAT-1 expressions were analyzed in resected BTC specimens.

RESULTS

CE levels were correlated with ACAT-1 expressions and GR in four human BTC cell lines. siRNA-mediated knockdown of ACAT-1 in two independent GR cell clones as well as ACAT-1 inhibitor treatment significantly increased gemcitabine sensitivity; knockdown of ACAT-1: 5.63- and 8.02-fold; ACAT-1 inhibitor: 8.75- and 9.13-fold, respectively. ACAT-1 expression in resected BTC specimens revealed that the disease-free survival of the ACAT-1 low-intensity group (median 2.3 years) had a significantly better outcome than that of the ACAT-1 high-intensity group (median 1.1 years) under gemcitabine treatment after surgery (*p < 0.05).

CONCLUSIONS

Our findings suggest that CE and ACAT-1 might be a novel therapeutic target for GR in BTC.

Shooting at Moving and Hidden Targets-Tumour Cell Plasticity and the Notch Signalling Pathway in Head and Neck Squamous Cell Carcinomas

Head and Neck Squamous Cell Carcinoma (HNSCC) is often aggressive, with poor response to current therapies in approximately 40-50% of the patients. Current therapies are restricted to operation and irradiation, often combined with a small number of standard-of-care chemotherapeutic drugs, preferentially for advanced tumour patients. Only very recently, newer targeted therapies have entered the clinics, including Cetuximab, which targets the EGF receptor (EGFR), and several immune checkpoint inhibitors targeting the immune receptor PD-1 and its ligand PD-L1. HNSCC tumour tissues are characterized by a high degree of intra-tumour heterogeneity (ITH), and non-genetic alterations that may affect both non-transformed cells, such as cancer-associated fibroblasts (CAFs), and transformed carcinoma cells. This very high degree of heterogeneity likely contributes to acquired drug resistance, tumour dormancy, relapse, and distant or lymph node metastasis. ITH, in turn, is likely promoted by pronounced tumour cell plasticity, which manifests in highly dynamic and reversible phenomena such as of partial or hybrid forms of epithelial-to-mesenchymal transition (EMT), and enhanced tumour stemness. Stemness and tumour cell plasticity are strongly promoted by Notch signalling, which remains poorly understood especially in HNSCC. Here, we aim to elucidate how Notch signal may act both as a tumour suppressor and proto-oncogenic, probably during different stages of tumour cell initiation and progression. Notch signalling also interacts with numerous other signalling pathways, that may also have a decisive impact on tumour cell plasticity, acquired radio/chemoresistance, and metastatic progression of HNSCC. We outline the current stage of research related to Notch signalling, and how this pathway may be intricately interconnected with other, druggable targets and signalling mechanisms in HNSCC.

Aspects of the Epigenetic Regulation of EMT Related to Cancer Metastasis

Epithelial to mesenchymal transition (EMT) occurs during the pathological process associated with tumor progression and is considered to influence and promote the metastatic cascade. Characterized by loss of cell adhesion and apex base polarity, EMT enhances cell motility and metastasis. The key markers of the epithelial to mesenchymal transition are proteins characteristic of the epithelial phenotype, e.g., E-cadherin, cytokeratins, occludin, or desmoplakin, the concentration and activity of which are reduced during this process. On the other hand, as a result of acquiring the characteristics of mesenchymal cells, an increased amount of N-cadherin, vimentin, fibronectin, or vitronectin is observed. Importantly, epithelial cells undergo partial EMT where some of the cells show both epithelial and mesenchymal characteristics. The significant influence of epigenetic regulatory mechanisms is observed in the gene expression involved in EMT. Among the epigenetic modifications accompanying incorrect genetic reprogramming in cancer are changes in the level of DNA methylation within the CpG islands and posttranslational covalent changes of histone proteins. All observed modifications, which are stable but reversible changes, affect the level of gene expression leading to the development and progression of the disease, and consequently affect the uncontrolled growth of the population of cancer cells.

Histone deacetylase 1 facilitates aerobic glycolysis and growth of endometrial cancer

The deregulation of histone deacetylase 1 (HDAC1) is reportedly involved in the progression of several cancer types. However, its function in endometrial cancer remains unknown. The aim of the present study was to clarify the role of HDAC1 in aerobic glycolysis and the progression of endometrial cancer. Lentiviral vector transfection was used to up- and downregulate HDAC1 expression in HEC-1-A endometrial cancer cells. The effects of HDAC1 on cellular proliferation, apoptosis, migration, invasiveness and tumorigenesis were determined by CCK-8, flow cytometry, wound-healing, transwell chamber and in vivo tumor formation experiments, respectively. HDAC1 level was significantly increased in endometrial cancer tissues and cells, and its high expression was associated with advanced clinicopathological progression. HEC-1-A cell proliferation, invasiveness, migration and tumorigenesis were enhanced, and apoptosis was inhibited when HDAC1 was overexpressed. Moreover, upregulation of HDAC1 significantly promoted the epithelial-mesenchymal transition of HEC-1-A cells, and increased glucose consumption, lactate secretion and ATP levels. Collectively, the present study revealed that HDAC1 promoted the aerobic glycolysis and progression of endometrial cancer, which may provide a potential target for endometrial cancer treatment.

Silver Nanoparticles Modulate the Epithelial-to-Mesenchymal Transition in Estrogen-Dependent Breast Cancer Cells In Vitro

Silver nanoparticles (AgNPs) are frequently detected in many convenience goods, such as cosmetics, that are applied directly to the skin. AgNPs accumulated in cells can modulate a wide range of molecular pathways, causing direct changes in cells. The aim of this study is to assess the capability of AgNPs to modulate the metastasis of breast cancer cells through the induction of epithelial-to-mesenchymal transition (EMT). The effect of the AgNPs on MCF-7 cells was investigated via the sulforhodamine B method, the wound healing test, generation of reactive oxygen species (ROS), the standard cytofluorimetric method of measuring the cell cycle, and the expression of EMT marker proteins and the MTA3 protein via Western blot. To fulfill the results, calcium flux and HDAC activity were measured. Additionally, mitochondrial membrane potential was measured to assess the direct impact of AgNPs on mitochondria. The results indicated that the MCF-7 cells are resistant to the cytotoxic effect of AgNPs and have higher mobility than the control cells. Treatment with AgNPs induced a generation of ROS; however, it did not affect the cell cycle but modulated the expression of EMT marker proteins and the MTA3 protein. Mitochondrial membrane potential and calcium flux were not altered; however, the AgNPs did modulate the total HDAC activity. The presented data support our hypothesis that AgNPs modulate the metastasis of MCF-7 cells through the EMT pathway. These results suggest that AgNPs, by inducing reactive oxygen species generation, alter the metabolism of breast cancer cells and trigger several pathways related to metastasis.

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.

Suppressing effects of green tea extract and Epigallocatechin-3-gallate (EGCG) on TGF-β- induced Epithelial-to-mesenchymal transition via ROS/Smad signaling in human cervical cancer cells

BACKGROUND

Transforming growth factor-β (TGF-β)-induced Epithelial-to-mesenchymal transition (EMT) process is a fundamental target for preventing cervical cancer cells' progression and invasion. Green tea and its principal active substance, Epigallocatechin-3-gallate (EGCG), demonstrate anti-tumor activities in various tumor cells.

METHODS

The cell viability of two cervical cancer cell lines, Hela and SiHa, in the experimental groups was examined employing the MTT method, and ROS generation was probed applying 2',7'-dichlorofluorescein diacetate-based assay. The Smad signaling and EMT process was evaluated utilizing western blot analysis and quantitative real-time polymerase chain reaction (qRT-PCR). Chromatin immunoprecipitation (ChIP) and Smad binding element (SBE)-luciferase assays were employed to measure Smad-DNA interaction and Smad transcriptional activity, respectively.

RESULTS

EGCG (0-100 μmol/L) and green tea extract (0-250 μg/ml) suppressed the viability of cancer cells in a dose-dependent manner (p < 0.01). Our conclusions affirmed that pre-incubation with green tea extract (80 μg/ml) and EGCG (60 μmol/L) significantly reversed the impacts of TGF-β in Hela and SiHa cells by decreasing Vimentin, ZEB, Slug, Snail, and Twist and increasing E-cadherin expression. The molecular mechanism of green tea extract and EGCG for TGF-β-induced EMT inhibition interfered with ROS generation and Smad signaling. Green tea extract and EGCG could significantly decrease ROS levels, the phosphorylation of Smad2/3, the translocation, DNA binding, and activity of Smads in cervical cancer cell lines treated with TGF-β1 (p < 0.01).

CONCLUSION

EGCG and green tea extract suppressed TGF-β-induced EMT in Hela and SiHa cells, and the underlying molecular mechanism may be related to the ROS generation and Smad signaling pathway.

Acetylation of KLF5 maintains EMT and tumorigenicity to cause chemoresistant bone metastasis in prostate cancer

Advanced prostate cancer (PCa) often develops bone metastasis, for which therapies are very limited and the underlying mechanisms are poorly understood. We report that bone-borne TGF-β induces the acetylation of transcription factor KLF5 in PCa bone metastases, and acetylated KLF5 (Ac-KLF5) causes osteoclastogenesis and bone metastatic lesions by activating CXCR4, which leads to IL-11 secretion, and stimulating SHH/IL-6 paracrine signaling. While essential for maintaining the mesenchymal phenotype and tumorigenicity, Ac-KLF5 also causes resistance to docetaxel in tumors and bone metastases, which is overcome by targeting CXCR4 with FDA-approved plerixafor. Establishing a mechanism for bone metastasis and chemoresistance in PCa, these findings provide a rationale for treating chemoresistant bone metastasis of PCa with inhibitors of Ac-KLF5/CXCR4 signaling.

Heterogeneity of Treg/Th17 According to Cancer Progression and Modification in Biliary Tract Cancers via Self-Producing Cytokines

BACKGROUND/AIM

We previously demonstrated that inflammatory cytokine interleukin-6 (IL-6) was produced during cancer progression, worked together with transforming growth factor-beta 1 (TGF-β1), and induced the epithelial-mesenchymal transition (EMT) with chemo-resistance against gemcitabine (GR) at the invasion front of biliary tract cancers (BTCs). However, the significance of cytokine-induced T cell accumulation at the tumor microenvironment in biliary tract cancer (BTC) is not well understood. Because these cytokines (IL-6 and TGF-β1) are able to differentiate naïve T cells into Foxp3-expressing T cells (Tregs) and/or IL-17-producing T helper 17 (Th17) cells, we investigated the relationship between heterogeneous, cancer-producing cytokines and T cell differentiation.

METHODS

In total, 127 curative resected specimens from patients with BTCs at Osaka University Hospital between 2000 and 2012 were evaluated for IL-6, TGF-β1, Tregs, and Th17 cells by immunohistochemistry. The ability of BTC-GR cells to undergo T cell differentiation was investigated in vitro.

RESULTS

Tregs accumulated at the tumor center and Th17 cells accumulated at the invasion front during cancer progression and/or metastasis; each signaled poor prognosis. Treg accumulation was related to TGF-β1 expression by cancer cells, and Th17 cell accumulation was related to IL-6 expression by cancer cells, in resected specimens; this was confirmed in vitro. Compared with parent cells, GR cells produced IL-6 but not TGF-β1 in a time-dependent manner, had EMT features, and induced T cell differentiation to Th17 cells but not Tregs.

CONCLUSION

Cytokines produced by cancer cells (IL-6 and TGF-β1) induced heterogeneity of Tregs and Th17 cells in the tumor microenvironment, supporting progression of BTC.

A novel HDAC1 inhibitor, CBUD‑1001, exerts anticancer effects by modulating the apoptosis and EMT of colorectal cancer cells

Colorectal cancer (CRC) is one of the most commonly diagnosed malignancies and is a leading cause of cancer‑related mortality worldwide. Histone deacetylases (HDACs) are a class of enzymes responsible for the epigenetic regulation of gene expression. Some HDAC inhibitors have been shown to be efficient agents for cancer treatment. The aim of the present study was to discover a novel, potent HDAC inhibitor and demonstrate its anticancer effect and molecular mechanisms in CRC cells. A novel fluorinated aminophenyl‑benzamide‑based compound, CBUD‑1001, was designed to specifically target HDAC1, and it was then synthesized and evaluated. CBUD‑1001 exerted a potent inhibitory effect on HDAC enzyme activity and exhibited anticancer potency against CRC cell lines. Molecular docking analysis rationalized the high potency of CBUD‑1001 by validating its conformation in the HDAC active site. Further investigation using CRC cells demonstrated that CBUD‑1001 inhibited HDAC activity by hyper‑acetylating histones H3 and H4, and it exerted an apoptotic effect by activating a mitochondrial‑dependent pathway. Of note, it was found that CBUD‑1001 attenuates the cell motility of CRC cells by downregulating the EMT signaling pathway. Thus, CBUD‑1001 may prove to be a promising novel drug candidate for CRC therapy.

Small Ones to Fight a Big Problem-Intervention of Cancer Metastasis by Small Molecules

Metastasis represents the most lethal attribute of cancer and critically limits successful therapies in many tumor entities. The clinical need is defined by the fact that all cancer patients, who have or who will develop distant metastasis, will experience shorter survival. Thus, the ultimate goal in cancer therapy is the restriction of solid cancer metastasis by novel molecularly targeted small molecule based therapies. Biomarkers identifying cancer patients at high risk for metastasis and simultaneously acting as key drivers for metastasis are extremely desired. Clinical interventions targeting these key molecules will result in high efficiency in metastasis intervention. In result of this, personalized tailored interventions for restriction and prevention of cancer progression and metastasis will improve patient survival. This review defines crucial biological steps of the metastatic cascade, such as cell dissemination, migration and invasion as well as the action of metastasis suppressors. Targeting these biological steps with tailored therapeutic strategies of intervention or even prevention of metastasis using a wide range of small molecules will be discussed.

Cancer Stem Cells as a Potential Target to Overcome Multidrug Resistance

Multidrug resistance (MDR), which is a significant impediment to the success of cancer chemotherapy, is attributable to various defensive mechanisms in cancer. Initially, overexpression of ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) was considered the most important mechanism for drug resistance; hence, many investigators for a long time focused on the development of specific ABC transporter inhibitors. However, to date their efforts have failed to develop a clinically applicable drug, leaving only a number of problems. The concept of cancer stem cells (CSCs) has provided new directions for both cancer and MDR research. MDR is known to be one of the most important features of CSCs and thus plays a crucial role in cancer recurrence and exacerbation. Therefore, in recent years, research targeting CSCs has been increasing rapidly in search of an effective cancer treatment. Here, we review the drugs that have been studied and developed to overcome MDR and CSCs, and discuss the limitations and future perspectives.

The Prognostic Impact of Leucine-Rich α-2-Glycoprotein-1 in Cholangiocarcinoma and Its Association With the IL-6/TGF-β1 Axis

BACKGROUND

Leucine-rich α-2-glycoprotein-1 (LRG) has been found to participate in the development of various cancers through its involvement in TGF-β1-induced epithelial-mesenchymal transition (EMT) and/or angiogenesis and can be induced by inflammatory cytokines, such as IL-6. As we previously showed the implication of IL-6/TGF-β axis in EMT of cholangiocarcinoma cells, we herein explored the prognostic impact of LRG in postoperative intrahepatic cholangiocarcinoma (ICC) and assessed the association between tumor LRG and factors such as TGF-β1, IL-6, and the tumor microvessel density.

METHODS

We determined the expression of LRG, IL-6, TGF-β1, and CD31 in cancer tissues from 50 ICC patients by immunohistochemistry and analyzed their association with the prognosis.

RESULTS

The LRG expression was closely associated with recurrence-free survival (RFS) and overall survival (OS) in postoperative ICC. A multivariate Cox regression model indicated that LRG as an independently associated with poor RFS (hazard ratio = 2.4339, P = 0.0354) and OS (hazard ratio = 2.8892, P = 0.0268). The LRG expression was significantly associated with the expression of TGF-β1 (P = 0.0003) and IL-6 (P = 0.0164).

CONCLUSIONS

The upregulation of LRG in tumors was an independent prognostic factor in patients with postoperative ICC. LRG was closely associated with the TGF-β1 expression and seems to be an important member of the IL-6/TGF-β1 axis.

TGFB1-induced autophagy affects the pattern of pancreatic cancer progression in distinct ways depending on SMAD4 status

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies. Given that macroautophagy/autophagy activation is prevalent in PDAC, the dual roles of autophagy could be involved in PDAC heterogeneity. In this work, we demonstrated that TGFB1 induced autophagic flux through SMAD4-dependent or SMAD4-independent pathways based on a distinct genetic context. In SMAD4-positive PDAC cells, TGFB1-induced autophagy promoted proliferation and inhibited migration by decreasing the nuclear translocation of SMAD4. Conversely, TGFB1-induced autophagy inhibited proliferation and promoted migration in SMAD4-negative cells through the regulation of MAPK/ERK activation. TGFB1 expression also positively correlated with LC3B expression in PDAC specimens. A high level of LC3B was associated with unfavorable overall survival (OS) and disease-free survival (DFS) in SMAD4-negative PDAC patients, although LC3B could not predict OS and DFS for the 110 PDAC patients. Thus, TGFB1-induced autophagy contributed to the different patterns of PDAC progression. This knowledge can aid in improving our understanding of the molecular classification of PDAC and might guide the development of therapeutic strategies for PDAC, especially for SMAD4-negative PDAC.Abbreviations: CDH1: cadherin 1; CDH2: cadherin 2; CI: combination index; CQ: chloroquine; DFS: disease-free survival; EMT: epithelial-to-mesenchymal transition; ERK: extracellular signal-regulated protein kinase; GFP: green fluorescent protein; IHC: immunohistochemistry; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAPK: mitogen-activated protein kinase; OS: overall survival; PBS: phosphate-buffered saline; PDAC: pancreatic ductal adenocarcinoma; RAP: rapamycin; RFP: red fluorescent protein; RT: room temperature; shRNA: short-hairpin RNA; SQSTM1: sequestosome 1; TCGA: The Cancer Genome Atlas; TEM: transmission electron microscopy; TGFB1: transforming growth factor beta 1; TMA: tissue microarray.

Impact of CD36 on Chemoresistance in Pancreatic Ductal Adenocarcinoma

BACKGROUND

CD36, a multi-ligand scavenger receptor, has been associated with several cancers. Many studies have revealed that CD36 contributed to cancer malignancy. This study aimed to reveal the function of CD36 expression in pancreatic ductal adenocarcinoma (PDAC).

METHODS

CD36 expression was characterized using immunohistochemistry in 95 clinical specimens resected from patients with PDAC. We divided patients into two groups, with different CD36 expression levels, and analyzed and compared their prognoses. CD36 expression was also assessed in PDAC cell lines. Gemcitabine-resistant (GR) PDAC cell lines were transfected with small interfering RNA (siRNA) that specifically targeted CD36 to evaluate chemoresistance and apoptosis.

RESULTS

In resected PDAC samples, CD36 expression was significantly correlated with microinvasion into the venous system (p = 0.0284). Patients with high CD36 expression had significantly lower overall survival (OS) and recurrence-free survival (RFS) rates than patients with low expression; thus, CD36 was an independent prognostic factor for OS and RFS. In subgroup analyses, CD36 was an independent risk factor for OS and RFS in 59 patients treated with gemcitabine adjuvant chemotherapy. CD36 expression was upregulated in PDAC-GR cell lines compared with the PDAC parent cell line. Transduction with siRNA downregulated CD36, which reduced PDAC cell resistance to gemcitabine and inhibited anti-apoptosis proteins.

CONCLUSION

CD36 expression influenced gemcitabine resistance by regulating anti-apoptosis proteins. High CD36 expression was a significant, unfavorable prognostic factor in PDAC. Anti-CD36 treatment might serve as an optional treatment for lowering resistance to gemcitabine.

Metabolic Plasticity and Epithelial-Mesenchymal Transition

A major transcriptional and phenotypic reprogramming event during development is the establishment of the mesodermal layer from the ectoderm through epithelial-mesenchymal transition (EMT). EMT is employed in subsequent developmental events, and also in many physiological and pathological processes, such as the dissemination of cancer cells through metastasis, as a reversible transition between epithelial and mesenchymal states. The remarkable phenotypic remodeling accompanying these transitions is driven by characteristic transcription factors whose activities and/or activation depend upon signaling cues and co-factors, including intermediary metabolites. In this review, we summarize salient metabolic features that enable or instigate these transitions, as well as adaptations undergone by cells to meet the metabolic requirements of their new states, with an emphasis on the roles played by the metabolic regulation of epigenetic modifications, notably methylation and acetylation.

Implication for Cancer Stem Cells in Solid Cancer Chemo-Resistance: Promising Therapeutic Strategies Based on the Use of HDAC Inhibitors

Resistance to therapy in patients with solid cancers represents a daunting challenge that must be addressed. Indeed, current strategies are still not effective in the majority of patients; which has resulted in the need for novel therapeutic approaches. Cancer stem cells (CSCs), a subset of tumor cells that possess self-renewal and multilineage differentiation potential, are known to be intrinsically resistant to anticancer treatments. In this review, we analyzed the implications for CSCs in drug resistance and described that multiple alterations in morphogenetic pathways (i.e., Hippo, Wnt, JAK/STAT, TGF-β, Notch, Hedgehog pathways) were suggested to be critical for CSC plasticity. By interrogating The Cancer Genome Atlas (TCGA) datasets, we first analyzed the prevalence of morphogenetic pathways alterations in solid tumors with associated outcomes. Then, by highlighting epigenetic relevance in CSC development and maintenance, we selected histone deacetylase inhibitors (HDACi) as potential agents of interest to target this subpopulation based on the pleiotropic effects exerted specifically on altered morphogenetic pathways. In detail, we highlighted the role of HDACi in solid cancers and, specifically, in the CSC subpopulation and we pointed out some mechanisms by which HDACi are able to overcome drug resistance and to modulate stemness. Although, further clinical and preclinical investigations should be conducted to disclose the unclear mechanisms by which HDACi modulate several signaling pathways in different tumors. To date, several lines of evidence support the testing of novel combinatorial therapeutic strategies based on the combination of drugs commonly used in clinical practice and HDACi to improve therapeutic efficacy in solid cancer patients.

The postoperative peak number of leukocytes after hepatectomy is a significant prognostic factor for cholangiocarcinoma

Cholangiocarcinoma (CCA) is a lethal disease. A new predictive factor to identify patients suitable for adjuvant chemotherapy is needed. The relationship between the long-term prognosis and the perioperative immune responses in patients with CCA remains unclear. We therefore investigated the clinical impact of perioperative immune responses on the long-term prognosis in patients receiving hepatectomy for CCA. We investigated 81 patients who underwent hepatectomy between February 2000 and October 2012: 57 intra-hepatic CCA (iCCA) patients and 24 extra-hepatic CCA (eCCA) patients. We checked the postoperative level of C-reactive protein and the numbers of leukocytes. A multivariate analysis of the clinicopathological factors identified 2 significant risk factors for the overall survival: The postoperative maximum number of leukocytes (PNL) among patient factors (P=0.0406) and the TNM-stage among tumor factors (P=0.0059). On evaluating the distribution of each kind of leukocyte with a multivariate analysis, both the postoperative maximum number of neutrophils (PNN) and the postoperative maximum number of eosinophils (PNE) were detected as significant factors among leukocytes (PNN/PNE, P=0.0367/0.0083). In conclusion, the PNL after hepatectomy was significantly associated with the long-term prognosis in patients with CCA. Changes in the numbers of leukocytes after hepatectomy may be a marker on treatment for CCA.

Synergistic antitumour activity of HDAC inhibitor SAHA and EGFR inhibitor gefitinib in head and neck cancer: a key role for ΔNp63α

BACKGROUND

Epidermal growth factor receptor (EGFR) overexpression is associated with the development of head and neck cancer (HNC) and represents one of the main therapeutic targets for this disease. The use of EGFR inhibitors has limited efficacy due to their primary and acquired resistance, partially because of increased epithelial to mesenchymal transition (EMT). The HDAC inhibitor SAHA has been shown to revert EMT in different tumours, including HNC. In this study, we investigated the cooperative role of SAHA and the EGFR tyrosine kinase inhibitor gefitinib in both HPV-positive and HPV-negative HNC cell lines.

METHODS

A panel of 12 HPV-positive and HPV-negative HNC cell lines were screened for cell viability upon treatment with SAHA, gefitinib and the combination of the two. Epithelial/mesenchymal marker expression, as well as activation of signalling pathway, were assessed upon SAHA treatment. ΔNp63α silencing with shRNA lentiviral particles was used to determine its role in cell proliferation, migration and TGFβ pathway activation.

RESULTS

We found that both SAHA and gefitinib have antitumour activity in both HPV-positive and HPV-negative HNC cell lines and that their combination has a synergistic effect in inhibiting cell growth. SAHA treatment reverts EMT and inhibits the expression of the transcription factor ΔNp63α. Suppression of ΔNp63α reduces EGFR protein levels and decreases cell proliferation and TGFβ-dependent migration in both HPV-positive and HPV-negative HNC cell lines.

CONCLUSIONS

Our results, by giving a clear molecular mechanism at the basis of the antitumour activity of SAHA in HNC cell lines, provide a rationale for the clinical evaluation of SAHA in combination with gefitinib in both HPV-positive and HPV-negative HNC patients. Further knowledge is key to devising additional lines of combinatorial treatment strategies for this disease.

Histone Deacetylase Inhibitors and Phenotypical Transformation of Cancer Cells

Histone deacetylase inhibitors (HDIs) are a group of potent epigenetic drugs which have been investigated for their therapeutic potential in various clinical disorders, including hematological malignancies and solid tumors. Currently, several HDIs are already in clinical use and many more are on clinical trials. HDIs have shown efficacy to inhibit initiation and progression of cancer cells. Nevertheless, both pro-invasive and anti-invasive activities of HDIs have been reported, questioning their impact in carcinogenesis. The aim of this review is to compile and discuss the most recent findings on the effect of HDIs on the epithelial-mesenchymal transition (EMT) process in human cancers. We have summarized the impact of HDIs on epithelial (E-cadherin, β-catenin) and mesenchymal (N-cadherin, vimentin) markers, EMT activators (TWIST, SNAIL, SLUG, SMAD, ZEB), as well as morphology, migration and invasion potential of cancer cells. We further discuss the use of HDIs as monotherapy or in combination with existing or novel anti-neoplastic drugs in relation to changes in EMT.

Epithelial-Mesenchymal Transition and Metastasis under the Control of Transforming Growth Factor β

Metastasis of tumor cells from primary sites of malignancy to neighboring stromal tissue or distant localities entails in several instances, but not in every case, the epithelial-mesenchymal transition (EMT). EMT weakens the strong adhesion forces between differentiated epithelial cells so that carcinoma cells can achieve solitary or collective motility, which makes the EMT an intuitive mechanism for the initiation of tumor metastasis. EMT initiates after primary oncogenic events lead to secondary secretion of cytokines. The interaction between tumor-secreted cytokines and oncogenic stimuli facilitates EMT progression. A classic case of this mechanism is the cooperation between oncogenic Ras and the transforming growth factor β (TGFβ). The power of TGFβ to mediate EMT during metastasis depends on versatile signaling crosstalk and on the regulation of successive waves of expression of many other cytokines and the progressive remodeling of the extracellular matrix that facilitates motility through basement membranes. Since metastasis involves many organs in the body, whereas EMT affects carcinoma cell differentiation locally, it has frequently been debated whether EMT truly contributes to metastasis. Despite controversies, studies of circulating tumor cells, studies of acquired chemoresistance by metastatic cells, and several (but not all) metastatic animal models, support a link between EMT and metastasis, with TGFβ, often being a common denominator in this link. This article aims at discussing mechanistic cases where TGFβ signaling and EMT facilitate tumor cell dissemination.

Hypoxia-Induced PLOD2 is a Key Regulator in Epithelial-Mesenchymal Transition and Chemoresistance in Biliary Tract Cancer

BACKGROUND

The prognosis of biliary tract cancer (BTC) is unfavorable due to its chemoresistance. Hypoxia triggers epithelial-to-mesenchymal transition (EMT), which is closely related to drug resistance. In this study, we focused on the functional roles of procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2), a hypoxia-induced gene, in BTC, and assessed the clinical significance of PLOD2.

METHODS

The expression of PLOD2 under hypoxia was assessed in BTC cell lines. Gemcitabine-resistant (GR) BTC cell lines were transfected with small interfering RNA (siRNA) against PLOD2, and EMT markers and chemoresistance were evaluated. PLOD2 expression was also characterized using immunohistochemistry in BTC clinical specimens following resection. Patient survival was analyzed and the role of PLOD2 expression was examined.

RESULTS

The expression of PLOD2 was induced by hypoxia in vitro and was upregulated in BTC-GR cell lines, which had low expression of epithelial markers and high expression of mesenchymal markers. Downregulation of PLOD2 by siRNA resulted in improved chemoresistance, recovery of epithelial markers, and reduction of mesenchymal markers. In the resected BTC samples, PLOD2 expression was significantly correlated with lymph node metastasis (p = 0.037) and stage (p = 0.001). Recurrence-free survival (p = 0.011) and overall survival (p < 0.001) rates were significantly lower in patients with high expression of PLOD2. PLOD2 expression was an independent prognostic factor for overall survival (p = 0.019).

CONCLUSIONS

The expression of PLOD2 influenced chemoresistance through EMT, and high expression of PLOD2 was a significant unfavorable prognostic factor in BTC patients. PLOD2 might be a potential therapeutic target for overcoming chemoresistance.

Role of histone deacetylase 1 in distant metastasis of pancreatic ductal cancer

Current therapies for pancreatic ductal cancer (PDAC) do not sufficiently control distant metastasis. Thus, new therapeutic targets are urgently needed. Numerous studies have suggested that the epithelial-mesenchymal transition (EMT) is pivotal for metastasis of carcinomas. The fact that the EMT is reversible suggests the possibility that it is induced by an epigenetic mechanism. In this study, we aimed to investigate the role of histone deacetylase 1 (HDAC1), which is an epigenetic mechanism on distant metastasis of PDAC. We investigated the HDAC1 expression in 103 resected PDAC specimens obtained from patients who were treated with/without preoperative therapy using immunohistochemistry. To validate the findings in the clinical samples, we evaluated the HDAC1 activity, the EMT-associated genes and the migration/invasion ability in vitro, and performed an HDAC1 inhibitor assay. The high expression of HDAC1 in clinical samples was significantly associated with poor progression-free survival, especially distant metastasis-free survival. In vitro, HDAC1 inhibitors decreased the invasion ability and reversed the EMT change; the only factor to show a concomitant decrease was the expression of SNAIL. We confirmed that the HDAC1 expression was associated with the SNAIL expression in clinical samples. Moreover, the resistant cells and parental cells did not show any significant differences in the expression of HDAC1; this was consistent with the finding that preoperative therapy did not alter the HDAC1 expression in clinical samples. The targeting of HDAC1, which could suppress metastasis by inhibiting the EMT, is a promising treatment option for PDAC.

The Kraken Wakes: induced EMT as a driver of tumour aggression and poor outcome

Epithelial mesenchymal transition (EMT) describes the shift of cells from an epithelial form to a contact independent, migratory, mesenchymal form. In cancer the change is linked to invasion and metastasis. Tumour conditions, including hypoxia, acidosis and a range of treatments can trigger EMT, which is implicated in the subsequent development of resistance to those same treatments. Consequently, the degree to which EMT occurs may underpin the entire course of tumour progression and treatment response in a patient. In this review we look past the protective effect of EMT against the initial treatment, to the role of the mesenchymal state, once triggered, in promoting disease growth, spread and future treatment insensitivity. In patients a correlation was found between the propensity of a treatment to induce EMT and failure of that treatment to provide a survival benefit, implicating EMT induction in accelerated tumour progression after treatment cessation. Looking to the mechanisms driving this detrimental effect; increased proliferation, suppressed apoptosis, stem cell induction, augmented angiogenesis, enhanced metastatic dissemination, and immune tolerance, can all result from treatment-induced EMT and could worsen outcome. Evidence also suggests EMT induction with earlier therapies attenuates benefits of later treatments. Looking beyond epithelial tumours, de-differentiation also has therapy-attenuating effects and reversal thereof may yield similar rewards. A range of potential therapies are in development that may address the diverse mechanisms and molecular control systems involved in EMT-induced accelerated progression. Considering the broad reaching effects of mesenchymal shift identified, successful deployment of such treatments could substantially improve patient outcomes.

Hyper-acetylation contributes to the sensitivity of chemo-resistant prostate cancer cells to histone deacetylase inhibitor Trichostatin A

Therapeutic agents are urgently needed for treating metastatic castration‐refractory prostate cancer (mCRPC) that is unresponsive to androgen deprivation and chemotherapy. Our screening assays demonstrated that chemotherapy‐resistant prostate cancer (PCa) cells are more sensitive to HDAC inhibitors than paired sensitive PCa cells, as demonstrated by cell proliferation and apoptosis in vitro and in vivo. Kinetic study revealed that TSA‐induced apoptosis was significantly dependent on enhanced transcription and protein synthesis in an early stage, which subsequently caused ER stress and apoptosis. ChIP analysis indicated that TSA increased H4K16 acetylation, promoting ER stress gene transcription. The changes in Ac‐H4K16, ATF3 and ATF4 were also validated in TSA‐treated animals. Further study revealed the higher enzyme activity of HDACs and an increase in acetylated proteins in resistant cells. The higher nucleocytoplasmic acetyl‐CoA in resistant cells was responsible for elevated acetylation status of protein and a more vigorous growth state. These results strongly support the pre‐clinical application of HDAC inhibitors for treating chemotherapy‐resistant mCRPC.

Bcl-2 Antiapoptotic Family Proteins and Chemoresistance in Cancer

Cancer is a daunting global problem confronting the world's population. The most frequent therapeutic approaches include surgery, chemotherapy, radiotherapy, and more recently immunotherapy. In the case of chemotherapy, patients ultimately develop resistance to both single and multiple chemotherapeutic agents, which can culminate in metastatic disease which is a major cause of patient death from solid tumors. Chemoresistance, a primary cause of treatment failure, is attributed to multiple factors including decreased drug accumulation, reduced drug-target interactions, increased populations of cancer stem cells, enhanced autophagy activity, and reduced apoptosis in cancer cells. Reprogramming tumor cells to undergo drug-induced apoptosis provides a promising and powerful strategy for treating resistant and recurrent neoplastic diseases. This can be achieved by downregulating dysregulated antiapoptotic factors or activation of proapoptotic factors in tumor cells. A major target of dysregulation in cancer cells that can occur during chemoresistance involves altered expression of Bcl-2 family members. Bcl-2 antiapoptotic molecules (Bcl-2, Bcl-xL, and Mcl-1) are frequently upregulated in acquired chemoresistant cancer cells, which block drug-induced apoptosis. We presently overview the potential role of Bcl-2 antiapoptotic proteins in the development of cancer chemoresistance and overview the clinical approaches that use Bcl-2 inhibitors to restore cell death in chemoresistant and recurrent tumors.

Mocetinostat combined with gemcitabine for the treatment of leiomyosarcoma: Preclinical correlates

Leiomyosarcoma (LMS) is a malignant soft tissue sarcoma (STS) with a dismal prognosis following metastatic disease. Chemotherapeutic intervention has demonstrated to have modest clinical efficacy with no curative potential in LMS patients. Previously, we demonstrated pan-HDAC inhibition to have a superior effect in various complex karyotypic sarcomas. In this study, our goal is to evaluate the therapeutic efficacy of mocetinostat alone and in combination with gemcitabine in LMS. Human leiomyosarcoma (LMS) cell lines were used for in vitro and in vivo studies. Compounds tested included the class I HDAC inhibitor, mocetinostat, and nucleoside analog, gemcitabine. MTS and clonogenic assays were used to evaluate the effect of mocetinostat on LMS cell growth. Cleaved caspase 3/7 analysis was used to determine the effects of mocetinostat on apoptosis. Compusyn software was used to determine in vitro synergy studies for the combination of mocetinostat plus gemcitabine. A LMS xenograft model in SCID mice was used to test the impact of mocetinostat alone, gemcitabine alone and the combination of mocetinostat plus gemcitabine. Mocetinostat abrogated LMS cell growth and clonogenic potential, and enhanced apoptosis in LMS cell lines. The combination of mocetinostat plus gemcitabine exhibited a synergistic effect in LMS cells in vitro. Similarly, mocetinostat combined with gemcitabine resulted in superior anti-LMS effects in vivo. Mocetinostat reduced the expression of gemcitabine-resistance markers RRM1, RRM2, and increased the expression of gemcitabine-sensitivity marker, hENT1, in LMS cells. LMS are aggressive, metastatic tumors with poor prognosis where effective therapeutic interventions are wanting. Our studies demonstrate the potential utility of mocetinostat combined with gemcitabine for the treatment of LMS.

Fatty Acid-Mediated Stromal Reprogramming of Pancreatic Stellate Cells Induces Inflammation and Fibrosis That Fuels Pancreatic Cancer

OBJECTIVES

Pancreatic ductal adenocarcinoma is one of the deadliest diseases worldwide. Fatty acids (FAs) have properties that affect both cancer cells and tumor environment. We assessed the effects of FAs on malignant characteristics in a pancreatic cancer and pancreatic stellate cell (PSC) coculture model. This study aimed to clarify the FA signature of PSC-derived inflammation and fibrosis in vitro and in a clinicopathological analysis.

METHODS

The in vitro model involved coculture of the human pancreatic cancer cell lines PANC-1 and MIA PaCa-2 with human PSCs. Clinical histological samples were analyzed to characterize the surgical margins of samples from patients who received distal pancreatectomies.

RESULTS

The pancreatic cancer cells took up lipids from the culture media. Saturated and unsaturated FAs were required to induce inflammatory responses in human PSCs, and the cocultures showed fibrotic changes. Clinical samples from pancreatic ductal adenocarcinoma patients had more fatty and fibrotic changes in the normal tissue in the surgical margins than samples from noncancer patients.

CONCLUSIONS

Inflammation and fibrosis levels were increased in pancreatic cancer specimens, supporting the in vitro observations and suggesting that PSCs contribute to pancreatic carcinogenesis. Pancreatic stellate cells thus represent a potential therapeutic target for suppressing stromal changes in pancreatic cancer.

Emerging Therapeutics to Overcome Chemoresistance in Epithelial Ovarian Cancer: A Mini-Review

Ovarian cancer is the fifth leading cause of cancer death among women and the most lethal gynecologic malignancy. One of the leading causes of death in high-grade serous ovarian cancer (HGSOC) is chemoresistant disease, which may present as intrinsic or acquired resistance to therapies. Here we discuss some of the known molecular mechanisms of chemoresistance that have been exhaustively investigated in chemoresistant ovarian cancer, including drug efflux pump multidrug resistance protein 1 (MDR1), the epithelial–mesenchymal transition, DNA damage and repair capacity. We also discuss novel therapeutics that may address some of the challenges in bringing approaches that target chemoresistant processes from bench to bedside. Some of these new therapies include novel drug delivery systems, targets that may halt adaptive changes in the tumor, exploitation of tumor mutations that leave cancer cells vulnerable to irreversible damage, and novel drugs that target ribosomal biogenesis, a process that may be uniquely different in cancer versus non-cancerous cells. Each of these approaches, or a combination of them, may provide a greater number of positive outcomes for a broader population of HGSOC patients.

Targeting epithelial-mesenchymal plasticity in cancer: clinical and preclinical advances in therapy and monitoring

The concept of epithelial-mesenchymal plasticity (EMP), which describes the dynamic flux within the spectrum of phenotypic states that invasive carcinoma cells may reside, is being increasingly recognised for its role in cancer progression and therapy resistance. The myriad of events that are able to induce EMP, as well as the more recently characterised control loops, results in dynamic transitions of cancerous epithelial cells to more mesenchymal-like phenotypes through an epithelial-mesenchymal transition (EMT), as well as the reverse transition from mesenchymal phenotypes to an epithelial one. The significance of EMP, in its ability to drive local invasion, generate cancer stem cells and facilitate metastasis by the dissemination of circulating tumour cells (CTCs), highlights its importance as a targetable programme to combat cancer morbidity and mortality. The focus of this review is to consolidate the existing knowledge on the strategies currently in development to combat cancer progression via inhibition of specific facets of EMP. The prevalence of relapse due to therapy resistance and metastatic propensity that EMP endows should be considered when designing therapy regimes, and such therapies should synergise with existing chemotherapeutics to benefit efficacy. To further improve upon EMP-targeted therapies, it is imperative to devise monitoring strategies to assess the impact of such treatments on EMP-related phenomenon such as CTC burden, chemosensitivity/-resistance and micrometastasis in patients.

Epithelial-to-Mesenchymal Transition: Epigenetic Reprogramming Driving Cellular Plasticity

Epithelial-to-mesenchymal transition (EMT) is a process in which epithelial cells lose their junctions and polarity to gain a motile mesenchymal phenotype. EMT is essential during embryogenesis and adult physiological processes like wound healing, but is aberrantly activated in pathological conditions like fibrosis and cancer. A series of transcription factors (EMT-inducing transcription factor; EMT-TF) regulate the induction of EMT by repressing the transcription of epithelial genes while activating mesenchymal genes through mechanisms still debated. The nuclear interaction of EMT-TFs with larger protein complexes involved in epigenetic genome modulation has attracted recent attention to explain functions of EMT-TFs during reprogramming and cellular differentiation. In this review, we discuss recent advances in understanding the interplay between epigenetic regulators and EMT transcription factors and how these findings could be used to establish new therapeutic approaches to tackle EMT-related diseases.

Expression of carbonic anhydrase IX is associated with poor prognosis through regulation of the epithelial‑mesenchymal transition in hepatocellular carcinoma

Carbonic anhydrase 9 (CA9) is a plasma membrane-associated isoenzyme that catalyzes pH regulation under hypoxic conditions. CA9 is transcriptionally regulated by hypoxia-inducible factor 1. Recent studies reported that hypoxia also promoted the epithelial-mesenchymal transition (EMT) in various cancers. In the present study, we evaluated the relationship between CA9 expression and EMT in vitro with two hepatoma cell lines. We also examined the clinical significance of CA9 expression in 117 consecutive patients that underwent hepatectomies for hepatocellular carcinoma (HCC). We evaluated CA9 expression and EMT induction under hypoxia with quantitative RT-PCR, western blot analysis and immunofluorescence staining, in HuH7 and HepG2 cells. We knocked down CA9 expression with small interfering RNA to evaluate the relationship between CA9 and EMT. We found that hypoxia induced CA9 expression in HCC cells and promoted EMT, evidenced by a loss of E-cadherin and an increase in N-cadherin. Twist, a transcriptional regulator of EMT, was also upregulated with hypoxia. The CA9 deficiency attenuated hypoxia-induced changes in E-cadherin and N-cadherin. Immunohistochemical evaluations of patient samples showed that CA9 was expressed in 50.4% of patients (59/117). However, patients with and without CA9 expression were not significantly different in clinicopathological factors. Nevertheless, a multivariate analysis showed that CA9 expression was an independent factor for both recurrence and prognosis among patients that underwent curative surgery for HCC. In conclusion, this study revealed that CA9 expression was a pivotal predictive factor for poor prognosis after radical surgery for HCC. Moreover, the CA9 regulation of the expression of EMT-related molecules represented a mechanism that enhanced malignant potential.

The EMT spectrum and therapeutic opportunities

Carcinomas are phenotypically arrayed along an epithelial–mesenchymal transition (EMT) spectrum, a developmental program currently exploited to understand the acquisition of drug resistance through a re‐routing of growth factor signaling. This review collates the current approaches employed in developing therapeutics against cancer‐associated EMT, and provides an assessment of their respective strengths and drawbacks. We reflect on the close relationship between EMT and chemoresistance against current targeted therapeutics, with a special focus on the epigenetic mechanisms that link these processes. This prompts the hypothesis that carcinoma‐associated EMT shares a common epigenetic pathway to cellular plasticity as somatic cell reprogramming during tissue repair and regeneration. Indeed, their striking resemblance suggests that EMT in carcinoma is a pathological adaptation of an intrinsic program of cellular plasticity that is crucial to tissue homeostasis. We thus propose a revised approach that targets the epigenetic mechanisms underlying pathogenic EMT to arrest cellular plasticity regardless of upstream cancer‐driving mutations.

ZEB1 Mediates Drug Resistance and EMT in p300-Deficient CRC

We discuss the hypothesis that ZEB1-Wnt-p300 signaling integrates epithelial to mesenchymal transition (EMT) and resistance to histone deacetylase inhibitors (HDACis) in colorectal cancer (CRC) cells. The HDACi butyrate, derived from dietary fiber, has been linked to CRC prevention, and other HDACis have been proposed as therapeutic agents against CRC. We have previously discussed that resistance to butyrate likely contributes to colonic carcinogenesis, and we have demonstrated that butyrate resistance leads to cross-resistance to cancer therapeutic HDACis. Deregulated Wnt signaling is the major initiating event in most CRC cases. One mechanism whereby butyrate and other HDACis exert their anti-CRC effects is via Wnt signaling hyperactivation, which promotes CRC cell apoptosis. The histone acetylases (HATs) CBP and p300 are mediators of Wnt transcriptional activity, and play divergent roles in the downstream consequences of Wnt signaling. CBP-mediated Wnt signaling is associated with cell proliferation and stem cell maintenance; whereas, p300-mediated Wnt activity is associated with differentiation. We have found that CBP and p300 differentially affect the ability of butyrate to influence Wnt signaling, apoptosis, and proliferation. ZEB1 is a Wnt signaling-targeted gene, whose product is a transcription factor expressed at the invasive front of carcinomas where it promotes malignant progression and EMT. ZEB1 is typically a transcriptional repressor; however, when associated with p300, ZEB1 enhances transcription. These changes in ZEB1 activity likely affect the cancer cell phenotype. ZEB1 has been shown to promote resistance to chemotherapeutic agents, and expression of ZEB1 is upregulated in butyrate-resistant CRC cells that lack p300 expression. Since the expression of ZEB1 correlates with poor outcomes in cancer, ZEB represents a relevant therapeutic target. Here we propose that targeting the signaling network established by ZEB1, Wnt signaling, and p300 signaling can reverse HDACi resistance and inhibit EMT.

HTP Nutraceutical Screening for Histone Deacetylase Inhibitors and Effects of HDACis on Tumor-suppressing miRNAs by Trichostatin A and Grapeseed (Vitis vinifera) in HeLa cells

BACKGROUND/AIM

Aggressive tumor malignancies are a consequence of delayed diagnosis, epigenetic/phenotype changes and chemo-radiation resistance. Histone deacetylases (HDACs) are a major epigenetic regulator of transcriptional repression, which are highly overexpressed in advanced malignancy. While original chemotherapy drugs were modeled after phytochemicals elucidated by botanical screenings, HDAC inhibitors (HDACi) such as apicidin, trichostatin A (TSA) and butyrate were discovered as products of fungus and microbes, in particular, gut microbiota. Therefore, a persistent question remains as to the inherent existence of HDACis in raw undigested dietary plant material. In this study, we conduct a high-throughput (HTP) screening of ~1,600 non-fermented commonly used nutraceuticals (spices, herbs, teas, vegetables, fruits, seeds, rinds etc.) at (<600 μg/ml) and food-based polyphenolics (<240 μg/ml) for evidence of HDAC activity inhibition in nuclear HeLa cell lysates.

MATERIALS AND METHODS

Human HDAC kinetic validation was performed using a standard fluorometric activity assay, followed by an enzymatic-linked immuno-captured ELISA. Both methods were verified using HDACi panel drugs: TSA, apicidin, suberohydroxamic acid, M344, CL-994, valproic acid and sodium phenylbutyrate. The HTP screening was then conducted, followed by a study comparing biological effects of HDACis in HeLa cells, including analysis of whole-transcriptome non-coding RNAs using Affymetrix miRNA 4.1-panel arrays.

RESULTS

The HTP screening results confirmed 44/1600 as potential HDACis to which 31 were further eliminated as false-positives. Methodological challenges/concerns are addressed regarding plant product false-positives that arise from the signal reduction of commercial lysine development reagents. Only 13 HDACis were found having an IC₅₀ under <200 μg/ml: Grapeseed extract (Vitis vinifera), Great burnet root (Sanguisorba Officinalis), Babul (Acacia arabica), Chinese gallnut (Melaphis chinensis), Konaberry extract (Coffea arabica), Uva Ursi (Arctostaphylos uva ursi), Green tea (Camellia sinensis), Meadowsweet (Filipendula ulmaria), Sassafras (Sassafras officinale), Turkey rhubarb (Rheum palmatum), epigallocatechin gallate (EGCG), gossypol and gallic acid. Next, we investigate the biological consequence of HDACi panel drugs in HeLa cells, where the data suggest predominant effects are anti-mitotic rather than cytotoxic. Lastly, differential effects of TSA vs. GSE at sub-lethal concentrations tested on HeLa cells show 6,631 miRNAs expressed in resting cells, 35 significantly up-regulated (TSA) and 81 up-regulated (GSE), with several miRNAs overlapping in the upward direction by both GSE and TSA (e.g. hsa-miR-23b-5p, hsa-miR-27b-5p, hsa-miR-1180-3p, hsa-miR-6880-5p and hsa-mir-943). Using DIANA miRNA online tools, it was determined that GSE and TSA simultaneously cause overexpression of similar miRNAs predicted to destroy the following influential oncogenes: NFkB, NRAS, KRAS, HRAS, MYC, TGFBR1, E2F1, E2F2, BCL21, CDKN1A, CDK6, HIF1a, and VEGFA.

CONCLUSION

The data from this study show that plant- based HDACis are relatively rare, and can elicit a similar pattern to TSA in up-regulating miRNAs involved with tumor suppression of HeLa cervical carcinoma.

Roles and epigenetic regulation of epithelial-mesenchymal transition and its transcription factors in cancer initiation and progression

The epithelial-mesenchymal transition (EMT) is a crucial developmental process by which epithelial cells undergo a mesenchymal phenotypic change. During EMT, epigenetic mechanisms including DNA methylation and histone modifications are involved in the regulation of EMT-related genes. The epigenetic gene silencing of the epithelial marker E-cadherin has been well characterized. In particular, three major transcriptional repressors of E-cadherin, Snail, ZEB, and Twist families, also known as EMT-inducing transcription factors (EMT-TFs), play a crucial role in this process by cooperating with multiple epigenetic modifiers. Furthermore, recent studies have identified the novel epigenetic modifiers that control the expression of EMT-TFs, and these modifiers have emerged as critical regulators of cancer development and as novel therapeutic targets for human cancer. In this review, the diverse functions of EMT-TFs in cancer progression, the cooperative mechanisms of EMT-TFs with epigenetic modifiers, and epigenetic regulatory roles for the expression of EMT-TFs will be discussed.

Valproic acid inhibits irradiation-induced epithelial-mesenchymal transition and stem cell-like characteristics in esophageal squamous cell carcinoma

Esophageal carcinoma is one of the most aggressive malignancies, and is characterized by poor response to current therapy and a dismal survival rate. In this study we investigated whether irradiation induces epithelial-mesenchymal transition (EMT) in esophageal squamous cell carcinoma (ESCC) TE9 cells and whether the classic histone deacetylase (HDAC) inhibitor valproic acid (VPA) suppresses these changes. First, we showed that 2 Gy irradiation induced spindle cell-like morphologic changes, decreased expression of membranous E-cadherin, upregulated vimentin expression, and altered the localization of β-catenin from its usual membrane-bound location to cytoplasm in TE9 cells. Irradiation induced upregulation of transcription factors including Slug, Snail, and Twist, which regulate EMT. Stimulation by irradiation resulted in increased TGF-β1 and HIF-1α expression and induced Smad2 and Smad3 phosphorylation. Furthermore, irradiation enhanced CD44 expression, indicating acquisition of cancer stem-like cell properties. In addition, irradiation enhanced invasion and migration ability with upregulation of matrix metalloproteinases. These findings indicate that single-dose irradiation can induce EMT in ESCC cells. Second, we found that treatment with 1 mM VPA induced reversal of EMT caused by irradiation in TE9 cells, resulting in attenuated cell invasion and migration abilities. These results suggest that VPA might have clinical value to suppress irradiation-induced EMT. The reversal of EMT by HDAC inhibitors may be a new therapeutic strategy to improve the effectiveness of radiotherapy in ESCC by inhibiting the enhancement of invasion and metastasis.

Mechanisms of TGFβ-Induced Epithelial-Mesenchymal Transition

Transitory phenotypic changes such as the epithelial–mesenchymal transition (EMT) help embryonic cells to generate migratory descendants that populate new sites and establish the distinct tissues in the developing embryo. The mesenchymal descendants of diverse epithelia also participate in the wound healing response of adult tissues, and facilitate the progression of cancer. EMT can be induced by several extracellular cues in the microenvironment of a given epithelial tissue. One such cue, transforming growth factor β (TGFβ), prominently induces EMT via a group of specific transcription factors. The potency of TGFβ is partly based on its ability to perform two parallel molecular functions, i.e. to induce the expression of growth factors, cytokines and chemokines, which sequentially and in a complementary manner help to establish and maintain the EMT, and to mediate signaling crosstalk with other developmental signaling pathways, thus promoting changes in cell differentiation. The molecules that are activated by TGFβ signaling or act as cooperating partners of this pathway are impossible to exhaust within a single coherent and contemporary report. Here, we present selected examples to illustrate the key principles of the circuits that control EMT under the influence of TGFβ.