Novel Adiponectin Receptor Agonist Inhibits Cholangiocarcinoma via Adenosine Monophosphate-activated Protein Kinase

BACKGROUND

Cholangiocarcinoma (CCA) has a poor prognosis and only limited palliative treatment options. The deficiency of adiponectin and adenosine monophosphate-activated protein kinase (AMPK) signaling was reported in several malignancies, but the alteration of these proteins in CCA is still unclear.

OBJECTIVES

This study aimed to assess the role of adiponectin and AMPK signaling in CCA. Furthermore, AdipoRon, a novel adiponectin receptor (AdipoR) agonist, was evaluated in vitro and in vivo as a new anti-tumor therapy for CCA.

METHODS

The expression of AdipoR1 and p-AMPKα in human tissue microarrays (TMAs) was evaluated by immunohistochemistry staining (IHC). The effect of 2-(4-Benzoylphenoxy)-N-[1-(phenylmethyl)- 4-piperidinyl]-acetamide (AdipoRon) was investigated in vitro with proliferation, crystal violet, migration, invasion, colony formation, senescence, cell cycle and apoptosis assays and in vivo using a CCA engineered mouse model (AlbCre/LSL-KRASG12D/p53L/L). RT-qPCR and western blot methods were applied to study molecular alterations in murine tissues.

RESULTS

AdipoR1 and p-AMPKα were impaired in human CCA tissues, compared to adjacent non-tumor tissue. There was a positive correlation between the AdipoR1 and p-AMPKα levels in CCA tissues. Treatment with AdipoRon inhibited proliferation, migration, invasion and colony formation and induced apoptosis in a time- and dose-dependent manner in vitro(p<0.05). In addition, AdipoRon reduced the number of CCA and tumor volume, prolonged survival, and decreased metastasis and ascites in the treated group compared to the control group (p<0.05).

CONCLUSIONS

AdipoR1 and p-AMPKα are impaired in CCA tissues, and AdipoRon effectively inhibits CCA in vitro and in vivo. Thus, AdipoRon may be considered as a potential anti-tumor therapy in CCA.

Adiponectin Receptor Agonist Effectively Suppresses Hepatocellular Carcinoma Growth

Hepatocellular carcinoma (HCC) is the second lethal cancer. Short overall survival, low five-year survival rate, and unimproved treatment efficacy urge the need to improve HCC prognosis. Adiponectin is key protector against cancer and hepatic abnormalities. Hypoadiponectinemia occurs in and promotes carcinogenesis and hepatic diseases. Adiponectin reactivation by different methods showed impressive effect against cancer and hepatic diseases. Recently, AdipoRon, an adiponectin receptor agonist, can interact with both Adiponectin receptors. AdipoRon showed promising anti-cancer effect in some cancers, but no study on HCC yet. The in vitro effect of AdipoRon on HCC was investigated by cell viability, migration, invasion, colony formation and apoptosis assays. The signalling alteration was determined by RT-qPCR and Western blot. The effect of treatment was interpreted by comparison between treatments and control. The difference between two cell lines was relatively compared. Our results showed significant in vitro anti-cancer effect of AdipoRon via AMPK- and dose-dependent manner. Huh7 cells showed a lower level of AdipoR1/2 and a superior proliferation and aggressiveness, compared to Hep3B. In addition, Huh7 cells were more sensitive to AdipoRon treatment (lower IC50, less cell growth, migration, invasion and colonies upon AdipoRon treatment) than Hep3B cells. In conclusion, AdipoRon effectively inhibited HCC growth and invasiveness in vitro. The deficient expression of adiponectin receptors affects efficacy of AdipoRon and aggressiveness of HCC cells.

The safety of CAR-T cells and PD-1 antibody combination on an experimental model

Chimeric antigen receptor (CAR) T cells and PD-1 antibodies (PD-1 Ab) are emergent immunotherapies with unprecedented efficacy. The presence of PD-1 on T cells contributes to hypofunction of CAR-T therapy and inhibition of PD-1 enhances anti-cancer effect of CAR-T cells. Therefore, the combination of CAR-T cells and PD-1 antibody is a promissing strategy for cancer treatment. This study aims to establish our in-house CAR-T cells and evaluate the safety of CAR-T cells in combination with PD-1 antibody in animals. The toxicity of CD19-CAR-T cells was examined using Swiss Webster mice. Four mouse groups were treated with control, CAR-T, PD-1 antibody or CAR-T + PD-1 antibody. Mice's overall status was monitored and recorded. At the end-point, hematological and biochemical indices were quantified, histopathology of liver and kidney was evaluated by pathologists. The relative abnormal ratio and absolute values were compared between groups. We generated our in-house CAR-T cells and used them for safety evaluation in mice. The increase in mouse weight was observed in all groups after treatment and the weight was comparable between groups. The hematological, biochemical and histopathological parameters were equivalent between groups, except for liver grain degeneration occurred in treatment groups. Thus, CAR-T cells, PD-1 Ab and their combination were safe in mice. We successfully produced our in-house CAR-T cells and the combination of our CAR-T cells and PD-1 antibody was safe in mice with comparable values of hematopoietic indices, liver and kidney functions. Longer follow-up might be necessary to evaluate their effect on the liver.

Determination of Both TP53 Mutation Status and the Amount of p53 Protein Has Limited Diagnostic Importance for Patients with Ovarian Cancer

BACKGROUND

Ovarian cancer is one of the most aggressive types of gynecologic cancers. Many patients have a relapse within two years after diagnosis and subsequent therapy. Among different genetic changes generally believed to be important for the development of cancer, TP53 is the most common mutation in the case of ovarian tumors.

OBJECTIVE

Our work aims to compare the outcomes of different comparisons based on the overall survival of ovarian cancer patients, determination of TP53 status, and amount of p53 protein in tumor tissues.

METHODS

We analyzed and compared a collective of 436 ovarian patient's data. Extracted data include TP53 mutation status, p53 protein level, and information on the overall survival. Values for p53 protein level in dependence of TP53 mutation status were compared using the Independent-Samples t-Test. Survival analyses were displayed by Kaplan-Meier plots, using the log-rank test to check for statistical significance.

RESULTS

We have not found any statistically significant correlations between determination of TP53 status, amount of p53 protein in tumor tissues, and overall survival of ovarian cancer patients.

CONCLUSION

In ovarian tumors both determination of TP53 status as well as p53 protein amount has only limited diagnostic importance.

EXTH-48. NOVEL COMBINATION THERAPY IN PRECLINICAL GLIOMA MODELS USING THE CELL CYCLE STABILIZING COMPOUND ARGYRIN F AND CHECKPOINT INHIBITION

Glioblastoma are incurable aggressive tumors and remain a therapeutic challenge. Glioblastoma frequently harbor alterations in the retinoblastoma pathway with subsequent cell cycle abnormalities. Here, we aimed to investigate the anti-glioma activity of the cell cycle-stabilizing compound Argyrin F and its potential treatment-induced vulnerabilities to exploit possibilities for novel combination therapies. We investigated cell viability, clonogenic survival, cell cycle status and immunoblots of human and murine glioma cells treated with Argyrin F. Moreover, we established an ex vivo glioma model using residual freshly resected tissue from patients, i.e. patient-derived microtumors (PDMs). Additionally, we extracted autologous tumor infiltrating lymphocytes (TILs) to perform co-culturing experiments. We performed mass spectrometry-based immunopeptidomics and used the orthotopic syngeneic SMA560/VM/Dk glioma mouse model. Argyrin F displayed anti-glioma efficacy in glioma cell lines in vitro and in PDM models ex vivo. Moreover, Argyrin F treatment induced cell cycle arrest, reduced clonogenic survival in vitro and prolonged survival in vivo. Argyrin F-treated SMA560 glioma displayed 4.6-fold more glioma-infiltrating CD8+ T cells. We discovered a distinctive treatment-induced immunopeptidome. Combination of Argyrin F plus PD-1 antibody increased cellular toxicity in PDM/TILs co-cultures ex vivo and prolonged overall survival compared with monotherapies in vivo. We conclude that our experimental data suggest a novel combination of Argyrin F plus PD-1 blockade and its clinical translation.

Cholangiocarcinoma Therapeutics: An Update

BACKGROUND

Cholangiocarcinoma (CCA) is the second most common hepatobiliary cancer and associated with a poor prognosis. Only one-third of CCA cases are diagnosed at operable stages. However, a high rate of relapse has been observed postoperatively. Besides screening for operable individuals, efficacious therapeutic for recurrent and advanced CCA is urgently needed. The treatment outcome of available therapeutics is important to clarify clinical indication and facilitate the development of treatment strategies.

OBJECTIVE

This review aims to compare the treatment outcome of different therapeutics based on both overall survival and progression-free survival.

METHODS

Over one hundred peer-reviewed articles were examined. We compared the treatment outcome between different treatment methods, including tumor resection with or without postoperative systematic therapy, chemotherapies including FOFLOX, and targeted therapies, such as IDH1, K-RAS, and FGFR inhibitors. Notably, the scientific basis and outcome of available treatment methods were compared with the standard first-line therapy.

RESULTS

CCAs at early stages should firstly undergo tumor resection surgery, followed by postoperative treatment with Capecitabine. Chemotherapy can be considered as a preoperative option for unresectable CCAs. Inoperable CCAs with genetic aberrances like FGFR alterations, IDH1, and KRAS mutations should be considered with targeted therapies. Fluoropyrimidine prodrug (S-1)/Gemcitabine/Cisplatin and nab-Paclitaxel/Gemcitabine/Cisplatin show favorable outcome which hints at the triplet regimen to be superior to Gemcitabine/Cisplatin on CCA. The triplet chemotherapeutic should be tested further compared to Gemcitabine/Cisplatin among CCAs without genetic alterations. Gemcitabine plus S-1 was recently suggested as the convenient and equivalent standard first-line for advanced/recurrent biliary tract cancer.

CONCLUSION

This review provides a comparative outcome between novel targeted therapies and currently available therapeutics.

Cell-to-Cell Transmission of the Unfolded Protein Response - Is it a Real Phenomenon?

Cell-to-cell transmission of the unfolded protein response (UPR) is one of the most exciting observations recently made in cell biology. One of the most efficient tools to induce UPR response in cell culture is treatment with specific compounds leading to accumulation of misfolded proteins in endoplasmic reticulum. In this article we discussed opposite opinions regarding application of this approach and possible sources of experimental artefacts.

Targeting interleukin 6 signaling by monoclonal antibody siltuximab on cholangiocarcinoma

BACKGROUND AND AIM

Cholangiocarcinoma has an unimproved prognosis. Interleukin 6 (IL-6) has an oncogenic potential in some cancer diseases. However, the role of IL-6 in cholangiocarcinoma carcinogenesis is not well understood. The current study investigated the role of IL-6 signaling in cholangiocarcinoma carcinogenesis and efficacy of siltuximab treatment on cholangiocarcinoma in vitro and in vivo.

METHODS

The expression of IL-6 was analyzed on human cholangiocarcinoma cell lines and murine and human cholangiocarcinoma tissues, using reverse transcription real-time polymerase chain reaction and immunohistochemistry. In addition, the effect of anti-IL-6 chimeric monoclonal antibody, siltuximab, was investigated in vitro by proliferation, migration, and two-dimensional and three-dimensional invasion assays and in vivo by xenograft mouse model. Western blot was applied to study the molecular alteration.

RESULTS

Our result shows high expression of IL-6 in human cholangiocarcinoma cells, and IL-6 stimulants enhance cholangiocarcinoma cell proliferation. In addition, murine and human cholangiocarcinoma tissues express significantly higher levels of IL-6, compared with adjacent non-tumor tissues. On the cholangiocarcinoma engineered mouse model, IL-6 level is associated with tumor volume. Taken together, our data indicate an oncogenic potential of IL-6 in cholangiocarcinoma carcinogenesis. Siltuximab sufficiently abrogates IL-6 signaling and inhibits cholangiocarcinoma progression in vitro and in vivo. The results additionally indicate a relative alteration of IL-6 signaling and its molecular targets, such as STAT3, Wnt/β-catenin, and mesenchymal markers.

CONCLUSIONS

Interleukin 6 plays an essential role in cholangiocarcinoma carcinogenesis, and siltuximab has the potential to be considered as a new treatment option for cholangiocarcinoma patients.

Hypoxia induced Sonic Hedgehog signaling regulates cancer stemness, epithelial-to-mesenchymal transition and invasion in cholangiocarcinoma

Aberrant activation of Sonic Hedgehog (SHH) pathway has been implicated in a variety of cancers including cholangiocarcinoma (CC); however, the influencing factors are still unknown. Additionally, intratumoral hypoxia is known to contribute towards therapeutic resistance through modulatory effects on various pathways. In this study, we investigated the relationship between hypoxia and SHH pathway activation and the effect of this interplay on cancer stemness and epithelial-to- mesenchymal transition (EMT) during cholangiocarcinogenesis. Hypoxia promoted SHH pathway activation, evidenced by upregulated SHH and SMO levels, and enhanced glioma-associated oncogene homolog 1 (GLI1) nuclear translocation; whereas silencing of HIF-1α impaired SHH upregulation. Hypoxia also enhanced the expression of cancer stem cell (CSC) transcription factors (NANOG, Oct4, SOX2), CD133 and EMT markers (N-cadherin, Vimentin), thereby supporting invasion. Cyclopamine treatment suppressed hypoxia induced SHH pathway activation, consequently reducing invasiveness by downregulating the expression of CSC transcription factors, CD133 and EMT. Cyclopamine induced apoptosis in CC cells under hypoxia, suggesting that hypoxia induced activation of SHH pathway has modulatory effects on CC progression. Therefore, SHH signaling is proposed as a target for CC treatment, which is refractory to standard chemotherapy.

Silencing of Kangai 1 C-terminal interacting tetraspanin suppresses progression of cholangiocarcinoma

Cholangiocarcinoma (CC) is the second most common primary hepatic malignancy. CC treatment options are very limited especially for patients with distant metastasis. Kangai 1 C-terminal interacting tetraspanin (KITENIN) is highly expressed in numerous cancers, but the role of KITENIN in CC remains unknown. Here, we have investigated for the first time the function of KITENIN in human CC cell lines (TFK-1, SZ-1), tissues and a CC mouse model (Alb-Cre/LSL-KRAS^G12D/p53^L/L). KITENIN was expressed in 92.2% of human CC tissues, in murine CC samples and also in human CC cell lines. Knockdown of KITENIN by small interfering RNA (siRNA) effectively reduced proliferation, migration, invasion and colony formation in both intra- and extra-hepatic CC cells. The expression of epithelial-mesenchymal transition (EMT) markers like N-cadherin, Vimentin, Snail and Slug were suppressed in KITENIN knockdown CC cells. Our results indicate that KITENIN is crucial for cholangiocarcinogenesis and it might become a potential therapeutic target for human CC treatment.

Effect of AdipoR agonist in cholangiocarcinoma

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Background: Adiponectin is the key adipokine, which plays an important role in health and disease such as obesity, diabetes, and cancer. Adiponectin is reduced in different tumor types, especially in obesity-related cancer, and recent studies showed that Adiponectin had a potential anti-cancer effect. Obesity is a risk factor for various tumor diseases including cholangiocarcinoma (CC), the second most common primary hepatic cancer. The aim of this study is to investigate for the first time the anti-cancer effect of AdipoR agonist in CC cell lines and a CC engineered mouse model. Methods: Human CC cell lines (TFK-1 and SZ-1) and CC engineered mice (Alb-Cre/KRASG12D/p53L/L) were used to investigate the anti-cancer effects of an AdipoR agonist (2-(4-Benzoylphenoxy)-N-[1-(phenylmethyl)-4-piperidinyl]-acetamide). Cell proliferation, migration, invasion, colony formation, apoptosis assay were applied to evaluate the effect of AdipoR agonist in vitro. In addition, important cancer signalling pathways and targets were analysed by Western Blot. Mice (n = 12) were treated with AdipoR or verhicle and tumor burden and survival were monitored. Results: AdipoR agonist suppressed proliferation, migration, invasion, colony formation and apoptosis in CC cells. AdipoR agonist regulated the expression of different proteins such as EMT markers, pAMPK, pSTAT3, and PARP, which have pivotal functions in cholangiocarcinogenesis. AdipoR agonist also prolonged survival time in a CC engineered mouse model. Conclusions: Our data revealed that AdipoR agonist inhibited successfully cell proliferation, migration, invasion, colony formation and apoptosis in vitro, and prolonged mice survival in vivo through regulation of crucial signaling pathways in cholangiocarcinogenesis. These results suggested that AdipoR agonist might become a new potential candidate for CC treatment in the future.

Deregulation of Apoptosis - Is it Still an Important Issue in Pathogenesis of Chronic Lymphocytic Leukemia?

Chronic lymphocytic leukemia (CLL), a clonal expansion of B CD5+ cells, is the most common type of adult leukemia in western countries. The accumulation of neoplastic B-cells is primarily caused by prolonged life-span of these cells due to deregulation of apoptosis, and only marginally due to a higher proliferation rate. In spite of numerous reports characterizing particular mechanisms of B-CLL cell apoptosis, still relatively little is known about the complex regulation of this process. Therefore, more detailed research is required to understand the complicated mechanisms and regulatory processes of apoptosis in neoplastic B lymphocytes.

Editorial: DNA Damage as a Strategy for Anticancer Chemotherapy

Amongst all currently used drugs in the field of cancer therapy, the most prominent group of agents which induce DNA, damage both directly or indirectly. Intuitively DNA should not be a perfect target for relatively unspecific small molecular weight drugs. However, the current understanding is that not damage per se but cellular response to DNA damage induced by antitumor agents is responsible for their specific targeted effect towards cancer cells in comparison to the normal cells. DNA damaging chemotherapeutics include compounds with diferent activities namely: directly or indirectly induce DNA strand breaks, covalently modify DNA bases, change the chromatin structure and topology by inhibiting chromatin-modifying enzymes. In this special issue of Current Medicinal Chemistry entitled....

Gamma-Secretase Inhibitor IX (GSI) Impairs Concomitant Activation of Notch and Wnt-Beta-Catenin Pathways in CD44+ Gastric Cancer Stem Cells

Cancer stem cells (CSC) are associated with tumor resistance and are characterized in gastric cancer (GC). Studies have indicated that Notch and wnt-beta-catenin pathways are crucial for CSC development. Using CD44⁺ CSCs, we investigated the role of these pathways in GC carcinogenesis. We performed cell proliferation, wound healing, invasion, tumorsphere, and apoptosis assays. Immunoblot analysis of downstream signaling targets of Notch and wnt-beta-catenin were tested after gamma-secretase inhibitor IX (GSI) treatment. Immunohistochemistry, immunofluorescence, and Fluorescence activated cell sorting (FACS) were used to determine CD44 and Hairy enhancer of split-1 (Hes1) expression in human GC tissues. CD44⁺ CSCs were subcutaneously injected into NMR-nu/nu mice and treated with vehicle or GSI. GC patients with expression of CD44 and Hes1 showed overall reduced survival. CD44⁺ CSCs showed high expression of Hes1. GSI treatment showed effective inhibition of cell proliferation, migration, invasion, tumor sphere formation of CD44⁺ CSCs, and induced apoptosis. Importanly, Notch1 was found to be important in mediating a crosstalk between Notch and wnt-beta-catenin in CD44⁺ CSCs. Our study highlights a crosstalk between Notch and wnt-beta-catenin in gastric CD44⁺ CSCs. Expression of CD44 and Hes1 is associated with patient overall survival. GSI could be an alternative drug to treat GC. Stem Cells Translational Medicine 2017;6:819-829.

Correction: Capsaicin Treatment Attenuates Cholangiocarcinoma Carcinogenesis

[This corrects the article DOI: 10.1371/journal.pone.0095605.].

A MYC-aurora kinase A protein complex represents an actionable drug target in p53-altered liver cancer

MYC oncoproteins are involved in the genesis and maintenance of the majority of human tumors but are considered undruggable. By using a direct in vivo shRNA screen, we show that liver cancer cells that have mutations in the gene encoding the tumor suppressor protein p53 (Trp53 in mice and TP53 in humans) and that are driven by the oncoprotein NRAS become addicted to MYC stabilization via a mechanism mediated by aurora kinase A (AURKA). This MYC stabilization enables the tumor cells to overcome a latent G2/M cell cycle arrest that is mediated by AURKA and the tumor suppressor protein p19(ARF). MYC directly binds to AURKA, and inhibition of this protein-protein interaction by conformation-changing AURKA inhibitors results in subsequent MYC degradation and cell death. These conformation-changing AURKA inhibitors, with one of them currently being tested in early clinical trials, suppressed tumor growth and prolonged survival in mice bearing Trp53-deficient, NRAS-driven MYC-expressing hepatocellular carcinomas (HCCs). TP53-mutated human HCCs revealed increased AURKA expression and a positive correlation between AURKA and MYC expression. In xenograft models, mice bearing TP53-mutated or TP53-deleted human HCCs were hypersensitive to treatment with conformation-changing AURKA inhibitors, thus suggesting a therapeutic strategy for this subgroup of human HCCs.

Notch and wnt-beta catenin pathways as targets of γ-secretase inhibitor IX (GSI) mediated therapy in CD44+ gastric cancer (GC) cells

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Background: GC is the second most common cause of cancer related death worldwide. New palliative therapeutic approaches to treat GC are of urgent need. Targeting cancer stem cells (CSC) could be an effective approach to treat GC. Recent studies have indicated that Notch signaling and wnt-beta-catenin pathways are crucial for CSC development. In this study, we mainly focused on inactivation of both Notch and wnt-beta-catenin pathways in CSC CD44+ GC cells using GSI. Methods: For our experiments we have used the GC cell line MKN45, as it showed expression of both targets (CD44,Hes1). For in vitro experiments proliferation, wound healing, invasion and tumorsphere assays were performed to analyze the migration, invasive and tumorigenic potential of CD44+ sorted GC initiating cells after GSI treatment. Western blot analyses of downstream signaling targets of Notch and wnt-beta catenin were tested after GSI treatment. SiRNA experiments for Notch1 and CD44 were also performed in order to confirm the Notch and wnt-beta-catenin pathway crosstalk. For in vivo analysis sorted CD44+ cells were subcutaneously injected into NMRI-nu/numice and were treated with vehicle or GSI. Results: CD44+ sorted MKN45 cells showed high expression of Hes1 as compared to the CD44- cell population. GSI treatment showed effective inhibition of cell proliferation, migration, invasion and tumor sphere formation of CD44+ cells. Interestingly, amongst all Notch receptors, Notch1 was found to be important in mediating the crosstalk between Notch and wnt-beta-catenin signaling cascades in CD44+ GC cells. Moreover, upon silencing of both CD44 and Notch1 by SiRNA showed effective inhibition of downstream targets and reconfirmed the proposed hypothesis of CD44 mediated Notch and wnt/beta-catenin crosstalk in GC cells. Conclusions: Our study highlights the crosstalk between Notch and wnt-beta-catenin in GC CD44+ cells. GSI could be an alternative drug to treat human GC as it effectively targets the CD44+ GC cells thus, completely reducing all the chances of relapse and metastasis associated with GC. Therefore, GSI therapy can open up new avenues for GC treatment with improved / better clinical outcome.

Treatment of pancreatic ductal adenocarcinoma (PDAC) by argyrin F (AF) + gemcitabine (G)

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Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a 5-year survival rate of < 5%. Early diagnosis is rare and treatment options are often limited. Recent studies have reported that the proteasome inhibitor Argyrin A, a cyclic peptide derived from the myxobacterium Archangium gephyra, shows antitumoral activities. The aim of the present study is to explore the anti-tumor activity of this analogue Argyrin F (AF) + Gemcitabine (G) in PDAC carcinogenesis. Methods: We analyzed the effect of AF on proliferation and epithelial plasticity of different human pancreatic cancer cell lines by using MTT-, wound healing-, invasion-, colony formation-, apoptosis- and senescence assay, as well as cell cycle analysis and Western Blot. In vivo, we assessed the effects of AF and combinational (AF + G) therapy in a genetically engineered mouse model (Pdx1- Cre; LSL-KrasG12D; p53 lox/+) of PDAC. Results: AF inhibited pancreatic cancer cell proliferation, migration, invasion and colony formation compared to their respective untreated controls (DMSO). We also found that AF impairs epithelial-mesenchymal-transition (EMT) and induces considerable apoptosis and senescence in a dose-and time-dependent manner. AF application resulted in cell cycle G1/S phase transition. Most importantly, double treatment by AF + G showed prolonged survival and caused significant tumor reduction. Expression of Ki67 (anti-proliferative marker) and CD34 (tumor angiogenesis marker) was reduced both after AF and AF + G treatment of PDAC tumors in mice. Conclusions: Our work demonstrates that treatment with AF can successfully inhibit the growth of PDAC cells and combinational treatment with AF + G might be also a new and promising combinational therapy for human PDAC treatment.

Targeting c-MET by LY2801653 for treatment of cholangiocarcinoma

Palliative treatment options for human cholangiocarcinoma (CCC) are quite limited and new therapeutic strategies are of utmost need. c-MET has been shown to be deregulated in many cancers, but the role of c-MET in the carcinogenesis of CCC remains unclear. The main purpose of this study is to evaluate the expression and also to investigate the role of c-MET and its effective inhibition for the treatment of CCC. In this study we investigated the effects of LY2801653, a small-molecule inhibitor with potent activity against MET kinase, in human CCC cell lines and in vivo using a xenograft mouse model. We have investigated the role of c-MET and its inhibitory effects on migration, invasion, colony formation, MET downstream targets, and CCC tumor growth. We also analyzed the role of apoptosis and senescence as well as the influence of hypoxia in this context. c-MET and p-MET were expressed in 72% and 12.5% of human CCC tissues and in TFK-1, SZ-1 cell lines. MET inhibition was achieved by blocking phosphorylation of MET with LY2801653 and subsequent down regulation of c-MET downstream targets. Treatment showed in a xenograft model potent anti-tumor activity. LY2801653 is an effective inhibitor and suppress the proliferation of CCC cells as well as the growth of xenograft tumors. Therefore, inhibition of c-MET could be a possible alternative approach for the treatment of human CCC. © 2016 Wiley Periodicals, Inc.

Capsaicin treatment attenuates cholangiocarcinoma carcinogenesis

Capsaicin, the most abundant pungent molecule produced by pepper plants, represents an important ingredient in spicy foods consumed throughout the world. Studies have shown that capsaicin can relieve inflammation and has anti-proliferative effects on various human malignancies. Cholangiocarcinoma (CC) is a cancer disease with rising incidence. The prognosis remains dismal with little advance in treatment. The aim of the present study is to explore the anti-tumor activity of capsaicin in cultured human CC cell lines. Capsaicin effectively impaired cell proliferation, migration, invasion, epithelial to mesenchymal transition and growth of softagar colonies. Further, we show that capsaicin treatment of CC cells regulates the Hedgehog signaling pathway.

CONCLUSION

Our results provide a basis for capsaicin to improve the prognosis of CCs in vivo and present new insights into the effectiveness and mode of action of capsaicin.

Baceridin, a cyclic hexapeptide from an epiphytic bacillus strain, inhibits the proteasome

A new cyclic hexapeptide, baceridin (1), was isolated from the culture medium of a plant-associated Bacillus strain. The structure of 1 was elucidated by HR-HPLC-MS and 1D and 2D NMR experiments and confirmed by ESI MS/MS sequence analysis of the corresponding linear hexapeptide 2. The absolute configurations of the amino acid residues were determined after derivatization by GC-MS and Marfey's method. The cyclopeptide 1 consists partially of nonribosomal-derived D- and allo-D-configured amino acids. The order of the D- and L-leucine residues within the sequence cyclo(-L-Trp-D-Ala-D-allo-Ile-L-Val-D-Leu-L-Leu-) was assigned by total synthesis of the two possible stereoisomers. Baceridin (1) was tested for antimicrobial and cytotoxic activity and displayed moderate cytotoxicity (1-2 μg mL(-1)) as well as weak activity against Staphylococcus aureus. However, it was identified to be a proteasome inhibitor that inhibits cell cycle progression and induces apoptosis in tumor cells by a p53-independent pathway.

A critical role for notch signaling in the formation of cholangiocellular carcinomas

The incidence of cholangiocellular carcinoma (CCC) is increasing worldwide. Using a transgenic mouse model, we found that expression of the intracellular domain of Notch 1 (NICD) in mouse livers results in the formation of intrahepatic CCCs. These tumors display features of bipotential hepatic progenitor cells, indicating that intrahepatic CCC can originate from this cell type. We show that human and mouse CCCs are characterized by high expression of the cyclin E protein and identified the cyclin E gene as a direct transcriptional target of the Notch signaling pathway. Intriguingly, blocking γ-secretase activity in human CCC xenotransplants results in downregulation of cyclin E expression, induction of apoptosis, and tumor remission in vivo.

The intestinal microbiota dysbiosis and Clostridium difficile infection: is there a relationship with inflammatory bowel disease?

Gut microbiota is a compilation of microorganisms dwelling in the entire mammalian gastrointestinal tract. They display a symbiotic relationship with the host contributing to its intestinal health and disease. Even a slight fluctuation in this equipoise may be deleterious to the host, leading to many pathological conditions like Clostridium difficile infection or inflammatory bowel disease (IBD). In this review, we focus on the role of microbial dysbiosis in initiation of C. difficile infection and IBD, and we also touch upon the role of specific pathogens, particularly C. difficile, as causative agents of IBD. We also discuss the molecular mechanisms activated by C. difficile that contribute to the development and exacerbation of gastrointestinal disorders.

Epithelial mesenchymal transition and pancreatic tumor initiating CD44+/EpCAM+ cells are inhibited by γ-secretase inhibitor IX

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a high rate of metastasis. Recent studies have indicated that the Notch signalling pathway is important in PDAC initiation and maintenance, although the specific cell biological roles of the pathway remain to be established. Here we sought to examine this question in established pancreatic cancer cell lines using the γ-secretase inhibitor IX (GSI IX) to inactivate Notch. Based on the known roles of Notch in development and stem cell biology, we focused on effects on epithelial mesenchymal transition (EMT) and on pancreatic tumor initiating CD44+/EpCAM+ cells. We analyzed the effect of the GSI IX on growth and epithelial plasticity of human pancreatic cancer cell lines, and on the tumorigenicity of pancreatic tumor initiating CD44+/EpCAM+ cells. Notably, apoptosis was induced after GSI IX treatment and EMT markers were selectively targeted. Furthermore, under GSI IX treatment, decline in the growth of pancreatic tumor initiating CD44+/EpCAM+ cells was observed in vitro and in a xenograft mouse model. This study demonstrates a central role of Notch signalling pathway in pancreatic cancer pathogenesis and identifies an effective approach to inhibit selectively EMT and suppress tumorigenesis by eliminating pancreatic tumor initiating CD44+/EpCAM+ cells.

Characterization of Virulence Factors of Staphylococcus aureus: Novel Function of Known Virulence Factors That Are Implicated in Activation of Airway Epithelial Proinflammatory Response

Airway epithelial cells play a major role in initiating inflammation in response to bacterial pathogens. S. aureus is an important pathogen associated with activation of diverse types of infection characterized by inflammation dominated by polymorphonuclear leukocytes. This bacterium frequently causes lung infection, which is attributed to virulence factors. Many of virulence determinants associated with S. aureus-mediated lung infection have been known for several years. In this paper, we discuss recent advances in our understanding of known virulence factors implicated in pneumonia. We anticipate that better understanding of novel functions of known virulence factors could open the way to regulate inflammatory reactions of the epithelium and to develop effective strategies to treat S. aureus-induced airway diseases.

H2AX Phosphorylation: Its Role in DNA Damage Response and Cancer Therapy

Double-strand breaks (DSBs) are the most deleterious DNA lesions, which, if left unrepaired, may have severe consequences for cell survival, as they lead to chromosome aberrations, genomic instability, or cell death. Various physical, chemical, and biological factors are involved in DSB induction. Cells respond to DNA damage by activating the so-called DNA damage response (DDR), a complex molecular mechanism developed to detect and repair DNA damage. The formation of DSBs triggers activation of many factors, including phosphorylation of the histone variant H2AX, producing gammaH2AX. Phosphorylation of H2AX plays a key role in DDR and is required for the assembly of DNA repair proteins at the sites containing damaged chromatin as well as for activation of checkpoints proteins which arrest the cell cycle progression. In general, analysis of gammaH2AX expression can be used to detect the genotoxic effect of different toxic substances. When applied to clinical samples from cancer patients, evaluation of gammaH2AX levels may allow not only to monitor the efficiency of anticancer treatment but also to predict of tumor cell sensitivity to DNA damaging anticancer agents and toxicity of anticancer treatment toward normal cells.

Dual inhibition of PI3K/Akt signaling and the DNA damage checkpoint in p53-deficient cells with strong survival signaling: implications for cancer therapy

Natural (intrinsic) resistance of many tumor types to DNA damaging agents is closely associated with their capacity to undergo robust cell cycle arrest in G(2)/M. G(2) arrest is regulated by the DNA damage checkpoint and by survival signaling, with a potential role of PI3K/Akt in checkpoint function. In this work, we wanted to clarify if inhibition of multiple checkpoint/survival pathways may confer better efficacy in the potentiation of genotoxic agents compared to inhibition of either pathway alone. We compared the influence of UCN-01, which affects both the DNA damage checkpoint and PI3K/Akt-mediated survival signaling, with the PI3K inhibitors wortmannin and LY294002 in p53-deficient M1 acute myeloid leukemia cells treated with the DNA damaging agent cisplatin. Our results show that direct inhibition of PI3K/Akt in G(2)-arrested cells by wortmannin or LY294002 strongly enhanced the cytotoxicity of cisplatin without influencing the G(2) checkpoint. Unexpectedly, dual inhibition of both survival and checkpoint signaling by UCN-01, also increased the cytotoxicity of cisplatin, but to a lesser degree than wortmannin or LY294002. The differences in cytotoxicity were accompanied by differences in cell death pathways: direct inhibition of PI3K/Akt was accompanied by rapid apoptotic cell death during G(2), whereas cells underwent mitotic transit and cell division followed by cell death during G(1) when both checkpoint and survival signaling were inhibited. Our results elucidate a novel function for PI3K/Akt as a survival factor during DNA damage-induced G(2) arrest and could have important pharmacological consequences for the application of response modulators in p53-deficient tumors with strong survival signaling.

Specific role of the SR protein splicing factor B52 in cell cycle control in Drosophila

E2F and retinoblastoma tumor suppressor protein pRB are important regulators of cell proliferation; however, the regulation of these proteins in vivo is not well understood. In Drosophila there are two E2F genes, an activator, de2f1, and a repressor, de2f2. The loss of de2f1 gives rise to the G(1)/S block accompanied by the repression of E2F-dependent transcription. These defects can be suppressed by mutation of de2f2. In this work, we show that the de2f1 mutant phenotype is rescued by the loss of the pre-mRNA splicing factor SR protein B52. Mutations in B52 restore S phase in clones of de2f1 mutant cells and phenocopy the loss of the de2f2 function. B52 acts upstream of de2f2 and plays a specific role in regulation of de2f2 pre-mRNA splicing. In B52-deficient cells, the level of dE2F2 protein is severely reduced and the expression of dE2F2-dependent genes is deregulated. Reexpression of the intronless copy of dE2F2 in B52-deficient cells restores the dE2F2-mediated repression. These results uncover a previously unrecognized role of the splicing factor in maintaining the G(1)/S block in vivo by specific regulation of the dE2F2 repressor function.

Cross-talk between DNA damage and cell survival checkpoints during G2and mitosis: pharmacologic implications

In this study, we wanted to clarify the role of survivin-mediated survival signaling during G2 and M in tumor cells treated with DNA-damaging agents. As a cellular model, we selected MOLT-4 human T-cell lymphoblastic leukemia cells that overexpress survivin and nonfunctional p53. Treatment with melphalan, a classic DNA-damaging agent, led to the induction of the DNA damage checkpoint and growth arrest in the G2 phase of the cell cycle. Checkpoint abrogation by caffeine was accompanied by mitotic entry and rapid apoptotic cell death, whereas cells remaining in G2 remained viable during the same time interval. Unexpectedly, when the spindle checkpoint was activated following G2 abrogation, two different effects could be observed. If the microtubules of the melphalan-treated cells were destabilized by nocodazole, cells became arrested in prometaphase with low survivin levels and entered apoptosis. In contrast, if the microtubules of the melphalan-treated cells were stabilized by taxol, cells were still arrested in prometaphase, but apoptotic execution was inhibited. This effect is, most likely, directly mediated by survivin itself given its well-established antiapoptotic functions. In conclusion, depending on the way the spindle checkpoint was activated in cells with damaged DNA, cells could be either protected by survivin or die during mitosis. We suggest that the efficacy of DNA damage checkpoint abrogators used in combination with DNA-damaging agents may critically depend on whether DNA damage is able to invoke spindle checkpoint response and to activate survivin-associated survival signaling during mitosis.

Antitumour imidazoacridone C-1311 induces cell death by mitotic catastrophe in human colon carcinoma cells

In this study, we investigated the cell death process induced by imidazoacridone C-1311 (Symadex) in HT-29 human colon carcinoma cells which have been shown to be preferentially sensitive to this compound in experimental tumour models both in vitro and in nude mice. Compound C-1311 at the EC(99) dose delayed progression of cells through the S phase which was followed by G2 arrest. At 48-96 h after drug exposure, an increasing fraction of cells rounded up and detached from the substratum which suggested the induction of cell death. This was confirmed by the induction of DNA fragmentation as revealed by pulse field electrophoresis and DNA strand breaks by the TUNEL assay. The dying cells had also mitotic features which were evidenced by various biochemical and morphological criteria such as activation of Cdk1 kinase, presence of the mitotic epitope MPM-2 and condensation of chromatin into mitotic chromosomes in drug-treated cells. These results show that C-1311 does not induce rapid apoptosis in HT-29 cells, instead drug exposure leads to prolonged G2 arrest followed by G2 to M transit and cell death during mitosis in the process of mitotic catastrophe.

Small molecule RITA binds to p53, blocks p53-HDM-2 interaction and activates p53 function in tumors

In tumors that retain wild-type p53, its tumor-suppressor function is often impaired as a result of the deregulation of HDM-2, which binds to p53 and targets it for proteasomal degradation. We have screened a chemical library and identified a small molecule named RITA (reactivation of p53 and induction of tumor cell apoptosis), which bound to p53 and induced its accumulation in tumor cells. RITA prevented p53-HDM-2 interaction in vitro and in vivo and affected p53 interaction with several negative regulators. RITA induced expression of p53 target genes and massive apoptosis in various tumor cells lines expressing wild-type p53. RITA suppressed the growth of human fibroblasts and lymphoblasts only upon oncogene expression and showed substantial p53-dependent antitumor effect in vivo. RITA may serve as a lead compound for the development of an anticancer drug that targets tumors with wild-type p53.

Rescue of mutants of the tumor suppressor p53 in cancer cells by a designed peptide

We designed a series of nine-residue peptides that bound to a defined site on the tumor suppressor p53 and stabilized it against denaturation. To test whether the peptides could act as chaperones and rescue the tumor-suppressing function of oncogenic mutants of p53 in living cells, we treated human tumor cells with the fluorescein-labeled peptide Fl-CDB3 (fluorescent derivative of CDB3). Before treatment, the mutant p53 in the cell was predominantly denatured. Fl-CDB3 was taken up into the cytoplasm and nucleus and induced a substantial up-regulation of wild-type p53 protein and representative mutants. The mutants, His-273 and His-175 p53, adopted the active conformation, with a dramatic decrease in the fraction of denatured protein. In all cases, there was p53-dependent induction of expression of the p53 target genes mdm2, gadd45, and p21, accompanied by p53-dependent partial restoration of apoptosis. Fl-CDB3 sensitized cancer cells that carried wild-type p53 to p53-dependent gamma-radiation-induced apoptosis. Although Fl-CDB3 did not elicit a full biological response, it did bind to and rescue p53 in cells and so can serve as a lead for the development of novel drugs for anticancer therapy.

Influence of G2 arrest on the cytotoxicity of DNA topoisomerase inhibitors toward human carcinoma cells with different p53 status

We here report the influence of the cell cycle abrogator UCN-01 on RKO human colon carcinoma cells differing in p53 status following exposure to two DNA damaging agents, the topoisomerase inhibitors etoposide and camptothecin. Cells were treated with the two drugs at the IC90 concentration for 24 h followed by post-incubation in drug-free medium. RKO cells expressing wild-type, functional p53 arrested the cell cycle progression in both the G1 and G2 phases of the cell cycle whereas the RKO/E6 cells, which lack functional p53, only arrested in the G2 phase. Growth-arrested cells did not resume proliferation even after prolonged incubation in drug-free medium (up to 96 h). To evaluate the importance of the cell cycle arrest on cellular survival, a non-toxic dose of UCN-01 (100 nM) was added to the growth-arrested cells. The addition of UCN-01 was accompanied by mitotic entry as revealed by the appearance of condensed chromatin and the MPM-2 phosphoepitope, which is characteristic for mitotic cells. G2 exit and mitotic transit was accompanied by a rapid activation of caspase-3 and apoptotic cell death. The influence of UCN-01 on the long-term cytotoxic effects of the two drugs was also determined. Unexpectedly, abrogation of the G2 arrest had no influence on the overall cytotoxicity of either drug. In contrast, addition of UCN-01 to cisplatin-treated RKO and RKO/E6 cells greatly increased the cytotoxic effects of the alkylating agent. These results strongly suggest that even prolonged cell cycle arrest in the G2 phase of the cell cycle is not necessarily coupled to efficient DNA repair and enhanced cellular survival as generally believed.

Influence of G2 arrest on the cytotoxicity of DNA topoisomerase inhibitors toward human carcinoma cells with different p53 status

We here report the influence of the cell cycle abrogator UCN-01 on RKO human colon carcinoma cells differing in p53 status following exposure to two DNA damaging agents, the topoisomerase inhibitors etoposide and camptothecin. Cells were treated with the two drugs at the IC90 concentration for 24 h followed by post-incubation in drug-free medium. RKO cells expressing wild-type, functional p53 arrested the cell cycle progression in both the G1 and G2 phases of the cell cycle whereas the RKO/E6 cells, which lack functional p53, only arrested in the G2 phase. Growth-arrested cells did not resume proliferation even after prolonged incubation in drug-free medium (up to 96 h). To evaluate the importance of the cell cycle arrest on cellular survival, a non-toxic dose of UCN-01 (100 nM) was added to the growth-arrested cells. The addition of UCN-01 was accompanied by mitotic entry as revealed by the appearance of condensed chromatin and the MPM-2 phosphoepitope, which is characteristic for mitotic cells. G2 exit and mitotic transit was accompanied by a rapid activation of caspase-3 and apoptotic cell death. The influence of UCN-01 on the long-term cytotoxic effects of the two drugs was also determined. Unexpectedly, abrogation of the G2 arrest had no influence on the overall cytotoxicity of either drug. In contrast, addition of UCN-01 to cisplatin-treated RKO and RKO/E6 cells greatly increased the cytotoxic effects of the alkylating agent. These results strongly suggest that even prolonged cell cycle arrest in the G2 phase of the cell cycle is not necessarily coupled to efficient DNA repair and enhanced cellular survival as generally believed.