Repression of Nrf2 enhances antitumor effect of 5-fluorouracil and gemcitabine on cholangiocarcinoma cells

The molecular mechanisms and targeting strategies of transcription factors in cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma consists of a cluster of malignant biliary tumors that tend to have a poor prognosis, ranking as the second most prevalent type of liver cancer, and their incidence rate has increased globally recently. The high-frequency driving mutations of cholangiocarcinoma, such as KRAS/IDH1/ARID1A/P53, imply the epigenetic instability of cholangiocarcinoma, leading to the dysregulation of various related transcription factors, thus affecting the occurrence and development of cholangiocarcinoma. Increasingly evidence indicates that the high heterogeneity and malignancy of cholangiocarcinoma are closely related to the dysregulation of transcription factors which promote cell proliferation, invasion, migration, angiogenesis, and drug resistance through reprogrammed transcriptional networks. It is of great significance to further explore and summarize the role of transcription factors in cholangiocarcinoma.

AREAS COVERED

This review summarizes the oncogenic or tumor suppressive roles of key transcription factors in regulating cholangiocarcinoma progression and the potential targeting strategies of transcription factors in cholangiocarcinoma.

EXPERT OPINION

Cholangiocarcinoma is a type of cancer highly influenced by transcriptional regulation, specifically transcription factors and epigenetic regulatory factors. Targeting transcription factors could be a potential and important strategy that is likely to impact future cholangiocarcinoma treatment.

Aggregation-induced emission photosensitizer-based photodynamic therapy in cancer: from chemical to clinical

Cancer remains a serious threat to human health owing to the lack of effective treatments. Photodynamic therapy (PDT) has emerged as a promising non-invasive cancer treatment that consists of three main elements: photosensitizers (PSs), light and oxygen. However, some traditional PSs are prone to aggregation-caused quenching (ACQ), leading to reduced reactive oxygen species (ROS) generation capacity. Aggregation-induced emission (AIE)-PSs, due to their distorted structure, suppress the strong molecular interactions, making them more photosensitive in the aggregated state instead. Activated by light, they can efficiently produce ROS and induce cell death. PS is one of the core factors of efficient PDT, so proceeding from the design and preparation of AIE-PSs, including how to manipulate the electron donor (D) and receptor (A) in the PSs configuration, introduce heavy atoms or metal complexes, design of Type I AIE-PSs, polymerization-enhanced photosensitization and nano-engineering approaches. Then, the preclinical experiments of AIE-PSs in treating different types of tumors, such as ovarian cancer, cervical cancer, lung cancer, breast cancer, and its great potential clinical applications are discussed. In addition, some perspectives on the further development of AIE-PSs are presented. This review hopes to stimulate the interest of researchers in different fields such as chemistry, materials science, biology, and medicine, and promote the clinical translation of AIE-PSs.

Nrf2 antioxidant pathway and apoptosis induction and inhibition of NF-κB-mediated inflammatory response in human prostate cancer PC3 cells by Brassica oleracea var. acephala: An in vitro study

BACKGROUND

Brassica oleracea var. acephala is a good source of health-promoting biologically active compounds like phenolics, vitamins, and glucosinolates.

METHODS AND RESULTS

This in vitro research was conducted to evaluate the apoptotic, antioxidant, anti-inflammatory, and antiproliferative properties of ethanolic extract of Brassica oleracea var. acephala (EEBO) in PC3 prostate cancer cells. The LC-MS/MS technique was applied to identify the biomolecules of EEBO. The MTT assay was used to evaluate the cytotoxic effects of EEBO on PC3 cells. Moreover, qRT-PCR was used to examine the expression levels of Nrf2, NQO1, HO-1, NF-κB, TNF-α, IL-6, BAX, and BCL-2 in PC3 cell line. MMP was predicted by Rhodamine 123 staining, and release of cytochrome c was detected by an ELISA kit. Further, apoptosis was quantified by DNA fragmentation assay. The Western blotting method was used to detect the protein expression levels, and The DPPH assay was applied to determine the antioxidant effect of EEBO. The formula and structure of 19 biomolecules were predicted by LC-MS/MS. EEBO exhibited scavenging activity for DPPH. The MTT test showed EEBO reduced the viability of PC3 cells. The mRNA and protein levels of NRF2 pathway genes and BAX were increased, but those of the NF-κB pathway genes and BCL-2 were decreased in the EEBO-treated cells. Moreover, EEBO led to the diminution of MMP and enhanced the release of cytochrome c and DNA fragmentation, which resulted in apoptosis.

CONCLUSIONS

Molecular changes due to the anticancer impact of EEBO on PC3 were involved in the induction of Nrf2 antioxidant pathway and apoptosis and inhibition of inflammation.

The Effect of the EGFR - Targeting Compound 3-[(4-Phenylpyrimidin-2-yl) Amino] Benzene-1-Sulfonamide (13f) against Cholangiocarcinoma Cell Lines

OBJECTIVE

Cholangiocarcinoma (CCA) is a noxious malignancy of epithelium of the bile duct with a low response rate to chemotherapy. The epidermal growth factor receptor (EGFR) signaling pathway is implicated in the development of cancerous cells, especially CCA. In this study, we report detailed biological profiling of 13f identified from our earlier hit expansion studies. The aim of this work was to expand our understanding of 13f via more detailed investigations of its mechanism of action against KKU-100, KKU-452 and KKU-M156 CCA cells, as well as in comparison to the EGFR inhibitor Gefitinib and non-specific chemotherapeutic agents such as Cisplatin.

METHODS

Inhibiting EGFR-Kinase, cytotoxicity, clonogenic assay, wound healing and apoptosis were performed. Levels of total expression of EGFR and EGFR phosphorylation proteins were detected.

RESULTS

13f was confirmed as an inhibitor of EGFR with an IC50 value against the tyrosine kinase of EGFR of 22 nM and IC50 values for 48 h incubation period were 1.3 ± 1.9, 1.5 ± 0.4 and 1.7 ± 1.1 µM of KKU-100, KKU-452 and KKU-M156, respectively through dose- and time-dependent induction of early apoptosis of CCA cells. The compound also suppressed the clonogenic ability of KKU-100 and KKU-M156 cells stronger than Gefitinib, while potently inhibiting EGF-stimulated CCA cell migratory activity in KKU-452 cells. It was observed that under normal conditions EGFR was activated in CCA cells. EGF-stimulated basal expression of EGFR in KKU-452 cells was suppressed following 13f treatment, which was significantly greater than that of the marketed EGFR inhibitor Gefitinib.

CONCLUSION

In summary, our study showed that 13f has potent anti-cancer activities including antiproliferation, clonogenic ability and migration through the modulation of EGFR signaling pathway in CCA for the first time. The compound represents an interesting starting point as a potential chemotherapeutic agent in ongoing efforts to improve response rate in CCA patients.
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Nuclear Factor Erythroid 2-Related Factor 2 in Regulating Cancer Metabolism

Significance: Nuclear factor erythroid 2 (NFE2)-related factor 2 (NFE2L2, or NRF2) is a transcription factor predominantly affecting the expression of antioxidant genes. NRF2 plays a significant role in the control of redox balance, which is crucial in cancer cells. NRF2 activation regulates numerous cancer hallmarks, including metabolism, cancer stem cell characteristics, tumor aggressiveness, invasion, and metastasis formation. We review the molecular characteristics of the NRF2 pathway and discuss its interactions with the cancer hallmarks previously listed. Recent Advances: The noncanonical activation of NRF2 was recently discovered, and members of this pathway are involved in carcinogenesis. Further, cancer-related changes (e.g., metabolic flexibility) that support cancer progression were found to be redox- and NRF2 dependent. Critical Issues: NRF2 undergoes Janus-faced behavior in cancers. The pro- or antineoplastic effects of NRF2 are context dependent and essentially based on the specific molecular characteristics of the cancer in question. Therefore, systematic investigation of NRF2 signaling is necessary to clarify its role in cancer etiology. The biggest challenge in the NRF2 field is to determine which cancers can be targeted for better clinical outcomes. Further, large-scale genomic and transcriptomic studies are missing to correlate the clinical outcome with the activity of the NRF2 system. Future Directions: To exploit NRF2 in a clinical setting in the future, the druggable members of the NRF2 pathway should be identified. In addition, it will be important to study how the modulation of the NRF2 system interferes with cytostatic drugs and their combinations.

Variants in oxidative stress-related genes affect the chemosensitivity through Nrf2-mediated signaling pathway in biliary tract cancer

BACKGROUND

Oxidative stress and their effectors play critical roles in carcinogenesis and chemoresistance. However, the role of oxidative stress-related genes variants in biliary tract cancer (BTC) chemoresistance remains unknown. In this work, we aim to investigate oxidative stress-dependent molecular mechanisms underlying chemoresistance, and find potential biomarkers to predict chemotherapy response for BTC.

METHODS

Sixty-six SNPs in 21 oxidative stress-related genes were genotyped and analyzed in 367 BTC patients. Immunoblot, immunohistochemical, immunofluorescent, quantitative PCR, chromatin immunoprecipitation analysis and study of animal xenograft models were performed to discover oxidative stress-related susceptibility genes underlying chemoresistance mechanism of BTC.

FINDINGS

We found that 3 functional polymorphisms (CAT_rs769217, GPX4_rs4807542, and GSR_rs3779647), which were shown to affect their respective gene expression levels, modified the effect of chemotherapy on overall survival (OS). We then demonstrated that knockdown of GPX4, CAT, or GSR induced chemoresistance through elevation of ROS level and activation of Nrf2-ABCG2 pathway in BTC cell lines. Moreover, the association between Nrf2 expression and BTC prognosis is only found in patients who received chemotherapy. Knockdown of Nrf2 enhanced chemosensitivity or even eliminated postoperative recurrence in BTC xenograft mouse models. Importantly, upon chemotherapy treatment patients harboring high oxidative stress-related score received higher survival benefit from adjuvant chemotherapy compared with patients with low oxidative stress-related score.

INTERPRETATION

The result of our study suggests, for the first time, that the oxidative stress-related score calculated by combining variations in CAT, GPX4, and GSR or Nrf2 expression could be used for predicting the chemosensitivity of BTC patients. FUND: This work was supported by the National Science Foundation of China, Foundation of Shanghai Shen Kang Hospital Development Center, and Shanghai Outstanding Academic Leaders Plan.

Effect of the Nrf2-ARE signaling pathway on biological characteristics and sensitivity to sunitinib in renal cell carcinoma

The aim of the present study was to examine the effects of the nuclear factor erythroid-2 related factor 2-antioxidant-responsive element (Nrf2-ARE) signaling pathway on the biological characteristics and sensitivity to targeted therapy in human renal cell carcinoma (RCC) cells. RCC tissues and adjacent tissues were collected and assessed by immunohistochemistry to determine the expression of Nrf2, NAD(P)H dehydrogenase [quinone] 1 (NQO1) and heme oxygenase-1 (HO-1) to analyze the clinicopathological features of RCC. A series of in vitro experiments were conducted to analyze the biological characteristics of Nrf2-ARE signaling in RCC. The renal cancer cell line, 786-0 was used, and cells was divided into a mock group, negative control group and small hairpin (sh)RNA-Nrf2 group. A Cell Counting Kit-8 assay was performed alongside flow cytometry to detect cell viability, cell cycle stage and apoptosis following treatment with sunitinib. The results demonstrated that Nrf2, NQO1 and HO-1 were significantly upregulated in RCC tissues compared with adjacent tissues and were associated with tumor node metastasis stage, Fuhrman classification and lymph node metastasis. Following shRNA-Nrf2 transfection, the 786-0 cells demonstrated a significant decrease in viability, cell invasion and scratch healing rate, and the mRNA and protein expression levels of Nrf2, NQO1, HO-1 and glutathione transferase were significantly decreased, which enhanced the sensitivity to sunitinib, arrested cells in the G0/G1 phase and increased apoptosis. In conclusion, Nrf2-ARE signaling is important for RCC progression, and its inhibition may increase sensitivity to targeted drugs to provide novel developments for RCC treatment.

Metformin sensitizes cholangiocarcinoma cell to cisplatin-induced cytotoxicity through oxidative stress mediated mitochondrial pathway

AIMS

Metformin (Met), an essential antidiabetic agent, shows antitumor activity in some cancers. A previous study showed that Met enhanced cytotoxic activity of cisplatin (Cis) in cholangiocarcinoma (CCA) in association with the activation of AMP-activated protein kinase and suppression of Akt-mTOR. However, these effects do not entirely explain the observed chemosensitizing effect. The present study investigated the interaction of Met and Cis over the enhanced antitumor effect.

MAIN METHODS

KKU-100 and KKU-M156 cells were used in the study. Cytotoxicity was assessed by acridine orange-ethidium bromide staining. Reactive oxygen species (ROS) and mitochondrial transmembrane potential (Δψm) were measured by dihydroethidium and JC-1 fluorescent methods. Cellular glutathione (GSH) and redox ratio were analyzed by enzymatic coupling assay. Proteins associated with antioxidant system and cell death were evaluated by western immunoblot.

KEY FINDINGS

Cytotoxicity of Cis was enhanced by Met in association with ROS formation and GSH redox stress. The antioxidants, N-acetylcysteine and TEMPOL, and MPTP inhibitor, cyclosporine, attenuated cytotoxicity in association with suppression of ROS formation and the losses of Δψm. Met in combination with Cis suppressed expression of Nrf2 and altered the expression of Bcl2 family proteins.

SIGNIFICANCE

The chemosensitizing effect of Met in combination with Cis is causally associated with increased oxidative stress-mediated mitochondrial cell death pathway. Met may improve the efficacy of Cis in the treatment of cancer.

Suppression of Nrf2 confers chemosensitizing effect through enhanced oxidant-mediated mitochondrial dysfunction

AIMS

Transcription factor Nrf2, which regulates the expression of cytoprotective and antioxidant enzymes, contributes to proliferation and resistance to chemotherapy in cancer. The inhibition of Nrf2 can sensitize cholangiocarcinoma (CCA) cells to the cytotoxicity of several chemotherapeutic agents. In this study, we investigated the mechanism of this chemosensitizing effect.

MAIN METHODS

KKU-100 cells were used in the study. Nrf2 expression was knocked down by siRNA and expression was validated by reverse transcription and polymerase chain reaction. Cytotoxicity was assessed by sulforhodamine B method. Intracellular reactive oxygen species (ROS) was examined by fluorescent dye, dichlorofluorescin diacetate method and mitochondrial transmembrane potential was assessed by JC1 dye assay.

KEY FINDINGS

Cytotoxicity of cisplatin (Cis) in KKU-100 cells was enhanced by knockdown of Nrf2 expression. The enhanced cytotoxic effect was abolished by treatment with N-acetylcysteine, TEMPOL and MnTBAP. Cells with Nrf2 knockdown or Cis treatment increased production of ROS, and ROS was markedly enhanced by a combination of Nrf2 knockdown and Cis. The increased ROS formation was associated with a decrease in mitochondrial transmembrane potential (Δψm), where this decrease was prevented by antioxidant compounds. The loss of Δψm and cell death were prevented by cyclosporine, an inhibitor of mitochondrial permeability transition pore (MPTP). Luteolin inhibited Nrf2 and markedly enhanced cytotoxicity in combination with Cis.

SIGNIFICANCE

Inhibition of Nrf2 is a feasible strategy in enhancing antitumor activity of chemotherapeutic agents and improving efficacy of chemotherapy in CCA.

Downregulation of NAD(P)H:quinone oxidoreductase 1 inhibits proliferation, cell cycle and migration of cholangiocarcinoma cells

We previously reported that upregulation of NAD(P)H:quinone oxidoreductase 1 (NQO1) in cholangiocarcinoma (CCA; a fatal bile duct cancer) was associated with poor prognosis. It was also demonstrated that the suppression of NQO1 was able to enhance the chemosensitivity of CCA cells. In the present study, in order to elucidate the biological role of NQO1 in CCA, the effects of small interfering RNA (siRNA)-mediated knockdown of NQO1 on cell proliferation, cell cycle and migration were determined in KKU-100 CCA cells, which notably expressed NQO1. The cell proliferation ability and cell cycle distribution were identified by clonogenic cell survival assay and flow cytometric analysis, respectively. Wound healing and Transwell migration assays were performed to evaluate cell migration. The molecules involved in cell proliferation and migration were determined by western blot analysis and reverse transcription-quantitative polymerase chain reaction analysis. The results demonstrated that NQO1 siRNA-mediated knockdown effectively impaired colony formation capacity, induced cell cycle arrest at the G1 phase and suppressed migration of KKU-100 cells. CCA cells transfected with NQO1 siRNA exhibited increased expression levels of p21 and decreased cyclin D1 protein expression levels. Furthermore, the ratio of matrix metalloproteinase 9/tissue inhibitors of metalloproteinases 1 (TIMP1) mRNA expression level was decreased in the NQO1-knockdown cells. Therefore, the present study provided evidence supporting the biological role of NQO1 in the regulation of cell proliferation, cell cycle and migration of CCA cells. Therefore, NQO1 may prove to be a potential molecular target to enhance CCA treatment.

Easy-to-use strategy for reference gene selection in quantitative real-time PCR experiments

Real-time PCR is an indispensable technique for mRNA expression analysis but conclusions depend on appropriate reference gene selection. However, while reference gene selection has been a topic of publications, this issue is often disregarded when measuring target mRNA expression. Therefore, we (1) evaluated the frequency of appropriate reference gene selection, (2) suggest an easy-to-use tool for least variability reference gene selection, (3) demonstrate application of this tool, and (4) show effects on target gene expression profiles. All 2015 published articles in Naunyn-Schmiedeberg's Archives of Pharmacology were screened for the use of quantitative real-time PCR analysis and selection of reference genes. Target gene expression (Vegfa, Grk2, Sirt4, and Timp3) in H9c2 cells was analyzed following various interventions (hypoxia, hyperglycemia, and/or isoflurane exposure with and without subsequent hypoxia) in relation to putative reference genes (Actb, Gapdh, B2m, Sdha, and Rplp1) using the least variability method vs. an arbitrarily selected but established reference gene. In the vast majority (18 of 21) of papers, no information was provided regarding selection of an appropriate reference gene. In only 1 of 21 papers, a method of appropriate reference gene selection was described and in 2 papers reference gene selection remains unclear. The method of reference gene selection had major impact on interpretation of target gene expression. With hypoxia, for instance, the least variability gene was Rplp1 and target gene expression (Vefga) heavily showed a 2-fold up-regulation (p = 0.022) but no change (p = 0.3) when arbitrarily using Gapdh. Frequency of appropriate reference gene selection in this journal is low, and we propose our strategy for reference gene selection as an easy tool for proper target gene expression.

Luteolin induces cholangiocarcinoma cell apoptosis through the mitochondrial-dependent pathway mediated by reactive oxygen species

OBJECTIVES

To investigate the apoptosis-inducing effect and underlying mechanisms of luteolin in cholangiocarcinoma (CCA) cells.

METHODS

Cell viability was determined by sulphorhodamine B. Apoptosis was detected using acridine orange/ethidium bromide dye staining and annexin V/PI staining followed by flow cytometry. The effect of luteolin on the oxidative status of CCA cells was evaluated by measuring intracellular reactive oxygen species (ROS) levels using the dihydroethidium method and quantifying glutathione levels. The mitochondria transmembrane potential (ΔΨm) was examined through JC-1 staining. The protein levels were determined by Western blot. Caspase activity was determined using specific fluorogenic substrates.

KEY FINDINGS

Luteolin decreased KKU-100 CCA cells' viability by induction of apoptosis. Luteolin treatment increased ROS production and decreased glutathione levels. These changes were associated with the decrease of Nrf2, γ-glutamylcysteine ligase and heme oxygenase-1 proteins. Moreover, luteolin induced mitochondrial depolarization, which was accompanied by the release of cytochrome c and a decrease of Bcl-2 and Bcl-XL proteins. Pretreatment with antioxidants, 4-hydroxy-TEMPO and N-acetyl-L-cysteine significantly prevented luteolin-induced CCA cell death and loss of ΔΨm. In addition, luteolin induced the activation of caspase-9 and caspase-3.

CONCLUSIONS

Luteolin exerts its pro-apoptotic action partly through generating intracellular ROS that then contributes to the activation of mitochondria-mediated apoptotic cell death.

Nrf2 inhibition sensitizes cholangiocarcinoma cells to cytotoxic and antiproliferative activities of chemotherapeutic agents

Nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor regulating antioxidant, cytoprotective, and metabolic enzymes, plays important roles in drug resistance and proliferation in cancer cells. The present study was aimed to examine the expression of Nrf2 in connection with chemotherapeutic drug sensitivity on cholangiocarcinoma (CCA) cells. The basal levels of Nrf2 protein in cytosol and nuclear fractions of CCA cells were determined using Western blot analysis. Nrf2 mRNA expression of KKU-M156 and KKU-100 cells, representatives of low and high-Nrf2-expressing CCA cells, were silenced using siRNA. After knockdown of Nrf2, the sensitivity of those cells to the cytotoxicity of cisplatin (Cis) was enhanced in association with the increased release of AIF and downregulation of Bcl-xl in both cells. Also, knockdown of Nrf2 suppressed the replicative capability of those cells in colony-forming assay and enhanced their sensitivity to antiproliferative activity of Cis and 5-fluorouracil. The chemosensitizing effect was associated with the suppressed expression of Nrf2-regulated and Cis-induced antioxidant and metabolic genes including NQO1, HO-1, GCLC, TXN, MRP2, TKT, and G6PD. In cell cycle analysis, Nrf2 knockdown cells were arrested at G0/G1 phase and combination with Cis increased the accumulation of cells at S phase. The suppression of KKU-M156 cell proliferation was associated with the downregulation of cyclin D1 and increased level of p21. Inhibition of Nrf2 could be a novel strategy in enhancing antitumor activity of chemotherapeutic agent in control of resistant cancer.

Simvastatin and atorvastatin as inhibitors of proliferation and inducers of apoptosis in human cholangiocarcinoma cells

AIMS

In this study, we investigated whether statins induce human cholangiocarcinoma (CCA) cell death and apoptosis, and examined the mechanism by which statins act on cells.

MAIN METHODS

Four CCA cell lines, KKU-100, KKU-M055, KKU-M214, and KKU-M156 CCA cell lines were examined for HMGCR mRNA expression by the RT-PCR method. Two CCA cell lines, with low and high HMGCR mRNA expression, were used to evaluate the sensitivity to two statins, simvastatin and atorvastatin. Cytotoxic activity, antiproliferative activity, and cell migratory effects of the statins on CCA cells were evaluated using sulforhodamine B (SRB) and acridine orange/ethidium bromide (AO/EB), the colony formation assay, and wound healing assay, respectively. ROS formation was measured and apoptosis-related proteins were analyzed by Western blotting.

KEY FINDINGS

Both statins induced KKU-100 and KKU-M214 cell death in a time- and dose-dependent manner. Statins induced cell death more potently in the KKU-100 cells exhibiting low HMGCR expression than the KKU-M214 cells which had high HMGCR expression. Simvastatin was more potently cytotoxic than atorvastatin with lower IC50 values. Treatment with statins also caused a concentration-dependent decline in colony forming ability and cell migration. Both statins induced reactive oxygen species (ROS) formation in KKU-100 cells, but not in KKU-M214 cells. Simvastatin enhanced the release of cytochrome c, caspase 3, and increased p21 levels, especially for the KKU-100 cells.

SIGNIFICANCE

Statins induced CCA cell death, inhibited cell migration, and induced apoptosis. Cell death was probably induced via the mitochondrial pathway. Statins could potentially be developed as novel chemotherapeutic agents for CCA.

Haem oxygenase 1 expression is associated with prognosis in cholangiocarcinoma patients and with drug sensitivity in xenografted mice

OBJECTIVE

Haem oxygenase-1 (HO-1) plays important roles in cytoprotection and tumour growth. Cholangiocarcinoma (CCA) is a deadly malignancy with very poor prognosis. The role of HO-1 in tumour progression in CCA up to now has been relatively unexplored, thus, its possible therapeutic implications in CCA have been investigated here.

MATERIALS AND METHODS

HO-1 expression in tumour tissues from 50 CCA patients was determined by immunohistochemical analysis and its association with survival time was evaluated using the Kaplan-Meier method. Its role in CCA cells in vitro was evaluated by transwell and wound healing assays and suppression of HO-1 expression by siRNA. Effects of HO-1 inhibition on gemicitabine (GEM)-mediated tumour suppression was evaluated in nude mice xenografted with CCA cells.

RESULTS

HO-1 expression was inversely associated with median overall survival time. Hazard ratio of patients with high HO-1 expression was 2.42 (95% CI: 1.16-5.08) with reference to low expression and HO-1 knock-down expression inhibited transwell cell migration. Suppression of HO-1 by Zn-protoporphyrin (ZnPP) enhanced cytotoxicity to GEM in CCA cells, validated in CCA xenografts. Treatment with GEM and ZnPP almost completely arrested tumour growth, whereas treatment with only a single reagent, retarded it. Tumour inhibition was associated with reduction in expression of Ki-67 and microvascular density, and enhanced p53 and p21 immunohistochemical staining.

CONCLUSION

High HO-1 expression was associated with poor prognosis of CCA. Synergistic role of HO-1 inhibition in chemotherapy of CCA is a promising insight for treatment of this tumour and warrants further investigation.

Induction of MITF expression in human cholangiocarcinoma cells and hepatocellular carcinoma cells by cyclopamine, an inhibitor of the Hedgehog signaling

Microphthalmia-associated transcription factor (MITF) is a key regulator of differentiation of melanocytes and retinal pigment epithelial cells, but it also has functions in non-pigment cells. MITF consists of multiple isoforms, including widely expressed MITF-A and MITF-H. In the present study, we explored the potential role played by the Hedgehog signaling on MITF expression in two common types of primary liver cancer, using human cholangiocarcinoma cell lines, the KKU-100 and HuCCT1, along with the HepG2 human hepatocellular carcinoma cell line. Importantly, cholangiocarcinoma is characterized by the activated Hedgehog signaling. Here we show that MITF-A mRNA is predominantly expressed in all three human liver cancer cell lines examined. Moreover, cyclopamine, an inhibitor of the Hedgehog signalling, increased the expression levels of MITF proteins in HuCCT1 and HepG2 cells, but not in KKU-100 cells, suggesting that MITF expression may be down-regulated in some liver cancer cases.

The greedy nature of mutant RAS: a boon for drug discovery targeting cancer metabolism?

RAS oncogene mutations are frequently detected in human cancers. Among RAS-mediated tumorigenesis, KRAS-driven cancers are the most frequently diagnosed and resistant to current therapies. Despite more than three decades of intensive efforts, there are still no specific therapies for mutant RAS proteins. While trying to block those well-established downstream pathways, such as the RAF-MAPK pathway and the PI3K-AKT pathway, attentions have been paid to potential effects of RAS on metabolic pathways and the feasibility for targeting these pathways. Recent studies have proved that RAS not only promotes aerobic glycolysis and glutamine metabolism reprograming to provide energy, but it also facilitates branched metabolism pathways, autophagy, and macropinocytosis. These alterations generate building blocks for tumor growth and strengthen antioxidant defense in tumor cells. All of these metabolic changes meet different demands of RAS-driven cancers, making them distinct from normal cells. Indeed, some achievements have been made to inhibit tumor growth through targeting specific metabolism rewiring in preclinical models. Although there is still a long way to elucidate the landscape of altered metabolism, we believe that specific metabolic enzymes or pathways could be therapeutically targeted for selective inhibition of RAS-driven cancers.

Rice Bran Protein Hydrolysates Improve Insulin Resistance and Decrease Pro-inflammatory Cytokine Gene Expression in Rats Fed a High Carbohydrate-High Fat Diet

A high carbohydrate-high fat (HCHF) diet causes insulin resistance (IR) and metabolic syndrome (MS). Rice bran has been demonstrated to have anti-dyslipidemic and anti-atherogenic properties in an obese mouse model. In the present study, we investigated the beneficial effects of rice bran protein hydrolysates (RBP) in HCHF-induced MS rats. After 12 weeks on this diet, the HCHF-fed group was divided into four subgroups, which were orally administered RBP 100 or 500 mg/kg, pioglitazone 10 mg/kg, or tap water for a further 6 weeks. Compared with normal diet control group, the MS rats had elevated levels of blood glucose, lipid, insulin, and HOMA-IR. Treatment with RBP significantly alleviated all those changes and restored insulin sensitivity. Additionally, RBP treatment increased adiponectin and suppressed leptin levels. Expression of Ppar-γ mRNA in adipose tissues was significantly increased whereas expression of lipogenic genes Srebf1 and Fasn was significantly decreased. Levels of mRNA of proinflammatory cytokines, Il-6, Tnf-α, Nos-2 and Mcp-1 were significantly decreased. In conclusion, the present findings support the consumption of RBP as a functional food to improve insulin resistance and to prevent the development of metabolic syndrome.