A CD13-targeting peptide integrated protein inhibits human liver cancer growth by killing cancer stem cells and suppressing angiogenesis

Dual inhibition of topoisomerase II and microtubule of podophyllotoxin derivative 5p overcomes cancer multidrug resistance

Compound 5p is a 4β-N-substituted podophyllotoxin derivative, which exhibited potent activity toward drug-resistant K562/A02 cells and decreased MDR-1 mRNA expression. Here, we further investigated its detail mechanism and tested its antitumor activity. 5p exerted catalytic inhibition of topoisomerase IIα, and didn't show the inhibitor of topoisomerase I. 5p exhibited the inhibitory effect on microtubule polymerization. 5p showed potent anti-proliferation against breast cancer, oral squamous carcinoma, and their drug-resistant cell lines, with resistance index of 0.61 and 0.86, respectively. 5p downregulated the expression levels of P-gp in KBV200 cells and BCRP in MCF7/ADR cells in dose-dependent manner. Moreover, 5p induced KB and KBV200 cells arrest at G2/M phase by up-regulating the expression of γ-H2AX, p-Histone H3 and cyclin B1. 5p induced apoptosis and pyroptosis by increased the expression levels of cleaved-PARP, cleaved-caspase3, N-GSDME as well as LDH release in KB and KBV200 cells. In addition, 5p efficiently impaired tumor growth in KB and KBV200 xenograft mice. Conclusively, this work elucidated the dual inhibitor of topoisomerase II and microtubule of 5p and its mechanism of overcoming the multidrug resistance, indicating that 5p exerts the antitumor potentiality.

Potential targets and therapeutics for cancer stem cell-based therapy against drug resistance in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common digestive malignancyin the world, which is frequently diagnosed at late stage with a poor prognosis. For most patients with advanced HCC, the therapeutic options arelimiteddue to cancer occurrence of drug resistance. Hepatic cancer stem cells (CSCs) account for a small subset of tumor cells with the ability of self-renewal and differentiationin HCC. It is widely recognized that the presence of CSCs contributes to primary and acquired drug resistance. Therefore, hepatic CSCs-targeted therapy is considered as a promising strategy to overcome drug resistance and improve therapeutic outcome in HCC. In this article, we review drug resistance in HCC and provide a summary of potential targets for CSCs-based therapy. In addition, the development of CSCs-targeted therapeuticsagainst drug resistance in HCC is summarized in both preclinical and clinical trials. The in-depth understanding of CSCs-related drug resistance in HCC will favor optimization of the current therapeutic strategies and gain encouraging therapeutic outcomes.

Emerging role of interactions between tumor angiogenesis and cancer stem cells

Tumor angiogenesis and cancer stem cells (CSCs) are two major hallmarks of solid tumors. They have long received attention for their critical roles in tumor progression, metastasis and recurrence. Meanwhile, plenty of evidence indicates the close association between CSCs and tumor vasculature. CSCs are proven to promote tumor angiogenesis, and the highly vascularized tumor microenvironment further maintains CSCs growth in return, thereby forming a hard-breaking vicious circle to promote tumor development. Hence, though monotherapy targeting tumor vasculature or CSCs has been extensively studied over the past decades, the poor prognosis has been limiting the clinical application. This review summarizes the crosstalk between tumor vasculature and CSCs with emphasis on small-molecule compounds and the associated biological signaling pathways. We also highlight the importance of linking tumor vessels to CSCs to disrupt the CSCs-angiogenesis vicious circle. More precise treatment regimens targeting tumor vasculature and CSCs are expected to benefit future tumor treatment development.

Integrated metabolomics and network pharmacology revealing the mechanism of arsenic-induced hepatotoxicity in mice

Endemic arsenic (As) poisoning is a severe biogeochemical disease that endangers human health. Epidemiological investigations and animal experiments have confirmed the damaging effects of As on the liver, but there is an urgent need to investigate the underlying mechanisms. This study adopted a metabolomic approach using UHPLC-QE/MS to identify the different metabolites and metabolic mechanisms associated with As-induced hepatotoxicity in mice. A network pharmacology approach was applied to predict the potential target of As-induced hepatotoxicity. The predicted targets of differential metabolites were subjected to a deep matching for elucidating the integration mechanisms. The results demonstrate that the levels of ALT and AST in plasma significantly increased in mice after As exposure. In addition, the liver tissue showed disorganized liver lobules, lax cytoplasm and inflammatory cell infiltration. Metabolomic analysis revealed that As exposure caused disturbance to 40 and 75 potential differential metabolites in plasma and liver, respectively. Further investigation led to discovering five vital metabolic pathways, including phenylalanine, tyrosine, and tryptophan biosynthesis and nicotinate and nicotinamide metabolism pathways. These pathways may responded to As-induced hepatotoxicity primarily through lipid metabolism, apoptosis, and deoxyribonucleic acid damage. The network pharmacology suggested that As could induce hepatotoxicity in mice by acting on targets including Hsp90aa1, Akt2, Egfr, and Tnf, which regulate PI3K Akt, HIF-1, MAPK, and TNF signaling pathways. Finally, the integrated metabolomics and network pharmacology revealed eight key targets associated with As-induced hepatoxicity, namely DNMT1, MAOB, PARP1, MAOA, EPHX2, ANPEP, XDH, and ADA. The results also suggest that nicotinic acid and nicotinamide metabolisms may be involved in As-induced hepatotoxicity. This research identified the metabolites, targets, and mechanisms of As-induced hepatotoxicity, offering meaningful insights and establishing the groundwork for developing antidotes for widespread As poisoning.

Cancer Stem Cells in Hepatocellular Carcinoma: Intrinsic and Extrinsic Molecular Mechanisms in Stemness Regulation

Hepatocellular carcinoma (HCC) remains the most predominant type of liver cancer with an extremely poor prognosis due to its late diagnosis and high recurrence rate. One of the culprits for HCC recurrence and metastasis is the existence of cancer stem cells (CSCs), which are a small subset of cancer cells possessing robust stem cell properties within tumors. CSCs play crucial roles in tumor heterogeneity constitution, tumorigenesis, tumor relapse, metastasis, and resistance to anti-cancer therapies. Elucidation of how these CSCs maintain their stemness features is essential for the development of CSCs-based therapy. In this review, we summarize the present knowledge of intrinsic molecules and signaling pathways involved in hepatic CSCs, especially the CSC surface markers and associated signaling in regulating the stemness characteristics and the heterogeneous subpopulations within the CSC pool. In addition, we recapitulate the effects of crucial extrinsic cellular components in the tumor microenvironment, including stromal cells and immune cells, on the modulation of hepatic CSCs. Finally, we synopsize the currently valuable CSCs-targeted therapy strategies based on intervention in these intrinsic and extrinsic molecular mechanisms, in the hope of shedding light on better clinical management of HCC patients.

IMB5036, a novel pyridazinone compound, inhibits hepatocellular carcinoma growth and metastasis

Background Hepatocellular carcinoma (HCC) is one of the most common cancers with a high mortality rate due to metastasis and relapse. Purpose Here, we reported a small-molecule pyridazinone compound, designated as IMB5036. Its antitumor activity against HCC and underlying mechanism were studied. Methods In vitro cytotoxicity, apoptosis, DNA breaks, and cell motility assays were performed. Protein expression was analyzed by Western blot and microarray analysis. A xenograft tumor model in athymic mice was used to evaluate the antitumor activity. Results IMB5036 displayed potent cytotoxicity against various HCC cell lines. It caused double DNA breakages and induced cell death via apoptosis. It also significantly inhibited the motility of HCC cells. Western blot showed that IMB5036 induced the up-regulation of E-cadherin, while down-regulation of N-cadherin. The gene expression profile analysis and Western blot assay revealed that IMB5036 down-regulated the expression of Tau protein. Analysis of the TCGA dataset revealed that high expression of Tau decreased the survival rate of HCC patients. In vivo experiments proved that IMB5036 significantly inhibited the growth of HCC xenografts in athymic mice. Conclusions These results collectively demonstrate IMB5036 can be a promising therapeutic candidate for patients with HCC.

Mechanism of cancer stemness maintenance in human liver cancer

Primary liver cancer mainly includes the following four types: hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), hepatoblastoma (HB), and combined hepatocellular carcinoma and cholangiocarcinoma (cHCC-CCA). Recent studies have indicated that there are differences in cancer stem cell (CSC) properties among different types of liver cancer. Liver cancer stem cells (LCSCs), also called liver tumor-initiating cells, have been viewed as drivers of tumor initiation and metastasis. Many mechanisms and factors, such as mitophagy, mitochondrial dynamics, epigenetic modifications, the tumor microenvironment, and tumor plasticity, are involved in the regulation of cancer stemness in liver cancer. In this review, we analyze cancer stemness in different liver cancer types. Moreover, we further evaluate the mechanism of cancer stemness maintenance of LCSCs and discuss promising treatments for eradicating LCSCs.

IMB5476, a novel microtubule inhibitor, induces mitotic catastrophe and overcomes multidrug resistance in tumors

IMB5046 is a nitrobenzoate microtubule inhibitor we reported previously. During screening of its structural analogues, we identified a novel compound IMB5476 with increased aqueous solubility. Here, its antitumor activity and the underlying mechanism were investigated. IMB5476 disrupted microtubule networks in cells and arrested cell cycle at G2/M phase. It inhibited purified tubulin polymerization in vitro. Competition assay indicated that it bound to tubulin at the colchicine pocket. Further experiments proved that it induced cell death by mitotic catastrophe and apoptosis. Notably, it was a poor substrate of P-glycoprotein and exhibited potent cytotoxicity against drug-resistant tumor cells. In addition, IMB5476 could inhibit angiogenesis in vitro. IMB5476 also inhibited the growth of drug-resistant KB_V200 xenografts in mice. Conclusively, our data reveal a novel nitrobenzoate microtubule inhibitor with improved aqueous solubility and can overcome multidrug resistance.

Validating Cell Surface Proteases as Drug Targets for Cancer Therapy: What Do We Know, and Where Do We Go?

Cell surface proteases (also known as ectoproteases) are transmembrane and membrane-bound enzymes involved in various physiological and pathological processes. Several members, most notably dipeptidyl peptidase 4 (DPP4/CD26) and its related family member fibroblast activation protein (FAP), aminopeptidase N (APN/CD13), a disintegrin and metalloprotease 17 (ADAM17/TACE), and matrix metalloproteinases (MMPs) MMP2 and MMP9, are often overexpressed in cancers and have been associated with tumour dysfunction. With multifaceted actions, these ectoproteases have been validated as therapeutic targets for cancer. Numerous inhibitors have been developed to target these enzymes, attempting to control their enzymatic activity. Even though clinical trials with these compounds did not show the expected results in most cases, the field of ectoprotease inhibitors is growing. This review summarizes the current knowledge on this subject and highlights the recent development of more effective and selective drugs targeting ectoproteases among which small molecular weight inhibitors, peptide conjugates, prodrugs, or monoclonal antibodies (mAbs) and derivatives. These promising avenues have the potential to deliver novel therapeutic strategies in the treatment of cancers.

Cancer stem cells in hepatocellular carcinoma - from origin to clinical implications

Hepatocellular carcinoma (HCC) is an aggressive disease with a poor clinical outcome. The cancer stem cell (CSC) model states that tumour growth is powered by a subset of tumour stem cells within cancers. This model explains several clinical observations in HCC (as well as in other cancers), including the almost inevitable recurrence of tumours after initial successful chemotherapy and/or radiotherapy, as well as the phenomena of tumour dormancy and treatment resistance. The past two decades have seen a marked increase in research on the identification and characterization of liver CSCs, which has encouraged the design of novel diagnostic and treatment strategies for HCC. These studies revealed novel aspects of liver CSCs, including their heterogeneity and unique immunobiology, which are suggestive of opportunities for new research directions and potential therapies. In this Review, we summarize the present knowledge of liver CSC markers and the regulators of stemness in HCC. We also comprehensively describe developments in the liver CSC field with emphasis on experiments utilizing single-cell transcriptomics to understand liver CSC heterogeneity, lineage-tracing and cell-ablation studies of liver CSCs, and the influence of the CSC niche and tumour microenvironment on liver cancer stemness, including interactions between CSCs and the immune system. We also discuss the potential application of liver CSC-based therapies for treatment of HCC.

IMB5036 inhibits human pancreatic cancer growth primarily through activating necroptosis

IMB5036 is a novel pyridazinone compound with potent cytotoxicity. In this study, we reported its antitumour activity against pancreatic cancer and the underlying mechanism. We found that IMB5036 induced rapid cell swelling and increased membrane permeability in pancreatic cancer cells. IMB5036 increased the ratio of PI+ cells, which could be rescued by necroptosis inhibitor. Furthermore, MLKL inhibitor NSA attenuated the killing effect of IMB5036 on pancreatic cancer cells. IMB5036 stimulated translocation of MLKL and p-MLKL from cytoplasm to cell membrane. IMB5036 upregulated the level of p-RIPK1, p-RIPK3, and p-MLKL. At the same time, IMB5036 also partially activated apoptosis and pyroptosis. IMB5036 inhibited tumour growth in pancreatic xenograft. IMB5036 induced larger necrosis area, increased p-MLKL level, and inhibited Ki67 expression in tumour mass. The study indicates that IMB5036 inhibits human pancreatic cancer growth primarily activating necroptosis.

CDK1 promotes the stemness of lung cancer cells through interacting with Sox2

OBJECTIVES

The promoting roles of cyclin dependent kinase 1 (CDK1) have been revealed in various tumors, however, its effects in the progression of cancer stem cells are still confusing. This work aims to explore the roles of CDK1 in regulating the stemness of lung cancer cells.

METHODS

Online dataset analysis was performed to evaluate the correlation between CDK1 exression and the survival of lung cancer patients. RT-qPCR, western blot, cell viability, sphere-formation analysis and ALDH activity detection were used to investigate the roles of CDK1 on lung cancer cell stemness, viability and chemotherapeutic sensitivity. Immunocoprecipitation (Co-IP) analysis and rescuing experiments were performed to reveal the underlying mechanisms contributing to CDK1-mediated effects on lung cancer cell stemness.

RESULTS

CDK1 mRNA expression was negatively correlated with the overall survival of lung cancer patients and remarkably increased in tumor spheres formed by lung cancer cells compared to the parental cells. Additionally, CDK1 positively regulated the stemness of lung cancer cells. Mechanistically, CDK1 could interact with Sox2 protein, but not other stemness markers (Oct4, Nanog and CD133). Furthermore, CDK1 increased the phosphorylation, cytoplasm-nuclear translocation and transcriptional activity of Sox2 protein in lung cancer cells. Moreover, CDK1 positively regulated the stemness of lung cancer cells in a Sox2-dependent manner. Finally, we revealed that inhibition of CDK1 enhanced the chemotherapeutic sensitivity, which was also rescued by Sox2 overexpression.

CONCLUSIONS

This work reveals a novel CDK1/Sox2 axis responsible for maintaining the stemness of lung cancer cells.

Advances in Liver Cancer Stem Cell Isolation and their Characterization

Over the last decade research on cancer stem cells (CSC) significantly contributed to a better understanding of tumor biology. Given their similarity to normal stem cells, i.e. self-renewal and pluripotency the need arises to develop robust protocols for the isolation and characterization of CSCs. As with other malignancies, hepatic tumors are composed of a heterogeneous population of cells including liver cancer stem cells (LCSC). Yet, a precise understanding of why stem cells become cancerous is still lacking. There is unmet need to develop robust protocols for the successful isolation of LCSCs from human tissue resection material as to assist in the development of molecular targeted therapies. Here we review the research progress made in the isolation and characterization of LCSCs by considering a wide range of cell surface markers and sorting methods, as applied to side populations, microsphere cultures and the gradient centrifugation method. We emphasize the different fluorescence activated cell sorting methods and the possibility to enrich LCSCs by immunomagnetic beads. We review the specificity of functional assays by considering ABCG transporter and ALDH1 enzyme activities and evaluate the in vivo tumorigenicity of LCSCs in highly sensitive bioassays. Finally, we evaluate different LCSC markers in association with viral and non-viral liver disease and explore the potential of novel drug delivery systems targeting CD133, EpCAM, CD13 and CD90 for the development of molecular targeted therapies. Graphical Abstract.

[Targeted drug delivery system for doxorubicin based on a specific peptide and phospholipid nanoparticles]

Doxorubicin is one of the widely known and frequently used chemotherapy drugs for the treatment of various types of cancer, the use of which is difficult due to its high cardiotoxicity. Targeted drug delivery systems are being developed to reduce side effects. One of the promising components as vector molecules (ligands) are NGR-containing peptides that are affinity for the CD13 receptor, which is expressed on the surface of many tumor cells and tumor blood vessels. Previously, a method was developed for preparing a composition of doxorubicin embedded in phospholipid nanoparticles with a targeted fragment in the form of an ultrafine emulsion. The resulting composition was characterized by a small particle size (less than 40 nm) and a high degree of incorporation of doxorubicin (about 93%) into transport nanoparticles. When assessing the penetrating ability and the degree of binding to the surface of fibrosarcoma cells (HT-1080), it was shown that when the composition with the targeted fragment was added to the cells, the level of doxorubicin was almost 2 times higher than that of the liposomal form of doxorubicin, i.e. the drug in the system with the targeted peptide penetrated the cell better. At the same time, on the control line of breast adenocarcinoma cells (MCF-7), which do not express the CD13 receptor on the surface, there was not significant difference in the level of doxorubicin in the cells. The data obtained allow us to draw preliminary conclusions about the prospects of targeted delivery of doxorubicin to tumor cells when using a peptide conjugate containing an NGR motif and the further need for its comprehensive study.

Dual-Target Peptide-Modified Erythrocyte Membrane-Enveloped PLGA Nanoparticles for the Treatment of Glioma

Penetration of the blood–brain barrier (BBB) and the blood–brain tumor barrier (BBTB) remains a significant challenge for the delivery of drugs in the treatment of glioma. Therefore, the development of targeted preparations with the ability to penetrate the BBB and BBTB, and target gliomas, is an important approach if we are to improve the efficacy of glioma treatment. In the current study, an active targeting preparation based on PLGA nanoparticles coated with erythrocyte membranes (RBCNPs) and dual-modified with ^DWSW and NGR peptide ligands (^DWSW/NGR-RBCNPs). Euphorbia factor L1 (EFL1) extracted from euphorbiae semen was used as the model drug. The final nanoparticles were characterized by in vivo and in vitro tests. In vitro results showed that EFL1-loaded ^DWSW/NGR-RBCNPs were taken up by cells and had the ability to penetrate the BBB and BBTB and produce cytotoxic effects. Furthermore, in vivo studies in mice showed that when injected intravenously, these specialized NPs could enter the brain, target tumor tissue, and significantly extend life span. The results showed that dual-targeting EFL1-loaded ^DWSW/NGR-RBCNPs have significant potential as a nanotherapeutic tool for the treatment of brain glioma.

Amarogentin Inhibits Liver Cancer Cell Angiogenesis after Insufficient Radiofrequency Ablation via Affecting Stemness and the p53-Dependent VEGFA/Dll4/Notch1 Pathway

Background

Whether and how amarogentin suppresses the angiogenesis effect in liver cancer cells after insufficient radiofrequency ablation (iRFA) are still poorly studied.

Methods

The number of liver cancer stem cells (LCSCs) and the level of vascular endothelial growth factor A (VEGFA) were assessed in liver cancer tissue after iRFA. Then, CD133-positive cells were detected in iRFA models of HepG2 and Huh7 cell lines treated with amarogentin. Tube formation assays were applied to observe the antiangiogenesis effects of amarogentin. In addition, the angiogenesis-related molecules p53, delta-like ligand 4 (Dll4), and Notch1 were detected in the iRFA cells and mouse models treated with amarogentin.

Results

The mRNA and protein expression levels of CD133 and VEGFA were significantly higher in the residual liver cancer tissue than in the liver cancer tissues treated by hepatectomy. Amarogentin then markedly decreased the percentage of CD133-positive cells in the iRFA model in both HepG2 and Huh7 cell lines. The number of tubules formed by human umbilical vein endothelial cells (HUVECs) was significantly decreased by amarogentin. Inversely, the antiangiogenesis effect of amarogentin was counteracted after p53 silencing in the iRFA cell models.

Conclusion

Amarogentin prevents the malignant transformation of liver cancer after iRFA via affecting stemness and the p53-dependent VEGFA/Dll4/Notch1 pathway to inhibit cancer cell angiogenesis.

In vivo assessment of aminopeptidase N (APN/CD13) specificity of different 68Ga-labelled NGR derivatives using PET/MRI imaging

Aminopeptidase N (APN/CD13) plays an important role in neoangiogenic process in malignancies. Our previous studies have already shown that ⁶⁸Ga-labelled NOTA conjugated asparagine-glycine-arginine peptide (c[KNGRE]-NH₂) specifically bind to APN/CD13 expressing tumors. The aim of this study was to evaluate and compare the APN/CD13 specificity of newly synthesized ⁶⁸Ga-labelled NGR derivatives in vivo by PET/MRI imaging using hepatocellular carcinoma (He/De) and mesoblastic nephroma (Ne/De) tumor models. PET/MRI and ex vivo biodistribution studies were performed 11 ± 1 days after subcutaneous injection of tumor cells and 90 min after intravenous injection of ⁶⁸Ga-NOTA-c(NGR), ⁶⁸Ga-NODAGA-c(NGR), ⁶⁸Ga-NODAGA-c(NGR) (MG1) or ⁶⁸Ga-NODAGA-c(NGR) (MG2). The APN/CD13 selectivity was confirmed by blocking experiments and the APN/CD13 expression was verified by immunohistochemistry. ⁶⁸Ga-labelled c(NGR) derivatives were produced with high specific activity and radiochemical purity. In control animals, low radiotracer accumulation was found in abdominal and thoracic organs. Using tumor-bearing animals we found that the ⁶⁸Ga-NOTA-c(NGR), ⁶⁸Ga-NODAGA-c(NGR), and ⁶⁸Ga-NODAGA-c(NGR) (MG1) derivatives showed higher uptake in He/De and Ne/De tumors, than that of the accumulation of ⁶⁸Ga-NODAGA-c(NGR) (MG2). APN/CD13 is a very promising target in PET imaging, however, the selection of the appropriate ⁶⁸Ga-labelled NGR-based radiopharmaceutical is critical for the precise detection of tumor neo-angiogenesis and for monitoring the efficacy of anticancer therapy.

In Vivo Imaging of Hypoxia and Neoangiogenesis in Experimental Syngeneic Hepatocellular Carcinoma Tumor Model Using Positron Emission Tomography

Introduction

Hypoxia-induced α_νβ₃ integrin and aminopeptidase N (APN/CD13) receptor expression play an important role in tumor neoangiogenesis. APN/CD13-specific ⁶⁸Ga-NOTA-c(NGR), α_νβ₃ integrin-specific ⁶⁸Ga-NODAGA-[c(RGD)]₂, and hypoxia-specific ⁶⁸Ga-DOTA-nitroimidazole enable the in vivo detection of the neoangiogenic process and the hypoxic regions in the tumor mass using positron emission tomography (PET) imaging. The aim of this study was to evaluate whether ⁶⁸Ga-NOTA-c(NGR) and ⁶⁸Ga-DOTA-nitroimidazole allow the in vivo noninvasive detection of the temporal changes of APN/CD13 expression and hypoxia in experimental He/De tumors using positron emission tomography.

Materials and Methods

5 × 10⁶ hepatocellular carcinoma (He/De) cells were used for the induction of a subcutaneous tumor model in Fischer-344 rats. He/De tumor-bearing animals were anaesthetized, and 90 min after intravenous injection of 10.2 ± 1.1 MBq ⁶⁸Ga-NOTA-c(NGR) or ⁶⁸Ga-NODAGA-[c(RGD)]₂ (as angiogenesis tracers) or ⁶⁸Ga-DOTA-nitroimidazole (for hypoxia imaging), whole-body PET/MRI scans were performed.

Results

Hypoxic regions and angiogenic markers (α_vβ₃ integrin and APN/CD13) were determined using ⁶⁸Ga-NOTA-c(NGR), ⁶⁸Ga-DOTA-nitroimidazole, and ⁶⁸Ga-NODAGA-[c(RGD)]₂ in subcutaneously growing He/De tumors in rats. ⁶⁸Ga-NOTA-c(NGR) showed the strong APN/CD13 positivity of He/De tumors in vivo, by which observation was confirmed by western blot analysis. By the qualitative analysis of PET images, heterogenous accumulation was found inside He/De tumors using all radiotracers. Significantly (p ≤ 0.01) higher SUVmean and SUVmax values were found in the radiotracer avid regions of the tumors than those of the nonavid areas using hypoxia and angiogenesis-specific radiopharmaceuticals. Furthermore, a strong correlation was found between the presence of angiogenic markers, the appearance of hypoxic regions, and the tumor volume using noninvasive in vivo PET imaging.

Conclusion

⁶⁸Ga-DOTA-nitroimidazole and ⁶⁸Ga-NOTA-c(NGR) are suitable diagnostic radiotracers for the detection of the temporal changes of hypoxic areas and neoangiogenic molecule (CD13) expression, which vary during tumor growth in a hepatocellular carcinoma model.

The role of LNPEP and ANPEP gene polymorphisms in the pathogenesis of pre-eclampsia

OBJECTIVE

The exact role of renin angiotensin system (RAS) in the pathogenesis of pre-eclampsia has not been established. Gene polymorphisms, however, have been implicated in the pathophysiology. Therefore, the aim of this study was to investigate the association of the Angiotensin IV receptor and aminopeptidase-N in the pathogenesis of pre-eclampsia.

STUDY DESIGN

Stored blood samples of 637 South African women of African ancestry were utilized. The study population was divided into controls (n = 280) and pre-eclampsia (n = 357). Pre-eclampsia was sub-divided into early (n = 187) and late (n = 170) onset subtypes. DNA was extracted from whole blood and genotyped. Odds ratio and 95 % confidence intervals were used to assess the association.

RESULTS

The allele and genotype frequencies of the angiotensin receptor IV and aminopeptidase-N showed no significant difference between the control versus the pre-eclampsia groups. Similarly, allele and genotype distributions of the control group versus the subtypes of pre-eclampsia (early onset and late onset pre-eclampsia) showed no significant differences.

CONCLUSION

The single nucleotide polymorphisms of angiotensin IV receptor (rs18059) and aminopeptidase-N (rs6496603) are not associated with the pathogenesis of pre-eclampsia in women of African ancestry.

DBDx-based drug combinations show highly potent therapeutic efficacy against human pancreatic cancer xenografts in athymic mice

Previous studies have shown that DBDx, a combination consisting of dipyridamole, bestatin and dexamethasone is highly effective against several cancer xenografts in athymic mice. Here the therapeutic effects of DBDx and its combination with gemcitabine or capcitabine against human pancreatic cancer xenografts and the mechanism were studied. In vivo experiments performed in athymic mice showed that the antitumor efficacy of DBDx was much stronger than that of gemcitabine or capecitabine alone. Notably, the combination of DBDx and gemcitabine or capcitabine further enhanced the efficacy. In the case of DBDx (242 mg/kg) plus gemcitabine (100 mg/kg), tumor weight decreased about 97.7%, and tumor sizes were shrinking during the treatment. In the case of DBDx (242 mg/kg) plus capecitabine (718.7 mg/kg), tumor weight decreased about 94.9%. Moreover, DBDx and its combinations obviously prolonged theoverall survival of mice compared with gemcitabine or capcitabine alone. DBDx-based drug combination therapy showed no obvious systematic toxicity. The gene expression profile analysis showed that the genes changed by DBDx were related to immune system and tumor vasculature. The result of protein array showed that the changed proteins in the serum of treated mice were related to immune and inflammation system. These results show that DBDx-based drug combinations, a new strategy which integrates the use of low-cytotoxic drugs and cytotoxic chemotherapeutics, are highly effective regimens against human pancreatic cancer in athymic mice at well tolerated doses. DBDx-based drug combination therapy might provide new options for the treatment of pancreatic cancer.

TRIB3 confers glioma cell stemness via interacting with β-catenin

Here, we aim to explore whether tribbles pseudokinase 3 (TRIB3) enhances glioma cell stemness. TRIB3 was overexpressed in glioma tissues and cell-formed spheres, positively correlated with the size and grade. Additionally, TRIB3 expression displayed a negative correlation with the overall survival rate of glioma patients. Moreover, TRIB3 knockdown reduced the stemness of nonadherent spheres, evident by the decreased sphere-forming ability, stemness master expression, and ALDH1 activity, while TRIB3 overexpression enhanced the stemness of adherent cells, which was rescued by β-catenin knockdown. Mechanistically, TRIB3 activated β-catenin signaling via physically interacting with β-catenin. This study suggests that the TRIB3-β-catenin interaction is responsible for glioma cell stemness.

CD13 as a new tumor target for antibody-drug conjugates: validation with the conjugate MI130110

Background

In the search for novel antibody-drug conjugates (ADCs) with therapeutic potential, it is imperative to identify novel targets to direct the antibody moiety. CD13 seems an attractive ADC target as it shows a differential pattern of expression in a variety of tumors and cell lines and it is internalized upon engagement with a suitable monoclonal antibody. PM050489 is a marine cytotoxic compound tightly binding tubulin and impairing microtubule dynamics which is currently undergoing clinical trials for solid tumors.

Methods

Anti-CD13 monoclonal antibody (mAb) TEA1/8 has been used to prepare a novel ADC, MI130110, by conjugation to the marine compound PM050489. In vitro and in vivo experiments have been carried out to demonstrate the activity and specificity of MI130110.

Results

CD13 is readily internalized upon TEA1/8 mAb binding, and the conjugation with PM050489 did not have any effect on the binding or the internalization of the antibody. MI130110 showed remarkable activity and selectivity in vitro on CD13-expressing tumor cells causing the same effects than those described for PM050489, including cell cycle arrest at G2, mitosis with disarrayed and often multipolar spindles consistent with an arrest at metaphase, and induction of cell death. In contrast, none of these toxic effects were observed in CD13-null cell lines incubated with MI130110. Furthermore, in vivo studies showed that MI130110 exhibited excellent antitumor activity in a CD13-positive fibrosarcoma xenograft murine model, with total remissions in a significant number of the treated animals. Mitotic catastrophes, typical of the payload mechanism of action, were also observed in the tumor cells isolated from mice treated with MI130110. In contrast, MI130110 failed to show any activity in a xenograft mouse model of myeloma cells not expressing CD13, thereby corroborating the selectivity of the ADC to its target and its stability in circulation.

Conclusion

Our results show that MI130110 ADC combines the antitumor potential of the PM050489 payload with the selectivity of the TEA1/8 monoclonal anti-CD13 antibody and confirm the correct intracellular processing of the ADC. These results demonstrate the suitability of CD13 as a novel ADC target and the effectiveness of MI130110 as a promising antitumor therapeutic agent.

TRIB3 promotes lung cancer progression by activating β-catenin signaling

TRIB3 roles in tumor progression have been revealed with similar or opposite results. Here, we found that TRIB3 expression was highly expressed in lung cancer tissues and correlated with tumor grades and metastasis. Functional experiments showed that TRIB3 knockdown (KD) inhibited lung cancer cell migration, invasion, EMT (epithelial-mesenchymal transition) process and stemness. Mechanistic studies demonstrated that TRIB3 physically interacted with β-catenin and increased the recruitment of β-catenin to the promoter region of genes regulated by Wnt. Re-activation of β-catenin attenuated the inhibition of TRIB3 KD on lung cancer progression. These results suggest that TRIB3 interacts with β-catenin and thus activates β-catenin signaling, which is responsible for lung cancer progression, and blocking TRIB3 activity might be developed to treat lung cancer.

Transcription factor Six2 induces a stem cell-like phenotype in renal cell carcinoma cells

Renal cell carcinoma (RCC) accounts for 2-3% of adult malignant tumors, and the incidence of RCC worldwide has increased by about 2% over the past two decades. The homeobox protein Six2 has been shown to promote the stemness of breast cancer cells and play a role in kidney development, but its involvement in RCC progression has not previously been investigated. Here, we found that six2 expression was significantly increased in RCC tissues and negatively correlated with the overall survival of patients with RCC. In addition, six2 expression exhibited a remarkably higher level relative to that in normal renal cells. Functional experiments showed that six2 knockdown attenuated the stemness of RCC cells, which was evident by decreased spheroid formation ability and stemness marker (sox2 and nanog) expression. Mechanistic studies indicated that Six2 directly bound to the enhancer of sox2, promoting sox2 expression and downstream effector expression of nanog. Furthermore, overexpression of sox2 rescued the inhibitory effects of six2 on the stemness of RCC cells. Notably, six2 expression is positively correlated with sox2 and nanog expression in RCC tissues. Collectively, our results point toward a six2/sox2 axis responsible for RCC cell stemness.

The ionophore antibiotic gramicidin A inhibits pancreatic cancer stem cells associated with CD47 down-regulation

Background

Pancreatic cancer stem cells (CSCs), a special population of cells, renew themselves infinitely and resist to various treatment. Gramicidin A (GrA), an ionophore antibiotic derived from microorganism, can form channels across the cell membrane and disrupt cellular ionic homeostasis, leading to cell dysfunction and death. As reported, the ionophore antibiotic salinomycin (Sal) has been proved to kill CSCs effectively. Whether GrA owns the potential as a therapeutic drug for CSCs still remains unknown. This study investigated the effect of GrA on pancreatic CSCs and the mechanism.

Methods

Tumorsphere formation assay was performed to assess pancreatic CSCs self-renewal potential. In vitro hemolysis assay was determined to test the borderline concentration of GrA. CCK-8 assay was used to detect pancreatic cancer cell proliferation capability. Flow cytometry was performed to detect cell apoptosis and mitochondrial membrane potential. Scanning and transmission electron microscopy was used to observe ultrastructural morphological changes on cell membrane surface and mitochondria, respectively. Western blot analysis was used to determine relative protein expression levels. Immunofluorescence staining was performed to observe CD47 re-distribution.

Results

GrA at 0.05 μM caused tumorspheres disintegration and decrease in number of pancreatic cancer BxPC-3 and MIA PaCa-2 cells. GrA and Sal both inhibited cancer cell proliferation. The IC50 values of GrA and Sal for BxPC-3 cells were 0.025 μM and 0.363 μM; while for MIA PaCa-2 cells were 0.032 μM and 0.163 μM, respectively. Compared on equal concentrations, the efficacy of GrA was stronger than that of Sal. GrA at 0.1 μM or lower did not cause hemolysis. GrA induced ultrastructural changes, such as the decrease of microvilli-like protrusions on cell surface membrane and the swelling of mitochondria. GrA down-regulated the expression levels of CD133, CD44, and CD47; in addition, CD47 re-distribution was observed on cell surface. Moreover, GrA showed synergism with gemcitabine in suppressing cancer cell proliferation.

Conclusions

The study found that GrA was highly active against pancreatic CSCs. It indicates that GrA exerts inhibitory effects against pancreatic CSCs associated with CD47 down-regulation, implying that GrA might play a positive role in modulating the interaction between macrophages and tumor cells.

Chemically synthesized LYRM03 could inhibit the metastasis of human breast cancer MDA-MB-231 cells in vitro and in vivo

Aminopeptidase N (APN) belongs to the aminopeptidase family, which is widely distributed throughout the animal and plant kingdoms. APN is thought to be a very important target for cancer therapy as it is linked to cancer progression and metastasis. However, bestatin (Ubenimex) is the only approved drug that targets various aminopeptidases for the treatment of acute myelocytic leukemia and lymphedema. A compound 3-amino-2-hydroxy-4-phenylbutanoylvalylisoleucine (also known as LYRM03), isolated from a Streptomyces strain HCCB10043, exhibited more potent inhibitory activity than bestatin. In this work, we applied a chemical synthesis strategy to generate LYRM03 to overcome the low yields typically achieved from fermentation. Finally, we explored a suite of experiments to determine the bioactivity of LYRM03 and revealed that the metastasis of MDA-MB-231 cells was significantly restrained with LYRM03 treatment or injection both in vitro and in vivo. Because of its anti-metastasis capacity, further structure modifications of LYRM03 will be of interest for its use alone or in combination as a therapy in cancer.

Aminopeptidase N expression in the endometrium could affect endometrial receptivity

Aminopeptidase N (ANPEP) is a membrane-bound zinc-dependent peptidase. Although it is widely believed that ANPEP acts as an important angiogenesis regulatory factor, there are few studies about its function in the female reproductive system. In our previous research, we applied Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) to analyze the influence of different controlled superovulation treatments for Assisted Reproductive Technology, In Vitro Fertilization and Embryo Transfer (IVF-ET)) patients from a global proteomic perspective to search for potential biomarkers associated with endometrium receptivity and embryo implantation. ANPEP is one of the proteins that demonstrated differential expression between different treatment groups and may be closely associated with endometrial receptivity. In this study, we assessed the expression of ANPEP in the endometrium of mice at different ages and found it to be highest in the mature period. We also detected ANPEP expression in the endometrium of IVF-ET patients in the proliferative, preimplantation and implantation stages, and the highest expression level of ANPEP was found in the last group. Human primary endometrial stromal cells were infected with an adenovirus expression vector containing the ANPEP gene and a green fluorescent protein (GFP) fusion protein; the mRNA levels of HOXA-10, LIF, and integrin β3 were found to be increased. Therefore, we conclude that ANPEP could be involved in the regulation of endometrial receptivity.

Lysyl oxidase assists tumor‑initiating cells to enhance angiogenesis in hepatocellular carcinoma

A highly tumorigenic and malignant sub‑population of HCC containing tumor‑initiating cells (TICs) are defined by high self‑renewal and sphere formation ability. Lysyl oxidase (LOX) regulates various factors involved in extracellular matrix (ECM) maintenance, migration and angiogenesis. Certain reports have demonstrated the role of LOX in ECM crosslinking, however, the cancer‑promoting effects of LOX in HCC remain unclear, and whether LOX has a role in the regulation of angiogenesis in HCC TICs has not been elucidated. In the current study, RNA sequencing using next‑generation sequencing technology and bioinformatics analyses revealed that LOX gene expression was significantly upregulated in cell spheres. Sphere cells may form tumors with more vascular enrichment compared with tumors produced from adherent cells, as observed in a mouse xenograft model. LOX expression is correlated with increased vascular endothelial growth factor (VEGF) and platelet‑derived growth factor, as demonstrated by analyses of The Cancer Genome Atlas and Gene Expression Omnibus databases. Conditioned media obtained from LOX‑overexpressing tumor cells stimulated angiogenesis via secreted VEGF and enhanced the tube formation capacity of endothelial cells. Furthermore, these functional behaviors were blocked by the LOX inhibitor β‑aminopropionitrile. These findings provide novel mechanistic insight into the pivotal role of LOX in the regulation of TICs in HCC. Combination of LOX inhibitor with sorafenib is a potentially advantageous strategy for HCC therapy.

RACK1 Promotes Self-Renewal and Chemoresistance of Cancer Stem Cells in Human Hepatocellular Carcinoma through Stabilizing Nanog

Targeting cancer stem cells (CSCs) has been proposed as a new strategy to eradicate malignancies, including hepatocellular carcinoma (HCC). However, the mechanisms by which CSCs sustain their self-renewal and chemoresistance remain elusive. Nanog is a master transcriptional regulator of stemness, especially in CSCs. Its expression is tightly regulated by the ubiquitin-proteasome system in embryonic stem cells (ESCs). Whether the suppression of Nanog ubiquitination contributes to its over-expression in CSCs has not been explored. In addition, the role of receptor for activated C kinase 1 (RACK1), an adaptor protein implicated in HCC growth, in liver CSC-like traits remains to be determined.

Methods: In vitro and in vivo assays were performed to investigate the role of RACK1 in liver CSC-like phenotype and murine ESC function. How RACK1 regulates Nanog expression was explored by immunoblotting and immunohistochemistry. The interaction of RACK1 with Nanog and the consequent effects on Nanog ubiquitination and stemness were then analyzed.

Results: RACK1 promotes self-renewal and chemoresistance of human liver CSCs and maintains murine ESC function. Consistently, RACK1 enhances the expression of Nanog in human HCC cells and murine ESCs. The protein levels of RACK1 in clinical HCC tissues positively correlate with those of Nanog. Further exploration indicates that RACK1 directly binds to Nanog, which prevents its recruitment of E3 ubiquitin ligase FBXW8 and ubiquitin-dependent degradation. The interaction with Nanog is essential for RACK1 to promote stemness.

Conclusions: Our data provide novel insights into the regulation of Nanog protein levels, as well the key role of RACK1 to enhance self-renewal and chemoresistance of CSCs in human HCC.

Intensive fibrosarcoma-binding capability of the reconstituted analog and its antitumor activity

Fibrosarcomas are highly aggressive malignant tumors. It is urgently needed to explore targeted drugs and modalities for more effective therapy. Matrix metalloproteinases (MMPs) play important roles in tumor progression and metastasis, while several MMPs are highly expressed in fibrosarcomas. In addition, tissue inhibitor of metalloproteinase 2 (TIMP2) displays specific interaction with MMPs. Therefore, TIMP2 may play an active role in the development of fibrosarcoma-targeting agents. In the current study, a TIMP2-based recombinant protein LT and its enediyne-integrated analog LTE were prepared; furthermore, the fibrosarcoma-binding intensity and antitumor activity were investigated. As shown, intense and selective binding capability of the protein LT to human fibrosarcoma specimens was confirmed by tissue microarray. Moreover, LTE, the enediyne-integrated analog of LT, exerted highly potent cytotoxicity to fibrosarcoma HT1080 cells, induced apoptosis, and caused G2/M arrest. LTE at 0.1 nM markedly suppressed the migration and invasion of HT1080 cells. LTE at tolerated dose of 0.6 mg/kg inhibited the tumor growth of fibrosarcoma xenograft in athymic mice. The study provides evidence that the TIMP2-based reconstituted analog LTE may be useful as a targeted drug for fibrosarcome therapy.

Nano-delivery system targeting to cancer stem cell cluster of differentiation biomarkers

Cancer stem cells (CSCs) are one of the most important origins of cancer progression and metastasis. CSCs have unique self-renewal properties and diverse cell membrane receptors that induced the resistance to the conventional chemotherapeutic agents. Therefore, the therapeutic removal of CSCs could result in the cancer cure with lack of recurrence and metastasis. In this regard, targeting CSCs in accordance to their specific biomarkers is a talented attitude in cancer therapy. Various CSCs surface biomarkers have been described, which some of them exhibited similarities on different cancer cell types, while the others are cancer specific and have just been reported on one or a few types of cancers. In this review, the importance of CSCs in cancer development and therapeutic response has been stated. Different CSCs cluster of differentiation (CD) biomarkers and their specific function and applications in the treatment of cancers have been discussed, Special attention has been made on targeted nano-delivery systems. In this regard, several examples have been illustrated concerning specific natural and artificial ligands against CSCs CD biomarkers that could be decorated on various nanoparticulated drug delivery systems to enhance therapeutic index of chemotherapeutic agents or anticancer gene therapy. The outlook of CSCs biomarkers discovery and therapeutic/diagnostic applications was discussed.