Knockdown of CD44 inhibits the invasion and metastasis of hepatocellular carcinoma both in vitro and in vivo by reversing epithelial-mesenchymal transition

Emodin is a Potential Drug Targeting CD44-positive Hepatocellular Cancer

BACKGROUND

Liver cancer is one of the most prevalent forms of cancer of the digestive system in our country. The most common subtype of this disease is hepatocellular carcinoma (HCC). Currently, treatment options for HCC patients include surgical resection, liver transplantation, radiofrequency ablation, chemoembolization, and biologic-targeted therapy. However, the efficacy of these treatments is suboptimal, as they are prone to drug resistance, metastasis, spread, and recurrence. These attributes are closely related to cancer stem cells (CSCs). Therefore, the utilization of drugs targeting CSCs may effectively inhibit the development and recurrence of HCC.

METHODS

HepG2 and Huh7 cells were used to analyze the antitumor activity of emodin by quantifying cell growth and metastasis, as well as to study its effect on stemness.

RESULTS

Emodin effectively suppressed the growth and movement of HCC cells. Emodin also significantly inhibited the proliferation of CD44-positive hepatoma cells.

CONCLUSION

Emodin shows promise as a potential therapeutic agent for HCC by targeting CD44-- positive hepatoma cells.

Identification of a gene set that maintains tumorigenicity of the hepatocellular carcinoma cell line Li-7

The identification and development of therapeutic targets in cancer stem cells that lead to tumor development, recurrence, metastasis, and drug resistance is an important goal in cancer research. The hepatocellular carcinoma cell line Li-7 contains functionally different types of cells. Cells with tumor-forming activity are enriched in cancer stem cell-like CD13+CD166- cells and this cell population gradually decreases during culture in conventional culture medium (RPMI1640 containing 10% fetal bovine serum). When Li-7 cells are cultured in mTeSR1, a medium developed for human pluripotent stem cells, CD13+CD166- cells, and their tumorigenicity is maintained. Here, we sought to identify the mechanisms of tumorigenicity in this sub-population. We compared gene expression profiles of CD13+CD166- cells with other cell sub-populations and identified nine overexpressed genes (ENPP2, SCGN, FGFR4, MCOLN3, KCNJ16, SMIM22, SMIM24, SERPINH1, and TMPRSS2) in CD13+CD166- cells. After transfer from mTeSR1 to RPMI1640 containing 10% fetal bovine serum, the expression of these nine genes decreased in Li-7 cells and they lost tumorigenicity. In contrast, when these genes of Li-7 cells were forcibly expressed in cultures using RPMI1640 containing 10% fetal bovine serum, Li-7 cells maintained tumorigenicity. A metabolome analysis using capillary electrophoresis-mass spectrometry showed that two metabolic pathways, "Alanine, aspartate and glutamate metabolism" and "Arginine biosynthesis" were activated in cancer stem-cell-like cells. Our analyses here showed potential therapeutic target genes and metabolites for treatment of cancer stem cells in hepatocellular carcinoma.

Photothermal Attenuation of Cancer Cell Stemness, Chemoresistance, and Migration Using CD44-Targeted MoS2 Nanosheets

Cancer stem-like cells (CSCs) play key roles in chemoresistance, tumor metastasis, and clinical relapse. However, current CSC inhibitors lack specificity, efficacy, and applicability to different cancers. Herein, we introduce a nanomaterial-based approach to photothermally induce the differentiation of CSCs, termed "photothermal differentiation", leading to the attenuation of cancer cell stemness, chemoresistance, and metastasis. MoS2 nanosheets and a moderate photothermal treatment were applied to target a CSC surface receptor (i.e., CD44) and modulate its downstream signaling pathway. This treatment forces the more stem-like cancer cells to lose the mesenchymal phenotype and adopt an epithelial, less stem-like state, which shows attenuated self-renewal capacity, more response to anticancer drugs, and less invasiveness. This approach could be applicable to various cancers due to the broad availability of the CD44 biomarker. The concept of using photothermal nanomaterials to regulate specific cellular activities driving the differentiation of CSCs offers a new avenue for treating refractory cancers.

Fueling HCC Dynamics: Interplay Between Tumor Microenvironment and Tumor Initiating Cells

Liver cancer (hepatocellular carcinoma) is a common cancer worldwide. It is an aggressive cancer, with high rates of tumor relapse and metastasis, high chemoresistance, and poor prognosis. Liver tumor-initiating cells (LTICs) are a distinctive subset of liver cancer cells with self-renewal and differentiation capacities that contribute to intratumoral heterogeneity, tumor recurrence, metastasis, and chemo-drug resistance. LTICs, marked by different TIC markers, have high plasticity and use diverse signaling pathways to promote tumorigenesis and tumor progression. LTICs are nurtured in the tumor microenvironment (TME), where noncellular and cellular components participate to build an immunosuppressive and tumor-promoting niche. As a result, the TME has emerged as a promising anticancer therapeutic target, as exemplified by some successful applications of tumor immunotherapy. In this review, we discuss the plasticity of LTICs in terms of cellular differentiation, epithelial-mesenchymal transition, and cellular metabolism. We also discuss the various components of the TME, including its noncellular and cellular components. Thereafter, we discuss the mutual interactions between TME and LTICs, including recently reported molecular mechanisms. Lastly, we summarize and describe new ideas concerning novel approaches and strategies for liver cancer therapy.

Cellular and Molecular Biology of Cancer Stem Cells of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death globally. The cancer stem cells (CSCs) of HCC are responsible for tumor growth, invasion, metastasis, recurrence, chemoresistance, target therapy resistance and radioresistance. The reported main surface markers used to identify liver CSCs include epithelial cell adhesion/activating molecule (EpCAM), cluster differentiation 90 (CD90), CD44 and CD133. The main molecular signaling pathways include the Wnt/β-catenin, transforming growth factors-β (TGF-β), sonic hedgehog (SHH), PI3K/Akt/mTOR and Notch. Patients with EpCAM-positive alpha-fetoprotein (AFP)-positive HCC are usually young but have advanced tumor-node-metastasis (TNM) stages. CD90-positive HCCs are usually poorly differentiated with worse prognosis. Those with CD44-positive HCC cells develop early metastases. Those with CD133 expression have a higher recurrence rate and a shorter overall survival. The Wnt/β-catenin signaling pathway triggers angiogenesis, tumor infiltration and metastasis through the enhancement of angiogenic factors. All CD133+ liver CSCs, CD133+/EpCAM+ liver CSCs and CD44+ liver CSCs contribute to sorafenib resistance. SHH signaling could protect HCC cells against ionizing radiation in an autocrine manner. Reducing the CSC population of HCC is crucial for the improvement of the therapy of advanced HCC. However, targeting CSCs of HCC is still challenging.

Proteolysis of CD44 at the cell surface controls a downstream protease network

The cell surface receptor cluster of differentiation 44 (CD44) is the main hyaluronan receptor of the human body. At the cell surface, it can be proteolytically processed by different proteases and was shown to interact with different matrix metalloproteinases. Upon proteolytic processing of CD44 and generation of a C-terminal fragment (CTF), an intracellular domain (ICD) is released after intramembranous cleavage by the γ-secretase complex. This intracellular domain then translocates to the nucleus and induces transcriptional activation of target genes. In the past CD44 was identified as a risk gene for different tumor entities and a switch in CD44 isoform expression towards isoform CD44s associates with epithelial to mesenchymal transition (EMT) and cancer cell invasion. Here, we introduce meprin β as a new sheddase of CD44 and use a CRISPR/Cas9 approach to deplete CD44 and its sheddases ADAM10 and MMP14 in HeLa cells. We here identify a regulatory loop at the transcriptional level between ADAM10, CD44, MMP14 and MMP2. We show that this interplay is not only present in our cell model, but also across different human tissues as deduced from GTEx (Gene Tissue Expression) data. Furthermore, we identify a close relation between CD44 and MMP14 that is also reflected in functional assays for cell proliferation, spheroid formation, migration and adhesion.

Targeting Effect of Betulinic Acid Liposome Modified by Hyaluronic Acid on Hepatoma Cells In Vitro

Betulinic acid (BA) is a natural pentacyclic triterpenoid with broad-spectrum anticancer activity, which has great development potential as an anti-cancer drug. In this study, a novel hyaluronic acid (HA)-modified BA liposome (BA-L) was developed for use in targeted liver cancer therapy. The size, polymer dispersity index (PDI), zeta potential, and entrapment efficiency were measured. Cell viability, cell migration and clonogenicity, cellular uptake, immunohistochemistry of CD44, and protein expression of ROCK1/IP3/RAS were also investigated. BA, BA-L, and HA-BA-L had no inhibitory effect on the activity of LO2 normal hepatocytes, but they inhibited the proliferation of HepG2 and SMMC-7721 cells in a dose- and time-dependent manner, with HA-BA-L exhibiting the most prominent inhibitory effect. Compared with the BA-L group, the expression of CD44 in HepG2 cells in the HA-BA-L group was decreased. The results of WB showed that BA, BA-L, and HA-BA-L downregulated the expression of ROCK1, IP3, and RAS in HepG2 cells, and the expression level in the HA-BA-L group was significantly decreased. The easily prepared HA-BA-L was demonstrated to be an excellent CD44-mediated intracellular delivery system capable of targeting effects. Further mechanistic research revealed that the inhibition of HA-BA-L on HepG2 cells may be mediated by blocking the ROCK1/IP3/RAS signaling pathways.

CD44 Promotes Breast Cancer Metastasis through AKT-Mediated Downregulation of Nuclear FOXA2

The primary cause of breast cancer mortality is the metastatic invasion of cancerous stem cells (CSC). Cluster of differentiation 44 (CD44) is a well-known CSC marker in various cancers, as well as a key role player in metastasis and relapse of breast cancer. CD44 is a cell-membrane embedded protein, and it interacts with different proteins to regulate cancer cell behavior. Transcription factor forkhead box protein A2 (FOXA2) acts as an important regulator in multiple cancers, including breast cancer. However, the biological significance of CD44-FOXA2 association in breast cancer metastasis remains unclear. Herein, we observed that CD44 expression was higher in metastatic lymph nodes compared to primary tumors using a flow cytometric analysis. CD44 overexpression in breast cancer cell lines significantly promoted cell migration and invasion abilities, whereas the opposite effects occurred upon the knockdown of CD44. The stem cell array analysis revealed that FOXA2 expression was upregulated in CD44 knockdown cells. However, the knockdown of FOXA2 in CD44 knockdown cells reversed the effects on cell migration and invasion. Furthermore, we found that CD44 mediated FOXA2 localization in breast cancer cells through the AKT pathway. Moreover, the immunofluorescence assay demonstrated that AKT inhibitor wortmannin and AKT activator SC79 treatment in breast cancer cells impacted FOXA2 localization. Collectively, this study highlights that CD44 promotes breast cancer metastasis by downregulating nuclear FOXA2.

Hemimycale Arabica Induced Non-Cytotoxic Anti-Migratory Activity in Hepatocellular Carcinoma In Vitro

OBJECTIVE

In this work, we represented new non-cytotoxic treatments to avoid serious side effects of current used cytotoxic anticancer drugs. These treatments can compensate in finding convenient treatment for each individual case using a single agent from marine sponge Hemimycale arabica.

METHODS

The ethanol extract was partitioned by cold sequential liquid-liquid extraction to afford petroleum ether, diethyl ether, dichloromethane and ethyl acetate fractions. Chemical composition of H. arabica was performed by gas-liquid chromatography and gas chromatography-mass spectroscopy. Anticancer activity was evaluated by means of cytotoxicity, apoptosis induction, tumor cell migration inhibition and expression analysis of proliferation and migration-related genes.

RESULTS

Our results revealed that all treatments were non-cytotoxic except for dichloromethane fraction which exhibited moderate cytotoxic activity. Caspase-independent apoptosis was induced by total ethanol and dichloromethane fractions while ethyl acetate fraction induces caspase-dependent apoptosis. All treatments inhibited matrix metalloproteinase-independent migration. Petroleum ether and dichloromethane inhibited migration through the down-regulation of FGF and it could be used as anticancer therapy for VEGF-resistance patients. While ethanol inhibited tumor cell migration through down-regulation of all tested genes expression. Ether and ethyl acetate fractions exerted anti-migratory activity without affecting the tested genes. All resuls were statistically significant at p˂0.05.

CONCLUSION

Total ethanol extract is a promising non-cytotoxic anticancer agent because of its powerful apoptosis induction and capability to block tumor cell migration. Petroleum ether and ether fractions area weak non-cytotoxic anti-migratory agents. Dichloromethane could be a moderate cytotoxic anti-migratory agent induced caspase-independent apoptosis. It could be used in anticancer therapy for VEGF-resistance patients through downregulation of FGF. Ethyl acetate fraction considered a non-cytotoxic agent exerting moderate anti-migratory activity. The new sponge-derived treatments can solve different resistance problems to find a convenient treatment for each individual case using a single agent.

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.

Hyaluronated and PEGylated Liposomes as a Potential Drug-Delivery Strategy to Specifically Target Liver Cancer and Inflammatory Cells

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and is characterized by poor clinical outcomes, with the majority of patients not being eligible for curative therapy and treatments only being applicable for early-stage tumors. CD44 is a receptor for hyaluronic acid (HA) and is involved in HCC progression. The aim of this work is to propose HA- and PEGylated-liposomes as promising approaches for the treatment of HCC. It has been found, in this work, that CD44 transcripts are up-regulated in HCC patients, as well as in a murine model of NAFLD/NASH-related hepatocarcinogenesis. Cell culture experiments indicate that HA-liposomes are more rapidly and significantly internalized by Huh7 cells that over-express CD44, compared with HepG2 cells that express low levels of the receptor, in which the uptake seems due to endocytic events. By contrast, human and murine macrophage cell lines (THP-1, RAW264.7) show improved and rapid uptake of PEG-modified liposomes without the involvement of the CD44. Moreover, the internalization of PEG-modified liposomes seems to induce polarization of THP1 towards the M1 phenotype. In conclusion, data reported in this study indicate that this strategy can be proposed as an alternative for drug delivery and one that dually and specifically targets liver cancer cells and infiltrating tumor macrophages in order to counteract two crucial aspect of HCC progression.

Knockdown of CXCL5 inhibits the invasion, metastasis and stemness of bladder cancer lung metastatic cells by downregulating CD44

In our previous studies, we found that T24 lung metastatic cancer cells showed high invasion and metastasis abilities and cancer stem cell characteristics compared with T24 primary cancer cells. By screening for the expression of CXC chemokines in both cell lines, we found that CXCL5 is highly expressed in T24-L cells. The aim of this study is to shed light on the relationship of CXCL5 with epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). RNAi technology was used to decrease CXCL5 expression in the T24-L cell line, and the EMT and CSCs of the shCXCL5 group and the control group were compared. The CXCR2 inhibitor SB225002 was used to inhibit the receptor of CXCL5 to determine the effect of the CXCL5/CXCR2 axis. The knockdown of CXCL5 expression in T24-L cells reduced their EMT and CSC characteristics. RT-PCR and Western blot analyses revealed the downregulation of N-cadherin, Vimentin and CD44. In addition, when CD44 expression was knocked down, the EMT ability of the cells was also inhibited. This phenomenon was most pronounced when both CXCL5 and CD44 were knocked down. CXCL5 and CD44 can affect the EMT and stem cell capacity of T24-L cells through some interaction.

Integrative analysis of long non-coding RNAs and mRNAs associated with tumorigenesis of salivary gland pleomorphic adenoma

OBJECTIVE

The current study investigated long non-coding RNA (lncRNA) and mRNA profiles of the human salivary gland pleomorphic adenoma (SGPA).

DESIGN

Microarray analysis was used to study the expression of lncRNAs and mRNAs and the differentially expressed lncRNAs in human SGPA (all from parotid gland) were identified. The differentially expressed lncRNAs were subjected to qRT-PCR to verify and quantify their expression and a lncRNA-mRNA co-expression network was constructed. The lncRNAs correlated to pleomorphic adenoma gene 1 (PLAG1), a known key transcription factor, were identified and analyzed.

RESULTS

In the present study, 17,382 lncRNAs and 8132 mRNAs were found to be significantly differentially expressed in SGPA (fold change > 2, P < 0.05). The expression of three lncRNAs (NR_110874, NR_110875 and T087085) was significantly altered in SGPA compared to the corresponding healthy tissues, and it was confirmed using the lncRNA-mRNA co-expression network analysis that several lncRNAs interact with 5 key regulators (PLAG1, CTNNB1, CCND1, IGF2, and TP53). Furthermore, T042819 was significantly upregulated in SGPA, which may upregulate PLAG1 by sponging has-miR195-5p.

CONCLUSION

These data suggested that the differently expressed lncRNAs may contribute to the tumorigenesis of SGPA, and analyzing the differences in the lncRNA expression profiles may provide novel insights into the pathogenesis of SGPA.

CD44 Promotes Lung Cancer Cell Metastasis through ERK-ZEB1 Signaling

Lung cancer is a malignancy with high mortality worldwide, and metastasis occurs at a high frequency even when cancer spread is not detectable at primary operation. Cancer stemness plays an important role in malignant cancer behavior, treatment resistance, and cancer metastasis. Therefore, understanding the molecular pathogenesis behind cancer-stemness-mediated metastasis and developing effective approaches to prevent metastasis are key issues for improving cancer treatment. In this study, we investigated the role of CD44 stemness marker in lung cancer using in vitro and clinical studies. Immunohistochemical staining of lung cancer tissue specimens revealed that primary tumors with higher CD44 expression showed increased metastasis to regional lymph nodes. Flow cytometry analysis suggested that CD44 positive cells were enriched in the metastatic lymph nodes compared to the primary tumors. CD44 overexpression significantly increased migration and invasion abilities of lung cancer cells through CD44-induced ERK phosphorylation, ZEB1 upregulation, and Claudin-1 downregulation. Furthermore, ERK inhibition suppressed the migration and invasion abilities of CD44-overexpressing lung cancer cells. In summary, our in vitro and clinical results indicate that CD44 may be a potential prognostic and therapeutic marker for lung cancer patients.

Immunotherapy against programmed death-1/programmed death ligand 1 in hepatocellular carcinoma: Importance of molecular variations, cellular heterogeneity, and cancer stem cells

Hepatocellular carcinoma (HCC) is a heterogeneous malignancy related to diverse etiological factors. Different oncogenic mechanisms and genetic variations lead to multiple HCC molecular classifications. Recently, an immune-based strategy using immune checkpoint inhibitors (ICIs) was presented in HCC therapy, especially with ICIs against the programmed death-1 (PD-1) and its ligand PD-L1. However, despite the success of anti-PD-1/PD-L1 in other cancers, a substantial proportion of HCC patients fail to respond. In this review, we gather current information on biomarkers of anti-PD-1/PD-L1 treatment and the contribution of HCC heterogeneity and hepatic cancer stem cells (CSCs). Genetic variations of PD-1 and PD-L1 are associated with chronic liver disease and progression to cancer. PD-L1 expression in tumoral tissues is differentially expressed in CSCs, particularly in those with a close association with the tumor microenvironment. This information will be beneficial for the selection of patients and the management of the ICIs against PD-1/PD-L1.

Interplay of autophagy and cancer stem cells in hepatocellular carcinoma

Liver cancer is the sixth most common cancer and the fourth leading cause of cancer deaths in the world. The most common type of liver cancers is hepatocellular carcinoma (HCC). Autophagy is the cellular digestion of harmful components by sequestering the waste products into autophagosomes followed by lysosomal degradation for the maintenance of cellular homeostasis. The impairment of autophagy is highly associated with the development and progression of HCC although autophagy may be involved in tumour-suppressing cellular events. In regards to its protecting role, autophagy also shelters the cells from anoikis- a programmed cell death in anchorage-dependent cells detached from the surrounding extracellular matrix which facilitates metastasis in HCC. Liver cancer stem cells (LCSCs) have the ability for self-renewal and differentiation and are associated with the development and progression of HCC by regulating stemness, resistance and angiogenesis. Interestingly, autophagy is also known to regulate normal stem cells by promoting cellular survival and differentiation and maintaining cellular homeostasis. In this review, we discuss the basal autophagic mechanisms and double-faceted roles of autophagy as both tumour suppressor and tumour promoter in HCC, as well as its association with and contribution to self-renewal and differentiation of LCSCs.

Cancer and stem cells

Being the second leading cause of death globally, cancer has been a long-standing and rapidly evolving focus of biomedical research and practice in the world. A tremendous effort has been made to understand the origin of cancer cells, the formation of cancerous tissues, and the mechanism by which they spread and relapse, but the disease still remains mysterious. Here, we made an attempt to scrutinize evidences that indicate the role of stem cells in tumorigenesis and metastasis, and cancer relapse. We also looked into the influence of cancers on stem cells, which in turn represent a major constituent of tumor microenvironment. Based on current understandings of the properties of (cancer) stem cells and their relation to cancers, we can foresee that novel therapeutic approaches would become the next wave of cancer treatment.

Targeted Nanoparticles for Co-delivery of 5-FU and Nitroxoline, a Cathepsin B Inhibitor, in HepG2 Cells of Hepatocellular Carcinoma

BACKGROUND

The first choice of treatment in Hepatocellular Carcinoma (HCC) is 5-fluorouracil (5-FU). Nitroxoline (NIT), a potent inhibitor of Cathepsin B, impairs tumor progression by decreased extracellular matrix degradation. The objective of the current project was designed to target nanoparticles for co-delivery of 5-FU and NIT in order to enhance the 5-FU cytotoxic effects and reduce the metastatic properties of HepG2 cells.

METHODS

5-FU and NIT were loaded in chitosan-chondroitin nanoparticles. To target the CD44 receptors of HepG2 cells, Hyaluronic Acid (HA) was conjugated to the chondroitin by adipic acid dihydrazide and the conjugation was confirmed by FTIR and 1HNMR. After physicochemical characterization and optimization of the processing variables, MTT assay was done on HepG2 and NIH3T3 cell lines to determine the cytotoxic properties of HA targeted nanoparticles. Migration of the cells was studied to compare the co-delivery of the drugs with each drug alone.

RESULTS

The optimized nanoparticles showed the particle size of 244.7±16.3nm, PDI of 0.30±0.03, drug entrapment efficiency of 46.3±5.0% for 5-FU and 75.1±0.9% for NIT. The drug release efficiency up to 8 hours was about 37.6±0.9% for 5-FU and 62.9±0.7% for NIT. The co-delivery of 5-FU and NIT in targeted nanoparticles showed significantly more cytotoxicity than the mixture of the two free drugs, non-targeted nanoparticles or each drug alone and reduced the IC50 value of 5-FU from 3.31±0.65μg/ml to 0.17±0.03μg/ml and the migration of HepG2 cells was also reduced to five-fold.

CONCLUSION

Co-delivery of 5-FU and NIT by HA targeted chitosan-chondroitin nanoparticles may be promising in HCC.

siRNA-mediated silencing of CD44 delivered by Jet Pei enhanced Doxorubicin chemo sensitivity and altered miRNA expression in human breast cancer cell line (MDA-MB468)

CD44, as a superficial cellular glycoprotein, is an essential factor in cell-cell and cell-matrix interaction. The CD44 expression level has been substantially up-regulated in breast cancer, and this upregulation facilitates tumor proliferation and angiogenesis. This study aims to evaluate the combination therapy of Jet Pei/CD44-specific-siRNA/doxorubicin in breast cancer MDA-MB468 cell line. The MTT assay, wound healing test, colony formation assay, DAPI staining, and flow cytometry were performed to investigate the tumoral cell viability, migration, clonogenesis, and apoptosis progression. The quantitative real-time PCR (qRT-PCR) was performed to demonstrate the CD44 expression level. Finally, the effect of CD44 silencing on the expression of VEGF, CXCR4, MMP9, and MiR-142-3p was measured. The combination of CD44-specific-siRNA with doxorubicin decreased tumoral metastasis, proliferation, invasion, and migration, and increased apoptosis in MDA-MB468 cells. In conclusions, CD44 can serve as a therapeutic target in breast cancer. Moreover, the combination therapy of CD44-specific-siRNA with doxorubicin can be a promising treatment for patients with breast cancer.

The novel interplay between CD44 standard isoform and the caspase-1/IL1B pathway to induce hepatocellular carcinoma progression

Accumulating data indicate caspase-1 (CASP1), one of the inflammatory caspases, promotes hepatocellular carcinoma (HCC) progression in tumor proliferation, invasion, EMT phenotype and sorafenib resistance. However, the molecular basis of regulating caspase-1 expression and caspase-1/IL1B (interleukin-1β) pathway in HCC remains unclear. Here, we demonstrated the novel interplay between caspase-1/IL1B activation and cluster differentiation 44 standard isoform (CD44s) in HCC. In this study, we observed that CD44s is responsible for caspase-1/IL1B activation both in HCC tissues and five HCC cell lines. In normoxia conditions, CD44s knockdown repressed the activation of caspase-1/IL1B via stimulating AMPK-mediated autophagy. Moreover, our data suggested that p62-induced autophagic degradation of caspase-1 accounted for caspase-1/IL1B inactivation in CD44s deficient cells. Administration of recombinant human IL1B could rescue impaired proliferation, invasion, and EMT phenotype in CD44s deficient HCC cells. Lastly, hypoxia-mediated caspase-1/IL1B overexpression could be abolished by CD44s downregulation through decreasing HIF1A and enhancing autophagic activity. Overall, targeting CD44s is a novel inhibitory mechanism of caspase-1/IL1B expression, both in normoxia and hypoxia conditions.

Effects of Pyrrole-Imidazole Polyamides Targeting Human TGF-β1 on the Malignant Phenotypes of Liver Cancer Cells

Synthetic pyrrole-imidazole (PI) polyamides bind to the minor groove of double-helical DNA with high affinity and specificity, and inhibit the transcription of corresponding genes. In liver cancer, transforming growth factor (TGF)-β expression is correlated with tumor grade, and high-grade liver cancer tissues express epithelial-mesenchymal transition markers. TGF-β1 was reported to be involved in cancer development by transforming precancer cells to cancer stem cells (CSCs). This study aimed to evaluate the effects of TGF-β1-targeting PI polyamide on the growth of liver cancer cells and CSCs and their TGF-β1 expression. We analyzed TGF-β1 expression level after the administration of GB1101, a PI polyamide that targets human TGF-β1 promoter, and examined its effects on cell proliferation, invasiveness, and TGF-β1 mRNA expression level. GB1101 treatment dose-dependently decreased TGF-β1 mRNA levels in HepG2 and HLF cells, and inhibited HepG2 colony formation associated with downregulation of TGF-β1 mRNA. Although GB1101 did not substantially inhibit the proliferation of HepG2 cells compared to untreated control cells, GB1101 significantly suppressed the invasion of HLF cells, which displayed high expression of CD44, a marker for CSCs. Furthermore, GB1101 significantly inhibited HLF cell sphere formation by inhibiting TGF-β1 expression, in addition to suppressing the proliferation of HLE and HLF cells. Taken together, GB1101 reduced TGF-β1 expression in liver cancer cells and suppressed cell invasion; therefore, GB1101 is a novel candidate drug for the treatment of liver cancer.

Cancer Stem Cell Functions in Hepatocellular Carcinoma and Comprehensive Therapeutic Strategies

Hepatocellular carcinoma (HCC) is a significant cause of cancer-related mortality owing to resistance to traditional treatments and tumor recurrence after therapy, which leads to poor therapeutic outcomes. Cancer stem cells (CSC) are a small subset of tumor cells with the capability to influence self-renewal, differentiation, and tumorigenesis. A number of surface markers for liver cancer stem cell (LCSC) subpopulations (EpCAM, CD133, CD44, CD13, CD90, OV-6, CD47, and side populations) in HCC have been identified. LCSCs play critical roles in regulating HCC stemness, self-renewal, tumorigenicity, metastasis, recurrence, and therapeutic resistance via genetic mutations, epigenetic disruption, signaling pathway dysregulation, or alterations microenvironment. Accumulating studies have shown that biomarkers for LCSCs contribute to diagnosis and prognosis prediction of HCC, supporting their utility in clinical management and development of therapeutic strategies. Preclinical and clinical analyses of therapeutic approaches for HCC using small molecule inhibitors, oncolytic measles viruses, and anti-surface marker antibodies have demonstrated selective, efficient, and safe targeting of LCSC populations. The current review focuses on recent reports on the influence of LCSCs on HCC stemness, tumorigenesis, and multiple drug resistance (MDR), along with LCSC-targeted therapeutic strategies for HCC.

Cancer Stem Cells: A Potential Breakthrough in HCC-Targeted Therapy

Cancer stem cells (CSCs) are subpopulations of cells with stem cell characteristics that produce both cancerous and non-tumorigenic cells in tumor tissues. The literature reports that CSCs are closely related to the development of hepatocellular carcinoma (HCC) and promote the malignant features of HCC such as high invasion, drug resistance, easy recurrence, easy metastasis, and poor prognosis. This review discusses the origin, molecular, and biological features, functions, and applications of CSCs in HCC in recent years; the goal is to clarify the importance of CSCs in treatment and explore their potential value in HCC-targeted therapy.

Cell Surface Proteins in Hepatocellular Carcinoma: From Bench to Bedside

Cell surface proteins act as the go-between in carrying the information from the extracellular environment to the intracellular signaling proteins. However, these proteins are often deregulated in neoplastic diseases, including hepatocellular carcinoma. This review discusses several recent studies that have investigated the role of cell surface proteins in the occurrence and progression of HCC, highlighting the possibility to use them as biomarkers of the disease and/or targets for vaccines and therapeutics.

Abnormal CD44 activation of hepatocytes with nonalcoholic fatty accumulation in rat hepatocarcinogenesis

BACKGROUND

Prevalence of nonalcoholic fatty liver disease (NAFLD) is rapidly increasing, and NAFLD has become one of the most common chronic liver diseases worldwide. With abnormal CD44 activation, the severe form of NAFLD can progress to liver cirrhosis and hepatocellular carcinoma (HCC). Thus, the molecular mechanism of CD44 in NAFLD needs to be identified.

AIM

To investigate the relationship between CD44 activation and malignant transformation of rat hepatocytes under nonalcoholic lipid accumulation.

METHODS

Sprague-Dawley rats were fed a high-fat (HF) for 12 wk to entice NAFLD and then with HF plus 2-fluorenylacetamide (0.05%) to induce HCC. Rats were sacrificed every 2 wk, and subsequently divided into the groups based on liver pathological examination (hematoxylin and eosin staining): NAFLD, denaturation, precancerosis, HCC, and control. Liver CD44 mRNA was detected by OneArray. Liver fat as assessed by Oil red O staining or CD44 by immunohistochemical assay was compared with their integral optic density. Serum CD44, alanine aminotransferase, aspartate aminotransferase, triglyceride, total cholesterol, and AFP levels were quantitatively tested.

RESULTS

Elevated CD44 was first reported in hepatocarcinogenesis, with increasing expression from NAFLD to HCC at the protein or mRNA level. The CD44 integral optic density values were significantly different between the control group and the NAFLD (t = 25.433, P < 0.001), denaturation (t = 48.822, P < 0.001), precancerosis (t = 27.751, P < 0.001), and HCC (t = 16.239, P < 0.001) groups, respectively. Hepatic CD44 can be secreted into the blood, and serum CD44 levels in HCC or precancerous rats were significantly higher (P < 0.001) than those in any of the other rats. Positive correlations were found between liver CD44 and CD44 mRNA (r_s = 0.373, P = 0.043) and serum CD44 (r_s = 0.541, P = 0.002) and between liver CD44 mRNA and serum CD44 (r_s = 0.507, P = 0.004). Moreover, significant correlations were found between liver CD44 and liver AFP (r_s = 0.572, P = 0.001), between serum CD44 and serum AFP (r_s = 0.608, P < 0.001), and between CD44 mRNA and AFP mRNA (r_s = 0.370, P = 0.044).

CONCLUSION

The data suggested that increasing CD44 expression is associated with the malignant transformation of hepatocytes in NAFLD.

Micheliolide Inhibits Liver Cancer Cell Growth Via Inducing Apoptosis And Perturbing Actin Cytoskeleton

Purpose

Micheliolide (MCL) is an effector compound of the flower which has been traditionally used to treat inflammation and cancer patients in oriental medicine. MCL has killing effects on several cancer and immune cells by modulating apoptosis, cell cycle, and metabolism. However, the detail of the mechanisms of anti-cancer activity remains to be elucidated and the effect on liver cancer cells is unknown.

Methods

Cell proliferation was determined by CCK8 and clone formation assay. The xenograft liver cancer model formed by injecting Huh7 cells into NUDE mice was used to evaluate the effects of MCL on liver cancer cells in vivo. We evaluated the stemness of cells with spheroid formation assay and flow cytometry assay. The apoptosis was determined by Annexin V assay. F-actin staining and ROS were performed to detect the impairment of the F-actin cytoskeleton and mitochondria.

Results

Here, we first show that MCL inhibits liver cancer cells both in vivo and in vitro by triggering apoptosis which was reduced by anti-oxidant, but not cell-cycle arrest. In addition, MCL induces mitochondrial ROS and caspase-3 activation. Also, we found that the aggregation of mitochondria and the perturbation of F-actin fibers in the MCL-treated liver cancer cells coincidently occurred before the induction of apoptosis and mitochondrial ROS.

Conclusion

These results suggest that F-actin perturbation is involved in impaired mitochondria and apoptosis. Therefore, MCL can be a potent therapeutic reagent for liver cancer, primarily targeting the actin cytoskeleton.

CPAP promotes angiogenesis and metastasis by enhancing STAT3 activity

Centrosomal P4.1-associated protein (CPAP) is overexpressed in hepatocellular carcinoma (HCC) and positively correlated with recurrence and vascular invasion. Here, we found that CPAP plays an important role in HCC malignancies. Functional characterization indicated that CPAP overexpression increases tumor growth, angiogenesis, and metastasis ex vivo and in vivo. In addition, overexpressed CPAP contributes to sorafenib resistance. Mechanical investigation showed that the expression level of CPAP is positively correlated with activated STAT3 in HCC. CPAP acts as a transcriptional coactivator of STAT3 by directly binding with STAT3. Interrupting the interaction between CPAP and STAT3 attenuates STAT3-mediated tumor growth and angiogenesis. Overexpression of CPAP upregulates several STAT3 target genes such as IL-8 and CD44 that are involved in angiogenesis, and CPAP mRNA expression is positively correlated with the levels of both mRNAs in HCC. Knocked-down expression of CPAP impairs IL-6-mediated STAT3 activation, target gene expression, cell migration, and invasion abilities. IL-6/STAT3-mediated angiogenesis is significantly increased by CPAP overexpression and can be blocked by decreased expression of IL-8. Our findings not only shed light on the importance of CPAP in HCC malignancies, but also provide potential therapeutic strategies for inhibiting the angiogenesis pathway and treating metastatic HCC.

c-Met Signaling Is Essential for Mouse Adult Liver Progenitor Cells Expansion After Transforming Growth Factor-β-Induced Epithelial-Mesenchymal Transition and Regulates Cell Phenotypic Switch

Adult hepatic progenitor cells (HPCs)/oval cells are bipotential progenitors that participate in liver repair responses upon chronic injury. Recent findings highlight HPCs plasticity and importance of the HPCs niche signals to determine their fate during the regenerative process, favoring either fibrogenesis or damage resolution. Transforming growth factor-β (TGF-β) and hepatocyte growth factor (HGF) are among the key signals involved in liver regeneration and as component of HPCs niche regulates HPCs biology. Here, we characterize the TGF-β-triggered epithelial-mesenchymal transition (EMT) response in oval cells, its effects on cell fate in vivo, and the regulatory effect of the HGF/c-Met signaling. Our data show that chronic treatment with TGF-β triggers a partial EMT in oval cells based on coexpression of epithelial and mesenchymal markers. The phenotypic and functional profiling indicates that TGF-β-induced EMT is not associated with stemness but rather represents a step forward along hepatic lineage. This phenotypic transition confers advantageous traits to HPCs including survival, migratory/invasive and metabolic benefit, overall enhancing the regenerative potential of oval cells upon transplantation into a carbon tetrachloride-damaged liver. We further uncover a key contribution of the HGF/c-Met pathway to modulate the TGF-β-mediated EMT response. It allows oval cells expansion after EMT by controlling oxidative stress and apoptosis, likely via Twist regulation, and it counterbalances EMT by maintaining epithelial properties. Our work provides evidence that a coordinated and balanced action of TGF-β and HGF are critical for achievement of the optimal regenerative potential of HPCs, opening new therapeutic perspectives. Stem Cells 2019;37:1108-1118.

Hyaluronic acid inhibition by 4-methylumbelliferone reduces the expression of cancer stem cells markers during hepatocarcinogenesis

Hyaluronic acid (HA) is a glycosaminoglycan of extracellular matrix related to cell surface which interacts with various cell types. To understand the role of HA during hepatocarcinogenesis, we assessed the effect of the inhibition of HA deposition and its association with heterogeneous hepatocellular carcinoma (HCC) cells. In this study, we used transgenic mice C57BL/6J-Tg(Alb1HBV)44Bri/J (HBV-TG) and normal C57BL/6 J (WT) for in vivo study, while HCC cells Huh7 and JHH6 as in vitro models. Both models were treated with an HA inhibitor 4-methylumbelliferone (4MU). We observed that 4MU treatments in animal model down-regulated the mRNA expressions of HA-related genes Has3 and Hyal2 only in HBV-TG but not in normal WT. As observed in vivo, in HCC cell lines, the HAS2 mRNA expression was down-regulated in Huh7 while HAS3 in JHH6, both with or without the presence of extrinsic HA. Interestingly, in both models, the expressions of various cancer stem cells (CD44, CD90, CD133, and EpCAM) were also decreased. Further, histological analysis showed that 4MU treatment with dose 25 mg/kg/day reduced fibrosis, inflammation, and steatosis in vivo, in addition to be pro-apoptotic. We concluded that the inhibition of HA reduced the expressions of HA-related genes and stem cells markers in both models, indicating a possible modulation of cells-to-cells and cells-to-matrix interaction.

Intracellular NO-Generator Based on Enzyme Trigger for Localized Tumor-Cytoplasm Rapid Drug Release and Synergetic Cancer Therapy

Nitric oxide (NO) is an important biological messenger implicated in tumor therapy. However, current NO release systems suffer from some disadvantages, such as hydrolysis during blood circulation, poor specificity, and robust irradiation for stimuli. Accordingly, we constructed an intracellular enzyme-triggered NO-generator to achieve tumor cytoplasm-specific disruption and localized rapid drug release. Diethylamine NONOate (DEA/NO) was used as a NO donor and conjugated with hyaluronic acid (HA) to form self-assembly micelle (HA-DNB-DEA/NO), and encapsulate chemotherapeutic agent (doxorubicin (DOX)) into its hydrophobic core (DOX@HA-DNB-DEA/NO). After HA receptor mediated internalization into tumor cells, HA shell would undergo digestion into small conjugated pieces by hyaluronidase. Meanwhile, DOX@HA-DNB-DEA/NO also responded to the intratumoral overexpressed glutathion and glutathione S-transferase π, leading to the intracellular NO production and controlled DOX rapid release. In vitro and in vivo results proved the enzyme-dependent and enhanced targeting delivery profile, and demonstrated that NO and DOX could colocate in specific tumor site, which provided a precondition for exerting their synergistic efficacy. Moreover, expression of p53 protein was upregulated in tumor tissue after treatment, indicating that NO induced cell apoptosis mediated by tumor suppressor gene p53. Overall, this intelligent drug loaded NO-generator might perform as an enhancer to realize better clinical outcomes.

Cancer stem cells in hepatocellular carcinoma: an overview and promising therapeutic strategies

The poor clinical outcome of hepatocellular carcinoma (HCC) patients is ascribed to the resistance of HCC cells to traditional treatments and tumor recurrence after curative therapies. Cancer stem cells (CSCs) have been identified as a small subset of cancer cells which have high capacity for self-renewal, differentiation and tumorigenesis. Recent advances in the field of liver CSCs (LCSCs) have enabled the identification of CSC surface markers and the isolation of CSC subpopulations from HCC cells. Given their central role in cancer initiation, metastasis, recurrence and therapeutic resistance, LCSCs constitute a therapeutic opportunity to achieve cure and prevent relapse of HCC. Thus, it is necessary to develop therapeutic strategies to selectively and efficiently target LCSCs. Small molecular inhibitors targeting the core stemness signaling pathways have been actively pursued and evaluated in preclinical and clinical studies. Other alternative therapeutic strategies include targeting LCSC surface markers, interrupting the CSC microenvironment, and altering the epigenetic state. In this review, we summarize the properties of CSCs in HCC and discuss novel therapeutic strategies that can be used to target LCSCs.

Conjugated Bile Acids Promote Invasive Growth of Esophageal Adenocarcinoma Cells and Cancer Stem Cell Expansion via Sphingosine 1-Phosphate Receptor 2-Mediated Yes-Associated Protein Activation

Esophageal adenocarcinoma (EAC) is the sixth leading cause of cancer deaths worldwide and has been dramatically increasing in incidence over the past decade. Gastroesophageal reflux and Barrett esophagus are well-established risk factors for disease progression. Conjugated bile acids (CBAs), including taurocholate (TCA), represent the major bile acids in the gastroesophageal refluxate of advanced Barrett esophagus and EAC patients. Our previous studies suggested that CBA-induced activation of sphingosine 1-phosphate receptor 2 (S1PR2) plays a critical role in promoting cholangiocarcinoma cell invasive growth. However, the role of CBAs in EAC development and underlying mechanisms remains elusive. In the current study, we identified that the expression level of S1PR2 is correlated to invasiveness of EAC cells. TCA significantly promoted cell proliferation, migration, invasion, transformation, and cancer stem cell expansion in highly invasive EAC cells (OE-33 cells), but had less effect on the lower invasive EAC cells (OE-19 cells). Pharmacologic inhibition of S1PR2 with specific antagonist JTE-013 or knockdown of S1PR2 expression significantly reduced TCA-induced invasive growth of OE-33 cells, whereas overexpression of S1PR2 sensitized OE-19 cells to TCA-induced invasive growth. Furthermore, TCA-induced activation of S1PR2 was closely associated with YAP and β-catenin signaling pathways. In conclusion, CBA-induced activation of the S1PR2 signaling pathway is critically involved in invasive growth of EAC cells and represents a novel therapeutic target for EAC.

Quantitative assessment of CD44 genetic variants and cancer susceptibility in Asians: a meta-analysis

CD44 is a well-established cancer stem cell marker playing a crucial role in tumor metastasis, recurrence and chemo-resistance. Genetic variants of CD44 have been shown to be associated with susceptibility to various cancers; however, the results are confounding. Hence, we performed a meta-analysis to clarify these associations more accurately. Overall, rs13347 (T vs. C: OR=1.30, p=<0.004, p_corr=0.032; CT vs. CC: OR=1.29, p=0.015, p_corr=0.047; TT vs. CC: OR=1.77, p=<0.000, p_corr=0.018; CT+TT vs. CC: OR=1.34, p=<0.009, p_corr=0.041) and rs187115 (GG vs. AA: OR=2.34, p=<0.000, p_corr=0.025; AG vs. AA: OR=1.59, p=<0.000, p_corr=0.038; G vs. A allele OR=1.56, p=0.000, p_corr=0.05; AG+GG vs. AA: OR=1.63, p=<0.000, p_corr=0.013) polymorphisms were found to significantly increase the cancer risk in Asians. On the other hand, rs11821102 was found to confer low risk (A vs. G: OR=0.87, p=<0.027, p_corr=0.04; AG vs. GG: OR=0.85, p=<0.017, p_corr=0.01; AG+AA vs. GG: OR=0.86, p=<0.020, p_corr=0.02). Based on our analysis, we suggest significant role of CD44 variants (rs13347, rs187115 and rs11821102) in modulating individual's cancer susceptibility in Asians. Therefore, these variants may be used as predictive genetic biomarkers for cancer predisposition in Asian populations. However, more comprehensive studies involving other cancers and/or populations, haplotypes, gene-gene and gene-environment interactions are necessary to delineate the role of these variants in conferring cancer risk.

Galunisertib suppresses the staminal phenotype in hepatocellular carcinoma by modulating CD44 expression

Cancer stem cells (CSCs) niche in the tumor microenvironment is responsible for cancer recurrence and therapy failure. To better understand its molecular and biological involvement in hepatocellular carcinoma (HCC) progression, one can design more effective therapies and tailored then to individual patients. While sorafenib is currently the only approved drug for first-line treatment of advanced stage HCC, its role in modulating the CSC niche is estimated to be small. By contrast, transforming growth factor (TGF)-β pathway seems to influence the CSC and thus may impact hallmarks of HCC, such as liver fibrosis, cirrhosis, and tumor progression. Therefore, blocking this pathway may offer an appealing and druggable target. In our study, we have used galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-β receptor I (TGFβI/ALK5) activation, currently under clinical investigation in HCC patients. Because the drug resistance is mainly mediated by CSCs, we tested the effects of galunisertib on stemness phenotype in HCC cells to determine whether TGF-β signaling modulates CSC niche and drug resistance. Galunisertib modulated the expression of stemness-related genes only in the invasive (HLE and HLF) HCC cells inducing a decreased expression of CD44 and THY1. Furthermore, galunisertib also reduced the stemness-related functions of invasive HCC cells decreasing the formation of colonies, liver spheroids and invasive growth ability. Interestingly, CD44 loss of function mimicked the galunisertib effects on HCC stemness-related functions. Galunisertib treatment also reduced the expression of stemness-related genes in ex vivo human HCC specimens. Our observations are the first evidence that galunisertib effectiveness overcomes stemness-derived aggressiveness via decreased expression CD44 and THY1.

Virtual screening-driven repositioning of etoposide as CD44 antagonist in breast cancer cells

CD44 is a receptor for hyaluronan (HA) that promotes epithelial-to-mesenchymal transition (EMT), induces cancer stem cell (CSC) expansion, and favors metastasis. Thus, CD44 is a target for the development of antineoplastic agents. In order to repurpose drugs as CD44 antagonists, we performed consensus-docking studies using the HA-binding domain of CD44 and 11,421 molecules. Drugs that performed best in docking were examined in molecular dynamics simulations, identifying etoposide as a potential CD44 antagonist. Ligand competition and cell adhesion assays in MDA-MB-231 cells demonstrated that etoposide decreased cell binding to HA as effectively as a blocking antibody. Etoposide-treated MDA-MB-231 cells developed an epithelial morphology; increased their expression of E-cadherin; and reduced their levels of EMT-associated genes and cell migration. By gene expression analysis, etoposide reverted an EMT signature similarly to CD44 knockdown, whereas other topoisomerase II (TOP2) inhibitors did not. Moreover, etoposide decreased the proportion of CD44⁺/CD24⁻ cells, lowered chemoresistance, and blocked mammosphere formation. Our data indicate that etoposide blocks CD44 activation, impairing key cellular functions that drive malignancy, thus rendering it a candidate for further translational studies and a potential lead compound in the development of new CD44 antagonists.

Role of ADAM17 in invasion and migration of CD133-expressing liver cancer stem cells after irradiation

We investigated the biological role of CD133-expressing liver cancer stem cells (CSCs) enriched after irradiation of Huh7 cells in cell invasion and migration. We also explored whether a disintegrin and metalloproteinase-17 (ADAM17) influences the metastatic potential of CSC-enriched hepatocellular carcinoma (HCC) cells after irradiation. A CD133-expressing Huh7 cell subpopulation showed greater resistance to sublethal irradiation and specifically enhanced cell invasion and migration capabilities. We also demonstrated that the radiation-induced MMP-2 and MMP-9 enzyme activities as well as the secretion of vascular endothelial growth factor were increased more predominantly in Huh7^CD133+ cell subpopulations than Huh7^CD133− cell subpopulations. Furthermore, we showed that silencing ADAM17 significantly inhibited the migration and invasiveness of enriched Huh7^CD133+ cells after irradiation; moreover, Notch signaling was significantly reduced in irradiated CD133-expressing liver CSCs following stable knockdown of the ADAM17 gene. In conclusion, our findings indicate that CD133-expressing liver CSCs have considerable metastatic capabilities after irradiation of HCC cells, and their metastatic capabilities might be maintained by ADAM17. Therefore, suppression of ADAM17 shows promise for improving the efficiency of current radiotherapies and reducing the metastatic potential of liver CSCs during HCC treatment.

Role of ADAM17 in invasion and migration of CD133-expressing liver cancer stem cells after irradiation

We investigated the biological role of CD133-expressing liver cancer stem cells (CSCs) enriched after irradiation of Huh7 cells in cell invasion and migration. We also explored whether a disintegrin and metalloproteinase-17 (ADAM17) influences the metastatic potential of CSC-enriched hepatocellular carcinoma (HCC) cells after irradiation. A CD133-expressing Huh7 cell subpopulation showed greater resistance to sublethal irradiation and specifically enhanced cell invasion and migration capabilities. We also demonstrated that the radiation-induced MMP-2 and MMP-9 enzyme activities as well as the secretion of vascular endothelial growth factor were increased more predominantly in Huh7CD133+ cell subpopulations than Huh7CD133- cell subpopulations. Furthermore, we showed that silencing ADAM17 significantly inhibited the migration and invasiveness of enriched Huh7CD133+ cells after irradiation; moreover, Notch signaling was significantly reduced in irradiated CD133-expressing liver CSCs following stable knockdown of the ADAM17 gene. In conclusion, our findings indicate that CD133-expressing liver CSCs have considerable metastatic capabilities after irradiation of HCC cells, and their metastatic capabilities might be maintained by ADAM17. Therefore, suppression of ADAM17 shows promise for improving the efficiency of current radiotherapies and reducing the metastatic potential of liver CSCs during HCC treatment.

MicroRNA-150 suppresses cell proliferation and metastasis in hepatocellular carcinoma by inhibiting the GAB1-ERK axis

MicroRNA-150 (miR-150) is frequently dysregulated in cancer and is involved in carcinogenesis and cancer progression. In this study, we found that miR-150 was significantly downregulated in hepatocellular carcinoma (HCC) tissues compared to adjacent noncancerous tissues. Low levels of miR-150 were significantly associated with worse clinicopathological characteristics and a poor prognosis for patients with HCC. miR-150 overexpression inhibited cell proliferation, migration and invasion in vitro and tumor growth and metastasis in vivo. Further experiments indicated that Grb2-associated binding protein 1 (GAB1) was a direct target of miR-150 in HCC cells. In addition, GAB1 expression was increased in HCC tissues and inversely correlated with miR-150 levels. Knockdown of GAB1 mimicked the tumor-suppressive effects of miR-150 overexpression on HCC cells, whereas restoration of GAB1 expression partially abolished the inhibitory effects. Moreover, miR-150 overexpression decreased GAB1 expression, subsequently downregulated phospho-ERK1/2 and suppressed epithelial-mesenchymal-transition (EMT). These effects caused by miR-150 overexpression were alleviated by exogenous GAB1 expression. Taken together, this study demonstrates that miR-150 may be useful as a prognostic marker and that the identified miR-150-GAB1-ERK axis is a potential therapeutic target for HCC.

Whether CD44 is an applicable marker for glioma stem cells

Glioblastoma multiforme (GBM) is one of the most malignant and aggressive brain tumors with great amount of hyaluronan (HA) secretion and CD44 overexpression (HA receptor). CD44 has been suggested as a cancer stem cells (CSCs) marker. However, several clinical studies have indicated that CD44low glioma cell exhibit CSCs traits. Additionally, our previous study indicated that more CD44 expression was associated with a better prognosis in GBM patients. To determine whether CD44 is an appropriate marker of glioma stem cells (GSCs), we manipulated CD44 expression using intrinsic (CD44 knockdown, CD44kd) and extrinsic (HA supplement, HA+) methods. Our results show that CD44kd suppressed cell proliferation by retarding cell cycle progression from G0/G1 to S phase. Furthermore, it caused GSCs traits, including lower expression of differentiation marker (glial fibrillary acidic protein, GFAP), a higher level of sphere formation and higher expression of stem cell markers (CD133, nestin and Oct4). The reduction of CD44 expression induced by HA+ was accompanied by an increase in GSCs properties. Interestingly, the presence of HA+ in glioma cells with GSC traits conversely facilitated differentiation. Our data indicated that the CD44 low-expressing cells exhibit more GSCs straits, suggesting that CD44 is not an appropriate marker for GSCs. Furthermore, the preferential expression of CD44 at the invasive rim in rat glioma specimen implies that CD44 may be more important for invasion and migration instead of GSCs marker in glioma.

STAT3 mediates resistance to anoikis and promotes invasiveness of nasopharyngeal cancer cells

Nasopharyngeal carcinoma (NPC), a tumor arising from the epithelial cells of the nasopharynx, is endemic in Southeast Asia and Taiwan. The prognosis of NPC patients with local recurrence and metastasis is poor. Resistance to anoikis is a primary characteristic of tumor cells that metastasize. However, the mechanism through which NPC cells resist anoikis and are able to metastasize has not been fully elucidated. In the present study, the acquisition of anoikis resistance was analyzed in the TW01 and TW06 human NPC cell lines growing under anchorage-independent conditions. A considerable number of TW01 and TW06 cells was found to be resistant to anoikis and exhibited a higher capability of migration and invasion. These anoikis-resistant NPC cells exhibited significantly increased expression of signal transducer and activation of transcription 3 (Stat3) compared with adherent cells. Furthermore, blockade of STAT3 expression by STAT3 inhibitors or STAT3 silencing significant increased anoikis in anoikis-resistant NPC cells. Moreover, silencing STAT3 not only reduced the capacity of NPC cells to resist anoikis, but also reversed their invasive properties. The expression of epithelial‑to-mesenchymal transition‑related proteins and CD44 was also significantly decreased following STAT3 knockdown. The results of the present study established that STAT3 mediates anoikis resistance, with enhanced cell migration and invasion of NPC cells, and that activation of STAT3 may increase metastatic capacity, indicating the crucial role of STAT3 in conferring anoikis resistance and enhanced invasive properties to NPC cells.

T-cell immunoglobulin mucin-3 as a potential inducer of the epithelial-mesenchymal transition in hepatocellular carcinoma

T-cell immunoglobulin mucin (TIM)-3 is an important member of the TIM gene family, which was thought to contribute to the progression of numerous types of cancer, including hepatocellular carcinoma (HCC); however, the mechanism underlying TIM-3 functions in HCC progression has not yet been extensively investigated. The present study aimed to investigate the function of TIM-3 in the metastasis of HCC and to determine whether the alteration of TIM-3 expression levels regulated the epithelial-mesenchymal transition (EMT) occurrence of HCC, using epithelial (E)-cadherin, neuronal (N)-cadherin, matrix metallopeptidase-9 (MMP-9), Twist 1, Slug, Snail, and Smad as EMT biomarkers. The results demonstrated that upregulation of TIM-3 using TIM-3 lentiviral activation particles (5 µl) increased cell migration and invasion, which was decreased in TIM-3 short interfering RNA-infected cells (10 µM, 3 µl) correspondingly. SMMC-7721 HCC cells were used as the control. EMT was aggravated in TIM-3 upregulated SMMC-7721 cells, which was attenuated in the TIM-3 interference group, accompanied by an alteration of E-cadherin, N-cadherin, MMP-9, Twist 1, Slug, Snail and Smad expression levels. The data presented suggests that TIM-3 serves an essential role in the metastasis of HCC, the mechanism of which was associated with EMT occurrence. Interference of TIM-3 is expected to be an effective means to prevent and control EMT, and further the metastasis of HCC.

Downregulation of AZGP1 by Ikaros and histone deacetylase promotes tumor progression through the PTEN/Akt and CD44s pathways in hepatocellular carcinoma

Increasing evidence has shown that zinc-alpha2-glycoprotein (AZGP1) is associated with the progression and prognosis of several tumor types. However, little is known regarding the underlying molecular mechanisms of AZGP1 in hepatocellular carcinoma (HCC). In this study, we report that transcription factor Ikaros bound to the AZGP1 promoter and increased its expression in HCC cells. The downregulation of AZGP1 was associated with histone deacetylation in HCC. In addition, the positive feedback regulation via acetylation of histone H4-mediated transactivation of the Ikaros promoter and the Ikaros-mediated transactivation of the acetylation of histone H4 were crucial for regulating AZGP1 expression in HCC cells. Moreover, low serum AZGP1 level in HCC patients was associated with poor prognosis. The ectopic overexpression of AZGP1 or recombinant AZGP1 protein inhibited HCC cell proliferation, migration and invasion in vitro and in vivo, whereas silencing AZGP1 expression resulted in increased cell proliferation, migration and invasion in vitro. In addition, we found that AZGP1 inhibited cell migration and invasion through the regulation of the PTEN/Akt and CD44s pathways. Collectively, our findings revealed the molecular mechanism of AZGP1 expression in HCC, providing new insights into the mechanisms underlying tumor progression.

The histone demethylase KDM3A, and its downstream target MCAM, promote Ewing Sarcoma cell migration and metastasis

Ewing Sarcoma is the second most common solid pediatric malignant neoplasm of bone and soft tissue. Driven by EWS/Ets, or rarely variant, oncogenic fusions, Ewing Sarcoma is a biologically and clinically aggressive disease with a high propensity for metastasis. However, the mechanisms underpinning Ewing Sarcoma metastasis are currently not well understood. In the present study, we identify and characterize a novel metastasis-promotional pathway in Ewing Sarcoma, involving the histone demethylase KDM3A, previously identified by our laboratory as a new cancer-promoting gene in this disease. Using global gene expression profiling, we show that KDM3A positively regulates genes and pathways implicated in cell migration and metastasis, and demonstrate, using functional assays, that KDM3A promotes migration in vitro and experimental, post-intravasation, metastasis in vivo. We further identify the melanoma cell adhesion molecule (MCAM) as a novel KDM3A target gene in Ewing Sarcoma, and an important effector of KDM3A pro-metastatic action. Specifically, we demonstrate that MCAM depletion, like KDM3A depletion, inhibits cell migration in vitro and experimental metastasis in vivo, and that MCAM partially rescues impaired migration due to KDM3A knock-down. Mechanistically, we show that KDM3A regulates MCAM expression both through a direct mechanism, involving modulation of H3K9 methylation at the MCAM promoter, and an indirect mechanism, via the Ets1 transcription factor. Finally, we identify an association between high MCAM levels in patient tumors and poor survival, in two different Ewing Sarcoma clinical cohorts. Taken together, our studies uncover a new metastasis-promoting pathway in Ewing Sarcoma, with therapeutically targetable components.

Long Noncoding RNA BC032913 as a Novel Therapeutic Target for Colorectal Cancer that Suppresses Metastasis by Upregulating TIMP3

Long noncoding RNAs (lncRNAs) have been shown to play critical roles in the biology of various cancers. However, their expression patterns and biological functions in human colorectal cancer (CRC) remain largely unknown. The aim of this study was to explore lncRNA profiles in CRC and investigate key lncRNAs involved in CRC tumorigenesis and progression. The microarray data of six CRC and matched non-cancerous tissues revealed distinct lncRNA profiles, including 899 upregulated and 1,646 downregulated lncRNAs (p < 0.05, fold change > 2.0). Furthermore, we found that the lncRNA BC032913 was generally underexpressed in 115 CRC samples compared with normal tissues. Reduced BC032913 levels were significantly associated with an advanced tumor, lymph nodes, distant metastasis (TNM) stage and a higher risk of lymph node and distant metastases. BC032913 downregulation indicated poor overall survival in CRC patients. Moreover, BC032913 enhanced the mRNA and protein expression of TIMP3 and inhibited Wnt/β-catenin pathway activity, thus suppressing CRC metastasis in vitro and in vivo. Collectively, the obtained data show that BC032913 plays an inhibitory role in CRC aggression by upregulating TIMP3, followed by inactivation of the Wnt/β-catenin pathway. Our findings indicate that the novel lncRNA BC032913 could serve as a novel prognostic marker and effective therapeutic target for CRC.

Hepatocyte selection medium-enriched hepatocellular carcinoma cells are positive for α-fetoprotein and CD44

Tissues surrounding hepatocellular carcinomas (HCCs) lack glucose. Hepatocyte selection medium (HSM) is deficient in glucose and is supplemented with galactose. HCC cells were cultured in HSM to investigate the stem cell markers α-fetoprotein (AFP) and cluster of differentiation 44 (CD44). HCC cells (HLF and PLC/PRF/5 cells) were cultured in HSM. Viable cell numbers were determined on days 0 and 7 following culture in HSM. RNA was isolated and subjected to reverse transcription-quantitative PCR (RT-qPCR) to analyze the mRNA expression levels of AFP and CD44. Immunostaining was performed to analyze the protein levels of AFP and CD44. The number of viable cells was significantly decreased on day 7 following culture in HSM. The expression levels of AFP and CD44 increased on day 7 as assessed using RT-qPCR. Immunostaining confirmed the results of RT-qPCR analysis. The number of viable HCC cells was decreased in HSM, whereas the expression levels of AFP and CD44 increased. Therefore, HSM is potentially useful for the enrichment of HCC cells with cancer stem cell characteristics.

Expression of Fra-1 in human hepatocellular carcinoma and its prognostic significance

This study aimed to explore the clinical significance and prognostic value of Fra-1 in hepatocellular carcinoma patients after curative resection. Fra-1 expression was investigated using a combination of techniques: immunohistochemistry for 66 samples of hepatocellular carcinoma and quantitative real-time polymerase chain reaction and western blotting assays for 19 matched hepatocellular carcinoma specimens. Fra-1 was present in 38 of 66 (57.6%) tumor tissues, with intense staining in the nuclei. There was also positive staining in 14 of 66 (21.2%) adjacent peritumoral tissues, with weak staining in the cytoplasm. Quantitative real-time polymerase chain reaction and western blotting assays confirmed higher expression of Fra-1 messenger RNA and Fra-1 protein in tumor tissues than adjacent non-tumor tissues for 19 hepatocellular carcinoma samples (p < 0.001). Positive expression of Fra-1 was significantly related to vascular invasion and serum alpha-fetoprotein. Kaplan-Meier survival analysis found that overexpressed Fra-1 was correlated with poor overall survival and disease-free survival. Multivariate analysis identified Fra-1 as an independent prognostic factor. Fra-1 may be involved in the progress of hepatocellular carcinoma and could be a promising molecular candidate in the diagnosis and treatment of hepatocellular carcinoma.