CD133+ liver cancer stem cells modulate radioresistance in human hepatocellular carcinoma

Cancer stem cell biomarkers and related signalling pathways

Cancer stem cells (CSCs) represent a distinct subset of neoplastic cells characterised by their heightened capacity for tumorigenesis. These cells are implicated in the facilitation of cancer metastasis, recurrence, and resistance to conventional therapeutic interventions. Extensive scientific research has been devoted to the identification of biomarkers and the elucidation of molecular mechanisms in order to improve targeted therapeutic approaches. Accurate identification of cancer stem cells based on biomarkers can provide a theoretical basis for drug combinations of malignant tumours. Targeted biomarker-based therapies also offer a silver lining for patients with advanced malignancies. This review aims comprehensively to consolidate the latest findings on CSCs biomarkers, targeted agents as well as biomarkers associated signalling pathways in well-established cancer types, thereby contributing to improved prognostic outcomes.

Pharmacological agents targeting drug-tolerant persister cells in cancer

Current cancer therapy can be effective, but the development of drug resistant disease is the usual outcome. These drugs can eliminate most of the tumor burden but often fail to eliminate the rare, "Drug Tolerant Persister" (DTP) cell subpopulations in residual tumors, which can be referred to as "Persister" cells. Therefore, novel therapeutic agents specifically targeting or preventing the development of drug-resistant tumors mediated by the remaining persister cells subpopulations are needed. Since approximately ninety percent of cancer-related deaths occur because of the eventual development of drug resistance, identifying, and dissecting the biology of the persister cells is essential for the creation of drugs to target them. While there remains uncertainty surrounding all the markers identifying DTP cells in the literature, this review summarizes the drugs and therapeutic approaches that are available to target the persister cell subpopulations expressing the cellular markers ATP-binding cassette sub-family B member 5 (ABCB5), CD133, CD271, Lysine-specific histone demethylase 5 (KDM5), and aldehyde dehydrogenase (ALDH). Persister cells expressing these markers were selected as the focus of this review because they have been found on cells surviving following drug treatments that promote recurrent drug resistant cancer and are associated with stem cell-like properties, including self-renewal, differentiation, and resistance to therapy. The limitations and obstacles facing the development of agents targeting these DTP cell subpopulations are detailed, with discussion of potential solutions and current research areas needing further exploration.

Can CD133 Be Regarded as a Prognostic Biomarker in Oncology: Pros and Cons

The CD133 cell membrane glycoprotein, also termed prominin-1, is expressed on some of the tumor cells of both solid and blood malignancies. The CD133-positive tumor cells were shown to exhibit higher proliferative activity, greater chemo- and radioresistance, and enhanced tumorigenicity compared to their CD133-negative counterparts. For this reason, CD133 is regarded as a potential prognostic biomarker in oncology. The CD133-positive cells are related to the cancer stem cell subpopulation in many types of cancer. Recent studies demonstrated the involvement of CD133 in the regulation of proliferation, autophagy, and apoptosis in cancer cells. There is also evidence of its participation in the epithelial-mesenchymal transition associated with tumor progression. For a number of malignant tumor types, high CD133 expression is associated with poor prognosis, and the prognostic significance of CD133 has been confirmed in a number of meta-analyses. However, some published papers suggest that CD133 has no prognostic significance or even demonstrate a certain correlation between high CD133 levels and a positive prognosis. This review summarizes and discusses the existing evidence for and against the prognostic significance of CD133 in cancer. We also consider possible reasons for conflicting findings from the studies of the clinical significance of CD133.

JMJD6-BRD4 complex stimulates lncRNA HOTAIR transcription by binding to the promoter region of HOTAIR and induces radioresistance in liver cancer stem cells

BACKGROUND

Long non-coding RNA (lncRNA) HOTAIR acts importantly in liver cancer development, but its effect on radioresistance remains poorly understood. Here, our study probed into the possible impact of HOTAIR in radioresistance in liver cancer stem cells (LCSCs) and to elucidate its molecular basis.

METHODS

Following sorting of stem and non-stem liver cancer cells, LCSCs were identified and subjected to RNA-seq analysis for selecting differentially expressed genes. Expression of HOTAIR was determined in liver cancer tissues and CSCs. The stemness, proliferation, apoptosis and radioresistance of LCSCs were then detected in response to altered expression of HOTAIR-LSD1-JMJD6-BRD4.

RESULTS

Ectopic HOTAIR expression was found to promote radioresistance of LCSCs by maintaining its stemness. Mechanistic investigations indicated that HOTAIR recruited LSD1 to the MAPK1 promoter region and reduced the level of H3K9me2 in the promoter region, thus elevating ERK2 (MAPK1) expression. JMJD6-BRD4 complex promoted HOTAIR transcription by forming a complex and positively regulated ERK2 (MAPK1) expression, maintaining the stemness of LCSCs, and ultimately promoting their radioresistance in vitro and in vivo.

CONCLUSION

Collectively, our work highlights the promoting effect of the JMJD6-BRD4 complex on the radioresistance of LCSCs through a HOTAIR-dependent mechanism.

The role of interferon-gamma and its receptors in gastrointestinal cancers

Gastrointestinal malignancies are the most prevalent type of cancer around the world. Even though numerous studies have evaluated gastrointestinal malignancies, the actual underlying mechanism is still unknown. These tumors have a poor prognosis and are frequently discovered at an advanced stage. Globally, there is an increase in the incidence and mortality of gastrointestinal malignancies, including those of the stomach, esophagus, colon, liver, and pancreas. Growth factors and cytokines are signaling molecules that are part of the tumor microenvironment and play a significant role in the development and spread of malignancies. IFN-γ induce its effects by activation of intracellular molecular networks. The main pathway involved in IFN-γ signaling is the JAK/STAT pathway, which regulates the transcription of hundreds of genes and mediates various biological responses. IFN-γ receptor is composed of two IFN-γR1 chains and two IFN-γR2 chains. Binding to IFN-γ, causes the intracellular domains of IFN-γR2 to oligomerize and transphosphorylate with IFN-γR1 which activates downstream signaling components: JAK1 and JAK2. These activated JAKs phosphorylate the receptor, creating binding sites for STAT1. STAT1 is then phosphorylated by JAK, resulting in the formation of STAT1 homodimers (gamma activated factors or GAFs) that translocate to the nucleus and regulate gene expression. The balance between positive and negative regulation of this pathway is crucial for immune responses and tumorigenesis. In this paper, we evaluate the dynamic roles of IFN- γ and its receptors in gastrointestinal cancers and present evidence that inhibiting IFN- γ signaling may be an effective treatment strategy.

Genetic heterogeneity of liver cancer stem cells

Cancer cell heterogeneity is a serious problem in the control of tumor progression because it can cause chemoresistance and metastasis. Heterogeneity can be generated by various mechanisms, including genetic evolution of cancer cells, cancer stem cells (CSCs), and niche heterogeneity. Because the genetic heterogeneity of CSCs has been poorly characterized, the genetic mutation status of CSCs was examined using Exome-Seq and RNA-Seq data of liver cancer. Here we show that different surface markers for liver cancer stem cells (LCSCs) showed a unique propensity for genetic mutations. Cluster of differentiation 133 (CD133)-positive cells showed frequent mutations in the IRF2, BAP1, and ERBB3 genes. However, leucine-rich repeat-containing G protein-coupled receptor 5-positive cells showed frequent mutations in the CTNNB1, RELN, and ROBO1 genes. In addition, some genetic mutations were frequently observed irrespective of the surface markers for LCSCs. BAP1 mutations was frequently observed in CD133-, CD24-, CD13-, CD90-, epithelial cell adhesion molecule-, or keratin 19-positive LCSCs. ASXL2, ERBB3, IRF2, TLX3, CPS1, and NFATC2 mutations were observed in more than three types of LCSCs, suggesting that common mechanisms for the development of these LCSCs. The present study provides genetic heterogeneity depending on the surface markers for LCSCs. The genetic heterogeneity of LCSCs should be considered in the development of LCSC-targeting therapeutics.

Portal vein tumor thrombosis in hepatocellular carcinoma: molecular mechanism and therapy

Portal vein tumor thrombosis (PVTT), a common complication of advanced hepatocellular carcinoma (HCC), remains the bottleneck of the treatments. Liver cancer cells potentially experienced multi-steps during PVTT process, including cancer cells leave from cancer nest, migrate in extracellular matrix, invade the vascular barrier, and colonize in the portal vein. Accumulated evidences have revealed numerous of molecular mechanisms including genetic and epigenetic regulation, cancer stem cells, immunosuppressive microenvironment, hypoxia, et al. contributed to the PVTT formation. In this review, we discuss state-of-the-art PVTT research on the potential molecular mechanisms and experimental models. In addition, we summarize PVTT-associated clinical trials and current treatments for PVTT and suppose perspectives exploring the molecular mechanisms and improving PVTT-related treatment for the future.

Biological impact and therapeutic perspective of targeting PI3K/Akt signaling in hepatocellular carcinoma: Promises and Challenges

Cancer progression results from activation of various signaling networks. Among these, PI3K/Akt signaling contributes to proliferation, invasion, and inhibition of apoptosis. Hepatocellular carcinoma (HCC) is a primary liver cancer with high incidence rate, especially in regions with high prevalence of viral hepatitis infection. Autoimmune disorders, diabetes mellitus, obesity, alcohol consumption, and inflammation can also lead to initiation and development of HCC. The treatment of HCC depends on the identification of oncogenic factors that lead tumor cells to develop resistance to therapy. The present review article focuses on the role of PI3K/Akt signaling in HCC progression. Activation of PI3K/Akt signaling promotes glucose uptake, favors glycolysis and increases tumor cell proliferation. It inhibits both apoptosis and autophagy while promoting HCC cell survival. PI3K/Akt stimulates epithelial-to-mesenchymal transition (EMT) and increases matrix-metalloproteinase (MMP) expression during HCC metastasis. In addition to increasing colony formation capacity and facilitating the spread of tumor cells, PI3K/Akt signaling stimulates angiogenesis. Therefore, silencing PI3K/Akt signaling prevents aggressive HCC cell behavior. Activation of PI3K/Akt signaling can confer drug resistance, particularly to sorafenib, and decreases the radio-sensitivity of HCC cells. Anti-cancer agents, like phytochemicals and small molecules can suppress PI3K/Akt signaling by limiting HCC progression. Being upregulated in tumor tissues and clinical samples, PI3K/Akt can also be used as a biomarker to predict patients' response to therapy.

Prospects and feasibility of synergistic therapy with radiotherapy, immunotherapy, and DNA methyltransferase inhibitors in non-small cell lung cancer

The morbidity and mortality of lung cancer are increasing, seriously threatening human health and life. Non-small cell lung cancer (NSCLC) has an insidious onset and is not easy to be diagnosed in its early stage. Distant metastasis often occurs and the prognosis is poor. Radiotherapy (RT) combined with immunotherapy, especially with immune checkpoint inhibitors (ICIs), has become the focus of research in NSCLC. The efficacy of immunoradiotherapy (iRT) is promising, but further optimization is necessary. DNA methylation has been involved in immune escape and radioresistance, and becomes a game changer in iRT. In this review, we focused on the regulation of DNA methylation on ICIs treatment resistance and radioresistance in NSCLC and elucidated the potential synergistic effects of DNA methyltransferases inhibitors (DNMTis) with iRT. Taken together, we outlined evidence suggesting that a combination of DNMTis, RT, and immunotherapy could be a promising treatment strategy to improve NSCLC outcomes.

Role of microRNA-regulated cancer stem cells in recurrent hepatocellular carcinoma

Among the most common cancers, hepatocellular carcinoma (HCC) has a high rate of tumor recurrence, tumor dormancy, and drug resistance after initial successful chemotherapy or radiotherapy. A small subset of cancer cells, cancer stem cells (CSCs), exhibit stem cell characteristics and are present in various cancers, including HCC. The dysregulation of microRNAs (miRNAs) often accompanies the occurrence and development of HCC. miRNAs can influence tumorigenesis, progression, recurrence, and drug resistance by regulating CSCs properties, which supports their clinical utility in managing and treating HCC. This review summarizes the regulatory effects of miRNAs on CSCs in HCC with a special focus on their impact on HCC recurrence.

Inhibition of Autophagy Promotes the Elimination of Liver Cancer Stem Cells by CD133 Aptamer-Targeted Delivery of Doxorubicin

Doxorubicin is the most frequently used chemotherapeutic agent for the treatment of hepatocellular carcinoma. However, one major obstacle to the effective management of liver cancer is the drug resistance derived from the cancer stem cells. Herein, we employed a CD133 aptamer for targeted delivery of doxorubicin into liver cancer stem cells to overcome chemoresistance. Furthermore, we explored the efficacy of autophagy inhibition to sensitize liver cancer stem cells to the treatment of CD133 aptamer-doxorubicin conjugates based on the previous observation that doxorubicin contributes to the survival of liver cancer stem cells by activating autophagy. The kinetics and thermodynamics of aptamer-doxorubicin binding, autophagy induction, cell apoptosis, and self-renewal of liver cancer stem cells were studied using isothermal titration calorimetry, Western blot analysis, annexin V assay, and tumorsphere formation assay. The aptamer-cell binding andintracellular accumulation of doxorubicin were quantified via flow cytometry. CD133 aptamer-guided delivery of doxorubicin resulted in a higher doxorubicin concentration in the liver cancer stem cells. The combinatorial treatment strategy of CD133 aptamer-doxorubicin conjugates and an autophagy inhibitor led to an over 10-fold higher elimination of liver cancer stem cells than that of free doxorubicin in vitro. Future exploration of cancer stem cell-targeted delivery of doxorubicin in conjunction with autophagy inhibition in vivo may well lead to improved outcomes in the treatment of hepatocellular carcinoma.

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.

Demethylzeylasteral targets lactate by inhibiting histone lactylation to suppress the tumorigenicity of liver cancer stem cells

Cancer stem cells drive tumor initiation, progression, and recurrence, which compromise the effectiveness of anti-tumor drugs. Here, we report that demethylzeylasteral (DML), a triterpene anti-tumor compound, suppressed tumorigenesis of liver cancer stem cells (LCSCs) by interfering with lactylation of a metabolic stress-related histone. Using RNA sequencing (RNA-seq) and gas chromatography-mass spectrometric (GC-MS) analysis, we showed that the glycolysis metabolic pathway contributed to the anti-tumor effects of DML, and then focused on lactate downstream regulation as the molecular target. Mechanistically, DML opposed the progress of hepatocellular carcinoma (HCC), which was efficiently facilitated by the increase in H3 histone lactylation. Two histone modification sites: H3K9la and H3K56la, which were found to promote tumorigenesis, were inhibited by DML. In addition, we used a nude mouse tumor xenograft model to confirm that the anti-liver cancer effects of DML are mediated by regulating H3 lactylation in vivo. Our findings demonstrate that DML suppresses the tumorigenicity induced by LCSCs by inhibiting H3 histone lactylation, thus implicating DML as a potential candidate for the supplementary treatment of hepatocellular carcinoma.

Recent trends in the application of nanoparticles in cancer therapy: The involvement of oxidative stress

In the biomedical area, the interdisciplinary field of nanotechnology has the potential to bring numerous unique applications, including better tactics for cancer detection, diagnosis, and therapy. Nanoparticles (NPs) have been the topic of many research and material applications throughout the last decade. Unlike small-molecule medications, NPs are defined by distinct physicochemical characteristics, such as a large surface-to-volume ratio, which allows them to permeate live cells with relative ease. The versatility of NPs as both therapeutics and diagnostics makes them ideal for a broad spectrum of illnesses, from infectious diseases to cancer. A significant amount of data has been participated in the current scientific publications, emphasizing the concept that NPs often produce reactive oxygen species (ROS) to a larger degree than micro-sized particles. It is important to note that oxidative stress governs a wide range of cell signaling cascades, many of which are responsible for cancer cell cytotoxicity. Here, we aimed to provide insight into the signaling pathways triggered by oxidative stress in cancer cells in response to several types of nanomaterials, such as metallic and polymeric NPs and quantum dots. We discuss recent advances in developing integrated anticancer medicines based on NPs targeted to destroy malignant cells by increasing their ROS setpoint.

Alanine–Glyoxylate Aminotransferase Sustains Cancer Stemness Properties through the Upregulation of SOX2 and OCT4 in Hepatocellular Carcinoma Cells

Liver cancer stem cells (LCSCs) are a small subset of oncogenic cells with a self-renewal ability and drug resistance, and they promote the recurrence and metastasis of hepatocellular carcinoma (HCC). However, the mechanisms regulating LCSCs have not been fully explored. By enriching LCSCs from spheroid cultures and performing transcriptomic analysis, we determined that alanine–glyoxylate aminotransferase (AGXT), which participates in the metabolism of serine and glycine, was significantly upregulated in spheroid cultures, and its function in LCSCs remains unknown. Through the exogenous overexpression or short hairpin RNA knockdown of AGXT in HCC cells, we observed that changes in the AGXT level did not affect the spheroid ability and population of LCSCs. The knockdown of AGXT in LCSCs reduced the number of spheroids and the population of LCSCs; this implies that AGXT is required for the maintenance of cancer stemness rather than as a driver of LCSCs. Mechanistically, AGXT may sustain the self-renewal potential of LCSCs by upregulating the expression of SRY-box transcription factor 2 (SOX2) and octamer-binding transcription factor 4 (OCT4), two well-known master regulators of cancer stemness. Taken together, our study demonstrates the role of AGXT in supporting LCSCs; thus, AGXT merits further exploration.

Withania somnifera Modulates Radiation-Induced Generation of Lung Cancer Stem Cells via Restraining the Hedgehog Signaling Factors

Cancer stem cells (CSCs) are implicated in the genesis, development, and recurrence of lung cancer (LC) with great resistance to radiation and chemotherapy. The aim of this study is to assess the inhibitory potential of ethanol extract of Withania somnifera (WS); 500 mg/kg body-weight/day and 8 Gy of ionizing radiation (IR) could inhibit the stemness gene and confer the radiosensitizing effect of W. somnifera extract in the female rat LC model. Compared to IR or WS, the in vitro assay showed that WS + IR potentiates proliferation-inhibition and cell death of the A-549 cell line and suppresses sphere formation. The Hedgehog (Hh) signaling associated with the expression levels of lung CSC markers, octamer-binding transcription factor-4 (OCT4), SRY-box 2 (SOX2), CD133, ATP Binding Cassette Subfamily G Member 2 (ABCG2), and NANOG was upregulated with stimulated epithelial-to-mesenchymal transition (EMT) indicators α-smooth muscle actin (α-SMA), Drosophila embryonic protein (SNAIL-1), Vimentin, and E-cadherin in the LC rat model. The W. somnifera extract plus IR inhibits Hh activation factors, which has resulted in the suppression of CSC gene markers and EMT factors. W. somnifera extract may be a significant adjuvant in the course of radiotherapy, contributing to the termination of tumor progression, and thus providing cure insights into the molecular mechanisms of lung CSCs intervention.

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.

Repurposing of Anticancer Stem Cell Drugs in Brain Tumors

Brain tumors in adults may be infrequent when compared with other cancer etiologies, but they remain one of the deadliest with bleak survival rates. Current treatment modalities encompass surgical resection, chemotherapy, and radiotherapy. However, increasing resistance rates are being witnessed, and this has been attributed, in part, to cancer stem cells (CSCs). CSCs are a subpopulation of cancer cells that reside within the tumor bulk and have the capacity for self-renewal and can differentiate and proliferate into multiple cell lineages. Studying those CSCs enables an increasing understanding of carcinogenesis, and targeting CSCs may overcome existing treatment resistance. One approach to weaponize new drugs is to target these CSCs through drug repurposing which entails using drugs, which are Food and Drug Administration-approved and safe for one defined disease, for a new indication. This approach serves to save both time and money that would otherwise be spent in designing a totally new therapy. In this review, we will illustrate drug repurposing strategies that have been used in brain tumors and then further elaborate on how these approaches, specifically those that target the resident CSCs, can help take the field of drug repurposing to a new level.

Epigenetic Changes Affecting the Development of Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma is a life-threatening disease. Despite many efforts to understand the exact pathogenesis and the signaling pathways involved in its formation, treatment remains unsatisfactory. Currently, an important function in the development of neoplastic diseases and treatment effects is attributed to changes taking place at the epigenetic level. Epigenetic studies revealed modified methylation patterns in HCC, dysfunction of enzymes engaged in the DNA methylation process, the aberrant function of non-coding RNAs, and a set of histone modifications that influence gene expression. The aim of this review is to summarize the current knowledge on the role of epigenetics in the formation of hepatocellular carcinoma.

Abstract

Hepatocellular carcinoma (HCC) remains a serious oncologic issue with still a dismal prognosis. So far, no key molecular mechanism that underlies its pathogenesis has been identified. Recently, by specific molecular approaches, many genetic and epigenetic changes arising during HCC pathogenesis were detected. Epigenetic studies revealed modified methylation patterns in HCC tumors, dysfunction of enzymes engaged in the DNA methylation process, and a set of histone modifications that influence gene expression. HCC cells are also influenced by the disrupted function of non-coding RNAs, such as micro RNAs and long non-coding RNAs. Moreover, a role of liver cancer stem cells in HCC development is becoming evident. The reversibility of epigenetic changes offers the possibility of influencing them and regulating their undesirable effects. All these data can be used not only to identify new therapeutic targets but also to predict treatment response. This review focuses on epigenetic changes in hepatocellular carcinoma and their possible implications in HCC therapy.

High FRMD3 expression is prognostic for worse survival in rectal cancer patients treated with CCRT

BACKGROUND

Rectal cancer patients can conceivably obtain relief from neoadjuvant concurrent chemoradiotherapy (CCRT) for downstaging before resection, but the stratification of risk and clinical outcomes remains challenging. Therefore, identifying effective predictive biomarkers offers clinicians the opportunity to individually tailor early interventions, which would help optimize therapy.

METHODS

Using a public rectal cancer transcriptome dataset (GSE35452), we focused on cytoskeletal protein binding (GO: 0008092)-related genes and identified FERM domain containing 3 (FRMD3) as the most significant differentially expressed gene associated with CCRT resistance. We gathered 172 tumor samples from rectal cancer patients treated with neoadjuvant CCRT accompanied by curative resection and estimated the expression level of FRMD3 using immunohistochemistry.

RESULTS

The results revealed that high FRMD3 immunoexpression was remarkably associated with advanced pre-CCRT and post-CCRT tumor status (p = 0.004 and p < 0.001), pre-CCRT and post-CCRT lymph node metastasis (both p < 0.001), more perineurial invasion (p = 0.023), and a smaller extent of tumor regression (p = 0.018). High FRMD3 immunoexpression was remarkably correlated with inferior disease-specific survival (DSS) (p = 0.0001), local recurrence-free survival (LRFS) (p = 0.0003), and metastasis-free survival (MeFS) (p = 0.0023) at the univariate level. Furthermore, in multivariate analysis, high FRMD3 immunoexpression remained independently predictive of inferior DSS (p = 0.002), LRFS (p = 0.005), and MeFS (p = 0.015).

CONCLUSION

These results suggest that high FRMD3 expression is related to advanced clinicopathological features and inferior therapeutic responses in rectal cancer patients treated with CCRT, validating the promising prognostic value of FRMD3 expression.

The role of CD133 in hepatocellular carcinoma

Cancer stem cells (CSCs) represent a small subpopulation of cells found within tumors that exhibit properties of self-renewal, like normal stem cells. CSCs have been defined as a crucial factor involved in driving cancer relapse, chemoresistance and metastasis. Prominin-1 (CD133) is one of the most well-characterized markers of CSCs in various tumor types, including hepatocellular carcinoma (HCC). CD133+ cells have been demonstrated to be involved in metastasis, tumorigenesis, tumor recurrence, and resistance to treatment in HCC. CD133-related clinical prognosis prediction, and targeted therapy have highlighted the clinical significance of CD133 in HCC. However, there remains controversy over the role of CD133 in experimental and clinical research involving HCC. In this article, we summarize the fundamental cell biology of CD133 in HCC cells and discuss the important characteristics of CD133+ in HCC cells. Furthermore, the prognostic value of CD133, and therapeutic strategies for its targeting in HCC, is also reviewed.

Oncolytic virotherapy promotes radiosensitivity in soft tissue sarcoma by suppressing anti-apoptotic MCL1 expression

Soft tissue sarcoma (STS) is a rare cancer that develops from soft tissues in any part of the body. Despite major advances in the treatment of STS, patients are often refractory to conventional radiotherapy, leading to poor prognosis. Enhancement of sensitivity to radiotherapy would therefore improve the clinical outcome of STS patients. We previously revealed that the tumor-specific, replication-competent oncolytic adenovirus OBP-301 kills human sarcoma cells. In this study, we investigated the radiosensitizing effect of OBP-301 in human STS cells. The in vitro antitumor effect of OBP-301 and ionizing radiation in monotherapy or combination therapy was assessed using highly radiosensitive (RD-ES and SK-ES-1) and moderately radiosensitive (HT1080 and NMS-2) STS cell lines. The expression of markers for apoptosis and DNA damage were evaluated in STS cells after treatment. The therapeutic potential of combination therapy was further analyzed using SK-ES-1 and HT1080 cells in subcutaneous xenograft tumor models. The combination of OBP-301 and ionizing radiation showed a synergistic antitumor effect in all human STS cell lines tested, including those that show different radiosensitivity. OBP-301 was found to enhance irradiation-induced apoptosis and DNA damage via suppression of anti-apoptotic myeloid cell leukemia 1 (MCL1), which was expressed at higher levels in moderately radiosensitive cell lines. The combination of OBP-301 and ionizing radiation showed a more profound antitumor effect compared to monotherapy in SK-ES-1 (highly radiosensitive) and HT1080 (moderately radiosensitive) subcutaneous xenograft tumors. OBP-301 is a promising antitumor reagent to improve the therapeutic potential of radiotherapy by increasing radiation-induced apoptosis in STS.

A combination of sorafenib and radiotherapy reduces NF-κB activity and growth of hepatocellular carcinoma in an orthotopic mouse model

Hepatocellular carcinoma (HCC) is difficult to diagnose at an early stage, and its prognosis is generally poor. Sorafenib is the primary treatment for unresectable advanced HCC and targets multiple receptor tyrosine kinases. However, sorafenib only extends the average survival time by 3 months. This observation indicates that sorafenib may need to be combined with other treatments to further improve outcomes. We previously showed that combination of sorafenib with radiotherapy (RT) enhances tumor inhibition in subcutaneous HCC mouse models compared with monotherapy. The present study demonstrated that combining sorafenib and RT could suppress tumor growth in an orthotopic HCC model by regulating apoptosis and NF-κB-related pathways. Moreover, decreased numbers of visible liver tumors and a smaller percentage of spleen metastases were found in the combination group. A transient drop in body weight was initially observed after RT, but progressive recovery of body weight occurred. The current study showed that the combination of sorafenib and RT could be a safe strategy for HCC treatment.

Evaluation of piperine against cancer stem cells (CSCs) of hepatocellular carcinoma: Insights into epithelial-mesenchymal transition (EMT)

Cancer stem cells (CSCs) are involved in recurrent hepatocellular carcinoma (HCC), yet there is a lack of effective treatment that targets these CSCs. CD44+ and CD133+ CSCs are markedly expressed in HepG2 cells and were isolated and characterized using fluorescence-activated cell sorting (FACS) analysis. Since piperine is known as an effective molecule against metastasis, we thought to investigate the effect of piperine against CD44+/CD133+ CSCs. Herein, piperine was found to be active against these CSCs. Also, it was found appropriate to respite at the 'subG₀/G₁ and G₀/G₁' phase of the cell cycle analysis, respectively. TGF-β activated epithelial-mesenchymal transition (EMT) has been involved in the invasion and metastasis of HepG2 cells in hepatocellular carcinoma. Therefore, we next investigated the effect of piperine on different biomarkers that remarkably takes part in the process of EMT using flow cytometric analysis. Piperine was found able to repress the epithelial marker (E-cadherin) but was unable to restore the level of Vimentin (mesenchymal marker) and SNAIL (EMT-inducing transcription factor). Therefore, the findings of this study revealed that piperine could be an effective treatment strategy for recurrent hepatocarcinogenesis.

Cancer Stem Cell Metabolism

Cancer stem cells (CSCs), also known as tumorinitiating cells (TICs), are a group of cells found within cancer cells. Like normal stem cells, CSCs can proliferate, engage in self-renewal, and are often implicated in the recurrence of tumors after therapy [1, 2]. The existence of CSCs in various types of cancer has been proven, such as in acute myeloid leukemia (AML) [3], breast [4], pancreatic [5], and lung cancers [6], to name a few. There are two theories regarding the origin of CSCs. First, CSCs may have arisen from normal stem/progenitor cells that experienced changes in their environment or genetic mutations. On the other hand, CSCs may also have originated from differentiated cells that underwent genetic and/or heterotypic modifications [7]. Either way, CSCs reprogram their metabolism in order to support tumorigenesis.

EpCAM-high liver cancer stem cells resist natural killer cell-mediated cytotoxicity by upregulating CEACAM1

Background

Natural killer (NK) cells can recognize and kill cancer cells directly, but their activity can be attenuated by various inhibitory molecules expressed on the surface. The expression of epithelial cell adhesion molecule (EpCAM), a potential marker for cancer stem cells (CSCs), is known to be strongly associated with poor clinical outcomes in hepatocellular carcinoma (HCC). NK cells targeting CSCs may be a promising strategy for anti-tumor therapy, but little is known about how they respond to EpCAM^high CSCs in HCC.

Methods

EpCAM expression was assessed by immunohistochemistry in 280 human HCC tissues obtained from curative surgery. To investigate the functional activity of NK cells against liver CSCs, EpCAM^high and EpCAM^low Huh-7 cells were sorted by flow cytometry. The functional role of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), which is related to NK cells, was determined by in vitro co-culture of NK cells and hepatoma cells using Hepa1–6 mouse hepatoma cells, as well as in vivo experiments using C57/BL6 mice.

Results

The frequency of recurrence after curative surgery was higher in patients with positive EpCAM expression than in those with negative EpCAM expression. In subsequent analysis based on the anatomical location of EpCAM expression, patients with peritumoral EpCAM expression showed worse prognosis than those with pantumoral EpCAM expression. Co-culture experiments demonstrated that CEACAM1 was upregulated on the surface of EpCAM^high HCC cells, resulting in resistance to NK cell-mediated cytotoxicity. Inversely, silencing CEACAM1 restored cytotoxicity of NK cells against EpCAM^high Huh-7 cells. Moreover, neutralizing CEACAM1 on the NK cell surface enhanced killing of Huh-7 cells, suggesting that homophilic interaction of CEACAM1 is responsible for attenuated NK cell–mediated killing of CEACAM1^high cells. In mouse experiments with Hepa1–6 cells, EpCAM^high Hepa1–6 cells formed larger tumors and showed higher CEACAM1 expression after NK cell depletion. NK-mediated cytotoxicity was enhanced after blocking CEACAM1 expression using the anti-CEACAM1 antibody, thereby facilitating tumor regression. Moreover, CEACAM1 expression positively correlated with EpCAM expression in human HCC tissues, and serum CEACAM1 levels were also significantly higher in patients with EpCAM⁺ HCC.

Conclusion

Our data demonstrated that EpCAM^high liver CSCs resist NK cell–mediated cytotoxicity by upregulation of CEACAM1 expression.

Magnetic nanomedicine for CD133-expressing cancer therapy using locoregional hyperthermia combined with chemotherapy

Aim: Cells with CD133 overexpression, a theoretical cancer stem cells (CSCs) marker, have been shown to induce colorectal cancer (CRC) initiation and relapse. Therefore, the detection and treatment of CSCs are the most important factors in overcoming CRC. Materials & methods: Herein, we developed a magnetite-based nanomedicine (superparamagnetic iron oxide@poly(sodium styrene sulfonate)/irinotecan/human serum albumin-anti-CD133 nanoparticle) using loco-regional hyperthermia combined with chemotherapy for CRC- and CSC-specific targeting treatment. Results: The designed nanoparticles were highly biocompatible and exhibited a higher temperature increase rate under radiofrequency generator irradiation. The nanoparticles could be used as a T2-weighted magnetic resonance imaging contrast media, and also applied during hyperthermia and chemotherapy to display a synergistic anticancer effect. Conclusion: Therefore, the superparamagnetic iron oxide@poly(sodium styrene sulfonate)/irinotecan/human serum albumin-anti-CD133 nanoparticles are a powerful candidate for future antitumor strategies.

Discovery of VEGFR-2 inhibitors exerting significant anticancer activity against CD44+ and CD133+ cancer stem cells (CSCs): Reversal of TGF-β induced epithelial-mesenchymal transition (EMT) in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignancy characterized by neoangiogenesis, which is an augmented production of proangiogenic factors by the tumor and its adjacent infected cells. These dysregulated angiogenic factors are the therapeutic targets in anti-angiogenic drug development. The signaling pathway of vascular endothelial growth factor (VEGF)/VEGFR-2 is crucial for controlling the angiogenic responses in endothelial cells (ECs). In this study, we carried out a rational drug design approach wherein we have identified the novel orally bioavailable compound VS 8 as a potent VEGFR-2 inhibitor, which remarkably suppresses hVEGF and hVEGFR-2 expression in HUVECs and exhibits significant anti-angiogenic effects in CAM assay. Besides, VS 8 significantly induces apoptosis in HCC cell line (Hep G2). Later we examined its effectiveness against CD44+ and CD133+ CSCs. Here, VS 8 was found to be active against CSCs, and adequate for the cessation of the cell cycle at 'G₀/G₁' and 'S' phase in CD44+ and CD133+ CSCs respectively. Factually, transforming growth factor-β (TGF-β) stimulated epithelial-mesenchymal transition (EMT) induces invasion and migration of HCC cells, which results in the metastasis. Therefore, we studied the effect of VS 8 on EMT markers using flow cytometry, which suggested that VS 8 significantly upregulates E-cadherin (epithelial biomarker) and downregulates vimentin (mesenchymal biomarker). Further, VS 8 downregulates the expression of EMT-inducing transcription factors (EMT-TFs), i.e., SNAIL. Altogether, our findings indicate that VS 8 could be a promising drug candidate for cancer therapy.

Synergistic Effect of α-Solanine and Cisplatin Induces Apoptosis and Enhances Cell Cycle Arrest in Human Hepatocellular Carcinoma Cells

AIM

The clinical application of cisplatin is limited by severe side effects associated with high applied doses. The synergistic effect of a combination treatment of a low dose of cisplatin with the natural alkaloid α-solanine on human hepatocellular carcinoma cells was evaluated.

METHODS

HepG2 cells were exposed to low doses of α-solanine and cisplatin, either independently or in combination. The efficiency of this treatment modality was evaluated by investigating cell growth inhibition, cell cycle arrest, and apoptosis enhancement.

RESULTS

α-solanine synergistically potentiated the effect of cisplatin on cell growth inhibition and significantly induced apoptosis. This synergistic effect was mediated by inducing cell cycle arrest at the G2/M phase, enhancing DNA fragmentation and increasing apoptosis through the activation of caspase 3/7 and/or elevating the expression of the death receptors DR4 and DR5. The induced apoptosis from this combination treatment was also mediated by reducing the expression of the anti-apoptotic mediators Bcl-2 and survivin, as well as by modulating the miR-21 expression.

CONCLUSION

Our study provides strong evidence that a combination treatment of low doses of α-solanine and cisplatin exerts a synergistic anticancer effect and provides an effective treatment strategy against hepatocellular carcinoma.

Therapeutic Targeting of Signaling Pathways Related to Cancer Stemness

The theory of cancer stem cells (CSCs) proposes that the different cells within a tumor, as well as metastasis deriving from it, are originated from a single subpopulation of cells with self-renewal and differentiation capacities. These cancer stem cells are supposed to be critical for tumor expansion and metastasis, tumor relapse and resistance to conventional therapies, such as chemo- and radiotherapy. The acquisition of these abilities has been attributed to the activation of alternative pathways, for instance, WNT, NOTCH, SHH, PI3K, Hippo, or NF-κB pathways, that regulate detoxification mechanisms; increase the metabolic rate; induce resistance to apoptotic, autophagic, and senescence pathways; promote the overexpression of drug transporter proteins; and activate specific stem cell transcription factors. The elimination of CSCs is an important goal in cancer therapeutic approaches because it could decrease relapses and metastatic dissemination, which are main causes of mortality in oncology patients. In this work, we discuss the role of these signaling pathways in CSCs along with their therapeutic potential.

Novel molecular targets in hepatocellular carcinoma

Globally, hepatocellular carcinoma (HCC) is a leading cause of cancer and cancer-related deaths. The therapeutic efficacy of locoregional and systemic treatment in patients with advanced HCC remains low, which results in a poor prognosis. The development of sorafenib for the treatment of HCC has resulted in a new era of molecular targeted therapy for this disease. However, the median overall survival was reported to be barely higher in the sorafenib treatment group than in the control group. Hence, in this review we describe the importance of developing more effective targeted therapies for the management of advanced HCC. Recent investigations of molecular signaling pathways in several cancers have provided some insights into developing molecular therapies that target critical members of these signaling pathways. Proteins involved in the Hedgehog and Notch signaling pathways, Polo-like kinase 1, arginine, histone deacetylases and Glypican-3 can be potential targets in the treatment of HCC. Monotherapy has limited therapeutic efficacy due to the development of inhibitory feedback mechanisms and induction of chemoresistance. Thus, emphasis is now on the development of personalized and combination molecular targeted therapies that can serve as ideal therapeutic strategies for improved management of HCC.

β-radiating radionuclides in cancer treatment, novel insight into promising approach

Targeted radionuclide therapy, known as molecular radiotherapy is a novel therapeutic module in cancer medicine. β-radiating radionuclides have definite impact on target cells via interference in cell cycle and particular signalings that can lead to tumor regression with minimal off-target effects on the surrounding tissues. Radionuclides play a remarkable role not only in apoptosis induction and cell cycle arrest, but also in the amelioration of other characteristics of cancer cells. Recently, application of novel β-radiating radionuclides in cancer therapy has been emerged as a promising therapeutic modality. Several investigations are ongoing to understand the underlying molecular mechanisms of β-radiating elements in cancer medicine. Based on the radiation dose, exposure time and type of the β-radiating element, different results could be achieved in cancer cells. It has been shown that β-radiating radioisotopes block cancer cell proliferation by inducing apoptosis and cell cycle arrest. However, physical characteristics of the β-radiating element (half-life, tissue penetration range, and maximum energy) and treatment protocol determine whether tumor cells undergo cell cycle arrest, apoptosis or both and to which extent. In this review, we highlighted novel therapeutic effects of β-radiating radionuclides on cancer cells, particularly apoptosis induction and cell cycle arrest.

CSC Radioresistance: A Therapeutic Challenge to Improve Radiotherapy Effectiveness in Cancer

Radiotherapy (RT) is a modality of oncologic treatment that can be used to treat approximately 50% of all cancer patients either alone or in combination with other treatment modalities such as surgery, chemotherapy, immunotherapy, and therapeutic targeting. Despite the technological advances in RT, which allow a more precise delivery of radiation while progressively minimizing the impact on normal tissues, issues like radioresistance and tumor recurrence remain important challenges. Tumor heterogeneity is responsible for the variation in the radiation response of the different tumor subpopulations. A main factor related to radioresistance is the presence of cancer stem cells (CSC) inside tumors, which are responsible for metastases, relapses, RT failure, and a poor prognosis in cancer patients. The plasticity of CSCs, a process highly dependent on the epithelial–mesenchymal transition (EMT) and associated to cell dedifferentiation, complicates the identification and eradication of CSCs and it might be involved in disease relapse and progression after irradiation. The tumor microenvironment and the interactions of CSCs with their niches also play an important role in the response to RT. This review provides a deep insight into the characteristics and radioresistance mechanisms of CSCs and into the role of CSCs and tumor microenvironment in both the primary tumor and metastasis in response to radiation, and the radiobiological principles related to the CSC response to RT. Finally, we summarize the major advances and clinical trials on the development of CSC-based therapies combined with RT to overcome radioresistance. A better understanding of the potential therapeutic targets for CSC radiosensitization will provide safer and more efficient combination strategies, which in turn will improve the live expectancy and curability of cancer patients.

Radiotherapy targeting cancer stem cells "awakens" them to induce tumour relapse and metastasis in oral cancer

Radiotherapy is one of the most common treatments for oral cancer. However, in the clinic, recurrence and metastasis of oral cancer occur after radiotherapy, and the underlying mechanism remains unclear. Cancer stem cells (CSCs), considered the “seeds” of cancer, have been confirmed to be in a quiescent state in most established tumours, with their innate radioresistance helping them survive more easily when exposed to radiation than differentiated cancer cells. There is increasing evidence that CSCs play an important role in recurrence and metastasis post-radiotherapy in many cancers. However, little is known about how oral CSCs cause tumour recurrence and metastasis post-radiotherapy. In this review article, we will first summarise methods for the identification of oral CSCs and then focus on the characteristics of a CSC subpopulation induced by radiation, hereafter referred to as “awakened” CSCs, to highlight their response to radiotherapy and potential role in tumour recurrence and metastasis post-radiotherapy as well as potential therapeutics targeting CSCs. In addition, we explore potential therapeutic strategies targeting these “awakened” CSCs to solve the serious clinical challenges of recurrence and metastasis in oral cancer after radiotherapy.

Cancer associated fibroblasts-derived exosomes contribute to radioresistance through promoting colorectal cancer stem cells phenotype

Radioresistance observed in patients with colorectal cancer (CRC) may be related to the presence of cancer stem cells (CSCs), but the underlying mechanism(s) remain unclear. Cancer-associated fibroblasts (CAFs) can regulate the stemness of cancer cells and tumor radiosensitivity. In addition, exosomes have been reported to modify treatment response by mediating cell-cell communication. In this study, we aimed to investigate whether exosomes derived from CAFs (CAF-exosomes) are involved in mediating resistance to radiotherapy in colorectal cancer and to explore the underlying mechanism. We found that CSCs were inherently resistant to cell death induced by radiotherapy. CAF-derived CM promoted clonogenicity and radioresistance of CRC cells. Further investigations revealed that exosomes isolated from CM induced the above effects whereas exosome-depleted CM (solution) was not able to induce clonogenicity and radioresistance. Finally, exosomes could activate transforming growth factor-β (TGF-β) signaling pathway and TGFβ1-neutralizing antibody inhibit this effect and decrease clonogenicity and expression levels of stemness genes. In conclusion,our findings suggest CAFs promote stemness of CRC cells and thus increase radiation resistance. Exosomes derived from CAFs play a crucial role through activating TGF-β signaling pathway in this process.

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.

CCND1 silencing suppresses liver cancer stem cell differentiation and overcomes 5-Fluorouracil resistance in hepatocellular carcinoma

OBJECTIVE

Chemoresistance is one of the major barriers in chemotherapy-based hepatocellular carcinoma (HCC) intervention. 5-Fluorouracil (5-Fu) is a widely used as an anticancer drug. Liver cancer stem cells (LCSCs) are considered the origin of tumor recurrence and resistance. CCND1 (Cyclin D1) plays an important role in tumorigenesis and metastasis in multiple cancers including HCC. Herein, this study was designed to explore the role of CCND1 in regulating LCSCs differentiation and 5-Fu resistance in HCC cells.

METHODS

The CCND1 mRNA level was examined by qRT-PCR. The protein levels of γ-H2AX (a DNA damage marker) and RAD51 (a DNA repair protein) were examined by Western blot. CD133 was used as a LCSC marker and CD133+ cell percentage in HCC cells was detected by flow cytometry.

RESULTS

CCND1 silencing decreased CD133+ cell percentage in HepG2 and SMMC-7721 cells. Furthermore, CCND1 silencing significantly increased protein level of γ-H2AX and decreased that of RAD51 under 5-Fu exposure. Moreover, CCND1 silencing enhanced the sensitivity of HepG2 and SMMC-7721 cells to 5-Fu, which was effectively abrogated by RAD51 upregulation.

CONCLUSION

Collectively, CCND1 silencing suppresses LCSCs differentiation and overcomes 5-Fu resistance in HCC.

Combination Therapy With Charged Particles and Molecular Targeting: A Promising Avenue to Overcome Radioresistance

Radiotherapy plays a central role in the treatment of cancer patients. Over the past decades, remarkable technological progress has been made in the field of conventional radiotherapy. In addition, the use of charged particles (e.g., protons and carbon ions) makes it possible to further improve dose deposition to the tumor, while sparing the surrounding healthy tissues. Despite these improvements, radioresistance and tumor recurrence are still observed. Although the mechanisms underlying resistance to conventional radiotherapy are well-studied, scientific evidence on the impact of charged particle therapy on cancer cell radioresistance is restricted. The purpose of this review is to discuss the potential role that charged particles could play to overcome radioresistance. This review will focus on hypoxia, cancer stem cells, and specific signaling pathways of EGFR, NFκB, and Hedgehog as well as DNA damage signaling involving PARP, as mechanisms of radioresistance for which pharmacological targets have been identified. Finally, new lines of future research will be proposed, with a focus on novel molecular inhibitors that could be used in combination with charged particle therapy as a novel treatment option for radioresistant tumors.

Stem Cell Markers Predict the Response to Sorafenib in Patients with Hepatocellular Carcinoma

Background/Aims

Sorafenib remains the only approved molecular targeted agent for hepatocellular carcinoma (HCC); however, reliable biomarkers that predict its efficacy are still lacking. The aim of this study was to explore whether cancer stem cell (CSC) markers have a predictive role with regard to the sorafenib response in HCC patients.

Methods

We enrolled 47 patients with HCC for whom tumor samples obtained before starting sorafenib treatment were available. RNA was extracted from formalin-fixed, paraffin-embedded samples, and real-time polymerase chain reaction was used to quantify mRNA expression of the CSC genes EpCAM, CD13, CK8, CD24, CD44, CD90, CD133, SALL4, ALDH1A1, ALB, and AFP.

Results

Of 47 patients, 14.9% and 74.5% had vascular invasion and extrahepatic spread, respectively. Patients with low CD133 expression tended to have longer progression-free survival (PFS) than those with high CD133 expression (5.5 months vs 4.0 months), although without statistical significance. The expression levels of other markers were not associated with PFS. When examining markers in combination, patients with high CD133 and CD90 expression had shorter PFS rates than those with low expression (2.7 months vs 5.5 months; p=0.04). Patients with low CD133 and EpCAM expression demonstrated better PFS than those with high expression (7.0 months vs 4.2 months; p=0.04). Multivariable analysis indicated that an Eastern Cooperative Oncology Group performance status score of 1 and high CD133/CD90 expression were significantly associated with shorter PFS.

Conclusions

Overexpression of the CSC markers CD133 and CD90 in HCC was associated with poorer response to sorafenib. These two genes may serve as predictive biomarkers for sorafenib therapy.

Cancer stem cells and nanotechnological approaches for eradication

Cancer stem cells (CSCs) are currently known as the main cause of tumor recurrence. After chemotherapy is completed, CSCs proliferate and then differentiate to generate new tumor tissues. Similar to normal stem cells, this non-uniformly distributed cell population in the tumor tissue has self-renewal capacity and is responsible for survival of the tumor and difference in its genetic and metabolic characteristics. Followed by gene instability in CSCs, new phenotypic markers are aberrantly expressed in CSCs subpopulation. Hence, some of the surface markers and metabolic pathways that are upregulated in CSCs may be applied as specific targets for development of diagnostic and therapeutic approaches. In this review article, the distinctive properties of CSCs including signal pathways implicated in self-renewal and surface markers were discussed. Moreover, targeting CSCs based on their specific properties using nanodrugs was reviewed.

CCND1 silencing suppresses liver cancer stem cell differentiation through inhibiting autophagy

Liver cancer stem cells (LCSCs) are responsible for the carcinogenesis, recurrence, metastasis and chemoresistance of hepatocellular carcinoma (HCC). This study aimed to explore the role of CCND1 (Cyclin D1), an oncogene in HCC, in regulating LCSC differentiation and to elucidate whether autophagy was involved in this process. The CCND1 mRNA level was examined by qRT-PCR. The protein levels of autophagy markers (Becin-1 and LC3II) were examined by western blot to evaluate autophagy level. CD133 was used as a LCSC marker and CD133 + cell percentage in HCC cells was detected by flow cytometry. Immunohistochemistry staining was performed to detect CD133 expression in SMMC-7721 cell-implanted tumor sections. The results showed that CCND1 expression was higher in HCC cell lines than that in normal hepatocyte L02 cells. Furthermore, CCND1 overexpression increased CD133 + cell percentage and protein levels of Becin-1 and LC3II in HepG2 and SMMC-7721 HCC cells. In contrast, CCND1 silencing exerted the opposite effect. Moreover, treatment with the autophagy activator rapamycin effectively abrogated the CCND1 silencing-reduced CD133 + cell percentage. Further in vivo assays demonstrated that CCND1 silencing decreased expression of CD133, Becin-1 and LC3II in xenograft tumors of SMMC-7721 cells. Taken together, CCND1 silencing suppresses LCSC differentiation through inhibiting autophagy.

Redox regulation of cell state and fate

The failure in effective cancer treatment is thought to be attributed to a subpopulation of tumor cells with stem cell-like properties. These cancer stem cells (CSCs) are intimately linked to tumor initiation, heterogeneity, maintenance, recurrence and metastasis. Increasing evidence supports the view that a tight redox regulation is crucial for CSC proliferation, tumorigenicity, therapy resistance and metastasis in many cancer types. Since the distinct metabolic and epigenetic states of CSCs may influence ROS levels, and hence their malignancy, ROS modulating agents hold promise in their utility as anti-CSC agents that may improve the durability of current cancer treatments. This review will focus on (i) how ROS levels are regulated for CSCs to elicit their hallmark features; (ii) the link between ROS and metabolic plasticity of CSCs; and (iii) how ROS may interface with epigenetics that would enable CSCs to thrive in a stressful tumor microenvironment and survive therapeutic insults.

Roles of mitochondria in liver cancer stem cells

Primary liver cancer (PLC) is heterogeneous and it is an aggressive malignancy with a poor prognostic outcome. Current evidence suggests that PLC tumorigenesis is driven by rare subpopulations of cancer stem cells (CSCs), which contribute to tumor initiation, progression, and therapy resistance through particular molecular mechanisms. Energy metabolism and mitochondrial function play an important role in the regulation of cancer stemness and stem cell specifications. Since the role of mitochondrial function as central hubs in cell growth and survival, studies on the critical physiological mechanisms of the liver underlying their therapy-resistant phenotype is important. In this review, we focus on liver CSC-related mitochondrial metabolism that contributes to the liver CSC features, in terms of enhanced drug-resistance and increased tumorigenicity, and to discuss their roles on potential therapies windows for PLC therapies.

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.

Co-expression and prognostic significance of putative CSC markers CD44, CD133, wild-type EGFR and EGFRvIII in metastatic colorectal cancer

The presence of colorectal cancer stem cells (CSCs) have been associated with tumour initiation and resistance to therapy. This study investigated the co-expression and prognostic significance of the CSCs biomarkers CD44 and CD133 with wild-type EGFR (wtEGFR) and EGFRvIII in colorectal cancer (CRC). The expression of these biomarkers were determined in tumours from 70 patients with metastatic CRC by immunohistochemistry, and in a panel of human CRC cell lines, and their variants with acquired-resistance to EGFR inhibitors, by flow cytometry. The expression of CD44, CD133, wtEGFR and EGFRvIII were present in 17%, 23%, 26% and 13% of cases and the co-expression of CD44/CD133 with wtEGFR and EGFRvIII were present in 9% and 3% of the cases respectively. Only co-expression of CSCs/EGFRvIII (P = 0.037), and amphiregulin (P = 0.017) were associated with worse overall survival. Interestingly, disease-free survival was improved in BTC expressing patients (P = 0.025). In vitro CD133 expression and its co-expression with CD44 were associated with primary-resistance to irinotecan and acquired-resistance to anti-EGFR inhibitors respectively. Our results suggest co-expression of CSCs and EGFRvIII could be potential biomarkers of worse overall survival and resistance to therapy in patients with mCRC and warrants further validation in a larger cohort.

CXCL11 promotes self-renewal and tumorigenicity of α2δ1+ liver tumor-initiating cells through CXCR3/ERK1/2 signaling

Tumor-initiating cells (TICs), which are responsible for sustaining tumor growth and recurrence, rely on several regulatory factors. However, the mechanism of inflammation-related molecules in the acquisition and maintenance of TIC properties in hepatocellular carcinoma (HCC) remains elusive. We previously demonstrated that the voltage-gated calcium channel α2δ1 subunit is a functional surface marker of HCC TICs. Here, we found that the expression of an inflammation-related molecule C-X-C motif chemokine 11 (CXCL11) was significantly upregulated in α2δ1⁺ HCC TICs and that CXCL11 induced the expression of stem cell-related genes, such as BMI1, NANOG, MDR1, ABCG2, and CACNA2D1. Furthermore, CXCL11 could promote the acquisition and maintenance of self-renewal, tumorigenic, and chemoresistance properties of α2δ1⁺ HCC TICs by activating the extracellular signal-regulated kinase (ERK1/2) through its affinity receptor CXCR3. Collectively, our results suggest that CXCL11 may positively regulate the stemness of α2δ1⁺ HCC TICs via ERK1/2 activation through an autocrine signaling pathway.