Long non-coding RNA THOR promotes liver cancer stem cells expansion via β-catenin pathway

Association between lncRNAs with stem cells in cancer; a particular focus on lncRNA-CSCs axis in cancer immunopathogenesis

A unique population of cells known as cancer stem cells (CSCs) is essential to developing and spreading cancer. Cancer initiation, maintenance, and progression are all believed to be significantly impacted by the distinct characteristics these cells exhibit regarding self-renewal, proliferation, and differentiation. Transcriptional, post-transcriptional, and translational processes are the only steps of gene expression that lncRNAs can affect. As a result, these proteins participate in numerous biological processes, including the repair of DNA damage, inflammatory reactions, metabolic control, the survival of cells, intercellular communication, and the development and specialization of cells. Studies have indicated that lncRNAs are important for controlling the increase in the subset of CSCs contributing to cancer development. The knowledge that is currently available about lncRNAs and their critical role in maintaining the biological properties of CSCs is highlighted in this study.

Research Progress of Long Non-Coding RNA in Tumor Drug Resistance: A New Paradigm

In the past few decades, chemotherapy has been one of the most effective cancer treatment options. Drug resistance is currently one of the greatest obstacles to effective cancer treatment. Even though drug resistance mechanisms have been extensively investigated, they have not been fully elucidated. Recent genome-wide investigations have revealed the existence of a substantial quantity of long non-coding RNAs (lncRNAs) transcribed from the human genome, which actively participate in numerous biological processes, such as transcription, splicing, epigenetics, the cell cycle, cell differentiation, development, pluripotency, immune microenvironment. The abnormal expression of lncRNA is considered a contributing factor to the drug resistance. Furthermore, drug resistance may be influenced by genetic and epigenetic variations, as well as individual differences in patient treatment response, attributable to polymorphisms in metabolic enzyme genes. This review focuses on the mechanism of lncRNAs resistance to target drugs in the study of tumors with high mortality, aiming to establish a theoretical foundation for targeted therapy.

The occurrence and development of induced pluripotent stem cells

The ectopic expression of four transcription factors, Oct3/4, Sox2, Klf4, and c-Myc (OSKM), known as "Yamanaka factors," can reprogram or stimulate the production of induced pluripotent stem cells (iPSCs). Although OSKM is still the gold standard, there are multiple ways to reprogram cells into iPSCs. In recent years, significant progress has been made in improving the efficiency of this technology. Ten years after the first report was published, human pluripotent stem cells have gradually been applied in clinical settings, including disease modeling, cell therapy, new drug development, and cell derivation. Here, we provide a review of the discovery of iPSCs and their applications in disease and development.

New insights into the interaction between m6A modification and lncRNA in cancer drug resistance

Drug resistance is perhaps the greatest obstacle in improving outcomes for cancer patients, leading to recurrence, progression and metastasis of various cancers. Exploring the underlying mechanism worth further study. N6-methyladenosine (m6A) is the most common RNA modification found in eukaryotes, playing a vital role in RNA translation, transportation, stability, degradation, splicing and processing. Long noncoding RNA (lncRNA) refers to a group of transcripts that are longer than 200 nucleotides (nt) and typically lack the ability to code for proteins. LncRNA has been identified to play a significant role in regulating multiple aspects of tumour development and progression, including proliferation, metastasis, metabolism, and resistance to treatment. In recent years, a growing body of evidence has emerged, highlighting the crucial role of the interplay between m6A modification and lncRNA in determining the sensitivity of cancer cells to chemotherapeutic agents. In this review, we focus on the recent advancements in the interaction between m6A modification and lncRNA in the modulation of cancer drug resistance. Additionally, we aim to explore the underlying mechanisms involved in this process. The objective of this review is to provide valuable insights and suggest potential future directions for the reversal of chemoresistance in cancer.

WNT/β-catenin signaling in hepatocellular carcinoma: The aberrant activation, pathogenic roles, and therapeutic opportunities

Hepatocellular carcinoma (HCC) is a liver cancer, highly heterogeneous both at the histopathological and molecular levels. It arises from hepatocytes as the result of the accumulation of numerous genomic alterations in various signaling pathways, including canonical WNT/β-catenin, AKT/mTOR, MAPK pathways as well as signaling associated with telomere maintenance, p53/cell cycle regulation, epigenetic modifiers, and oxidative stress. The role of WNT/β-catenin signaling in liver homeostasis and regeneration is well established, whereas in development and progression of HCC is extensively studied. Herein, we review recent advances in our understanding of how WNT/β-catenin signaling facilitates the HCC development, acquisition of stemness features, metastasis, and resistance to treatment. We outline genetic and epigenetic alterations that lead to activated WNT/β-catenin signaling in HCC. We discuss the pivotal roles of CTNNB1 mutations, aberrantly expressed non-coding RNAs and complexity of crosstalk between WNT/β-catenin signaling and other signaling pathways as challenging or advantageous aspects of therapy development and molecular stratification of HCC patients for treatment.

The lncRNA lnc-TSI antagonizes sorafenib resistance in hepatocellular carcinoma via downregulating miR-4726-5p expression and upregulating KCNMA1 expression

Acquired drug resistance is a main reason for limiting the application of sorafenib in HCC treatment. This study aimed to explore the role and mechanisms of a novel long non-coding RNA (lncRNA), lnc-TSI, in sorafenib resistance of HCC. The interaction between lnc-TSI and miR-4726-5p, and miR-4726-5p and KCNMA1 were predicted using bioinformatic tools. Expression of the molecules in the lnc-TSI/miR-4726-5p/KCNMA1 axis in clinical samples and cell lines, as well as the sorafenib resistant HCC cell lines, was determined using qRT-PCR or western blotting. Expressions of lnc-TSI, miR-4726-5p, and KCNMA1 were manipulated in HepG2 and Huh7 cells through plasmid transfection or lentivirus infection. The CCK-8, flow cytometry, and Tunel assays were employed to determine the role of this axis on sorafenib resistance of HCC. A xenograft model was established using sorafenib-resistant HepG2 and Huh7 cells followed by in vivo sorafenib treatments to confirm the in vitro findings. Lnc-TSI and KCNMA1 expressions were significantly downregulated in HCC clinical samples and cell lines, especially in sorafenib resistance ones, while mi-4726-5p presented a reversed expression pattern. Lnc-TSI interacted with miR-4726-5p, and Lnc-TSI acts as a ceRNA via sponging miR-4726-5p in HCC cells. Overexpression of lnc-TSI and KCNMA1 promoted apoptosis and decreased cell viability of sorafenib-treated HCC cells, thus alleviated sorafenib resistance. miR-4726-5p mimic reversed the KCNMA1-mediated sorafenib sensitivity-promoting effect, while additional overexpression of lnc-TSI reversed the effect of miR-4726-5p. In vivo analysis also showed that overexpression of ln-TSI diminished sorafenib resistance in mice inoculated with sorafenib-resistant HCC cells via increasing KCNMA1 expression and decreasing miR-4726-5p expression. The lnc-TSI/miR-4726-5p/KCNMA1 axis plays a critical role in regulating the resistance of HCC to sorafenib, and might serve as a therapeutic target to manage sorafenib resistance of HCC in clinic.

Combating drug resistance in hepatocellular carcinoma: No awareness today, no action tomorrow

Hepatocellular carcinoma (HCC), the sixth most common cancer worldwide, is associated with a high degree of malignancy and poor prognosis. Patients with early HCC may benefit from surgical resection to remove tumor tissue and a margin of healthy tissue surrounding it. Unfortunately, most patients with HCC are diagnosed at an advanced or distant stage, at which point resection is not feasible. Systemic therapy is now routinely prescribed to patients with advanced HCC; however, drug resistance has become a major obstacle to the treatment of HCC and exploring purported mechanisms promoting drug resistance remains a challenge. Here, we focus on the determinants of drug resistance from the perspective of non-coding RNAs (ncRNAs), liver cancer stem cells (LCSCs), autophagy, epithelial-mesenchymal transition (EMT), exosomes, ferroptosis, and the tumor microenvironment (TME), with the aim to provide new insights into HCC treatment.

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.

A Water-Soluble Hydrogen Sulfide Donor Suppresses the Growth of Hepatocellular Carcinoma via Inhibiting the AKT/GSK-3β/β-Catenin and TGF-β/Smad2/3 Signaling Pathways

Hepatocellular carcinoma (HCC) is a disease with high morbidity, high mortality, and low cure rate. Hyaluronic acid (HA) is widely adopted in tissue engineering and drug delivery. 5-(4-Hydroxyphenyl)-3H-1, 2-dithiol-3-thione (ADT-OH) is one of commonly used H₂S donors. In our previous study, HA-ADT was designed and synthesized via coupling of HA and ADT-OH. In this study, compared with sodium hydrosulfide (NaHS, a fast H₂S-releasing donor) and morpholin-4-ium (4-methoxyphenyl)-morpholin-4-ylsulfanylidenesulfido-λ5-phosphane (GYY4137, a slow H₂S-releasing donor), HA-ADT showed stronger inhibitory effect on the proliferation, migration, invasion, and cell cycle of human HCC cells. HA-ADT promoted apoptosis by suppressing the expressions of phospho (p)-protein kinase B (PKB/AKT), p-glycogen synthase kinase-3β (GSK-3β), p-β-catenin, and also inhibited autophagy via the downregulation of the protein levels of p-Smad2, p-Smad3, and transforming growth factor-β (TGF-β) in human HCC cells. Moreover, HA-ADT inhibited HCC xenograft tumor growth more effectively than both NaHS and GYY4137. Therefore, HA-ADT can suppress the growth of HCC cells by blocking the AKT/GSK-3β/β-catenin and TGF-β/Smad2/3 signaling pathways. HA-ADT and its derivatives may be developed as promising antitumor drugs.

Hepatocellular Carcinoma: Current Therapeutic Algorithm for Localized and Advanced Disease

Hepatocellular carcinoma (HCC) is the most common primary liver cancer in patients with liver cirrhosis of various etiologies. In recent years, there has been an advance in the knowledge of molecular mechanisms and a better staging definition of patients which has allowed the development of new therapies that have entered the therapeutic workup of these patients. Deep information on molecular drivers of HCC contributed to the development of targeted therapies with remarkable benefits. The novel strategies of targeting immune evasion using immune checkpoint inhibitors and CAR-T and TCR-T therapeutics have also shown promising results. For advanced diseases, the therapeutic algorithm has been recently updated, thanks to the efficacy of combining immunotherapy and antiangiogenic therapy in the first-line setting, and new drugs, both as single-agents or combinations, are currently under investigation.

WTAP-mediated m6A modification on circCMTM3 inhibits hepatocellular carcinoma ferroptosis by recruiting IGF2BP1 to increase PARK7 stability

BACKGROUND

Hepatocellular carcinoma (HCC) has poor prognosis and high mortality. CircCMTM3 was significantly up-regulated in HCC. However, the mechanism of circCMTM3 in HCC is not full elucidated.

METHODS

The expression level of circCMTM3, PARK7, GPX4, and Ki67 in HCC cells and tissues were quantified by qRT-PCR, IHC, and Western blotting. The level of GSH, total iron, Fe²⁺, and MDA were detected by their kits. CCK-8 and flow cytometry analysis were used to evaluated cell proliferation and lipid ROS level, respectively. m6A level of circCMTM3 was assessed by MeRIP-PCR. RNA pulldown, RIP, and FISH detected the interaction between circCMTM3, WTAP, and PARK7. Tumor xenograft model was constructed to validate the function of cicrCMTM3 and WTAP.

RESULTS

CircCMTM3 and WTAP were enhanced in HCC tissues and cells. Knockdown of WTAP inhibited m6A modification of circCMTM3, which promoted HCC ferroptosis. circCMTM3 silencing suppressed the expression and stability of PARK7 through binding with IGF2BP1 in HCC cells, which finally induced ferroptosis. In vivo studies demonstrated that silencing WTAP and circCMTM3 suppressed tumor growth and promoted HCC ferroptosis in nude mice by regulating PARK7 signaling.

CONCLUSION

CircCMTM3 promoted the carcinogenesis through inhibiting ferroptosis by recruiting IGF2BP1 to increase PARK7 stability in HCC, suggesting that cicrCMTM3 may be an important marker for HCC treatment.

Understanding the versatile roles and applications of EpCAM in cancers: from bench to bedside

Epithelial cell adhesion molecule (EpCAM) functions not only in physiological processes but also participates in the development and progression of cancer. In recent decades, extensive efforts have been made to decipher the role of EpCAM in cancers. Great advances have been achieved in elucidating its structure, molecular functions, pathophysiological mechanisms, and clinical applications. Beyond its well-recognized role as a biomarker of cancer stem cells (CSCs) or circulating tumor cells (CTCs), EpCAM exhibits novel and promising value in targeted therapy. At the same time, the roles of EpCAM in cancer progression are found to be highly context-dependent and even contradictory in some cases. The versatile functional modules of EpCAM and its communication with other signaling pathways complicate the study of this molecule. In this review, we start from the structure of EpCAM and focus on communication with other signaling pathways. The impacts on the biology of cancers and the up-to-date clinical applications of EpCAM are also introduced and summarized, aiming to shed light on the translational prospects of EpCAM.

Influence of Long Non-Coding RNA in the Regulation of Cancer Stem Cell Signaling Pathways

Over the past two decades, cancer stem cells (CSCs) have emerged as an immensely studied and experimental topic, however a wide range of questions concerning the topic still remain unanswered; in particular, the mechanisms underlying the regulation of tumor stem cells and their characteristics. Understanding the cancer stem-cell signaling pathways may pave the way towards a better comprehension of these mechanisms. Signaling pathways such as WNT, STAT, Hedgehog, NOTCH, PI3K/AKT/mTOR, TGF-β, and NF-κB are responsible not only for modulating various features of CSCs but also their microenvironments. Recently, the prominent roles of various non-coding RNAs such as small non-coding RNAs (sncRNAs) and long non-coding RNAs (lncRNAs) in developing and enhancing the tumor phenotypes have been unfolded. This review attempts to shed light on understanding the influence of long non- coding RNAs in the modulation of various CSC-signaling pathways and its impact on the CSCs and tumor properties; highlighting the protagonistic and antagonistic roles of lncRNAs.

LncRNA THOR promotes endometrial cancer progression through the AKT and ERK signaling pathways

The long noncoding RNA (lncRNA) THOR is highly conserved and expressed in various human cancer tissues, although its potential role and underlying mechanism in endometrial cancer (EC) remain unknown. This study aims to explore THOR's biological function and molecular mechanism in EC progression. THOR expression in EC tissues and cell lines was detected by quantitative reverse transcription PCR (qRT-PCR) and in situ hybridization (ISH). THOR expression based on The Cancer Genome Atlas (TCGA) and clinical sample analyses was significantly higher in EC tissues than normal tissues, and higher THOR levels were closely associated with poor overall survival in EC. Additionally, a positive correlation between ISH-detected THOR expression and pathological grade was observed. CCK-8, colony formation, and transwell migration and invasion assays revealed that THOR significantly enhances the proliferation, migration, and invasion abilities of EC cells. Moreover, IGF2BP1 protein expression and ERK and AKT protein phosphorylation levels in EC cells increased significantly with THOR overexpression in EC cells. In conclusion, our findings suggest that THOR promotes EC cell growth and invasion, and IGF2BP1-mediated AKT and ERK signaling pathways activation might be involved. Clinically, THOR is significantly expressed in EC, and high THOR expression correlates with poor prognosis, making it a potential prognostic marker for EC.

Oncogenic Role of ADAM32 in Hepatoblastoma: A Potential Molecular Target for Therapy

Outcomes of pediatric hepatoblastoma (HBL) have improved, but refractory cases still occur. More effective and safer drugs are needed that are based on molecular mechanisms. A disintegrin and metalloproteases (ADAMs) are expressed with high frequency in various human carcinomas and play an important role in cancer progression. In this study, we analyzed expression of ADAMs in HBL with a cDNA microarray dataset and found that the expression level of ADAM32 is particularly high. To investigate the role of ADAM32 in cancer, forced expression or knockdown experiments were conducted with HepG2 and HBL primary cells. Colony formation, cell migration and invasion, and cell viability were increased in HepG2 expressing ADAM32, whereas knockdown of ADAM32 induced a decrease in these cellular functions. Quantitative RT-PCR demonstrated an association between ADAM32 expression and the expression of genes related to cancer stem cells and epithelial–mesenchymal transition (EMT), suggesting a role of ADAM32 in cancer stemness and EMT. Furthermore, knockdown of ADAM32 increased cisplatin-induced apoptosis, and this effect was attenuated by a caspase-8 inhibitor, suggesting that ADAM32 plays a role in extrinsic apoptosis signaling. We conclude that ADAM32 plays a crucial role in progression of HBL, so it might be a promising molecular target in anticancer therapy.

The Roles of Noncoding RNAs in the Development of Osteosarcoma Stem Cells and Potential Therapeutic Targets

Osteosarcoma (OS) is the common bone tumor in children and adolescents. Because of chemotherapy resistance, the OS patients have a poor prognosis. The one reason of chemotherapeutic resistance is the development of cancer stem cells (CSCs). CSCs represent a small portion of tumor cells with the capacity of self-renewal and multipotency, which are associated with tumor initiation, metastasis, recurrence and drug resistance. Recently, noncoding RNAs (ncRNAs) have been reported to critically regulate CSCs. Therefore, in this review article, we described the role of ncRNAs, especially miRNAs, lncRNAs and circRNAs, in regulating CSCs development and potential mechanisms. Specifically, we discussed the role of multiple miRNAs in targeting CSCs, including miR-26a, miR-29b, miR-34a, miR-133a, miR-143, miR-335, miR-382, miR-499a, miR-1247, and let-7days. Moreover, we highlighted the functions of lncRNAs in regulating CSCs in OS, such as B4GALT1-AS1, DANCR, DLX6-AS1, FER1L4, HIF2PUT, LINK-A, MALAT1, SOX2-OT, and THOR. Due to the critical roles of ncRNAs in regulation of OS CSCs, targeting ncRNAs might be a novel strategy for eliminating CSCs for OS therapy.

Long Non-Coding RNA THOR Depletion Inhibits Human Non-Small Cell Lung Cancer Cell Growth

Long non-coding RNA (LncRNA) THOR (Lnc-THOR) is expressed in testis and multiple human malignancies. Lnc-THOR association with IGF2BP1 (IGF2 mRNA-binding protein 1) is essential for stabilization and transcription of IGF2BP1 targeted mRNAs. We tested its expression and potential functions in non-small cell lung cancer (NSCLC). In primary NSCLC cells and established cell lines, Lnc-THOR shRNA or CRISPR/Cas9-mediated knockout (KO) downregulated IGF2BP1 target mRNAs (IGF2, Gli1, Myc and SOX9), inhibiting cell viability, growth, proliferation, migration and invasion. Significant apoptosis activation was detected in Lnc-THOR-silenced/-KO NSCLC cells. Conversely, ectopic overexpression of Lnc-THOR upregulated IGF2BP1 mRNA targets and enhanced NSCLC cell proliferation, migration and invasion. RNA-immunoprecipitation and RNA pull-down assay results confirmed the direct binding between Lnc-THOR and IGF2BP1 protein in NSCLC cells. Lnc-THOR silencing and overexpression were ineffective in IGF2BP1-KO NSCLC cells. Forced IGF2BP1 overexpression failed to rescue Lnc-THOR-KO NSCLC cells. In vivo, intratumoral injection of Lnc-THOR shRNA adeno-associated virus potently inhibited A549 xenograft tumor growth in nude mice. At last we show that Lnc-THOR is overexpressed in multiple NSCLC tissues and established/primary NSCLC cells. Collectively, these results highlighted the ability of Lnc-THOR in promoting NSCLC cell growth by associating with IGF2BP1, suggesting that Lnc-THOR represents a promising therapeutic target of NSCLC.

LncRNAs in tumor microenvironment: The potential target for cancer treatment with natural compounds and chemical drugs

It was thought that originally long non-coding RNAs (lncRNAs) were a kind of RNAs without any encoding function. Recently, a variety of studies have shown that lncRNAs play important roles in many life activities. The abnormal expression of lncRNAs in tumor microenvironment (TME) usually promotes the proliferation, migration, and drug resistance of tumor cells through direct or indirect effects, which also usually predicts the poor prognosis. The regulation of lncRNAs expression in TME could significantly inhibit tumor progress. However, the interaction between lncRNAs and TME has not been fully defined at present. Therefore, this paper provided the systemic summary of their interaction and natural products and chemicals targeting lncRNAs in cancer treatment. Currently, the strategies of cancer treatment still have their limits. Understanding the relationship between TME and lncRNAs can help us to realize breakthrough strategy for tumor treatment.

Emerging Regulatory Mechanisms Involved in Liver Cancer Stem Cell Properties in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the predominant form of primary liver cancer and one of the leading causes of cancer-related deaths worldwide. A growing body of evidence supports the hypothesis that HCC is driven by a population of cells called liver cancer stem cells (LCSCs). LCSCs have been proposed to contribute to malignant HCC progression, including promoting tumor occurrence and growth, mediating tumor metastasis, and treatment resistance, but the regulatory mechanism of LCSCs in HCC remains unclear. Understanding the signaling pathways responsible for LCSC maintenance and survival may provide opportunities to improve patient outcomes. Here, we review the current literature about the origin of LCSCs and the niche composition, describe the current evidence of signaling pathways that mediate LCSC stemness, then highlight several mechanisms that modulate LCSC properties in HCC progression, and finally, summarize the new developments in therapeutic strategies targeting LCSCs markers and regulatory pathways.

Effect of the Hypoxia Inducible Factor on Sorafenib Resistance of Hepatocellular Carcinoma

Sorafenib a multi-target tyrosine kinase inhibitor, is the first-line drug for treating advanced hepatocellular carcinoma (HCC). Mechanistically, it suppresses tumor angiogenesis, cell proliferation and promotes apoptosis. Although sorafenib effectively prolongs median survival rates of patients with advanced HCC, its efficacy is limited by drug resistance in some patients. In HCC, this resistance is attributed to multiple complex mechanisms. Previous clinical data has shown that HIFs expression is a predictor of poor prognosis, with further evidence demonstrating that a combination of sorafenib and HIFs-targeted therapy or HIFs inhibitors can overcome HCC sorafenib resistance. Here, we describe the molecular mechanism underlying sorafenib resistance in HCC patients, and highlight the impact of hypoxia microenvironment on sorafenib resistance.

Pluripotency inducing Yamanaka factors: role in stemness and chemoresistance of liver cancer

Introduction: Liver cancer is a major cause of mortality and is characterized by the transformation of cells into an uncontrolled mass of tumor cells with many genetic and epigenetic changes, which lead to the development of tumors. A small subpopulation of cell population known as Cancer Stem Cells (CSCs) is responsible for cancer stemness and chemoresistance. Yamanaka factors [octamer-binding transcription factor 4 (OCT4), SRY (sex-determining region Y)-box 2 (SOX2), kruppel-like factor 4 (KLF4), and Myelocytomatosis (MYC); OSKM] are responsible for cancer cell stemness, chemoresistance, and recurrence.Area covered: We cover recent discoveries and investigate the role of OSKM in inducing pluripotency and stem cell-like properties in various cancers with special emphasis on liver cancer. We review Yamanaka factors' role in stemness and chemoresistance of liver cancer.Expert opinion: In CSCs, including liver CSCs, the deregulation of various signaling pathways is one of the major reasons for stemness and drug resistance and is primarily due to OSKM. OSKM are responsible for tumor heterogeneity which renders targeting drug useless after a certain period. These factors can be exploited to understand the underlying mechanism of cancer stemness and resistance to chemotherapeutic drugs.

The clinical, prognostic and therapeutic significance of liver cancer stem cells and their markers

Hepatocellular carcinoma (HCC) is the fourth most common cause of death among cancers. The poor prognosis of HCC might be caused by a population of cancer stem cells (CSC). CSC have similar characteristics to normal stem cells and are responsible for cancer recurrence, chemoresistance, radioresistance and metastasis. Liver cancer stem cells (LCSC) are identified via specific surface markers, such as CD44, CD90, CD133, and EpCAM (CD326). Recent studies suggested a complex interaction between mentioned LCSC markers and clinical features of HCC. A high expression of CSC is correlated with a negative prognostic factor after surgical resection of HCC and is connected with more aggressive tumor behavior. Moreover, LCSC might be responsible for increasing resistance to sorafenib, a kinase inhibitor drug. A reduction in the LCSC population may be crucial to successful advanced HCC therapy.

Research Progress on Regulating LncRNAs of Hepatocellular Carcinoma Stem Cells

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies around the world. The self-renewal, proliferation, differentiation, and tumorigenic potential of liver cancer stem cells (LCSCs) may account for the high recurrence rate and the refractory feature of HCC. Despite extensive researches, the underlying regulatory mechanism of LCSCs has not been fully disclosed. Long nonprotein coding RNAs (lncRNAs) may exert an essential role in regulating various biological functions of LCSCs, such as maintaining the stemness of cancer stem cells (CSCs) and promoting tumor development. Therefore, it is highly critical to determine which lncRNAs can control LCSCs functions and understand how LCSCs are regulated by lncRNAs. Herein, we summarized lncRNAs and the main signaling pathways involved in the regulation of LCSCs found in recent years. Moreover, we shed light on the existence of the network system of lncRNAs and LCSCs, which may provide valuable clues on targeting LCSCs.

Advances in Liver Cancer Stem Cell Isolation and their Characterization

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

lncRNA-POIR promotes epithelial-mesenchymal transition and suppresses sorafenib sensitivity simultaneously in hepatocellular carcinoma by sponging miR-182-5p

Sorafenib (SOR) resistance remains a major obstacle in the effective treatment of hepatocellular carcinoma (HCC). A number of long noncoding RNAs (lncRNAs) are responsible for this chemoresistance. This study aimed to reveal the essential function of a recently defined lncRNA, lncRNA-POIR, in the epithelial-mesenchymal transition (EMT) and SOR sensitivity of HCC cells. SOR-induced cytotoxicity was analyzed via cell counting kit-8 and ethynyl-2'-deoxyuridine incorporation assays, whereas immunoblotting and confocal immunofluorescence were used to determine the expression levels of EMT markers. Furthermore, loss- or gain-of-function approaches were used to demonstrate the role of lncRNA-POIR/miR-182-5p on EMT and SOR sensitivity in HCC. The direct interaction between lncRNA-POIR and miR-182-5p was verified using a luciferase reporter assay. We found that knockdown of lncRNA-POIR sensitized HCC cells to SOR and simultaneously reversed EMT. As expected, miR-182-5p was confirmed as the downstream target of lncRNA-POIR. Moreover, miR-182-5p overexpression clearly reversed EMT and promoted SOR-induced cytotoxicity in representative HCC cells, whereas miR-182-5p downregulation played a contrasting role; miR-182-5p knockdown abolished the modulatory effects of lncRNA-POIR siRNA on EMT and SOR sensitivity. Together, these pieces of data suggest that lncRNA-POIR promotes EMT progression and suppresses SOR sensitivity simultaneously by sponging miR-182-5p. Thus, we proposed a compelling rationale for the use of lncRNA-POIR as a promising predictor of SOR response and as a potential therapeutic target for HCC treatment in the future.

LIN28B-AS1-IGF2BP1 binding promotes hepatocellular carcinoma cell progression

IGF2BP1 overexpression promotes hepatocellular carcinoma (HCC) progression. Long non-coding RNA LIN28B-AS1 directly binds to IGF2BP1. In the present study, LIN28B-AS1 and IGF2BP1 expression and their potential functions in HCC cells were tested. Genetic strategies were applied to interfere their expression, and cell survival, proliferation and apoptosis were analyzed. We show that LIN28B-AS1 is expressed in established/primary human HCC cells and HCC tissues. RNA-immunoprecipitation (RIP) and RNA pull-down results confirmed that LIN28B-AS1 directly associated with IGF2BP1 protein in HCC cells. LIN28B-AS1 silencing (by targeted siRNAs) or knockout (KO, by CRISPR-Cas9 method) depleted IGF2BP1-dependent mRNAs (IGF2, Gli1, and Myc), inhibiting HCC cell growth, proliferation, migration, and invasion. Conversely, ectopic overexpression of LIN28B-AS1 upregulated IGF2BP1-dependent mRNAs and promoted HCC cell progression in vitro. Importantly, ectopic IGF2BP1 overexpression failed to rescue LIN28B-AS1-KO HepG2 cells. LIN28B-AS1 siRNA and overexpression were ineffective in IGF2BP1-KO HepG2 cells. In vivo, LIN28B-AS1 KO-HepG2 xenograft tumors grew significantly slower than the control tumors in the nude mice. Taken together, we conclude that LIN28B-AS1 associates with IGF2BP1 to promote human HCC cell progression in vitro and in vivo.

A novel N6-methyladenosine (m6A)-dependent fate decision for the lncRNA THOR

Previous studies have revealed the critical roles of the N6-methyladenosine (m6A) modification of long non-coding RNAs (lncRNAs) in cancers, but the relationship between the oncogenic role of the lncRNA THOR (a representative of cancer/testis lncRNAs) and m6A modification remains unclear. Here, we show that the internal m6A modification of the lncRNA THOR via an m6A-reader-dependent modality regulates the proliferation of cancer cells. Our findings demonstrated that the loss of the lncRNA THOR inhibits the proliferation, migration, and invasion of cancer cells in vitro and in vivo. In addition, m6A is highly enriched on lncRNA THOR transcripts, which contain GA (m6A) CA, GG (m6A) CU, and UG (m6A) CU sequence motifs. RIP-qRT-PCR and RNA pull-down assay results revealed that the specific m6A readers YTHDF1 and YTHDF2 can read the m6A motifs and regulate the stability of the lncRNA THOR (stabilization and decay). These m6A-dependent RNA-protein interactions can maintain the oncogenic role of the lncRNA THOR. Collectively, these findings highlight the critical role of the m6A modification in oncogenic lncRNA THOR and reveal a novel long non-coding RNA regulatory mechanism, providing a new way to explore RNA epigenetic regulatory patterns in the future.

Long Non-Coding RNA THOR Enhances the Stem Cell-Like Traits of Triple-Negative Breast Cancer Cells Through Activating β-Catenin Signaling

Background

The oncogenic roles of lncRNA THOR have been revealed in several tumors, however, its functions in breast cancer are still unclear.

Material/Methods

Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect THOR expression in clinical samples and the expression of stemness regulatory factors. ALDH1 assay and sphere-formation analysis were constructed to examine the stemness of cells. Cell viability assay was constructed to determine the cell proliferation capacity. In vitro RNA-RNA interaction and messenger RNA (mRNA) stability assays were performed to explore the mechanisms.

Results

THOR was overexpressed in triple-negative breast cancer (TNBC) compared to that in luminal A- and B-type breast cancer. THOR silencing reduced TNBC cell stemness, which was evident by the decreased sphere-formation ability, stemness marker expression and ALDH1 activity. Mechanistically, THOR directly bound to β-catenin mRNA, enhanced β-catenin mRNA stability and thus increased its expression. Furthermore, overexpression of β-catenin partially diminished THOR silencing-mediated inhibition on TNBC cell stemness.

Conclusions

This work proposes that THOR facilitates TNBC cell stemness through activating β-catenin signaling.

Long noncoding RNA THOR is highly expressed in colorectal cancer and predicts a poor prognosis

Aim: Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. This study aimed to investigate the role of long noncoding RNA THOR in CRC. Materials & methods: The expression of THOR in 103 cases of CRC tissues and four CRC cell lines was examined by quantitative real-time PCR. Cell counting kit-8 and colony formation assays were applied to detect cell proliferation, and flow cytometry was used for testing cell cycle and apoptosis of CRC. Results: We found that THOR was highly expressed in CRC and correlated with tumor node metastasis stage, histological subtype, tumor size and differentiation and survival in CRC patients. Meanwhile, knockdown of THOR significantly suppressed cell proliferation and cell cycle of CRC, whereas promoted cell apoptosis. Conclusion: Our findings suggest that THOR is an oncogenic long noncoding RNA in CRC and a potential prognostic biomarker for this cancer.

Non-Coding RNAs: Regulating Disease Progression and Therapy Resistance in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), the primary liver cancer arising from hepatocytes, is a universal health problem and one of the most common malignant tumors. Surgery followed by chemotherapy as well as tyrosine kinase inhibitors (TKIs), such as sorafenib, are primary treatment procedures for HCC, but recurrence of disease because of therapy resistance results in high mortality. It is necessary to identify novel regulators of HCC for developing effective targeted therapies that can significantly interfere with progression of the disease process. Non-coding RNAs (ncRNAs) are an abundant group of versatile RNA transcripts that do not translate into proteins, rather serve as potentially functional RNAs. The role of ncRNAs in regulating diverse aspects of the carcinogenesis process are gradually being elucidated. Recent advances in RNA sequencing technology have identified a plethora of ncRNAs regulating all aspects of hepatocarcinogenesis process and serving as potential prognostic or diagnostic biomarkers. The present review provides a comprehensive description of the biological roles of ncRNAs in disease process and therapy resistance, and potential clinical application of these ncRNAs in 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.

Lnc-THOR silencing inhibits human glioma cell survival by activating MAGEA6-AMPK signaling

Long non-coding RNA THOR (Lnc-THOR) binds to IGF2BP1, essential for its function. We here show that Lnc-THOR is expressed in human glioma tissues and cells. Its expression is extremely low or even undetected in normal brain tissues, as well as in human neuronal cells and astrocytes. We show that Lnc-THOR directly binds to IGF2BP1 in established and primary human glioma cells. shRNA-mediated Lnc-THOR knockdown or CRISPR/Cas9-induced Lnc-THOR knockout potently inhibited cell survival and proliferation, while provoking glioma cell apoptosis. Contrarily, forced overexpression of Lnc-THOR promoted glioma cell growth and migration. Importantly, Lnc-THOR shRNA or knockout activated MAGEA6-AMPK signaling in glioma cells. AMPK inactivation, by AMPKα1 shRNA, knockout, or dominant-negative mutation (T172A), attenuated Lnc-THOR shRNA-induced A172 glioma cell apoptosis. Moreover, CRISPR/Cas9-induced IGF2BP1 knockout activated MAGEA6-AMPK signaling as well, causing A172 glioma cell apoptosis. Significantly, Lnc-THOR shRNA was ineffective in IGF2BP1 KO A172 cells. In vivo, Lnc-THOR silencing or knockout potently inhibited subcutaneous A172 xenograft tumor growth in mice. MAGEA6 downregulation and AMPK activation were detected in Lnc-THOR-silenced/-KO A172 tumor tissues. Taken together, Lnc-THOR depletion inhibits human glioma cell survival possibly by activating MAGEA6-AMPK signaling.

Non-coding RNAs: Emerging Regulators of Sorafenib Resistance in Hepatocellular Carcinoma

As the first oral multi-target anti-tumor drug proved for the treatment of patients with advanced liver cancer in 2007, sorafenib has changed the landscape of advanced hepatocellular carcinoma (HCC) treatment. However, drug resistance largely hinders its clinical application. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), and long non-coding (lncRNAs), have recently been demonstrated playing critical roles in a variety of cancers including HCC, while the mechanisms of ncRNAs in HCC sorafenib resistance have not been extensively characterized yet. Herein, we summarize the mechanisms of recently reported ncRNAs involved in sorafenib resistance and discuss the potential strategies for their application in the battle against HCC.

LncRNA THOR promotes tongue squamous cell carcinomas by stabilizing IGF2BP1 downstream targets

THOR, a highly conserved lncRNA, is potentially involved in various cancer development. However, its involvement in tongue squamous cell carcinoma (TSCC) remains unclear. The present study aims to explore the biological function and molecular mechanism of THOR in TSCC progression. The expressions of THOR and IGF2BP1 in TSCC tissues and adjacent non-cancerous tongue tissues (ANT) were examined through qRT-PCR. THOR levels were manipulated in TSCC cells to explore its function in cancer progression in vitro and in vivo, which were subsequently evaluated by CCK8, colony formation assay, flow cytometry, xenograft tumor assays. In situ hybridization, RIP and Western blot assay were performed to explore the underlying molecular mechanisms. We discovered that THOR and IGF2BP1 were dramatically upregulated in TSCC tissues. The expression of THOR is positively correlated with IGF2BP1 mRNA level. THOR mediated IGF2 expression via interacting with IGF2BP1, and affected the downstream MEK-ERK signaling pathway to regulate TSCC cells proliferation. THOR/IGF2BP1/IGF2-MEK-ERK axis regulated the proliferation of TSCC cells, implying that THOR would be a promising therapeutic target for TSCC patients.

Targeted therapy for hepatocellular carcinoma: Challenges and opportunities

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, which ranks as the sixth of cancer-related death. Despite the emergence of targeted therapy, advanced-stage HCC remains largely incurable due to low response rate and therapeutic resistance. In this review, we mainly focused on the current progression of multi-kinase inhibitors and immunotherapies in the treatment of HCC. We highlight the mechanism underlying the ineffectiveness of these targeted therapies, including oncogenic alterations in driver genes and downstream pathways, high heterogeneity of HCC, and the mutual interaction of tumor microenvironment that promotes therapeutic resistance. We also discussed how these previous studies suggested for future therapeutic strategies. Besides, the complexity of HCC heterogeneity and cancer revolution need to be recognized in personalized therapy. Establishment of a drug screening system and identification of biomarkers of response is also in urgent need to overcome drug resistance. Meanwhile, a combination of targeted therapies could also be explored as a promising strategy in the future.

LncRNA THOR increases osteosarcoma cell stemness and migration by enhancing SOX9 mRNA stability

Although the long non-coding RNA THOR has been reported to promote cancer stem cell expansion in liver cancer and gastric cancer, its effects on osteosarcoma (OS) cells remain unclear. Here, we investigated the roles of THOR in the stemness and migration of OS cells. We report that the level of THOR is remarkably upregulated in OS cell spheroids compared to that in OS adherent cells. THOR overexpression increased spheroid formation ability and aldehyde dehydrogenase 1 (ALDH1) activity in OS adherent cells, and the opposite effect was observed in spheroids with THOR knockdown. Additionally, the spheroids formed by OS adherent cells exhibited a stronger migration ability, which was attenuated by THOR knockdown, and THOR overexpression increased OS cell migration. Mechanistically, mRNA stability, luciferase reporter, and RNA-RNA in vitro interaction assays indicated that THOR can directly bind to the middle region of the SOX9 3'-untranslated region (UTR), and enhances its mRNA stability, thereby increasing its expression. Notably, SOX9 knockdown reduced the ability of THOR overexpression to promote the stemness of OS cells. These findings indicate that the lncRNA THOR can promote the stemness and migration of OS cells by directly binding to the middle region of SOX9 3'UTR, thereby enhancing SOX9 mRNA stability and increasing its expression; thus, we provide information that may be of use in identifying potential targets for OS treatment.