3,6-dihydroxyflavone suppresses the epithelial-mesenchymal transition in breast cancer cells by inhibiting the Notch signaling pathway

Anti-metastatic potential of flavonoids for the treatment of cancers: focus on epithelial-mesenchymal transition (EMT) process

The leading factor contributing to patient mortality is the local invasion and metastasis of tumors, which are influenced by the malignant progression of tumor cells. The epithelial-mesenchymal transition (EMT) is key to understanding malignancy development. EMT is a critical regulatory mechanism for differentiating cell populations initially observed during the neural crest and embryonic gastrulation formation. This process is closely associated with tumor metastasis in cancer and is also related to the maintenance of cancer stem cells. Flavonoids, known for their antioxidant properties, have been widely studied for their anticancer potential to protect plants from harmful environmental conditions. They have attracted considerable attention and have been the focus of numerous experimental and epidemiological studies to evaluate their potential in cancer treatment. In vitro and in vivo research has demonstrated that flavonoids can significantly impact cancer-related EMT. They may inhibit the EMT process by reducing the levels of Twist1, N-cadherin, ZEB1, integrins, SNAI1/2, CD44, MMPs, and vimentin while increasing E-cadherin levels and targeting the PI3K/AKT, NF-κB p65, and JAK2/STAT3 signaling pathways. In order to suppress the transcription of the E-cadherin promoter, several Zn-finger transcription factors, such as SNAI2, ZEB1, and ZEB2, and basic helix-loop-helix (bHLH) factors, such as Twist, may directly bind to its E-boxes. Overall, clinical cancer research should integrate the anticancer properties of flavonoids, which address all phases of carcinogenesis, including EMT, to improve the prospects for targeted cancer therapies in patients suffering from aggressive forms of tumors.

Unlocking the Potential: How Flavonoids Affect Angiogenesis, Oxidative Stress, Inflammation, Proliferation, Invasion, and Alter Receptor Interactions in Endometriosis

Endometriosis, though not classified as a carcinogenic condition, shares features such as oxidative stress, migration, invasion, angiogenesis, and inflammation with tumor cells. This study aims to review the effects of flavonoids on these processes and their molecular mechanisms in preventing and treating endometriosis. A comprehensive review was conducted, involving a literature search in online databases using keywords like "endometriosis," "endometrioma," and "flavonoid." Two authors screened the literature based on predefined criteria, and the selected studies were summarized in a structured data extraction table. Studies reviewed showed that various flavonoids impact key processes in endometriosis, including angiogenesis, inflammation, oxidative stress, and invasiveness. Flavonoids such as 2',7'-dichlorodihydrofluorescein diacetate (H2DCF-DA), naringenin, apigenin, myricetin, 5,7-dimethoxyflavone (DMF), chrysin, and 6,8-diprenylorobol were found to induce oxidative stress. Xanthohumol, isoliquiritigenin, and luteolin demonstrated effects on angiogenesis. Apigenin, isoliquiritigenin, and luteolin exhibited anti-inflammatory properties. Additionally, 3,6-dihydroxyflavone, isoliquiritigenin, and naringenin displayed anti-invasive activities. Flavonoid-receptor interactions further enhance their therapeutic potential in endometriosis management. Flavonoids such as nobiletin, chrysin, and daidzein modulate PPARγ and PPARα, reducing inflammation, promoting apoptosis, and improving lipid metabolism. These interactions regulate critical pathways in angiogenesis and immune responses. Additionally, flavonoids impact the aryl hydrocarbon receptor (AhR), with compounds like resveratrol inhibiting cell proliferation and cholesterol biosynthesis, further suppressing lesion growth. The ability of flavonoids like quercetin and kaempferol to antagonize NR4A1 leads to reduced cell proliferation and oxidative stress in endometriotic tissues. These findings offer insights into the mechanisms through which specific flavonoids modulate angiogenesis, inflammation, oxidative stress, and invasiveness in endometriosis. By targeting receptors such as PPARs, AhR, and NR4A1, flavonoids demonstrate the capacity to modulate both metabolic and inflammatory pathways, offering a multifaceted approach to managing endometriosis. Flavonoids can selectively target pathophysiologic molecules and pathways implicated in the condition. Consequently, leveraging the therapeutic attributes of flavonoids could lead to novel strategies for managing endometriosis.

Identification of novel broad-spectrum antiviral drugs targeting the N-terminal domain of the FIPV nucleocapsid protein

Coronaviruses pose serious threats to human and animal health worldwide, of which their structural nucleocapsid (N) proteins play multiple key roles in viral replication. However, the structures of animal coronavirus N proteins are poorly understood, posing challenges for research on their functions and pathogenic mechanisms as well as the development of N protein-based antiviral drugs. Therefore, N proteins must be further explored as potential antiviral targets. We determined the structure of the NNTD of feline infectious peritonitis virus (FIPV) and identified 3,6-dihydroxyflavone (3,6- DHF) as an effective N protein inhibitor. 3,6-DHF successfully inhibited FIPV replication in CRFK cells, showing broad-spectrum activity and effectiveness against drugresistant strains. Our study provides important insights for developing novel broadspectrum anti-coronavirus drugs and treating infections caused by drug-resistant mutant strains.

Targeting Notch signaling pathways with natural bioactive compounds: a promising approach against cancer

Notch signaling pathway is activated abnormally in solid and hematological tumors, which perform essential functions in cell differentiation, survival, proliferation, and angiogenesis. The activation of Notch signaling and communication among Notch and other oncogenic pathways heighten malignancy aggressiveness. Thus, targeting Notch signaling offers opportunities for improved survival and reduced disease incidence. Already, most attention has been given to its role in the cancer cells. Recent research shows that natural bioactive compounds can change signaling molecules that are linked to or interact with the Notch pathways. This suggests that there may be a link between Notch activation and the growth of tumors. Here, we sum up the natural bioactive compounds that possess inhibitory effects on human cancers by impeding the Notch pathway and preventing Notch crosstalk with other oncogenic pathways, which provoke further study of these natural products to derive rational therapeutic regimens for the treatment of cancer and develop novel anticancer drugs. This review revealed Notch as a highly challenging but promising target in oncology.

The role of flavonoids in the regulation of epithelial-mesenchymal transition in cancer: A review on targeting signaling pathways and metastasis

One of the hallmarks of cancer is metastasis, a process that entails the spread of cancer cells to distant regions in the body, culminating in tumor formation in secondary organs. Importantly, the proinflammatory environment surrounding cancer cells further contributes to cancer cell transformation and extracellular matrix destruction. During metastasis, front-rear polarity and emergence of migratory and invasive features are manifestations of epithelial-mesenchymal transition (EMT). A variety of transcription factors (TFs) are implicated in the execution of EMT, the most prominent belonging to the Snail Family Transcriptional Repressor (SNAI) and Zinc Finger E-Box Binding Homeobox (ZEB) families of TFs. These TFs are regulated by interaction with specific microRNAs (miRNAs), as miR34 and miR200. Among the several secondary metabolites produced in plants, flavonoids constitute a major group of bioactive molecules, with several described effects including antioxidant, antiinflammatory, antidiabetic, antiobesogenic, and anticancer effects. This review scrutinizes the modulatory role of flavonoids on the activity of SNAI/ZEB TFs and on their regulatory miRNAs, miR-34, and miR-200. The modulatory role of flavonoids can attenuate mesenchymal features and stimulate epithelial features, thereby inhibiting and reversing EMT. Moreover, this modulation is concomitant with the attenuation of signaling pathways involved in diverse processes as cell proliferation, cell growth, cell cycle progression, apoptosis inhibition, morphogenesis, cell fate, cell migration, cell polarity, and wound healing. The antimetastatic potential of these versatile compounds is emerging and represents an opportunity for the synthesis of more specific and potent agents.

In-vitro inhibition of NLRP3 inflammasome by 3,6-dihydroxyflavone (3,6-DHF): a therapeutic strategy for the treatment of chronic inflammatory and autoimmune diseases

Nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex has an important role in immune system and its abnormal activation is associated with the pathogenesis of various inflammatory and auto-immune diseases. The study reveals the anti-inflammatory effects of 3,6-dihydroxyflavone (3,6-DHF). Here, we aimed to determine the inhibitory effects of 3,6-DHF on NLRP3 inflammasome and its associated components, thereby determining the signaling pathways involved in the inhibition. Reactive oxygen species (ROS) and nitric oxide (NO) were quantified by chemiluminescence and Griess methods, respectively. Inflammatory cell model was induced in human leukemic monocytes (THP-1). mRNA levels were estimated through real-time RT-PCR, protein expressions were evaluated by protein slot blot and immunocytochemistry, MTT and alamar blue assays were employed for toxicity studies. The compound 3,6-DHF was found to be the potent inhibitor of NLRP3 inflammasome by targeting the molecules involve in its activation pathway. Anti-inflammatory effects were revealed by inhibition of ROS and NO, reduction in the transcription of caspase-1, ASC, IL-1β and TLR-4 was observed along with the marked inhibition of NLRP3, IL-18, NF-κB and pNF-κB at translational level. 3,6-DHF was non-toxic on normal human fibroblast (BJ) and THP-1 cells and, could be a potential therapeutic agent in NLRP3 inflammasome driven diseases.

Interaction between BEND5 and RBPJ suppresses breast cancer growth and metastasis via inhibiting Notch signaling

High frequent metastasis is the major cause of breast cancer (BC) mortality among women. However, the molecular mechanisms underlying BC metastasis remain largely unknown. Here, we identified six hub BC metastasis driver genes (BEND5, HSD11B1, NEDD9, SAA2, SH2D2A and TNFSF4) through bioinformatics analysis, among which BEND5 is the most significant gene. Low BEND5 expression predicted advanced stage and shorter overall survival in BC patients. Functional experiments showed that BEND5 could suppress BC growth and metastasis in vitro and in vivo. Mechanistically, BEND5 inhibits Notch signaling via directly interacting with transcription factor RBPJ/CSL. BEN domain of BEND5 interacts with the N-terminal domain (NTD) domain of RBPJ, thus preventing mastermind like transcriptional coactivator (MAML) from forming a transcription activation complex with RBPJ. Our study provides a novel insight into regulatory mechanisms underlying Notch signaling and suggests that BEND5 may become a promising target for BC therapy.

Notch signaling in the pathogenesis, progression and identification of potential targets for cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is an aggressive type of bile duct cancer that is characterized by a high mortality rate due to its late diagnosis and ineffective treatment. The aim of the present systematic review was to analyze the association between Notch signaling and CCA in terms of its pathogenesis, progression and potential treatment targets. Relevant information was gathered from the PubMed, ScienceDirect and Scopus databases using the search terms 'cholangiocarcinoma' AND 'Notch signaling'. Of the 90 articles identified, 28 fulfilled the eligibility criteria and were included in the analysis. It was concluded that overexpression/upregulation of Notch ligands, such as Jagged1 and Notch receptors (Notch1, Notch2 and Notch3), as well as upregulation of the upstream Notch signaling pathway, promoted CCA development and progression. In addition, downregulation of Notch1 signaling through several possible interventions appears to be a promising strategy for inhibition of CCA development and progression. Therefore, the Notch signaling pathway may be considered as a potential target for CCA control.

The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar

Background

Contrasting with zebrafish, retinal regeneration from Müller cells (MCs) is largely limited in mammals, where they undergo reactive gliosis that consist of a hypertrophic response and ultimately results in vision loss. Transforming growth factor β (TGFβ) is essential for wound healing, including both scar formation and regeneration. However, targeting TGFβ may affect other physiological mechanisms, owing its pleiotropic nature. The regulation of various cellular activities by TGFβ relies on its interaction with other pathways including Notch. Here, we explore the interplay of TGFβ with Notch and how this regulates MC response to injury in zebrafish and mice. Furthermore, we aimed to characterize potential similarities between murine and human MCs during chronic reactive gliosis.

Methods

Focal damage to photoreceptors was induced with a 532 nm diode laser in TgBAC (gfap:gfap-GFP) zebrafish (ZF) and B6-Tg (Rlbp1-GFP) mice. Transcriptomics, immunofluorescence, and flow cytometry were employed for a comparative analysis of MC response to laser-induced injury between ZF and mouse. The laser-induced injury was paired with pharmacological treatments to inhibit either Notch (DAPT) or TGFβ (Pirfenidone) or TGFβ/Notch interplay (SIS3). To determine if the murine laser-induced injury model translates to the human system, we compared the ensuing MC response to human donors with early retinal degeneration.

Results

Investigations into injury-induced changes in murine MCs revealed TGFβ/Notch interplay during reactive gliosis. We found that TGFβ1/2 and Notch1/2 interact via Smad3 to reprogram murine MCs towards an epithelial lineage and ultimately to form a glial scar. Similar to what we observed in mice, we confirmed the epithelial phenotype of human Müller cells during gliotic response.

Conclusion

The study indicates a pivotal role for TGFβ/Notch interplay in tuning MC stemness during injury response and provides novel insights into the remodeling mechanism during retinal degenerative diseases.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13024-021-00482-z.

Long Non-Coding RNA SNHG6 Supports Glioma Progression Through Upregulation of Notch1, Sox2, and EMT

Gliomas, particularly the advanced grade glioblastomas, have poor 5-year survival rates and worse outcomes. lncRNAs and EMT have been extensively studied in gliomas but the disease progression remains poorly understood. SNHG6 has been shown to affect glioma cell proliferation but its effect on EMT of glioma cells along with its effect on disease progression is not known. We screened four glioma cell lines; H4, A172, U87MG, and SW088 and grouped them based on high vs. low SNHG6 expression. Transfections with SNHG6 specific siRNA resulted in induction of apoptosis of high SNHG6 expressing A172 and U87MG cells. This was accompanied by inhibition of EMT and downregulation of EMT-modulating factor Notch1, β-catenin activity and the cancer stem cell marker Sox2. The regulation was not found to be reciprocal as silencing of Notch1 and Sox2 failed to affect SNHG6 levels. The levels of SNHG6 and Notch1 were also found elevated in Grade IV glioma patients (n = 4) relative to Grade II glioma patients (n = 5). These results identify SNHG6 and Notch1 as valid targets for glioma therapy.

RRV-induced biliary atresia in neonatal mice involves CD8 + T lymphocyte killer cells and the Notch signaling pathway

BACKGROUND

Persistent inflammation induced by viral infection may contribute to the pathogenesis of biliary atresia (BA). Moreover, CD4⁺ helper cells and CD8⁺ killer cells are the main effector cells involved in BA and intrahepatic bile duct injuries.

OBJECTIVE

Thus, we aimed to explore the dynamics of inflammatory cell infiltration and inflammation-regulated pathways in liver-specific inflammatory responses.

METHODS

Neonatal Balb/C mice were intraperitoneally infected with 1 × 10⁶ PFU rhesus rotavirus (RRV; BA + group), 1 × 10⁵ PFU RRV (BA- group), or DMEM (control group). Mice were sacrificed 7 or 14 days post-infection and their bile ducts, livers, and spleen-derived tissues were examined via H & E staining. The number of CD4⁺T lymphocytes helper cells (CD4⁺Th), CD8⁺T lymphocytes killer cells (CD8⁺Tc), natural killer (NK) cells, and macrophages (Mac) in the liver and spleen were quantified by flow cytometry. The expression of inflammatory genes was analyzed via a PCR-array. Western blotting was conducted to quantify the protein expression of Notch receptor active fragments (NICD). Finally, some mice were injected with DAPT (a γ-secretase inhibitor) 12 h post-infection followed by analysis of liver and bile duct tissues after 14 days.

RESULTS

The numbers of CD4⁺Th cells were increased in the livers of BA- mice after 14 days (P < 0.05). After RRV infection, the number of CD8⁺Tc, CD4⁺Th, NK, and Mac were increased in the livers of BA + mice after 7 and 14 days. Notably, NK cell numbers remained elevated in the BA + group, but the number of Mac first increased and then decreased in both the treatment groups. PCR-array analyses indicated that the expression of many genes related to T cell proliferation and differentiation significantly increased in the livers of BA. The most upregulated gene was Jagged2 (20.34-fold). Increased NICD (Notch receptor active fragments) protein expression was found in the BA + group. Finally, DAPT injection could reduce inflammation, CD8⁺Tc infiltration, NICD expression, and bile duct damage after RRV infection. We found that CD8⁺Tc played the most important role in damaging bile ducts and promoting BA.

CONCLUSION

The DAPT-based intervention could reduce expression of CD8⁺Tc and bile duct damage in BA mouse livers post-RRV infection. We believe that the Notch signaling pathway regulates CD8⁺Tc functions and inflammatory dynamics in BA mouse livers.

The Breast Cancer Stem Cells Traits and Drug Resistance

Drug resistance is a major challenge in breast cancer (BC) treatment at present. Accumulating studies indicate that breast cancer stem cells (BCSCs) are responsible for the BC drugs resistance, causing relapse and metastasis in BC patients. Thus, BCSCs elimination could reverse drug resistance and improve drug efficacy to benefit BC patients. Consequently, mastering the knowledge on the proliferation, resistance mechanisms, and separation of BCSCs in BC therapy is extremely helpful for BCSCs-targeted therapeutic strategies. Herein, we summarize the principal BCSCs surface markers and signaling pathways, and list the BCSCs-related drug resistance mechanisms in chemotherapy (CT), endocrine therapy (ET), and targeted therapy (TT), and display therapeutic strategies for targeting BCSCs to reverse drug resistance in BC. Even more importantly, more attention should be paid to studies on BCSC-targeted strategies to overcome the drug resistant dilemma of clinical therapies in the future.

High Expression of miR-34a Associated with Less Aggressive Cancer Biology but Not with Survival in Breast Cancer

Most breast cancer (BC) patients succumb to metastatic disease. MiR-34a is a well-known tumor suppressive microRNA which exerts its anti-cancer functions by playing a role in p53, apoptosis induction, and epithelial-mesenchymal transition (EMT) suppression. Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and The Cancer Genome Atlas (TCGA) cohorts were used to test our hypothesis that miR-34a high BCs translate to less aggressive cancer biology and better survival in large cohorts. There was no association between miR-34a expression levels and clinicopathological features of BC patients except for HER2 positivity. MiR-34a high expressing tumors were associated with lower Nottingham pathological grades and lower MKI67 expression. In agreement, high miR-34a tumors demonstrated lower GSVA scores of cell cycle and cell proliferation-related gene sets. High miR-34a tumors enriched the p53 pathway and apoptosis gene sets. Unexpectedly, high miR-34a tumors also associated with elevated EMT pathway score and ZEB1 and two expressions. MiR-34a expression did not associate with any distant metastasis. Further, high miR-34a tumors did not associate with better survival compared with miR-34a low tumors. In conclusion, the clinical relevance of miR-34a high expressing tumors was associated with suppressed cell proliferation, enhanced p53 pathway and apoptosis, but enhanced EMT and these findings did not reflect better survival outcomes in large BC patient cohorts.

Cellular plasticity and metastasis in breast cancer: a pre- and post-malignant problem

As a field we have made tremendous strides in treating breast cancer, with a decline in the past 30 years of overall breast cancer mortality. However, this progress is met with little affect once the disease spreads beyond the primary site. With a 5-year survival rate of 22%, 10-year of 13%, for those patients with metastatic breast cancer (mBC), our ability to effectively treat wide spread disease is minimal. A major contributing factor to this ineffectiveness is the complex make-up, or heterogeneity, of the primary site. Within a primary tumor, secreted factors, malignant and pre-malignant epithelial cells, immune cells, stromal fibroblasts and many others all reside alongside each other creating a dynamic environment contributing to metastasis. Furthermore, heterogeneity contributes to our lack of understanding regarding the cells' remarkable ability to undergo epithelial/non-cancer stem cell (CSC) to mesenchymal/CSC (E-M/CSC) plasticity. The enhanced invasion & motility, tumor-initiating potential, and acquired therapeutic resistance which accompanies E-M/CSC plasticity implicates a significant role in metastasis. While most work trying to understand E-M/CSC plasticity has been done on malignant cells, recent evidence is emerging concerning the ability for pre-malignant cells to undergo E-M/CSC plasticity and contribute to the metastatic process. Here we will discuss the importance of E-M/CSC plasticity within malignant and pre-malignant populations of the tumor. Moreover, we will discuss how one may potentially target these populations, ultimately disrupting the metastatic cascade and increasing patient survival for those with mBC.

BMP9 overexpressing adipose-derived mesenchymal stem cells promote cartilage repair in osteoarthritis-affected knee joint via the Notch1/Jagged1 signaling pathway

Osteoarthritis (OS) is a common disease in orthopedics. Although OS is known as an inflammation mediated by inflammatory cytokines; however, the mechanism is poorly understood. In the present study, the role of bone morphogenetic protein-9 (BMP9) was investigated in chondrogenic differentiation of adipose-derived mesenchymal stem cells (ADMSCs). ADMSCs were transfected with BMP9. BMP9 mRNA expression was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Type II collagen and aggrecan expression was detected by western blotting and RT-qPCR. Mouse models of knee OS were established. Hematoxylin-eosin staining and toluidine blue staining were performed to observe changes in the OS-affected knee joint. After intra-articular injection of ADMSCs transfected with BMP9, intra-articular expression of type II collagen and aggrecan was detected by western blot analysis and RT-qPCR. After the Notch signaling pathway was inhibited in ADMSCs, ADMSCs were injected into the articular cavity. The expression of Notch signaling pathway-related proteins Notch1 and Jagged1 was detected by western blot analysis and RT-qPCR. BMP9 promoted chondrogenic differentiation of ADMSCs. After injection of BMP9 overexpressing ADMSCs into the articular space, type II collagen and aggrecan expression was increased. When the Notch signaling pathway of ADMSCs was inhibited, the ability of BMP9 overexpressing ADMSCs to repair the cartilage in the OS-affected knee joint was attenuated. These results demonstrate that upregulating BMP9 protein expression may promote the chondrogenic differentiation of ADMSCs. Intra-articular injection of ADMSCs contributes to cartilage repair in OS-affected knee joints through the Notch1/Jagged1 signaling pathway.

TIPE3 protein promotes breast cancer metastasis through activating AKT and NF-κB signaling pathways

TIPE3 (TNFAIP8L3) is the transfer protein of phosphoinositide second messengers that promote cancer. Its role in breast cancer has not been evaluated. We report here that TIPE3 protein was significantly upregulated in human breast cancer tissues as compared with adjacent non-tumor tissues from the same patients. The level of TIPE3 protein in invasive ductal carcinoma was significant higher than that in ductal carcinoma in situ (DCIS), and the level of TIPE3 in lymphatic metastasized carcinoma was higher than that in invasive ductal carcinoma from the same patients. Additionally, the level of TIPE3 protein was positively correlated with the level of human epidermal growth factor receptor 2 (HER-2), and TIPE3 expression was significantly higher in high-invasive breast cancer cell lines than that in low-invasive cell lines. Importantly, TIPE3 knockdown in breast cancer cells inhibited cell proliferation, migration, and invasion in vitro, whereas TIPE3 overexpression had the opposite effect. In mice, TIPE3 expression significantly promoted the metastasis of breast cancer cells. TIPE3 expression also increased the level of MMP2 and uPA, and the activation of the AKT and NF-κB signaling pathways. These results demonstrate that TIPE3 may promote breast cancer growth and metastasis through AKT and NF-κB, and may serve as a potential biomarker for breast cancer metastasis.

Differentiation-inducing therapeutic effect of Notch inhibition in reversing malignant transformation of liver normal stem cells via MET

BACKGROUND

Liver cancer stem cells (LCSCs) are the key factors for cancer metastasis, recurrent, and drug resistance. LCSCs are originated from either hepatocytes dedifferentiation or differentiation arresting of liver normal stem cells (LNSCs). Differentiation-inducing therapy is a novel strategy in solid tumors. Furthermore, Notch signaling pathway has been proved to play important role in the process of hepatocytes differentiation. In previous study, a malignant transformation cellular model of LNSCs has been built up, and in this study we are trying to illustrate whether inhibition of Notch can reverse this malignant tendency and drive these malignant cells back to differentiate into mature hepatocytes.

RESULTS

Inhibition of Notch signaling pathway can down-regulate the stemness-related cancer markers, lower the proliferative status, alleviate the invasive characteristic, or attenuate the metastasis tendency. What is more, it can help the malignantly transformed cells to regain the mature hepatic function of glucagon synthesis, urea metabolism, albumin production, and indocyanine-green (ICG) clearance.

MATERIALS AND METHODS

HOX transcript antisense RNA (HOTAIR) expression was enhanced in LNSCs via lentivirus transduction to set up the malignant transformation cellular model. Then, a Notch inhibitor was applied to induce malignantly transformed cells differentiate into mature hepatocytes, and malignant abilities of proliferation, invasiveness, tumorigenesis as well as mature hepatocyte function were observed and compared.

CONCLUSIONS

The data demonstrate that the anti-tumor effects of Notch inhibition may lie not only on killing the cancer cells or LCSCs directly, it can also induce the LCSCs differentiation into mature hepatocytes via mesenchymal-epithelial transition (MET) progress or downgrade the malignancy.

Cancer Stem Cell Hypothesis for Therapeutic Innovation in Clinical Oncology? Taking the Root Out, Not Chopping the Leaf

Clinical oncology is in need of therapeutic innovation. New hypotheses and concepts for translation of basic research to novel diagnostics and therapeutics are called for. In this context, the cancer stem cell (CSC) hypothesis rests on the premise that tumors comprise tumor cells and a subset of tumor-initiating cells, CSCs, in a quiescent state characterized by slow cell cycling and expression of specific stem cell surface markers with the capability to maintain a tumor in vivo. The CSCs have unlimited self-renewal abilities and propagate tumors through division into asymmetric daughter cells. This differentiation is induced by both genetic and environmental factors. Another characteristic of CSCs is their therapeutic resistance, which is due to their quiescent state and slow dividing. Notably, the CSC phenotype differs greatly between patients and different cancer types. The CSCs may differ genetically and phenotypically and may include primary CSCs and metastatic stem cells circulating within the blood system. Targeting CSCs will require the knowledge of distinct stem cells within the tumor. CSCs can differentiate into nontumorigenic cells and this has been touted as the source of heterogeneity observed in many solid tumors. The latter cannot be fully explained by epigenetic regulation or by the clonal evolution theory. This heterogeneity markedly influences how tumors respond to therapy and prognosis. The present expert review offers an analysis and synthesis of the latest research and concepts on CSCs, with a view to truly disruptive innovation for future diagnostics and therapeutics in clinical oncology.

Recent progress on the effects of microRNAs and natural products on tumor epithelial-mesenchymal transition

Epithelial–mesenchymal transition (EMT) is a biological process of phenotypic transition of epithelial cells that can promote physiological development as well as tissue healing and repair. In recent years, cancer researchers have noted that EMT is closely related to the occurrence and development of tumors. When tumor cells undergo EMT, they can develop enhanced migration and local tissue invasion abilities, which can lead to metastatic growth. Nevertheless, two researches in NATURE deny its necessity in specific tumors and that is discussed in this review. The degree of EMT and the detection of EMT-associated marker molecules can also be used to judge the risk of metastasis and to evaluate patients’ prognosis. MicroRNAs (miRNAs) are noncoding small RNAs, which can inhibit gene expression and protein translation through specific binding with the 3′ untranslated region of mRNA. In this review, we summarize the miRNAs that are reported to influence EMT through transcription factors such as ZEB, SNAIL, and TWIST, as well as some natural products that regulate EMT in tumors. Moreover, mutual inhibition occurs between some transcription factors and miRNAs, and these effects appear to occur in a complex regulatory network. Thus, understanding the role of miRNAs in EMT and tumor growth may lead to new treatments for malignancies. Natural products can also be combined with conventional chemotherapy to enhance curative effects.

Upregulation of ATG4A promotes osteosarcoma cell epithelial-to-mesenchymal transition through the Notch signaling pathway

Osteosarcoma is a malignant tumor in children and adolescents. Previous studies showed that ATG4A is an autophagy-related gene involved in cancers. In this study, we aimed to identify the biological role of ATG4A in osteosarcoma. The expression levels of ATG4A were analyzed in osteosarcoma tissues by using reverse transcription-quantitative polymerase chain reaction (qRT-PCR) and western blotting. ATG4A was knocked-down or overexpressed in SAOS2 and HOS cell lines by transfection. Cell counting kit-8 (CCK-8) and clone formation assay were used to assess the effects of ATG4A on cell proliferation. Wound healing and Transwell assays were performed to evaluate the effects of ATG4A on cell migration and invasion, respectively. Epithelial-mesenchymal transition (EMT) markers and Notch signaling pathway targeting molecules were examined by western blotting. The results indicated that ATG4A was up-regulated in osteosarcoma tissues. In SAOS2 cells, knockdown of ATG4A inhibited the proliferation, migration and invasion, up-regulated the expression of E-cadherin and down-regulated the expression of vimentin, Notch1 and Hes1. In HOS cells, overexpression of ATG4A promoted the proliferation, migration and invasion, up-regulated the expression of vimentin, Notch1 and Hes1 and down-regulated the expression of E-cadherin. In conclusion, these findings demonstrate that ATG4A is up-regulated in osteosarcoma tissues. In osteosarcoma cells, ATG4A promotes the EMT process partly by the Notch signaling pathway. These results suggest that ATG4A might represent a potential therapeutic target for patients with osteosarcoma.

CLDN-1 promoted the epithelial to migration and mesenchymal transition (EMT) in human bronchial epithelial cells via Notch pathway

Claudin-1 (CLDN-1) is one of main tight junction components that play an important role in epithelial-mesenchymal transition (EMT). However, the effects of CLDN-1 on the migration and EMT induced by TGF-β1 in primary normal human bronchial epithelial (NHBE) and BEAS-2B cells have not been clear. The expression of CLDN-1 was quantified by Western blotting in NHBE and BEAS-2B cells. Cell migration and invasion were detected using transwell assays. The expression level of E-cadherin, N-cadherin, α-SMA, and Vimentin was evaluated by quantitative real-time PCR and Western blotting. Here we showed that the protein expression of CLDN-1 was increased exposed to TGF-β1 in a dose- and time-dependent manner. Knockdown of CLDN-1 using small interfering CLDN-1 RNA (siCLDN-1) prevented the migration and invasion in NHBE and BEAS-2B cells. Moreover, depletion of CLDN-1 promoted the E-cadherin expression and decreased the mRNA and protein levels of N-cadherin, α-SMA, and Vimentin induced by TGF-β1. Furthermore, CLDN-1 silencing resulted in the reduction of the Notch intracellular domain (NICD) and hairy enhancer of split-1 (Hes-1) in mRNA and protein level. Jagged-1, an activator of Notch signaling pathway, abrogated the protective function of siCLDN-1 in migration and EMT. In conclusion, CLDN-1 promoted the migration and EMT through the Notch signaling pathway.

Cinobufagin induces apoptosis of osteosarcoma cells through inactivation of Notch signaling

Osteosarcoma (OS) is a major cause of cancer-related mortality in children and young adults worldwide. Due to preexisting or acquired chemoresistance, the current standard neoadjuvant chemotherapy regimens show only moderate activity against OS. In the current study, we explored the potential anti-OS Cinobufagin in vitro and in vivo, and investigated its underlying mechanisms. The antitumor potential of Cinobufagin was assessed using cell viability assays, and cycle and apoptosis were determined. In a cell-based assay, the mRNA and protein expression of Notch-1, Hes-1, Hes-5 and Hey-1 were determined by quantitative polymerase chain reactions and western blotting. The involvement of Notch signaling in Cinobufagin-induced apoptosis was confirmed using gain and loss-of function assays. A xenograft OS model was established and the antitumor effect and biosafety of Cinobufagin were evaluated. Cinobufagin suppressed OS cells growth in a dose- and time-dependent manner, involving both cell cycle arrest at the S phase and programmed cell death. Cinobufagin treatment decreased the expression of Notch-1, and Hes-1, Hes-5 and Hey-1 gene expression in OS cell lines. Furthermore, Notch activation attenuated the Cinobufagin-induced apoptosis, while Notch inhibition enhanced this effect. Using a mouse xenograft model, we found that Cinobufagin inhibited OS cell growth in vivo. The mice showed excellent tolerance to Cinobufagin treatment. Taken together, our data suggested that Cinobufagin inhibited cell survival and induced apoptosis in OS cells both in vitro and in vivo, and these effects were partly mediated through the Notch pathway.