Signalling mechanism(s) of epithelial-mesenchymal transition and cancer stem cells in tumour therapeutic resistance

Advancements in a novel model of autophagy and immune network regulation in radioresistance of cancer stem cells

Radiotherapy, a precise modality for treating malignant tumors, has undergone rapid advancements in primary and clinical research. The mechanisms underlying tumor radioresistance have become significant research. With the introduction and in-depth study of cancer stem cells (CSCs) theory, CSCs have been identified as the primary factor contributing to the development of tumor radioresistance. The "stemness" of CSCs is a biological characteristic of a small subset of cells within tumor tissues, characterized by self-renewal solid ability. This characteristic leads to resistance to radiotherapy, chemotherapy, and targeted therapies, driving tumor recurrence and metastasis. Another study revealed that cellular autophagy plays a pivotal role in maintaining the "stemness" of CSCs. Autophagy is a cellular mechanism that degrades proteins and organelles to generate nutrients and energy in response to stress. This process maintains cellular homeostasis and contributes to CSCs radioresistance. Furthermore, ionizing radiation (IR) facilitates epithelial-to-mesenchymal transition (EMT), vascular regeneration, and other tumor processes by influencing the infiltration of M2-type tumor-associated macrophages (TAMs). IR promotes the activation of the classical immunosuppressive "switch," PD-1/PD-L1, which diminishes T-cell secretion, leading to immune evasion and promoting radioresistance. Interestingly, recent studies have found that the immune pathway PD-1/PD-L1 is closely related to cellular autophagy. However, the interrelationships between immunity, autophagy, and radioresistance of CSCs and the regulatory mechanisms involved remain unclear. Consequently, this paper reviews recent research to summarize these potential connections, aiming to establish a theoretical foundation for future studies and propose a new model for the network regulation of immunity, autophagy, and radioresistance of tumor cells.

Mangiferin: A natural bioactive immunomodulating glucosylxanthone with potential against cancer and rheumatoid arthritis

Mangiferin is a naturally occurring glucosylxanthone that has shown promising immunomodulatory effects. It is generally isolated from the leaves, peels, bark, and kernels of Mangifera indica Linn. Mangiferin is like a miraculous natural bioactive molecule that has an immunomodulatory function that makes it a potential therapeutic candidate for the treatment of rheumatoid arthritis (RA) and cancer. The anticancer activity of mangiferin acts by blocking NF-κB, as well as regulating the β-catenin, EMT, MMP9, MMP2, LDH, ROS, and NO, and also by the activation of macrophages. It has no cytotoxic effect on grown chondrocytes and lowers matrix metalloproteinase levels. Additionally, it has a potent proapoptotic impact on synoviocytes. The precise molecular mechanism of action of mangiferin on RA and malignancies is still unknown. This comprehensive review elaborates on the immunomodulatory effect of mangiferin and its anticancer and anti-RA activity. This also explained the total synthesis of mangiferin and its in vitro and in vivo screening models.

Tumor-associated macrophages in anti-PD-1/PD-L1 immunotherapy for hepatocellular carcinoma: recent research progress

Hepatocellular carcinoma (HCC) is one of the cancers that seriously threaten human health. Immunotherapy serves as the mainstay of treatment for HCC patients by targeting the programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) axis. However, the effectiveness of anti-PD-1/PD-L1 treatment is limited when HCC becomes drug-resistant. Tumor-associated macrophages (TAMs) are an important factor in the negative regulation of PD-1 antibody targeted therapy in the tumor microenvironment (TME). Therefore, as an emerging direction in cancer immunotherapy research for the treatment of HCC, it is crucial to elucidate the correlations and mechanisms between TAMs and PD-1/PD-L1-mediated immune tolerance. This paper summarizes the effects of TAMs on the pathogenesis and progression of HCC and their impact on HCC anti-PD-1/PD-L1 immunotherapy, and further explores current potential therapeutic strategies that target TAMs in HCC, including eliminating TAMs in the TME, inhibiting TAMs recruitment to tumors and functionally repolarizing M2-TAMs (tumor-supportive) to M1-TAMs (antitumor type).

Evaluation of BMP-2 as a Differentiating and Radiosensitizing Agent for Colorectal Cancer Stem Cells

BACKGROUND

Despite effective clinical responses, a large proportion of patients undergo resistance to radiotherapy. The low response rate to current treatments in different stages of colorectal cancer depends on the prominent role of stem cells in cancer.

OBJECTIVE

In the present study, the role of BMP-2 as an ionizing radiation-sensitive factor in colorectal cancer cells was investigated.

METHODS

A sphere formation assay was used for the enrichment of HCT-116 cancer stem cells (CSCs). The effects of combination therapy (BMP-2+ radiation) on DNA damage response (DDR), proliferation, and apoptosis were evaluated in HCT-116 and CSCs. Gene expressions of CSCs and epithelialmesenchymal transition (EMT) markers were also evaluated.

RESULTS

We found that the sphere formation assay showed a significant increase in the percentage of CSCs. Moreover, expression of CSCs markers, EMT-related genes, and DNA repair proteins significantly decreased in HCT-116 cells compared to the CSCs group after radiation. In addition, BMP-2 promoted the radiosensitivity of HCT-116 cells by decreasing the survival rate of the treated cells at 2, 4, and 6 Gy compared to the control group in HCT-116 cells.

CONCLUSION

Our findings indicated that BMP-2 could affect numerous signaling pathways involved in radioresistance. Therefore, BMP-2 can be considered an appealing therapeutic target for the treatment of radioresistant human colorectal cancer.

Signal Pathways and microRNAs in Osteosarcoma Growth and the Dual Role of Mesenchymal Stem Cells in Oncogenesis

The major challenges in Osteosarcoma (OS) therapy are its heterogeneity and drug resistance. The development of new therapeutic approaches to overcome the major growth mechanisms of OS is urgently needed. The search for specific molecular targets and promising innovative approaches in OS therapy, including drug delivery methods, is an urgent problem. Modern regenerative medicine focuses on harnessing the potential of mesenchymal stem cells (MSCs) because they have low immunogenicity. MSCs are important cells that have received considerable attention in cancer research. Currently, new cell-based methods for using MSCs in medicine are being actively investigated and tested, especially as carriers for chemotherapeutics, nanoparticles, and photosensitizers. However, despite the inexhaustible regenerative potential and known anticancer properties of MSCs, they may trigger the development and progression of bone tumors. A better understanding of the complex cellular and molecular mechanisms of OS pathogenesis is essential to identify novel molecular effectors involved in oncogenesis. The current review focuses on signaling pathways and miRNAs involved in the development of OS and describes the role of MSCs in oncogenesis and their potential for antitumor cell-based therapy.

Chlorogenic Acid Inhibits Epithelial-Mesenchymal Transition and Invasion of Breast Cancer by Down-Regulating LRP6

Epithelial-mesenchymal transition (EMT) is a crucial biologic process for breast cancer metastasis, and inhibition of EMT could be an effective approach to suppress metastatic potential of mammary cancer. High expression of low-density lipoprotein receptor-related protein 6 (LRP6) is usually observed in breast carcinoma and predicts poor prognosis. In the present study, we investigated whether chlorogenic acid (CA) can inhibit the EMT of breast cancer cells and underlying molecular mechanism. We found that CA treatment transformed MCF-7 cell morphology from spindle shape (mesenchymal phenotype) to spherical shape (epithelial phenotype). CA clearly increased epithelial biomarkers' expression (E-cadherin and ZO-1) but decreased mesenchymal proteins' expression (ZEB1, N-cadherin, vimentin, snail, and slug). In addition, CA attenuated MMP-2 and MMP-9 activities and inhibited cell migration and invasion. CA downregulated the expression of LRP6 in MCF-7 cells. Knockdown LRP6 with siRNA repressed cell mobility and invasion, wheras overexpression of LRP6 promoted EMT and antagonized the EMT inhibitory effect of CA on MCF-7 cells. Furthermore, CA directly interacted with Wnt/β-catenin signaling coreceptor LRP6 and reduced LRP6, p-LRP6, and β-catenin expression levels in MCF-7 cells. In vivo study revealed that CA notably reduced tumor volume and tumor weight. CA decreased the expression of LRP6, N-cadherin, ZEB1, vimentin, MMP2, MMP9, and increased the expression of E-cadherin and ZO-1. In conclusion, CA inhibited EMT and invasion of breast cancer by targeting LRP6. SIGNIFICANCE STATEMENT: CA, the familiar polyphenol compound in traditional Chinese medicine, repressed EMT and weakened cellular mobility and invasion in MCF-7 cells. The mechanism studies demonstrated that CA could inhibit EMT and invasion of MCF-7 cells via targeting LRP6. Additionally, CA restrained tumor growth and xenograft tumor EMT in vivo. The EMT inhibitory property of CA warrants further studies of CA as a drug candidate for the therapy of metastatic breast carcinoma.

Apigenin in cancer therapy: Prevention of genomic instability and anticancer mechanisms

The incidence of cancer has been growing worldwide. Better survival rates following the administration of novel drugs and new combination therapies may concomitantly cause concern regarding the long-term adverse effects of cancer therapy, for example, second primary malignancies. Moreover, overcoming tumour resistance to anticancer agents has been long considered as a critical challenge in cancer research. Some low toxic adjuvants such as herb-derived molecules may be of interest for chemoprevention and overcoming the resistance of malignancies to cancer therapy. Apigenin is a plant-derived molecule with attractive properties for chemoprevention, for instance, promising anti-tumour effects, which may make it a desirable adjuvant to reduce genomic instability and the risks of second malignancies among normal tissues. Moreover, it may improve the efficiency of anticancer modalities. This paper aims to review various effects of apigenin in both normal tissues and malignancies. In addition, we explain how apigenin may have the ability to protect usual cells against the genotoxic repercussions following radiotherapy and chemotherapy. Furthermore, the inhibitory effects of apigenin on tumours will be discussed.

Effects of 5-ALA mediated photodynamic therapy in oral cancer stem cells

The aim of the present study was to investigate the effects of PDT using the photosensitizer 5-aminoulevulinic acid (5-ALA) in oral squamous cell carcinoma (OSCC) behavior, mainly regarding its role on the cancer stem cell (CSC) phenotypes and in maintenance of the stem cell properties. Two OSCC cell lines were used and divided in the groups: Control, 5-ALA, LED 6 J/cm² and PDT. MTT and Neutral red assays were used to access cellular viability, cell migration was evaluated by the wound healing assay. The stem cell phenotype was analyzed by flow cytometry to evaluate the CD44^high/ESA^high, CD44^high/ESA^low and CD44^low populations, by the clonogenic and tumor sphere formation assays as well as by RT-qPCR. The presence of Protoporphyrin IX in each CSC fraction was evaluated by flow cytometry. The OSCC cell lines showed a significant decrease in cell viability and migration after PDT. The percentage of CD44^high/ESA^high cells decreased after PDT, which was associated with an increase in the CD44^low cells and with a functional decrease in the colony and sphere formation capacity. CD44^high/ESA^high cells showed increased PpIX, which contributed for their greater sensitivity to PDT. INV gene increased significantly after PDT, indicating cellular differentiation. Altogether, our results demonstrate that 5-ALA mediated PDT decreases not only the fraction of oral CSC but also their functional capabilities, inducing their differentiation.

Mechanistic Interrogation of Cell Transformation In Vitro: The Transformics Assay as an Exemplar of Oncotransformation

The Transformics Assay is an in vitro test which combines the BALB/c 3T3 Cell Transformation Assay (CTA) with microarray transcriptomics. It has been shown to improve upon the mechanistic understanding of the CTA, helping to identify mechanisms of action leading to chemical-induced transformation thanks to RNA extractions in specific time points along the process of in vitro transformation. In this study, the lowest transforming concentration of the carcinogenic benzo(a)pyrene (B(a)P) has been tested in order to find molecular signatures of initial events relevant for oncotransformation. Application of Enrichment Analysis (Metacore) to the analyses of the results facilitated key biological interpretations. After 72 h of exposure, as a consequence of the molecular initiating event of aryl hydrocarbon receptor (AhR) activation, there is a cascade of cellular events and microenvironment modification, and the immune and inflammatory responses are the main processes involved in cell response. Furthermore, pathways and processes related to cell cycle regulation, cytoskeletal adhesion and remodeling processes, cell differentiation and transformation were observed.

Herb and Spices in Colorectal Cancer Prevention and Treatment: A Narrative Review

Colorectal cancer (CRC) is the second most deadly cancer worldwide. CRC management is challenging due to late detection, high recurrence rate, and multi-drug resistance. Herbs and spices used in cooking, practised for generations, have been shown to contain CRC protective effect or even be useful as an anti-CRC adjuvant therapy when used in high doses. Herbs and spices contain many bioactive compounds and possess many beneficial health effects. The chemopreventive properties of these herbs and spices are mainly mediated by the BCL-2, K-ras, and MMP pathways, caspase activation, the extrinsic apoptotic pathway, and the regulation of ER-stress-induced apoptosis. As a safer natural alternative, these herbs and spices could be good candidates for chemopreventive or chemotherapeutic agents for CRC management because of their antiproliferative action on colorectal carcinoma cells and inhibitory activity on angiogenesis. Therefore, in this narrative review, six different spices and herbs: ginger (Zingiber officinale Roscoe), turmeric (Curcuma longa L.), garlic (Allium sativum L.), fenugreek (Trigonella foenum-graecum L.), sesame (Sesamum indicum L.), and flaxseed (Linum usitatissimum L.) used in daily cuisine were selected for this study and analyzed for their chemoprotective or chemotherapeutic roles in CRC management with underlying molecular mechanisms of actions. Initially, this study comprehensively discussed the molecular basis of CRC development, followed by culinary and traditional uses, current scientific research, and publications of selected herbs and spices on cancers. Lead compounds have been discussed comprehensively for each herb and spice, including anti-CRC phytoconstituents, antioxidant activities, anti-inflammatory properties, and finally, anti-CRC effects with treatment mechanisms. Future possible works have been suggested where applicable.

Parathyroid Hormone-Related Protein Inhibition Blocks Triple-Negative Breast Cancer Expansion in Bone Through Epithelial to Mesenchymal Transition Reversal

Parathyroid hormone-related protein (PTHrP) plays a major role in skeletal metastasis but its action mechanism has not been fully defined. We previously demonstrated the crucial importance of PTHrP in promoting mammary tumor initiation, growth, and metastasis in a mouse model with a mammary epithelium-targeted Pthlh gene ablation. We demonstrate here a novel mechanism for bone invasion involving PTHrP induction of epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs) regulation. Clustered regularly interspaced short palindromic repeats (CRISPR)-mediated Pthlh gene ablation was used to study EMT markers, phenotype, and invasiveness in two triple-negative breast cancer (TNBC) cell types (established MDA-MB-231 and patient-derived PT-TNBC cells). In vitro, Pthlh ablation in TNBC cells reduced EMT markers, mammosphere-forming ability, and CD44high/CD24low cells ratio. In vivo, cells were injected intratibially into athymic nude mice, and therapeutic treatment with our anti-PTHrP blocking antibody was started 2 weeks after skeletal tumors were established. In vivo, compared to control, lytic bone lesion from Pthlh -ablated cells decreased significantly over 2 weeks by 27% for MDA-MB-231 and by 75% for PT-TNBC-injected mice (p < 0.001). Micro-CT (μCT) analyses also showed that antibody therapy reduced bone lytic volume loss by 52% and 48% for non-ablated MDA-MB-231 and PT-TNBC, respectively (p < 0.05). Antibody therapy reduced skeletal tumor burden by 45% and 87% for non-ablated MDA-MB-231 and PT-TNBC, respectively (p < 0.002) and caused a significant decrease of CSC/EMT markers ALDH1, vimentin, and Slug, and an increase in E-cadherin in bone lesions. We conclude that PTHrP is a targetable EMT molecular driver and suggest that its pharmacological blockade can provide a potential therapeutic approach against established TNBC-derived skeletal lesions. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Anticancer Properties of Curcumin Against Colorectal Cancer: A Review

Colorectal cancer (CRC) is one of the most common and reoccurring diseases, as well as the world’s second largest cause of mortality. Despite existing preventative, diagnostic, and treatment methods, such as chemotherapy, the number of instances rises year after year. As a result, new effective medications targeting specific checkpoints should be developed to combat CRC. Natural compounds, such as curcumin, have shown significant anti-colorectal cancer characteristics among medications that can be used to treat CRC. These chemicals are phenolic compounds that belong to the curcuminoids category. Curcumin exerts its anti-proliferative properties against CRC cell lines in vitro and in vivo via a variety of mechanisms, including the suppression of intrinsic and extrinsic apoptotic signaling pathways, the stoppage of the cell cycle, and the activation of autophagy. Curcumin also has anti-angiogenesis properties. Thus, this review is aimed at emphasizing the biological effect and mode of action of curcumin on CRC. Furthermore, the critical role of these substances in CRC chemoprevention was emphasized.

Acquired chemoresistance can lead to increased resistance of pancreatic cancer cells to oncolytic vesicular stomatitis virus

Vesicular stomatitis virus (VSV) is a promising oncolytic virus (OV) against different malignancies, including pancreatic ductal adenocarcinoma (PDAC). Our previous studies have demonstrated that VSV-based OVs are effective against the majority of tested human PDAC cell lines. However, some PDAC cell lines are resistant to VSV. PDAC is one of the deadliest types of human malignancies in part due to intrinsic or acquired chemoresistance. Here, we investigated how acquired chemoresistance impacts the efficacy of VSV-based OV therapy. Using an experimental evolution approach, we generated PDAC cell lines with increased resistance to gemcitabine and examined their responsiveness to oncolytic virotherapy. We found that gemcitabine-resistant PDAC cells become more resistant to VSV. The cross-resistance correlated with upregulated levels of a subset of interferon-stimulated genes, resembling the interferon-related DNA damage resistance signature (IRDS), often associated with resistance of cancer cells to chemotherapy and/or radiation therapy. Analysis of ten different PDAC cell lines showed that four PDAC cell lines most resistant to VSV were also highly resistant to gemcitabine, and they all displayed IRDS-like expression in our previous reports. Our study highlights a possible interaction between two different therapies that should be considered in the future for the development of rational treatment regimens.

The various regulatory functions of long noncoding RNAs in apoptosis, cell cycle, and cellular senescence

Long noncoding RNAs (lncRNAs) are a group of noncoding cellular RNAs involved in significant biological phenomena such as differentiation, cell development, genomic imprinting, adjusting the enzymatic activity, regulating chromosome conformation, apoptosis, cell cycle, and cellular senescence. The misregulation of lncRNAs interrupting normal biological processes has been implicated in tumor formation and metastasis, resulting in cancer. Apoptosis and cell cycle, two main biological phenomena, are highly conserved and intimately coupled mechanisms. Hence, some cell cycle regulators can influence both programmed cell death and cell division. Apoptosis eliminates defective and unwanted cells, and the cell cycle enables cells to replicate themselves. The improper regulation of apoptosis and cell cycle contributes to numerous disorders such as neurodegenerative and autoimmune diseases, viral infection, anemia, and mainly cancer. Cellular senescence is a tumor-suppressing response initiated by environmental and internal stress factors. This phenomenon has recently attained more attention due to its therapeutic implications in the field of senotherapy. In this review, the regulatory roles of lncRNAs on apoptosis, cell cycle, and senescence will be discussed. First, the role of lncRNAs in mitochondrial dynamics and apoptosis is addressed. Next, the interaction between lncRNAs and caspases, pro/antiapoptotic proteins, and also EGFR/PI3K/PTEN/AKT/mTORC1 signaling pathway will be investigated. Furthermore, the effect of lncRNAs in the cell cycle is surveyed through interaction with cyclins, cdks, p21, and wnt/β-catenin/c-myc pathway. Finally, the function of essential lncRNAs in cellular senescence is mentioned.

Identification of a Four-Gene-Based SERM Signature for Prognostic and Drug Sensitivity Prediction in Gastric Cancer

Background

Gastric cancer (GC) is a highly molecular heterogeneous tumor with poor prognosis. Epithelial-mesenchymal transition (EMT) process and cancer stem cells (CSCs) are reported to share common signaling pathways and cause poor prognosis in GC. Considering about the close relationship between these two processes, we aimed to establish a gene signature based on both processes to achieve better prognostic prediction in GC.

Methods

The gene signature was constructed by univariate Cox and the least absolute shrinkage and selection operator (LASSO) Cox regression analyses by using The Cancer Genome Atlas (TCGA) GC cohort. We performed enrichment analyses to explore the potential mechanisms of the gene signature. Kaplan-Meier analysis and time-dependent receiver operating characteristic (ROC) curves were implemented to assess its prognostic value in TCGA cohort. The prognostic value of gene signature on overall survival (OS), disease-free survival (DFS), and drug sensitivity was validated in different cohorts. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) validation of the prognostic value of gene signature for OS and DFS prediction was performed in the Fudan cohort.

Results

A prognostic signature including SERPINE1, EDIL3, RGS4, and MATN3 (SERM signature) was constructed to predict OS, DFS, and drug sensitivity in GC. Enrichment analyses illustrated that the gene signature has tight connection with the CSC and EMT processes in GC. Patients were divided into two groups based on the risk score obtained from the formula. The Kaplan-Meier analyses indicated high-risk group yielded significantly poor prognosis compared with low-risk group. Pearson’s correlation analysis indicated that the risk score was positively correlated with carboplatin and 5-fluorouracil IC50 of GC cell lines. Multivariate Cox regression analyses showed that the gene signature was an independent prognostic factor for predicting GC patients’ OS, DFS, and susceptibility to adjuvant chemotherapy.

Conclusions

Our SERM prognostic signature is of great value for OS, DFS, and drug sensitivity prediction in GC, which may give guidance to the development of targeted therapy for CSC- and EMT-related gene in the future.

Sanguisorba officinalis L. suppresses 5-fluorouracil-sensitive and-resistant colorectal cancer growth and metastasis via inhibition of the Wnt/β-catenin pathway

BACKGROUND

Colorectal cancer (CRC) is a widespread cancer with high morbidity and mortality. Chemoresistance and metastasis are the current challenges for CRC treatment. Sanguisorba officinalis Linn. (called DiYu in Chinese, DY) is a traditional Chinese medicine (TCM) whose root is long used as medicinal part. In our previous study, the aqueous extract of DY could inhibit the Wnt/β-catenin pathway and showed great antitumor effect against CRC. The Wnt/β-catenin pathway is involved in CRC chemoresistance and metastasis. However, there is little study on the antitumor and antimetastatic effects of DY on resistant CRC cells. The aim of this study is to explore the effect of aqueous extract of DY on the growth and metastasis of 5-fluorouracil (5-FU) sensitive and resistant CRC, and to elucidate the underlying molecular mechanism.

METHODOLOGY

In this study, cell viability, cell colony formation and apoptosis analyses were performed to verify the in vitro antitumor effect of DY on 5-FU-sensitive and -resistant CRC cells. Next, transwell assays were used to test the inhibition activity of DY on CRC migration and invasion. Western Blotting assays were carried out to identify the molecular mechanism underlying the efficacy of DY extract. Xenograft CRC nude mice model and tumor metastasis model were used to confirm the in vivo antitumor and antimetastatic effects of DY.

RESULTS

DY inhibited cell proliferation and apoptosis via the upregulation of Bax, cleaved-caspase3 and cleaved-PARP proteins and downregulation of Bcl-2 protein. DY also inhibited cell migration and invasion via the downregulation of N-cadherin, vimentin and snail proteins and upregulation of E-cadherin protein, demonstrating that DY suppressed cell metastasis by reversing epithelial-to-mesenchymal transition (EMT) procession. Moreover, the protein expression levels of β-catenin in whole cell, cytoplasm and nucleus were decreased after DY treatment. Taken together, DY suppressed CRC cell growth and metastasis via inhibition of the Wnt pathway. Additionally, DY also demonstrated effective antitumor and anti-metastasis activities in vivo.

CONCLUSIONS

In conclusion, DY suppressed the growth and metastasis of 5-FU-sensitive and -resistant CRC via inhibition of the Wnt pathway, which indicated that DY could be a potential drug to treat CRC patients and improve clinic outcome.

Inhibition of the notch signaling pathway overcomes resistance of cervical cancer cells to paclitaxel through retardation of the epithelial-mesenchymal transition process

Use of paclitaxel as monotherapy or in combination with other therapeutic agents is a widely employed front-line chemotherapeutic strategy for cervical cancer. However, previous reports have shown that approximately 70% of the patients with cervical cancer develop resistance to paclitaxel. Epithelial-mesenchymal transition (EMT) contributes to the occurrence of chemoresistance in several types of cancer, including cervical cancer. Identification of the critical signaling pathway that regulates the EMT process may provide a novel strategy for avoiding or delaying the emergence of paclitaxel resistance during the treatment of cervical cancer. Herein, we established a paclitaxel-resistant cervical cancer cell line (HeLa-229PTR cells) by culturing parental HeLa-229 cells with increasing concentrations of paclitaxel. We observed elevated expression of Notch1 in HeLa-229PTR cells compared with their parental HeLa-229 cells, indicating its potential involvement in the EMT phenotype of the paclitaxel-resistant cells. Furthermore, silencing of the NOTCH1 gene, as well as treatment with a γ-secretase inhibitor (DAPT) partially reversed the EMT phenotype and significantly enhanced the sensitivity of HeLa-229PTR cells to paclitaxel. Moreover, we found that DAPT could significantly inhibit invasiveness, reduce colony formation activity, and promote apoptosis of HeLa-229PTR cells. Taken together, these results indicated that HeLa-229PTR cells develop the EMT phenotype partly through activation of Notch1 signaling. Thus, inhibition of Notch1 signaling can be a strategy for the reversal of the EMT phenotype and may increase the sensitivity of cervical cancer cells to treatment with paclitaxel.

Phenotypic changes on central nervous system (CNS) tumor cell lines cultured in vitro 2D and 3D models and treated with cisplatin

Despite aggressive therapy, most patients with brain tumors present disease relapse due to the cellular and molecular nature of these tumors. One of the models that best explains the heterogeneity observed in CNS tumors is the presence of cancer stem cells (CSCs). In this paper, we evaluated platinum-based response in brain tumor U-87 MG, LN-18, and KELLY cell lines cultured in monolayer (2D) and neurosphere (CSC enrichment- 3D) models. We evaluated mRNA expression of heat shock proteins (HSPA1A, HSPB1, HSPA1AL, TRAP1, and HSPD1), and DNA repair gene ERCC1. Changes in cell cycle and glycosylation profile were assessed by flow cytometry. After treatment with cisplatin, we found that the mRNA expression of HSPs markedly increased in the U-87 MG and LN-18 neurosphere cells. In KELLY monolayer cells, cisplatin induced upregulation of all genes. In KELLY neurosphere cells, only the HSPA1A, HSPB1, TRAP1, and HSPD1 genes were upregulated. The proportion of cells in the G₀/G₁ phase was significantly higher in U-87 MG neurosphere cisplatin-treated cells. A trend towards a greater proportion of cells in the S phase of U-87 MG monolayer cisplatin-treated cells was also observed. On the other hand, a significant decrease in the number of cells in the S phase and an increase in G₂/M was observed in LN-18 monolayer cisplatin-treated cells. Glycosylation analysis using lectins showed a higher surface binding for PNA in the U-87 MG treated monolayer and a lower binding for Concanavalin A in the treated neurospheres. The binding of Isolectin GS-IB4, GSII, and SBA in KELLY monolayer cisplatin-treated cells was lower whereas the proportion of cells labeled with Concanavalin A was higher. In the KELLY neurosphere cisplatin-treated cells, the binding of Concanavalin A was lower than nontreated cells. Thus, our findings strongly supported the idea that definitions of phenotypic characteristics may help to establish better therapeutic strategies for brain tumors.

MicroRNA‑8063 targets heterogeneous nuclear ribonucleoprotein AB to inhibit the self‑renewal of colorectal cancer stem cells via the Wnt/β‑catenin pathway

The presence of cancer stem cells (CSCs) is a major cause of therapeutic failure in a variety of cancer types, including colorectal cancer (CRC). However, the underlying mechanisms that regulate the self-renewal of colorectal cancer stem cells (CRCSCs) remain unclear. Our previous study utilized CRCSCs and their parent cells; through gene microarray screening and bioinformatics analysis, we hypothesized that microRNA (miR)-8063 may bind to, and regulate the expression of, heterogeneous nuclear ribonucleoprotein AB (hnRNPAB) to facilitate the regulation of CRCSC self-renewal. The aim of the present study was to confirm this conjecture through relevant experiments. The results indicated that compared with that in parent cells, miR-8063 expression was significantly downregulated in CRCSCs, while hnRNPAB expression was increased. Furthermore, hnRNPAB was identified as a direct target of miR-8063 using a dual-Luciferase assay. Overexpression of hnRNPAB promoted the acquisition of CSC characteristics in CRC cells (increased colony formation ability, enhanced tumorigenicity, and upregulated expression of CSC markers), as well as the upregulation of key proteins (Wnt3a, Wnt5a and β-catenin) in the Wnt/β-catenin signaling pathway. Similarly, after silencing miR-8063 in CRC cells, the characteristics of CSC were altered, and the expression of hnRNPAB protein was promoted. However, post overexpression of miR-8063 in CRCSCs, the self-renewal ability of CSCs was weakened with the downregulation of hnRNPAB protein, Wnt3a, Wnt5a and β-catenin. These results suggest that as a tumor suppressor, miR-8063 is involved in regulating the self-renewal of CRCSCs, where loss of miR-8063 expression weakens its inhibition on hnRNPAB, which leads to the activation of Wnt/β-catenin signaling to promote the self-renewal of CRCSCs.

miR-451 suppresses EMT and metastasis in glioma cells

The metastasis of tumor cells is a challenge for the clinical treatment of glioma. Epithelial-mesenchymal transition (EMT) contributes to glioma cell invasiveness. Our previous study confirmed that the expression of miRNA-451, which inhibits the PI3K/Akt signaling pathway by directly targeting CAB39 and plays a repressive role in glioma, is downregulated in glioma. However, the specific mechanism of miRNA-451 regulation in glioma is unclear. In this study, we investigated whether miRNA-451 blocks the processes of EMT and metastasis in glioma cells in vivo and in vitro. By targeting CAB39, miRNA-451 likely triggers the PI3K/Akt/Snail signaling pathway to reduce glioma proliferation, invasion, migration and EMT. We used Western blotting experiments to demonstrate that overexpression of miRNA-451 significantly reduced p-AKT(Ser473), N-cadherin, Vimentin, Twist, Snail and Cyclin D1 expression and increased E-cadherin expression. We demonstrated that overexpression of miR-451 suppressed glioma cell proliferation, invasion, migration and EMT by MTT and colony formation assays, Transwell assays, wound healing assays and animal experiments. Taken together, these results suggest that miRNA-451 can reduce EMT and metastasis in glioma cells through the suppression of the PI3K/Akt/Snail signaling pathway by targeting CAB39 in vitro and in vivo. miR-451 may be a new target for glioma treatment.

Vitamin D Regulates CXCL12/CXCR4 and Epithelial-to-Mesenchymal Transition in a Model of Breast Cancer Metastasis to Lung

Vitamin D deficiency is associated with poor cancer outcome in humans, and administration of vitamin D or its analogs decreases tumor progression and metastasis in animal models. Using the mouse mammary tumor virus-polyoma middle T antigen (MMTV-PyMT) model of mammary cancer, we previously demonstrated a significant acceleration of carcinogenesis in animals on a low vitamin D diet and a reduction in spontaneous lung metastases when mice received vitamin D through perfusion. We investigate here the action mechanism for vitamin D in lung metastasis in the same non-immunodeficient model and demonstrate that it involves the control of epithelial to mesenchymal transition as well as interactions between chemokine C-X-C motif chemokine 12 (CXCL12) and its receptor C-X-C chemokine receptor type 4 (CXCR4). In vitro, 10-9M vitamin D treatment modifies the phenotype of MMTV-PyMT primary mammary tumor cells and significantly decreases their invasiveness and mammosphere formation capacity by 40% and 50%, respectively. Vitamin D treatment also inhibits phospho-signal transducer and activator of transcription 3 (p-STAT3), zinc finger E-box-binding homeobox 1 (Zeb1), and vimentin by 52%, 75%, and 77%, respectively, and increases E-cadherin by 87%. In vivo, dietary vitamin D deficiency maintains high levels of Zeb1 and p-STAT3 in cells from primary mammary tumors and increases CXCL12 expression in lung stroma by 64%. In lung metastases, vitamin D deficiency increases CXCL12/CXCR4 co-localization by a factor of 2.5. These findings indicate an involvement of vitamin D in mammary cancer "seed" (primary tumor cell) and "soil" (metastatic site) and link vitamin D deficiency to epithelial-to-mesenchymal transition (EMT), CXCL12/CXCR4 signaling, and accelerated metastasis, suggesting vitamin D repleteness in breast cancer patients could enhance the efficacy of co-administered therapies in preventing spread to distant organs.

Curcumin as a great contributor for the treatment and mitigation of colorectal cancer

Cancer is one of the life-taking diseases worldwide and among cancer-related death; colorectal cancer is the third most. Though conventional methods of treatment are available, multidrug resistance and side effects are predominant. Physicians and scientists are working side by side to develop an effective medicament, which is safe and cost-effective. However, most failures are obtained when focused on the clinical perspective. This review mainly brings out the correlation between the curcumin and its use for the mitigation of colorectal cancer, the use of curcumin as a chemotherapeutic agent, chemosensitizer, and in a combination and synergistic approach. The pharmacokinetics and pharmacodynamics properties of curcumin and its formulation approach helps in giving an idea to develop new approaches for the treatment of colorectal cancer using curcumin.

Therapy Resistance in Cancers: Phenotypic, Metabolic, Epigenetic and Tumour Microenvironmental Perspectives

BACKGROUND

Chemoresistance is a vital problem in cancer therapy where cancer cells develop mechanisms to encounter the effect of chemotherapeutics, resulting in cancer recurrence. In addition, chemotherapy- resistant leads to the formation of a more aggressive form of cancer cells, which, in turn, contributes to the poor survival of patients with cancer.

OBJECTIVE

In this review, we aimed to provide an overview of how the therapy resistance property evolves in cancer cells, contributing factors and their role in cancer chemoresistance, and exemplified the problems of some available therapies.

METHODS

The published literature on various electronic databases including, Pubmed, Scopus, Google scholar containing keywords cancer therapy resistance, phenotypic, metabolic and epigenetic factors, were vigorously searched, retrieved and analyzed.

RESULTS

Cancer cells have developed a range of cellular processes, including uncontrolled activation of Epithelial- Mesenchymal Transition (EMT), metabolic reprogramming and epigenetic alterations. These cellular processes play significant roles in the generation of therapy resistance. Furthermore, the microenvironment where cancer cells evolve effectively contributes to the process of chemoresistance. In tumour microenvironment immune cells, Mesenchymal Stem Cells (MSCs), endothelial cells and cancer-associated fibroblasts (CAFs) contribute to the maintenance of therapy-resistant phenotype via the secretion of factors that promote resistance to chemotherapy.

CONCLUSION

To conclude, as these factors hinder successful cancer therapies, therapeutic resistance property of cancer cells is a subject of intense research, which in turn could open a new horizon to aim for developing efficient therapies.

Plasticity of Cancer Stem Cell: Origin and Role in Disease Progression and Therapy Resistance

In embryonic development and throughout life, there are some cells can exhibit phenotypic plasticity. Phenotypic plasticity is the ability of cells to differentiate into multiple lineages. In normal development, plasticity is highly regulated whereas cancer cells re-activate this dynamic ability for their own progression. The re-activation of these mechanisms enables cancer cells to acquire a cancer stem cell (CSC) phenotype- a subpopulation of cells with increased ability to survive in a hostile environment and resist therapeutic insults. There are several contributors fuel CSC plasticity in different stages of disease progression such as a complex network of tumour stroma, epidermal microenvironment and different sub-compartments within tumour. These factors play a key role in the transformation of tumour cells from a stable condition to a progressive state. In addition, flexibility in the metabolic state of CSCs helps in disease progression. Moreover, epigenetic changes such as chromatin, DNA methylation could stimulate the phenotypic change of CSCs. Development of resistance to therapy due to highly plastic behaviour of CSCs is a major cause of treatment failure in cancers. However, recent studies explored that plasticity can also expose the weaknesses in CSCs, thereby could be utilized for future therapeutic development. Therefore, in this review, we discuss how cancer cells acquire the plasticity, especially the role of the normal developmental process, tumour microenvironment, and epigenetic changes in the development of plasticity. We further highlight the therapeutic resistance property of CSCs attributed by plasticity. Also, outline some potential therapeutic options against plasticity of CSCs. Graphical Abstract .

TGF-β promote epithelial-mesenchymal transition via NF-κB/NOX4/ROS signal pathway in lung cancer cells

Epithelial-mesenchymal transition (EMT), transforming growth factor β(TGF-β) and reactive oxygen species(ROS) plays a central role in cancer metastasis. Moreover, nicotinamide adenine dinucleotide phosphate 4(NOX4) is one of the main sources of ROS in lung cancer cells suggesting that NOX4 is associated with tumor cell migration. NF-κB(Nuclear factor-Kappa-B) is known to regulate ROS-mediated EMT process by activating Snail transcription factor in A549 cells. The purpose of this study was to explore the relationship between NF-κB and NOX4 in ROS production during TGF-β induced EMT process. Several fractions have been pooled to evaluates the EMT process on lung cancer cells through real-time PCR, Western Blot and flow cytometry with DCFH-DA probe etc. Cells proliferation and migration activities were monitored by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay and wound healing assay respectively. The result showed that TGF-β induction decreased the expression of E-cadherin, increased the Vimentin and the EMT transcription factor Snail in A549 cells. DPI (Diphenyleneiodonium chloride, an inhibitor of NOX4) inhibited the NOX4 expression and reduced ROS production induced by TGF-β, but didn't affect the activation of NF-κB induced by TGF-β (P > 0.05). BAY11-7082 (an inhibitor of NF-κB) inhibited the NF-κB (p65) expression and prevented the increase of NOX4 expression and ROS production induced by TGF-β (P < 0.001), which has also verified reduced TGF-β induced cell migration by inhibiting the EMT process, and also reduced cell proliferation of A549 cells (P < 0.001). The current research confirmed the TGF-β mediated EMT process via NF-κB/NOX4/ROS signaling pathway, NF-κB and NOX4 are likely to be the potential therapeutic targets for lung cancer metastasis.

KRT6A Promotes EMT and Cancer Stem Cell Transformation in Lung Adenocarcinoma

Aim:

Keratin 6A is a type II cytokeratin which is important in forming nail bed, filiform papillae, the epithelial lining of oral mucosa, and esophagus; recently, keratin 6A was found hyperexpressed in different types of cancer. But, the biological function of keratin 6A in lung adenocarcinoma still remains unclear. Therefore, in current study, we investigated the biological role of keratin 6A in lung adenocarcinoma.

Methods:

By utilizing The Cancer Genome Atlas database, we investigated the expression profile of keratin 6A and its relationship with other clinical parameters in lung adenocarcinoma. The biological function of keratin 6A in lung adenocarcinoma was also investigated by using A549 and PC-9 lung cancer cell lines in vitro.

Results:

Our data indicate that, compared with normal lung tissue samples, keratin 6A was hyperexpressed in lung adenocarcinoma. Moreover, keratin 6A hyperexpression was positively correlated with lymph node positive and aggressive tumor T stage. Keratin 6A knockdown inhibited the cell proliferation, migration, and colony formation ability but not cell death in lung adenocarcinoma cells. In addition, we found keratin 6A exerted its phenotype via promoting cancer stem cells (CXCR4^high/CD133^high) transformation and epithelial–mesenchymal transition.

Conclusion:

In conclusion, current study suggests that hyperexpressed keratin 6A in lung adenocarcinoma promotes lung cancer proliferation and metastasis via epithelial–mesenchymal transition and cancer stem cells transformation.

EMT, cancer stem cells and autophagy; The three main axes of metastasis

Epithelial-mesenchymal transition (EMT) and Cancer stem-like cells (CSCs) are major factors contributing to the metastasis of cancer cells. Consequently, the signaling pathways involved in both processes are appropriate therapeutic targets in the treatment of metastasis. Autophagy is another process that has recently attracted the attention of many researchers; depending on the type of cancer and tissue and the stage of cancer, this process can play a dual role in the development of cancer cells. Studies on cancer cells have shown that different signaling pathways are involved in all three processes, namely, cancer stem cells, autophagy, and EMT. The purpose of this study was to investigate and elucidate the relationship between the effective signaling pathways in all three processes, which could play an effective role in determining appropriate therapeutic goals.

Aspirin Rescues Wnt-Driven Stem-like Phenotype in Human Intestinal Organoids and Increases the Wnt Antagonist Dickkopf-1

BACKGROUND & AIMS

Aspirin reduces colorectal cancer (CRC) incidence and mortality. Understanding the biology responsible for this protective effect is key to developing biomarker-led approaches for rational clinical use. Wnt signaling drives CRC development from initiation to progression through regulation of epithelial-mesenchymal transition (EMT) and cancer stem cell populations. Here, we investigated whether aspirin can rescue these proinvasive phenotypes associated with CRC progression in Wnt-driven human and mouse intestinal organoids.

METHODS

We evaluated aspirin-mediated effects on phenotype and stem cell markers in intestinal organoids derived from mouse (ApcMin/+ and Apcflox/flox) and human familial adenomatous polyposis patients. CRC cell lines (HCT116 and Colo205) were used to study effects on motility, invasion, Wnt signaling, and EMT.

RESULTS

Aspirin rescues the Wnt-driven cystic organoid phenotype by promoting budding in mouse and human Apc deficient organoids, which is paralleled by decreased stem cell marker expression. Aspirin-mediated Wnt inhibition in ApcMin/+ mice is associated with EMT inhibition and decreased cell migration, invasion, and motility in CRC cell lines. Chemical Wnt activation induces EMT and stem-like alterations in CRC cells, which are rescued by aspirin. Aspirin increases expression of the Wnt antagonist Dickkopf-1 in CRC cells and organoids derived from familial adenomatous polyposis patients, which contributes to EMT and cancer stem cell inhibition.

CONCLUSIONS

We provide evidence of phenotypic biomarkers of response to aspirin with an increased epithelial and reduced stem-like state mediated by an increase in Dickkopf-1. This highlights a novel mechanism of aspirin-mediated Wnt inhibition and potential phenotypic and molecular biomarkers for trials.

Central nervous system (CNS) tumor cell heterogeneity contributes to differential platinum-based response in an in vitro 2D and 3D cell culture approach

One of the models that best explains the cellular heterogeneity observed in central nervous system (CNS) tumors is the presence of cancer stem cells (CSCs). CSCs can originate from differentiated adult cells that return to an undifferentiated stage through the mechanism known as epithelial-mesenchymal transition (EMT). In this paper, we evaluated cellular and molecular heterogeneity and the participation of the epithelial-mesenchymal transition (EMT) in glioblastoma (U-87 MG and LN-18) and neuroblastoma (KELLY and IMR-32) cell lines cultured in monolayer (2D) and neurosphere (CSC enrichment- 3D) models. For this, after treatment with cisplatin, we studied different cell subpopulations by immunophenotyping using neural stem cell/progenitor markers (ALDH, CD24, CD56, and CD133), mesenchymal stem cell markers (CD73, CD90, CD105, and CD146) and hematopoietic markers (CD14, CD19, CD34, CD45, and HLA-DR) and mRNA expression profiles of genes related to EMT, such as ZEB1, TWIST1, TGFB1, STAT3, and lncRNA HOTAIR. In addition, we evaluated the growth capacity of residual cells when treated with cisplatin using the chorioallantoic membrane (CAM) model to study disease relapse. After treatment with cisplatin, we found that the expression of STAT3 and TGFB1 genes markedly increased in the neurosphere of the IMR-32 cell line, and TWIST1 was upregulated in the neurosphere of LN-18. Only the nontreated monolayer of LN-18, KELLY, and IMR-32 amplified the lncRNA HOTAIR. The IMR-32 cell line exhibited an enrichment of CD24⁺/ALDH⁺ and this cell subset decreased after cisplatin treatment. We observed the loss of CD146+/CD73+ cell subpopulations in U-87 MG monolayer and neurosphere models, after cisplatin treatment, while in LN-18 monolayer cisplatin-treated cells, CD73+/CD90+ cell subpopulations increased. Neuroblastoma cell lines showed CD14⁺/HLA-DR^- cell subpopulations representative of myeloid-derived suppressor cells (MDSCs). Tumors generated from residual cells, after exposure to cisplatin, grafted on CAM showed patterns of organization different from those of the controls. Thus, our findings strongly supported the idea that definitions of tumor phenotypic characteristics may help to establish better therapeutic strategies for the development of new drug targets.

Targeting MAD2 modulates stemness and tumorigenesis in human Gastric Cancer cell lines

Rationale: Gastric cancer (GC) is a solid tumor that contains subpopulations of cancer stem cells (CSCs), which are considered drivers of tumor initiation and metastasis; responsible for therapeutic resistance; and promoters of tumor relapse. The balance between symmetric and asymmetric division is crucial for stem cell maintenance. The objective of this study is to evaluate the role of MAD2, a key protein for proper mitotic checkpoint activity, in the tumorigenesis of GC.

Methods: Gastric cancer stem cells (GCSCs) were obtained from MKN45, SNU638 and ST2957 cell lines. Pluripotency and stemness markers were evaluated by RT-qPCR and autofluorescence and membrane markers by flow cytometry. Relevant signal transduction pathways were studied by WB. We analysed cell cycle progression, migration and invasion after modulation of MAD2 activity or protein expression levels in these in vitro models. In vivo assays were performed in a nude mouse subcutaneous xenograft model.

Results: We found that NANOG, CXCR4 and autofluorescence are common and consistent markers for the GCSCs analysed, with other markers showing more variability. The three main signalling pathways (Wnt/β-catenin; Hedgehog and Notch) were activated in GCSCs. Downregulation of MAD2 in MKN45^CSCs decreased the expression of markers CXCR4, CD133, CD90, LGR5 and VIM, without affecting cell cycle profile or therapy resistance. Moreover, migration, invasion and tumor growth were clearly reduced, and accordingly, we found that metalloprotease expression decreased. These results were accompanied by a reduction in the levels of transcription factors related with epithelial-to-mesenchymal transition.

Conclusions: We can conclude that MAD2 is important for GCSCs stemness and its downregulation in MKN45^CSCs plays a central role in GC tumorigenesis, likely through CXCR4-SNAI2-MMP1. Thus, its potential use in the clinical setting should be studied as its functions appear to extend beyond mitosis.

Tumor-Associated Macrophages in Osteosarcoma: From Mechanisms to Therapy

Osteosarcomas (OSs) are bone tumors most commonly found in pediatric and adolescent patients characterized by high risk of metastatic progression and recurrence after therapy. Effective therapeutic management of this disease still remains elusive as evidenced by poor patient survival rates. To achieve a more effective therapeutic management regimen, and hence patient survival, there is a need to identify more focused targeted therapies for OSs treatment in the clinical setting. The role of the OS tumor stroma microenvironment plays a significant part in the development and dissemination of this disease. Important components, and hence potential targets for treatment, are the tumor-infiltrating macrophages that are known to orchestrate many aspects of OS stromal signaling and disease progression. In particular, increased infiltration of M2-like tumor-associated macrophages (TAMs) has been associated with OS metastasis and poor patient prognosis despite currently used aggressive therapies regimens. This review aims to provide a summary update of current macrophage-centered knowledge and to discuss the possible roles that macrophages play in the process of OS metastasis development focusing on the potential influence of stromal cross-talk signaling between TAMs, cancer-stem cells and additional OSs tumoral microenvironment factors.

MicroRNAs Modulate Drug Resistance-Related Mechanisms in Hepatocellular Carcinoma

Primary liver cancer [hepatocellular carcinoma (HCC)] is one of the most common malignant tumors worldwide, causing serious health threats because of its high morbidity and mortality, rapid growth, and strong invasiveness. Patients with HCC frequently develop resistance to the current chemotherapeutic drugs, and this is largely attributed to the high-level heterogeneity of the tumor tissue. MicroRNAs (miRNAs) are a group of master regulators for multiple physiological and pathological processes and play important roles in the tumorigenesis. More recent studies have indicated that miRNAs also play a non-negligible role in the development of drug resistance in liver cancer. In this review, we summarize the data from the latest studies on the mechanisms of drug resistance in liver cancer, including autophagy, membrane transporters, epithelial-mesenchymal transitions (EMTs), tumor microenvironment, and genes and proteins that are associated with apoptosis. The data herein will provide valuable information for the development of novel approaches to tackle drug resistance in the management of liver cancer.

3D culture technologies of cancer stem cells: promising ex vivo tumor models

Cancer stem cells have been shown to be important in tumorigenesis processes, such as tumor growth, metastasis, and recurrence. As such, many three-dimensional models have been developed to establish an ex vivo microenvironment that cancer stem cells experience under in vivo conditions. Cancer stem cells propagating in three-dimensional culture systems show physiologically related signaling pathway profiles, gene expression, cell-matrix and cell-cell interactions, and drug resistance that reflect at least some of the tumor properties seen in vivo. Herein, we discussed the presently available Cancer stem cell three-dimensional culture models that use biomaterials and engineering tools and the biological implications of these models compared to the conventional ones.

Circular RNA cESRP1 sensitises small cell lung cancer cells to chemotherapy by sponging miR-93-5p to inhibit TGF-β signalling

Circular RNAs (circRNAs) are novel RNA molecules that play important roles in chemoresistance in different cancers, including breast and gastric cancers. However, whether circRNAs are involved in the response to chemotherapy in small cell lung cancer (SCLC) remains largely unknown. In this study, we observed that cESRP1 (circular RNA epithelial splicing regulatory protein-1) expression was significantly downregulated in the chemoresistant cells compared with the parental chemosensitive cells. cESRP1 enhanced drug sensitivity by repressing miR-93-5p in SCLC. Cytoplasmic cESRP1 could directly bind to miR-93-5p and inhibit the posttranscriptional repression mediated by miR-93-5p, thereby upregulating the expression of the miR-93-5p downstream targets Smad7/p21(CDKN1A) and forming a negative feedback loop to regulate transforming growth factor-β (TGF-β) mediated epithelial-mesenchymal transition. Furthermore, cESRP1 overexpression and TGF-β pathway inhibition both altered tumour responsiveness to chemotherapy in an acquired chemoresistant patient-derived xenograft model. Importantly, cESRP1 expression was downregulated in SCLC patient tissues and was associated with survival. Our findings reveal, for the first time, that cESRP1 plays crucial a role in SCLC chemosensitivity by sponging miR-93-5p to inhibit the TGF-β pathway, suggesting that cESRP1 may serve as a valuable prognostic biomarker and a potential therapeutic target in SCLC patients.

Current scenario of indole derivatives with potential anti-drug-resistant cancer activity

Cancer chemotherapy is frequently hampered by drug resistance, so the resistance to anticancer agents represents one of the major obstacles for the effective cancer treatment. Indole derivatives have the potential to act on diverse targets in cancer cells and exhibit promising activity against drug-resistant cancers. Moreover, some indole-containing compounds such as Semaxanib, Sunitinib, Vinorelbine, and Vinblastine have already been applied in clinics for various kinds of cancer even drug-resistant cancer therapy. Thus, indole derivatives are one of significant resources for the development of novel anti-drug-resistant cancer agents. This review focuses on the recent development of indole derivatives with potential therapeutic application for drug-resistant cancers, and the mechanisms of action, the critical aspects of design as well as structure-activity relationships, covering articles published from 2010 to 2020.

TYRO3 facilitates cell growth and metastasis via activation of the Wnt/β-catenin signaling pathway in human gastric cancer cells

It has become increasingly important to identify valuable therapeutic targets to improve the prognosis of cancer patients. Although emerging evidence has suggested TYRO3 as a potential therapeutic target in various types of cancers, less is known about its role in gastric cancer (GC) development. Herein, we investigated the functional and molecular mechanisms by which TYRO3 influenced GC. TYRO3 mRNA and protein were evaluated by quantitative real-time PCR (qRT-PCR), western blotting, and immunohistochemistry. Other methods including stable transfection of TYRO3 into GC cells, wound healing, Transwell assays, CCK-8 assays, colony formation assays, immunocytochemistry in vitro, and tumorigenesis in vivo were also conducted. Our results indicated that high levels of TYRO3 significantly correlated with clinical metastasis and poor prognoses in patients with GC. In addition, TYRO3 silencing distinctively suppressed GC cell growth, invasion, and metastasis both in vitro and in vivo. Conversely, TYRO3 overexpression led to the opposite effects. Mechanistic analyses revealed that the Wnt/β-catenin signaling pathway might be involved in TYRO3-facilitated GC cell behavior. Collectively, we demonstrated that elevated TYRO3 expression contributed to GC cell growth and metastasis via the Wnt/β-catenin pathway, suggesting a novel therapeutic target for GC.

Radiosensitization of Clioquinol Combined with Zinc in the Nasopharyngeal Cancer Stem-like Cells by Inhibiting Autophagy in Vitro and in Vivo

Loco-regional recurrence of nasopharyngeal carcinoma (NPC) after radiation therapy is one of the main types of treatment failure. This study is aimed to explore the possible causes of inside-field recurrence of NPC patients in order to develop effective treatment methods. Our study indicated that CD44 and autophagy proteins in tumor tissues of patients with recurrent NPC are higher than that of the relapse free patients. The in vitro experiments further confirmed that cancer stem cells (CSCs) were more radioresistant with enhanced autophagy activity. Treatment with clioquinol (CQ) combined with zinc could obviously enhance the radiosensitivity of CNE-2s cells through autophagy inhibition, activation of the caspase system and impairment of DNA damage repair. The in vivo experiments have further consolidated our findings. Our results suggest that CSCs and enhanced autophagy activity may be involved in the inside-field recurrence of NPC, and CQ combined with zinc could be an important therapeutic approach for recurrent NPC.

Epigenetic Silencing of Ubiquitin Specific Protease 4 by Snail1 Contributes to Macrophage-Dependent Inflammation and Therapeutic Resistance in Lung Cancer

There is a positive feedback loop driving tumorigenesis and tumor growth through coordinated regulation of epigenetics, inflammation, and stemness. Nevertheless, the molecular mechanism linking these processes is not well understood. In this study, we analyzed the correlation of de-ubiquitinases (DUBs) expression with survival data from the OncoLnc database. Among the DUBs analyzed, ubiquitin specific protease 4 (USP4) had the lowest negative Cox coefficient. Low expression of USP4 was associated with poor survival among lung cancer patients and was inversely correlated with expression of stemness and inflammation markers. Expression of USP4 were reduced at more advanced stages of lung cancer. Mechanistically, expression of USP4 was downregulated in snail1-overexpressing and stemness-enriched lung cancer cells. Snail1 was induced in lung cancer cells by interaction with macrophages, and epigenetically suppressed USP4 expression by promoter methylation. Stable knockdown of USP4 in lung cancer cells enhanced inflammatory responses, stemness properties, chemotherapy resistance, and the expression of molecules allowing escape from immunosurveillance. Further, mice injected with USP4 knockdown lung cancer cells demonstrated enhanced tumorigenesis and tumor growth. These results reveal that the Snail1-mediated suppression of USP4 is a potential mechanism to orchestrate epigenetic regulation, inflammation and stemness for macrophage-promoted tumor progression.

Calponin 3 promotes invasion and drug resistance of colon cancer cells

BACKGROUND

Calponin 3 (CNN3) is an actin-binding protein expressed in smooth muscle and non-smooth muscle cells. It is required for cytoskeletal rearrangement and wound healing.

AIM

To dissect the role of CNN3 in carcinogenesis with a focus on colon cancer.

METHODS

A total of 20 cancer cell lines (8 breast, 11 colon, and HeLa cervical cancer cell as a positive control for mesenchymal phenotype) and 57 formalin-fixed, paraffin-embedded sections from archived sporadic colorectal carcinomas were included in this study. CNN3 expression analysis by western blot or immunohistochemistry was followed by functional analyses. The CNN3 gene was silenced by specific small interfering RNA (commonly known as siRNA), followed by confirmation of the silencing efficiency by western blotting. Then, the silenced cells and control siRNA-transfected cells were analyzed for changes in epithelial and mesenchymal markers, invasion, and response to 5-fluoruracil treatment. We also performed proteomics analysis using a phospho-kinase array-based panel of 45 proteins.

RESULTS

CNN3 showed positive expression in 6/8 breast and 9/11 colon cancer lines and in HeLa cells. Interestingly, the colorectal adenocarcinoma line SW480 was negative, while the cell line developed from its matching lymph node metastasis (SW620) was positive for CNN3. CNN3 expression was fairly consistent with the metastatic phenotype in colon cancer because it was absent in one other colon cell line from a primary site and expressed in all others. We selected SW620 for subsequent functional analyses. CNN3-silenced SW620 cells showed a reduction in collagen invasion and loss of mesenchymal markers. CNN3 silencing caused an increase in the SW620 colon cancer cell sensitivity to 5-fluorouracil. Phospho-kinase array-based proteomics analysis showed that CNN3 silencing in SW620 reduced extracellular signal-regulated kinase, β-Catenin, mutant p53, c-Jun, and heat shock protein 60 activities but increased that of checkpoint kinase 2. CNN3 was expressed in 20/57 (35%) colon cancer cases as shown by immunohistochemistry. CNN3 was associated with a decrease in overall survival in colon cancer in silico.

CONCLUSION

These results show the involvement of CNN3 in lymph node metastasis and resistance to chemotherapy in colon cancer and suggest that significant oncogenic pathways are involved in these CNN3-related actions.

EFEMP2 Inhibits Breast Cancer Invasion And Metastasis In Vitro And In Vivo

Background

EGF-containing fibulin-like extracellular matrix protein 2 (EFEMP2) is an extracellular matrix (ECM) glycoprotein, which is regarded as potential prognostic biomarkers in some carcinoma. Little is known about the association of EFEMP2 and breast cancer.

Methods

EFEMP2 expressions in normal breast tissue, benign fibroadenoma, breast cancer, the normal mammary epithelial cell line, and 4 different invasive breast cancer cell lines were evaluated by immunohistochemistry (IHC) or immunocytochemistry (ICC) and real time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR). Expression and prognostic value of EFEMP2 in breast cancer were verified by the Public databases (Oncomine and Kaplan-Meier plotter database). Lentiviral vector with EFEMP2 cDNA was constructed and used to infect breast cancer cell lines to investigate the effects of EFEMP2 on the biological behavior of breast cancer cells by functional in vitro and in vivo assays.

Results

Down-regulated EFEMP2 expression was found in breast cancer tissues and cells, and low expression of EFEMP2 was associated with poor prognosis in patients with breast cancer. Analysis by the Public database leaded to the same conclusion. Up-regulated EFEMP2 expression significantly hampered the invasion and metastasis abilities of breast cancer cells and the process of epithelial interstitial transformation (EMT) via the Wnt/β-catenin pathway.

Conclusion

EFEMP2 expression was lower in breast cancer and closely related to the prognosis of patients, its anti-oncogenic roles indicated the underlying therapeutic target for the future treatment of breast cancer.

Therapeutic Strategies Targeting Cancer Stem Cells and Their Microenvironment

Cancer stem cells (CSCs) have been demonstrated in a variety of tumors and are thought to act as a clonogenic core for the genesis of new tumor growth. This small subpopulation of cancer cells has been proposed to help drive tumorigenesis, metastasis, recurrence and conventional therapy resistance. CSCs show self-renewal and flexible clonogenic properties and help define specific tumor microenvironments (TME). The interaction between CSCs and TME is thought to function as a dynamic support system that fosters the generation and maintenance of CSCs. Investigation of the interaction between CSCs and the TME is shedding light on the biologic mechanisms underlying the process of tumor malignancy, metastasis, and therapy resistance. We summarize recent advances in CSC biology and their environment, and discuss the challenges and future strategies for targeting this biology as a new therapeutic approach.

Epithelial-mesenchymal plasticity-engaging stemness in an interplay of phenotypes

Cancer is a genetic disease which results in a functional imbalance between tumour-repressive and oncogenic signals. The WHO highlights the burden of this indomitable disease, listing it as the second leading cause of death globally. The major cause of cancer-related death is rarely the effect of the primary tumour itself, but rather, the devastating spread of cancer cells in metastases. Epithelial-mesenchymal plasticity (EMP)-termed as the ability of cells to maintain its plasticity and transit between epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) states-plays a fundamental role in cancer metastasis. These cell transitions allow them migrate from the primary tumour and invade the secondary site. EMP is associated with migration, invasion, colonisation, self-renewal and drug resistance. This review briefly elucidates the mechanism of EMP and the association between cancer stem cells (CSCs) and circulating tumour cells (CTCs), biomarkers and signalling pathways involved in EMP as well as drug resistance and therapeutic targeting.

New Insights about the Wnt/β-Catenin Signaling Pathway in Primary Bone Tumors and Their Microenvironment: A Promising Target to Develop Therapeutic Strategies?

Osteosarcoma and Ewing sarcoma are the most common malignant primary bone tumors mainly occurring in children, adolescents and young adults. Current standard therapy includes multidrug chemotherapy and/or radiation specifically for Ewing sarcoma, associated with tumor resection. However, patient survival has not evolved for the past decade and remains closely related to the response of tumor cells to chemotherapy, reaching around 75% at 5 years for patients with localized forms of osteosarcoma or Ewing sarcoma but less than 30% in metastatic diseases and patients resistant to initial chemotherapy. Despite Ewing sarcoma being characterized by specific EWSR1-ETS gene fusions resulting in oncogenic transcription factors, currently, no targeted therapy could be implemented. It seems even more difficult to develop a targeted therapeutic strategy in osteosarcoma which is characterized by high complexity and heterogeneity in genomic alterations. Nevertheless, the common point between these different bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Therefore, targeting different actors of the bone tumor microenvironment has been hypothesized to develop new therapeutic strategies. In this context, it is well known that the Wnt/β-catenin signaling pathway plays a key role in cancer development, including osteosarcoma and Ewing sarcoma as well as in bone remodeling. Moreover, recent studies highlight the implication of the Wnt/β-catenin pathway in angiogenesis and immuno-surveillance, two key mechanisms involved in metastatic dissemination. This review focuses on the role played by this signaling pathway in the development of primary bone tumors and the modulation of their specific microenvironment.

Cellular and molecular biology of cancer stem cells in melanoma: Possible therapeutic implications

Malignant melanoma is a tumor characterized by a very high level of heterogeneity, responsible for its malignant behavior and ability to escape from standard therapies. In this review we highlight the molecular and biological features of the subpopulation of cancer stem cells (CSCs), well known to be characterized by self-renewal properties, deeply involved in triggering the processes of tumor generation, metastasis, progression and drug resistance. From the molecular point of view, melanoma CSCs are identified and characterized by the expression of stemness markers, such as surface markers, ATP-binding cassette (ABC) transporters, embryonic stem cells and intracellular markers. These cells are endowed with different functional features. In particular, they play pivotal roles in the processes of tumor dissemination, epithelial-to-mesenchymal transition (EMT) and angiogenesis, mediated by specific intracellular signaling pathways; moreover, they are characterized by a unique metabolic reprogramming. As reported for other types of tumors, the CSCs subpopulation in melanoma is also characterized by a low immunogenic profile as well as by the ability to escape the immune system, through the expression of a negative modulation of T cell functions and the secretion of immunosuppressive factors. These biological features allow melanoma CSCs to escape standard treatments, thus being deeply involved in tumor relapse. Targeting the CSCs subpopulation is now considered an attractive treatment strategy; in particular, combination treatments, based on both CSCs-targeting and standard drugs, will likely increase the therapeutic options for melanoma patients. The characterization of CSCs in liquid biopsies from single patients will pave the way towards precision medicine.

MicroRNA‑214 suppresses the viability, migration and invasion of human colorectal carcinoma cells via targeting transglutaminase 2

Colorectal carcinoma (CRC) is a common malignancy of the digestive tract. MicroRNA (miR)-214 is considered a key hub that controls tumor networks; therefore, the effects of miR-214 on CRC were examined and its target gene was investigated in this study. The expression levels of transglutaminase 2 (TGM2) and miR-214 were detected in CRC and adjacent normal tissues by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, and luciferase activity was analyzed by dual luciferase reporter analysis. In addition, cell viability, invasion and migration were measured by Cell Counting kit-8 and Transwell assays, respectively. The expression levels of epithelial-mesenchymal transition-related proteins, and phosphoinositide-3 kinase (PI3K)/protein kinase B (Akt) signaling-associated factors were detected using RT-qPCR and western blotting. The results demonstrated that miR-214 expression was downregulated in CRC tissue, whereas TGM2 expression was upregulated. According to TargetScan prediction, miR-214 possesses a binding site to TGM2. In addition, transfection with miR-214 mimics markedly suppressed the viability of LoVo cells. miR-214 overexpression also inhibited cell invasion and migration by increasing E-cadherin and tissue inhibitor of metalloproteinases-2 expression, and decreasing matrix metalloproteinase (MMP)-2 and MMP-9 expression. Furthermore, miR-214 downregulated phosphorylation of PI3K and Akt; however, the expression levels of total PI3K and Akt were not affected by miR-214. In conclusion, this study indicated that TGM2 was a target gene of miR-214, and a negative correlation between miR-214 and TGM2 expression was determined in CRC. Notably, miR-214 markedly suppressed the viability, invasion and migration of CRC cells, which may be associated with a downregulation in PI3K/Akt signaling. These findings suggested that miR-214 may be considered a novel target for the treatment of CRC.

miR-27b-3p/MARCH7 regulates invasion and metastasis of endometrial cancer cells through Snail-mediated pathway

Ubiquitin E3 ligase membrane-associated RING-CH-type finger 7 (MARCH7), also known as axotrophin, was originally identified in mouse embryonic stem cells. MARCH7 is involved in T-cell proliferation, neuronal development, and the immune system. However, its role in endometrial cancer (EC) remains unclear. This study aimed to investigate the role of MARCH7 in EC. Quantitative polymerase chain reaction, immunohistochemistry, and western blot analysis were used to examine the expression of MARCH7, E-cadherin, Snail, and Vimentin in EC cell lines or clinical specimens. The role of MARCH7 in maintaining EC cell malignant phenotype was determined by transwell assay and using xenograft tumor model. Dual-luciferase reporter gene assay was performed to determine whether MARCH7 is an authentic target of miR-27b-3p. Our data showed that the expression level of MARCH7 in EC tissues was higher than that in normal endometrium tissues. The level of MARCH7 was positively associated with that of Snail and Vimentin, clinical stage, and histological grade, while negatively associated with that of E-cadherin. Knockdown of MARCH7 inhibited the invasion and metastasis of EC cells in vitro and in vivo. The opposite effect was observed after overexpressing MARCH7. MARCH7 promoted invasion and metastasis of EC cells via the Snail-mediated pathway. Furthermore, MARCH7 was demonstrated to be an authentic target of miR-27b-3p, and miR-27b-3p decreased the stimulus effect induced by MARCH7. These data indicate that MARCH7 may be an oncogenic factor and a therapeutic target for EC. miR-27b-3p/MARCH7 may also regulate EC cell invasion and metastasis via the Snail-mediated pathway.

A Microwell-Assisted Multiaptamer Immunomagnetic Platform for Capture and Genetic Analysis of Circulating Tumor Cells

Detection of circulating tumor cells (CTCs) in peripheral blood is of paramount significance for cancer diagnosis, progress evaluation, and individualized therapy. However, the rareness and heterogeneity of CTCs introduces significant challenges in the capture of cancer cells as well as downstream genetic analysis. In this work, a microwell-assisted multiaptamer immunomagnetic platform (MMAIP) is proposed for highly efficient capture of CTCs with minimum influence of heterogeneity. Assisted by a microwell chip, the purity of CTCs is greatly improved, thus meeting the requirement of downstream gene analysis. This is, as far as is known, the first aptamer based platform enabling mutation analysis of the captured CTCs from cancer patients, which will contribute to the practical application of aptamers in clinics.