CD44 is functionally crucial for driving lung cancer stem cells metastasis through Wnt/β-catenin-FoxM1-Twist signaling

Huaier enhances the tumor-killing effect and reverses gemcitabine-induced stemness by suppressing FoxM1

BACKGROUND

Gemcitabine is the first-line chemotherapy drug that can easily cause chemotherapy resistance. Huaier is a traditional Chinese medicine and shows an antitumor effect in pancreatic cancer, but whether it can enhance the gemcitabine chemotherapeutic response and the potential mechanism remain unknown.

PURPOSE

This study was performed to explore the effect of Huaier in promoting the tumor-killing effect of gemcitabine and elucidate the possible mechanism in pancreatic cancer.

METHODS

Cell Counting Kit-8 assays and colony formation assays were used to detect proliferation after different treatments. Protein coimmunoprecipitation was applied to demonstrate protein interactions. Nuclear protein extraction and immunofluorescence were used to confirm the intracellular localization of the proteins. Western blotting was performed to detect cell proliferation-related protein expression or cancer stem cell-associated protein expression. Sphere formation assays and flow cytometry were used to assess the stemness of pancreatic cancer cells. The in vivo xenograft model was used to confirm the inhibitory effect under physiological conditions, and immunohistochemistry was used to detect protein expression.

RESULTS

Huaier suppressed the proliferation and stem cell-like properties of pancreatic cancer cells. We found that Huaier suppressed the expression of forkhead box protein M1 (FoxM1). In addition, Huaier inhibited FoxM1 function by blocking its nuclear translocation. Treatment with Huaier reversed the stemness induced by gemcitabine in a FoxM1-dependent manner. Furthermore, we verified the above results by an in vivo study, which reached the same conclusion as those in vitro.

CONCLUSION

Overall, this study illustrates that Huaier augments the tumor-killing effect of gemcitabine through suppressing the stemness induced by gemcitabine in a FoxM1-dependent way. These results indicate that Huaier can be applied to overcome gemcitabine resistance.

CD44 and its implication in neoplastic diseases

CD44, a nonkinase single span transmembrane glycoprotein, is a major cell surface receptor for many other extracellular matrix components as well as classic markers of cancer stem cells and immune cells. Through alternative splicing of CD44 gene, CD44 is divided into two isoforms, the standard isoform of CD44 (CD44s) and the variant isoform of CD44 (CD44v). Different isoforms of CD44 participate in regulating various signaling pathways, modulating cancer proliferation, invasion, metastasis, and drug resistance, with its aberrant expression and dysregulation contributing to tumor initiation and progression. However, CD44s and CD44v play overlapping or contradictory roles in tumor initiation and progression, which is not fully understood. Herein, we discuss the present understanding of the functional and structural roles of CD44 in the pathogenic mechanism of multiple cancers. The regulation functions of CD44 in cancers-associated signaling pathways is summarized. Moreover, we provide an overview of the anticancer therapeutic strategies that targeting CD44 and preclinical and clinical trials evaluating the pharmacokinetics, efficacy, and drug-related toxicity about CD44-targeted therapies. This review provides up-to-date information about the roles of CD44 in neoplastic diseases, which may open new perspectives in the field of cancer treatment through targeting CD44.

Mechanisms of angiogenesis in tumour

Angiogenesis is essential for tumour growth and metastasis. Antiangiogenic factor-targeting drugs have been approved as first line agents in a variety of oncology treatments. Clinical drugs frequently target the VEGF signalling pathway during sprouting angiogenesis. Accumulating evidence suggests that tumours can evade antiangiogenic therapy through other angiogenesis mechanisms in addition to the vascular sprouting mechanism involving endothelial cells. These mechanisms include (1) sprouting angiogenesis, (2) vasculogenic mimicry, (3) vessel intussusception, (4) vascular co-option, (5) cancer stem cell-derived angiogenesis, and (6) bone marrow-derived angiogenesis. Other non-sprouting angiogenic mechanisms are not entirely dependent on the VEGF signalling pathway. In clinical practice, the conversion of vascular mechanisms is closely related to the enhancement of tumour drug resistance, which often leads to clinical treatment failure. This article summarizes recent studies on six processes of tumour angiogenesis and provides suggestions for developing more effective techniques to improve the efficacy of antiangiogenic treatment.

Cancer stem cells: Recent trends in cancer therapy

Cancer stem cells (CSCs) are a subset of tumor cells that were first identified in blood cancers (leukemia) and are considered promising therapeutic targets in cancer treatment. These cells are the cause of many malignancies including metastasis, heterogeneity, drug resistance, and tumor recurrence. They carry out these activities through multiple transcriptional programs and signaling pathways. This review summarizes the characteristics of cancer stem cells, explains their key signaling pathways and factors, and discusses targeted therapies for cancer stem cells. Investigating these mechanisms and signaling pathways responsible for treatment failure may help identify new therapeutic pathways in cancer.

The Nexus of Inflammation-Induced Epithelial-Mesenchymal Transition and Lung Cancer Progression: A Roadmap to Pentacyclic Triterpenoid-Based Therapies

Lung cancer is the leading cause of cancer-related death worldwide. Its high mortality is partly due to chronic inflammation that accompanies the disease and stimulates cancer progression. In this review, we analyzed recent studies and highlighted the role of the epithelial-mesenchymal transition (EMT) as a link between inflammation and lung cancer. In the inflammatory tumor microenvironment (iTME), fibroblasts, macrophages, granulocytes, and lymphocytes produce inflammatory mediators, some of which can induce EMT. This leads to increased invasiveness of tumor cells and self-renewal of cancer stem cells (CSCs), which are associated with metastasis and tumor recurrence, respectively. Based on published data, we propose that inflammation-induced EMT may be a potential therapeutic target for the treatment of lung cancer. This prospect is partially realized in the development of EMT inhibitors based on pentacyclic triterpenoids (PTs), described in the second part of our study. PTs reduce the metastatic potential and stemness of tumor cells, making PTs promising candidates for lung cancer therapy. We emphasize that the high diversity of molecular mechanisms underlying inflammation-induced EMT far exceeds those that have been implicated in drug development. Therefore, analysis of information on the relationship between the iTME and EMT is of great interest and may provide ideas for novel treatment approaches for lung cancer.

FBXO7 Confers Mesenchymal Properties and Chemoresistance in Glioblastoma by Controlling Rbfox2-Mediated Alternative Splicing

Mesenchymal glioblastoma (GBM) is highly resistant to radio-and chemotherapy and correlates with worse survival outcomes in GBM patients; however, the underlying mechanism determining the mesenchymal phenotype remains largely unclear. Herein, it is revealed that FBXO7, a substrate-recognition component of the SCF complex implicated in the pathogenesis of Parkinson's disease, confers mesenchymal properties and chemoresistance in GBM by controlling Rbfox2-mediated alternative splicing. Specifically, FBXO7 ubiquitinates Rbfox2 Lys249 through K63-linked ubiquitin chains upon arginine dimethylation at Arg341 and Arg441 by PRMT5, leading to Rbfox2 stabilization. FBXO7 controls Rbfox2-mediated splicing of mesenchymal genes, including FoxM1, Mta1, and Postn. FBXO7-induced exon Va inclusion of FoxM1 promotes FoxM1 phosphorylation by MEK1 and nuclear translocation, thereby upregulates CD44, CD9, and ID1 levels, resulting in GBM stem cell self-renewal and mesenchymal transformation. Moreover, FBXO7 is stabilized by temozolomide, and FBXO7 depletion sensitizes tumor xenografts in mice to chemotherapy. The findings demonstrate that the FBXO7-Rbfox2 axis-mediated splicing contributes to mesenchymal transformation and tumorigenesis, and targeting FBXO7 represents a potential strategy for GBM treatment.

Identification of cancer stemness and M2 macrophage-associated biomarkers in lung adenocarcinoma

Objective

Cancer stemness and M2 macrophages are intimately linked to the prognosis of lung adenocarcinoma (LUAD). For this reason, this investigation sought to identify the key genes relevant to cancer stemness and M2 macrophages, explore the relationship between these genes and clinical characteristics, and determine the potential mechanism.

Methods

LUAD transcriptomic data was analyzed from The Cancer Genome Atlas (TCGA) as well as the Gene Expression Omnibus databases. Differential expression analysis was performed to discern abnormally expressed genes between LUAD and control samples in TCGA cohort. The Cell type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) algorithm was applied to determine varyingly infiltrated immune cells in LUAD compared with the control samples in TCGA cohort. Weighted correlation network analysis (WGCNA) was performed to identify genes associated with mRNA expression-based stemness index (mRNAsi) and M2 macrophages. Least absolute shrinkage and selection operator (LASSO), RandomForest (RF) and support vector machine-recursive feature elimination (SVM-RFE) machine learning methods were conducted to detect gene signatures. Global survival evaluation (Kaplan-Meier curve) was applied to investigate the relationship between gene signatures and the survival time of LUAD patients. Receiver operating characteristic (ROC) curves were produced to define biomarkers relevant to diagnosis. Gene Set Enrichment Analysis (GSEA) was performed to probe the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to diagnostic biomarkers. The public single-cell dataset of LUAD (GSE123902) was used to investigate the expression differences of diagnostic biomarkers in various cell types in LUAD. Real-time quantitative PCR (qRT-PCR) was performed to confirm key genes in lung adenocarcinoma cells.

Results

A total of 5,410 differentialy expressed genes (DEGs) as well as 15 differentially infiltrated immune cells were identified between LUAD and control sepcimens in TCGA cohort. Thirty-seven DEGs were associated with both M2 macrophages and mRNAsi according to the WGCNA analysis. Sixteen common gene signatures were obtained using three diverse algorithms. CBFA2T3, DENND3 and FCAMR were correlated to overall and disease-free survival of LUAD patients. ROC curves revealed that CBFA2T3 and DENND3 expression accurately classified LUAD and control samples. The results of single cell related analysis showed that two diagnostic biomarkers expressions were differed between the different tissue sources in M2-like macrophages. QRT-PCR demonstrated the mRNA expressions of CBFA2T3 and DENND3 were upregulated in lung adenocarcinoma cells A549 and H2122.

Conclusion

Our study identified CBFA2T3 and DENND3 as key genes associated with mRNAsi and M2 macrophages in LUAD and investigated the potential molecular mechanisms underlying this relationship.

The role of tumor microenvironment on cancer stem cell fate in solid tumors

In the last few decades, the role of cancer stem cells in initiating tumors, metastasis, invasion, and resistance to therapies has been recognized as a potential target for tumor therapy. Understanding the mechanisms by which CSCs contribute to cancer progression can help to provide novel therapeutic approaches against solid tumors. In this line, the effects of mechanical forces on CSCs such as epithelial-mesenchymal transition, cellular plasticity, etc., the metabolism pathways of CSCs, players of the tumor microenvironment, and their influence on the regulating of CSCs can lead to cancer progression. This review focused on some of these mechanisms of CSCs, paving the way for a better understanding of their regulatory mechanisms and developing platforms for targeted therapies. While progress has been made in research, more studies will be required in the future to explore more aspects of how CSCs contribute to cancer progression. Video Abstract.

Cell adhesion molecules and immunotherapy in advanced non-small cell lung cancer: Current process and potential application

Advanced non-small cell lung cancer (NSCLC) is a severe disease and still has high mortality rate after conventional treatment (e.g., surgical resection, chemotherapy, radiotherapy and targeted therapy). In NSCLC patients, cancer cells can induce immunosuppression, growth and metastasis by modulating cell adhesion molecules of both cancer cells and immune cells. Therefore, immunotherapy is increasingly concerned due to its promising anti-tumor effect and broader indication, which targets cell adhesion molecules to reverse the process. Among these therapies, immune checkpoint inhibitors (mainly anti-PD-(L)1 and anti-CTLA-4) are most successful and have been adapted as first or second line therapy in advanced NSCLC. However, drug resistance and immune-related adverse reactions restrict its further application. Further understanding of mechanism, adequate biomarkers and novel therapies are necessary to improve therapeutic effect and alleviate adverse effect.

Dysregulated FOXM1 signaling in the regulation of cancer stem cells

Since the introduction of the cancer stem cell (CSC) paradigm, significant advances have been made in understanding the functional and biological plasticity of these elusive components in malignancies. Endowed with self-renewing abilities and multilineage differentiation potential, CSCs have emerged as cellular drivers of virtually all facets of tumor biology, including metastasis, tumor recurrence/relapse, and drug resistance. The functional and biological characteristics of CSCs, such as self-renewal, cell fate decisions, survival, proliferation, and differentiation are regulated by an array of extracellular factors, signaling pathways, and pluripotent transcriptional factors. Besides the well-characterized regulatory role of transcription factors OCT4, SOX2, NANOG, KLF4, and MYC in CSCs, evidence for the central role of Forkhead box transcription factor FOXM1 in the establishment, maintenance, and functions of CSCs is accumulating. Conventionally identified as a master regulator of the cell cycle, a comprehensive understanding of this molecule has revealed its multifarious oncogenic potential and uncovered its role in angiogenesis, invasion, migration, self-renewal, and drug resistance. This review compiles the large body of literature that has accumulated in recent years that provides evidence for the mechanisms by which FOXM1 expression promotes stemness in glioblastoma, breast, colon, ovarian, lung, hepatic, and pancreatic carcinomas. We have also compiled the data showing the association of stem cell mediators with FOXM1 using TCGA mRNA expression data. Further, the prognostic importance of FOXM1 and other stem cell markers is presented. The delineation of FOXM1-mediated regulation of CSCs can aid in the development of molecularly targeted pharmacological approaches directed at the selective eradication of CSCs in several human malignancies.

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

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

Targeting Cancer Stem Cells: Therapeutic and diagnostic strategies by the virtue of nanoparticles

Cancer stem cells (CSCs) are the subpopulation of cells present within a tumor with the properties of self-renewing, differentiating, and proliferating. Owing to the presence of ATP-binding cassette drug pumps and increased expression of anti-apoptotic proteins, the conventional chemotherapeutic agents have failed to eliminate CSCs resulting in relapse and resistance of cancer. Therefore, to obtain long-lasting clinical responses and avoid the recurrence of cancer, it is crucial to develop an efficient strategy targeting CSCs by either employing a differentiation therapy or specifically delivering drugs to CSCs. Several intracellular and extracellular cancer specific biomarkers are overexpressed by CSCs and are utilized as targets for the development of new approaches in the diagnosis and treatment of CSCs. Moreover, several nanostructured particles, alone or in combination with current treatment approaches, have been used to improve the detection, imaging, and targeting of CSCs, thus addressing the limitations of cancer therapies. Targeting CSC surface markers, stemness-related signaling pathways, and tumor microenvironmental signals has improved the detection and eradication of CSCs and, therefore, tumor diagnosis and treatment. This review summarizes a variety of promising nanoparticles targeting the surface biomarkers of CSCs for the detection and eradication of tumor-initiating stem cells, used in combination with other treatment regimens.

Hyaluronan network: a driving force in cancer progression

Hyaluronan is one of the most abundant macromolecules of the extracellular matrix and regulates several physiological cell and tissue properties. However, hyaluronan has been shown to accumulate together with its receptors in various cancers. In tumors, accumulation of hyaluronan system components (hyaluronan synthesizing/degrading enzymes and interacting proteins) associates with poor outcomes of the patients. In this article, we review the main roles of hyaluronan in normal physiology and cancer, and further discuss the targeting of hyaluronan system as an applicable therapeutic strategy.

BTB and CNC homology 1 (Bach1) induces lung cancer stem cell phenotypes by stimulating CD44 expression

BACKGROUND

Growing evidence suggests that cancer stem cells (CSCs) are responsible for cancer initiation in tumors. Bach1 has been identified to contribute to several tumor progression, including lung cancer. The role of Bach1 in CSCs remains poorly known. Therefore, the function of Bach1 on lung CSCs was focused currently.

METHODS

The expression of Bach1, CD133, CD44, Sox2, Nanog and Oct4 mRNA was assessed using Real-Time Quantitative Reverse Transcription PCR (RT-qPCR). Protein expression of Bach1, CD133, CD44, Sox2, Nanog, Oct4, p53, BCL2, BAX, p-p38, p-AKT1, c-Fos and c-Jun protein was analyzed by western blotting. 5-ethynyl-29-deoxyuridine (EdU), colony formation, Flow cytometry analysis and transwell invasion assay were carried out to analyze lung cancer cell proliferation, apoptosis and invasion respectively. Tumor sphere formation assay was utilized to evaluate spheroid capacity. Flow cytometry analysis was carried out to isolate CD133 or CD44 positive lung cancer cells. The relationship between Bach1 and CD44 was verified using ChIP-qPCR and dual-luciferase reporter assay. Xenograft tumor tissues were collected for hematoxylin and eosin (HE) staining and IHC analysis to evaluate histology and Ki-67.

RESULTS

The ratio of CD44 + CSCs from A549 and SPC-A1 cells were significantly enriched. Tumor growth of CD44 + CSCs was obviously suppressed in vivo compared to CD44- CSCs. Bach1 expression was obviously increased in CD44 + CSCs. Then, via using the in vitro experiment, it was observed that CSCs proliferation and invasion were greatly reduced by the down-regulation of Bach1 while cell apoptosis was triggered by knockdown of Bach1. Loss of Bach1 was able to repress tumor-sphere formation and tumor-initiating CSC markers. A repression of CSCs growth and metastasis of shRNA-Bach1 was confirmed using xenograft models and caudal vein injection. The direct interaction between Bach1 and CD44 was confirmed by ChIP-qPCR and dual-luciferase reporter assay. Furthermore, mitogen-activated protein kinases (MAPK) signaling pathway was selected and we proved the effects of Bach1 on lung CSCs were associated with the activation of the MAPK pathway. As manifested, loss of Bach1 was able to repress p-p38, p-AKT1, c-Fos, c-Jun protein levels in lung CSCs. Inhibition of MAPK signaling remarkably restrained lung CSCs growth and CSCs properties induced by Bach1 overexpression.

CONCLUSION

In summary, we imply that Bach1 demonstrates great potential for the treatment of lung cancer metastasis and recurrence via activating CD44 and MPAK signaling.

Modulation of Immune Components on Stem Cell and Dormancy in Cancer

Cancer stem cells (CSCs) refer to a certain subpopulation within the tumor entity that is characterized by restricted cellular proliferation and multipotent differentiation potency. The existence of CSCs has been proven to contribute to the heterogeneity of malignancies, accounting for intensified tumorigenesis, treatment resistance, and metastatic spread. Dormancy was proposed as a reversible state of cancer cells that are temporarily arrested in the cell cycle, possessing several hallmarks that facilitate their survival within a devastating niche. This transient period is evoked to enter an actively proliferating state by multiple regulatory alterations, and one of the most significant and complex factors comes from local and systemic inflammatory reactions and immune components. Although CSCs and dormant cancer cells share several similarities, the clear relationship between these two concepts remains unclear. Thus, the detailed mechanism of immune cells interacting with CSCs and dormant cancer cells also warrants elucidation for prevention of cancer relapse and metastasis. In this review, we summarize recent findings and prospective studies on CSCs and cancer dormancy to conclude the relationship between these two concepts. Furthermore, we aim to outline the mechanism of immune components in interfering with CSCs and dormant cancer cells to provide a theoretical basis for the prevention of relapse and metastasis.

Cancer Stem Cell for Tumor Therapy

Simple Summary

Although many methods have been applied in clinical treatment for tumors, they still always show a poor prognosis. Molecule targeted therapy has revolutionized tumor therapy, and a proper target must be found urgently. With a crucial role in tumor development, metastasis and recurrence, cancer stem cells have been found to be a feasible and potential target for tumor therapy. We list the unique biological characteristics of cancer stem cells and summarize the recent strategies to target cancer stem cells for tumor therapy, through which we hope to provide a comprehensive understanding of cancer stem cells and find a better combinational strategy to target cancer stem cells for tumor therapy.

Abstract

Tumors pose a significant threat to human health. Although many methods, such as operations, chemotherapy and radiotherapy, have been proposed to eliminate tumor cells, the results are unsatisfactory. Targeting therapy has shown potential due to its specificity and efficiency. Meanwhile, it has been revealed that cancer stem cells (CSCs) play a crucial role in the genesis, development, metastasis and recurrence of tumors. Thus, it is feasible to inhibit tumors and improve prognosis via targeting CSCs. In this review, we provide a comprehensive understanding of the biological characteristics of CSCs, including mitotic pattern, metabolic phenotype, therapeutic resistance and related mechanisms. Finally, we summarize CSCs targeted strategies, including targeting CSCs surface markers, targeting CSCs related signal pathways, targeting CSC niches, targeting CSC metabolic pathways, inducing differentiation therapy and immunotherapy (tumor vaccine, CAR-T, oncolytic virus, targeting CSCs–immune cell crosstalk and immunity checkpoint inhibitor). We highlight the potential of immunity therapy and its combinational anti-CSC therapies, which are composed of different drugs working in different mechanisms.

Inhibition of FSTL3 abates the proliferation and metastasis of renal cell carcinoma via the GSK-3β/β-catenin signaling pathway

Renal cell carcinoma (RCC) is a lethal malignancy of the genitourinary system. Follistatin-like 3 (FSTL3), which mediates cell differentiation and growth, acts as a biomarker of tumors and participates in cancer development and progression. Presently, the FSTL3’s functions in RCC were investigated. Quantitative reverse transcription PCR (qRT-PCR), Western Blot, and enzyme linked immunosorbent assay (ELISA) were conducted to verify FSTL3 expression in RCC tissues and cell lines. BrdU assay and CCK8 experiment were made to monitor cell proliferation. Transwell was implemented to examine the invasion of the cells. Flow cytometry analyzed cell apoptosis, and Western Blot evaluated the protein levels of E-cadherin, Twist, and Slug. In the meantime, the protein profiles of the GSK-3β, β-catenin, and TGF-β signaling pathways were ascertained. Moreover, the Xenograft tumor model was constructed in nude mice for measuring tumor growth in vivo. The statistics showed that FSTL3 presented an overexpression in RCC, and patients with a lower expression of FSTL3 manifested a better prognosis. Down-regulated FSTL3 hampered the proliferation, invasion, EMT, and tumor growth of RCC cells and caused cell apoptosis. On the contrary, FSTL3 overexpression enhanced the malignant behaviors of RCC cells. Furthermore, FSTL3 knockdown bolstered GSK-3β, suppressed β-catenin, and reduced BMP1-SMAD pathway activation. Inhibited β-catenin substantially mitigated FSTL3-mediated promoting functions in RCC. In short, FSTL3 functions as an oncogene in RCC by modulating the GSK-3β/β-catenin signaling pathway.

CD44 Promotes Lung Cancer Cell Metastasis through ERK-ZEB1 Signaling

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

Self-targeted polymersomal co-formulation of doxorubicin, camptothecin and FOXM1 aptamer for efficient treatment of non-small cell lung cancer

In spite of huge developments in cancer treatment, versatile combinational formulations of different chemotherapeutic agents to enhance anticancer activity while reducing systemic toxicity still remains a challenge. In this regard, in the current study, an amphiphilic hyaluronic acid-b-polycaprolactone diblock copolymer was synthesized using "click chemistry". The synthesized copolymer was self-assembled to form polymersomal structures for co-encapsulation of hydrophilic doxorubicin (DOX) and hydrophobic camptothecin (CPT) in their interior aqueous compartment and their bilayer, respectively with 1:10 and 1:1 ratios. The prepared polymersomal combinational formulation surrounded by hyaluronic acid brush as hydrophilic segment, could provide active targeting of the system against CD44 marker expressed on the surface of cancerous cells. The hyaluronic acid shell could also provide flexible chemistry for the conjugation of therapeutic FOXM1-specific DNA aptamer (Forkhead Box M1; against transcription factor FOXM1) on the surface of polymersomes in order to further suppress cancerous cell proliferation. The obtained results demonstrated that the prepared co-formulation provided sustained, controlled release of the entrapped drugs during 200 h. In vitro cytotoxicity experiments on non-small cell lung cancer, A549 and SK-MES-1 cell lines, demonstrated that the co-formulation of DOX and CPT provided synergistic effect and significantly higher cytotoxicity in comparison with free drugs. The cytotoxicity experiment also indicated that the aptamer conjugation on the co-formulations surface could significantly increase the cytotoxicity and induce apoptosis in combination therapy on both A549 and SK-MES-1 cell lines while aptamer-conjugated blank NPs did not show any cytotoxicity which emphasizes on the sensitization capability of the FOXM1 DNA aptamer against non-small cell lung cancer. Furthermore, it was shown that the co-formulation with or without aptamer renders the formulation specific tumor accumulation in vivo 24 h post-administration, assisting the combination synergy observed in vitro to be translated to in vivo antitumor efficacy. This combinatorial delivery platform strongly offers a novel approach for the synergistic controlled transportation of several chemotherapeutics for the treatment of non-small cell lung cancer.

Nano-realgar suppresses lung cancer stem cell growth by repressing metabolic reprogramming

BACKGROUND

Recent studies in cancer biology suggest that metabolic glucose reprogramming is a potential target for cancer treatment. However, little is known about drug intervention in the glucose metabolism of cancer stem cells (CSCs) and its related underlying mechanisms.

METHODS

The crude realgar powder was Nano-grinded to meets the requirements of Nano-pharmaceutical preparations, and Nano-realgar solution (NRS) was prepared for subsequent experiments. Isolation and characterization of lung cancer stem cells (LCSCs) was performed by magnetic cell sorting (MACS) and immunocytochemistry, respectively. Cell viability and intracellular glucose concentration were detected by MTT assay and glucose oxidase (GOD) kit. Protein expressions related to metabolic reprogramming was detected by ELISA assay. Determination of the expression of HIF-1α and PI3K/Akt/mTOR pathways was carried out by RT-PCR and western blotting analysis. A subcutaneous tumor model in BALB/c-nu mice was successfully established to evaluate the effects of Nano-realgar on tumor growth and histological structure, and the expression of HIF-1α in tumor tissues was measured by immunofluorescence.

RESULTS

Nano-realgar inhibits cell viability and induces glucose metabolism in LCSCs, and inhibits protein expression related to metabolic reprogramming in a time- and dose-dependent manner. Nano-realgar downregulated the expression of HIF-1α and PI3K/Akt/mTOR pathways in vitro and in vivo. Nano-realgar inhibits tumor growth and changes the histological structure of tumors through in vivo experiments and consequently inhibits the constitutive activation of HIF-1α signaling.

CONCLUSIONS

These results reveal that Nano-realgar inhibits tumor growth in vitro and in vivo by repressing metabolic reprogramming. This inhibitory effect potentially related to the downregulation HIF-1α expression via PI3K/Akt/mTOR pathway.

Lung cancer and epithelial-mesenchymal transition

Lung cancer (LC) is a leading cause of cancer-related death worldwide. Epithelial-mesenchymal transition (EMT) is a well-known phenomenon that promotes the invasive and metastatic capabilities of LC. Especially, EMT is assumed to be a pivotal mechanism for tumor cell invasion and metastasis, thereby limiting the efficacy of surgery and medical treatments, resulting in poor patient prognoses. Thus, the elucidation and reversal of EMT could provide changes in therapeutic strategies for LC. To overcome the limitations of currents treatment regimens for LC, it is important for surgeons to be familiar with this complex tumor characteristic. In this review, the activating signaling pathways underlying EMT and the associated tumor phenotypes are briefly described.

The metastasizing mechanisms of lung cancer: Recent advances and therapeutic challenges

Lung cancer is one of the common malignant tumors that threaten human life with serious incidence and high mortality. According to the histopathological characteristics, lung cancer is mainly divided into non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC accounts for about 80-85% of lung cancers. In fact, lung cancer metastasis is a major cause of treatment failure in clinical patients. The underlying reason is that the mechanisms of lung cancer metastasis are still not fully understood. The metastasis of lung cancer cells is controlled by many factors, including the interaction of various components in the lung cancer microenvironment, epithelial-mesenchymal transition (EMT) transformation, and metastasis of cancer cells through blood vessels and lymphatics. The molecular relationships are even more intricate. Further study on the mechanisms of lung cancer metastasis and in search of effective therapeutic targets can bring more reference directions for clinical drug research and development. This paper focuses on the factors affecting lung cancer metastasis and connects with related molecular mechanisms of the lung cancer metastasis and mechanisms of lung cancer to specific organs, which mainly reviews the latest research progress of NSCLC metastasis. Besides, in this paper, experimental models of lung cancer and metastasis, mechanisms in SCLC transfer and the challenges about clinical management of lung cancer are also discussed. The review is intended to provide reference value for the future research in this field and promising treatment clues for clinical patients.

CD44, a marker of cancer stem cells, is positively correlated with PD-L1 expression and immune cells infiltration in lung adenocarcinoma

Background

PD-L1 inhibitors is widely applied in lung adenocarcinoma patients. Tumor cells with high PD-L1 expression could trigger immune evasion. Cancer stem cells (CSCs) can evade from immunesurveillance due to their immunomodulating effects. However, the correlation between CSC and PD-L1 and some immune-related markers is seldom reported in patients with lung adenocarcinoma. Therefore, we aimed to ascertain their association in lung adenocarcinoma patients.

Methods

We assessed CD44 expression and its association with PD-L1 in lung adenocarcinoma, using Tumor Immune Estimation Resource (TIMER), which was further validated in our patient cohort. The immune cells infiltration was depicted by CIBERSORT using GEO database. The correlation between CD44 and immune cells was also analyzed. We further evaluated the prognostic role of CD44 in patients with lung adenocarcinoma both using Kaplan–Meier plotter and validated in our patient cohort.

Results

Positive association between CD44 and PD-L1 were found in lung adenocarcinoma patients. T cells CD4 memory resting cells and mast cells resting cells varied significantly between patients with CD44 high and those with CD44 low. Furthermore, positive association could be found between CD44 expression and immune cells. Arm-level depletion of CD44 was linked with B cell, CD4⁺ T cell, neutrophil and dendritic cell infiltration. Patients with higher CD44 levels had worsened overall survival (OS).

Conclusions

In summary, these results demonstrate that CD44 was associated with PD-L1 and infiltration of immune cells, and was a negative prognostic factor for predicting worsened OS in lung adenocarcinoma.

Genistein inhibits lung cancer cell stem-like characteristics by modulating MnSOD and FoxM1 expression

Manganese superoxide dismutase (MnSOD) promotes invasive and migratory activities by upregulating Forkhead box protein M1 (FoxM1) expression. The present study investigated whether modulation of MnSOD and FoxM1 expression was responsible for the antitumor effects of genistein on cancer stem-like cells (CSLCs) derived from non-small cell lung cancer cells (NSCLCs). Spheroids prepared from H460 or A549 cells were defined as lung cancer stem-like cells (LCSLCs) and were treated with genistein. The Cell Counting Kit-8 assay was performed to assess human lung fibroblast IMR-90 cell proliferation, as well as NSCLC H460 and A549 cell proliferation following treatment with genistein. MnSOD, FoxM1, cluster of differentiation (CD)133, CD44, BMI1 proto-oncogene, polycomb ring finger (Bmi1) and Nanog homeobox (Nanog) protein expression levels were examined via western blotting. The sphere formation assay was conducted to evaluate LCSLC self-renewal potential, and LSCLC migratory and invasive activities were analyzed using the wound healing and Transwell invasion assays, respectively. Knockdown and overexpression of MnSOD and FOXM1 via short hairpin-RNA or cDNA transfection were performed. The results indicated that genistein (80 and 100 µM) suppressed H460 and A549 cell viability compared with IMR-90 cells. Sub-cytotoxic concentrations of genistein (20 and 40 µM) inhibited sphere formation activity and decreased the protein expression levels of CD133, CD44, Bmi1 and Nanog in LCSLCs compared with the control group. Genistein also suppressed the migratory and invasive activities of LCSLCs compared with the control group. MnSOD and FoxM1 overexpression antagonized the effects of genistein (40 µM), whereas MnSOD and FoxM1 knockdown enhanced the inhibitory effects of genistein (20 µM) on CSLC characteristics of LCSLCs. Overall, the results suggested that genistein suppressed lung cancer cell CSLC characteristics by modulating MnSOD and FoxM1 expression levels.

Cancer Stem Cells-Origins and Biomarkers: Perspectives for Targeted Personalized Therapies

The use of biomarkers in diagnosis, therapy and prognosis has gained increasing interest over the last decades. In particular, the analysis of biomarkers in cancer patients within the pre- and post-therapeutic period is required to identify several types of cells, which carry a risk for a disease progression and subsequent post-therapeutic relapse. Cancer stem cells (CSCs) are a subpopulation of tumor cells that can drive tumor initiation and can cause relapses. At the time point of tumor initiation, CSCs originate from either differentiated cells or adult tissue resident stem cells. Due to their importance, several biomarkers that characterize CSCs have been identified and correlated to diagnosis, therapy and prognosis. However, CSCs have been shown to display a high plasticity, which changes their phenotypic and functional appearance. Such changes are induced by chemo- and radiotherapeutics as well as senescent tumor cells, which cause alterations in the tumor microenvironment. Induction of senescence causes tumor shrinkage by modulating an anti-tumorigenic environment in which tumor cells undergo growth arrest and immune cells are attracted. Besides these positive effects after therapy, senescence can also have negative effects displayed post-therapeutically. These unfavorable effects can directly promote cancer stemness by increasing CSC plasticity phenotypes, by activating stemness pathways in non-CSCs, as well as by promoting senescence escape and subsequent activation of stemness pathways. At the end, all these effects can lead to tumor relapse and metastasis. This review provides an overview of the most frequently used CSC markers and their implementation as biomarkers by focussing on deadliest solid (lung, stomach, liver, breast and colorectal cancers) and hematological (acute myeloid leukemia, chronic myeloid leukemia) cancers. Furthermore, it gives examples on how the CSC markers might be influenced by therapeutics, such as chemo- and radiotherapy, and the tumor microenvironment. It points out, that it is crucial to identify and monitor residual CSCs, senescent tumor cells, and the pro-tumorigenic senescence-associated secretory phenotype in a therapy follow-up using specific biomarkers. As a future perspective, a targeted immune-mediated strategy using chimeric antigen receptor based approaches for the removal of remaining chemotherapy-resistant cells as well as CSCs in a personalized therapeutic approach are discussed.

Twist3 is required for dedifferentiation during extraocular muscle regeneration in adult zebrafish

Severely damaged adult zebrafish extraocular muscles (EOMs) regenerate through dedifferentiation of residual myocytes involving a muscle-to-mesenchyme transition. Members of the Twist family of basic helix-loop-helix transcription factors (TFs) are key regulators of the epithelial-mesenchymal transition (EMT) and are also involved in craniofacial development in humans and animal models. During zebrafish embryogenesis, twist family members (twist1a, twist1b, twist2, and twist3) function to regulate craniofacial skeletal development. Because of their roles as master regulators of stem cell biology, we hypothesized that twist TFs regulate adult EOM repair and regeneration. In this study, utilizing an adult zebrafish EOM regeneration model, we demonstrate that inhibiting twist3 function using translation-blocking morpholino oligonucleotides (MOs) impairs muscle regeneration by reducing myocyte dedifferentiation and proliferation in the regenerating muscle. This supports our hypothesis that twist TFs are involved in the early steps of dedifferentiation and highlights the importance of twist3 during EOM regeneration.

Sevoflurane Inhibits Proliferation, Invasion, but Enhances Apoptosis of Lung Cancer Cells by Wnt/β-catenin Signaling via Regulating lncRNA PCAT6/miR-326 Axis

Sevoflurane was frequently used as a volatile anesthetic in cancer surgery. However, the potential mechanism of sevoflurane on lung cancer remains largely unclear. In this study, lung cancer cell lines (H446 and H1975) were treated by various concentrations of sevoflurane. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assessment and colony formation assay were performed to detect the cell viability and proliferation, separately. Also, transwell assay or flow cytometry assay was applied as well to evaluate the invasive ability or apoptosis in lung cancer cells, respectively. Western blot assay was employed to detect the protein levels of β-catenin and Wnt5a. Moreover, quantitative real-time polymerase chain reaction (qRT-PCR) was used to examine the expression level of prostate cancer-associated transcript 6 (PCAT6) and miR-326 in lung cancer tissues and cells. The target interaction between miR-326 and PCAT6 or Wnt5a was predicted by bioinformatics analysis and verified by the dual-luciferase reporter gene assay. Sevoflurane inhibited the abilities on viability, proliferation, invasion, and activation of Wnt/β-catenin signaling, but promoted apoptosis of H446 and H1975 cells in a dose-dependent manner. The expression of PCAT6 was increased in lung cancer tissues and cells, except for that of miR-326. Besides, sevoflurane could lead to expressed limitation of PCAT6 or improvement of miR-326. This process presented a stepwise manner. Up-regulation of PCAT6 restored the suppression of sevoflurane on abilities of proliferation, invasion, rather than apoptosis, and re-activated the Wnt5a/β-catenin signaling in cells. Moreover, the putative binding sites between miR-326 and PCTA6 or Wnt5a were predicted by starBase v2.0 software online. PCAT6 suppressing effects on cells could be reversed by pre-treatment with miR-326 vector. The promotion of Wnt5a inverted effects led from miR-326 or sevoflurane. Our study indicated that sevoflurane inhibited the proliferation, and invasion, but enhanced the apoptosis in lung cancer cells by regulating the lncRNA PCAT6/miR-326/Wnt5a/β-catenin axis.

Ancient Chinese Medicine Herbal Formula Huanglian Jiedu Decoction as a Neoadjuvant Treatment of Chemotherapy by Improving Diarrhea and Tumor Response

Background

Diarrhea is a major gastrointestinal complication in cancer patients receiving chemotherapy. Prognosis and treatment of chemotherapy-induced diarrhea (CID) remain unsatisfactory. This study aims to explore the potential of an ancient Chinese Medicine herbal formula Huanglian Jiedu Decoction (HLJDD) as an adjuvant treatment on CID.

Method

HLJDD extract was prepared by GMP manufacturing standard with quality and stability being checked. 5-fluorouracil (5-Fu) and irinotecan (CPT-11)-induced diarrhea model in mice was established and pre-, co- and post-treatment of HLJDD was implemented. Mechanism of action was explored by detecting related protein expression. In addition, the effect of HLJDD on diarrhea and tumor response induced by clinical regimens FOLFOX and FOLFIRI was measured in murine orthotopic colorectal cancer model.

Results

HLJDD exhibited consistency in quality and stability after 24-month storage. Pre-treatment of HLJDD, but not co-treatment or post-treatment, could significantly improve the diarrhea score, body weight loss and intestinal damage in 5-Fu- and CPT-11-treated mice. Pre-treatment of HLJDD reduced cell apoptosis in the intestine of chemotherapy-treated mice, and promoted renewal of intestinal cell wall. CD44 was predicted as the potential target of HLJDD-containing compounds in CID. HLJDD pre-treatment induced presentation of CD44-postive cells in the intestine of chemotherapy-treated mice, and initiated expression of stemness-associated genes. Transcriptional products of the downstream Wnt signaling of CD44 were elevated. Furthermore, pre-treatment of HLJDD could significantly improve the tumor response of clinical chemotherapy regimens FOLFOX and FOLFIRI in orthotopic colorectal cancer, and reduce diarrhea and intestinal damage. Conclusion: Our study suggests the potential of HLJDD as a neoadjuvant treatment of chemotherapy by reducing diarrhea and improving tumor response.

Nm23-H1 inhibits hypoxia induced epithelial-mesenchymal transition and stemness in non-small cell lung cancer cells

The Nm23 gene has been acknowledged to play a crucial role in lung cancer metastasis inhibitory cascades controlled by multiple factors. Low expression or allelic deletion of nm23-H1 is strongly linked to widespread metastasis and poor differentiation of non-small cell lung cancer (NSCLC). In this study, nm23-H1 was down regulated in epithelial-mesenchymal transition (EMT) and stemness enhancement under cobalt chloride (CoCl2)-induced hypoxia in NSCLC cells. Moreover, knocking down of nm23-H1 by shRNA apparently promoted hypoxia induced EMT and stemness, which was entirely suppressed via over expression of nm23-H1. Mechanistically, the Wnt/β-catenin signaling pathway was found to participate in the nm23-H1-mediated process. Besides, XAV939 prohibited cell EMT and stemness which could be impaired by knocking down of nm23-H1, while stable transfection of nm23-H1 attenuated hypoxia phonotype induced by lithium chloride (LiCl). Generally, our experiment provided evidence that nm23-H1 can reverse hypoxia induced EMT and stemness through the inhibition of the Wnt/β-catenin pathway, which may furnish a deeper perspective into the better treatment or prognosis for NSCLC.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.

Active PLK1-driven metastasis is amplified by TGF-β signaling that forms a positive feedback loop in non-small cell lung cancer

Early findings that PLK1 is highly expressed in cancer have driven an exploration of its functions in metastasis. However, whether PLK1 induces metastasis in vivo and its underlying mechanisms in NSCLC have not yet been determined. Here, we show that the expression of active PLK1 phosphorylated at T210, abundant in TGF-β-treated lung cells, potently induced metastasis in a tail-vein injection model. Active PLK1 with intact polo-box and ATP-binding domains accelerated cell motility and invasiveness by triggering EMT reprogramming, whereas a phosphomimetic version of p-S137-PLK1 did not, indicating that the phosphorylation status of PLK1 may determine the cell traits. Active PLK1-driven invasiveness upregulated TGF-β signaling and TSG6 encoded by TNFAIP6. Loss of TNFAIP6 disturbed the metastatic activity induced by active PLK1 or TGF-β. Clinical relevance shows that PLK1 and TNFAIP6 are strong predictors of poor survival rates in metastatic NSCLC patients. Therefore, we suggest that active PLK1 promotes metastasis by upregulating TGF-β signaling, which amplifies its metastatic properties by forming a positive feedback loop and that the PLK1/TGF-β-driven metastasis is effectively blocked by targeting PLK1 and TSG6, providing PLK1 and TSG6 as negative markers for prognostics and therapeutic targets in metastatic NSCLC.

Hyaluronan-CD44 axis orchestrates cancer stem cell functions

The prominent role of CD44 in tumor cell signaling together with its establishment as a cancer stem cell (CSC) marker for various tumor entities imply a key role for CD44 in CSC functional properties. Hyaluronan, the main ligand of CD44, is a major constituent of CSC niche and, therefore, the hyaluronan-CD44 signaling axis is of functional importance in this special microenvironment. This review aims to provide recent advances in the importance of hyaluronan-CD44 interactions in the acquisition and maintenance of a CSC phenotype. Hyaluronan-CD44 axis has a substantial impact on stemness properties of CSCs and drug resistance through induction of EMT program, oxidative stress resistance, secretion of extracellular vesicles/exosomes and epigenetic control. Potential therapeutic approaches targeting CSCs based on the hyaluronan-CD44 axis are also presented.

Downregulation of FOXO3a by DNMT1 promotes breast cancer stem cell properties and tumorigenesis

Breast cancer stem cells (BCSCs) are tumor initiating cells that can self-renew and are highly tumorigenic and chemoresistant. Therefore, the identification of factors critical for BCSC function is vital for the development of therapies. Here, we report that DNMT1-mediated FOXO3a promoter hypermethylation leads to downregulation of FOXO3a expression in breast cancer. FOXO3a is functionally related to the inhibition of FOXM1/SOX2 signaling and to the consequent suppression of BCSCs properties and tumorigenicity. Moreover, we found that SOX2 directly transactivates DNMT1 expression and thereby alters the methylation landscape, which in turn feedback inhibits FOXO3a expression. Inhibition of DNMT activity suppressed tumor growth via regulation of FOXO3a/FOXM1/SOX2 signaling in breast cancer. Clinically, we observed a significant inverse correlation between FOXO3a and FOXM1/SOX2/DNMT1 expression levels, and loss of FOXO3a expression or increased expression of FOXM1, SOX2, and DNMT1 predicted poor prognosis in breast cancer. Collectively, our findings suggest an important role of the DNMT1/FOXO3a/FOXM1/SOX2 pathway in regulating BCSCs properties, suggesting potential therapeutic targets for breast cancer.

KIAA0101 is a novel transcriptional target of FoxM1 and is involved in the regulation of hepatocellular carcinoma microvascular invasion by regulating epithelial-mesenchymal transition

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths due to tumor invasiveness, frequent intrahepatic dissemination and extrahepatic metastasis. However, the genes and signaling pathways that are involved remain incompletely understood. In this study, weighted gene coexpression network analysis (WGCNA) was performed to jointly analyze clinical information and gene expression data to identify key genes associated with clinical features. Through the bioinformatic analysis, the yellow module and microvascular invasion (MVI) were found to be highly associated (r=0.41) by Pearson's correlation analysis, and 20 hub genes were identified with both high gene significance (GS) and high module membership (MM) in the yellow module. Among these genes, FoxM1 and KIAA0101 were upregulated in HCC with MVI and were significantly positively correlated in HCC samples, indicating a novel regulatory network in HCC microvascular invasion. Moreover, in vitro experiments demonstrated that KIAA0101 is a direct target of FoxM1 and that KIAA0101 is required for the FoxM1-induced promotion of HCC cell invasion and migration. In addition, the FoxM1-KIAA0101 axis promotes HCC metastasis by inducing epithelial-mesenchymal transition (EMT). In summary, KIAA0101 is a novel target of FoxM1 and contributes to HCC metastasis by activating EMT. The FoxM1-KIAA0101 axis might be applied as a potential prognostic biomarker and therapeutic target for HCC.

A novel bispecific c-MET/CTLA-4 antibody targetting lung cancer stem cell-like cells with therapeutic potential in human non-small-cell lung cancer

A novel paradigm in tumor biology suggests that non-small-cell lung cancer (NSCLC) growth is driven by lung cancer stem cell (LCSC) like cells, but t here are still not any effective strategies to remove LCSCs. The bispecific antibody (BsAb) is a novel antibody, which can target two different antigens and mediate specific killing effects by selectively redirecting effector cells to the target cells. Here, we designed and synthesized a new BsAb, BsAb-5, that can target cellular mesenchymal-to-epithelial transition factor (c-MET) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) in CD166⁺ LCSCs with high affinity and specificity, for the first time. We showed that BsAb-5 could inhibit hepatocyte growth factor (HGF) mediated tumor development, including proliferation, migration, and apoptosis, serving as an inhibitory c-MET antibody. Moreover, we demonstrated that mechanisms responsible for BsAb-5 in CD166⁺ LCSCs included inducing c-MET degradation and inhibition of HGF-stimulated c-MET-Notch pathway by using AdHGF infection, nuclei location, and Western blot assays. In vivo, xenograft analysis revealed that mice on BsAb-5 group showed significantly reduced tumor volume. At the meantime, the observed antitumor effects of BsAb-5 were dependent on considerably suppressing T-regulatory cells (T_regs) and up-regulating effector T cells. On the basis of these results, we have identified a potential BsAb drug, which can effectively target c-MET and CTLA-4 in CD166⁺ LCSCs for the treatment of human NSCLC.

Correlated low IGF2BP1 and FOXM1 expression predicts a good prognosis in lung adenocarcinoma

IGF2BP1 and FOXM1 are shown to be critical in the regulation of caner progression. However, the prognostic value of IGF2BP1 in lung adenocarcinoma and its relationship with FOXM1 still remains unclear. In this study, the expression and biological significance of both IGF2BP1 and FOXM1 were evaluated in 188 lung adenocarcinoma, at mRNA and protein levels. We showed that mRNA and protein levels of IGF2BP1 and FOXM1 were upregulated in lung adenocarcinoma compared to adjacent non-cancerous tissues. High IGF2BP1 expression was correlated with a poor prognosis for lung adenocarcinoma patients. Moreover, IGF2BP1 expression was positively associated with FOXM1 expression. Meanwhile, the findings indicated that low IGF2BP1 combined with low FOXM1 expression, was negatively correlated with pathological stage and lymph node metastasis, predicted good outcomes for lung adenocarcinoma patients. Additionally, low IGF2BP1 and FOXM1 expression status, is an independent prognostic factor for lung adenocarcinoma after surgical resection. We demonstrate that low IGF2BP1 and FOXM1 expression can serve as a potential factor for the clinical diagnosis and prognosis of lung adenocarcinoma, and targeted inhibition of IGF2BP1 and FOXM1 might be an alternative strategy for the management of lung adenocarcinoma.

The multifaceted roles of FOXM1 in pulmonary disease

Forkhead box M1 (FOXM1), a transcriptional regulator of G1/S and G2/M transition and M phase progression in the cell cycle, plays a principal role in many physiological and pathological processes. A growing number of studies have focused on the relationship between abnormal FOXM1 expression and pulmonary diseases, such as lung cancer, chronic obstructive pulmonary disease (COPD), asthma, acute lung injury (ALI), pulmonary fibrosis, and pulmonary arterial hypertension (PAH). These studies indicate that the FOXM1 regulatory network is a major predictor of poor outcomes, especially in lung cancer, and provide novel insight into various pulmonary diseases. For the first time, this review summarizes the mechanistic relationship between FOXM1 dysregulation and pulmonary diseases, the benefits of targeting abnormal FOXM1 expression, and the questions that remain to be addressed in the future.

The subpopulation of CD44-positive cells promoted tumorigenicity and metastatic ability in lung adenocarcinoma

BACKGROUND

Lung cancer is one of the major causes of carcinoma-related deaths in the world. Importantly, lung adenocarcinoma (LAC) is the most common type with poor outcome. However, the progressive clinical phenotype and biomolecular signature of lung cancer presenting the cancer stem-like and metastatic characteristics are still unclear.

METHODS

In this study, we identified CD44 marker in lung cancers. The capabilities, including tumorigenic and migration assays, were analyzed in CD44 expression and CD44 expression subgroups. Meanwhile, the potential bio-signature and properties of lung tumor stem-like cells were further studied.

RESULTS

The high expression of CD44 subpopulation (CD44-positive) in isolated lung cancer cells showed significantly higher abilities of tumorigenic colonies, tumor-sphere formation, and migratory properties when compared with the CD44 expression group. These subgroups of CD44-positive lung cancer cells further demonstrated the metastatic potential with epithelial-mesenchymal transition (EMT), as well as the high expression of Twist and Snail gene profile. Importantly, the overexpression of Snail with gene vector in CD44 expression cells further significantly promoted the properties of lung tumor stem-like cells.

CONCLUSION

The results of this study highlighted the role of CD44-posivite subpopulation in modulating tumor initiation and EMT-based metastatic ability of lung malignancy.

Villi development core-related gene expression associated with lung squamous cancer prognosis

Similarities between embryonic development and tumorigenesis are reflected in biological behavior and gene expression. Although the gene signature during development and the clinical phenotype of different cancers show certain correlation pattern, the correlation between early embryo development and cancer remains largely unexplored. To compare the gene expression profile between development and cancer, our study analyzed the gene expression of chorionic villi samples at different gestational ages (6, 7, 8, 9, 10, 40 weeks) obtained from gene expression omnibus (GEO) datasets using correlation test. Then the villi development-related genes that gradually showed a positive correlation (upregulated) (n = 394) or negative correlation (downregulated) (n = 325) with time were used to construct protein-protein interaction (PPI) networks. Three subnetworks among the gradually upregulated genes and 3 subnetworks among the downregulated genes were identified using the molecular complex detection (MCODE) plugin in Cytoscape software. The most significant GO terms for villi-correlated genes were immune, inflammatory response and cell division. These gene clusters were also dysregulated in lung squamous cell carcinoma (SCC). Moreover the prognostic value of the gene clusters was then analyzed with TCGA lung SCC data, which showed 4 clusters that were associated with prognosis. Our results demonstrate the gene expression similarity between development and lung SCC and identified development-associated gene clusters that could contain prognostic information for lung SCC patients.

Fisetin suppresses migration, invasion and stem-cell-like phenotype of human non-small cell lung carcinoma cells via attenuation of epithelial to mesenchymal transition

Fisetin (3,3',4',7-tetrahydroxyflavone) is a bioactive polyphenolic flavonoid found in many fruits and vegetables. It exhibits a variety of pharmacological activities including anticancer and anti-invasive effects. Epithelial to mesenchymal transition (EMT) allows the tumor cells to acquire increased migratory and invasive properties mediating their dissemination to faraway sites, thus favoring metastasis. With metastatic lung cancer claiming the majority of lung cancer-related deaths, agents targeting the pathways underlying metastasis are translationally promising. In the present study, we have explored the anti-metastatic effects of fisetin in non-small cell lung carcinoma (NSCLC) cells A549 and H1299 with emphasis on EMT. The results suggested a significant inhibition in migration and invasion of NSCLC cells under non-cytotoxic concentrations. Furthermore, an attenuation of the EMT was observed in both the cell lines with upregulation in the expression of epithelial marker E-cadherin in A549 cells and ZO-1 in H1299 cells with concomitant downregulation of the mesenchymal markers vimentin as well as N-cadherin along with invasion marker MMP-2. Herein, the downregulation of the expression of NSCLC stem cell signature markers CD44 and CD133 was also observed. Fisetin decreased the expression of multiple signaling proteins (β-catenin, NF-κB, EGFR, STAT-3) acting upstream to EMT and known to be involved in induction and maintenance of mesenchymal phenotype, which may explain the observed effects. Moreover, fisetin decreased the ability of H1299 cells to form colonies on soft agar and potentiated the cytotoxic effects of tyrosine kinase inhibitor (TKI), erlotinib. Overall, our study suggested the ability of fisetin to serve as a potential therapeutic agent on its capacity to attenuate the EMT program and inhibit migration, invasion and stem cell phenotype of lung cancer cells.

Prevention of breast cancer by dietary polyphenols-role of cancer stem cells

Breast cancer is a common malignancy with poor prognosis. Cancer cells are heterogeneous and cancer stem cells (CSCs) are primarily responsible for tumor relapse, treatment-resistance and metastasis, so for breast cancer stem cells (BCSCs). Diets are known to be associated with carcinogenesis. Food-derived polyphenols are able to attenuate the formation and virulence of BCSCs, implying that these compounds and their analogs might be promising agents for preventing breast cancer. In the present review, we summarized the origin and surface markers of BCSCs and possible mechanisms responsible for the inhibitory effects of polyphenols on BCSCs. The suppressive effects of common dietary polyphenols against BCSCs, such as curcumin, epigallocatechin gallate (EGCG) and related polyphenolic compounds were further discussed.

Lung cancer stem cells: origin, features, maintenance mechanisms and therapeutic targeting

Lung cancer remains the leading cause of cancer-related deaths despite recent breakthroughs in immunotherapy. The widely embraced cancer stem cell (CSC) theory has also been applied for lung cancer, postulating that an often small proportion of tumor cells with stem cell properties are responsible for tumor growth, therapeutic resistance and metastasis. The identification of these CSCs and underlying molecular maintenance mechanisms is considered to be absolutely necessary for developing therapies for their riddance, hence achieving remission. In this review, we will critically address the CSC concept in lung cancer and its advancement thus far. We will describe both normal lung stem cells and their malignant counterparts in order to identify common aspects with respect to their emergence and regulation. Subsequently, the importance of CSCs and their molecular features in lung cancers will be discussed in a preclinical and clinical context. We will highlight some examples on how lung CSCs attain stemness through different molecular modifications and cellular assistance from the tumor microenvironment. The exploitation of these mechanistic features for the development of pharmacological therapy will also be discussed. In summary, the validity of the CSC concept has been evidenced by various studies. Ongoing research to identify molecular mechanisms driving lung CSC have revealed potential new cell intrinsic as well as tumor microenvironment-derived therapeutic targets. Although successfully demonstrated in preclinical models, the clinical benefit of lung CSC targeted therapies has thus far not been demonstrated. Therefore, further research to validate the therapeutic value of CSC concept is required.

The lncRNA MIR4435-2HG promotes lung cancer progression by activating β-catenin signalling

Recently, emerging evidence has suggested that long noncoding RNAs (lncRNAs) have crucial roles in cancer progression. Here, we demonstrated that the lncRNA MIR4435-2HG was highly expressed in lung cancer tissues and correlated with histological grades and lymph node metastasis. Phenotypic analysis indicated that MIR4435-2HG knockdown inhibited lung cancer cell proliferation and invasion in vitro and in vivo. Notably, MIR4435-2HG knockdown suppressed the EMT (epithelial-mesenchymal transition) process and cancer stem cell traits of lung cancer cells. Mechanistically, MIR4435-2HG knockdown decreased the transactivation of β-catenin. MIR4435-2HG interacted with β-catenin and thus prevented its degradation by the proteasome system. Our findings highlight the important roles and mechanisms of MIR4435-2HG in lung cancer progression. High expression of lncRNA MIR4435-2HG correlates with lung cancer progression MIR4435-2HG promotes lung cancer cells proliferation and invasion MIR4435-2HG knockdown suppresses the EMT process and cancer stem cell traits MIR4435-2HG knockdown inhibits the β-catenin signalling.

Novel triple‑positive markers identified in human non‑small cell lung cancer cell line with chemotherapy-resistant and putative cancer stem cell characteristics

Through the specific identification and direct targeting of cancer stem cells (CSCs), it is believed that a better treatment efficacy of cancer may be achieved. Hence, the present study aimed to identify a CSC subpopulation from adenocarcinoma cells (A549) as a model of non-small cell lung cancer (NSCLC). Initially, we sorted two subpopulations known as the triple-positive (EpCAM⁺/CD166⁺/CD44⁺) and triple-negative (EpCAM⁻/CD166⁻/CD44⁻) subpopulation using fluorescence-activated cell sorting (FACS). Sorted cells were subsequently evaluated for proliferation and chemotherapy-resistance using a viability assay and were further characterized for their clonal heterogeneity, self-renewal characteristics, cellular migration, alkaline dehydrogenase (ALDH) activity and the expression of stemness-related genes. According to our findings the triple-positive subpopulation revealed significantly higher (P<0.01) proliferation activity, exhibited better clonogenicity, was mostly comprised of holoclones and had markedly bigger (P<0.001) spheroid formation indicating a better self-renewal capacity. A relatively higher resistance to both 5-fluouracil and cisplatin with 80% expression of ALDH was observed in the triple-positive subpopulation, compared to only 67% detected in the triple-negative subpopulation indicated that high ALDH activity contributed to greater chemotherapy-resistance characteristics. Higher percentage of migrated cells was observed in the triple-positive subpopulation with 56% cellular migration being detected, compared to only 19% in the triple-negative subpopulation on day 2. This was similarly observed on day 3 in the triple-positive subpopulation with 36% higher cellular migration compared to the triple-negative subpopulation. Consistently, elevated levels of the stem cell genes such as REX1 and SSEA4 were also found in the triple-positive subpopulation indicating that the subpopulation displayed a strong characteristic of pluripotency. In conclusion, our study revealed that the triple-positive subpopulation demonstrated similar characteristics to CSCs compared to the triple-negative subpopulation. It also confirmed the feasibility of using the triple-positive (EpCAM⁺/CD166⁺/CD44⁺) marker as a novel candidate marker that may lead to the development of novel therapies targeting CSCs of NSCLC.

Lx2-32c inhibits the formation of mammosphere from MDA-MB-231 cells and induces apoptosis involving in down-regulating FoxM1

Cancer stem cells (CSCs) are a subset of cancer cells which have self-renewal ability and exist in various tumors. Inhibition of CSCs self-renewal is considered as a new method for tumor therapy. A novel semi-synthetic taxane analogue, Lx2-32c, could overcome drug resistance in various cancer cell lines. In this study, it was found that Lx2-32c inhibited the proliferation and mammosphere formation of MDA-MB-231-derived cancer stem cell-like cells (MCSCLCs) and induced apoptosis, as well as down-regulated the expression of FoxM1 and CD44 in MCSCLCs. Simultaneously, it was proved that Lx2-32c combined with thiostreption, a FoxM1 inhibitor inhibited proliferation and mammosphere formation of MCSCLCs and induced apoptosis to a more extent than Lx2-32c alone; thiostreption could also enhance the effect of Lx2-32c of reduction of the expression of FoxM1 and CD44. All of these results indicated that Lx2-32c is a novel semi-synthetic taxane analogue which inhibits the self-renewal of MCSCLCs cells and induces apoptosis involving in down-regulating FoxM1.

CD44 promotes cell proliferation in non-small cell lung cancer

Cluster of differentiation 44 (CD44), a marker for cancer stem cells, has been reported to be associated with poor prognosis in non-small cell lung cancer (NSCLC), but its involvement in tumor growth has not fully been elucidated. The present study explored the associations between CD44 expression and clinicopathological features using immunohistochemistry in 94 NSCLC cases, as well as proliferation in cells with aberrant expression of this protein. Overexpression of CD44 was achieved by transfecting H1299 cells with CD44 expression vectors, and inhibition of CD44 expression was performed by transfecting small interfering RNAs into A549 cells. Cell proliferation was measured using Cell Counting Kit-8 assays and flat plate colony formation assay was performed to confirm the cellular anchorage growth in vitro. In total, 64 (68.1%) of the 94 NSCLC cases stained positive for CD44 expression. High expression of CD44 was associated with advanced T stage in NSCLC. Overexpression of CD44 in H1299 cells promoted cell proliferation and colony formation in vitro. Meanwhile, knockdown of CD44 expression in A549 cells suppressed cell proliferation and colony formation in vitro. High expression of CD44 may promote NSCLC progression by increasing cancer cell proliferation; therefore, it may serve as a potential biomarker for diagnosis or target therapy.

CD44v6-competent tumor exosomes promote motility, invasion and cancer-initiating cell marker expression in pancreatic and colorectal cancer cells

Cancer-initiating cells (CIC) account for metastatic spread, which may rely mostly on CIC exosomes (TEX) that affect host cells and can transfer CIC features into Non-CIC. The CIC marker CD44 variant isoform v6 (CD44v6) being known for metastasis-promotion, we elaborated in cells its contribution to migration and invasion and in TEX the tranfer of migratory and invasive capacity to Non-CIC, using a CD44v6 knockdown (CD44v6kd) as Non-CIC model.A CD44v6kd in human pancreatic and colorectal cancer (PaCa, CoCa) lines led to loss of CIC characteristics including downregulation of additional CIC markers, particularly Tspan8. This aggravated the loss of CD44v6-promoted motility and invasion. Loss of motility relies on the distorted cooperation of CD44v6 and Tspan8 with associated integrins and loss of invasiveness on reduced protease expression. These deficits, transferred into TEX, severely altered the CD44v6kd-TEX composition. As a consequence, unlike the CIC-TEX, CD44v6kd TEX were not taken up by CD44v6kd cells and CIC. The uptake of CIC-TEX was accompanied by partial correction of CIC marker and protease expression in CD44v6kd cells, which regained migratory, invasive and metastatic competence. CIC-TEX also fostered angiogenesis and expansion of myeloid cells, likely due to a direct impact of CIC-TEX on the host, which could be supported by reprogrammed CD44v6kd cells.Taken together, the striking loss of tumor progression by a CD44v6kd relies on the capacity of CD44v6 to cooperate with associating integrins and proteases and its promotion of additional CIC marker expression. The defects by a CD44v6kd are efficiently corrected upon CIC-TEX uptake.

SLC34A2 regulates miR-25-Gsk3β signaling pathway to affect tumor progression in gastric cancer stem cell-like cells

A novel paradigm in tumor biology suggests that gastric cancer progression is driven by gastric cancer stem cell-like cells (GCSCs), but molecular mechanisms regulating tumorigenic and self-renewal potential of GCSCs are still unclear. Here, we aim to investigate biological function of SLC34A2 in regulating sphere formation and tumorigenicity (both are the hallmark of CSCs) of GCSCs and its underlying mechanisms. Our findings testified that CD44⁺ cells which were derived from fresh primary gastric cancer samples and cell lines displayed stem cell-like features. Significantly, SLC34A2 is increased in CD44⁺ GCSCs compared with those in adherent counterpart from CD44⁺ GCSCs. On clinic, SLC34A2 is overexpressed in primary tumor tissues compared with adjacent counterparts. We showed that SLC34A2 regulated sphere formation and self-renewal properties of CD44⁺ GCSCs in vitro and in vivo. Mechanistic investigations revealed that Gsk3β was the most strikingly up-regulated gene in response to SLC34A2 knockdown in GCSCs and Wnt/β-cantenin signaling was required for SLC34A2-mediated sphere formation. Furthermore, SLC34A2 directly binds specific sites in the miR-25 promoter region and that the promoter activity is decreased after the mutation of putative SLC34A2-binding sites, indicating that SLC34A2 is required for the transcriptional induction of miR-25. Meanwhile, luciferase assays showed that miR-25 directly targeted Gsk3β in CD44⁺ GCSCs. Overall, our findings define a SLC34A2-miR-25-Gsk3β pathway in the regulation of GCSCs features and gastric cancer progression, with potential therapeutic applications in blocking their progression.

Effects of Wnt-1 blockade in DEN-induced hepatocellular adenomas of mice

Recent evidence has suggested that downregulation of the Wnt/β-catenin signaling pathway may contribute to the development and growth of HCC. Consequently, elements of this pathway have begun to emerge as potential targets for improving outcomes of anti-HCC. Thus, the present study sought to examine the effects of Wnt-1 blockade using the classical diethylnitrosamine (DEN)-induced chemical carcinogenesis mouse model of HCC. The depletion of Wnt-1 using neutralizing antisera was done for ten consecutive days at the age of 9 months and mice were examined for the following 20 days. At that time, DEN-treated mice had multiple variably-sized hepatic cell adenomas. Anti-Wnt-1 was particularly potent in suppressing the expression of critical elements of the Wnt/β-catenin signaling pathway, such as β-catenin and Frizzled-1 receptor, however, not Dickkopf-related protein 1. This effect co-existed with the suppression of Cyclin D1, FOXM1, NF-κΒ and c-Jun commensurate with proliferation and apoptosis blockade in hepatocellular adenomas, and reduced Bcl-2 and c-Met in the serum of mice. Nonetheless, tumor size and multiplicity were found to be unaffected, suggesting that apoptosis may be equally important to proliferation in the context of counteracting DEN induced hepatocellular adenomas of mice.