The ERK-ZEB1 pathway mediates epithelial-mesenchymal transition in pemetrexed resistant lung cancer cells with suppression by vinca alkaloids

MTHFD2 marks pemetrexed resistance in pulmonary adenocarcinoma with EGFR wild type

PURPOSE

Lung cancer is the leading cause of cancer-related deaths worldwide. Patients with an amplification of the MTHFD2 gene have a particularly poor prognosis. MTHFD2 signaling has been associated with migration, metastasis, and proliferation of lung cancer cells mediated through ERK signaling. Although the enzymatic activity of the MTHFD2 protein is well understood, little is known about its larger role in chemoresistance.

METHODS

Seventy-nine of non-small cell lung cancer (NSCLC) samples with clinical follow-up were subjected to immunohistochemical staining for MTHFD2 and sequenced using next generation sequencing (NGS) to determine EGFR status. MTHFD2 gene was knocked down in two NSCLC cell lines with wild type EGFR gene (HCC44 and H1993) where MTHFD2 signaling and chemotherapy resistance against pemetrexed were evaluated.

RESULTS

MTHFD2 expression data revealed a strong prognosis relevance in adenocarcinoma (LUAD). Immunoblotting of cell lines showed a MTHFD2 dependent and cell type specific ERK signaling in EGFR wild type cells. MTHFD2 expression induced proliferation of NSCLC cells and their resistance against pemetrexed. Knocking down the MTHFD2 gene induced cycle arrest, however, it did not activate apoptosis signaling within HCC44 cell line.

CONCLUSIONS

MTHFD2 expression is strongly associated with prognosis in LUAD patients, as well as with increased cellular proliferation and resistance to pemetrexed in LUAD patients with wild-type EGFR. These findings suggest that MTHFD2 could serve as a valuable biomarker for predicting treatment outcomes in LUAD. Further studies are needed to fully explore the clinical implications and potential combination therapies targeting MTHFD2 in LUAD.

Traditional Chinese medicine in lung cancer treatment

Lung cancer remains a major global health challenge and one of the leading causes of cancer-related deaths worldwide. Despite significant advancements in treatment, challenges such as drug resistance, side effects, metastasis and recurrence continue to impact patient outcomes and quality of life. In response, there is growing interest in complementary and integrative approaches to cancer care. Traditional Chinese medicine (TCM), with its long history, abundant clinical experience, holistic perspective and individualized approach, has garnered increasing attention for its role in lung cancer prevention and management. This review provides a comprehensive overview of the advances in TCM for lung cancer treatment, covering its theoretical foundation, treatment principles, clinical experiences and evidence supporting its efficacy. We also provide a systematic summary of the preclinical mechanisms, through which TCM impacts lung cancer, including the induction of cell death, reversal of drug resistance, inhibition of metastasis and modulation of immune responses. Additionally, future prospects for TCM in lung cancer treatment are discussed, offering insights into its expanded application and integration with modern medicine to address this challenging disease.

Endoglin as a predictive biomarker for pemetrexed sensitivity in non-small-cell lung cancer: a cellular study

OBJECTIVE

Based on our previous research, which demonstrated that elevated plasma endoglin (ENG) levels in lung cancer patients were associated with a better prognosis, increased sensitivity to pemetrexed, and enhanced tumor suppression, this study aims to validate these findings at the cellular level. The focus is on membrane and extracellular ENG and their influence on drug response and tumor cell behavior in non-small cell lung cancer (NSCLC) cells.

METHODS

The correlation between ENG expression and pemetrexed-induced cytotoxicity in eight human non-squamous subtype NSCLC cell lines was analyzed. ENG in A549 and H1975 cells was knocked down using shRNA. MTT assay, cell cycle assay, western blot analysis, and boyden chamber assay were used to detect the effect of ENG on pemetrexed-induced cytotoxicity, cell cycle distribution, and cell migration.

RESULTS

The expression of membrane ENG was positively correlated with pemetrexed-induced cytotoxicity in human NSCLC cells. Compared to pemetrexed-sensitive A549 cells, the A549/a400 (pemetrexed-resistant subline) cells exhibited a reduced accumulation of cells in the S phase, making them less susceptible to cell death. ENG knockdown also alleviated pemetrexed-induced S phase arrest and regulated G1/S phase-related proteins (p53, p21, CDK2, and Cyclin A). Additionally, co-treatment with recombinant ENG enhanced pemetrexed-induced migration inhibition in the sensitive cel1 line and cytotoxicity in the resistance cell line.

CONCLUSION

The present results strengthened our prior clinical findings, showing that higher membrane ENG expression enhances pemetrexed-induced cytotoxicity and S phase arrest, which may involve the ENG-p21 pathway. Additionally, microenvironmental ENG enhanced the anti-migration of pemetrexed. These findings highlight the potential of ENG as a biomarker and therapeutic target, opening new avenues to improve the outcomes of non-squamous cell NSCLC treatment.

Anticancer Properties Against Select Cancer Cell Lines and Metabolomics Analysis of Tender Coconut Water

BACKGROUND

Tender Coconut Water (TCW) is a nutrient-rich dietary supplement that contains bioactive secondary metabolites and phytohormones with anti-oxidative and anti-inflammatory properties. Studies on TCW's anti-cancer properties are limited and the mechanism of its anti-cancer effects have not been defined.

OBJECTIVE

In the present study, we investigate TCW for its anti-cancer properties and, using untargeted metabolomics, we identify components form TCW with potential anti-cancer activity.

METHODOLOGY

Cell viability assay, BrdU incorporation assay, soft-agar assay, flow-cytometery, and Western blotting were used to analyze TCW's anticancer properties and to identify mechanism of action. Liquid chromatography- Tandem Mass Spectroscopy (LC-MS/MS) was used to identify TCW components.

RESULTS

TCW decreased the viability and anchorage-independent growth of HepG2 hepatocellular carcinoma (HCC) cells and caused S-phase cell cycle arrest. TCW inhibited AKT and ERK phosphorylation leading to reduced ZEB1 protein, increased E-cadherin, and reduced N-cadherin protein expression in HepG2 cells, thus reversing the 'epithelial-to-mesenchymal' (EMT) transition. TCW also decreased the viability of Hep3B hepatoma, HCT-15 colon, MCF-7 and T47D luminal A breast cancer (BC) and MDA-MB-231 and MDA-MB-468 triplenegative BC cells. Importantly, TCW did not inhibit the viability of MCF-10A normal breast epithelial cells. Untargeted metabolomics analysis of TCW identified 271 metabolites, primarily lipids and lipid-like molecules, phenylpropanoids and polyketides, and organic oxygen compounds. We demonstrate that three components from TCW: 3-hydroxy-1-(4-hydroxyphenyl)propan-1-one, iondole-3-carbox aldehyde and caffeic acid inhibit the growth of cancer cells.

CONCLUSION

TCW and its components exhibit anti-cancer effects. TCW inhibits the viability of HepG2 hepatocellular carcinoma cells by reversing the EMT process through inhibition of AKT and ERK signalling.

The signaling landscape of insulin-like growth factor 1

The sheer amplitude of biological actions of insulin-like growth factor I (IGF-1) affecting all types of cells in all tissues suggests a vast signaling landscape for this ubiquitous humoral signal. While the canonical signaling pathways primarily involve the Ras/MAPK and PI3K/AKT cascades, the evolutionary conservation of insulin-like peptides (ILPs) and their pathways hints at the potential for novel functions to emerge over time. Indeed, the evolutionary trajectory of ILPs opens the possibility of either novel functions for these two pathways, novel downstream routes, or both. Evidence supporting this notion includes observations of neofunctionalization in bony fishes or crustaceans, and the involvement of ILPs pathways in invertebrate eusociality or in vertebrate bone physiology, respectively. Such evolutionary processes likely contribute to the rich diversity of ILPs signaling observed today. Moreover, the interplay between conserved signaling pathways, such as those implicated in aging (predominantly involving the PI3K-AKT route), and lesser known pathways, such as those mediated by biased G-protein coupled receptors and others even less known, may underpin the context-dependent actions characteristic of ILPs signaling. While canonical IGF-1 signaling is often assumed to account for the intracellular pathways utilized by this growth factor, a comprehensive analysis of all the pathways mediated by the IGF-1 receptor (IGF-1R) remains lacking. This review aims to explore both canonical and non-canonical routes of IGF-1R action across various cell types, offering a detailed examination of the mechanisms underlying IGF-1 signaling and highlighting the significant gaps in our current understanding.

Role of microRNA-363 during tumor progression and invasion

Recent progresses in diagnostic and therapeutic methods have significantly improved prognosis in cancer patients. However, cancer is still considered as one of the main causes of human deaths in the world. Late diagnosis in advanced tumor stages can reduce the effectiveness of treatment methods and increase mortality rate of cancer patients. Therefore, investigating the molecular mechanisms of tumor progression can help to introduce the early diagnostic markers in these patients. MicroRNA (miRNAs) has an important role in regulation of pathophysiological cellular processes. Due to their high stability in body fluids, they are always used as the non-invasive markers in cancer patients. Since, miR-363 deregulation has been reported in a wide range of cancers, we discussed the role of miR-363 during tumor progression and metastasis. It has been reported that miR-363 has mainly a tumor suppressor function through the regulation of transcription factors, apoptosis, cell cycle, and structural proteins. MiR-363 also affected the tumor progression via regulation of various signaling pathways such as WNT, MAPK, TGF-β, NOTCH, and PI3K/AKT. Therefore, miR-363 can be introduced as a probable therapeutic target as well as a non-invasive diagnostic marker in cancer patients.

TPI1 promotes MAPK/ERK-induced EMT, cell migration and invasion in lung adenocarcinoma

BACKGROUND

Triosephosphate isomerase 1 (TPI1), as a widely involved glycolytic enzyme, plays a significant role in glucose metabolism and is highly expressed in various tumors. However, its role in lung adenocarcinoma (LUAD) remains incompletely understood.

METHODS

Through bioinformatic analysis, we identified a positive association between high expression of TPI1 and metastasis in LUAD. Western blot, RT-qPCR, wound healing assays and transwell experiments, were employed to investigate potential mechanisms.

RESULTS

In this study, bioinformatic analysis showed that high expression of TPI1 was associated with poor prognosis in LUAD patients. We examined the expression of TPI1 in 29 paired LUAD tissues and found that TPI1 expression was higher in LUAD tissues than in paired adjacent noncancerous tissues. Meanwhile, overexpression of TPI1 promoted the epithelial-mesenchymal transition (EMT) process in LUAD cells, while silencing TPI1 weakened the EMT process. Furthermore, TPI1 was shown to regulate EMT through the MAPK/ERK signaling pathway.

CONCLUSION

TPI1 promotes LUAD metastasis by activating the MAPK/ERK signaling pathway.

Extracellular Signal-Regulated Kinases: One Pathway, Multiple Fates

This comprehensive review delves into the multifaceted aspects of ERK signaling and the intricate mechanisms underlying distinct cellular fates. ERK1 and ERK2 (ERK) govern proliferation, transformation, epithelial-mesenchymal transition, differentiation, senescence, or cell death, contingent upon activation strength, duration, and context. The biochemical mechanisms underlying these outcomes are inadequately understood, shaped by signaling feedback and the spatial localization of ERK activation. Generally, ERK activation aligns with the Goldilocks principle in cell fate determination. Inadequate or excessive ERK activity hinders cell proliferation, while balanced activation promotes both cell proliferation and survival. Unraveling the intricacies of how the degree of ERK activation dictates cell fate requires deciphering mechanisms encompassing protein stability, transcription factors downstream of ERK, and the chromatin landscape.

Gemcitabine resistance in non-small cell lung cancer is mediated through activation of the PI3K/AKT/NF-κB pathway and suppression of ERK signaling by reactive oxygen species

Lung cancer is one of the most common cancers in the world. Chemotherapy is a standard clinical treatment. However, tumor cells often develop multidrug resistance after chemotherapy, an inevitable bottleneck in cancer treatment. Therefore, this study used gemcitabine-resistant (GEM-R) CL1-0 lung cancer cells. First, we used flow cytometry and western blot analysis to examine differences in performance between resistant and parental cells. The results showed that compared with parental cells, GEM-R CL1-0 cells significantly enhanced the activation of the AKT pathway, which promoted survival and growth, and decreased the activation of the reactive oxygen species-extracellular signal-regulated kinase (ROS)-ERK pathway. Next, the AKT and ERK pathways' role in tumor growth was further explored in vivo using a xenograft model. The results showed that enhancing AKT and inhibiting ERK activation reduced GEM-induced inhibition of tumor growth. Finally, combining the above results, we found that GEM-R CL1-0 cells showed reduced sensitivity to GEM by activating the phosphatidylinositol 3-kinase/AKT/NF-kB pathway and inhibiting the ROS-ERK pathway leading to resistance against GEM. Therefore, the AKT and ERK pathways are potential targets for improving the sensitivity of cancer cells to anticancer drugs.

Phosphorylation of Bcl-2 by JNK confers gemcitabine resistance in lung cancer cells by reducing autophagy-mediated cell death

The most common cancer-related death in the world is non-small cell lung cancer (NSCLC). Gemcitabine (GEM) is a common and effective first-line chemotherapeutic drug for the treatment of NSCLC. However, the long-term use of chemotherapeutic drugs in patients usually induces cancer cell drug resistance, leading to poor survival, and prognosis. In this study, to observe and explore the key targets and potential mechanisms of NSCLC resistance to GEM, we first cultured lung cancer CL1-0 cells in a GEM-containing medium to induce CL1-0 cells to develop GEM resistance. Next, we compared protein expression between the parental and GEM-R CL1-0 cell groups. We observed significantly lower expression of autophagy-related proteins in GEM-R CL1-0 cells than in parental CL1-0 cells, indicating that autophagy is associated with GEM resistance in CL1-0 cells. Furthermore, a series of autophagy experiments revealed that GEM-R CL1-0 cells had significantly reduced GEM-induced c-Jun N-terminal kinase phosphorylation, which further affected the phosphorylation of Bcl-2, thereby reducing the dissociation of Bcl-2 and Beclin-1 and ultimately reducing the generation of GEM-induced autophagy-dependent cell death. Our findings suggest that altering the expression of autophagy is a promising therapeutic option for drug-resistant lung cancer.

Cross-talk between non-ionizing electromagnetic fields and metastasis; EMT and hybrid E/M may explain the anticancer role of EMFs

Recent studies have shown that non-ionizing electromagnetic fields (NIEMFs) in a specific frequency, intensity, and exposure time can have anti-cancer effects on various cancer cells; however, the underlying precise mechanism of action is not transparent. Most cancer deaths are due to metastasis. This important phenomenon plays an inevitable role in different steps of cancer including progression and development. It has different stages including invasion, intravasation, migration, extravasation, and homing. Epithelial-mesenchymal transition (EMT), as well as hybrid E/M state, are biological processes, that involve both natural embryogenesis and tissue regeneration, and abnormal conditions including organ fibrosis or metastasis. In this context, some evidence reveals possible footprints of the important EMT-related pathways which may be affected in different EMFs treatments. In this article, critical EMT molecules and/or pathways which can be potentially affected by EMFs (e.g., VEGFR, ROS, P53, PI3K/AKT, MAPK, Cyclin B1, and NF-кB) are discussed to shed light on the mechanism of EMFs anti-cancer effect.

A novel computational predictive biological approach distinguishes Integrin β1 as a salient biomarker for breast cancer chemoresistance

Chemoresistance is a primary cause of breast cancer treatment failure, and protein-protein interactions significantly contribute to chemoresistance during different stages of breast cancer progression. In pursuit of novel biomarkers and relevant protein-protein interactions occurring during the emergence of breast cancer chemoresistance, we used a computational predictive biological (CPB) approach. CPB identified associations of adhesion molecules with proteins connected with different breast cancer proteins associated with chemoresistance. This approach identified an association of Integrin β1 (ITGB1) with chemoresistance and breast cancer stem cell markers. ITGB1 activated the Focal Adhesion Kinase (FAK) pathway promoting invasion, migration, and chemoresistance in breast cancer by upregulating Erk phosphorylation. FAK also activated Wnt/Sox2 signaling, which enhanced self-renewal in breast cancer. Activation of the FAK pathway by ITGB1 represents a novel mechanism linked to breast cancer chemoresistance, which may lead to novel therapies capable of blocking breast cancer progression by intervening in ITGB1-regulated signaling pathways.

MAPKs in the early steps of senescence implemEMTation

Evidence is accumulating that the earliest stages of the DNA damage response can direct cells toward senescence instead of other cell fates. In particular, tightly regulated signaling through Mitogen-Activated Protein Kinases (MAPKs) in early senescence can lead to a sustained pro-survival program and suppress a pro-apoptotic program. Importantly, an epithelial-to-mesenchymal Transition (EMT)-like program appears essential for preventing apoptosis and favoring senescence following DNA damage. In this review, we discuss how MAPKs might influence EMT features to promote a senescent phenotype that increases cell survival at the detriment of tissue function.

Traditional Chinese Medicine has great potential as candidate drugs for lung cancer: A review

ETHNOPHARMACOLOGICAL RELEVANCE

With high mortality and morbidity rates, lung cancer (LC) has become one of the major threats to human health. The treatment strategies for LC currently face issues, such as drug resistance and body tolerance. Traditional Chinese medicine (TCM) is characterized by novel pharmacological mechanisms, low toxicity, and limited side effects. TCM includes a substantial number of biologically active ingredients, several of which are effective monomeric agents against LC. An increasing number of researchers are focusing their efforts on the discovery of active anti-cancer ingredients in TCM.

AIM OF THE REVIEW

In this review, we summarized the anti-LC mechanisms of five types of TCM monomeric compounds. Our goal is to provide research ideas for the identification of new prospective medication candidates for the treatment of LC.

MATERIALS AND METHODS

We collected reports on the anti-LC effects of TCM monomers from web databases, including PubMed, Science Direct, Web of Science, and Europe PubMed Central. Among the keywords used were "lung cancer," "traditional Chinese medicine," "pharmacology," and their combinations thereof. Then, we systematically summarized the anti-LC efficacy and related mechanisms of TCM monomers.

RESULTS

Based on the available literature, this paper reviewed the therapeutic effects and mechanisms of five types of TCM monomers on LC. The characteristics of TCM monomers include the capabilities to suppress the tumor cell cycle, inhibit proliferation, induce apoptosis, promote autophagy, inhibit tumor cell invasion and metastasis, and enhance efficacy or reduce drug resistance when combined with cytotoxic agents and other methods to arrest the progression of LC and prolong the survival of patients.

CONCLUSIONS

TCM contains numerous flavonoids, alkaloids, terpenoids, polyphenols, and other active compounds that are effective against LC. Given their chemical structure and pharmacological properties, these monomers are suitable as candidate drugs for the treatment of LC.

Construction of crizotinib resistant models with CD74-ROS1 D2033N and CD74-ROS1 S1986F point mutations to explore resistance mechanism and treatment strategy

Targeted therapy is an essential treatment for non-small cell lung cancer (NSCLC) that is always associated with the drug resistance. c-ros oncogene 1 (ROS1) gene point mutation is one of the leading factors causing drug resistance. However, the point mutation cell models of crizotinib are challenging to obtain, causing few reports on the drug resistance mechanism and the treatment strategy. We constructed CD74-ROS1 D2033N and CD74-ROS1 S1986F point mutant plasmids by fusion PCR technology and transfected them into A549 cells. Western blot and MTT assay proved that the drug-resistant cell lines were successfully transfected. The transwell assay confirmed that the mutant cells' motor abilities were significantly increased compared with the wild-type group. In addition, focal adhesion kinase (FAK) was significantly increased in mutant cells. Moreover, crizotinib resistance occurred in the mutant cells through the activation of FAK / phosphatidylinositol 3-kinase (PI3K) / protein kinase B (AKT) pathway. Next, crizotinib was combined with defactinib, a FAK inhibitor, to further explore its therapeutic effect. The results showed that the combination could significantly inhibit the proliferation, invasion and migration of mutant cells. In conclusion, we proved that CD74-ROS1 D2033N and CD74-ROS1 S1986F point mutant NSCLC cells were resistant to crizotinib through the activation of FAK/PI3K/AKT signaling pathway, and inhibiting FAK/PI3K/AKT signaling pathway activation by defactinib could overcome drug resistance in mutant cells.

A reciprocal feedback between colon cancer cells and Schwann cells promotes the proliferation and metastasis of colon cancer

BACKGROUND

Research has indicated that the emergence of Schwann cells around premalignant lesions of colon cancer might be an early indicator promoting the onset of tumorigenesis. The present study explored the communication between colon cancer cells and Schwann cells.

METHODS

Immunofluorescence analyses were conducted to examine the differential distribution of Schwann cells within colon cancer tissues and normal colon tissues. CCK8 assay, colony formation assay, wound healing assay, and transwell assay were performed to investigate the interaction between colon cancer cells and Schwann cells. Exosomes derived from colon cancer cells were isolated to further explore the effect of colon cancer cells on Schwann cells. Gain- and loss-of function experiments, luciferase reporter assays, chromatin immunoprecipitation assays, and immunohistochemistry assays were performed to reveal the cross-talk between colon cancer cells and Schwann cells. Furthermore, colon cancer cells co-cultured with Schwann cells were transplanted into nude mice for evaluating their effect on tumor proliferation and metastasis in vivo.

RESULTS

The clinicopathological characteristics indicated that Schwann cells were enriched in colon cancer tissues and were associated with tumor metastasis and poor prognosis. The co-culture of Schwann cells with colon cancer cells promoted the proliferation and migration of colon cancer cells and Schwann cells, which was mediated by nerve growth factor (NGF) secreted from Schwann cells. Exosomal miR-21-5p released by colon cancer cells inhibited VHL expression in Schwann cells, which in turn stabilized the HIF-1α protein and increased the transcription of NGF. Meanwhile, the Schwann cells-derived NGF activated TrkA/ERK/ELK1/ZEB1 signaling pathway in colon cancer cells, which further enhanced the expression of exosomal miR-21-5p. Inhibition of either NGF or miR-21-5p significantly inhibited the proliferation and metastasis of transplanted colon cancer cells in nude mice. Coincidently, miR-21-5p was positively associated with the expression of NGF, p-ERK, p-ELK1, and ZEB1 in human colon cancer tissues.

CONCLUSIONS

Our results implicated a reciprocal communication between colon cancer cells and Schwan cells that promoted the proliferation and metastasis of colon cancer, and identified NGF and exosomal miR-21-5p as potential therapeutic targets for the treatment of colon cancer.

miR-145-5p Targets Sp1 in Non-Small Cell Lung Cancer Cells and Links to BMI1 Induced Pemetrexed Resistance and Epithelial-Mesenchymal Transition

Pemetrexed is a folic acid inhibitor used as a second-line chemotherapeutic agent for the treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC), which accounts for 85% of lung cancers. However, prolonged treatment with pemetrexed may cause cancer cells to develop resistance. In this study, we found increased expressions of BMI1 (B Lymphoma Mo-MLV insertion region 1 homolog) and Sp1 and a decreased expression of miR-145-5p was found in pemetrexed-resistant A400 cells than in A549 cells. Direct Sp1 targeting activity of miR-145-5p was demonstrated by a luciferase based Sp1 3'-UTR reporter. Changed expression of miR-145-5p in A400 or A549 cells by transfection of miR-145-5p mimic or inhibitor affected the sensitivity of the cells to pemetrexed. On the other hand, the overexpression of Sp1 in A549 cells caused the decreased sensitivity to pemetrexed, induced cell migratory capability, and epithelial-mesenchymal transition (EMT) related transcription factors such as Snail Family Transcriptional Repressor 1 and Zinc Finger E-Box Binding Homeobox 1. In addition, the overexpression of BMI1 in the A549 cells resulted in an increase in Sp1 and a decrease in miR-145-5p accompanied by the elevations of cell proliferation and EMT transcription factors, which could be reduced by the overexpression of miR-145-5p or by treatment with the Sp1 inhibitor of mithramycin A. In conclusion, the results of this study suggest that the downregulation of miR-145-5p by BMI1 overexpression could lead to the enhanced expression of Sp1 to induce the EMT process in pemetrexed-resistant NSCLC cells. These results suggest that increasing miR-145-5p expression by delivering RNA drugs may serve as a sensitizing agent for pemetrexed-resistant NSCLC patients.

The role of the ZEB1–neuroinflammation axis in CNS disorders

Zinc finger E-box binding homeobox 1 (ZEB1) is a master modulator of the epithelial–mesenchymal transition (EMT), a process whereby epithelial cells undergo a series of molecular changes and express certain characteristics of mesenchymal cells. ZEB1, in association with other EMT transcription factors, promotes neuroinflammation through changes in the production of inflammatory mediators, the morphology and function of immune cells, and multiple signaling pathways that mediate the inflammatory response. The ZEB1–neuroinflammation axis plays a pivotal role in the pathogenesis of different CNS disorders, such as brain tumors, multiple sclerosis, cerebrovascular diseases, and neuropathic pain, by promoting tumor cell proliferation and invasiveness, formation of the hostile inflammatory micromilieu surrounding neuronal tissues, dysfunction of microglia and astrocytes, impairment of angiogenesis, and dysfunction of the blood–brain barrier. Future studies are needed to elucidate whether the ZEB1–neuroinflammation axis could serve as a diagnostic, prognostic, and/or therapeutic target for CNS disorders.

ERK inactivation enhances stemness of NSCLC cells via promoting Slug-mediated epithelial-to-mesenchymal transition

Rationale: The mitogen-activated protein kinase pathway (MAPK) is one of the major cancer-driving pathways found in non-small cell lung cancer (NSCLC) patients. ERK inhibitors (ERKi) have been shown to be effective in NSCLC patients with MAPK pathway mutations. However, like other MAPK inhibitors, ERKi rarely confers complete and durable responses. The mechanism of tumor relapse after ERKi treatment is yet defined. Methods: To best study the mechanism of tumor relapse after ERK inhibitor treatment in NSCLC patients, we treated various NSCLC cell lines and patient-derived xenograft (PDX) with ERK inhibitors and evaluated the enrichment of cancer stem cell (CSC) population. We then performed a Next-generation sequencing (NGS) to identify potential pathways that are responsible for the CSC enrichment. Further, the involvement of specific pathways was examined using molecular and cellular methods. Finally, we investigated the therapeutic benefits of ERKi treatment combined with JAK/STAT pathway inhibitor using cellular and xenograft NSCLC models. Results: We found that ERKi treatment expands the CSC population in NSCLC cells through enhanced epithelial-to-mesenchymal transition (EMT)-mediated cancer cell dedifferentiation. Mechanistically, ERK inactivation induces EMT via pSTAT3-mediated upregulation of Slug, in which, upregulation of miR-204 and downregulation of SPDEF, a transcription repressor of Slug, are involved. Finally, the JAK/STAT pathway inhibitor Ruxolitinib blocks the ERK inactivation-induced EMT and CSC expansion, as well as the tumor progression in xenograft models after ERKi treatment. Conclusions: This study revealed a potential tumor relapse mechanism of NSCLC after ERK inhibition through the unintended activation of the EMT program, ascertained the pSTAT-miR-204-SPDEF-Slug axis, and provided a promising combination inhibitor approach to prevent tumor relapse in patients.

Particulate matter 2.5 exposure induces epithelial-mesenchymal transition via PI3K/AKT/mTOR pathway in human retinal pigment epithelial ARPE-19 cells

Exposure to particulate matter 2.5 (PM2.5) has been linked to ocular surface diseases, yet knowledge of the molecular mechanism impacted on retina pathogenesis is limited. Therefore, the purpose of this study was to explore the effects and involved factors of PM2.5 exposure in human retinal pigment epithelial APRE-19 cells. Our data revealed a decreased cell viability and an increased migratory ability in APRE-19 cells after PM2.5 stimulation. The MMP-2 and MMP-9 protein levels were markedly increased while the MMPs regulators TIMP-1 and TIMP-2 were significantly reduced in PM2.5-exposed APRE-19 cells. PM2.5 also increased pro-MMP-2 expression in the cell culture supernatants. Additionally, PM2.5 promoted the EMT markers through the activation of PI3K/AKT/mTOR pathway. Moreover, the ICAM-1 production was also remarkably increased by PM2.5 but reduced by PI3K/AKT inhibitor LY294002 in APRE-19 cells. Taken together, these results suggest that PM2.5 promotes EMT in a PI3K/AKT/mTOR-dependent manner in the retinal pigment epithelium.

Histone deacetylase 3 promotes alveolar epithelial-mesenchymal transition and fibroblast migration under hypoxic conditions

Epithelial–mesenchymal transition (EMT), a process by which epithelial cells undergo a phenotypic conversion that leads to myofibroblast formation, plays a crucial role in the progression of idiopathic pulmonary fibrosis (IPF). Recently, it was revealed that hypoxia promotes alveolar EMT and that histone deacetylases (HDACs) are abnormally overexpressed in the lung tissues of IPF patients. In this study, we showed that HDAC3 regulated alveolar EMT markers via the AKT pathway during hypoxia and that inhibition of HDAC3 expression by small interfering RNA (siRNA) decreased the migration ability and invasiveness of diseased human lung fibroblasts. Furthermore, we found that HDAC3 enhanced the migratory and invasive properties of fibroblasts by positively affecting the EMT process, which in turn was affected by the increased and decreased levels of microRNA (miR)-224 and Forkhead Box A1 (FOXA1), respectively. Lastly, we found this mechanism to be valid in an in vivo system; HDAC3 siRNA administration inhibited bleomycin-induced pulmonary fibrosis in mice. Thus, it is reasonable to suggest that HDAC3 may accelerate pulmonary fibrosis progression under hypoxic conditions by enhancing EMT in alveolar cells through the regulation of miR-224 and FOXA1. This entire process, we believe, offers a novel therapeutic approach for pulmonary fibrosis.

Inhibiting an enzyme that boosts the invasiveness of fibrosis-related cells could prove to be a novel therapeutic strategy for treating idiopathic lung fibrosis. Lung fibrosis progresses via the transition of epithelial cells into myofibroblasts, which are migratory invasive cell types that secrete collagen and deposit excessive extracellular material. Low oxygen conditions (hypoxia) accelerate this transition process. Scientists recently identified a group of histone deacetylases (HDACs) that are significantly overexpressed in the lung tissues of patients with fibrosis. In experiments on mice and human cell lines, Jeong-Woong Park and Se-Hee Kim at Gachon University Gil Medical Center, Incheon, South Korea, and co-workers demonstrated that under hypoxic conditions, HDAC3 increases the cellular transition to myofibroblasts by regulating the expression of a key microRNA and its target gene. Inhibiting HDAC3 suppresses the migration and invasiveness of lung myofibroblasts.

Epithelial–mesenchymal transition: The history, regulatory mechanism, and cancer therapeutic opportunities

Epithelial–mesenchymal transition (EMT) is a program wherein epithelial cells lose their junctions and polarity while acquiring mesenchymal properties and invasive ability. Originally defined as an embryogenesis event, EMT has been recognized as a crucial process in tumor progression. During EMT, cell–cell junctions and cell–matrix attachments are disrupted, and the cytoskeleton is remodeled to enhance mobility of cells. This transition of phenotype is largely driven by a group of key transcription factors, typically Snail, Twist, and ZEB, through epigenetic repression of epithelial markers, transcriptional activation of matrix metalloproteinases, and reorganization of cytoskeleton. Mechanistically, EMT is orchestrated by multiple pathways, especially those involved in embryogenesis such as TGFβ, Wnt, Hedgehog, and Hippo, suggesting EMT as an intrinsic link between embryonic development and cancer progression. In addition, redox signaling has also emerged as critical EMT modulator. EMT confers cancer cells with increased metastatic potential and drug resistant capacity, which accounts for tumor recurrence in most clinic cases. Thus, targeting EMT can be a therapeutic option providing a chance of cure for cancer patients. Here, we introduce a brief history of EMT and summarize recent advances in understanding EMT mechanisms, as well as highlighting the therapeutic opportunities by targeting EMT in cancer treatment.

Transcriptional and post-transcriptional control of epithelial-mesenchymal plasticity: why so many regulators?

The dynamic transition between epithelial-like and mesenchymal-like cell states has been a focus for extensive investigation for decades, reflective of the importance of Epithelial-Mesenchymal Transition (EMT) through development, in the adult, and the contributing role EMT has to pathologies including metastasis and fibrosis. Not surprisingly, regulation of the complex genetic networks that underlie EMT have been attributed to multiple transcription factors and microRNAs. What is surprising, however, are the sheer number of different regulators (hundreds of transcription factors and microRNAs) for which critical roles have been described. This review seeks not to collate these studies, but to provide a perspective on the fundamental question of whether it is really feasible that so many regulators play important roles and if so, what does this tell us about EMT and more generally, the genetic machinery that controls complex biological processes.

Chelerythrine inhibits the progression of glioblastoma by suppressing the TGFB1-ERK1/2/Smad2/3-Snail/ZEB1 signaling pathway

AIMS

Glioblastoma (GBM) is the most common and aggressive intracranial tumor with poor prognosis. A large majority of clinical chemotherapeutic agents cannot achieve the desired therapeutic effect. Chelerythrine (CHE), a natural component with multitudinous pharmacological functions, has been proven to have outstanding antitumor effects in addition to antibacterial, anti-inflammatory, and hypotensive effects. However, the anti-GBM effect of CHE has not been reported to date. The purpose of this paper is to observe the anti-GBM effect of CHE and further explore the related mechanism.

MATERIALS AND METHODS

GBM cell lines (U251 and T98G) and BALB/c nude mice were used in the experiments. Methyl thiazolyl tetrazolium (MTT) and clone formation assays were applied to detect the viability, proliferation and stemness of GBM cells. Flow cytometry was utilized to identify the effect of CHE on GBM apoptosis. Scratch and Transwell experiments reflected the migration and invasion of cells. In vivo, xenograft tumors were implanted subcutaneously in nude mice. The progression of tumors was assessed by ultrasound and magnetic resonance imaging. Finally, western blot, bioinformatics, and immunohistochemistry experiments were used to explore the molecular mechanisms in depth.

KEY FINDINGS

In vitro tests showed that CHE inhibited the proliferation, stemness, migration, and invasion of GBM cells and induced apoptosis. In vitro, CHE was observed to restrain the progression of xenograft tumors. We eventually proved that the cytotoxicity of CHE was relevant to the TGFB1-ERK1/2/Smad2/3-Snail/ZEB1 signaling pathway.

SIGNIFICANCE

CHE inhibited GBM progression by inhibiting the TGFB1-ERK1/2/Smad2/3-Snail/ZEB1 signaling pathway and is a potential chemotherapeutic drug for GBM.

Slug and Vimentin downregulation at the metastatic site is associated with Skip-N2 metastasis of lung adenocarcinoma

OBJECTIVE

Lung cancer displays heterogeneity both in the tumor itself and in its metastatic regions. One interesting behavior of the tumor is known as Skip N2 metastasis, which N2 lymph nodes contain tumor cells while N1 are clean. In this study, mRNA levels of epithelial mesenchymal transition (EMT) related genes in skip N2 and normal N2 involvements of non-small cell lung cancer tissues were investigated to evaluate the possible molecular background that may contribute to the pathogenesis of Skip N2 metastasis.

MATERIALS AND METHODS

Eighty-three surgically resected and paraffin embedded lymph node samples of lung cancer patients were analyzed in this study, which 40 of them were Skip N2. N2 tissues were sampled from 50% tumor containing areas and total RNA was extracted. mRNA levels for 18S, E-cadherin, Vimentin, ZEB1 and SLUG were analyzed via qPCR and E-cadherin and vimentin protein levels via immunohistochemistry (IHC). Bioinformatic analysis were adopted using online datasets to evaluate significantly co-expressed genes with SLUG in lung cancer tissue samples.

RESULTS

Skip-N2 patients who had adenocarcinoma subtype had better survival rates. Comparative analysis of PCR results indicated that Skip N2 tumor tissues had increased E-Cadherin/Vimentin ratio and ZEB1 mRNA expression, and significantly decreased levels of SLUG. E-cadherin IHC staining were higher in Skip N2 and Vimentin were in Non-Skip N2. TP63 had a strong correlation with SLUG expression in the bioinformatics analyses.

CONCLUSION

The results indicate that, at molecular level, Skip N2 pathogenesis has different molecular background and regulation of SLUG expression may orchestrate the process.

Potential underlying genetic associations between keratoconus and diabetes mellitus

Background Keratoconus (KC) is the most common ectatic corneal disease, characterized by significantly localized thinning of the corneal stroma. Genetic, environmental, hormonal, and metabolic factors contribute to the pathogenesis of KC. Additionally, multiple comorbidities, such as diabetes mellitus, may affect the risk of KC. Main Body Patients with diabetes mellitus (DM) have been reported to have lower risk of developing KC by way of increased endogenous collagen crosslinking in response to chronic hyperglycemia. However, this remains a debated topic as other studies have suggested either a positive association or no association between DM and KC. To gain further insight into the underlying genetic components of these two diseases, we reviewed candidate genes associated with KC and central corneal thickness in the literature. We then explored how these genes may be regulated similarly or differentially under hyperglycemic conditions and the role they play in the systemic complications associated with DM. Conclusion Our comprehensive review of potential genetic factors underlying KC and DM provides a direction for future studies to further determine the genetic etiology of KC and how it is influenced by systemic diseases such as diabetes.

L-Type Amino Acid Transporter 1 Regulates Cancer Stemness and the Expression of Programmed Cell Death 1 Ligand 1 in Lung Cancer Cells

The l-type amino acid transporter 1 (LAT1) is a membranous transporter that transports neutral amino acids for cells and is dysregulated in various types of cancer. Here, we first observed increased LAT1 expression in pemetrexed-resistant non-small cell lung cancer (NSCLC) cells with high cancer stem cell (CSC) activity, and its mRNA expression level was associated with shorter overall survival in the lung adenocarcinoma dataset of the Cancer Genome Atlas database. The inhibition of LAT1 by a small molecule inhibitor, JPH203, or by RNA interference led to a significant reduction in tumorsphere formation and the downregulation of several cancer stemness genes in NSCLC cells through decreased AKT serine/threonine kinase (AKT)/mammalian target of rapamycin (mTOR) activation. The treatment of the cell-permeable leucine derivative promoted AKT/mTOR phosphorylation and reversed the inhibitory effect of JPH203 in the reduction of CSC activity in pemetrexed-resistant lung cancer cells. Furthermore, we observed that LAT1 silencing caused the downregulation of programmed cell death 1 ligand 1 (PD-L1) on lung cancer cells. The PD-L1⁺/LAT1⁺ subpopulation of NSCLC cells displayed great CSC activity with increased expression of several cancer stemness genes. These data suggest that LAT1 inhibitors can serve as anti-CSC agents and could be used in combination with immune checkpoint inhibitors in lung cancer therapy.

DCLK1-Short Splice Variant Promotes Esophageal Squamous Cell Carcinoma Progression via the MAPK/ERK/MMP2 Pathway

Cancer stem cell (CSC) marker doublecortin-like kinase 1 (DCLK1) contributes greatly to the malignancy of gastrointestinal cancers, and DCLK1-targeted agents have potential therapeutic value. However, the molecular pathways regulated by DCLK1-S (DCLK1 isoform 4), a shortened splice variant of DCLK1, still remain obscure. Here we found that the expression of DCLK1-S is significantly increased in human esophageal squamous cell carcinoma (ESCC) tissues and associated with malignant progression and poor prognosis. Functional studies indicated that silencing total of DCLK1 mediated by CRISPR/Cas9 inhibited ESCC cell proliferation, migration, and invasion. Conversely, these changes were largely reversed after DCLK1-S rescue or overexpression. More importantly, DCLK1-S significantly enhanced primary tumor formation and metastatic lung colonization in vivo. The Cancer Genome Atlas database and molecular analysis showed that DCLK1-S was closely related to the epithelial-mesenchymal transition (EMT) process in patients with ESCC. Further RNA sequencing and Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that MAPK signaling pathway was significantly enriched. Our in vitro study proclaimed that DCLK1-S induced MMP2 expression in ESCC cells via MAPK/ERK signaling, leading to the activation of EMT. In addition, administration of ERK1/2 blocker SCH772984 attenuated the proliferative and migratory phenotype induced by DCLK1-S. In conclusion, these findings suggest that DCLK1-S may be a key molecule in MAPK/ERK/MMP2 pathway-mediated progression of ESCC, and that it has potential as a biomarker or therapeutic target to improve outcomes in patients with ESCC. IMPLICATIONS: : DCLK1-S induces ESCC progression by activating the MAPK/ERK/MMP2 axis and may serve as a prognostic biomarker or therapeutic target for patients with ESCC.

Harmine-inspired design and synthesis of benzo[d]imidazo[2,1-b]thiazole derivatives bearing 1,3,4-oxadiazole moiety as potential tumor suppressors

Standard chemotherapy and personalized target therapies are commonly used in patients with advanced non-small cell lung cancer (NSCLC). However, multidrug resistance (MDR) and tumor metastasis lead to the decline of therapeutic efficacy, which are closely related to epithelial-mesenchymal transition (EMT). Twist1, an EMT transcription factor, plays an essential role in promoting EMT, MDR and tumor metastasis. In view of the essential role of Twist1 in the tumorigenesis of NSCLC, developing antitumor small molecules that can suppress the expression of Twist1 is of far-reaching significance for the treatment of NSCLC. A series of novel benzo[d]imidazo[2,1-b]thiazole derivatives possessing 1,3,4-oxadiazole moiety were designed based on the structure of the first-in-class Twist1 inhibitor harmine. Among the synthetic twenty-two compounds, the compound containing 2-(piperidine-1-yl) ethyl exhibited remarkable anti-proliferative activity with IC₅₀ value of 2.03 μM and 9.80 μM against A549 and H2228 cell lines superior to harmine (IC₅₀ = 17.12 μM against A549, IC₅₀ = 31.06 μM against H2228). Meanwhile, western blot assay showed that the optimal compound significantly down-regulated Twist1 protein expression in a dose-dependent manner and reduced Twist1 level better than harmine. Collectively, the promising compound was identified a potential antineoplastic lead with the ability of down-regulating Twist1 level.

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.

Xanthohumol Impairs the PMA-Driven Invasive Behaviour of Lung Cancer Cell Line A549 and Exerts Anti-EMT Action

Xanthohumol (XN), the main prenylated flavonoid from hop cones, has been recently reported to exert significant proapoptotic, anti-proliferative, and growth inhibitory effects against lung cancer in both in vitro and in vivo studies. However, its anti-metastatic potential towards this malignancy is still unrevealed. Previously, we indicated that the human lung adenocarcinoma A549 cell line was sensitive to XN treatment. Therefore, using the same tumour cell model, we have studied the influence of XN on the phorbol-12-myristate-13-acetate (PMA)-induced cell migration and invasion. The effects of XN on the expression/activity of pro-invasive MMP-9 and MMP-2 and the expression of MMP inhibitors, i.e., TIMP-1 and TIMP-2 (anti-angiogenic factors), were evaluated. Additionally, the influence of XN on the production of the key pro-angiogenic cytokine, i.e., VEGF, and the release of TGF-β, which is both a pro-angiogenic cytokine and an epithelial-mesenchymal transition (EMT) stimulator, was studied. Furthermore, the influence of XN on the expression of EMT-associated proteins such as E-cadherin and α-E-catenin (epithelial markers), vimentin and N-cadherin (mesenchymal markers), and Snail-1 (transcriptional repressor of E-cadherin) was studied. To elucidate the molecular mechanism underpinning the XN-mediated inhibition of metastatic progression in PMA-activated cells, the phosphorylation levels of AKT, FAK, and ERK1/2 kinases, which are signalling molecules involved in EMT program activation, were assayed. The results showed that XN in non-cytotoxic concentrations impaired the PMA-driven migratory and invasive capacity of A549 cells by decreasing the level of expression of MMP-9 and concomitantly increasing the expression of the TIMP-1 protein, i.e., a specific blocker of pro-MMP-9 activation. Moreover, XN decreased the PMA-induced production of VEGF and TGF-β. Furthermore, the XN-treatment counteracted the PMA-induced EMT of the A549 cells by the upregulation of E-cadherin and α-E-catenin and the downregulation of N-cadherin, vimentin, and Snail-1 expression. The proposed mechanism underlying the anti-invasive XN activity involved the inhibition of the ERK/MAPK pathway and suppression of FAK and PI3/AKT signalling. Our results suggesting migrastatic properties of XN against lung cancer cells require further verification in in vivo assays.

The Effect of Suppression Taurine on Relocation and Epithelial-Mesenchymal Transition in Mankind Lung Cancer Cells

Aim

Taurine is believed to have antioxidant properties and has been implicated in the treatment of neurodegenerative disease, atherosclerosis, coronary heart disease, and prostate cancer. This research focused on taurine inhibition effects of expression related to migration and epithelial-mesenchymal transition- (EMT-) A549 study on related genes of human being non-small-cell lung cancer.

Methods

MTT assays assessed cell viability and a RadiusTM assay showed that taurine also inhibited the lung cancer cell migration. Using RT-PCR and Western blot, the migration and EMT markers were identified and evaluated.

Results

We found that taurine significantly decreased the expression of migration markers matrix metallopeptidase 9 (MMP-9) and vascular endothelial growth factor (VEGF). In contrast, TIMP metallopeptidase inhibitor 1 (TIMP-1) and TIMP metallopeptidase inhibitor 2 (TIMP-2) expressions were increased with taurine treatment. In addition, we found an association between taurine treatment and the expression of EMT markers. The expression of epithelial marker E-cadherin and the mesenchymal marker N-cadherin TWIST-1 was decreased, but the expression of zinc finger protein SNAIL-1 and E-zinc finger homeobox 1 (ZEB-1) was increased.

Conclusion

Taken together, our study strongly suggests the therapeutic significance of taurine, which possesses antimigration activity and induces EMT markers expression in lung cancer cells.

Antiaging gene Klotho regulates epithelial-mesenchymal transition and increases sensitivity to pemetrexed by inducing lipocalin-2 expression

Epithelial-mesenchymal transition (EMT) is considered to serve an important role in the metastatic/invasive ability of cancer cells, in the acquisition of drug resistance, and in metabolic reprogramming. In the present study, it was hypothesized that the Klotho gene is involved in the metastatic/invasive ability of lung cancer. We previously reported an association between Klotho expression and overall survival in patients with small cell lung cancer and large cell neuroendocrine cancer. We also found that Klotho expression was associated with EMT-related molecules in lung squamous cell carcinoma. The present study aimed to analyze the function of the Klotho gene and to elucidate its relevance to the regulation of the EMT. For this purpose, GFP-Klotho plasmids were transfected into lung adenocarcinoma cells (A549) and cell lines with stable expression (A549/KL-1 and A549/KL-2) were established. A549/KL-1 cells expressed higher levels of Klotho protein by western blot analysis compared with A549/KL-2 cells. In western blotting of A549 and A549/KL-1 cells, the expression of the mesenchymal marker N-cadherin was found to be completely inhibited in A549/KL-1 cells suggesting that Klotho expression may regulate the EMT in cancer cells via the inhibition of N-cadherin. The results of the sensitivity tests demonstrated that A549/KL-1 cells were significantly more sensitive to pemetrexed compared with A549 cells (IC₅₀ A549/KL-1 vs. A549 cells, 0.1 µM vs. 0.7 µM). The results of the microarray analysis demonstrated that a very high level of lipocalin-2 (LCN2) expression was induced in the A549/KL-1 cells. Klotho overexpression completely suppressed the expression of mesenchymal markers, such as N-cadherin and Snail1 (Snail). The results of the present study suggested that there may be a new mechanism of action for the antitumor effects of pemetrexed, namely, LCN2-mediated modulation of N-cadherin expression. Klotho expression during cancer treatment has great potential as a predictor for efficacy of pemetrexed and as a factor in the selection of personalized medicine for postoperative adjuvant chemotherapy.

Nerve growth factor receptor increases the tumor growth and metastatic potential of triple-negative breast cancer cells

Cellular heterogeneity and the lack of metastatic biomarkers limit the diagnosis of and development of therapies for metastatic triple-negative breast cancer (TNBC). Thus, development of new clinically relevant markers is urgently needed. By using RNA-seq analysis, we found that nerve growth factor receptor (NGFR) was highly expressed in metastatic lung clones of MDA-MB-231 cells. This high level of NGFR expression was necessary for TNBC cells to grow into tumor spheres under nonadhesive conditions, resist anoikis, promote primary tumor growth and increase metastasis in mice. NGFR was also expressed at a high level in a greater number of TNBC patients (45%) than non-TNBC patients (23%), enriched in higher grade tumors, and negatively correlated with the overall survival of TNBC patients. Mechanistic analysis indicated that NGFR exerted its prometastatic effects by binding with neurotrophic receptor tyrosine kinase 3 (TrkC) mainly through a ligand-independent manner, which activated the MEK-ERK1-ZEB1 and PI3K-AKT signaling pathways, increased the level of fibronectin, and decreased the expression of PUMA. Notably, we observed that NGFR expression in TrkC-positive metastatic clones reduced cellular sensitivity to anti-Trk therapy. Moreover, WNT family member 5a (WNT5A) and TrkC activated NGFR transcription in a ZEB1-dependent manner. Taken together, this study identified NGFR as a novel driver for transforming TNBC into higher grade metastatic tumors. Our findings provide the basis for the future development of NGFR as a diagnostic and prognostic marker for determining the metastatic potential of TNBC and as a therapeutic target for treating TNBC patients.

Mechanisms of resistance to chemotherapy in non-small cell lung cancer

Non-small cell lung cancer (NSCLC), which represents 80-85% of lung cancer cases, is one of the leading causes of human death worldwide. The majority of patients undergo an intensive and invasive treatment regimen, which may include radiotherapy, chemotherapy, targeted therapy, immunotherapy, or a combination of these, depending on disease stage and performance status. Despite advances in therapeutic regimens, the 5-year survival of NSCLC is approximately 20-30%, largely due to diagnosis at advanced stages. Conventional chemotherapy is still the standard treatment option for patients with NSCLC, especially those with advanced disease. However, the emergence of resistance to chemotherapeutic agents (chemoresistance) poses a significant obstacle to the management of patients with NSCLC. Therefore, to develop efficacious chemotherapeutic approaches for NSCLC, it is necessary to understand the mechanisms underlying chemoresistance. Several mechanisms are known to mediate chemoresistance. These include altered cellular targets for chemotherapy, decreased cellular drug concentrations, blockade of chemotherapy-induced cell cycle arrest and apoptosis, acquisition of epithelial-mesenchymal transition and cancer stem cell-like phenotypes, deregulated expression of microRNAs, epigenetic modulation, and the interaction with tumor microenvironments. In this review, we summarize the mechanisms underlying chemoresistance and tumor recurrence in NSCLC and discuss potential strategies to avoid or overcome chemoresistance.

Transient Receptor Potential Channel 6 Knockout Ameliorates Kidney Fibrosis by Inhibition of Epithelial-Mesenchymal Transition

Kidney fibrosis is generally confirmed to have a significant role in chronic kidney disease, resulting in end-stage kidney failure. Epithelial–mesenchymal transition (EMT) is an important molecular mechanism contributing to fibrosis. Tubular epithelial cells (TEC), the major component of kidney parenchyma, are vulnerable to different types of injuries and are a significant source of myofibroblast by EMT. Furthermore, TRPC6 knockout plays an anti-fibrotic role in ameliorating kidney damage. However, the relationship between TRPC6 and EMT is unknown. In this study, TRPC6^−/− and wild-type (WT) mice were subjected to a unilateral ureteric obstruction (UUO) operation. Primary TEC were treated with TGF-β1. Western blot and immunofluorescence data showed that fibrotic injuries alleviated with the inhibition of EMT in TRPC6^−/− mice compared to WT mice. The activation of AKT-mTOR and ERK1/2 pathways was down-regulated in the TRPC6^−/− mice, while the loss of Na⁺/K⁺-ATPase and APQ1 was partially recovered. We conclude that TRPC6 knockout may ameliorate kidney fibrosis by inhibition of EMT through down-regulating the AKT-mTOR and ERK1/2 pathways. This could contribute to the development of effective therapeutic strategies on chronic kidney diseases.

Cyano Enone-Bearing Triterpenoid Soloxolone Methyl Inhibits Epithelial-Mesenchymal Transition of Human Lung Adenocarcinoma Cells In Vitro and Metastasis of Murine Melanoma In Vivo

Introduction of α-cyano α,β-unsaturated carbonyl moiety into natural cyclic compounds markedly improves their bioactivities, including inhibitory potential against tumor growth and metastasis. Previously, we showed that cyano enone-bearing derivatives of 18βH-glycyrrhetinic (GA) and deoxycholic acids displayed marked cytotoxicity in different tumor cell lines. Moreover, GA derivative soloxolone methyl (SM) was found to induce ER stress and apoptosis in tumor cells in vitro and inhibit growth of carcinoma Krebs-2 in vivo. In this work, we studied the effects of these compounds used in non-toxic dosage on the processes associated with metastatic potential of tumor cells. Performed screening revealed SM as a hit compound, which inhibits motility of murine melanoma B16 and human lung adenocarcinoma A549 cells and significantly suppresses colony formation of A549 cells. Further study showed that SM effectively blocked transforming growth factor β (TGF-β)-induced epithelial-mesenchymal transition (EMT) of A549 cells: namely, inhibited TGF-β-stimulated motility and invasion of tumor cells as well as loss of their epithelial characteristics, such as, an acquisition of spindle-like phenotype, up- and down-regulation of mesenchymal (vimentin, fibronectin) and epithelial (E-cadherin, zona occludens-1 (ZO-1)) markers, respectively. Network pharmacology analysis with subsequent verification by molecular modeling revealed that matrix metalloproteinases MMP-2/-9 and c-Jun N-terminal protein kinase 1 (JNK1) can be considered as hypothetical primary targets of SM, mediating its marked anti-EMT activity. The inhibitory effect of SM on EMT revealed in vitro was further confirmed in a metastatic model of murine B16 melanoma: SM was found to effectively block metastatic dissemination of melanoma B16 cells in vivo, increase expression of E-cadherin and suppress expression of MMP-9 in lung metastatic foci. Altogether, our data provided valuable information for a better understanding of the antitumor activity of cyano enone-bearing semisynthetic compounds and revealed SM as a promising anti-metastatic drug candidate.

Is the Proteome of Bronchoalveolar Lavage Extracellular Vesicles a Marker of Advanced Lung Cancer?

Simple Summary

Bronchoalveolar lavage is routinely collected during bronchoscopy for cytology analysis in the diagnostic of lung cancer. Due to low sensitivity of this method, early-stage cancers are undetected, lowering the treatment success. In this study, we analyzed extracellular vesicles isolated from bronchoalveolar lavage of lung cancer suspects by mass spectrometry-based proteomics. The protein composition of bronchoalveolar lavage extracellular vesicles of late-stage cancer showed a higher proteome complexity associated with mortality within the two year follow-up period. We identified a potential therapeutic target DNMT3B complex which was significantly expressed in bronchoalveolar lavage extracellular vesicles as well as in tumor tissue. Bronchoalveolar lavage extracellular vesicles proteome analysis of immune markers indicates the presence of markers of innate immune and fibroblast cells.

Abstract

Acellular bronchoalveolar lavage (BAL) proteomics can partially separate lung cancer from non-lung cancer patients based on principal component analysis and multivariate analysis. Furthermore, the variance in the proteomics data sets is correlated mainly with lung cancer status and, to a lesser extent, smoking status and gender. Despite these advances BAL small and large extracellular vehicles (EVs) proteomes reveal aberrant protein expression in paracrine signaling mechanisms in cancer initiation and progression. We consequently present a case-control study of 24 bronchoalveolar lavage extracellular vesicle samples which were analyzed by state-of-the-art liquid chromatography-mass spectrometry (LC-MS). We obtained evidence that BAL EVs proteome complexity correlated with lung cancer stage 4 and mortality within two years´ follow-up (p value = 0.006). The potential therapeutic target DNMT3B complex is significantly up-regulated in tumor tissue and BAL EVs. The computational analysis of the immune and fibroblast cell markers in EVs suggests that patients who deceased within the follow-up period display higher marker expression indicative of innate immune and fibroblast cells (four out of five cases). This study provides insights into the proteome content of BAL EVs and their correlation to clinical outcomes.

Mechanisms of docetaxel resistance in prostate cancer: The key role played by miRNAs

One of the main problems with the treatment of metastatic prostate cancer is that, despite an initial positive response, the majority of patients develop resistance and progress. In particular, the resistance to docetaxel, the gold standard therapy for metastatic prostate cancer since 2010, represents one of the main factors responsible for the failure of prostate cancer therapy. According to the present knowledge, different processes contribute to the appearance of docetaxel resistance and non-coding RNA seems to play a relevant role in them. In this review, a comprehensive overview of the miRNA network involved in docetaxel resistance is described, highlighting the pathway/s affected by their activity.

Thymidylate synthase drives the phenotypes of epithelial-to-mesenchymal transition in non-small cell lung cancer

Background

Epithelial-to-mesenchymal transition (EMT) enhances motility, stemness, chemoresistance and metastasis. Little is known about how various pathways coordinate to elicit EMT’s different functional aspects in non-small cell lung cancer (NSCLC). Thymidylate synthase (TS) has been previously correlated with EMT transcription factor ZEB1 in NSCLC and imparts resistance against anti-folate chemotherapy. In this study, we establish a functional correlation between TS, EMT, chemotherapy and metastasis and propose a network for TS mediated EMT.

Methods

Published datasets were analysed to evaluate the significance of TS in NSCLC fitness and prognosis. Promoter reporter assay was used to sort NSCLC cell lines in TS^HIGH and TS^LOW. Metastasis was assayed in a syngeneic mouse model.

Results

TS levels were prognostic and predicted chemotherapy response. Cell lines with higher TS promoter activity were more mesenchymal-like. RNA-seq identified EMT as one of the most differentially regulated pathways in connection to TS expression. EMT transcription factors HOXC6 and HMGA2 were identified as upstream regulator of TS, and AXL, SPARC and FOSL1 as downstream effectors. TS knock-down reduced the metastatic colonisation in vivo.

Conclusion

These results establish TS as a theranostic NSCLC marker integrating survival, chemo-resistance and EMT, and identifies a regulatory network that could be targeted in EMT-driven NSCLC.

Steroid receptor RNA activator inhibits the migration, invasion and stemness characteristics of renal cell carcinoma cells

Renal cell carcinoma (RCC) has a high mortality rate among urological malignancies, and its underlying mechanisms remain unclear. Steroid receptor RNA coactivator (SRA) belongs to the long non-coding RNAs (lncRNAs) and has been demonstrated to be closely related to various types of cancer. In the present study, the decreased expression level of SRA was first confirmed in RCC tissues and cell lines by RT-qPCR. Using knockdown or overexpression systems, it was then found that SRA inhibited the proliferation of RCC cell lines and promoted their apoptosis. In addition, SRA suppressed the migration and invasion, and altered EMT-related markers in RCC cells. More importantly, it was demonstrated that SRA reduced percentage of CD44⁺/CD24⁻ cells and the sphere-forming efficiency. SRA also attenuated the expression levels of CD44, SOX-2, ABCG2 and OCT-4, which are all associated with cancer cell stemness characteristics. Although SRA increased the phosphorylation of extracellular-regulated protein kinase (ERK), the ERK1/2 pathway could not further interfere with the alteration of EMT-related markers mediated by SRA. Notably, the ERK inhibitor, PD98059, abolished ERK1/2 phosphorylation, whereas it did not exert any marked effects on cell proliferation and EMT-related markers mediated by SRA. Taken together, the findings of the present study indicate that SRA is an important molecule that inhibits the migration, invasion and stem cell characteristics of RCC cells; the ERK signaling pathway may not be involved in this process.

The AKT/GSK3-Mediated Slug Expression Contributes to Oxaliplatin Resistance in Colorectal Cancer via Upregulation of ERCC1

Although oxaliplatin serves as one of the first-line drugs prescribed for treating colorectal cancer (CRC), the therapeutic effect is disappointing due to drug resistance. So far, the molecular mechanisms mediating oxaliplatin resistance remain unclear. In this study, we found the chemoresistance in oxaliplatin-resistant HCT116 cells (HCT116/OXA) was mediated by the upregulation of ERCC1 expression. In addition, the acquisition of resistance induced epithelialmesenchymal transition (EMT) as well as the Slug overexpression. On the contrary, Slug silencing reversed the EMT phenotype, decreased ERCC1 expression, and ameliorated drug resistance. Further mechanistical studies revealed the enhanced Slug expression resulted from the activation of AKT/glycogen synthase kinase 3 (GSK3) signaling. Moreover, in CRC patients, coexpression of Slug and ERCC1 was observed, and increased Slug expression was significantly correlated with clinicopathological factors and prognosis. Taken together, the simultaneous inhibition of the AKT/GSK3/Slug axis may be of significance for surmounting metastasis and chemoresistance, thereby improving the therapeutic outcome of oxaliplatin.

BMI1-Mediated Pemetrexed Resistance in Non-Small Cell Lung Cancer Cells Is Associated with Increased SP1 Activation and Cancer Stemness

Lung cancer is the leading cause of cancer death worldwide and the therapeutic strategies include surgery, chemotherapy and radiation therapy. Non-small cell lung cancers (NSCLCs) account for around 85% of cases of lung cancers. Pemetrexed is an antifolate agent that is currently used as the second line chemotherapy drug in the treatment of advanced NSCLC patients with a response rate of 20–40%. The search for any combination therapy to improve the efficacy of pemetrexed is required. The existence of cancer stem cells (CSCs) is considered as the main reason for drug resistance of cancers. In this study, we first found that pemetrexed-resistant NSCLC cells derived from A549 cells displayed higher CSC activity in comparison to the parental cells. The expression of CSC related proteins, such as BMI1 or CD44, and the epithelial–mesenchymal transition (EMT) signature was elevated in pemetrexed-resistant NSCLC cells. We next discovered that the overexpression of BMI1 in A549 cells caused the pemetrexed resistance and inhibition of BMI1 by a small molecule inhibitor, PTC-209, or transducing of BMI1-specific shRNAs suppressed cell growth and the expression of thymidylate synthase (TS) in pemetrexed-resistant A549 cells. We further identified that BMI1 positively regulated SP1 expression and treatment of mithramycin A, a SP1 inhibitor, inhibited cell proliferation, as well as TS expression, of pemetrexed-resistant A549 cells. Furthermore, overexpression of BMI1 in A549 cells also caused the activation of EMT in and the enhancement of CSC activity. Finally, we demonstrated that pretreatment of PTC-209 in mice bearing pemetrexed-resistant A549 tumors sensitized them to pemetrexed treatment and the expression of Ki-67, BMI1, and SP1 expression in tumor tissues was observed to be reduced. In conclusion, BMI1 expression level mediates pemetrexed sensitivity of NSCLC cells and the inhibition of BMI1 will be an effective strategy in NSCLC patients when pemetrexed resistance has developed.

Combination treatment of Src inhibitor Saracatinib with GMI, a Ganoderma microsporum immunomodulatory protein, induce synthetic lethality via autophagy and apoptosis in lung cancer cells

Saracatinib is an oral Src-kinase inhibitor and has been studied in preclinical models and clinical trials of cancer therapy. GMI, a fungal immunomodulatory protein from Ganoderma microsporum, possesses antitumor capacity. The aim of this study is to evaluate the cytotoxic effect of combination treatment with saracatinib and GMI on parental and pemetrexed-resistant lung cancer cells. Cotreatment with saracatinib and GMI induced synergistic and additive cytotoxic effect in A549 and A400 cells by annexin V/propidium iodide assay and combination index. Using western blot assay, saracatinib, and GMI combined treatment synergistically induced caspase-7 activation in A549 cells. Different from A549 cells, saracatinib and GMI cotreatment markedly increased LC3B-II in A400 cells. ATG5 silencing abolished the caspase-7 activation and reduced cell death in A549 cells after cotreatment. This is the first study to provide a novel strategy of treating lung cancer with or without drug resistance via combination treatment with GMI and saracatinib.

miR-363 suppresses the proliferation, migration and invasion of clear cell renal cell carcinoma by downregulating S1PR1

Background

MicroRNAs (miRNAs) serve as important regulators of the tumorigenesis and progression of many human cancers. Therefore, we evaluated the biological function and underlying mechanism of miR-363 in clear cell renal cell carcinoma (ccRCC).

Methods

The expression of miR-363 in ccRCC tissues compared with adjacent normal renal tissues was detected by quantitative real-time polymerase chain reaction, and the association between miR-363 levels and prognosis of ccRCC patients was analyzed. The candidate target gene of miR-363 was determined by in silico analysis and luciferase reporter assays. The effects of miR-363 on the proliferation, migration and invasion of ccRCC cells in vitro were determined by MTS assay, colony formation assay, Transwell assay and wound healing assay. We also investigated the roles of miR-363 in vivo by a xenograft tumour model. The mechanism of miR-363 on the proliferation, migration and invasion of ccRCC was determined by gain- and loss-of-function analyses.

Results

we demonstrated that miR-363 expression was obviously downregulated in ccRCC tissues and that reduced miR-363 expression was correlated with poor disease-free survival (DFS) in ccRCC patients after surgery. S1PR1 expression was inversely correlated with the level of miR-363 in human ccRCC samples. Luciferase reporter assays suggested that S1PR1 was a direct functional target of miR-363. miR-363 downregulated S1PR1 expression and suppressed the proliferation, migration and invasion abilities of ccRCC cells in vitro and suppressed xenograft tumour growth in vivo. Importantly, miR-363 exerted its biological function by inhibiting S1PR1 expression in ccRCC cells, leading to the repression of ERK activation. Moreover, we found that the levels of downstream effectors of ERK, including PDGF-A, PDGF-B, and epithelial-mesenchymal transition (EMT)-related genes, were decreased after miR-363 overexpression.

Conclusions

Our results suggest that miR-363 acts as a tumour suppressor by directly targeting S1PR1 in ccRCC and may be a potential new therapeutic target for ccRCC.

RNAseq profiling of circRNA expression in radiation-treated A549 cells and bioinformatics analysis of radiation-related circRNA-miRNA networks

With the development of new biochemical and computational methods, circular RNAs (circRNAs) have been identified as microRNA sponges. circRNAs are associated with many diseases, particularly cancer. The present study aimed to investigate the expression profile of circRNAs in irradiated A549 lung cancer cells using high-throughput sequencing. Bioinformatics analyses were used to examine the potential functions of circRNAs. RNA sequencing data demonstrated that 1,875 circRNA targets were differentially expressed in A549 cells in response to irradiation. A total of 30 circRNAs were upregulated and 37 circRNAs were downregulated significantly in irradiation-treated A549 cells (fold change ≥2.0; P<0.05). The top 5 upregulated and downregulated circRNAs were successfully validated by reverse transcription-quantitative PCR. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that differentially expressed circRNAs might be pivotal in biological irradiation responses to irradiation. circRNA-microRNA co-expression networks highlighted the biological significance of circRNA_0002174 and circRNA_0036627, which require further study. In conclusion, the present study is, to the best of the authors' knowledge, the first to describe the differentially expressed profile of circRNAs in response to irradiation in A549 cells. These results provide a new perspective to elucidate insight into the molecular mechanisms by which A549 cells respond to radiation, and a basis for a more in-depth analysis of the potential application of circRNAs in the treatment of lung cancer therapy.

CD133 inhibition via autophagic degradation in pemetrexed-resistant lung cancer cells by GMI, a fungal immunomodulatory protein from Ganoderma microsporum

Background

Adaptive drug resistance is an unfavourable prognostic factor in cancer therapy. Pemetrexed-resistant lung cancer cells possess high-metastatic ability via ERK–ZEB1 pathway-activated epithelial–mesenchymal transition. GMI is a fungal immunomodulatory protein that suppresses the survival of several cancer cells.

Methods

Cell viability was analysed by MTT, clonogenic, tumour spheroid, and cancer stem cell sphere assays. Western blot assay was performed to detect the protein expression. Chemical inhibitors and ATG5 shRNA were used to inhibit autophagy. Tumour growth was investigated using xenograft mouse model.

Results

GMI decreased the viability with short- and long-term effects and induced autophagy but not apoptosis in A549/A400 cells. GMI downregulated the expression levels of CD133, CD44, NANOG and OCT4. GMI induces the protein degradation of CD133 via autophagy. CD133 silencing decreased the survival and proliferation of A549/A400 cells. GMI suppressed the growth and CD133 expression of A549/A400 xenograft tumour.

Conclusions

This study is the first to reveal the novel function of GMI in eliciting cytotoxic effect and inhibiting CD133 expression in pemetrexed-resistant lung cancer cells via autophagy. Our finding provides evidence that CD133 is a potential target for cancer therapy.

Down-Regulation of ZEB1 by miR-199a-3p Overexpression Restrains Tumor Stem-Like Properties and Mitochondrial Function of Non-Small Cell Lung Cancer

OBJECTIVE

MicroRNA-199a-3p (miR-199a-3p or miR-199b-3p) targeting of 3'-UTR of ZEB1 was characterized as an important way to inhibit invasion and metastases in non-small cell lung cancer (NSCLC), one of the most common cancers around the world. Here we aimed to investigate the tumor-suppressive role of miR-199a-3p targeted ZEB1.

MATERIALS AND METHODS

A549 cells were transfected with ZEB1 and/or miR-199a-3p. Then, tumor growth was investigated in xenograft mice. Stem-like property, proliferation and mitochondria injury were further validated in vitro.

RESULTS

Overexpression of miR-199a-3p with premiRNAs significantly reduced tumor growth inhibited CD44 and Ki67 and increased Caspase-3 in A549 xenograft mice. Sphere formation and protein expression of stem-like markers showed that miR-199a-3p inhibited stemness of A549 cell. miR-199a-3p reduced proliferation of A549 cells, as showed with EdU staining and reduced expression of Ki67. Transfection of miR-199a-3p also promoted apoptosis, as indicated with increased apoptotic cells with flow cytometry, and increased cleaved Caspase-3/Caspase3 and Bcl-2/Bax. Apoptosis was further validated to be induced with mitochondria dysfunction, which indicated with JC-1 labeled loss of mitochondrial membrane potential, reduced activity of SOD, and increased MDA and LDH. All these effects were inverted with overexpression of ZEB1.

CONCLUSION

Altogether, the findings suggested that the up-regulation of miR-199a-3p significantly inhibited NSCLC growth in vivo, and reduced A549 cell proliferation and promoted mitochondrial-mediated apoptosis, through down-regulation of ZEB1. The findings supported ZEB1 down-expression with miR-199a-3p as a novel therapeutic target for NSCLC treatment.

Anti-tubulin agent vinorelbine inhibits metastasis of cancer cells by regulating epithelial-mesenchymal transition

Cancer invasion and metastasis are the leading causes of death. The process of metastasis or tumor cell dissemination is still much of a mystery. Emerging evidence has shown that epithelial-mesenchymal transition (EMT) plays a vital role in the progression of malignant tumor including the inducing cell invasion and metastasis as well as promoting drug resistance. Vinorelbine is a traditional chemotherapeutic agent for treatment of lung cancer and breast cancer by the selectivity to mitotic microtubules. The aim of this study was to investigate the effect of vinorelbine on three metastatic cancer cells including lung cancer (H1975), liver cancer (HepG2), and colon cancer (HCT116) cells through inhibition of metastatic abilities and EMT program. Vinorelbine inhibited the cancer cell proliferation by MTT and colony formation assays and inducing G2/M arrest and cell apoptosis via regulation of Bax, Bcl-2, and Bcl-xL. Vinorelbine decrease the migration and invasion ability of the cancer cells by wound healing assay and Tran swell test. The molecular mechanisms of vinorelbine suppressing the metastatic phenotypes of cancer cells through modulation of E-cadherin, N-cadherin, vimentin and transcription factors Snail, MMP-2 and MMP-9. Our results demonstrated that vinorelbine inhibited the cancer cell metastasis through a reduction in metastatic mobility, such as migration, invasion, and the EMT. It provided the evidence that vinorelbine can be used alone or with other agents for treatment of metastatic lung cancer, liver cancer and colon cancer.

Hypoxia-Induced Epithelial-Mesenchymal Transition in Cancers: HIF-1α and Beyond

Metastasis is the main cause of cancer-related mortality. Although the actual process of metastasis remains largely elusive, epithelial-mesenchymal transition (EMT) has been considered as a major event in metastasis. Besides, hypoxia is common in solid cancers and has been considered as an important factor for adverse treatment outcomes including metastasis. Since EMT and hypoxia potentially share several signaling pathways, many recent studies focused on investigate the issue of hypoxia-induced EMT. Among all potential mediators of hypoxia-induced EMT, hypoxia-inducible factor-1α (HIF-1α) has been studied extensively. Moreover, there are other potential mediators that may also contribute to the process. This review aims to summarize the recent reports on hypoxia-induced EMT by HIF-1α or other potential mediators and provide insights for further investigations on this issue. Ultimately, better understanding of hypoxia-induced EMT may allow us to develop anti-metastatic strategies and improve treatment outcomes.