Epithelial–mesenchymal transition in human cancer: Comprehensive reprogramming of metabolism, epigenetics, and differentiation

Long noncoding RNA H19 regulates EZH2 expression by interacting with miR-630 and promotes cell invasion in nasopharyngeal carcinoma

The long non-coding RNA (lncRNA) H19 has been recently shown to participate in the progression of cancer, including metastasis. However, the biological role of H19 and the underlying mechanisms mediating its functions in nasopharyngeal carcinoma (NPC) remain unclear. Herein, we found that H19 was overexpressed in NPC tissues and poorly differentiated cell lines. Knockdown of H19 significantly inhibited the invasive ability of NPC cells. Moreover, H19 affected the expression of enhancer of zeste homolog 2 (EZH2), which has also been observed to be up-regulated in NPC and to promote cell invasion. Rather than direct interaction, H19 regulated EZH2 expression by suppressing the activity of miR-630, which is a repressor of EZH2 and interacts with H19 in a sequence-specific manner. Furthermore, H19 inhibited E-cadherin expression and promoted cell invasion of NPC cells via the miR-630/EZH2 pathway. Our data suggest an important role for H19 in NPC metastasis and suggest the feasibility of therapy for NPC involving modulation of the novel regulatory network.

Zinc finger E-box-binding homeobox 1: its clinical significance and functional role in human thyroid cancer

Objective

Transcription factor zinc finger E-box-binding homeobox 1 (ZEB1), as one of the key inducers of epithelial-mesenchymal transition, has been reported to be regulated by microRNA-144 and Bcl-2-associated athanogene 3, which both promote thyroid cancer cell invasion. However, the involvement of ZEB1 in thyroid cancer has not been fully elucidated. In this study, we aimed to investigate the role and clinical implication of ZEB1 in this disease.

Methods

Immunohistochemistry was performed to examine the subcellular localization and the expression level of ZEB1 protein in 82 self-pairs of formalin-fixed and paraffin-embedded cancerous and adjacent noncancerous tissues obtained from patients with thyroid cancer. The roles of ZEB1 in thyroid cancer cell migration, invasion, and proliferation were also detected by transwell and MTT analyses, respectively.

Results

Immunohistochemistry showed that ZEB1 was predominantly localized in the nucleus of thyroid cancer cells. Its immunoreactive score in thyroid cancer tissues was significantly higher than that in adjacent noncancerous tissues (P=0.01). In addition, ZEB1 overexpression was significantly associated with the advanced tumor node metastasis staging (P=0.008), the positive lymph node metastasis (P=0.01) and distant metastasis (P=0.02). Furthermore, ZEB1 knockdown by siRNA could efficiently inhibit the migration, invasion, and proliferation abilities of thyroid cancer cells in vitro.

Conclusion

These findings indicated that ZEB1 might function as an oncogene, the overexpression of which was associated with the aggressive tumor progression of human thyroid cancer. Interestingly, ZEB1 also could promote thyroid cancer cell migration, invasion, and proliferation, suggesting that the inhibition of this protein might be a therapeutic strategy for the treatment of this malignancy.

miR-27a-3p suppresses tumor metastasis and VM by down-regulating VE-cadherin expression and inhibiting EMT: an essential role for Twist-1 in HCC

Twist-1 and miRNAs have been reported to be associated with tumor metastasis and angiogenesis. However, the relationship between Twist-1 and miRNAs and the function of miRNAs remain largely undefined. We aimed to reveal the Twist-1-related miRNA expression profile and to determine whether Twist-1 functions in tumor metastasis and vasculogenic mimicry (VM) by regulating miRNA expression in hepatocellular carcinoma (HCC). Results showed that the expression of miR-27a-3p was consistently down-regulated in HCC cell lines and tissue samples displaying high expression of Twist-1. Both loss- and gain-of-function assays revealed suppressive effects of miR-27a-3p. Low miR-27a-3p expression was significantly associated with early metastasis in HCC. Subsequent investigations revealed that miR-27a-3p mediated the inhibition of epithelial–mesenchymal transition (EMT). Additional experiments showed that VE-cadherin is a direct target of miR-27a-3p and further demonstrated the critical role of miR-27a-3p in suppressing tumor metastasis and VM. Conclusions: Twist-1 up-regulation in HepG2 cells resulted in the differential expression of 18 miRNAs. Among them, miR-27a-3p deregulation contributed to VM and metastasis. The miR-27a-3p-mediated down-regulation of VE-cadherin and inhibition of EMT may be essential for Twist-1 to induce tumor metastasis and VM. Our findings highlight the importance of miR-27a-3p and suggest a promising new strategy for anti-HCC therapy.

Pharmacoproteomic analysis reveals that metapristone (RU486 metabolite) intervenes E-cadherin and vimentin to realize cancer metastasis chemoprevention

Metapristone is the most predominant biological active metabolite of mifepristone, and being developed as a novel cancer metastasis chemopreventive agent by us. Despite its prominent metastasis chemopreventive effect, the underlying mechanism remains elusive. Our study, for the first time, demonstrated that metapristone had the ability to prevent breast cancer cells from migration, invasion, and interfere with their adhesion to endothelial cells. To explore the underlying mechanism of metapristone, we employed the iTRAQ technique to assess the effect of metapristone on MDA-MB-231 cells. In total, 5,145 proteins were identified, of which, 311 proteins showed significant differences in metapristone-treated cells compared to the control group (P-value < 0.05). Bioinformatic analysis showed many differentially expressed proteins (DEPs) functionally associated with post-translational modification, chaperones, translation, transcription, replication, signal transduction, etc. Importantly, many of the DEPs, such as E-cadherin, vimentin, TGF-β receptor I/II, smad2/3, β-catenin, caveolin, and dystroglycan were associated with TGF-β and Wnt signaling pathways, which were also linked to epithelial-to-mesenchymal transition (EMT) process. Further validation of the epithelial marker "E-caderin" and mesenchymal marker "vimetin" were carried out using immunoblot and immunofluorescence. These results have revealed a novel mechanism that metapristone-mediated metastasis chemoprevention is through intervening the EMT-related signaling pathways.

Glyoxalase I drives epithelial-to-mesenchymal transition via argpyrimidine-modified Hsp70, miR-21 and SMAD signalling in human bronchial cells BEAS-2B chronically exposed to crystalline silica Min-U-Sil 5: Transformation into a neoplastic-like phenotype

Glyoxalase I (Glo1) is the main scavenging enzyme of methylglyoxal (MG), a potent precursor of advanced glycation end products (AGEs). AGEs are known to control multiple biological processes, including epithelial to mesenchymal transition (EMT), a multistep phenomenon associated with cell transformation, playing a major role in a variety of diseases, including cancer. Crystalline silica is a well-known occupational health hazard, responsible for a great number of human pulmonary diseases, such as silicosis. There is still much debate concerning the carcinogenic role of crystalline silica, mainly due to the lack of a causal demonstration between silica exposure and carcinogenesis. It has been suggested that EMT might play a role in crystalline silica-induced lung neoplastic transformation. The aim of this study was to investigate whether, and by means of which mechanism, the antiglycation defence Glo1 is involved in Min-U-Sil 5 (MS5) crystalline silica-induced EMT in BEAS-2B human bronchial epithelial cells chronically exposed, and whether this is associated with the beginning of a neoplastic-like transformation process. By using gene silencing/overexpression and scavenging/inhibitory agents, we demonstrated that MS5 induced hydrogen peroxide-mediated c-Jun-dependent Glo1 up-regulation which resulted in a decrease in the Argpyrimidine-modified Hsp70 protein level which triggered EMT in a novel mechanism involving miR-21 and SMAD signalling. The observed EMT was associated with a neoplastic-like phenotype. The results obtained provide a causal in vitro demonstration of the MS5 pro-carcinogenic transforming role and more importantly they provide new insights into the mechanisms involved in this process, thus opening new paths in research concerning the in vivo study of the carcinogenic potential of crystalline silica.

Long noncoding RNA ENST00000434223 suppressed tumor progression in non-small cell lung cancer

In spite of the fact that the great progress has been made in the treatment of non-small cell lung cancer (NSCLC), the prognosis of NSCLC remains comparatively dismal. Therefore, it is of great value to identify novel effective diagnostic biomarkers and therapeutic targets of NSCLC. Emerging evidence has demonstrated the vital roles of long noncoding RNAs (lncRNAs) in cancer development. ENST00000434223 was recently identified as a lncRNA that is downregulated in early stage lung adenocarcinoma in a profiling study. However, little is known about its role in the development of NSCLC. In the present study, we found that ENST00000434223 was greatly downregulated in cancer tissues compared to adjacent normal tissues. ENST00000434223 overexpression suppressed the proliferation and migration in NSCLC cell lines in vitro. Moreover, ENST00000434223 overexpression reversed the epithelial-mesenchymal transition in NSCLC cell line. Our study suggests that ENST00000434223 may be a potential biomarker and a therapeutic target of NSCLC.

LRG1 modulates epithelial-mesenchymal transition and angiogenesis in colorectal cancer via HIF-1α activation

Background

Leucine-rich-alpha-2-glycoprotein 1 (LRG1) has been reported to be involved in several tumors, whether it participates in colorectal cancer (CRC) progression remains unclear. Here, we investigated the biological function and underlying molecular mechanisms of LRG1 in CRC.

Methods

The mRNA and protein levels of LRG1 were assessed in CRC tissues through RT-PCR and immunohistochemistry, respectively. HCT116 and SW480 cells were treated with LRG1 siRNA, control siRNA, or recombinant LRG1. Transwell invasion assays and wound healing assays were performed to evaluate the invasion and migration of CRC cells. Epithelial-to-mesenchymal transition (EMT) markers of E-cadherin, VDR, N-cadherin, α-SMA, Vimentin and Twist1 were detected by RT-PCR and western blot. Enzyme-linked immunosorbent assay was used to measure the secretion level of VEGF-A. Conditioned medium from CRC cells was collected for endothelial cell migration, tube formation and aortic ring sprouting assays.

Results

LRG1 was overexpressed in CRC tissues and associated with cancer aggressiveness. LRG1 was further found to induce the EMT process, as well as CRC cell migration and invasion capacity. In addition, LRG1 promoted VEGF-A expression in CRC cells and contributed to tumor angiogenesis. Furthermore, HIF-1α could be induced by LRG1 in a concentration- and time-dependent manner, which was responsible for LRG1-induced VEGF-A expression and EMT.

Conclusions

The present study suggests that LRG1 plays a crucial role in the progression of CRC by regulating HIF-1α expression, thereby may be a promising therapeutic target of CRC.

Transducin (Beta)-Like 1 X-Linked Receptor 1 Correlates with Clinical Prognosis and Epithelial-Mesenchymal Transition in Hepatocellular Carcinoma

BACKGROUND

Recent studies have demonstrated that transducin (beta)-like 1 X-linked receptor 1 (TBLR1) is involved in tumor progression. However, the exact role and clinical significance of TBLR1 in hepatocellular carcinoma (HCC) are poorly understood.

AIM

In this study, we aimed to investigate the expression and clinical significance of TBLR1 in HCC.

METHODS

Quantitative polymerase chain reaction and immunohistochemical staining were performed to detect the expression levels of TBLR1 in HCC tissue and adjacent noncancerous tissue (ANT). The relationships between TBLR1 expression and clinicopathological factors were examined in this study. The effects of TBLR1 on epithelial-mesenchymal transition (EMT) of HCC cells were investigated in vitro.

RESULTS

The expression levels of TBLR1 were elevated in HCC cell lines. TBLR1 mRNA in HCC tissue was markedly higher (P < 0.001) than that in ANT. High expression of TBLR1 is closely related to serum alpha fetoprotein (P = 0.047), BCLC stage (P < 0.001), maximum size of tumors (P < 0.001), tumor embolus (P < 0.001), and histological grade (P < 0.001). The disease-free survival and overall survival of HCC patients with high expression of TBLR1 were significantly shorter. Furthermore, we found that EMT of HCC cells could be induced by up-regulating TBLR1 and be inhibited by down-regulating TBLR1. ICG-001, the inhibitor of Wnt/β-catenin signaling, could suppress induction of EMT mediated by TBLR1.

CONCLUSIONS

Our finding suggested that TBLR1 is likely to be a potential prognostic indicator and therapeutic target for HCC and that TBLR1 may be implicated in EMT of HCC cells.

MicroRNAs and Cancer Drug Resistance

The discovery of small regulatory noncoding RNAs revolutionized our thinking on gene regulation. The class of microRNAs (miRs), a group of small noncoding RNAs (20-22 nt in length) that bind imperfectly to the 3'-untranslated region of target mRNA, has been insistently implicated in several pathological conditions including cancer. Indeed, major hallmarks of cancer, such as cell differentiation, cell proliferation, cell cycle, cell survival, and cell invasion, has been described as being regulated by miRs. Recent studies have also implicated miRs in cancer drug resistance. Regardless of the several studies done until now, drug resistance still is a burden for cancer therapy and patients' outcome, often resulting in more aggressive tumors that tend to metastasize to distant organs. Hence, with this review, we aim to summarize the miRs that influence molecular pathways that are involved in cancer drug resistance, such as drug metabolism, drug influx/efflux, DNA damage response (DDR), epithelial-to-mesenchymal transition (EMT), and cancer stem cells.

Targeting tumor metastases: Drug delivery mechanisms and technologies

Primary sites of tumor are the focal triggers of cancers, yet it is the subsequent metastasis events that cause the majority of the morbidity and mortality. Metastatic tumor cells exhibit a phenotype that differs from that of the parent cells, as they represent a resistant, invasive subpopulation of the original tumor, may have acquired additional genetic or epigenetic alterations under exposure to prior chemotherapeutic or radiotherapeutic treatments, and reside in a microenvironment differing from that of its origin. This combination of resistant phenotype and distal location make tracking and treating metastases particularly challenging. In this review, we highlight some of the unique biological traits of metastasis, which in turn, inspire emerging strategies for targeted imaging of metastasized tumors and metastasis-directed delivery of therapeutics.

CCL18/PITPNM3 enhances migration, invasion, and EMT through the NF-κB signaling pathway in hepatocellular carcinoma

Chemokine ligand 18 (CCL18) has been associated with hepatocellular carcinoma (HCC) metastasis. Here, we demonstrated a novel mechanism through which CCL18 enhances cell migration, invasion, and epithelial-mesenchymal transition (EMT) in HCC. (1) Using immunohistochemistry, we analyzed the expression of PITPNM3, a molecule that correlated with CCL18 signaling, in 149 HCC tissue specimens. The results showed that PITPNM3 expression is highly associated with tumor metastasis and differentiation; (2) in vitro experiments showed that CCL18 enhances cell migration, invasion, and EMT in PITPNM3((+)) HCC cells but not in PITPNM3((-)) cells. Silencing of PITPNM3 by short interfering RNA (siRNA) inhibited the induction of cell migration, invasion, and EMT by CCL18; (3) Cell migration, invasion, and EMT induced by CCL18 accompanied with the phosphorylation of IKK and IKBα as well as p65 nuclear translocation in PITPNM3((+)) HCC cells, but not in the cells that PITPNM3 is silenced with siRNA, implying that the activation of NF-κB signaling is involved in the action of CCL18/PITPNM3. These results suggest that CCL18 enhances HCC cell migration, invasion, and EMT through the expression of PITPNM3 and the activation of the NF-κB signaling pathway.

F-box protein interactions with the hallmark pathways in cancer

F-box proteins (FBP) are the substrate specifying subunit of Skp1-Cul1-FBP (SCF)-type E3 ubiquitin ligases and are responsible for directing the ubiquitination of numerous proteins essential for cellular function. Due to their ability to regulate the expression and activity of oncogenes and tumour suppressor genes, FBPs themselves play important roles in cancer development and progression. In this review, we provide a comprehensive overview of FBPs and their targets in relation to their interaction with the hallmarks of cancer cell biology, including the regulation of proliferation, epigenetics, migration and invasion, metabolism, angiogenesis, cell death and DNA damage responses. Each cancer hallmark is revealed to have multiple FBPs which converge on common signalling hubs or response pathways. We also highlight the complex regulatory interplay between SCF-type ligases and other ubiquitin ligases. We suggest six highly interconnected FBPs affecting multiple cancer hallmarks, which may prove sensible candidates for therapeutic intervention.

Stemness and chemotherapeutic drug resistance induced by EIF5A2 overexpression in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies of the digestive tract in East Asian countries. Multimodal therapies, including adjuvant chemotherapy and neo-adjuvant chemotherapy, have become more often used for patients with advanced ESCC. However, the chemotherapy effect is often limited by patients' drug resistance. This study demonstrated that EIF5A2 (eukaryotic translation initiation factor 5A2) overexpression induced stemness and chemoresistance in ESCC cells. We showed that EIF5A2 overexpression in ESCC cells resulted in increased chemoresistance to 5-fluorouracil (5-FU), docetaxel and taxol. In contrast, shRNAs suppressing eIF5A2 increased tumor sensitivity to these chemotherapeutic drugs. In addition, EIF5A2 overexpression was correlated with a poorer overall survival in patients with ESCC who underwent taxane-based chemotherapy after esophagectomy (P < 0.05). Based on these results, we suggest that EIF5A2 could be a predictive biomarker for selecting appropriate chemo-treatment for ESCC patients and EIF5A2 inhibitors might be considered as combination therapy to enhance chemosensitivity in patients with ESCC.

The Potential Role of Hedgehog Signaling in the Luminal/Basal Phenotype of Breast Epithelia and in Breast Cancer Invasion and Metastasis

The epithelium of the lactiferous ducts in the breast is comprised of luminal epithelial cells and underlying basal myoepithelial cells. The regulation of cell fate and transit of cells between these two cell types remains poorly understood. This relationship becomes of greater importance when studying the subtypes of epithelial breast carcinoma, which are categorized according to their expression of luminal or basal markers. The epithelial mesenchymal transition (EMT) is a pivotal event in tumor invasion. It is important to understand mechanisms that regulate this process, which bears relation to the normal dynamic of epithelial/basal phenotype regulation in the mammary gland. Understanding this process could provide answers for the regulation of EMT in breast cancer, and thereby identify potential targets for therapy. Evidence points towards a role for hedgehog signaling in breast tissue homeostasis and also in mammary neoplasia. This review examines our current understanding of role of the hedgehog-signaling (Hh) pathway in breast epithelial cells both during breast development and homeostasis and to assess the potential misappropriation of Hh signals in breast neoplasia, cancer stem cells and tumor metastasis via EMT.

Possible role of vitamin D3 on the adipocyte/fibroblast trans-differentiation mediated by pancreas cancer

In pancreatic tumors, white adipose tissue and metabolic disorders related to adipocytes, are recently reviewed as important co-factors in pancreas pathology. Cell differentiation in pancreatic cancer might involve therefore adipose tissue and factors released by adipocytes should play a fundamental role both in cancer onset and in its progression. Among these molecules, a great interest has been devoted quite recently to the hormonal role exerted by vitamin D3 in pancreatic cancer, particularly its active 1,25 dihydroxylated form. Despite the wide bulk of evidence reporting the chemopreventive role of vitamin D, the mechanism by which active vitamin D3 is able to counteract cancer progression and malignancy is yet far to be elucidated.