Hypoxia-induced LncRNA PCGEM1 promotes invasion and metastasis of gastric cancer through regulating SNAI1

PURPOSE

Hypoxia is an indispensable factor in the progression of metastasis. Hypoxia inducible factor-1α (HIF-1α), the core element in generating the hypoxia response, induces invasion and metastasis by promoting epithelial-mesenchymal transition (EMT). This study explored the underlying mechanism of hypoxia associated with the invasion and metastasis of gastric cancer (GC).

METHODS

Six methods were employed to assess the function of the long noncoding RNA (lncRNA) prostate cancer gene expression marker 1 (PCGEM1) including gene silencing, RT-PCR, the separation of nuclear and cytoplasmic fractions, scrape motility assay, transwell migration assay, and Western-blot.

RESULTS

LncRNA PCGEM1 was overexpressed in GC cells and tissues, and was induced by hypoxia in GC cells. Additional experiments confirmed that the knockdown of PCGEM1 significantly repressed the invasion and metastasis of GC cells. SNAI1, a key transcription factor of EMT, was regulated by PCGEM1. Overexpression of SNAI1 rescued the inhibition of PCGEM1-knockdown during the invasion and metastasis of GC cells. In addition, PCGEM1 and SNAI1 jointly affected the biomarkers of EMT.

CONCLUSION

Our findings indicated that PCGEM1 is a hypoxia-responsive lncRNA, and contributes to the invasion and metastasis of GC. The potential mechanism is attributed to the regulation of EMT by PCGEM1 and its influence on the expression of SNAI1.

PGC-1α/SNAI1 axis regulates tumor growth and metastasis by targeting miR-128b in gastric cancer

Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is a transcriptional coactivator that has been characterized as master regulators of mitochondrial biogenesis. It has been reported that aberrant regulation of PGC-1α is involved in a variety of human cancers. However, whether PGC-1α is involved in the regulation of tumor growth and metastasis in gastric cancer (GC) remains unknown. In the present study, we found that the expression of PGC-1α was upregulated in GC tissues and GC cell lines. Inhibition of PGC-1α inhibited cell viability, migration, and invasion, and promoted cell apoptosis of GC cells. Furthermore, inhibition of PGC-1α downregulated the SNAI1 expression, whereas upregulated microRNA (miR)-128b expression. The expression of SNAI1 was upregulated and the expression of miR-128b was downregulated in GC tissues. We further found that there was a positive correlation between PGC-1α and SNAI1 expression, and a negative correlation between PGC-1α and miR-128b expression or between SNAI1 and miR-128b expression in GC tissues. Moreover, PGC-1α inhibition-induced increased miR-128b expression, and PGC-1α overexpression-induced decreased miR-128b expression were both markedly suppressed by SNAI1 overexpression. In addition, SNAI1 overexpression or miR-128b inhibition partly reversed the effects of PGC-1α inhibition in GC cells. Furthermore, inhibition of PGC-1α suppressed the tumor growth in a nude mouse model, which may be related with the dysregulation of SNAI1 and miR-128b. In conclusion, these data indicate that the PGC-1α/SNAI1/miR-128b axis plays a vital role in GC via regulating cell viability, migration, invasion, and apoptosis.

The histone H3 Lys 27 demethylase KDM6B promotes migration and invasion of glioma cells partly by regulating the expression of SNAI1

The histone demethylase KDM6B, also known as jumonji domain-containing protein 3 (JMJD3), is an epigenetic regulator which plays important roles in immune activation, tissue regeneration, cellular senescence and cancer metastasis. But, the role of KDM6B in glioma metastasis is poorly understood. In this study, we achieved transcriptional regulation of KDM6B in glioma cells using CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa). Our results showed that KDM6B promotes the proliferation, migration and invasion of human glioblastoma cells U87 and U251 using CCK8, scratch and transwell assays. Further results indicated that KDM6B increases the expression of SNAI1, a key factor of epithelial-mesenchymal transition (EMT). KDM6B catalyzes the demethylation of histone H3 Lys 27 trimethylation (H3K27me3) in the promoter of SNAI1, which is important for SNAI1 upregulation. Taken together, these findings provide new insight into the mechanism by which KDM6B promotes glioma metastasis.

MiR-940 inhibits TGF-β-induced epithelial-mesenchymal transition and cell invasion by targeting Snail in non-small cell lung cancer

Increased evidence reveals that miR-940 inhibits the migration and invasion of cancer cells. Considering transforming growth factor β (TGF-β) signaling is crucial to cellular epithelial-mesenchymal transition (EMT) process and metastasis of cancer, it is in urgent to explore whether and how miR-940 plays an essential role in regulating TGF-β-induced EMT in lung cancer progression. In the present study, we observed a reciprocal expression with down-regulated miR-940 and up-regulated Snail mRNA in non-small-cell lung cancer (NSCLC) tissues. we further found that the expression of miR-940 was decreased in NSCLC tissues with lymph node metastasis, advanced TNM stages and poor cell differentiation, in which, on the contrary, the expression of Snail was increased. Overexpression of miR-940 significantly inhibited Snail mRNA and protein expression in A549 and H226 cells. Mechanistically, Snail mRNA was identified as target of miR-940. In addition, miR-940 repressed TGF-β-induced EMT and further hampered the cell migration and invasion. Finally, siRNA-mediated knockdown of Snail copied the phenotype of miR-940 overexpression in A549 and H226 cells. Taken together, our study reveals that miR-940 can suppress TGF-β-induced EMT and cell invasion by targeting Snail 3'-UTR mRNA in NSCLC.

MicroRNA-153 suppresses cell invasion by targeting SNAI1 and predicts patient prognosis in glioma

Glioma is the most common and rapidly progressive type of malignant primary brain tumor in adults. miR-153 plays a major role in many malignancies; nevertheless, few studies have been conducted on glioma. The aim of the present study was to explore the role of miR-153 and SNAI1 on invasion in glioma. Reverse transcription-quantitative PCR was employed to measure the expression levels of miR-153 and SNAI1 mRNA. Transwell assay was utilized to calculate the capacity of invasion. Luciferase report assay was applied to detect whether SNAI1 was a target of miR-153. miR-153 was downregulated in glioma tissues and cells versus paracancerous tissues and normal immortalized gliocyte HEB cells. Transwell assay was used to measure whether a low expression of miR-153 in glioma indicated inhibition of cell invasion. We verified that SNAI1 was a target of miR-153 and had a negative association with miR-153 detected by luciferase reporter assay. Additionally, miR-153 suppressed cell invasive ability by regulating SNAI1 expression, whose partial function was reversed by SNAI1. miR-153 suppressed cell invasion of glioma by directly targeting SNAI1. Thus, miR-153/SNAI1 axis may be a novel target for cervical cancer treatment.

CircRBMS3 promotes gastric cancer tumorigenesis by regulating miR-153-SNAI1 axis

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. Mounting evidence showed that circular RNAs (circRNAs) play critical roles in human malignancy. However, the knowledge about circRNAs in GC is still unclear. In the current study, high throughput microarray assay showed that circRBMS3 was upregulated in GC tissues, which was further confirmed by quantitative reverse transcription polymerase chain reaction. Correlation analysis revealed that high circRBMS3 expression was associated with advanced TNM stage, depth of invasion, and lymph-node metastasis. Kaplan-Meier analysis indicated that GC patients with high circRBMS3 expression have a poor overall survival (OS). Function assays showed that circRBMS3 silencing reduced GC cells proliferation and invasion in vitro, and inhibited the tumor growth in vivo. Mechanistically, we found that miR-153 could act as a target of circRBMS3. Subsequently, we showed that circRBMS3 promoted snail family zinc finger 1 (SNAI1) expression via inhibiting miR-153 in GC cells. Collectively, these results suggested that circRBMS3 promoted GC cells proliferation and invasion via regulating miR-153/SNAI1 axis.

The NOTCH1/SNAIL1/MEF2C Pathway Regulates Growth and Self-Renewal in Embryonal Rhabdomyosarcoma

Tumor-propagating cells (TPCs) share self-renewal properties with normal stem cells and drive continued tumor growth. However, mechanisms regulating TPC self-renewal are largely unknown, especially in embryonal rhabdomyosarcoma (ERMS)-a common pediatric cancer of muscle. Here, we used a zebrafish transgenic model of ERMS to identify a role for intracellular NOTCH1 (ICN1) in increasing TPCs by 23-fold. ICN1 expanded TPCs by enabling the de-differentiation of zebrafish ERMS cells into self-renewing myf5+ TPCs, breaking the rigid differentiation hierarchies reported in normal muscle. ICN1 also had conserved roles in regulating human ERMS self-renewal and growth. Mechanistically, ICN1 upregulated expression of SNAIL1, a transcriptional repressor, to increase TPC number in human ERMS and to block muscle differentiation through suppressing MEF2C, a myogenic differentiation transcription factor. Our data implicate the NOTCH1/SNAI1/MEF2C signaling axis as a major determinant of TPC self-renewal and differentiation in ERMS, raising hope of therapeutically targeting this pathway in the future.

miR-145 Antagonizes SNAI1-Mediated Stemness and Radiation Resistance in Colorectal Cancer

Epithelial-to-mesenchymal transition (EMT) has been closely linked with therapy resistance and cancer stem cells (CSCs). However, EMT pathways have proven challenging to therapeutically target. MicroRNA 145 (miR-145) targets multiple stem cell transcription factors and its expression is inversely correlated with EMT. Therefore, we hypothesized that miR-145 represents a therapeutic target to reverse snail family transcriptional repressor 1 (SNAI1)-mediated stemness and radiation resistance (RT). Stable expression of SNAI1 in DLD1 and HCT116 cells (DLD1-SNAI1; HCT116-SNAI1) increased expression of Nanog and decreased miR-145 expression compared to control cells. Using a miR-145 luciferase reporter assay, we determined that ectopic SNAI1 expression significantly repressed the miR-145 promoter. DLD1-SNAI1 and HCT116-SNAI1 cells demonstrated decreased RT sensitivity and, conversely, miR-145 replacement significantly enhanced RT sensitivity. Of the five parental colon cancer cell lines, SW620 cells demonstrated relatively high endogenous SNAI1 and low miR-145 levels. In the SW620 cells, miR-145 replacement decreased CSC-related transcription factor expression, spheroid formation, and radiation resistance. In rectal cancer patient-derived xenografts, CSC identified by EpCAM+/aldehyde dehydrogenase (ALDH)+ demonstrated high expression of SNAI1, c-Myc, and Nanog compared with non-CSCs (EpCAM+/ALDH-). Conversely, patient-derived CSCs demonstrated low miR-145 expression levels relative to non-CSCs. These results suggest that the SNAI1:miR-145 pathway represents a novel therapeutic target in colorectal cancer to overcome RT resistance.

MicroRNA-182 drives colonization and macroscopic metastasis via targeting its suppressor SNAI1 in breast cancer

Metastasis is a multi-step process. Tumor cells occur epithelial-mesenchymal transition (EMT) to start metastasis, then, they need to undergo a reverse progression of EMT, mesenchymal-epithelial transition (MET), to colonize and form macrometastases at distant organs to complete the whole process of metastasis. Although microRNAs (miRNAs) functions in EMT process are well established, their influence on colonization and macrometastases formation remains unclear. Here, we established an EMT model in MCF-10A cells with SNAI1 overexpression, and characterized some EMT-related microRNAs. We identified that miR-182, which was directly suppressed by SNAI1, could enable an epithelial-like state in breast cancer cells in vitro, and enhance colonization and macrometastases in vivo. Subsequent studies showed that miR-182 exerted its function through targeting its suppressor SNAI1. Moreover, higher expression level of miR-182 was detected in metastatic lymph nodes, compared with paired primary tumor tissues. In addition, the expression level of miR-182 was negatively correlated with that of SNAI1 in these clinical specimens. Taking together, our findings describe the role of miR-182 in colonization and macrometastases in breast cancer for the first time, and provide a promise for diagnosis or therapy of breast cancer metastasis.

Possible effect of SNAIL family transcriptional repressor 1 polymorphisms in non-syndromic cleft lip with or without cleft palate

OBJECTIVE

Orofacial development is a complex process subjected to failure impairing. Indeed, the cleft of the lip and/or of the palate is among the most frequent inborn malformations. The JARID2 gene has been suggested to be involved in non-syndromic cleft lip with or without cleft palate (nsCL/P) etiology. JARID2 interacts with the polycomb repressive complex 2 (PRC2) in regulating the expression patterns of developmental genes by modifying the chromatin state.

MATERIALS AND METHODS

Genes coding for the PRC2 components, as well as other genes active in cell differentiation and embryonic development, were selected for a family-based association study to verify their involvement in nsCL/P. A total of 632 families from Italy and Asia participated to the study.

RESULTS

Evidence of allelic association was found with polymorphisms of SNAI1; in particular, the rs16995010-G allele was undertransmitted to the nsCL/P cases [P = 0.004, odds ratio = 0.69 (95% C.I. 0.54-0.89)]. However, the adjusted significance value corrected for all the performed tests was P = 0.051.

CONCLUSIONS

The findings emerging by the present study suggest for the first time an involvement of SNAI1 in the nsCL/P onset.

CLINICAL RELEVANCE

Interestingly, SNAI1 is known to promote epithelial to mesenchymal transition by repressing E-cadherin expression, but it needs an intact PRC2 to act this function. Alterations of this process could contribute to the complex etiology of nsCL/P.

Fibroblast growth factor 2 induces proliferation and fibrosis via SNAI1-mediated activation of CDK2 and ZEB1 in corneal endothelium

Investigating stimulation of endogenous wound healing in corneal endothelial cells (CECs) may help address the global shortage of donor corneas by decreasing the number of transplants performed for blindness because of endothelial dysfunction. We previously reported that IL-1β stimulation leads to fibroblast growth factor (FGF2) expression, enhancing migration and proliferation of mammalian CECs. However, FGF2 also promotes the endothelial-mesenchymal transition, which can lead to retrocorneal membrane formation and blindness. This prompted us to investigate downstream FGF2 signaling targets that could be manipulated to prevent retrocorneal membrane formation. FGF2 stimulation altered cell morphology and induced expression of mesenchymal transition marker genes such as snail family transcriptional repressor 1 (SNAI1), SNAI2, zinc finger E-box-binding homeobox 1 (ZEB1), and ZEB2 This, in turn, induced expression of fibronectin, vimentin, and type I collagen, and suppressed E-cadherin in CECs in vitro and ex vivo siRNA-mediated SNAI1 knockdown revealed that SNAI1 induces ZEB1 expression, in turn inducing expression of type I collagen, the major component of retrocorneal membranes, and of cyclin-dependent kinase 2 (CDK2) and cyclin E1, promoting cell proliferation. siRNA-mediated knockdown of SNAI1 or ZEB1, but not of CDK2, inhibited FGF2-dependent expression of fibronectin, vimentin, and type I collagen and of suppression of E-cadherin expression. We conclude that SNAI1 is a key regulator of FGF2-dependent mesenchymal transition in human ex vivo corneal endothelium, with ZEB1 regulating type I collagen expression and CDK2 regulating cell proliferation. These results suggest that SNAI1 promotes fibrosis and cell proliferation in human corneal endothelium through ZEB1 and CDK2.

LncRNA TRERNA1 Function as an Enhancer of SNAI1 Promotes Gastric Cancer Metastasis by Regulating Epithelial-Mesenchymal Transition

Long noncoding RNA (lncRNA) has been implicated in cancer, but little is known about the role of lncRNAs as regulators of tumor metastasis. In the present study, we demonstrate that lncRNA TRERNA1 acts like an enhancer of SNAI1 to promote cell invasion and migration and to contribute to metastasis of gastric cancer (GC). TRERNA1 is significantly unregulated in GCs and GC cell lines. Increased TRERNA1 is positively correlated with lymph node metastasis of GCs. RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assays revealed that TRERNA1 functions as a scaffold to recruit EZH2 to epigenetically silence epithelial-mesenchymal transition marker CDH1 by H3K27me3 of its promoter region. TRERNA1 knockdown markedly reduced GC cell migration, invasion, tumorigenicity, and metastasis. Depletion of TRERNA1 reduced cell metastasis of GCs in vivo. Taken together, our findings indicated that TRERNA1 serves as a critical effector in GC progression by regulating CDH1 at the transcription level. It is implied that TRERNA1/CDH1 is a new potential target for GC therapy.

Mithramycin inhibits epithelial-to-mesenchymal transition and invasion by downregulating SP1 and SNAI1 in salivary adenoid cystic carcinoma

Mithramycin exhibits certain anticancer effects in glioma, metastatic cerebral carcinoma, malignant lymphoma, chorionic carcinoma and breast cancer. However, its effects on salivary adenoid cystic carcinoma remain unclear. Here, we report that mithramycin significantly inhibited epithelial-to-mesenchymal transition and invasion in human salivary adenoid cystic carcinoma cell lines. The underlying mechanism for this activity was further demonstrated to involve decreasing the expression of the transcription factors specificity protein 1 and SNAI1. Specificity protein 1 is a pro-tumourigenic transcription factor that is overexpressed in SACC-LM and SACC-83 cells, and its expression is inhibited by mithramycin. Moreover, chromatin immunoprecipitation assays showed that specificity protein 1 induced SNAI1 transcription through direct binding to the SNAI1 promoter. In summary, this study uncovered the mechanism through which mithramycin inhibits epithelial-to-mesenchymal transition and invasion in salivary adenoid cystic carcinoma cell lines, namely, via downregulating specificity protein 1 and SNAI1 expression, which suggests mithramycin may be a promising therapeutic option for salivary adenoid cystic carcinoma.

MicroRNA-153-3p suppress cell proliferation and invasion by targeting SNAI1 in melanoma

Malignant melanoma is one of the most common malignancies of the skin cancer and increasing evidences revealed that microRNAs (miRNAs) exert significant effects in melanoma. In the present study, the underlying function of microRNA-153-3p (miR-153-3p) in melanoma was investigated from different levels, including cell level, protein level and gene level. Our results showed that expression of miR-153-3p was lower in melanoma tissues and melanoma cells compared with the para-tumor tissue and normal melanocytes. The overexpression of miR-153-3p inhibited the cell proliferation and invasion, at the same time promoted cell apoptosis. Moreover, we identified that snail family transcriptional repressor 1 (SNAI1) is the direct target of miR-153-3p, and there is a negative correlation between miR-153-3p level and SNAI1 expression. In summary, we presented the evidences that miR-153-3p may act as a tumor suppressor by down-regulating the expression of SNAI1 in melanoma and miR-153-3p might be a potential biomarker in the diagnosis and treatment of malignant melanoma.

The immune checkpoint ligand PD-L1 is upregulated in EMT-activated human breast cancer cells by a mechanism involving ZEB-1 and miR-200

PD-L1 expression and regulation by mesenchymal tumor cells remain largely undefined. Here, we report that among different EMT-activated MCF7 human breast cancer cell clones, PD-L1 was differentially upregulated in MCF7 sh-WISP2, MCF7-1001/2101, and MDA-MB-231 cells but not in MCF7 SNAI1 and MCF7 SNAI1-6SA cells. Mechanistic investigations revealed that siRNA silencing of ZEB-1, but not SNAI1, TWIST, or SLUG and overexpression of miR200 family members in MCF7 sh-WISP2 cells strongly decreased PD-L1 expression. Thus, we propose that PD-L1 expression in EMT-activated breast cancer cells depends on the EMT-TF involved in EMT activation. Interestingly, siRNA-mediated targeting of PD-L1 or antibody-mediated PD-L1 block restored the susceptibility of highly resistant MCF7 sh-WISP2 and MCF7-2101 cells to CTL-mediated killing. Additionally, these results provide a novel preclinical rationale to explore EMT inhibitors as adjuvants to boost immunotherapeutic responses in subgroups of patients in whom malignant progression is driven by different EMT-TFs.

MicroRNA-153 inhibits tumor progression in esophageal squamous cell carcinoma by targeting SNAI1

One of the important mediators of Epithelial to mesenchymal transition (EMT) is the Snail1 protein (encoded by SNAI1) which facilitates transition to mesenchymal state by transcriptionally repressing the epithelial cell marker E-cadherin. Given its central role in EMT and tumor metastasis, the cell has evolved multiple levels of regulatory mechanism at transcriptional, post-transcriptional, and post-translational level to regulate SNAI1 expression. Recently, miR-153 has been shown to regulate SNAI1 expression in hepatocellular carcinoma. The objective of the current study was to determine if SNAI1 expression in esophageal squamous cell carcinoma (ESCC) is regulated by miR-153. Metagenomic analysis of The Cancer Genome Atlas (TCGA) data identified an inverse correlation between miR-153 and SNAI1 expression in ESCC. Our study showed that the expression of miR-153 was noticeably downregulated in the ESCC cell line investigated and tissues, compared with normal esophageal epithelial cells and matched adjacent non-tumorous esophageal tissue. We demonstrated that miR-153 downregulated Snail expression by directly targeting the 3'-untranslated region (3'UTR) of SNAI1, which could be rescued by the use of miR-153 mimic and antagomir in ESCC cell line and normal esophageal epithelial cells, respectively. MiR-153 mimic inhibited the migration and invasion ability of ESCC cells whereas miR-153 antagomir promoted migration and invasion of normal esophageal epithelial cell line. Finally, overexpression of miR-153 in the ESCC cell line significantly attenuated experimental lung metastasis as assessed by tail vein injection in xenograft assay. Cumulatively, our data indicate that suppression of miR-153 dictates SNAI1 upregulation during EMT and metastatic progression of ESCC.

SNAI1 promotes the development of HCC through the enhancement of proliferation and inhibition of apoptosis

SNAI1, a zinc‐finger transcription factor, plays an important role in the induction of epithelial–mesenchymal transition (EMT) in various cancers. However, the possible functions of SNAI1 in the proliferation and apoptosis of hepatocellular carcinoma have not been clearly identified. In this study, we investigated the effects and mechanisms of SNAI1 in the proliferation and apoptosis of hepatocellular carcinoma using clinical samples and cell lines. We found that SNAI1 is highly expressed in the tissues of liver cancer compared with adjacent nontumor tissues. SNAI1 is also highly expressed in the hepatoma cell lines HepG2, SMMC‐7721, and BEL‐7402 compared with the human normal liver cell line L02. We also observed that SNAI1 expression was correlated with distal metastasis, incomplete tumor capsule formation, and histological differentiation in hepatocellular carcinoma (HCC). Moreover, we demonstrated that knockdown of SNAI1 via lentiviral vectors of RNAi against SNAI inhibited cell proliferation by inducing G1 arrest, which was accompanied by the downregulation of cyclin D1 but not that of cyclin A. In addition, knockdown of SNAI1 promoted apoptosis by decreasing the expression of Bcl‐2. In conclusion, our findings revealed that SNAI1 is involved in the development of hepatocellular carcinoma via regulating the growth and apoptosis of tumor cells.

Emerging Transcriptional Mechanisms in the Regulation of Epithelial to Mesenchymal Transition and Cellular Plasticity in the Kidney

Notwithstanding controversies over the role of epithelial to mesenchymal transition in the pathogenesis of renal disease, the last decade has witnessed a revolution in our understanding of the regulation of renal cell plasticity. Significant parallels undoubtedly exist between ontogenic processes and the initiation and propagation of damage in the diseased kidney as evidenced by the reactivation of developmental programmes of gene expression, in particular with respect to TGFβ superfamily signaling. Indeed, multiple signaling pathways converge on a complex transcriptional regulatory nexus that additionally involves epigenetic activator and repressor mechanisms and microRNA regulatory networks that control renal cell plasticity. It is becoming increasingly apparent that differentiated cells can acquire an undifferentiated state akin to “stemness” which is leading us towards new models of complex cell behaviors and interactions. Here we discuss the latest findings that delineate new and novel interactions between this transcriptional regulatory network and highlight a hitherto poorly recognized role for the Polycomb Repressive Complex (PRC2) in the regulation of renal cell plasticity. A comprehensive understanding of how external stimuli interact with the epigenetic control of gene expression, in normal and diseased contexts, establishes a new therapeutic paradigm to promote the resolution of renal injury and regression of fibrosis.

Paradoxical E-cadherin increase in 5FU-resistant colon cancer is unaffected during mesenchymal-epithelial reversion induced by γ-secretase inhibition

AIM

Presenilin-1 (PS1), the main component of γ-secretase activity support a key role during Epithelial-Mesenchymal Transition (EMT) and chemoresistance acquisition by triggering a complex sequence of molecular events, including E-cadherin down-regulation. However, we hypothesize that EMT and chemoresistance should be deemed separate processes in HCT-8 colon cancer cells.

MAIN METHODS

HCT-8 and HCT-8FUres invasion was evaluated by trans-well assay. uPA activity was detected by zymography. Prostaglandin E2 levels were quantified using an ELISA kit. E-cadherin FL and CTF2, PS1, Notch1, Cyclin D1, COX2, SNAI1 and α-SMA expression were determined using Western blot technique. β-Catenin localization was observed by confocal microscopy. Cell apoptosis was evaluated by cytofluorimetric assay, and measurement of caspase-3 and cl-PARP. γ-Secretase activity was inhibited by DAPT, a γ-secretase inhibitor.

KEY FINDINGS

Chemoresistant HCT-8 underwent EMT that can be efficiently reversed by inhibiting PS1 activity, leading thus to a normalization of mostly of the pivotal features showed by the invasive cancer phenotype. Indeed, we observed decreased SNAI1 and Notch 1 activation, altogether with reduced E-cadherin cleavage. Concomitantly, resistant HCT-8 invasiveness was almost completely abolished. However, such reversion was not followed by any increase in apoptotic rate, not by changes in E-cadherin levels. Indeed, despite HCT-8FUres underwent an undeniable EMT, full-length E-cadherin levels were found remarkably higher than those observed in wild HCT-8.

SIGNIFICANCE

High E-cadherin concentration in presence of enhanced γ-secretase activity is incontestably a paradoxically result, highlighting that E-cadherin loss is not a pre-requisite for EMT. Additionally, EMT and chemoresistance acquisition in HCT-8 should be considered as distinct processes.

MicroRNA-153 acts as a prognostic marker in gastric cancer and its role in cell migration and invasion

MicroRNA (miRNA)-153 (miR-153) has been considered as a novel tumor-related miRNA and is found to be significantly deregulated in human cancers. In this study, we found that the expression levels of miR-153 were obviously lower in gastric cancer tissues than those in matched adjacent nontumor tissues. Otherwise, miR-153 was expressed at significantly lower levels in aggressive tumor tissues. Clinical association analysis indicated that low expression of miR-153 was prominently correlated with poor prognostic features in gastric cancer. Furthermore, we demonstrated that the low expression of miR-153 was correlated with short 5-year survival of gastric cancer patients. Multivariate Cox regression analysis indicated that miR-153 was an independent prognostic marker in gastric cancer. Our in vitro studies showed that upregulation of miR-153 reduced cell migration and invasion in MKN-45 cells. Meanwhile, downregulation of miR-153 promoted SGC-7901 cell migration and invasion. An inverse correlation between miR-153 and SNAI1 expression was observed in gastric cancer tissues. In addition, upregulation of miR-153 reduced SNAI1 expression and subsequently suppressed epithelial–mesenchymal transition (EMT) with elevated expression of E-cadherin and reduced expression of vimentin in MKN-45 cells. Furthermore, downregulation of miR-153 increased SNAI1 expression and promoted EMT in SGC-7901 cells. In conclusion, miR-153 is an independent prognostic marker for predicting survival of gastric cancer patients and may promote gastric cancer cell migration and invasion, by inhibiting SNAI1-induced EMT.

Effects of microRNA-30a on migration, invasion and prognosis of hepatocellular carcinoma

The role of microRNA-30a (miR-30a) deregulation in tumor progression and its downstream signaling pathways remain unknown. Here we confirmed significant downregulation of miR-30a in hepatocellular carcinoma (HCC) tissues and cell lines compared with non-tumor counterparts. MiR-30a downregulation was significantly associated with worse disease-free survival (DFS) of HCC patients. Gain- and loss-of-function studies revealed that downregulation of miR-30a facilitated tumor cell migration, invasion and epithelial-mesenchymal transition (EMT). We identified SNAI1 as a direct target of miR-30a and demonstrated miR-30a as a novel regulator of EMT by targeting SNAI1, indicating its potential therapeutic value for reducing invasion and metastasis of HCC.

The nuclear protein expression levels of SNAI1 and ZEB1 are involved in the progression and lymph node metastasis of cervical cancer via the epithelial-mesenchymal transition pathway

Growing evidence illustrates that aberrant activation of the epithelial-mesenchymal transition plays a key role in tumor cell invasion and metastasis. Transcription factors SNAI1 and ZEB1 regulate the epithelial-mesenchymal transition. To determine if SNAI1 and ZEB1 are involved in the metastasis of cervical cancer, we used immunohistochemistry to evaluate the expression of SNAI1, ZEB1, and vimentin in tumor and stromal compartments for a large set of cervical carcinoma samples. Results were evaluated using an H score (percentage × intensity). Of 70 samples, 64 cases (91.43%) were positive for SNAI1 expression. The median SNAI1 H score was 174.00 (range, 5-285). Sixty-seven cases (95.71%) were positive for ZEB1, with a median H score of 165.77 (range, 5-260). Nuclear expression of SNAI1 and ZEB1 in tumor cells was positively associated with International Federation of Gynecology and Obstetrics (FIGO) stages (P = .015 and P = .008, respectively) and lymph node metastasis (P = .007 and P = .007, respectively); meanwhile, expression of vimentin in tumor cells was positively associated with lymph node metastasis (P = .019). According to negative vimentin expression, nuclear expression of ZEB1 in tumor cells was positively associated with FIGO stages (P = .04). According to positive vimentin expression, nuclear expression of SNAI1 in tumor cells was positively associated with FIGO stages (P = .018) and pN (P = .029). In light of these findings, we propose that SNAI1 and ZEB1 have the potential to be used as a novel predictor of pelvic lymph node metastasis and represent promising therapeutic targets in patients with cervical cancer.