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The prognosis of patients with human papillomavirus (HPV)‑negative cervical cancer is significantly worse than that of patients with HPV‑positive cervical cancer. Understanding the mechanisms of this is crucial for preventing disease evolution. In the present study, the GV367‑snail family transcriptional repressor 2 (SNAI2) lentiviral vector was constructed and transduced into C‑33A cells. Subsequently, the proliferation of tumor cells was detected using the Cell Counting Kit (CCK)‑8 method. Flow cytometry was used to analyze the cell cycle progression of tumor cells. The glucose consumption of tumor cells was detected using an oxidase assay, and the senescence of tumor cells was detected using beta‑galactosidase staining. The gene expression and the activity of p38 and ERK1/2 were detected using reverse transcription‑quantitative PCR and western blotting, respectively. The C‑33A‑SNAI2 cell line was successfully established. Compared with HeLa and C‑33A‑Wild cells, the proliferation and percentage of G0/G1‑phase cells in the C‑33A‑SNAI2 group were decreased, as detected by the CCK‑8 assay (100±0 vs. 239.1±58.3 vs. 39.7±20.1, P<0.01) and flow cytometry (34.0±7.1% vs. 46.2±10.6% vs. 61.3±5.3%, P<0.05). Compared with the HeLa group, the glucose consumption of the C‑33A‑Wild and C‑33A‑SNAI2 groups was significantly decreased (P<0.01). The results of beta‑galactosidase staining showed that the proportion of beta‑galactosidase‑positive cells in the C‑33A‑SNAI2 group was significantly decreased compared with the C‑33A‑Wild group (P<0.01). Upregulation of SNAI2 enhanced the increase in p21 expression, and the decrease in CDK1, urokinase plasminogen activator receptor (u‑PAR) and cyclin D1 expression in C‑33A cells compared with C‑33A‑Wild cells (P<0.05). In addition, the activities of p38, ERK1/2 and the phosphorylated (p)‑ERK1/2/p‑p38 ratio were decreased in the C‑33A‑SNAI2 group compared with the C‑33A‑Wild and HeLa groups (P<0.05). In conclusion, SNAI2 enhanced HPV‑negative cervical cancer C‑33A cell dormancy, which was characterized by G0/G1 arrest, by the downregulation of u‑PAR expression, and a decrease in the activity of the p‑ERK1/2 and p‑p38MAPK signaling pathways in vitro . Cancer recurrence and metastases are responsible for most cancer‑related deaths. Given that SNAI2 is required for enhancing HPV‑negative cervical cancer cell dormancy, regulating this process may promote cervical tumor cells to enter a continuous dormant state, which could be a potential approach for tumor therapy.

Regulator of ribosome synthesis 1 (RRS1) is a key factor in ribosome biosynthesis and other cellular functions. High level of RRS1 in breast cancer cell lines is associated with increased cell proliferation, invasion and migration. RRS1 controls the assembly of the 60s subunit and maturation of 25S rRNA during ribosome biosynthesis. In this study, lentiviral transfection of sh‑RNA was used to knock down the level of RRS1, to detect the effect of RRS1 on cell function and to explore the specific mechanism of RRS1 affecting cell invasion and metastasis by COIP and dual‑luciferase reporter gene assays. The present study found that RRS1 knockdown reduced the accumulation of ribosome protein L11 (RPL11) in the nucleolus, which then migrated to the nucleoplasm and bound to c‑Myc. This inhibited trans‑activation of SNAIL by c‑Myc and eventually decreased the invasion and metastasis capacity of the human breast cancer cell line BT549. Taken together, RRS1 regulates invasion and metastasis of human breast cancer cells through the RPL11‑c‑Myc‑SNAIL axis. The findings are of great significance for exploring the mechanism of breast cancer invasion and metastasis and the corresponding regulatory factors.

Understanding the mechanisms underlying malignancy in myeloma cells is important for targeted treatment and drug development. Histone deacetylases (HDACs) can regulate the progression of various cancer types; however, their roles in myeloma are not well known. In the present study, the expression of class I HDACs in myeloma cells and tissues was evaluated. Furthermore, the effects of HDAC1 on the migration of myeloma cells and the associated mechanisms were investigated. Among the class I HDACs evaluated, HDAC1 was upregulated in both myeloma cells and tissues. Targeted inhibition of HDAC1 suppressed the migration of myeloma cells. Of the assessed transcription factors, small interfering (si)‑HDAC1 decreased the expression of Slug. Overexpression of Slug reversed the si‑HDAC1‑mediated suppressed migration of myeloma cells. Mechanistically, the results revealed that HDAC1 regulated the mRNA stability of Slug, while it had no effect on its transcription or nuclear export. Furthermore, HDAC1 negatively regulated the expression of long non‑coding RNA (lncRNA) NONHSAT113026, which could bind with the 3'‑untranslated region of Slug mRNA to facilitate its degradation. The present study demonstrated that HDAC1 promoted the migration of human myeloma cells via regulation of lncRNA/Slug signaling.

It is estimated that one‑half of patients with non‑small cell lung cancer (NSCLC) undergo radiotherapy worldwide. However, the outcome of radiotherapy alone is not always satisfactory. The aim of the present study was to evaluate the effects of radiotherapy on the malignancy of NSCLC cells. It was demonstrated that radiation therapy could increase the migration and invasion of NSCLC cells in vitro. Moreover, the upregulation of visfatin, a 52‑kDa adipokine, mediated radiation‑induced cell motility. A neutralizing antibody specific for visfatin blocked radiation‑induced cell migration. Radiation and visfatin induced the expression of Snail, a key molecule that regulates epithelial to mesenchymal transition in NSCLC cells. Furthermore, visfatin positively regulated the mRNA stability of Snail in NSCLC cells, but had no effect on its protein degradation. This may be explained by visfatin‑mediated downregulation of microRNA (miR)‑34a, which was shown to bind the 3' untranslated region of Snail mRNA to promote its decay. Collectively, these findings suggested that radiation could induce cell motility in NSCLC cells through visfatin/Snail signaling.

The biological functions of circular RNAs in liver tumorigenesis have been well demonstrated by a number of studies. Nevertheless, to the best of our knowledge, the role and mechanism of action of hsa&#95;circ&#95;0008537 (circ&#95;0008537) in liver cancer pathogenesis remain undetermined. In the present study, circ&#95;0008537 expression was associated with the GLI3 gene and was markedly increased in liver cancer tissue specimens and cells. High expression levels of circ&#95;0008537 exhibited a poor prognosis. In addition, circ&#95;0008537 overexpression resulted in an increased proliferation, migration and invasion of liver cancer cells, whereas circ&#95;0008537 knockdown exhibited opposite effects. circ&#95;0008537 acted as a sponge of microRNA‑153‑3p (miR‑153‑3p), and a negative correlation was observed between circ&#95;0008537 and miR‑153‑3p expression in liver cancer. Transfection with miR‑153‑3p further abolished the effects of circ&#95;0008537 on the malignant behavior of liver cancer cells. Furthermore, circ&#95;0008537 indirectly affected the expression levels of pro‑survival protein myeloid cell leukemia 1 (MCL1) and snail family zinc finger 1 (Snail1) via miR‑153‑3p in liver cancer cells. In conclusion, the data indicated that circ&#95;0008537 facilitated liver carcinogenesis by indirectly regulating miR‑153‑3p and leading to the release of MCL1 and Snail1.

Hepatocellular carcinoma (HCC) is an aggressively malignant type of cancer with a complex pathogenesis. Multiple studies have identified that lncRNA HOXA11‑AS is involved in the development of HCC. Nevertheless, the pathological mechanisms of HOXA11‑AS in the development of HCC require further investigation. In the present study, the role and underlying mechanisms of HOXA11‑AS in HCC were examined. RT‑qPCR revealed that HOXA11‑AS expression was increased, while that of miR‑506‑3p was decreased in HCC tissues and cells compared with that in adjacent non‑tumor tissues and normal hepatic cells. Dual‑luciferase reporter assay and RNA pull‑down assay indicated that HOXA11‑AS directly interacted with miR‑506‑3p. miR‑506‑3p downregulation reversed the inhibitory effects of HOXA11‑AS deletion on cell proliferation, invasion and epithelial‑mesenchymal transition (EMT), as shown by CCK‑8 and Transwell assays, as well as western blot analysis. Bioinformatics analysis and dual‑luciferase reporter assay indicated that Slug was a target gene of miR‑506‑3p. The overexpression of Slug reversed the effects of HOXA11‑AS deletion on the viability, invasion and the EMT of HCC cells. Taken together, the present study demonstrates that HOXA11‑AS functions as an oncogene to promote the progression of HCC via the miR‑506‑3p/Slug axis, providing a therapeutic target for patients with HCC.

A common characteristic of cancer types associated with viruses is the dysregulated expression of the CDH1 gene, which encodes E‑cadherin, in general by activation of DNA methyltransferases (Dnmts). In cervical cancer, E7 protein from high risk human papillomaviruses (HPVs) has been demonstrated to interact with Dnmt1 and histone deacetylase type 1 (HDAC1). The present study proposed that E7 may regulate the expression of CDH1 through two pathways: i) Epigenetic, including DNA methylation; and ii) Epigenetic‑independent, including the induction of negative regulators of CDH1 expression, such as Snail family transcriptional repressor Snai1 and Snai2. To test this hypothesis, HPV16‑ and HPV18‑positive cell lines were used to determine the methylation pattern of the CDH1 promoter and its expression in association with its negative regulators. Different methylation frequencies were identified in the CDH1 promoter in HeLa (88.24%) compared with SiHa (17.65%) and Ca Ski (0%) cell lines. Significant differences in the expression of SNAI1 were observed between these cell lines, and an inverse association was identified between the expression levels of SNAI1 and CDH1. In addition, suppressing E7 not only increased the expression of CDH1, but notably decreased the expression of SNAI1 and modified the methylation pattern of the CDH1 promoter. These results suggested that the expression of CDH1 was dependent on the expression of SNAI1 and was inversely associated with the expression of E7. The present results indicated that E7 from HPV16/18 regulated the expression of CDH1 by the two following pathways in which Snai1 is involved: i) Hypermethylation of the CDH1 promoter region and increasing expression of SNAI1, as observed in HeLa; and ii) Hypomethylation of the CDH1 promoter region and expression of SNAI1, as observed in SiHa. Therefore, the suppression of CDH1 and expression of SNAI1 may be considered to be biomarkers of metastasis in uterine cervical cancer.

Lysyl oxidase‑like 2 (LOXL2), a member of the lysyl oxidase gene family, is involved in the progression of hepatocellular carcinoma progression and metastasis. Increased expression of LOXL2 has been identified in several types of cancer, including hepatocellular carcinoma. Recently, LOXL2 has been reported to promote epithelial‑mesenchymal transition by reducing E‑cadherin expression via the upregulation of Snail expression. The present study provided evidence demonstrating that LOXL2 inhibited the expression of fructose‑1, 6‑biphosphatase (FBP1) and enhanced the glycolysis of Huh7 and Hep3B hepatocellular carcinoma cell lines in a Snail‑dependent manner. Overexpression of the point‑mutated form of LOXL2 [LOXL2(Y689F)], which lacks enzymatic activity, does not affect the expression of Snail1 or FBP1. Notably, targeting extracellular LOXL2 of Huh7 cells with a therapeutic antibody was unable to abolish its regulation on the expression of Snail and FBP1. Knockdown of LOXL2 also interrupted the angiogenesis of Huh7 and Hep3B cells, and this effect could be rescued by the overexpression of Snail. Furthermore, upregulation of hypoxia‑inducible factor 1α (HIF‑1α) and vascular endothelial growth factor (VEGF) expression was observed in Huh7 and Hep3B cells expressing wild‑type LOXL2. Notably, the selective LOXL2 inhibitor LOXL2‑IN‑1 could upregulate the expression of FBP1 and inhibit the expression of Snail, HIF‑1α and VEGF in HCC cells, but not in FBP1‑knockdown cells. The results of the present study indicated that the intracellular activity of LOXL2 upregulated HIF‑1α/VEGF signaling pathways via the Snail‑FBP1 axis, and this phenomenon could be inhibited by LOXL2 inhibition. Collectively, these findings further support that LOXL2 exhibits an important role in the progression of hepatocellular carcinoma and implicates LOXL2 as a potential therapeutic agent for the treatment of this disease.

Zinc finger protein SNAI1 (SNAIL) and zinc finger protein SNAI2 (SLUG) transcription factors promote epithelial‑mesenchymal transition, a process through which epithelial cells acquire a mesenchymal phenotype, increasing their migratory and invasive properties. In prostate cancer (PCa) progression, increased expression levels of SNAIL and SLUG have been described. In advanced PCa, a decrease in the cell surface proteoglycan syndecan‑1 (SDC‑1), which has a role in cell‑to‑extracellular matrix adhesion, has been observed. Notably, SDC‑1 nuclear location has been observed in mesenchymal cancers. The present study aimed to determine if SNAIL and SLUG may be associated with the nuclear location of SDC‑1 in PCa. To determine the location of SDC‑1, antibodies against its intracellular domain (ID) or extracellular domain (ED) were used in benign prostatic hyperplasia (BPH) and PCa samples with high Gleason scores. Only ID‑SDC‑1 was located in the cell nuclei in advanced PCa samples, but not in the BPH samples. ED‑SDC‑1 was located in the cell membrane and cytoplasm, exhibiting decreased levels in PCa in comparison with those in BPH. Furthermore, LNCaP and PC3 PCa cell lines with ectopic SNAIL expression exhibited nuclear ID‑SDC‑1. No change was observed in the ED‑SDC‑1 levels, and maintained its location in the cell membrane and cytoplasm. SLUG induced no change in ID‑SDC‑1 location. At the protein level, an association between SNAIL and nuclear ID‑SDC‑1 was observed. In conclusion, the results of the present study demonstrated that nuclear ID‑SDC‑1 localization was associated with SNAIL expression in PCa cell lines.

Endothelial‑to‑mesenchymal transition (EndMT) serves an important role in the vascular remodeling of pulmonary arterial hypertension (PAH). However, little is known about the correlation between hydrogen sulfide (H2S), a protective gaseous mediator in PAH and the process of EndMT. Male Sprague‑Dawley rats (10 weeks old) received a single dose of monocrotaline (MCT; i.p., 60 mg/kg) and were randomly treated with NaHS [an H2S donor; intraperitoneal (i.p.) 1 mg/kg/day], DL‑propagylglycine (an inhibitor of H2S synthesis; PAG; i.p., 10 mg/kg/day) or saline, 7 days after MCT injection. Rats were sacrificed 21 days after MCT injection. A selection of human pulmonary artery endothelial cells (HPAECs) were pretreated with NaHS or saline and stimulated with transforming growth factor (TGF)‑β1 (10 ng/ml), and the other HPAECs were transfected with a cystathionine γ‑lyase (CSE, an H2S synthesizing enzyme) plasmid and subsequently stimulated with TGF‑β1. NaHS was indicated to inhibit EndMT and PAH progression by inhibiting the induction of the nuclear factor (NF)‑κB‑Snail pathway. In contrast, the depletion of H2S formation by PAG exacerbated EndMT and PAH by activating NF‑κB‑Snail molecules. In HPAECs, NaHS dose‑dependently inhibited TGF‑β1‑induced EndMT and the activation of the NF‑κB‑Snail pathway. Transfection with a CSE plasmid significantly repressed TGF‑β1‑induced expression of the mesenchymal marker and upregulated the expression of the endothelial marker, which was accompanied by the suppression of the NF‑κB‑Snail pathway. The inhibitory effect of CSE overexpression on TGF‑β1‑induced EndMT was significantly reversed by pretreatment with PAG. In conclusion, the current study provides novel information elucidating the beneficial effect of H2S on PAH through inhibiting the induction of the NF‑κB‑Snail pathway and the subsequent process of EndMT in pulmonary arteries.

Jumonji domain‑containing protein 2A (JMJD2A) has been identified to promote cell proliferation in bladder cancer; however, it remains undetermined whether JMJD2A regulates cell migration and invasion in bladder cancer. The aim of the present study was to further investigate the roles of JMJD2A in bladder cancer. The expression levels of JMJD2A in bladder cancer tissues and cell lines were established by RT‑qPCR assays and western blot analysis. Moreover, by gain‑ and loss‑of‑function assays, the effects of JMJD2A on migration and invasion as well as proliferation were investigated in bladder cancer cells. The results revealed that the expression level of JMJD2A was significantly upregulated in bladder cancer tissues and cell lines compared to adjacent non‑tumor tissues and a human immortalized bladder urothelial cell line. Kaplan‑Meier survival analysis indicated that patients with high JMJD2A expression level had shorter overall survival. Moreover, JMJD2A could promote cell migration and invasion by facilitating epithelial‑mesenchymal transition (EMT) in bladder cancer. In addition, it was determined that JMJD2A promoted EMT through regulation of SLUG expression. Collectively, our findings revealed that JMJD2A may act as an oncogene and participate in bladder cancer progression, which provides a promising therapeutic strategy for patients with bladder cancer.

Gastric cancer (GC) is the fifth most prevalent type of malignancy and the third leading cause of cancer‑related mortality worldwide, with the prognosis of patients with late‑stage GC remaining at poor levels. Long non‑coding RNA (lncRNA) H19 (H19) is involved in the growth and metastasis of tumors, and it is upregulated under hypoxic conditions and in certain types of cancer; however, the underlying mechanisms of action of this lncRNA as regards the initiation and development of GC remain unknown. Thus, in the present study, we aimed to determine the role of lncRNA H19 in GC and to elucidate the underlying mechanisms. H19 was found to be upregulated in GC tissues and cells compared with the para‑cancerous tissues, and an elevated expression of H19 was associated with lymph node metastasis and TNM stage. Furthermore, the downregulation of H19 suppressed the proliferation, invasion, migration and epithelial‑mesenchymal transition of GC cells in vitro and suppressed tumor growth in vivo. H19 was also found to be able to bind with miR‑22‑3p, and H19‑induced cell growth and metastasis were shown to be reversed by the upregulation of miR‑22‑3p; the miR‑22‑3p level was found to inversely correlate with H19 expression in GC tissues. Furthermore, the overexpression of miR‑22‑3p notably suppressed the proliferation, migration and invasion of GC cells, and these effects were enhanced by the downregulation of Snail1. In addition, cell growth and metastasis induced by miR‑22‑3p downregulation were partially reversed by the knockdown of Snail1. Furthermore, a negative correlation was observed between the mRNA expression levels of miR‑22‑3p and Snail1 in GC tissues. On the whole, the findings of the present study revealed that H19 was upregulated in GC tissues, which promoted tumor growth and metastasis via the miR‑22‑3p/Snail1 signaling pathway. In summary, these findings provide novel insight into the potential regulatory roles of H19 in GC, and suggest that the H19/miR‑22‑3p/Snail1 axis may prove to be a promising therapeutic target for the treatment of patients with GC.

The zinc finger protein Snail1 is an important factor in the regulation of the epithelial‑mesenchymal transition (EMT) of hepatocellular carcinoma (HCC) cells. The present study demonstrated that the expression of Snail1 in HCC tissues was significantly higher compared with its expression in tissues adjacent to primary sites, as determined via western blotting. Furthermore, the results of a dual luciferase assay revealed that hsa‑microRNA(miR)199a‑5p negatively regulated the protein expression of Snail1 by binding to its 3' untranslated region. However, in a comparative analysis of primary HCC and its metastatic tissues using reverse transcription‑quantitative polymerase chain reaction and western blotting, it was demonstrated that the expression of hsa‑miR199a‑5p and Snail1 in HCC metastatic tissues were significantly higher compared with primary lesions and an association between them identified that hsa‑miR199a‑5p lost its ability to negatively regulate Snail1. This result is contradictive to the fact that hsa‑miR199a‑5p inhibits the expression of the Snail1 protein. The present study hypothesized that the aberrant expression of long non‑coding RNA was the cause of hsa‑miR199a‑5p inactivation based on loss of function rather than a reduction in content. The data collected in the present study confirmed the hypothesis that AB209371 binds to hsa‑miR199a‑5p and weakened the inhibitory effect of hsa‑miR199a‑5p on Snail1 expression. In addition, an in vitro EMT model was established in the present study by inducing HCC cells with TGF‑β1. The results revealed that AB209371 silencing effectively reversed the hsa‑miR199a‑5p mediated inhibition of EMT by negatively regulating Snail1 protein expression. Therefore, AB209371 silencing in combination with hsa‑miR199a‑5p expression may serve as an effective means to inhibit EMT in HCC cells. The present study also revealed that hsa‑miR199a‑5p/Snail1 exhibits a dominant regulatory effect in the EMT of HCC cells via a Snail1 recovery experiment. In conclusion, to the best of our knowledge, the present study confirmed for the first time that the high expression of AB209371 is favorable for the EMT in HCC cells and may be a direct cause of hsa‑miR199a‑5p inactivation (an HCC metastasis suppressor). Additionally, AB209371 silencing combined with hsa‑miR199a‑5p overexpression may be an effective means to inhibit the metastasis of HCC and the EMT of HCC cells.

RNA‑binding proteins (RBPs) play a fundamental role in the recurrence and metastasis of colorectal cancer (CRC). In this study, we identified muscleblind‑like 1 (MBNL1), an RBP implicated in developmental control, as a robust suppressor of CRC cell metastasis in vitro. By using a scratch assay coupled with time‑lapse live cell imaging, our findings revealed that the knockdown of MBNL1 induced epithelial‑to‑mesenchymal transition (EMT)‑like morphological changes in the HCT‑116 cells, accompanied by an enhanced cell motility, and by the downregulation of E‑cadherin and the upregulation of Snail expression. By contrast, the ectopic overexpression of MBNL1 suppressed EMT, characterized by the upregulation of E‑cadherin and the downregulation of Snail expression. Mechanistically, Snail rather than E‑cadherin, was identified as a direct downstream target gene of MBNL1. The ectopic the overexpression of MBNL1 markedly enhanced the recruitment of Snail transcripts to processing bodies (P‑bodies), leading to the increased degradation of Snail mRNA and consequent translational silencing. Furthermore, the effect of MBNL1 on CRC cell migration was confirmed in additional CRC cell lines. SW480 and HT‑29 cells exhibited similar changes in migratory capacity and the expression of Snail/E‑cadherin to those observed in HCT‑116 cells. On the whole, this study demonstrates that MBNL1 destabilizes Snail transcripts and, in turn, suppresses the EMT of CRC cells through the Snail/E‑cadherin axis in vitro. Therefore, this EMT‑related MBNL1/Snail/E‑cadherin axis may prove to be a novel therapeutic target for CRC metastasis.

SET domain bifurcated 1 (SETDB1) is a histone H3 lysine 9 methyltransferase that is highly expressed in various tumor types, including breast cancer. However, how SETDB1 functions in breast cancer is unclear. In the present study, proliferation, migration and invasion assays were performed to explore the role of SETDB1 in breast cancer cells. SETDB1 downregulation in BT549 and MDA‑MB‑231 cells reduced cell proliferation, whereas upregulation in MCF7 and T47D cells enhanced proliferation. Depletion of SETDB1 suppressed cell migration and invasion in vitro and reduced lung metastasis in vivo. By contrast, SETDB1 overexpression enhanced cell migration and invasiveness. Notably, SETDB1 overexpression appeared to induce epithelial‑mesenchymal transition (EMT) in MCF7 cells. Mechanistic investigations indicated that SETDB1 acts as an EMT inducer by binding directly to the promoter of the transcription factor Snail. Thus, SETDB1 is involved in breast cancer metastasis and may be a therapeutic target for treating patients with breast cancer.

The Snail family transcriptional repressor 1 gene (Snail1) was screened in multiple myeloma cells (MMCs) from bortezomib-resistant MM patients and was found to be significantly associated with the development of drug-resistance mechanisms. In the present study, we first confirmed that the protein expression of Snail1 in bortezomib-resistant MMCs was significantly higher than that in MMCs without bortezomib resistance. The mechanistic studies confirmed that the enhancement of Snail1 expression in bortezomib-resistant MMCs directly upregulated transcription of the intracellular MDR1 gene to immediately develop multiple drug resistance mechanisms and inhibited P53 protein expression through the Snail1/hsa-miRNA-22-3p/P53 pathway to inhibit tumor cell apoptosis. By upregulating MDR1 and downregulating P53, Snail1 induced the drug resistance of MMCs to bortezomib, while Snail1 gene silencing effectively improved the drug sensitivity of MMCs to bortezomib chemotherapy. The present study further elucidated the drug resistance mechanisms of MMCs and provides evidence for increased clinical efficacy of bortezomib in MM patients.

Extensive evidence suggests that the genetic etiologies of breast cancer (BC) and ovarian cancer (OC) show a certain degree of similarity. This study aimed to find out whether the single nucleotide polymorphisms (SNPs) of genes SNAI1 and TWIST1 may affect BC and OC susceptibility. A total of 7 tagging‑SNPs (tSNPs) were directly genotyped in 1,161 BC cases, 286 OC cases and 1,273 cancer‑free controls among Chinese Han women. Twenty‑eight variants in these 2 genes were genotyped by 'in silico' genotype imputation. Logistic regression (LR) revealed that tSNPs SNAI1 rs6125849, TWIST1 rs4721746 and TWIST1 rs4721745 were protective genetic variants for BC/OC. Allelic association tests of gene‑wide SNPs demonstrated that the minor alleles of SNAI1 rs6125849, TWIST1 rs4721745 and TWIST1 rs11973396 were strongly associated with BC/OC susceptibility. Multivariate LR presented that SNAI1 rs6125849, TWIST1 rs4721745, rs4721746 and rs11973396 affected BC/OC susceptibility independently, and women harboring all four protective genoytpes had the lowest risk. Multifactor dimensionality reduction analysis further showed that SNAI1 rs6125849 and TWIST1 rs4721745 had the strongest synergistic interaction. Functional annotation predicted that the minor alleles of SNAI1 rs6125849 and TWIST1 rs4721745 altered their binding affinities with transcription factors E2F6 and TCF11‑MafG respectively. These results indicate that genetic variants in SNAI1 and TWIST1, most probably SNAI1 rs6125849 and TWIST1 rs4721745, may modulate BC and OC susceptibility.

Epsin 3 (EPN3) expression is limited to gastric parietal cells and wounded or pathological tissue rather than normal brain tissue, and although it has been identified as an oncogene in estrogen receptor‑positive breast cancer and non‑small cell lung cancer, its function in cancer is poorly understood. The present study aimed to investigate the association of EPN3 expression with the clinicopathological features of patients with glioma, as well as the effects of EPN3 on glioblastoma cells and the potential molecular mechanisms for its effects on glioblastoma cell behavior. EPN3 expression was assessed by immunohistochemistry in tissue samples from 167 patients with glioma, as well as by western blotting in 5 glioblastoma cell lines. The U87 and U251 glioblastoma cell lines were used to investigate the effects of EPN3 on glioblastoma cell invasion and migration through gain and loss of EPN3 expression experiments; expression levels were further investigated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analyses. The results demonstrated that EPN3 expression levels were upregulated in high‑grade glioma tissues compared with low‑grade tissues, and there were varying expression levels of EPN3 in the five glioblastoma cell lines. No significant differences were observed in EPN3 expression in relation to patient age, sex or tumor size. Overexpression of EPN3 promoted glioblastoma cell migration and invasion, which we hypothesized was through affecting epithelial‑mesenchymal transition (EMT). RT‑qPCR and western blotting revealed that EPN3 upregulation increased the expression of Notch1 intracellular domain, β‑catenin, Slug, Twist and zinc‑finger E‑box‑binding homeobox (ZEB)‑1. These results suggested that EPN3 enhances the migration and invasion of glioblastoma cells by activating the transcription factors Slug, Twist and ZEB1, but not Snail 1 or ZEB2, to induce EMT in glioma cells; EPN3 involvement in the Notch and WNT/β‑catenin signaling pathways may contribute to this process.

Fibroblast growth factor 18 (FGF18) increases cell motility and invasion in colon tumors, and is linked with ovarian and lung tumors. Furthermore, the increased expression of FGF18 mRNA and protein has been associated with poor overall survival in cancer patients. However, its function has not been investigated in breast cancer. In the present study, we demonstrated that FGF18 promoted cell growth and metastasis in vitro and stimulated tumor growth in xenograft models in vivo. FGF18 mediated the proliferation of MDA‑MB‑231 cells via the ERK/c‑Myc signaling pathway and induced epithelial‑to‑mesenchymal transition (EMT) factors to promote cancer migration and invasion. The decreased expression of FGF18 was strongly correlated with the loss/reduction of p‑ERK, c‑Myc, N‑cadherin, vimentin and Snail 1 protein in MDA‑MB‑231 cells. Collectively, our results indicated that FGF18 played an important role in the growth and metastasis of breast cancer via the ERK/c‑Myc signaling pathway and EMT, indicating that FGF18 may be a potential molecular treatment target for breast cancer.

Dormant tumor cells (DTCs) serve a crucial role in the pathogenesis of metastasis and may compromise the efficacy of existing therapeutic modalities aimed at fully eradicating cancer. However, the mechanisms underlying the dormant-to-proliferating switch of DTCs remain largely unknown. The lung is one of the most common sites of metastatic recurrence. The transdifferentiation of alveolar epithelial cells II (AEC IIs) to AEC Is is a hallmark of alveolar epithelial stimulation. However, the role of AEC II transdifferentiation during the reactivation of DTCs has not been fully elucidated. In the present study, we found that tumor cells promoted the transdifferentiation of AEC IIs. Furthermore, the supernatant of the transdifferentiation of AEC IIs to AEC Is (Super-TDA) promoted the dormant-to-proliferating switch of DTCs via the autocrine effect of TGF-β1 on the 3D BME culture system in vitro. Monensin and LY2109761 blocked the dormant-to-proliferating switch of DTCs induced by Super-TDA. Although lipopolysaccharide did not directly stimulate the reactivation of DTCs, it promoted DTC reactivation by increasing the secretion of TGF-β1 in the Super-TDA. We further demonstrated that the upregulation of SNAI2 expression was required for Super-TDA facilitating the DTC dormant-to‑proliferating switch. Taken together, our findings demonstrated that tumor cells may promote AEC II transdifferentiation. Furthermore, the transdifferentiation of AEC IIs may, in turn, induce the reactivation of 3D-established DTCs by promoting TGF-β1/SNAI2 signaling. Targeting this process may provide novel therapeutic strategies for the inhibition of the dormant‑to-proliferating switch.

Tongue squamous cell carcinoma (TSCC) is more aggressive than other cancers in the head and neck region because of its potential for metastasis. Recently, β2‑adrenergic receptor (β2‑AR) has been reported to be a potential promoter in various types of solid cancer. However, the role of β2‑AR and its effect on TSCC is not well documented. Histological staining, western blot analysis, migration and invasion assay were used. In this study, the expression of β2‑AR was increased in TSCC tissue compared with adjacent non‑cancerous epithelium. Further analysis demonstrated that increased expression of β2‑AR was correlated with differentiation, lymph node metastasis and reduced overall survival rate in patients with TSCC. In vitro studies confirmed that activation of β2‑AR can promote epithelial mesenchymal transition in TSCC by initiating an interleukin‑6/Stat3/Snail1 pathway. These results suggest that β2‑AR has an oncogenic role in TSCC and may be a potential therapeutic target in TSCC.

Adenosine 5'-triphosphate (ATP) is one of the most abundant biochemical constituents within the tumor microenvironment and is postulated to play critical roles in the progression of a number of types of tumors via interaction with the P2Y2 receptor. In the present study, we demonstrated that the P2Y2 receptor was highly expressed in MCF7 and Hs578T breast cancer cells. Downregulation of the P2Y2 receptor by small interfering RNA (siRNA) significantly attenuated ATP- or UTP-driven migration and invasion of the breast cancer cells as well as expression of EMT-related genes Snail and E-cadherin. Consistent with the observations in vitro, the P2Y2 receptor was found to be abundantly expressed at the invasive edge of the tumor, in infiltrating tumor cells in breast adipose tissues and/or the cancer embolus in the lymphatic sinuses compared with the tumor core areas. Furthermore, high Snail expression and weak or negative expression of E-cadherin were observed at the invasive edge of tumors. Taken together, these data indicate that the P2Y2 receptor promoted cell migration and invasion in breast cancer cells via EMT-related genes Snail and E-cadherin.

Corneal diseases exhibit a high prevalence and are prone to cause blindness; furthermore, maintaining the morphology and ionic transporter expression in corneal endothelial cells (CECs) is crucial for treatment of these diseases. This study aimed to investigate the effects of the novel Rho associated coiled-coil containing protein kinase (ROCK) inhibitor, thiazovivin (2,4‑disubstituted thiazole, TZV), on human corneal endothelial‑to‑mesenchymal transition/epithelial‑to‑mesenchymal transition (EndMT/EMT), cell morphology, junction proteins and ionic transporter expression in human CECs (HCECs) in vitro and then to clarify the mechanisms of action of TZV. In the present study, primary HCECs were cultured in vitro and passaged. The expression levels of adhesion proteins (E‑cadherin and N‑cadherin), the EndMT/EMT marker, α smooth muscle  actin (α‑SMA), the tight junction protein, Zonula occludens-1 (ZO‑1), and the ionic transporter, Na+/K+‑ATPase, were detected by immunofluorescence. The proliferative ability of the HCECs was determined by CCK-8 assay. The mRNA expression of the EndMT/EMT‑inducing gene, Snail, was examined by RT‑PCR. The protein expression levels of ROCK1/2 were evaluated by western blot analysis. The HCECs were cultured with TZV at various concentrations (2, 4, or 6 µM) for different periods of time (24 or 48 h). We found that the the cell states of the HCECs co‑cultured with 4 µM TZV for 48 h reached the optimum, and corneal EndMT/EMT was inhibited, as evidenced by the significantly upregulated expression of ZO‑1 and E‑cadherin, and the markedly downregulated expression of N‑cadherin and α‑SMA. Furthermore, the cells exhibited a normal, tightly connected hexagonal or pentagonal morphology. Additionally, the protein expression of ROCK1/2 and the mRNA expression of Snail were significantly decreased. However, there was no significant difference between the TZV‑treated and the control groups as regards HCEC proliferative ability. These findings suggested that the ROCK inhibitor, TZV (4 µM), was effective in improving the morphology, cell junctions and ionic transporter expression of HCECs by inhibiting EndMT/EMT, but had no effect on HCEC proliferation.

Epithelial-mesenchymal transition (EMT) is known to be associated with cancer progression, metastatic spread, and therapeutic resistance and to occur at the invasive front. Cancer stem cells (CSCs) display stemness features and might be implicated in tumor initiation, local recurrence and metastasis. The present study was conducted to examine the expression status and relationships between EMT- and CSC-related proteins in the different tumor areas of primary colorectal cancer (CRC), along with their clinicopathological significance. We performed immunohistochemical staining for 4 EMT-related proteins, namely E-cadherin, β-catenin, snail and vimentin, and two CSC-related proteins, namely CD44 and CD133, in two different tumor areas (the representative tumor center and the deepest invasive front) in 286 cases of primary CRC using tissue microarrays. Altered expression of all EMT-related proteins was more frequently observed in the invasive front than in the tumor center. Altered expression of E-cadherin, β-catenin and vimentin significantly associated with aggressive tumor characteristics. In particular, loss of E-cadherin expression in the invasive front significantly associated with shorter disease-free survival (DFS, P=0.002) and overall survival (OS, P=0.007). Overexpression of vimentin in the invasive front significantly correlated with poor OS (P=0.028). Loss of CD44 expression both in the tumor center and in the invasive front significantly associated with unfavorable clinicopathological characteristics. In the invasive front, but not in the tumor center, combination of the altered protein expression patterns of E-cadherin, β-catenin, vimentin, snail and CD133 significantly associated with aggressive clinicopathological factors and shorter DFS (P=0.003) and OS (P=0.005). The present data suggest that cancer cells expressing a combination of altered EMT- and CSC-related proteins may represent a potential biomarker for aggressive tumor behavior and may be a possible future candidate for molecular targeted treatments for CRC.

Snail, a zinc-finger transcriptional repressor of E-cadherin expression, is one of the key inducers of epithelial-mesenchymal transition (EMT) in epithelial cancer. In breast cancer, EMT has been associated with malignancies, including metastasis, cancer stem-like properties, and resistance to chemotherapy and radiotherapy. In this study, we analysed the role of Snail in the highly metastatic mesenchymal TUBO‑P2J mouse breast cancer cells, by loss of function using short hairpin RNA. Though silencing Snail did not restore the E-cadherin expression or induce morphological changes, Snail silencing significantly ablated in vitro and in vivo metastatic potentials. In addition, Snail silencing also reduced resistance to chemotherapy drugs and cancer stem-like properties, such as CD44 expression, aldehyde dehydrogenase (ALDH) activity, colony formation, and in vivo tumour formation and growth. However, radioresistance was not decreased by silencing Snail. Collectively, this study suggested that Snail is a main regulator of the maintenance of malignancy potentials and is a good target to prevent cancer metastasis and to increase chemotherapy susceptibility.

The conversion of arachidonic acid into prostaglandins by cyclooxygenase (COX)-2 contributes to the biological properties of malignant tumours. During the initiation and development of various tumours, the Notch family plays a key role. However, the association between COX‑2 and the Notch family in gastric cancer (GC) remains unclear. The present study aimed to clarify the mechanisms through which COX‑2 participates in the pathogenesis of GC. Quantitative PCR and western blot analysis were used to detect the expression of Notch family members and COX‑2 in human GC and paracancerous tissues, GES‑1 cells and GC cell lines (AGS, SGC‑7901, BGC‑823, and MGC‑803) treated with or without celecoxib, prostaglandin E2 and small interfering RNA (siRNA). A CCK‑8 assay was performed to detect the proliferation of GC cells transfected with siRNA against COX‑2 (si‑COX‑2). A high mRNA expression of Notch1 and a decreased expression of Notch-1 intracellular active domain (N1IC) in GC were found to be related to the depth of invasion and TNM staging. The mRNA levels of Notch2, Notch3, Jagged1 and N2IC were found to be high in GC. A High expression of COX‑2 was associated with poorly differentiated and deeply invasive GC. COX‑2 and Notch1 exhibited an inverse expression pattern in the GES‑1 cells and different GC cell lines; the inhibition of COX‑2 increased Notch1 expression and activated the GC cells, whereas Notch1 downregulation had the opposite effect. Notch1 exhibited varying effects on Snail in the GC cell lines. The downregulation of COX‑2 expression significantly inhibited the proliferation of GC cells. On the whole, the expression of Notch signalling molecules differed in GC. COX‑2 inversely regulated Notch1 in GC and partially depended on the Notch1 signalling pathway in altering the expression of Snail.

Hepatocellular carcinoma (HCC) is one of the common malignances in the world and is associated with high mortality and poor prognosis, partly due to early invasion and metastasis. Cx32 has been indicated to be involved in the progression of many cancers including HCC, but its relationship with tumor invasion and metastasis is still controversial. In the present study, the downregulated Cx32 in HCC tissue was found negatively correlated with histological grade and lymph node metastasis. Cx32 regulated HCC migration and invasion in vitro and inhibited tumor metastasis in xenograft models in vivo. We subsequently identified that Cx32 mediated epithelial-mesenchymal transition (EMT) by regulating Snail expression, and the enhanced Snail was due to activation of Wnt/β-catenin signaling in response to Cx32 inhibition. Finally, decreased expression of Cx32 showed strong correlation with loss/reduction of E-cadherin, higher expression of Snail, and nuclear accumulation of β-catenin in HCC tissues. Taken together, our results suggest that Cx32 inhibits HCC invasion and metastasis through Snail-mediated EMT, Cx32 and this signaling pathway molecules may offer potential targets for HCC cancer therapy.

Epithelial-mesenchymal transition (EMT) is a pivotal event in tumor progression during which cancer cells undergo dramatic changes acquiring highly invasive properties. In this study, we found that nobiletin, a polymethoxylated flavone, suppressed migration and invasion in both U87 and U251 glioma cells. Expression of epithelial markers (E-cadherin and occludin) was upregulated; mesenchymal markers (N-cadherin, fibronectin) and the transcriptional factor Slug were downregulated after nobiletin treatment. Transforming growth factor β (TGF-β) was applied to stimulate EMT and the results showed that nobiletin not only influenced basal level cell migration but also prevented TGF-β-triggered migration and EMT, with the AKT/GSK3β/β-catenin signaling pathway greatly involved. Furthermore, nobiletin remarkably diminished TGF-β-induced β-catenin nuclear translocation and the binding to the Slug promoter. It is worth noting that nobiletin almost blocked invasion in Slug-expressing U87 and U251 cells, and only exhibiting faint effect on non-Slug-expressing U343 glioma cells. Reinforced Slug expression in U343 cells by transfecting Slug plasmid was significantly attenuated by nobiletin, demonstrating the essential role of Slug in the anti-metastasis effect of nobiletin. Nobiletin repressed tumor growth in vivo and abrogated EMT in nude mice bearing U87-Luc xenografts, as demonstrated by Xenogen IVIS imaging and immunohistochemistry assay. Our findings suggested that nobiletin might have a great potential for treating glioblastoma.

Epithelial-to-mesenchymal transition (EMT) is essential for tumor invasion and metastasis. Snail has been proven to be a key regulator of EMT. Several studies have shown compelling evidence that Snail is also an important regulator of tumor growth and aggression; however, the role of Snail in the cell cycle has not been clarified. We decreased Snail expression by siRNA transfection and lentiviral‑mediated RNAi, to explore the effect of silencing Snail on the tumorigenicity and migration of lung carcinoma (lung cancer) cells. The results showed that silencing Snail conferred significant anti-proliferative activity and inhibited cell migration, tumor growth and metastasis both in vitro and in vivo. To understand the mechanism of these effects, we further investigated correlations among Snail expression, EMT and cell cycle. Significantly, Snail knockdown reversed EMT processes in lung cancer cells. Furthermore, the cyclin-dependent kinase inhibitor P21 was upregulated after silencing Snail. P21 upregulation manifested its tumor suppressor effects and arrested cells in the G2/M phase, not the G1/S phase following Snail depletion in lung cancer cells. These data suggest that silencing Snail decreases the malignant behaviors of lung cancer cells by reversing EMT processes and causing cell cycle defects.

Endometrial cancer is the most common gynecological cancer. We identified interleukin 11 (IL11) as a critical mediator of endometrial tumourigenesis and demonstrated that IL11 regulates chondroitin sulfate proteoglycan (CSPG4) in human placental trophoblasts. CSPG4 is a cell membrane protein overexpressed in numerous human cancers, although its role in endometrial cancer has not been investigated. We examined CSPG4 expression and localization in primary human type I endometrioid grade (G) 1-3 tumours by qPCR and immunohistochemistry and determined whether IL11 stimulated CSPG4. IL11 upregulated CSPG4 mRNA in HEC1A (G2-derived endometrial epithelial cancer cell line) cells. IL11 administration to BALB/c nude mice enhanced HEC1A xenograft tumour growth and increased CSPG4 protein in tumours. CSPG4 mRNA was unchanged between human G1-3 endometrial cancer and control tissues. CSPG4 protein levels were elevated in the epithelium of G2 and G3 endometrial cancer and in the tumour-associated stroma of G3 tumour tissues compared to proliferative phase or post-menopausal endometrium. CSPG4 knockdown by siRNA reduced HEC1A proliferation and migration in vitro and reduced gene expression of the key epithelial-to-mesenchymal transition (EMT) regulator SNAIL. Our data suggest that CSPG4 inhibition may impair endometrial cancer progression by reducing cancer cell proliferation, migration and potentially EMT.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) plays an important role in multiple cellular functions including metabolism and gene transcription. Our previous study showed that GAPDH expression was elevated in colon cancer and further upregulated in liver metastatic tissues, suggesting a possilbe role of GAPDH in promoting cancer metastasis. The present study was designed to investigate the underlying mechanism, using multiple experimental approaches including genetic silencing of GAPDH expression by short hairpin RNA (shRNA) and biochemcial/molecular analyses of the key events involved in glycolytic metabolism and epithelial-mesenchymal transition (EMT). We showed that silencing of GAPDH expression resulted in a significant reduction of glycolysis in colon cancer cell lines, accompanied by a decrease in cell proliferation and an apparent change in cell morphology associated with alterations in actin expression and phalloidine staining patterns. Furthermore, GAPDH suppression also caused a downregulation of gene expression involved in cancer stem-like cells and EMT. CHIP assay and co-immunoprecipitation revealed that GAPDH physically interacted with the transcriptional factor Sp1 and enhance the expression of SNAIL, a major regulator of EMT. Suppression of GAPDH expression resulted in a signficant decrease in SNAIL expression, leading to inhibition of EMT and attenuation of colon cancer cell migration in vitro and reduced metastasis in vivo. Overall, the present study suggests that GAPDH plays an important role in cancer metastasis by affecting EMT through regulation of Sp1-mediated SNAIL expression.

MicroRNA (miRNA) is a type of endogenous non‑coding RNA implicated in various cellular processes. Studies have shown that miR-124 is involved in the malignant progression of cancer, but little is known concerning its potential role in breast cancer. Therefore, the purpose of this study was to conduct a functional analysis of miR-124 in breast cancer, and to identify its target genes in this disease. To this end, we used quantitative real-time PCR to examine the expression level of miR-124 in breast cancer tissue specimens and cell lines. To study the functional significance of miR-124, we overexpressed miR-124 with miR-124 mimics and observed breast cancer cell proliferation, colony formation, migration, and invasion abilities by in vitro cell culture experiments. Target prediction algorithms and luciferase reporter gene assays were used to identify the target genes of miR-124. We also knocked down miR-124 targets using short hairpin RNA (shRNA) constructs, and observed associated breast cancer cell characteristics by in vitro cell culture experiments. We found that miR-124 expression significantly decreased in breast cancer tissues and cells compared to normal tissues and cells. In addition, cell proliferation, colony formation, migration, and invasion were decreased after overexpression of miR-124 in breast cancer cells. Furthermore, we used several algorithms to identify the snail family zinc finger 2 (SNAI2) as a potential target gene of miR-124. The protein expression level and luciferase activity of the 3'-untranslated region of SNAI2 were significantly decreased in breast cancer cells transfected with miR-124 mimics. Cell proliferation, colony formation, migration, and invasion were also decreased after knockdown of SNAI2 by shRNA. In conclusion, our data suggest that miR-124 expression is decreased in breast cancer and plays an important role as a tumor suppressor gene by targeting SNAI2. These findings may reveal novel perspectives for clinical treatments against breast cancer.

MicroRNAs (miRNAs) have emerged as important regulators in cancer that are implicated in regulation of various cellular processes. miR-382 has been proposed as a tumor suppressor by several recent studies. However, the function of miR-382 in prostate cancer remains unknown. In this study, we aimed to investigate the potential function of miR-382 in prostate cancer. We found that miR-382 was significantly decreased in prostate cancer specimens and cancer cell lines. The overexpression of miR-382 in prostate cancer cells markedly inhibited cell proliferation, migration, and invasion. In contrast, miR-382 suppression exhibited an opposite effect. Target analysis predicted that chicken ovalbumin upstream promoter transcription factor II (COUP‑TFII) was a direct target of miR-382. This prediction was experimentally confirmed by dual-luciferase reporter assay, real-time quantitative polymerase chain reaction, and western blot analysis. Our results further demonstrated that miR-382 inhibited the downstream genes of COUP‑TFII, including Snail and matrix metalloproteinase 2 (MMP2). Moreover, the restoration of COUP‑TFII expression significantly blocked the inhibitory effect of miR-382 on cell proliferation, migration, and invasion, and Snail expression. Taken together, this study suggests that miR-382 inhibits prostate cancer cell proliferation and metastasis through inhibiting COUP‑TFII, representing an important new mechanism for understanding prostate cancer pathogenesis and providing a novel therapeutic candidate target for prostate cancer therapy.

It has been reported that epithelial-mesenchymal transition (EMT) mediates multiple physiological and pathological processes. However, the occurrence and the pathogenic role of high glucose-induced EMT in retinal pigment epithelial cells (RPE cells) is unknown. The aim of this study was to examine the effects of high glucose on EMT in RPE cells. Cultured RPE cells were exposed to 25 mM D-glucose. A vector encoding the Snail gene and siRNA targeting Snail (Snail siRNA) were transfected into the cells to induce the overexpression or silencing of Snail, respectively. AKT and extracellular signal-regulated kinase (ERK) inhibitors were used to block the activation of AKT and ERK, respectively. The levels of EMT markers, fibrogenic factors, phosphorylated ERK and phosphorylated AKT were determined by western blot analysis and immunofluorescence staining. Cell migration was evaluated by wound healing assay. Our results revealed that high glucose elevated the expression of the key EMT transcriptional factor, Snail, and that of other mesenchymal makers, and promoted cell migration. Moreover, the overexpression of Snail elevated the levels of fibronectin and connective tissue growth factor (CTGF), whereas the silencing of Snail decreased the expression of fibronectin and CTGF induced by high glucose in the cells. Mechanistically, the AKT inhibitor (AKT inhibitor IV) and ERK inhibitor (U0126) significantly decreased the expression of Snail, as well as the levels of fibronectin and CTGF which were induced by high glucose. On the whole, and to the best of our knowedge, the present study is the first to demonstrate the upregulation of mesenchymal markers in RPE cells induced by high glucose, and suggest that mesenchymal transition may be involved in the pathological processes of retinal diseases.

Anaplastic thyroid cancer (ATC) is a rare malignancy that progresses extremely aggressively and often results in dismal prognosis. We investigated the efficacy of inhibiting the activated RAS/RAF/MEK pathway in ATC cells aiming to clarify the mechanism of effect and resistance. Four human ATC cell lines (ACT-1, OCUT-2, OCUT-4 and OCUT-6) were used. OCUT-4 had a BRAF mutation. OCUT-2 had both BRAF and PI3KCA mutations. ACT-1 and OCUT-6 had wild-type BRAF and NRAS mutations. The effects of dabrafenib, a selective inhibitor of the BRAFV600E kinase, and trametinib, a reversible inhibitor of MEK activity, were investigated. Dabrafenib strongly inhibited the viability in BRAF mutated cells by demonstrating G0/G1-arrest via the downregulation of MEK/ERK phosphorylation. Upregulated phosphorylation of MEK was observed in RAS mutated cells after dabrafenib treatment and caused VEGF upregulation, but was not related to the cellular proliferation. Trametinib inhibited the cellular viability to variable degrees in every cell by downregulating ERK phosphorylation. Dual blockade by both inhibitors demonstrated clear cytostatic effect in all the cells. OCUT-4 showed the weakest sensitivity to trametinib, no additional effect of either inhibitor in combination with the other, and an increase of SNAI1 mRNA expression after treatment with inhibitors, suggesting a mechanism for resistance. Our findings demonstrated the efficacy of a mutation-selective BRAF inhibitor and a MEK inhibitor in human ATC cells in a genetic alteration-specific manner.

Oxymatrine, a traditional Chinese herb extracted from Sophora flavescens Ait., displays strong anti-inflammatory and anticancer activities, but how oxymatrine exhibits anticarcinogenic effects in human colorectal cancer (CRC) remains uncertain. The present study aimed to elucidate the exact mechanism by which oxymatrine exhibits anticarcinogenic effects in CRC using the human colon cancer RKO cell line as the experimental model. CRC cells were treated with oxymatrine, and cell proliferation, migration and invasion were examined by colorimetric MTT, Transwell chamber and wound healing assays, respectively. In addition, epithelial-mesenchymal transition (EMT) markers and p65 were assessed by western blot analysis. Our study demonstrated that oxymatrine hindered the proliferation, migration and invasion of the CRC cells. Mechanistically, we found that oxymatrine modulated the expression of EMT markers including E-cadherin, Snail and N-cadherin, and reduced expression of p65 which is crucial to NF-κB activation. In conclusion, our results indicate that oxymatrine reduces the activation of the NF-κB signaling pathway and inhibits CRC invasion by modulating EMT.

Nutlin-3, a small molecule regulator of the tumor suppressor p53, targets the interaction between p53 and murine double minute 2 (MDM2) thereby promoting stabilization of p53 and subsequent p53‑dependent induction of apoptosis and cell cycle arrest. Recent studies have demonstrated that Nutlin‑3 plays a critical role in regulating tumor cell migration, invasion, metastasis, and drug resistance. Although these studies identified various biological functions of Nutlin‑3, our understanding of the exact molecular mechanisms of Nutlin‑3‑mediated antitumor activity remains incomplete. In this study, we elucidated a role of Nutlin‑3 in reversing the epithelial‑mesenchymal transition (EMT) in gemcitabine-resistant (GR) hepatocellular carcinoma (HCC) cells. We assessed the effect of Nutlin‑3 treatment on cell growth, migration, and invasion in both parental HCC cells and GR HCC cells. Moreover, we detected the expression of EMT markers in GR HCC cells treated with Nutlin‑3 by real‑time RT‑PCR and western blot analysis, respectively. We found that Nutlin-3 inhibited cell migration and invasion in the GR HCC cells. Additionally, Nutlin‑3 treatment increased E-cadherin protein levels, but decreased the protein levels of vimentin, Snail and Slug in the GR HCC cells. Furthermore, we found that Smad2 was highly expressed in the GR HCC cells compared with their parental HCC cells, and Nutlin-3 treatment downregulated Smad2 expression in the GR HCC cells. Depletion of Smad2 retarded cell migration and regulated the expression of EMT markers in GR HCC cells similarly to Nutlin‑3 treatment. Our findings highlight an important role of Nutlin‑3 in reversing EMT in GR cells through regulation of Smad2 expression, suggesting that Nutlin-3 could be a potential agent for the treatment of HCC patients with gemcitabine resistance.

Curcumin (diferuloyl methane) is an antioxidant that exerts antiproliferative and apoptotic effects and has anti-invasive and anti-metastatic properties. Evidence strongly implicates that epithelial-mesenchymal transition (EMT) is involved in malignant progression affecting genes such as Slug, AXL and Twist1. These genes are abnormally expressed in many tumors and favor metastasis. The purpose of this study was to determine the potential effect of curcumin on EMT, migration and invasion. Triple-positive and triple-negative breast cancer cell lines for estrogen receptor (ER), progesterone receptor (PgR) and HER/neu were used: i) MCF-10F, a normal immortalized breast epithelial cell line (negative), ii) Tumor2, a malignant and tumorigenic cell line (positive) derived from Alpha5 cell line injected into the immunologically depressed mice and transformed by 60/60 cGy doses of high LET (linear energy transfer) α particles (150 keV/µm) of radiation and estrogen, and iii) a commercially available MDA-MB‑231 (negative). The effect of curcumin (30 µM for 48 h) was evaluated on expression of EMT-related genes by RT-qPCR. Results showed that curcumin decreased E-cadherin, N-cadherin, β-catenin, Slug, AXL, Twist1, Vimentin and Fibronectin protein expression, independently of the positivity of the markers in the cell lines. Curcumin also decreased migration and invasive capabilities in comparison to their own controls. It can be concluded that curcumin influenced biochemical changes associated with EMT-related genes that seems to promote such transition and are at the core of several signaling pathways that mediate the transition. Thus, it can be suggested that curcumin is able to prevent or delay cancer progression through the interruption of this process.

As a new strategy, radio-gene therapy was widely used for the treatment of cancer patients in recent few years. Slug was involved in the radioresistance of various cancers and has been found to have an anti-apoptotic effect. This study aims to investigate whether the modulation of Slug expression by siRNA affects oral squamous cell carcinoma sensitivity to X-ray irradiation through upregulating PUMA. Two oral squamous cell carcinoma cell lines (HSC3 and HSC6) were transfected with small interfering RNA (siRNA) targeting Slug and subjected to radiotherapy in vitro. After transfection with Slug siRNA, both HSC3 and HSC6 cells showed relatively lower expression of Slug and higher expression of PUMA. The Slug siRNA transfected cells showed decreased survival and proliferation rates, an increased apoptosis rate and enhanced radiosensitivity to X-ray irradiation. Our results revealed that Slug siRNA transfection in combination with radiation increased the expression of PUMA, which contributed to radiosensitivity of oral squamous cell carcinoma cells. Thus, controlling the expression of Slug might contribute to enhance sensitivity of HSC3 and HSC6 cells toward X-ray irradiation in vitro by upregulating PUMA.

Laryngeal squamous cell carcinoma (LSCC) is one of the most common malignant tumors, and the main cause of death is metastasis. Overexpression of aurora kinase A (AURKA) plays an important role in the metastasis of LSCC. However, the mechanism by which AURKA promotes the metastasis of LSCC is poorly understood. Recent accumulating evidence indicates that epithelial-mesenchymal transition (EMT) may be one of the mechanisms of tumor metastasis. In the present study, we studied whether AURKA may induce EMT to promote the metastasis of LSCC. CCK-8 and plate colony-formation assays were carried out to show that AURKA significantly promoted the proliferation of Hep2 cells. Immunofluorescence staining and western blotting showed that EMT-related proteins changed in a time-dependent manner along with the alteration of AURKA, with decreased expression of N-cadherin, vimentin and slug and increased expression of E-cadherin. Additionally, downregulation of the expression of AURKA inhibited FAK/PI3K pathway activity. Inhibition of the FAK/PI3K pathway caused less mesenchymal-like characteristics and reduced the mobility, migration and invasion of Hep2 cells. In conclusion, AURKA may induce EMT to promote metastasis via activation of the FAK/PI3K pathway in LSCC. Those regulatory factors may present new diagnostic biomarkers and potential therapeutic targets for LSCC.

Metastasis is the main cause of death in osteosarcoma. Targeting the process of metastasis is a main strategy for osteosarcoma therapy. As a traditional Chinese medicine, Zanthoxylum nitidum (Roxb) has been applied to treat various diseases, including cancer. However, no evidence has been shown on the anti-metastasis effect of nitidine chloride (NC) that was extracted from Zanthoxylum nitidum (Roxb) on osteosarcoma cells, or its underling mechanisms. In the present study, we aimed to demonstrate the role of NC on the migration and invasion of osteosarcoma cells. Viability and proliferation of osteosarcoma cells were examined by MTT assay. Then, by appling scratch wound healing assay and Transwell assays, we evaluated migratory and invasive ability of the cells, respectively. Moreover, the expression of epithelial-to-mesenchymal transition (EMT) markers were determined after treatment with NC. Furthermore, the expression of Akt, GSK-3β and Snail were detected by western blot analysis. In addition, the GSK-3β activity was examined by GSK-3β kinase assay. Finally, an inhibitor of GSK-3β, lithium chloride (LiCl) was applied to testify the effect of NC on the expression of EMT markers and Snail. We found that the proliferative, migratory and invasive ability of the U2OS osteosarcoma cells were all suppressed when treated with NC. NC increased the expression of E-cadherin and decreased the expression of N-cadherin, vimentin and fibronectin in a dose-dependent manner. NC also exerted its ability to suppress the phosphorylation of Akt and GSK-3β so as to activate GSK-3β. Then, by using an GSK-3β inhibitor, LiCl, we revealed the effect of GSK-3β in the expression of EMT markers. The expression of Snail was inhibited when treated with NC and LiCl also reversed the NC-inhibited Snail expression. Taken together, these results revealed that NC suppressed EMT and decreased the invasive ability of osteosarcoma cells via the Akt/GSK-3β/snail signaling pathway.

miR-410-3p acts as an oncogene or tumor-suppressor gene in various types of cancer. However, its role in breast cancer remains unknown. In the present study, expression of miR-410-3p in 30 breast cancer and paired adjacent normal tissues was detected by RT-qPCR. The expression of miR-410-3p was downregulated in 76.7% of the breast cancer samples. To further validate the expression of miR-410-3p in breast cancer, we analyzed miR-410-3p expression profiling data set from The Cancer Genome Atlas (TCGA) including 683 breast cancer and 87 normal breast tissues. We observed that the expression of miR-410-3p was downregulated in breast cancer tissues. Next, we investigated the influence of miR-410-3p on cell proliferation by transiently transfecting the miR-410-3p mimic or inhibitor, as well as their corresponding controls in the MDA-MB-231 and MCF7 cell lines. miR-410-3p overexpression reduced cell growth, colony formation and the number of EdU-positive cells in the MDA-MB-231 cells. In contrast, inhibition of miR-410-3p in the MCF7 cells resulted in a higher proliferation rate as assessed by MTT assay, plate colony formation and EdU assays. Furthermore, miR-410-3p inhibited epithelial-mesenchymal transition. In addition, Snail was found to be a direct target of miR-410-3p based on a luciferase assay. Overexpression of Snail was able to rescue the effect of miR-410-3p in breast cancer cells. Moreover, miR‑410-3p was inversely expressed with Snail in breast cancer samples. Our data provide new knowledge regarding the role of miR-410-3p in breast cancer progression.

Accumulating evidence has shown that aberrantly expressed microRNAs (miRNAs) are associated with tumor development and progression. Our previous study found that microRNA-375 (miR-375) was downregulated in colorectal cancer (CRC), but little is known concerning the role of miR-375 and the related mechanism in CRC development. The proliferation, invasion and migration effects were investigated by Cell Counting Kit-8 (CCK-8), colony formation and Transwell assays with or without Matrigel. In addition, candidate target genes were screened and validated by luciferase reporter and western blot assays. In addition, western blot analysis was performed to explore the molecular mechanisms associated with epithelial‑mesenchymal transition (EMT). It was found that miR-375 inhibited proliferation, invasion and migration in DLD1 and HCT8 cells. In addition, miR-375 negatively regulated Sp1 transcription factor (SP1) protein by directly binding to the 3'-untranslated region (3'-UTR). Furthermore, it was found that miR-375 regulated matrix metalloproteinase 2 (MMP2) and EMT-associated genes, E-cadherin, vimentin, snail, N-cadherin and β-catenin. In conclusion, miR-375 inhibited the proliferation, invasion and migration by directly targeting SP1 and regulating MMP2 and EMT-associated genes.

Previous studies have found that inhibitor of growth 4 (ING4), a tumor suppressor, is reduced in human colorectal cancer (CRC), and is inversely correlated with clinical Dukes' stage, histological grade, lymph node metastasis and microvessel density (MVD). However, its underlying mechanism remains undetermined. In the present study, we analyzed ING4 expression in a panel of human CRC cells using low (LS174T and SW480) and high (LoVo and SW620) metastatic cell lines. We demonstrated that both the low and high metastatic CRC cells exhibited a lower level of ING4 compared to the level in normal human colorectal mucous epithelial FHC cells. Furthermore, ING4 expression in high metastatic CRC cells was less than that in low metastatic CRC cells. We then generated a lentivirus construct expressing ING4 and green fluorescent protein (GFP), established a ING4-stably transgenic LoVo CRC cell line, and investigated the effect of lentiviral-mediated ING4 expression on high metastatic LoVo CRC cells. Gain-of-function studies revealed that ING4 significantly inhibited LoVo CRC cell growth and invasion in vitro and induced cell cycle G1 phase arrest. Moreover, ING4 obviously suppressed LoVo CRC subcutaneously xenografted tumor growth and reduced tumor MVD in vivo in athymic BALB/c nude mice. Mechanistically, ING4 markedly upregulated P21 and E-cadherin but downregulated cyclin E, interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF), Snail1, N-cadherin and vimentin in the LoVo CRC cells. Our data provide compelling evidence that i) ING4 suppresses CRC growth possibly via induction of G1 phase arrest through upregulation of P21 cyclin-dependent kinase (CDK) inhibitor and downregulation of cyclin E as well as inhibition of tumor angiogenesis through reduction of IL-6, IL-8 and VEGF proangiogenic factors; ii) ING4 inhibits CRC invasion and metastasis probably via a switch from mesenchymal marker N-cadherin to epithelial marker E-cadherin through downregulation of Snail1 epithelial-mesenchymal transition (EMT)-inducing transcription factor (EMT-TF).