ERp29 controls invasion and metastasis of gastric carcinoma by inhibition of epithelial-mesenchymal transition via PI3K/Aktsignaling pathway

The role of ERp29/FOS/EMT pathway in excessive apoptosis of placental trophoblast cells in intrahepatic cholestasis of pregnancy

BACKGROUND

Abnormal bile acid metabolism leading to changes in placental function during pregnancy. To determine whether endoplasmic reticulum protein 29 (ERp29) can mediate the pregnancy effects of cholestasis by altering the level of trophoblast cell apoptosis.

METHODS

ERp29 in serum of 66 intrahepatic cholestasis of pregnancy (ICP) pregnant women and 74 healthy were detected by ELISA. Subcutaneous injection of ethinyl estradiol (E2) was used to induce ICP in pregnant rats. Taurocholic acid (TCA) was used to simulate the ICP environment, and TGF-β1 was added to induce the epithelial mesenchymal transformation (EMT) process. The scratch, migration, and invasion test were used to detect the EMT process. ERp29 overexpression/knockdown vector were constructed and transfected to verify the role of ERp29 in the EMT process. Downstream gene was obtained through RNA-seq.

RESULTS

Compared with the healthy pregnant women, the expression levels of ERp29 in serum of ICP pregnancy women were significantly increased (P < 0.001). ERp29 in the placenta tissue of the ICP pregnant rats increased significantly, and the level of apoptosis increased. The placental tissues of the ICP had high expression of E-cadherin and low expression of N-cadherin, snail1, vimentin. After HTR-8/SVneo cells were induced by TCA, EMT was inhibited, while the ERp29 increased. Cell and animal experiments showed that, knockdown of ERp29 reduced the inhibition of EMT, the ICP progress was alleviated. Overexpression of FOS salvaged the inhibitory effects of ERp29 on cell EMT.

DISCUSSION

The high level of ERp29 in placental trophoblast cells reduced FOS mRNA levels, inhibited the EMT process and aggravated the occurrence and development of ICP.

Euchromatic histone lysine methyltransferase 2 facilitates radioresistance in prostate cancer by repressing endoplasmic reticulum protein 29 transcription

Prostate cancer is one of the most common cancers in men. This study was conducted to investigate the role of euchromatic histone lysine methyltransferase 2 (EHMT2) and endoplasmic reticulum protein 29 (ERP29) in the progression of radioresistance in prostate cancer. The expression of EHMT2 and ERP29 in prostate cancer cells and during the progression of radioresistance was detected using quantitative reverse transcription-polymerase chain reaction and western blotting, and the interaction between EHMT2 and ERP29 was investigated. The proliferation of transfected cells under x-ray irradiation was determined using the methyl thiazolyl tetrazolium and colony formation assays. Flow cytometry was used to analyze the apoptosis of the transfected cells under x-ray irradiation. Nude mice were subcutaneously injected with prostate cancer (DU145) cells stably transfected with sh-ERP29 or sh-NC. The effect of ERP29 expression on radioresistance in nude mice was assessed by x-ray irradiation. The expression of EHMT2 was upregulated and that of ERP29 was downregulated in prostate cancer cells during radioresistance progression. EHMT2 downregulation suppressed radioresistance in DU145 and androgen-sensitive prostate cancer (LNCaP) cells. In irradiated DU145 cells, EHMT2 inhibition decreased the number of colonies and accelerated apoptosis. The transcription of ERP29 was suppressed by EHMT2 by upregulating H3K9me2 and downregulating H3K4me3, thereby regulating radioresistance in prostate cancer cells. In addition, the downregulation of ERP29 promoted the progression of radioresistance in prostate cancer cells in nude mice. EHMT2 promotes radioresistance in prostate cancer cells by repressing ERP29 transcription.

ERp44 Regulates the Proliferation, Migration, Invasion, and Apoptosis of Gastric Cancer Cells Via Activation of ER Stress

Gastric cancer (GC) is one of the most prevalent malignancies worldwide. Endoplasmic reticulum (ER) stress plays a key role in the progression of GC. Rapid proliferation of tumor cells interferes with ER homeostasis, leading to ER stress and triggering unfolded protein response. Therefore, it is very necessary to investigate abnormally expressed ER resident proteins (ERp) in cancer cells. This study aimed to investigate the possible roles of ERp44. The mRNA and protein expression of genes were detected using qRT-PCR and western blot. Cell apoptosis was calculated using flow cytometry. Cell proliferation was determined using CCK-8 and colony formation assay. Cell migration was detected by wound healing, and cell invasion was measured by transwell assay. We found that ERp44 was obviously decreased in GC tissues. Furthermore, ERp44 overexpression distinctly suppressed the proliferation, migration, and invasion of MGC-803 and KATO III cells. In contrast, apoptosis was promoted by ERp44 overexpression. Furthermore, mechanistic studies revealed that overexpression of ERp44 inhibited malignant biological processes by regulating the eIF-2α/CHOP signaling pathway. Taken together, our data demonstrated that ERp44 regulated the proliferation, migration, invasion, and apoptosis via ERp44/eIF-2α/CHOP axis in GC. Targeting the ERp44and ER stress may be a promising strategy for GC.

ERp29 forms a feedback regulation loop with microRNA-135a-5p and promotes progression of colorectal cancer

Expression of endoplasmic reticulum (ER) stress-associated genes is often dysregulated in cancer progression. ER protein 29 (ERp29) is abnormally expressed in many neoplasms and plays an important role in tumorigenesis. Here, we showed ERp29 is a novel target for microRNA-135a-5p (miR-135a-5p) to inhibit the progression of colorectal cancer (CRC); correspondingly, ERp29 acts as an oncoprotein in CRC by promoting proliferation and metastasis of CRC cells, and suppressing apoptosis of the cells. More importantly, we found that miR-135a-5p expression is reversely upregulated by ERp29 through suppressing IL-1β-elicited methylation of miR-135a-5p promoter region, a process for enterocyte to maintain a balance between miR-135a-5p and ERp29 but dysregulated in CRC. Our study reveals a novel feedback regulation loop between miR-135a-5p and ERp29 that is critical for maintaining appropriate level of each of them, but partially imbalanced in CRC, resulting in abnormal expression of miR-135a-5p and ERp29, which further accelerates CRC progression. We provide supporting evidence for ERp29 and miR-135a-5p as potential biomarkers for diagnosis and treatment of CRC.

Oral administration of EGCG solution equivalent to daily achievable dosages of regular tea drinkers effectively suppresses miR483-3p induced metastasis of hepatocellular carcinoma cells in mice

The effect of non-cytotoxic doses of epigallocatechin-3-gallate (EGCG) on the metastatic capability of human hepatocellular carcinoma (HCC) cells was investigated in vitro and in vivo. miR483-3p, a microRNA whose expression correlates inversely with survival and positively with disease progression in HCC patients, was found to promote HCC cell migration and invasion in vitro as well as lung metastasis in nude mice established by the tail-vein injection of HCC cells. The induction of reactive oxygen species (ROS) and downregulation of antioxidant defense factors Nrf2 and SOD2 appeared to be an important underlying mechanism and treatment with a non-cytotoxic dose of EGCG effectively reversed the miR483-3p-induced enhancement of HCC cell migration and invasion in vitro. Moreover, administration through drinking water at doses (0.1% and 0.5% EGCG solution, respectively) equivalent to the intake of regular to heavy tea drinkers could also significantly inhibit lung metastasis of HCC cells based on the estimation from the USDA Database for the Flavonoid Content of Selected Foods and FDA guidelines for the conversion of animal dose to human equivalent dose. EGCG also significantly counteracted the miR483-3p-induced alteration in the expression of epithelial-mesenchymal transition (EMT) markers, E-cadherin and vimentin, and downregulated the endogenous expression of miR483-3p in HCC cells through an epigenetic mechanism that led to the hypermethylation of the miR483-3p promoter region. The data from our study illustrate that miR483-3p promotes HCC metastasis likely through the induction of oxidative stress and uncover a novel role of EGCG for protection against miR483-3p-mediated HCC metastasis via the epigenetic modulation of miR483-3p expression. These findings therefore provide further evidence supporting that regular tea consumption may contribute to protection against miR-483-3p-induced ROS and the associated HCC progression.

Guanine nucleotide binding protein like-1 (GNL1) promotes cancer cell proliferation and survival through AKT/p21 CIP1 signaling cascade

Human guanine nucleotide binding protein like 1 (GNL1) is an evolutionary conserved putative nucleolar GTPase belonging to the HSR1_MMR1 subfamily of GTPases. GNL1 was found to be highly up-regulated in various cancers. Here, we report for the first time that GNL1 inhibits apoptosis by modulating the expression of Bcl2 family of proteins and the cleavage of caspases 7 and 8. Furthermore, GNL1 protects colon cancer cells from chemo-drug-induced apoptosis. Interestingly, GNL1 up-regulates the expression of p53 and its transcriptional target, p21 but the up-regulation of p21 was found to be p53 dependent as well as independent mechanisms. Our results further demonstrate that GNL1 promotes cell growth and survival by inducing cytoplasmic retention and stabilization of p21 through AKT-mediated phosphorylation. In addition, GNL1 failed to inhibit apoptosis under p21 knockdown conditions which suggests the critical role of p21 in GNL1-mediated cell survival. Finally, an inverse correlation of GNL1, p21, and AKT expression in primary colon and breast cancer with patient survival suggests their critical role in tumorigenesis. Collectively, our study reveals that GNL1 executes its antiapoptotic function by a novel mechanism and suggests that it may function as a regulatory component of the PI3K/AKT/p21 signaling network to promote cell proliferation and survival in cancers.

Role of a genetic variation in the microRNA-4421 binding site of ERP29 regarding risk of oropharynx cancer and prognosis

We conducted a two-stage association study on patients with oropharynx (OP) squamous cell carcinoma (SCC) and healthy controls to identify single nucleotide variants (SNVs) located at the microRNA (miR)-binding sites of carcinogenesis genes associated with risk and prognosis of the disease. In stage 1, 49 patients and 49 controls were analyzed using Genome-Wide Human SNV Arrays to identify variants in the 3′-untranslated region (3′-UTR) of carcinogenesis-related genes, and one SNV was selected for data validation in stage 2 by TaqMan assays in 250 OPSCC patients and 250 controls. The ERP29 c.*293A > G (rs7114) SNV located at miR-4421 binding site was selected for data validation among 46 SNVs. The ERp29 and miR-4421 levels were evaluated by quantitative-PCR and Western blotting. Interaction between miR-4421 with 3′-UTR of ERP29 was evaluated by luciferase reporter assay. Event-free survival (EFS) was calculated by Kaplan–Meier and Cox methods. ERP29 GG variant genotype was more common in OPSCC patients than in controls (6.4% vs 3.6%, p = 0.02; odds ratio: 5.67; 95% confidence interval (CI) 1.27–25.26). Shorter EFS were seen in the base of tongue (BT) SCC patients with GG genotype (0.0% vs 36.2%, p = 0.01; hazard ratio: 2.31; 95% CI: 1.03–5.15). Individuals with ERP29 AG or GG genotypes featured lower levels of ERP29 mRNA (p = 0.005), ERp29 protein (p < 0.001) and higher levels of miR-4421 (p = 0.02). The miR-4421 showed more efficient binding with 3′-UTR of the variant G allele when compared with wild-type allele A (p = 0.001). Our data suggest that ERP29 rs7114 SNV may alter the risk and prognosis of OPSCC due to variation in the ERp29 production possibly modulated by miR-4421.

LncRNA PCGEM1 accelerates non-small cell lung cancer progression via sponging miR-433-3p to upregulate WTAP

Background

Non-small cell lung cancer (NSCLC) is one of the most common malignant tumors all over the world. In recent years, long non-coding RNAs (lncRNAs) have been proven to participate in the development of different cancers, including NSCLC. PCGEM1 prostate-specific transcript (PCGEM1) is the lncRNA which is associated with the progression of several cancers. Nevertheless, in NSCLC, the specific functions of PCGEM1 are not yet clear.

Methods

The real-time quantitative polymerase chain reaction (qPCR) was utilized to test the expression of PCGEM1 in NSCLC cells. Functional experiments, including cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2’-deoxyuridine (EdU) assay, flow cytometry analysis and transwell assays were utilized to estimate cell proliferation, migration, invasion and apoptosis. Meanwhile, RNA pull down assay and luciferase reporter assay were utilized to evaluate the correlation of miR-433-3p with PCGEM1 or WT1 associated protein (WTAP).

Result

PCGEM1 was highly expressed in NSCLC cells, while miR-433-3p was lowly expressed in NSCLC cells. PCGEM1 silencing or miR-433-3p overexpression inhibited cell proliferation, migration and invasion but accelerated cell apoptosis. MiR-433-3p was proven be sponged by PCGEM1. Besides, WTAP was the target of miR-433-3p and it accelerated the progression of NSCLC. In the end, rescue experiments indicated that overexpression of WTAP or knockdown of miR-433-3p reversed the inhibited roles of silencing PCGEM1 on cell behavior.

Conclusions

PCGEM1 accelerates NSCLC progression via sponging miR-433-3p to upregulate WTAP.

BCAP31, a cancer/testis antigen-like protein, can act as a probe for non-small-cell lung cancer metastasis

Non-small-cell lung cancer (NSCLC) represents most of lung cancers, is often diagnosed at an advanced metastatic stage. Therefore, exploring the mechanisms underlying metastasis is key to understanding the development of NSCLC. The expression of B cell receptor-associated protein 31 (BCAP31), calreticulin, glucose-regulated protein 78, and glucose-regulated protein 94 were analyzed using immunohistochemical staining of 360 NSCLC patients. It resulted that the high-level expression of the four proteins, but particularly BCAP31, predicted inferior overall survival. What’s more, BCAP31 was closely associated with histological grade and p53 status, which was verified by seven cohorts of NSCLC transcript microarray datasets. Then, three NSCLC cell lines were transfected to observe behavior changes BCAP31 caused, we found the fluctuation of BCAP31 significantly influenced the migration, invasion of NSCLC cells. To identify the pathway utilized by BCAP31, Gene Set Enrichment Analysis was firstly performed, showing Akt/m-TOR/p70S6K pathway was the significant one, which was verified by immunofluorescence, kinase phosphorylation and cellular behavioral observations. Finally, the data of label-free mass spectroscopy implied that BCAP31 plays a role in a fundamental biological process. This study provides the first demonstration of BCAP31 as a novel prognostic factor related to metastasis and suggests a new therapeutic strategy for NSCLC.

ERp29 affects the migratory and invasive ability of human extravillous trophoblast HTR-8/SVneo cells via modulating the epithelial-mesenchymal transition

Dysfunction of trophoblast metastasis into the endometrium is the main cause of pre-eclampsia (PE); however, the factors affecting this process are still unclear. In this study, we found that endoplasmic reticulum protein 29 (ERp29), one molecular chaperone of the endoplasmic reticulum, was aberrantly upregulated in the placenta of pre-eclamptic patients compared with healthy controls. Then, an in vitro study using human extravillous trophoblast HTR-8/SVneo cells showed that ERp29 upregulation could inhibit the migratory and invasive ability of HTR-8/SVneo cells, while ERp29 downregulation had the opposite effect. Mechanical experiments confirmed that ERp29 blocked trophoblast metastasis via inhibiting the process of epithelial-mesenchymal transition and affecting the Wnt/β-catenin signaling pathway. In conclusion, this study revealed the important role of ERp29 in trophoblast metastasis and improved the mechanical understanding of PE occurrence.

High glucose regulates ERp29 in hepatocellular carcinoma by LncRNA MEG3-miRNA 483-3p pathway

AIMS

Blood glucose dysregulation is an adverse factor in the prognosis of hepatocellular carcinoma (HCC). Endoplasmic reticulum (ER) is thought to be crucial component in the development of cancer and diabetes. This study aimed to investigate the mechanisms of poor outcomes in HCC patients with diabetes.

MAIN METHODS

ER protein 29 (ERp29) was predicted by proteomics, immunohistochemistry, Western blot, Cell Counting Kit-8 (CCK-8) and cell scratch test were used to identify the expression and biological effects of ERp29 under high glucose (HG) in HCC cells. Bioinformatics found a competing endogenous RNAs (ceRNAs) regulatory network between microRNA-483-3p (miR-483-3p) and Long noncoding RNA (LncRNA MEG3), the above methods also were used to identify their expression, biological effects and their roles of HG on regulation of REp29 in HCC cells, Dual-luciferase reporter assay was carried out to study the interaction of ERp29 with miR-483-3p and miR-483-3p with MEG3.

KEY FINDINGS

HG upregulated miR-483-3p expression in HCC cells and miR-483-3p overexpression suppressed ERp29 expression and also increased HCC cell proliferation and migration. Furthermore, we found that MEG3 was decreased in HCC cells incubated in medium with high glucose and knockdown of MEG3 downregulated ERp29 expression. Bioinformatics analysis found that MEG3 mediated its protective effects via binding to miR-483-3p.

SIGNIFICANCE

Overall, our study established a novel regulatory network of LncRNA MEG3/miR483-3p/ERp29 in HCC which may be helpful in better understanding the effect of high glucose on poor prognosis of HCC and in exploring new diagnostic and therapeutic tools for managing HCC in patients with diabetes.

Orthotopic Patient-Derived Xenografts of Gastric Cancer to Decipher Drugs Effects on Cancer Stem Cells and Metastatic Dissemination

Gastric cancer is the third leading cause of cancer mortality worldwide. Cancer stem cells (CSC) are at the origin of tumor initiation, chemoresistance, and the formation of metastases. However, there is a lack of mouse models enabling the study of the metastatic process in gastric adenocarcinoma (GC). The aims of this study were to develop original mouse models of patient-derived primary GC orthotopic xenografts (PDOX) allowing the development of distant metastases as preclinical models to study the anti-metastatic efficiency of drugs such as the phosphatidylinositol 3-kinase (PI3K) inhibitor Buparlisib (BKM120). Luciferase-encoding cells generated from primary GC were injected into the stomach wall of immunocompromised mice; gastric tumor and metastases development were followed by bioluminescence imaging. The anti-CSC properties of BKM120 were evaluated on the GC cells’ phenotype (CD44 expression) and tumorigenic properties in vitro and in vivo on BKM120-treated mice. After eight weeks, PDOX mice formed tumors in the stomach as well as distant metastases, that were enriched in CSC, in the liver, the lung, and the peritoneal cavity. BKM120 treatment significantly inhibited the CSC properties in vitro and reduced the number of distant metastases in mice. These new preclinical models offer the opportunity to study the anti-metastatic efficiency of new CSC-based therapeutic strategies.

Endoplasmic reticulum proteostasis control and gastric cancer

The endoplasmic reticulum (ER) is the primary organelle responsible for the synthesis, modification, folding and secretion of proteins, especially in specialized secretory cells. It also contributes to the maintenance of cellular functions, such as Ca²⁺ storage, lipogenesis, gluconeogenesis, and organelle biogenesis. Cellular stress conditions, such as glucose deprivation, hypoxia and disturbance of Ca²⁺ homeostasis, may increase the risk of protein misfolding and perturb proteostasis. This activates ER stress and triggers the unfolded protein response (UPR), leading to either the restoration of homeostasis or cell death. ER stress and UPR have been shown to play crucial roles in the pathogenesis, progression and treatment response of various cancers. In gastric cancer (GC), one of the most aggressive cancer types, critical functions of ER stress signaling have also started to emerge. Herein, we summarize the current knowledge linking ER stress and UPR to GC; we also discuss the possible nodes of therapeutic intervention and propose directions of future research.

Paired box 8 suppresses tumor angiogenesis and metastasis in gastric cancer through repression of FOXM1 via induction of microRNA-612

Background

Paired box 8 (PAX8) has been documented to be downregulated in gastric cancer. However, its biological function in this malignancy is poorly understood.

Methods

In the present work, we investigated the effects of PAX8 overexpression and knockdown on the aggressive phenotype of gastric cancer cells. We further checked the involvement of forkhead box M1 (FOXM1), a ubiquitously expressed oncogene that can facilitate gastric cancer progression, in the action of PAX8.

Results

Ectopic expression of PAX8 blocked the migration and invasion of both AGS and SGC-7901 cells, but had no effect on cell proliferation. Conversely, knockdown of PAX8 enhanced gastric cancer cell migration and invasion. PAX8 overexpression inhibited epithelial-mesenchymal transition (EMT) and pro-angiogenic activity of gastric cancer cells. Mechanistically, PAX8 overexpression downregulated FOXM1 by stimulating microRNA (miR)-612 expression. Ectopic expression of miR-612 recapitulated the effect of PAX8 overexpression on gastric cancer cells, causing an inhibition of migration, invasion, EMT, and angiogenesis. Knockdown of miR-612 or overexpression of FOXM1 significantly reversed the tumor-suppressive activity of PAX8. In vivo studies further demonstrated that PAX8 overexpression restrained tumor angiogenesis and metastasis in nude mice, which was accompanied by increased expression of miR-612 and decreased expression of FOXM1.

Conclusions

PAX8 exerts a tumor-suppressive effect against gastric cancer cells, largely through induction of miR-612 and repression of FOXM1. Therefore, restoration of PAX8 expression may offer therapeutic benefits in the treatment of gastric cancer.

Integrated analysis of long noncoding RNA expression profiles in lymph node metastasis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, and metastasis of HCC is the leading cause of poor prognosis. Among all the extrahepatic metastases, lymph node metastasis (LNM) is common, second only to lung metastasis. However, the pathogenesis of HCC LNM remains largely unknown.

METHODS

Microarray was performed to investigate the long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in serum samples from HCC LNM patients (N = 4) and HCC non-LNM controls (N = 5). Subsequently, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was applied to validate the expression levels of randomly selected differential lncRNAs and mRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were employed to explore the potential functions of differentially expressed mRNAs. Co-expression networks were further constructed to elucidate the interactions of the differential genes and to speculate on the potential functions of the dominant lncRNAs. In this research, we attempted to illuminate the correlations between lncRNA and HCC LNM.

RESULTS

Compared with the non-LNM group, a total of 234 lncRNAs and 58 mRNAs were obtained as significantly dysregulated genes in LNM group (p < 0.05, fold change ≥ 2). Functional enrichment analyses showed that upregulated mRNAs are mostly enriched for glucose-6-phosphate dehydrogenase activity, biotin binding and AP-3 adaptor complex, while the downregulated mRNAs are enriched for macrophage colony-stimulating factor receptor binding, succinate-CoA ligase activity and palmitoyltransferase activity. In addition, coexpression network revealed that the dominant lncRNAs are potential participants of protein metabolic process, integral component of membrane, RNA binding, Golgi apparatus, as well as focal adhesion pathway.

CONCLUSION

This study first revealed the expression profiles and potential functions of dysregulated lncRNAs and mRNAs in HCC LNM, which may provide novel clues for further studies on HCC LNM.

Biological role and clinical value of miR-99a-5p in head and neck squamous cell carcinoma (HNSCC): A bioinformatics-based study

MicroRNAs (miRNAs) are confirmed to be tumor promoters or suppressors in multiple squamous cell carcinomas (SCCs). miR‐99a‐5p has been demonstrated to be downregulated in cancerous tissues, but its functional role in head and neck SCC (HNSCC) and its mechanism of action have not been fully elucidated. Here, we studied the expression of miR‐99a‐5p in HNSCC and performed a clinical value assessment and then extracted mature expression data from The Cancer Genome Atlas (TCGA) and microarrays from Gene Expression Omnibus (GEO). Furthermore, biological analysis was constructed via online prediction tools. The results revealed that miR‐99a‐5p expression was markedly lower in HNSCC tissues than in normal tissues, which also showed significance in the prognosis of HNSCC. However, its diagnostic value could not be verified due to the lack of body fluid samples. Additionally, miR‐99a‐5p was expressed at higher levels in patients with low histological grade neoplasms than those with high histological grade neoplasms. The age of the patient might also be a possible clinical parameter affecting miR‐99a‐5p expression. Furthermore, miR‐99a‐5p significantly influenced HNSCC progression by regulating the PI3K‐Akt signaling pathway, in which the key target genes were upregulated in 519 HNSCC tissues compared to 44 normal tissues, as determined by the Gene Expression Profiling Interactive Analysis (GEPIA). In conclusion, our study may provide insights into the expression and mechanism of miR‐99a‐5p in HNSCC. Further studies are required to elucidate the role of miR‐99a‐5p and its potential clinical applications for HNSCC.

ATPR-induced G0 /G1 phase arrest in gastric cancer cells by regulating the binding of 14-3-3ε and filamin A

4‐amino‐2‐trifluoromethyl‐phenyl retinate (ATPR) was able to induce the G₀/G₁ phase arrest in gastric cancer SGC‐7901 cells by downregulating 14‐3‐3ε. However, the mechanisms underlying this effect have not been fully elucidated. Because 14‐3‐3ε functions as a molecular chaperone on cell cycle regulation, the interaction between 14‐3‐3ε and the target proteins is worth an in‐depth study. In this study, the use of targeting proteomics identified 352 14‐3‐3ε‐binding proteins in SGC‐7901 cells. Analysis of gene ontology (GO) was performed using PANTHER to annotate the biological processes, protein classes, and pathways of these proteins. In 25 cell cycle‐related proteins, filamin A was reduced following ATPR treatment, and this change was validated by immunoprecipitation. The cell cycle was arrested at the G₀/G₁ phase following ATPR treatment or filamin A silencing in SGC‐7901 cells. Furthermore, subcellular expression analysis showed that 14‐3‐3ε and filamin A were transferred from the cytoplasm to the nucleus after ATPR treatment. On the other hand, overexpression of 14‐3‐3ε, in SGC‐7901 cells, resulted in an increase in the total cellular level of filamin A and an increase in the subcellular localization of filamin A in the cytoplasm. ATPR treatment of the 14‐3‐3ε overexpression cells decreased the total level of filamin A and redistributed filamin A protein from the cytoplasm to the nucleus. Immunohistochemical analysis showed that the expression levels of 14‐3‐3ε and filamin A in gastric cancer tissues were significantly higher, with a predominant localization in the cytoplasm, compared to the levels in matched tissues. Taken together, our results suggest that ATPR can induce nuclear localization of filamin A by reducing the binding of 14‐3‐3ε and filamin A, which may be the mechanism of ATPR‐induced G₀/G₁ phase arrest.

12-Lipoxygenase promotes invasion and metastasis of human gastric cancer cells via epithelial-mesenchymal transition

The role of 12-lipoxygenase (12-LOX) in tumorigenesis has been well established in several types of human cancer, including gastric cancer. It was reported that epithelial-mesenchymal transition (EMT) contributes to tumor invasion and metastasis. However, whether 12-LOX promotes the invasion and metastasis of human gastric cancer cells via EMT remains to be elucidated. In the present study, the expression of 12-LOX and EMT markers, N-cadherin and E-cadherin, was evaluated in gastric cancer and adjacent normal mucosa samples by immunohistochemical analysis. 12-LOX-overexpressing gastric cancer cells were established via lentiviral transfection of SCG-7901 cells. Wound-healing and Transwell assays were performed to examine the regulation of cell metastasis and invasion by 12-LOX. Furthermore, the regulation of N-cadherin expression by 12-LOX was evaluated using reverse transcription-quantitative polymerase chain reaction and western blotting. The results revealed that the expression of 12-LOX and N-cadherin was significantly higher in gastric cancer compared with that in adjacent normal mucosa tissues (P<0.05). By contrast, the expression of E-cadherin was significantly decreased in gastric cancer compared with that in adjacent normal mucosa tissues (P<0.05). Furthermore, the expression of 12-LOX was positively associated with N-cadherin expression in gastric cancer tissues. 12-LOX-overexpressing gastric cancer cells exhibited significantly increased invasion and migration abilities compared with the empty vector and control groups. The expression of N-cadherin in 12-LOX-overexpressing gastric cancer cells was increased compared with that in the empty vector and control groups. The present study suggests that EMT may be involved in the promotion of the invasion and metastasis of human gastric cancer cells by 12-LOX.