RETRACTED ARTICLE: Tumor suppressor microRNA-31 inhibits gastric carcinogenesis by targeting Smad4 and SGPP2

Utilizing an Endogenous Progesterone Receptor Reporter Gene for Drug Screening and Mechanistic Study in Endometrial Cancer

Expression of progesterone receptor (PR) is a favorable prognostic marker for multiple solid tumors. However, PR expression is reduced or lost in malignant tumors. Thus, monitoring and restoring functional PR expression is important in order to sensitize tumor cells to progesterone therapy in endometrial cancer. We developed stable PR reporter gene containing endometrial cancer cell lines monitoring the endogenous PR expression by inserting mCherry and hygromycin resistant gene at the endogenous PR gene locus by CRISPR/Cas9-mediated genome editing technique. This allows efficient, real-time monitoring of PR expression in its native epigenetic landscape. Reporter gene expression faithfully reflects and amplifies PR expression following treatment with drugs known to induce PR expression. Small molecular PR inducers have been identified from the FDA-approved 1018 drug library and tested for their ability to restore PR expression. Additionally, several candidate PR repressors have been identified by screening the genome-wide CRISPR knockout (GeCKO) library. This novel endogenous PR reporter gene system facilitates the discovery of a new treatment strategy to enhance PR expression and further sensitize progestin therapy in endometrial cancer. These tools provide a systematic, unbiased approach for monitoring target gene expression, allowing for novel drug discovery and mechanistic exploration.

Network Pharmacology Study and Experimental Validation of Yiqi Huayu Decoction Inducing Ferroptosis in Gastric Cancer

Objective

This study aimed to identify the mechanism of Yiqi Huayu Decoction (YQHY) induced ferroptosis in gastric cancer (GC) by using network pharmacology and experimental validation.

Methods

The targets of YQHY, ferroptosis-related targets, and targets related to GC were derived from databases. Following the protein–protein interaction (PPI) network, the hub targets for YQHY induced ferroptosis in GC were identified. Furthermore, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment were used to analyze the hub targets from a macro perspective. We verified the hub targets by molecular docking, GEPIA, HPA, and the cBioPortal database. Finally, we performed cell viability assays, quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, lipid peroxidation, and GSH assays to explore the mechanism of YQHY induced ferroptosis in GC.

Results

We identified the main active compounds and hub targets: Quercetin, DIBP, DBP, Mipax, Phaseol and TP53, ATM, SMAD4, PTGS2, and ACSL4. KEGG enrichment analyses indicated that the JAK2-STAT3 signaling pathway may be a significant pathway. Molecular docking results showed that the main active compounds had a good binding activity with the hub targets. The experimental results proved that YQHY could induce ferroptosis in AGS by increasing the MDA content and reducing the GSH content. qRT–PCR and Western blot results showed that YQHY can induce ferroptosis in GC by affecting the JAK2-STAT3 pathway and the expression of ACSL4.

Conclusions

This study indicated that YQHY can induce ferroptosis in GC by affecting the JAK2–STAT3 pathway and the expression of ACSL4, and induction of ferroptosis may be one of the possible mechanisms of YQHY’s anti-recurrence and metastasis of GC.

Interaction of microRNAs with sphingosine kinases, sphingosine-1 phosphate, and sphingosine-1 phosphate receptors in cancer

Sphingosine-1-phosphate (S1P), a pleiotropic lipid mediator, participates in various cellular processes during tumorigenesis, including cell proliferation, survival, drug resistance, metastasis, and angiogenesis. S1P is formed by two sphingosine kinases (SphKs), SphK1 and SphK2. The intracellularly produced S1P is delivered to the extracellular space by ATP-binding cassette (ABC) transporters and spinster homolog 2 (SPNS2), where it binds to five transmembrane G protein-coupled receptors to mediate its oncogenic functions (S1PR1-S1PR5). MicroRNAs (miRNAs) are small non-coding RNAs, 21-25 nucleotides in length, that play numerous crucial roles in cancer, such as tumor initiation, progression, apoptosis, metastasis, and angiogenesis via binding to the 3'-untranslated region (3'-UTR) of the target mRNA. There is growing evidence that various miRNAs modulate tumorigenesis by regulating the expression of SphKs, and S1P receptors. We have reviewed various roles of miRNAs, SphKs, S1P, and S1P receptors (S1PRs) in malignancies and how notable miRNAs like miR-101, miR-125b, miR-128, and miR-506, miR-1246, miR-21, miR-126, miR499a, miR20a-5p, miR-140-5p, miR-224, miR-137, miR-183-5p, miR-194, miR181b, miR136, and miR-675-3p, modulate S1P signaling. These tumorigenesis modulating miRNAs are involved in different cancers including breast, gastric, hepatocellular carcinoma, prostate, colorectal, cervical, ovarian, and lung cancer via cell proliferation, invasion, angiogenesis, apoptosis, metastasis, immune evasion, chemoresistance, and chemosensitivity. Therefore, understanding the interaction of SphKs, S1P, and S1P receptors with miRNAs in human malignancies will lead to better insights for miRNA-based cancer therapy.

Unique microRNA alterations in hepatocellular carcinomas arising either spontaneously or due to chronic exposure to Ginkgo biloba extract (GBE) in B6C3F1/N mice

Ginkgo biloba extract (GBE) is used in traditional Chinese medicine as a herbal supplement for improving memory. Exposure of B6C3F1/N mice to GBE in a 2-year National Toxicology Program (NTP) bioassay resulted in a dose-dependent increase in hepatocellular carcinomas (HCC). To identify key microRNAs that modulate GBE-induced hepatocarcinogenesis, we compared the global miRNA expression profiles in GBE-exposed HCC (GBE-HCC) and spontaneous HCC (SPNT-HCC) with age-matched vehicle control normal livers (CNTL) from B6C3F1/N mice. The number of differentially altered miRNAs in GBE-HCC and SPNT-HCC was 74 (52 up and 22 down) and 33 (15 up and 18 down), respectively. Among the uniquely differentially altered miRNAs in GBE-HCC, miR-31 and one of its predicted targets, Cdk1 were selected for functional validation. A potential miRNA response element (MRE) in the 3'-untranslated regions (3'-UTR) of Cdk1 mRNA was revealed by in silico analysis and confirmed by luciferase assays. In mouse hepatoma cell line HEPA-1 cells, we demonstrated an inverse correlation between miR-31 and CDK1 protein levels, but no change in Cdk1 mRNA levels, suggesting a post-transcriptional effect. Additionally, a set of miRNAs (miRs-411, 300, 127, 134, 409-3p, and 433-3p) that were altered in the GBE-HCCs were also altered in non-tumor liver samples from the 90-day GBE-exposed group compared to the vehicle control group, suggesting that some of these miRNAs could serve as potential biomarkers for GBE exposure or hepatocellular carcinogenesis. These data increase our understanding of miRNA-mediated epigenetic regulation of GBE-mediated hepatocellular carcinogenesis in B6C3F1/N mice.

MicroRNA-31 triggers G2/M cell cycle arrest, enhances the chemosensitivity and inhibits migration and invasion of human gastric cancer cells by downregulating the expression of zeste homolog 2 (ZH2)

Gastric cancer is the second most leading cause of cancer related mortality across the world over. Although the incidence of GC has declined to some extent but it is still the fourth highly diagnosed cancer across the world. GC generally remains undiagnosed till advanced stages due to unavailability of biomarkers and when diagnosed it becomes difficult to manage due to the lack of therapeutic targets and efficient chemotherapy. There are concrete evidences suggesting that miRNAs may prove important therapeutic targets for the treatment of devastating diseases such as cancer. The study was designed to investigate the tumor suppressive role of miR-31 via regulation of zeste homolog 2 (ZH2). It was found that miR-31 is significantly downregulated in GC cell lines. Overexpression of miR-31 causes significant (P < 0.05) decrease in the viability and colony formation via initiation of G2/M cell cycle arrest of the AGS cancer cells. Moreover, miR-31 overexpression also enhanced the chemosensitivity of miR-31 to the anticancer drug 5-fluorouracil. In silico analysis together with dual luciferase reporter assay indicated zeste homolog 2 (ZH2) to be the potential target of miR-31 in AGS cells. Investigation of ZH2 expression in GC cell lines showed it to be significantly (P < 0.05) upregulated. Nonetheless, overexpression of miR-31 in AGS cells resulted in the suppression of ZH2 expression. Additionally, silencing of ZH2 in the AGS cells also caused inhibition of AGS cell proliferation and colony formation via G2/M arrest. Moreover, overexpression of ZH2 could at least partially reverse the tumor suppressive effects of miR-31 indicating direct involvement of ZH2 in the miR-31 mediated inhibitory effects on AGS cell proliferation. Finally, miR-31 overexpression caused significant (P < 0.05) inhibition of the migration and invasion of the AGS gastric cancer cells. The overexpression of miR-31 also caused downregulation of mesenchymal markers (Vimentin and N-cadherin) and upregulation of epithelial marker (E-cadherin) protein expression was in AGS cells. It is therefore concluded that miR-31 acts as a tumor suppressor and may prove essential in the treatment of GC.

Rs4938723 Polymorphism Is Associated with Susceptibility to Hepatocellular Carcinoma Risk and Is a Protective Factor in Leukemia, Colorectal, and Esophageal Cancer

BACKGROUND Growing evidence indicates that a non-coding RNA named miR-34b/c plays crucial roles in carcinogenesis, and its common polymorphism, pri-miR-34b/c rs4938723, also participates in this process and is associated with cancer susceptibility. However, this association was previously undefined and ambiguous. Therefore, we carried out an updated analysis to evaluate this relationship between rs4938723 polymorphism and cancer susceptibility. MATERIAL AND METHODS PubMed, EMbase, Web of Science and Chinese language (WanFang, CNKI and VIP) databases were searched for relevant studies until Sep 10, 2018. Odds ratios and 95% confidence interval were applied to assess this relationship. RESULTS Thirty case-control studies were retrieved. No positive association was found in either the overall study population or in the subgroups, based on ethnicity, source of group, sex, smoking, and drinking status. The main results were observed in the stratified analysis subgroups in cancer type subgroup: rs4938723 polymorphism may be a protective factor in leukemia, colorectal cancer, and esophageal cancer; however, C-allele was a risk factor in carriers for hepatocellular carcinoma. Last but not the least, poor positive results were discovered in the age subgroup. CONCLUSIONS Current meta-analysis suggested that rs4938723 polymorphism was potentially associated with hepatocellular carcinoma risk, but this polymorphism had a decreased association for susceptibility to esophageal cancer, leukemia, and colorectal cancer. Furthermore, studies with larger sample sizes and including gene-gene or gene-environment interactions should be carried out to elucidate the role of rs4938723 polymorphism in cancer risk.

Functions and mechanisms of microRNA-31 in human cancers

MicroRNAs can exhibit opposite functions in different tumors. MiR-31 is a representative example as it can not only enhance tumor development and progression in pancreatic cancer, colorectal cancer and so on, but also inhibit tumorigenesis and induce apoptosis in ovarian cancer, prostate cancer and etc. The mechanism underlying its' pleiotropy remains unknown. Several recent studies that focused on the global gene expression changes caused by aberrant miR-31 provided information on the upstream and downstream events associated with deregulated miR-31. MiR-31 might interact with a number of signaling pathways including RAS/MARK, PI3K/AKT and RB/E2F to play its opposite functions. This review summarizes the target genes and pathways associated with miR-31 and examines the mechanisms underlying the function of miR-31. The resulting hypothesis is possible that the tissue-specific features of adenocarcinoma and squamous cell cancer and the positive feedback loop consists of miR-31 and its upstream and downstream may account for the diversity of miR-31 functions.

Association between Pri-miR-34b/c rs4938723 polymorphism and bladder cancer risk

Several studies examined the impact of miR-34b/c rs4938723 polymorphism and cancer risk, but the findings are inconsistent. However, no study has been conducted to inspect the impact of miR-34b/c polymorphism on bladder cancer. This study aimed to assess possible association between rs4938723 polymorphism and bladder cancer risk. This case-control study was done on 136 pathologically proven bladder cancer patients and 144 controls. Genotyping of Pri-miR-34b/c rs4938723 polymorphism was achieved by using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. Our findings did not show any statistically significant differences in genotype and allele frequencies between bladder cancer and controls. Larger sample sizes with diverse ethnicities are required to validate our findings.

MicroRNA31-NDRG3 regulation axes are essential for hepatocellular carcinoma survival and drug resistance

BACKGROUNDS

Hepatocellular carcinoma (HCC) is an epithelial cancer that originates from hepatocytes and it is the most common primary malignant tumor of the liver. Till now the prognosis of HCC patients is generally poor. The molecular mechanism giving rise to HCC development and recurrence is still largely unknown. MicroRNA-31 (miR-31) is among the most commonly altered microRNAs in human cancers, and alternations of miR-31 expression were reported to play pivotal roles in tumorigenesis and tumor progression.

METHODS

In this work, the primary biological function of miR-31 in HCC tumorigenesis was investigated.

RESULTS

Our data showed that overexpression of miR-31 induced markedly inhibition of HCC cell proliferation, migration in vitro and inhibited xenograft tumor growth in vivo. One target gene of miR-31, NDRG3, was also demonstrated indispensable for HCC cell survival. Furthermore, miR-31 and NDRG3 were both essential for HCC cell drug resistance in adriamycin.

CONCLUSIONS

We conclude that miR-31 is a crucial regulator in hepatocellular carcinoma, miR-31 and its target gene NDRG3 may be potential therapeutic targets for HCC treatment in the future.

Circulating miR-31 as an effective biomarker for detection and prognosis of human cancer: a meta-analysis

PURPOSE

Circulating miR-31 was found to be associated with cancers detection and prognosis. The present meta-analysis aimed to explore the effect of circulating miR-31 on cancer detection and prognosis.

METHOD

The studies were accessed using multiple databases. RevMan5.3, Meta-DiSc 1.4, and STATA14.0 were used to estimate the pooled effects, heterogeneity among studies, and publication bias.

RESULTS

A total of 14 studies with 1397 cancer patients and 1039 controls were included. For the 12 prognostic tests, the adjusted pooled-AUC was 0.79 (95% CI: 0.73-0.86) as the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odd ratio (DOR) from 10 tests was 0.79 (95% CI: 0.76-0.82), 0.79 (95% CI: 0.76-0.82), 3.81 (95% CI: 2.90-5.01), 0.26 (95% CI: 0.20-0.35), and 16.81 (95% CI: 9.67-29.25), respectively. For the 5 prognosis analyses, the pooled HR (hazard ratio) of overall survival (OS) was 1.55 (95% CI 1.30-1.86) for high versus low circulating miR-31 expression. However, high expression of circulating miR-31 did not significantly increase the risk of poor differentiation (pooled OR=1.39, 95% CI: 0.56-3.47) and LNM (pooled OR=3.46, 95% CI: 0.96-12.42) in lung cancer.

CONCLUSION

Circulating miR-31 is an effective biomarker and could be used as a component of miRs signature for cancer detection and prognosis surveillance.

p38 and JNK pathways control E-selectin-dependent extravasation of colon cancer cells by modulating miR-31 transcription

Extravasation of circulating cancer cells is a key event of metastatic dissemination that is initiated by the adhesion of cancer cells to vascular endothelial cells. It requires the interaction between adhesion receptors such as E-selectin present on endothelial cells and their ligands on cancer cells. Notably, E-selectin influences the metastatic potential of breast, bladder, gastric, pancreatic, and colorectal carcinoma as well as of leukemia and lymphoma. Here, we show that E-selectin expression induced by the pro-inflammatory cytokine IL-1β is directly and negatively regulated by miR-31. The transcription of miR-31 is activated by IL-1β. This activation depends on p38 and JNK MAP kinases, and their downstream transcription factors GATA2, c-Fos and c-Jun. The miR-31-mediated repression of E-selectin impairs the metastatic potential of colon cancer cells by decreasing their adhesion to, and migration through, the endothelium. These results highlight for the first time that microRNA mediates E-selectin-dependent extravasation of colon cancer cells.

MicroRNA-31 functions as a tumor suppressor and increases sensitivity to mitomycin-C in urothelial bladder cancer by targeting integrin α5

Urothelial bladder cancer (UBC) is a common genitourinary malignancy. MiR-31, a well-identified miRNA, exhibits diverse properties in different cancers. However, the specific functions and mechanisms of miR-31 in UBC have not been investigated. In this study, tumor samples, especially invasive UBC, showed significantly reduced level of miR-31, as compared with normal urothelium. Prognostic analysis using the EORTC model showed that down-regulation of miR-31 correlated with higher risks of recurrence and progression in noninvasive UBC cases. Remarkably, overexpression of miR-31 mimics in UBC cell lines inhibited cell proliferation, migration and invasion. Integrin α5 (ITGA5), an integrin family member, was subsequently identified as a direct target of miR-31 in UBC cells. When treated with mitomycin-C (MMC), miR-31-expressing UBC cells displayed lower survival and higher apoptotic rates, and deactivated Akt and ERK. These effects arising from miR-31 overexpression were abrogated by ITGA5 restoration. Furthermore, miR-31 markedly inhibited tumor growth and increased the effectiveness of MMC in UBC xenografts. In summary, our data suggest that miR-31 is a prognostic predictor and can serve as a potential therapeutic target of UBC.

The relationship between microRNAs and the STAT3-related signaling pathway in cancer

MicroRNAs are non-coding RNAs that regulate gene expression by targeting messenger RNA molecules in 3' untranslated region. Mounting evidence indicates that microRNAs regulate several factors to influence various biological activities that are related to carcinogenesis, including signal transducer and activator of transcription 3, which is a transcription factor that also acts as an oncogene. MicroRNAs influence signal transducer and activator of transcription 3 either by directly targeting or via other pathway components upstream or downstream of signal transducer and activator of transcription 3 such as Janus kinases, members of the suppressor of cytokine signaling family, and other genes that regulate cell proliferation, apoptosis, migration, invasion, and epithelial-mesenchymal transition. However, signal transducer and activator of transcription 3 activation changes the pattern of expression of microRNAs and mediates tumorigenesis. Moreover, the relationship between signal transducer and activator of transcription 3 and microRNAs varies among different kinds of cancers. A specific microRNA may act as an oncogene or tumor suppressor in different cancers, and microRNAs also directly or indirectly regulate signal transducer and activator of transcription 3 via pathways in the same cancers. In this review, we focus on the reciprocal regulation and roles of microRNAs and signal transducer and activator of transcription 3 in cancer, as well as describe current research progress on this relationship. A better understanding of this relationship may facilitate in the identification of targets for clinical therapeutics.

MicroRNA-31 inhibits RhoA-mediated tumor invasion and chemotherapy resistance in MKN-45 gastric adenocarcinoma cells

microRNAs are small single-stranded non-coding RNA molecules which modify gene expression by silencing potential target genes. The aberrant expression of RhoA, a small GTPase protein of Rho family, is involved in gastric cancer tumorigenesis. Since miR-31 is a pleomorphic molecule, we evaluated the miR-31/RhoA axis in inducing the malignant phenotype of gastric cancer cells MKN-45. Also, the clinicopathological significance of RhoA was investigated in a well-defined collection of gastric carcinomas which were embedded in tissue microarray blocks. Induction of miR-31 in MKN-45 followed by suppression of RhoA expression resulted in increased sensitivity to 5-fluorouracil, inhibition of cell proliferation, and invasion compared to the control groups. Immunohistochemical analysis in gastric adenocarcinoma patients' samples showed significantly higher expression of RhoA in diffuse versus intestinal subtype tumors ( P = 0.009), poorly differentiated versus well and moderately differentiated tumors ( P = 0.03) and the presence of vascular invasion versus the absence of vascular invasion ( P = 0.04). Our findings suggest a critical role for miR-31, as a tumor suppressor gene, in gastric cancer tumorigenesis by targeting the RhoA. Impact statement Gastric cancer ranks as the third leading cause of cancer-associated deaths worldwide. The RhoA gene encodes a small GTPase protein of Rho family (RhoA) that its dysregulation is associated with cell motility and invasion. A strong line of evidence supports the regulation of RhoA by a number of miRs, including miR-31 in tumors. Our findings revealed that miR-31 is involved in gastric cancer tumorigenesis as a tumor suppressor gene. Through down-regulation of RhoA, miR-31 decreased cell proliferation, migration, and invasion in gastric cancer cells. In addition, induction of miR-31 increased sensitivity to 5-FU; thus, increasing its tissue concentrations could be a potential target for treatment of gastric cancer in the future.

Identification of aminosulfonylarylisoxazole as microRNA-31 regulators

The discovery of small-molecule regulators of microRNAs remains challenging, but a few have been reported. Herein, we describe small-molecule inhibitors of miR-31, a tumor-associated microRNA (miRNA), identified by high-throughput screening using a cell-based reporter assay. Aminosulfonylarylisoxazole compounds exhibited higher specificity for miR-31 than for six other miRNAs, i.e., miR-15a, miR-16, miR-21, miR-92a-1, miR-146a, and miR-155, and increased the expression of miR-31 target genes. The down-regulation of mature miR-31 was observed, while its precursor form increased following treatment with the compounds. Thus, the compounds may target the processing of pre-miR-31 into mature miR-31 and thereby inhibit the production of mature miR-31.

Increased expression of microRNA-31-5p inhibits cell proliferation, migration, and invasion via regulating Sp1 transcription factor in HepG2 hepatocellular carcinoma cell line

Accumulating evidence has suggested that microRNA-31-5p (miR-31-5p) is dysfunctional in hepatocellular carcinoma (HCC). However, the molecular mechanism of HCC remains unclear. In this study, we investigated the role of miR-31-5p in tumor formation and development of HCC. The expression of miR-31-5p was detected in HCC tissues, corresponding adjacent tissues, normal liver tissues, and HCC cell lines. miR-31-5p mimics and an inhibitor were transfected into HepG2 cells to assess the effects of miR-31-5p on cell proliferation, apoptosis, cell cycle, migration, and invasion assays. Western blotting was used to detect the expression of Sp1 transcription factor (SP1), cyclin D1, and survivin in transfected HCC cells and control cells. The expression of miR-31-5p was significantly decreased in HCC cells and HCC tissues. Overexpression of miR-31-5p inhibited HCC cell growth, migration, and invasion. Overexpression of miR-31-5p reduced the expression of SP1 and cyclin D1, and knockdown of SP1 decreased cyclin D1 expression. The dual luciferase assay showed that miR-31-5p directly targeted SP1 in HepG2. Together, the results suggested that miR-31-5p acted as a tumor suppressor to regulate SP1, and that miR-31-5p could be used as a therapeutic target for the treatment of HCC.

Down-regulated miRs specifically correlate with non-cardial gastric cancers and Lauren's classification system

BACKGROUND AND OBJECTIVES

Gastric cancers are usually characterized using Lauren's classification into intestinal and diffuse types. We previously documented the down-modulation of miR31, miR148a, miR204, and miR375 in gastric cancers. We aimed this manuscript to investigate these miRs with the end-points of diagnosis, Lauren's classification and prognosis.

METHODS

A total of 117 resected non-cardial adenocarcinomas were evaluated for miRs' expressions. The performance of miRs' expressions for cancer diagnosis was tested using ROC curves. Logistic regression was conducted with the end-point of Lauren's classification. Kaplan-Meier and Cox analyses were performed for OS, DFS, and DSS. miRs' targets were reviewed using PRISMA method and BCL-2 was further investigated in cell lines.

RESULTS

ROC curves documented that miRs' down-modulation was significant in differentiating cancer versus normal tissues. Diffuse type cancers were associated with female sex, young age, and miR375 higher expression. We confirmed BCL-2 as a miR204 target. However, survival analyses confirmed the pathologic criteria (advanced stages, LNR, and low LNH) as the significant variables correlated to worse prognosis.

CONCLUSIONS

The down-modulation of miR31, miR148a, miR204, and miR375 is significantly associated with non-cardial gastric cancers and miR375 is specifically linked to Lauren's classification. Nevertheless, standard pathological features display as the independent variables associated with worse prognosis.

MiR-31 Regulates Rho-Associated Kinase-Myosin Light Chain (ROCK-MLC) Pathway and Inhibits Gastric Cancer Invasion: Roles of RhoA

Background

This study evaluated how the expression of miR-31 can be used to detect gastric cancer (GC) to help illuminate the role of miR-31 and RhoA in GC cells.

Material/Methods

We carried out our experiments using tissue specimens from 70 GC patients. The relative expression of miR-31 and RhoA mRNA in tissues and cells was detected by RT-PCR. The expression level of RhoA protein was detected by immunohistochemistry. GC cell line BGC-823 was transfected with six groups of vectors: blank group, NC (negative control) group, miR-31 mimics group, miR-31 mimics + RhoA group, miR-31 mimics + ROCK group, and miR-31 mimics + MLCK agonist group. AGS cells were also transfected with six groups of vectors: blank group, NC group, miR-31 inhibitor group, miR-31 inhibitor + RhoA siRNA group, miR-31 inhibitor + ROCK siRNA group, and miR-31 inhibitor + MLCK inhibitor group. Transwell assay was performed to detect the invasion and migration of cells. The protein expression in different transfected groups was detected using Western blotting.

Results

GC tissues exhibited significantly lower levels of miR-31 expression compared to pericarcinous tissues (p<0.01). Moreover, a significantly higher expression of RhoA in GC tissues was observed (p<0.05). MiR-31 inhibited RhoA expression by binding to 3′UTR of mRNA, whereas miR-31 mimics significantly decreased the number of invaded and migrated cells (p<0.05). The activation of RhoA, ROCK, and phosphorylation of MLC remarkably exacerbate the invasion and migration ability of GC cells (p<0.05).

Conclusions

We found miR-31 could downregulate the ROCK/MLC pathway by inhibiting the expression of RhoA in order to suppress the invasion and migration of GC cells.

Klf4 inhibits tumor growth and metastasis by targeting microRNA-31 in human hepatocellular carcinoma

MicroRNAs (miRNAs or miRs) are short, endogenous non-coding RNA molecules, demonstrating abnormal expression in cancer initiation and progression. In this study, we profiled 18 differentially regulated miRNAs, including miRNA-31, using miRNA array. Kruppel (or Krüppel)-like factor 4 (Klf4) is a transcription factor and putative tumor suppressor. Both were found to be significantly downregulated in liver cancer tissues and cells. However, little is known about the correlation between Klf4 and miRNA-31 in hepatocellular carcinoma (HCC). The mRNA expression of Klf4 was decreased and inversely associated with the clinical stage, T classification and hepatitis B in patients with HCC, while the expression of miR-31 was lower (r=0.326, P=0.018). Using cell counting kit 8 (CCK8) and Transwell migration assays, we found that Klf4 and miR-31 inhibited the proliferation and metastasis of liver cancer cells. Moreover, we demonstrated that Klf4 directly binds to the promoter of miR-31 and activates its transcription. In vitro experiments confirmed that Klf4 regulated miR-31 and thereby inhibited HCC cell growth and metastasis. Taken together, our findings indicate that Klf4 directly regulates miR-31 in HCC. Thus, miR-31 may serve as a potential diagnostic marker and therapeutic target in HCC.

Pri-miR-34b/c rs4938723 polymorphism is associated with the risk of childhood acute lymphoblastic leukemia

MicroRNAs (miRNAs), small noncoding regulatory RNAs, are key regulators of gene expression. The impact of Pri-miR-34b/c rs4938723 variant on development of various cancers is still controversial. In the present study, we examined whether a rs4938723 variant located at the promoter region of Pri-miR-34b/c is associated with childhood ALL. A total of 110 children with acute lymphoblastic leukemia (ALL) and 120 healthy children were recruited to participate in this study. The rs4938723 variant was genotyped by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. The rs4938723 variant decreased the risk of ALL in heterozygous (TC vs OR = 0.48, 95% CI = 0.28-0.84, p = 0.012, TC vs TT) and overdominant (OR = 0.51, 95% CI = 0.30-0.89, p = 0.0.020, TC vs TT + CC): OR = 1.32, 95% CI = 0.67-2.59, p = 0.498; C vs T: OR = 0.99, 95% CI = 0.75-1.31, p = 0.986) inheritance models tested. The C allele significantly decreased the risk of childhood ALL compared to T allele (OR = 0.52, 95% CI = 0.33-0.83, p = 0.006). Our findings proposed an association between Pri-miR-34 b/c rs4938723 variant and risk of childhood ALL development in a sample of Iranian population.

Decreased expression of LncRNA MIR31HG in human bladder cancer

OBJECTIVE

In this study, we examined the relationships between the expression level of long non-coding RNA MIR31HG in bladder cancer and the clinical characteristics.

METHODS

A total of 55 tissue samples from patients with bladder cancer were collected, and the lncRNA MIR31HG levels in cancer, paired non-cancer tissues and BC cell lines were detected by real-time quantitative RT-PCR (qRT-PCR). The relationships between MIR31HG level and the clinical characteristics were evaluated.

RESULTS

MIR31HG expression was remarkably decreased in bladder cancer tissues compared with adjacent noncancerous tissues (P < 0.05). MIR31HG expression was also significantly down-regulated in four bladder cancer cell lines (P < 0.001). Clinicopathologic analysis revealed that MIR31HG expression was negatively associated with TNM stage (P = 0.010), but not with other clinicopathological characteristics.

CONCLUSIONS

These findings revealed that MIR31HG may function as a cancer-suppressor gene to participate in the bladder cancer carcinogenesis and development.

Evaluation of the pri-miR-34b/c rs4938723 polymorphism and its association with breast cancer risk

MicroRNAs (miRNAs or miRs) are a family of small non-coding RNAs that function as oncogenes or tumor suppressor genes. Recent evidence suggests that the pri-miR-34b/c rs4938723 variant is associated with the development of cancer. At present, there is an inconsistent association between the single-nucleotide polymorphism in pri-miR-34b/c and cancer in the limited studies. The present study is a case-control investigation, with 263 breast cancer (BC) patients and 221 control women, which examined the potential association of the pri-miR-34b/c rs4938723 polymorphisms with BC susceptibility. The polymorphisms were genotyped by the polymerase chain reaction restriction fragment length polymorphism method. No significant association between the pri-miR-34b/c rs4938723 variant and BC was identified [TC vs. TT: Odds ratio (OR), 0.87; 95% confidence interval (CI), 0.60-1.26; P=0.506; CC vs. TT: OR, 1.22; 95% CI, 0.61-2.47; P=0.600; TC+CC vs. TT: OR, 0.91; 95% CI, 0.64-1.31; P=0.648; CC vs. TT+TC: OR, 1.32; 95% CI, 0.67-2.59; P=0.498; C vs. T: OR, 0.99; 95% CI, 0.75-1.31; P=0.986]. However, a significant association was observed between the pri-miR-34b/c rs4938723 genotypes and clinicopathological characteristics, such a grade, progesterone receptor and human epidermal growth factor receptor 2 status were observed (P<0.05). These findings suggest that the pri-miR-34b/c rs4938723 variant may not be a risk factor for the development of BC.

NUDT2 Disruption Elevates Diadenosine Tetraphosphate (Ap4A) and Down-Regulates Immune Response and Cancer Promotion Genes

Regulation of gene expression is one of several roles proposed for the stress-induced nucleotide diadenosine tetraphosphate (Ap₄A). We have examined this directly by a comparative RNA-Seq analysis of KBM-7 chronic myelogenous leukemia cells and KBM-7 cells in which the NUDT2 Ap₄A hydrolase gene had been disrupted (NuKO cells), causing a 175-fold increase in intracellular Ap₄A. 6,288 differentially expressed genes were identified with P < 0.05. Of these, 980 were up-regulated and 705 down-regulated in NuKO cells with a fold-change ≥ 2. Ingenuity^® Pathway Analysis (IPA^®) was used to assign these genes to known canonical pathways and functional networks. Pathways associated with interferon responses, pattern recognition receptors and inflammation scored highly in the down-regulated set of genes while functions associated with MHC class II antigens were prominent among the up-regulated genes, which otherwise showed little organization into major functional gene sets. Tryptophan catabolism was also strongly down-regulated as were numerous genes known to be involved in tumor promotion in other systems, with roles in the epithelial-mesenchymal transition, proliferation, invasion and metastasis. Conversely, some pro-apoptotic genes were up-regulated. Major upstream factors predicted by IPA^® for gene down-regulation included NFκB, STAT1/2, IRF3/4 and SP1 but no major factors controlling gene up-regulation were identified. Potential mechanisms for gene regulation mediated by Ap₄A and/or NUDT2 disruption include binding of Ap₄A to the HINT1 co-repressor, autocrine activation of purinoceptors by Ap₄A, chromatin remodeling, effects of NUDT2 loss on transcript stability, and inhibition of ATP-dependent regulatory factors such as protein kinases by Ap₄A. Existing evidence favors the last of these as the most probable mechanism. Regardless, our results suggest that the NUDT2 protein could be a novel cancer chemotherapeutic target, with its inhibition potentially exerting strong anti-tumor effects via multiple pathways involving metastasis, invasion, immunosuppression and apoptosis.