Primary analysis and screening of microRNAs in gastric cancer side population cells

MicroRNA-34 and gastrointestinal cancers: a player with big functions

It is commonly assumed that gastrointestinal cancer is the most common form of cancer across the globe and is the leading contributor to cancer-related death. The intricate mechanisms underlying the growth of GI cancers have been identified. It is worth mentioning that both non-coding RNAs (ncRNAs) and certain types of RNA, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs), can have considerable impact on the development of gastrointestinal (GI) cancers. As a tumour suppressor, in the group of short non-coding regulatory RNAs is miR-34a. miR-34a silences multiple proto-oncogenes at the post-transcriptional stage by targeting them, which inhibits all physiologically relevant cell proliferation pathways. However, it has been discovered that deregulation of miR-34a plays important roles in the growth of tumors and the development of cancer, including invasion, metastasis, and the tumor-associated epithelial-mesenchymal transition (EMT). Further understanding of miR-34a's molecular pathways in cancer is also necessary for the development of precise diagnoses and effective treatments. We outlined the most recent research on miR-34a functions in GI cancers in this review. Additionally, we emphasize the significance of exosomal miR-34 in gastrointestinal cancers.

MicroRNA-324-5p-CUEDC2 Axis Mediates Gain-of-Function Mutant p53-Driven Cancer Stemness

Regulation of cancer stemness has recently emerged as a new gain-of-function (GOF) property of mutant p53. In this study, we identify miR-324-5p as a critical epigenetic regulator of cancer stemness and demonstrate its role in mediating GOF-mutant p53-driven stemness phenotypes. We report that miR-324-5p is upregulated in human cancer cell lines and non-small cell lung carcinoma (NSCLC) tumors carrying TP53 GOF mutations. Mechanistically, we show that GOF mutant p53 upregulates miR-324-5p expression via c-Myc, an oncogenic transcription factor in cancer cells. Our experimental results suggest that miR-324-5p-induced CSC phenotypes stem from the downregulation of CUEDC2, a downstream target gene of miR-324-5p. Accordingly, CUEDC2 complementation diminishes elevated CSC marker expression in miR-324-5p-overexpressing cancer cells. We further demonstrate that mutant p53 cancer cells maintain a low level of CUEDC2 that is rescued upon miR-324-5p inhibition. Importantly, we identify CUEDC2 downregulation as a novel characteristic feature of TP53-mutated human cancers. We show that activation of NF-κB due to downregulation of CUEDC2 by miR-324-5p imparts stemness in GOF mutant p53 cancer cells. Finally, we provide evidence that TP53 mutations coupled with high miR-324-5p expression predict poor prognosis in patients with lung adenocarcinoma. Thus, our study delineates an altered miR-324-5p-CUEDC2-NF-κB pathway as a novel regulator of GOF mutant p53-driven cancer stemness. IMPLICATIONS: Our findings implicate miRNA-324-5p as a novel epigenetic modifier of human cancer stemness.

Silencing of microRNA-3175 represses cell proliferation and invasion in prostate cancer by targeting the potential tumor-suppressor SCN4B

MicroRNA-3175 (miR-3175) expression is upregulated in prostate cancer, but its roles and the underlying mechanisms in prostate cancer cell growth and invasion need to be elucidated. This study aimed to uncover the roles of miR-3175 in regulating cell growth and migration, as well as the expression of its predicted target gene cardiac sodium channel β4-subunit gene (SCN4B). Real-time quantitative PCR (RT-qPCR) and/or western blotting techniques were used to measure miR-3175 and SCN4B expression levels in prostate cancer cells. Inhibitor or mimics transfections were used to overexpress or silence miR-3175 in prostate cancer cells. MTT and Edu assays were applied to assess cell viability. Scratch assay and transwell chambers were used to examine cell migration and invasion abilities. The interaction between miR-3175 and SCN4B was determined by means of luciferase gene reporter, RT-qPCR, and western blotting assays. The results showed that miR-3175 expression was increased and SCN4B expression was decreased in prostate cancer cell lines as compared with normal human prostatic epithelial cells. Compared with the control group, knockdown of miR-3175 resulted in strong inhibitions of cell growth, migration, invasion, and N-cadherin expression, together with an increase in E-cadherin expression. In addition, knockdown of miR-3175 dramatically increased the luciferase activity of the luciferase vector of SCN4B, and increased SCN4B expression. Together, this study illustrated that downregulation of miR-3175 repressed the proliferation and invasion of prostate cancer cells, which might be induced by SCN4B downregulation.

Integrated analysis and knockdown of RAB23 indicate the role of RAB23 in gastric adenocarcinoma

Background

The present study aimed to identify key differentially expressed genes (DEGs) and miRNAs (DEmiRNAs) in gastric adenocarcinoma.

Methods

We performed integrated analysis to determine DEGs and DEmiRNAs of gastric adenocarcinoma based on the GEO database. A DEmiRNA-target interaction network was established. GO and KEGG pathway enrichment analyses were utilized. Then, MKN45 cells were transfected with shRNA-RAB23 to knock down the expression of RAB23. CCK-8, transwell and flow cytometry assays were utilized to measure the capacities for cell proliferation, migration and apoptosis, and the apoptosis-related gene and protein levels were measured by using polymerase chain reaction (PCR) and Western blot, respectively. Colocalization analysis of Snc1 with the vesicular protein VAMP3 and the endoplasmic reticulum protein Calnexin was performed to assess the influence of RAB23 on vesicle transport. Finally, we performed metabolomic analysis by using gas chromatography mass spectrometry (GC-MS).

Results

We performed MMIA of gastric adenocarcinoma based on two miRNA datasets and two mRNA datasets. A total of 4,586 DEmRNAs and 30 DEmiRNAs were obtained. The DEmRNAs of gastric adenocarcinoma were significantly enriched in PI3K/Akt signaling. We identified three interactions, hsa-miR-23a-3p-PTPN4, hsa-miR-20b-5p (hsa-miR-130a-3p)-TNFRSF10B, and hsa-miR-130a-3p (hsa-miR-363-3p)-RAB23, that may be related to the pathogenesis of gastric adenocarcinoma. The growth of MKN45 cells was inhibited by RAB23 knockdown via shRNA-RAB23 transfection. Metabolic analysis of three groups revealed a number of significantly altered metabolites, including glycerol, niacinamide, and nonadecanoic acid methylester.

Conclusions

RAB23 might be a target gene of hsa-miR-130a-3p and hsa-miR-363-3p. In gastric adenocarcinoma cells, knockdown of RAB23 inhibited cell proliferation, migration, and invasion and increased apoptosis by downregulating the PI3K/Akt pathway.

MiR-3175 promotes epithelial-mesenchymal transition by targeting Smad7 in human conjunctiva and pterygium

MicroRNAs (miRNAs) are involved in the post-transcriptional regulation of mRNAs. However, the function of miRNAs is unclear in epithelial-mesenchymal transition (EMT) of pterygium, a disease characterized by abnormal fibrovascular proliferation and invasion on the ocular surface. Since MiR-3175 is upregulated in pterygium tissues compared to normal conjunctival tissues, in this study, we investigated the role of MiR-3175 in EMT of a cultured human conjunctival epithelium cell line (CCL) and further validated the findings in pterygium tissues from patients. Our study demonstrates that MiR-3175 promotes proliferation, migration, invasion, and EMT of CCL cells by directly inhibiting Smad7. In conclusion, our data suggested that the MiR-3175-Smad7 axis may play a critical role in pathogenesis and development of pterygium.

Up-Regulation of MiR-1915 Inhibits Proliferation, Invasion, and Migration of Helicobacter pylori-Infected Gastric Cancer Cells via Targeting RAGE

PURPOSE

Helicobacter pylori (HP)-infected gastric cancer (GC) is known to be a fatal malignant tumor, but the molecular mechanisms underlying its proliferation, invasion, and migration remain far from being completely understood. Our aim in this study was to explore miR-1915 expression and its molecular mechanisms in regulating proliferation, invasion, and migration of HP-infected GC cells.

MATERIALS AND METHODS

Quantitative real-time PCR and western blot analysis were performed to determine miR-1915 and receptor for advanced glycation end product (RAGE) expression in HP-infected GC tissues and gastritis tissues, as well as human gastric mucosal cell line GES-1 and human GC cell lines SGC-7901 and MKN45. CCK8 assay and transwell assay were performed to detect the proliferation, invasion, and migration capabilities. MiR-1915 mimics and miR-1915 inhibitor were transfected into GC cells to determine the target relationship between miR-1915 and RAGE.

RESULTS

MiR-1915 was under-expressed, while RAGE was over-expressed in HP-infected GC tissues and GC cells. Over-expressed miR-1915 could attenuate cellular proliferation, invasion, and migration capacities. RAGE was confirmed to be the target gene of miR-1915 by bioinformatics analysis and luciferase reporter assay. Moreover, HP-infected GC cellular proliferation, invasion, and migration were inhibited after treatment with pcDNA-RAGE.

CONCLUSION

MiR-1915 exerted tumor-suppressive effects on cellular proliferation, invasion, and migration of HP-infected GC cells via targeting RAGE, which provided an innovative target candidate for treatment of HP-infected GC.

Gastric Cancer Stem Cells: Mechanisms and Therapeutic Approaches

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide. GC stem-like cells (GCSCs), with unlimited self-renewal, differentiation, and tumor-regenerating capacities, contribute significantly to the refractory features of GC and have gained increasing attention for their role in GC drug resistance, relapse, and metastasis. Therapies targeting GCSCs seem to be one of the most promising methods to improve the outcomes of GC patients. Extensive investigations have attempted to outline the regulatory mechanisms in GCSCs and to develop GCSCs-targeting therapies with which to diminish GC drug resistance, metastasis and relapse. To the best of our knowledge, there is a lack of reviews summarizing these studies. In this review, we systematically recapitulated findings regarding the regulatory mechanisms of GCSCs, as well as therapies that target GCSCs, hoping to support the development of prognostic biomarkers and GCSCs-targeting anticancer therapies in GC.

MiR-324-5p reduces viability and induces apoptosis in gastric cancer cells through modulating TSPAN8

OBJECTIVES

The purpose of this study was to further clarify the role and underlying mechanism of miR-324-5p in gastric cancer.

METHODS

The expressions of miR-324-5p and TSPAN8 as determined by qRT-PCR or Western blot were compared between the gastric cancer tissues and normal tissues. Human gastric cancer cell line SGC-7901 was cultured and transfected with miR-324-5p mimic/inhibitor or pcDNA-TSPAN8. The cell survival was assessed by the cell viability and apoptosis. Luciferase reporter gene assays were performed to explore the interaction between miR-324-5p and TSPAN8 in SGC-7901 cells.

KEY FINDINGS

MiR-324-5p was decreased in human gastric carcinoma tissues (n = 33), but TSPAN8 protein expression was increased in the gastric carcinoma tissues (n = 33). Moreover, miR-324-5p inhibited the viability and induced the apoptosis of gastric cancer cells in vitro. TSPAN8 is a functional target of miR-324-5p in gastric cancer. MiR-324-5p was further confirmed to reduce gastric cancer cell viability and induce apoptosis via downregulating TSPAN8 in SGC-7901 cells in vitro. Additionally, miR-324-5p overexpression markedly inhibited the tumorigenesis of gastric cancer cells in vivo, as shown by the smaller tumour volume compared with the control.

CONCLUSIONS

This study suggested a novel, probable mechanism of miR-324-5p in gastric cancer context and revealed that miR-324-5p inhibited gastric cancer cell survival by targeting TSPAN8.

Colorectal adenoma and carcinoma specific miRNA profiles in biopsy and their expression in plasma specimens

BACKGROUND

MiRNA expression markers are well characterized in colorectal cancer (CRC), but less is known about miRNA expression profiles in colorectal adenomas. Genome-wide miRNA and mRNA expression analyses were conducted through the colorectal adenoma dysplasia sequence. Furthermore, analysis of the expression levels of miRNAs in matched plasma samples was performed, focusing on biomarker candidates; miRNA and mRNA expression analyses were performed on colorectal biopsies and plasma samples (20 normals; 11 tubular and 9 tubulovillous adenomas; 20 colorectal carcinomas) by miRNA 3.0 and Human Transcriptome Array (Affymetrix) and validated by RT-qPCR. Microarray data were analyzed using Expression Console and mRNA targets were predicted using miRWALK 2.0.

RESULTS

Based on microarray analysis, 447 miRNAs were expressed in tissue and 320 in plasma. Twelve were upregulated (miR-31, 8-fold p < 0.001) and 11 were downregulated (miR-10b 3-fold p < 0.001) in neoplastic lesions compared to normal group. Eleven miRNAs showed altered expression between adenoma subtypes (miR-183 2.8-fold change, p < 0.007). Expression level of 24 miRNAs differed between adenoma and CRC groups (including miR-196a, 3.5-fold). Three miRNAs (miR-31, miR-4506, miR-452*) were differentially expressed in adenoma compared to normal both in tissue and plasma samples. miRNA expression data were confirmed by RT-PCR both in plasma and matched tissue samples.

CONCLUSIONS

MiRNAs showed characteristic expression changes during CRC development in tissue. miRNAs were also presented in plasma and positively correlated with matched tissue expression levels. The identified miRNA expression changes could be verified RT-PCR methods facilitating routine application.

Role of competing endogenous RNAs in development of gastric cancer

Gastric cancer is one of the most common digestive system tumors and the second cause of malignancy related death, and it is caused by multiple factors such as genetic susceptibility, environment and living habits. It is reported that members of competitive endogenous RNAs, including microRNAs and long non-coding RNAs, play an important role in gastric cancer development. This article reviews the role of competing endogenous RNAs in the development of gastric cancer.

HOXB1 Is a Tumor Suppressor Gene Regulated by miR-3175 in Glioma

The HOXB1 gene plays a critical role as an oncogene in diverse tumors. However, the functional role of HOXB1 and the mechanism regulating HOXB1 expression in glioma are not fully understood. A preliminary bioinformatics analysis showed that HOXB1 is ectopically expressed in glioma, and that HOXB1 is a possible target of miR-3175. In this study, we investigated the function of HOXB1 and the relationship between HOXB1 and miR-3175 in glioma. We show that HOXB1 expression is significantly downregulated in glioma tissues and cell lines, and that its expression may be closely associated with the degree of malignancy. Reduced HOXB1 expression promoted the proliferation and invasion of glioma cells, and inhibited their apoptosis in vitro, and the downregulation of HOXB1 was also associated with worse survival in glioma patients. More importantly, HOXB1 was shown experimentally to be a direct target of miR-3175 in this study. The downregulated expression of miR-3175 inhibited cell proliferation and invasion, and promoted apoptosis in glioma. The oncogenicity induced by low HOXB1 expression was prevented by an miR-3175 inhibitor in glioma cells. Our results suggest that HOXB1 functions as a tumor suppressor, regulated by miR-3175 in glioma. These results clarify the pathogenesis of glioma and offer a potential target for its treatment.