Targeting miR-375 in gastric cancer

Investigations into the impact of non-coding RNA on the sensitivity of gastric cancer to radiotherapy

Non-coding RNAs (ncRNAs) are a newly discovered functional RNA different from messenger RNA, which can participate in regulating the occurrence and development of tumors. More and more research results show that ncRNAs can participate in the regulation of gastric cancer (GC) radiotherapy response, and its mechanism may be related to its effect on DNA damage repair, gastric cancer cell stemness, cell apoptosis, activation of epidermal growth factor receptor signaling pathway, etc. This article summarizes the relevant mechanisms of ncRNAs regulating the response to radiotherapy in gastric cancer, which will be directly important for the introduction of ncRNAs particularly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) into clinical medicine as biomarkers and therapeutic targets.

Targeted microRNA Profiling in Gastric Cancer with Clinical Assessement

Although several microRNAs (miRNAs) have been associated with gastric cancer there is still the need for identification of stable and validated biomarkers. The purpose of this study was to determine the alterations of a specific set of miRNA levels in gastric adenocarcinoma tissues to identify and validate gastric cancer-specific miRNAs using paired normal and tumor samples in an independent patient cohort. Gastric adenocarcinoma and normal stomach tissue samples of 20 patients who underwent surgery for gastric cancer were studied. The miRNA expression profiling was performed for eight miRNAs in a total of 40 tissue samples using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Six out of these eight miRNAs, namely, miR-375-3p, hsamiR-129-5p, miR-196a-5p, miR-376c-3p, miR-34c-5p and miR-767-5p, were significantly underexpressed in malignant tissues of our cohort. Furthermore, the expression of miR-662 although not significantly different between normal and tumor tissues, was inversely associated with age (r = −0.440, p = 0.049). The levels of miR-129-3p and miR34c-5p were correlated with an increase in the number of metastatic lymph nodes (r = 0.470, p = 0.036; r = 0.510, p = 0.020), while and miR-376c-3p levels were negatively associated with smoking (p = 0.043). In addition, we found that the variability of miRNA expression in cancerous tissues was lower than that in normal tissues. Alterations in miRNA expression in gastric adenocarcinoma tissues in comparison to healthy tissues of each individual serves for identification of consistent biomarkers that can be used for development of diagnostic tools for gastric cancer.

miR-370 is better than miR-375 as a non-invasive diagnostic biomarker for pediatric acute myeloid leukemia patients

BACKGROUND: Acute myeloid leukemia (AML) is characterized by heterogeneity in phenotypic, genotypic, and clinical traits. miRNAs play an important role in pathogenesis and diagnosis of adult AML. Such information is not available about miRNA expression role in pediatric AML. OBJECTIVE: We aimed to investigate the expression of miR-370 and miR-375 as new diagnostic biomarkers to discriminate pediatric AML patients and to predict their roles in the disease molecular basis. METHODS: The expression of both miR-370 and miR-375 in peripheral blood (PB) of pediatric AML patients was assessed by QPCR; their impact for diagnosis was evaluated by ROC curve and their roles in pediatric AML development were predicted by bioinformatics analysis. RESULTS: The expression of miR-370 and miR-375 levels were significantly decreased in pediatric AML patients, suggesting them as tumor suppressor miRNAs as supported by bioinformatics analysis. MiR-370 showed better potential and sensitivity toscreen pediatric AML patients and more significant correlation with AML risk than miR-375. This is the first study to report the positive correlation between both miR-370 and miR-375. CONCLUSION: miR-370 level in peripheral blood can serve as a potential non-invasive diagnostic biomarker and was significantly correlated with AML risk. We strongly recommend PB miRNAs as diagnostic biomarkers for pediatric AML.

MiR-375 reduces the stemness of gastric cancer cells through triggering ferroptosis

BACKGROUND

Gastric cancer stem cells (CSCs) are the main causes of metastasis and drug resistance. We previously indicated that miR-375 can inhibit Helicobacter pylori-induced gastric carcinogenesis; here, we aim to explore the effects and mechanisms of miR-375 on gastric cancer (GC) cell stemness.

METHODS

Lentivirus infection was used to construct GC cells with ectopic expression of miR-375. In vitro and in vivo experiments, including analysis of tumor spheroid formation, CD44+ sub-population with stemness, stemness marker expression, and tumor-initiating ability, were performed to evaluate the effects of miR-375 on the stemness of GC cells. Furthermore, microarray and bioinformatics analysis were performed to search the potential targets of miR-375 in GC cells. Luciferase reporter, RNA immunoprecipitation, and RNA-FISH assays were carried out to verify the targeting of miR-375. Subsequently, combined with tissue microarray analysis, erastin-resistant GC cells, transmission electron microscopy, a series of agonists and oxidative stress markers, the underlying mechanisms contributing to miR-375-mediated effects were explored.

RESULTS

MiR-375 reduced the stemness of GC cells in vitro and in vivo. Mechanistically, SLC7A11 was identified as a direct target of miR-375 and miR-375 attenuated the stemness of GC cells mainly through triggering SLC7A11-dependent ferroptosis.

CONCLUSION

MiR-375 can trigger the ferroptosis through targeting SLC7A11, which is essential for miR-375-mediated inhibition on GC cell stemness. These results suggest that the miR-375/SLC7A11 regulatory axis could serve as a potential target to provoke the ferroptosis and thus attenuate the stemness of GC cells.

The impact of microRNAs on myeloid-derived suppressor cells in cancer

Inflammation promotes cancer development. To a large extent, this can be attributed to the recruitment of myeloid-derived suppressor cells (MDSCs) to tumors. These cells are known for establishing an immunosuppressive tumor microenvironment by suppressing T cell activities. However, MDSCs also promote metastasis and angiogenesis. Critically, as small non-coding RNAs that regulate gene expression, microRNAs (miRNAs) control MDSC activities. In this review, we discuss how miRNA networks regulate key MDSC signaling pathways, how they shape MDSC development, differentiation and activation, and how this impacts tumor development. By targeting the expression of miRNAs in MDSCs, we can alter their main signaling pathways. In turn, this can compromise their ability to promote multiple hallmarks of cancer. Therefore, this may represent a new powerful strategy for cancer immunotherapy.

MicroRNA-653-5p Promotes Gastric Cancer Proliferation and Metastasis by Targeting the SOCS6-STAT3 Pathway

MicroRNAs (miRNAs) are emerging as significant regulators of the tumorigenesis of gastric cancer (GC), and may be effective biomarkers for diagnosis, prognosis, and therapeutic targeting for GC. In this study, miR-653-5p was found to be significantly upregulated in GC tissues, serum, and cell lines and was strongly associated with poor prognosis in patients with GC. Furthermore, miR-653-5p promoted GC cell proliferation and metastasis in vivo and in vitro. Suppressor of cytokine signaling 6 (SOCS6) was directly targeted by miR-653-5p, and SOCS6 attenuated miR-653-5p-mediated GC cell growth, migration, and invasion. In addition, SOCS6-mediated inactivation of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway was also reversed by the administration of miR-653-5p. The findings from this study support a novel regulatory axis between miR-653-5p, SOCS6, and JAK2/STAT3 that may be a target for diagnosis and therapeutic intervention for GC.

miR-1225-5p inhibits non-small cell lung cancer cell proliferation, migration and invasion, and may be a prognostic biomarker

Non-small cell lung cancer (NSCLC) is a malignant tumor, which presents with a high 5-year mortality rate owing to the lack of an effective early screening tool and the absence of obvious early symptoms. MicroRNAs (miRs/miRNAs) have attracted increasing attention due to their significant clinical value in the diagnosis and prognosis of various human malignancies. The present study aimed to investigate the expression levels of microRNA (miR)-1225-5p in NSCLC and to analyze its prognostic value and biological role. The expression levels of miR-1225-5p in the tissues of patients with NSCLC and NSCLC cell lines were analyzed using reverse transcription-quantitative PCR. The association between miR-1225-5p expression levels and the clinicopathological features of patients with NSCLC was analyzed using a χ² test. The prognostic value of miR-1225-5p in NSCLC was analyzed using both Kaplan Meier survival and Cox regression analyses, and the effects of miR-1225-5p on NSCLC cell proliferation, migration and invasion were examined. The results revealed that the expression levels of miR-1225-5p were significantly downregulated in NSCLC tissues compared with normal control tissues. Furthermore, miR-1225-5p was discovered to be a potential independent prognostic factor in NSCLC. The inhibition of miR-1225-5p in NSCLC cell lines led to increased cell proliferation, migration and invasion, whereas miR-1225-5p overexpression exerted the opposite effects in these cells. In conclusion, the findings of the present study indicated that the downregulated expression levels of miR-1225-5p in NSCLC may predict a poor prognosis in patients and suggested miR-1225-5p as a potential therapeutic target for NSCLC.

Effects of lncRNA TUSC7 on the malignant biological behavior of osteosarcoma cells via regulation of miR-375

The present study aimed at investigating how long-chain non-coding RNA (lncRNA) tumor suppressor candidate 7 (TUSC7) regulates the malignant biological behavior of osteosarcoma cells. Tumor tissues and adjacent tissues of 30 patients with osteosarcoma were collected, and the expression levels of lncRNA TUSC7 and miR-375 were detected by RT-qPCR. lncRNA TUSC7 mimic and miR-375 mimic transfection models were established in MG63 osteosarcoma cells, and Transwell assays were used to detect the migration ability of MG63 cells. An MTT assay was used to assess the proliferation ability of MG63 cells. lncRNA TUSC7 in osteosarcoma tissue was significantly lower than that of adjacent tissues, while miR-375 levels were significantly higher than that of adjacent tissues; the two levels have a negative correlation. lncRNA TUSC7 mimic inhibited MG63 proliferation and migration abilities. miR-375 mimic promoted MG63 proliferation and migration abilities. The lncRNA TUSC7 mimic and miR-375 mimic co-transfection system could partially rescue the inhibition of lncRNA TUSC7 mimic on MG63 cells. In conclusion, lncRNA TUSC7 inhibited the proliferation and migration of MG63 osteosarcoma cells by regulating miR-375.

Metabolic reprogramming results in abnormal glycolysis in gastric cancer: a review

The Warburg effect in tumor cells involves the uptake of high levels of glucose, enhanced glycolysis, and the metabolism of pyruvate to lactic acid rather than oxidative phos-phorylation to generate energy under aerobic conditions. This effect is closely related to the occurrence, invasion, metastasis, drug resistance, and poor prognosis of gastric cancer (GC). Current research has further demonstrated that the Warburg effect in GC cells is not only mediated by the glycolysis pathway, but also includes roles for mitochondria, noncoding RNAs, and other proteins that do not directly regulate metabolism. As a result, changes in the glycolysis pathway not only lead to abnormal glucose metabolism, but they also affect mitochondrial functions, cellular processes such as apoptosis and cell cycle regulation, and the metabolism of lipids and amino acids. In this review, we discuss metabolic reprogramming in GC based on glycolysis, a possible link between glucose metabolism, lipid metabolism, and amino acid metabolism, and we clarify the role of mitochondria. We also examine recent studies of metabolic inhibitors in GC.

The role of microRNAs involved in PI3-kinase signaling pathway in colorectal cancer

In recent decades, cancer has been one of the most important concerns of the human community, which affects human life from many different ways, such as breast, lung, colorectal, prostate, and other cancers. Colorectal cancer is one of the most commonly diagnosed cancers in the world that has recently been introduced as the third leading cause of cancer deaths in the world. microRNAs have a very crucial role in tumorgenesis and prevention of cancer, which plays a significant role with influencing various factors through different signaling pathways. Phosphoinositide 3 (PI3)-kinase/AKT is one of the most important signaling pathways involved in the control and growth of tumor in colorectal cancer, through important proteins of this pathway, such as PTEN and AKT, that they can perform specific influence on this process. Our effort in this study is to collect microRNAs that act as tumor suppressors and oncomirs in this cancer through PI3-kinase/AKT signaling pathway.

microRNA-375 inhibits colorectal cancer cells proliferation by downregulating JAK2/STAT3 and MAP3K8/ERK signaling pathways

MicroRNA-375 is involved in many types of alimentary system cancers. Our previous studies showed that microRNA-375 was significantly down-regulated in carcinoma tissues compared with para-carcinoma tissues, which strongly indicates that microRNA-375 might suppress the occurrence and development of colorectal cancer. However, the mechanism underlying the microRNA-375 regulation in colorectal cancer remains unclear. In this study, we first sorted out jak2, map3k8 and atg7 as microRNA-375 targeted genes from multiple databases, and found that jak2, map3k8 and their downstream genes stat3 and erk were up-regulated in carcinoma tissues. Secondly, we over-expressed microRNA-375 in colorectal cancer cell lines (HCT116, Caco2 and HT29). Our results showed that in microRNA-375 over-expressing cells, JAK2/STAT3 and MAP3K8/ERK proteins were down-regulated, cell proliferation was inhibited, cell migration rate did not change. There was no significant difference on ATG7 expression between the control group and microRNA-375 over-expressing HT29/Caco2 cells, whereas microRNA-375 down-regulated ATG7 specifically in HCT116 cells. Finally, we demonstrated that expressing microRNA-375 suppressed tumor formation in nude mice. In conclusion, microRNA-375 might function as a tumor-repressive gene to inhibit cell proliferation, mainly through targeting both JAK2/STAT3 and MAP3K8/ERK signaling pathways in colorectal cancer. These findings suggest miR-375 as a promising diagnostic marker and a therapeutic drug for colorectal cancer.

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.

May Circulating microRNAs be Gastric Cancer Diagnostic Biomarkers?

Gastric cancer (GC) is the third leading cause of cancer-related deaths. More than 80% of the diagnosis was made at the advanced stages of the disease, highlighting the urgent demand for novel biomarkers that can be used for early detection. Recently, a number of studies suggest that circulating microRNAs (miRNAs) could be potential biomarkers for GC diagnosis. Cancer-related circulating miRNAs, as well as tissue miRNAs, provide a hopeful prospect of detecting GC at early stages, and the prospective participation of miRNAs in biomarker development will enhance the sensitivity and specificity of diagnostic tests for GC. As miRNAs in blood are stable, their potential value as diagnostic biomarkers in GC has been explored over the past few years. However, due to the inconsistent or sometimes conflicting reports, large-scale prospective studies are needed to validate their potential applicability in GC diagnosis. This review summarizes the current development about potential miRNA biomarkers for GC diagnosis and the obstacles hindering their clinical usage.

MiR-375 targets KLF4 and impacts the proliferation of colorectal carcinoma

MiR-375 has been identified as oncogenes or tumor suppressor genes which has the potential to the development and growth of cancers. However, the limited information concerning the expression and role of miR-375 in colorectal cancer (CRC) is available. In this work, we provide evidence for a function of miR-375 in the inhibition of CRC proliferation. Here, we showed that miR-375, down-modulated in human colorectal cancer tissues compared with normal human colon tissues, including several colorectal cancer cell lines. Subsequently, using the luciferase reporter assays, we found that the KLF4 untranslated region (3'UTR) carries the direct binding site of miR-375. In terms of function in vitro, CCK-8 assay, colony formation assay, and cell cycle assay demonstrated that the overexpression of miR-375 suppressed CRC cell proliferation. Inhibition of KLF4 performed similar effects with miR-375 overexpression on CRC cells, and overexpression of KLF4 could significantly reverse the tumor suppressive effects of miR-375 on CRC cells. Furthermore, we found overexpressed miR-375 effectively repressed tumor growth via KLF4 in xenograft animal experiment. Taken together, these results illustrated that miR-375 depresses proliferation of CRC through regulating 3'UTR of KLF4 mRNA, which might be a promising therapeutic target for treating colorectal cancers.

MicroRNA-375 functions as a tumor suppressor in osteosarcoma by targeting PIK3CA

Osteosarcoma has become one of the most common primary malignant bone tumors in childhood and adult. Numerous studies have demonstrated that aberrant microRNA (miRNA) expression is involved in human disease including cancer. To date, the potential miRNAs regulating osteosarcoma growth and progression are not fully identified yet. Herein, we showed that miR-375 was frequently downregulated in osteosarcoma tissue and cell lines compared to normal human colon tissues. Overexpression of miR-375 resulted in decreased expression of PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha) at both mRNA and protein levels. We found that miR-375 overexpression markedly suppressed cell proliferation in vitro. And inhibition of miR-375 promotes osteosarcoma growth. Mechanistic studies showed that PIK3CA was a potential target of miR-375 and it mediated reduction of PIK3CA resulted in suppression of PI3K/Akt pathway. Taken together, our results demonstrate that miR-375 functions as a growth-suppressive miRNA and plays an important role in inhibiting the tumorigenesis through targeting PIK3CA in osteosarcoma.

miR-375 inhibits Helicobacter pylori-induced gastric carcinogenesis by blocking JAK2-STAT3 signaling

Gastric cancer remains the second leading cause of cancer-related deaths worldwide. Although Helicobacter pylori (H. pylori) is considered to be a critical risk factor, the molecular mechanisms underlying H. pylori-induced gastric carcinogenesis are still poorly defined. Recently, accumulating studies have revealed that microRNAs play key roles in development, differentiation, immune regulation, and even carcinogenesis. This study was performed to explore the mechanism of microRNA-375 (miR-375) in H. pylori promotion of gastric carcinogenesis. It was shown that miR-375 was down-regulated in response to H. pylori infection in gastric epithelial cell lines; this finding was quite opposite to the expression patterns of pro-inflammatory cytokines observed in a co-culture cell model. Moreover, the ectopic expression of miR-375 aggravated cell proliferation and migration. It was further observed that Janus kinase 2 (JAK2) was a bona fide target of miR-375 and further activated signal transducer and activator of transcription 3 (STAT3) and other downstream target molecules. Both gain-of-function and loss-of-function experiments showed that decreased miR-375 expression could mimic the oncogenic effects of the JAK2-STAT3 pathway. In addition, pretreatment with siRNAs targeting JAK2 prevented gastric epithelial cells from increasing proliferation and migration even in response to H. pylori infection. For the first time, our results demonstrate that the JAK2-STAT3 pathway regulated by miR-375 is involved in H. pylori-induced inflammation; this pathway promotes neoplastic transformation by affecting the expression of BCL-2 and TWIST1, hence offering a potential therapeutic target for inflammation-related cancers, especially those related to H. pylori.

Epigenetics: An emerging player in gastric cancer

Cancers, like other diseases, arise from gene mutations and/or altered gene expression, which eventually cause dysregulation of numerous proteins and noncoding RNAs. Changes in gene expression, i.e., upregulation of oncogenes and/or downregulation of tumor suppressor genes, can be generated not only by genetic and environmental factors but also by epigenetic factors, which are inheritable but nongenetic modifications of cellular chromosome components. Identification of the factors that contribute to individual cancers is a prerequisite to a full understanding of cancer mechanisms and the development of customized cancer therapies. The search for genetic and environmental factors has a long history in cancer research, but epigenetic factors only recently began to be associated with cancer formation, progression, and metastasis. Epigenetic alterations of chromatin include DNA methylation and histone modifications, which can affect gene-expression profiles. Recent studies have revealed diverse mechanisms by which chromatin modifiers, including writers, erasers and readers of the aforementioned modifications, contribute to the formation and progression of cancer. Furthermore, functional RNAs, such as microRNAs and long noncoding RNAs, have also been identified as key players in these processes. This review highlights recent findings concerning the epigenetic alterations associated with cancers, especially gastric cancer.

MicroRNA-375 inhibits colorectal cancer growth by targeting PIK3CA

Colorectal cancer (CRC) is the second most common cause of death from cancer. MicroRNAs (miRNAs) represent a class of small non-coding RNAs that control gene expression by triggering RNA degradation or interfering with translation. Aberrant miRNA expression is involved in human disease including cancer. Herein, we showed that miR-375 was frequently down-regulated in human colorectal cancer cell lines and tissues when compared to normal human colon tissues. PIK3CA was identified as a potential miR-375 target by bioinformatics. Overexpression of miR-375 in SW480 and HCT15 cells reduced PIK3CA protein expression. Subsequently, using reporter constructs, we showed that the PIK3CA untranslated region (3'-UTR) carries the directly binding site of miR-375. Additionally, miR-375 suppressed CRC cell proliferation and colony formation and led to cell cycle arrest. Furthermore, miR-375 overexpression resulted in inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. SiRNA-mediated silencing of PIK3CA blocked the inhibitory effect of miR-375 on CRC cell growth. Lastly, we found overexpressed miR-375 effectively repressed tumor growth in xenograft animal experiments. Taken together, we propose that overexpression of miR-375 may provide a selective growth inhibition for CRC cells by targeting PI3K/Akt signaling pathway.

Upregulation of microRNA-375 is associated with poor prognosis in pediatric acute myeloid leukemia

A genome-wide serum miRNA expression analysis previously showed the upregulation of microRNA-375 (miR-375) in acute myeloid leukemia (AML) patients compared with healthy controls. The aim of this study was to investigate the expression patterns and the prognostic relevance of miR-375 in pediatric AML. Expression levels of miR-375 in bone marrow mononuclear cells were detected by real-time quantitative PCR in a cohort of 106 patients with newly diagnosed pediatric AML. Expression levels of miR-375 in the bone marrow of pediatric AML patients were significantly higher than those in normal controls (P < 0.001). Then, miR-375 upregulation occurred more frequently in French-American-British classification subtype M7 than in other subtypes (P < 0.001). Regarding to cytogenetic risk, the expression levels of miR-375 in pediatric AML patients with unfavorable karyotypes were dramatically higher than those in intermediate and favorable groups (P = 0.002). Moreover, high miR-375 expression was significantly associated with shorter relapse-free survival (P < 0.001) and overall survival (P < 0.001) in pediatric AML patients. Multivariate analysis further identified miR-375 expression and cytogenetics risk as independent prognostic factors for both relapse-free survival and overall survival. In particular, the prognostic relevance of miR-375 expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics. Our findings suggest for the first time that the upregulation of miR-375 may be one of the molecular mechanisms involved in the development and progression of pediatric AML. Since its correlation with poor relapse-free survival and overall survival, miR-375 may be a novel biomarker to improve the management of pediatric AML patients.

miRNA: The nemesis of gastric cancer (Review)

microRNAs (miRNAs) are a group of small non-coding RNAs that are ~22 (18 to 25) nucleotides (nt) long and have been associated with a variety of diseases, including cancer. Increasing evidence indicates that miRNAs are essential in the development, diagnosis, treatment and prognosis of a variety of tumors. The utility of miRNAs as biomarkers for diagnosis and of target molecules for the treatment of cancers is increasingly being recognized. With the discovery of circulating miRNAs, a non-invasive approach for the diagnosis and treatment of cancer has been identified. This review summarizes the role of miRNAs in the development of different tumors, as well as a variety of other biological events. Moreover, this review focuses on analyzing the function and mechanism of gastric cancer-related miRNAs and investigates the importance of circulating miRNAs in gastric cancer, as well as their origin. Finally, this review lists a number of the problems that must be solved prior to miRNAs being used as reliable non-invasive tools for the diagnosis, treatment and prognosis of gastric cancer.

Correlation of microRNA-375 downregulation with unfavorable clinical outcome of patients with glioma

BACKGROUND AND AIM

MicroRNA-375 (miR-375) is frequently demonstrated to be frequently dysregulated and functions as a tumor suppressor or an oncogene in different cancer types. However, its roles in human gliomas have not been reported. The aim of this study was to investigate the expression pattern and clinical significance of miR-375 in patients with gliomas.

METHODS

Real-time quantitative RT-PCR assay was performed to detect miR-375 expression in human gliomas and non-neoplastic brain tissues. Then, the association of miR-375 expression with clinicopathological factors and prognosis of glioma patients was also statistically analyzed.

RESULTS

miR-375 expression was significantly decreased on average in glioma tissues relative to non-neoplastic brain tissues (P<0.0001) with ascending pathological grade. Then, the low miR-375 expression in glioma tissues was significantly associated with advanced pathological grade (P=0.003) and low Karnofsky performance score (KPS, P=0.01). Moreover, both univariate and multivariate Cox regression analyses determined that loss of miR-375 expression effectively predicted the decreased overall survival in patients with gliomas.

CONCLUSIONS

These findings offer the first convinced evidence that the downregulation of miR-375 expression in human gliomas may play an inhibitory role during the tumor development. This miRNA might function as a candidate unfavorable prognostic marker for human gliomas.

H. pylori eradication did not improve dysregulation of specific oncogenic miRNAs in intestinal metaplastic glands

BACKGROUND

Many microRNAs (miRNAs) are differentially expressed in Helicobacter pylori-infected gastric mucosa and in gastric cancer tissue.

AIM

We aimed to compare the effect of H. pylori eradication on gastric mucosal miRNAs in subjects in a high-risk group for gastric cancer compared to controls.

METHODS

Patients with a recent history of endoscopic resection for early gastric cancer and sex- and age-matched non-cancer controls were enrolled. The expression of 21 miRNAs was examined using gastric mucosal biopsy specimens and microdissected gastric glands from the lesser and greater curvatures of the gastric corpus both before and one year after H. pylori eradication.

RESULTS

Twenty patients and 14 controls were enrolled. The expression of oncogenic miRNAs (miR-17/92 and the miR-106b-93-25 cluster, miR-21, miR-194, and miR-196) was significantly higher in the gastric mucosa of the cancer group than in the controls. H. pylori eradication resulted in a significant fall in the expression of oncogenic miRNAs only in the controls, whereas miR-223 expression was decreased and let-7d expression was increased in both groups. miR-196 was expressed only in intestinal metaplastic glands. The expression of oncogenic miRNAs was significantly higher in the intestinal metaplastic glands than in the non-intestinal metaplastic glands irrespective of H. pylori eradication. In neither group did H. pylori eradication significantly change any miRNA expression in the intestinal metaplastic glands.

CONCLUSION

Dysregulation of specific miRNAs is present in H. pylori-induced corpus gastritis. H. pylori eradication improved miRNA dysregulation, but not in intestinal metaplastic glands or in the gastric mucosa of patients in a high-risk group for gastric cancer.

The role of microRNAs in Helicobacter pylori pathogenesis and gastric carcinogenesis

Gastric carcinogenesis is a multistep process orchestrated by aberrancies in the genetic and epigenetic regulation of oncogenes and tumor suppressor genes. Chronic infection with Helicobacter pylori is the strongest known risk factor for the development of gastric cancer. H. pylori expresses a spectrum of virulence factors that dysregulate host intracellular signaling pathways that lower the threshold for neoplastic transformation. In addition to bacterial determinants, numerous host and environmental factors increase the risk of gastric carcinogenesis. Recent discoveries have shed new light on the involvement of microRNAs (miRNAs) in gastric carcinogenesis. miRNAs represent an abundant class of small, non-coding RNAs involved in global post-transcriptional regulation and, consequently, play an integral role at multiple steps in carcinogenesis, including cell cycle progression, proliferation, apoptosis, invasion, and metastasis. Expression levels of miRNAs are frequently altered in malignancies, where they function as either oncogenic miRNAs or tumor suppressor miRNAs. This review focuses on miRNAs dysregulated by H. pylori and potential etiologic roles they play in H. pylori-mediated gastric carcinogenesis.

Targeting microRNAs involved in human diseases: a novel approach for modification of gene expression and drug development

The identification of all epigenetic modifications (i.e. DNA methylation, histone modifications and expression of noncoding RNAs such as microRNAs) involved in gene regulation is one of the major steps forward for understanding human biology in both normal and pathological conditions and for development of novel drugs. In this context, microRNAs play a pivotal role. This review article focuses on the involvement of microRNAs in the regulation of gene expression, on the possible role of microRNAs in the onset and development of human pathologies, and on the pharmacological alteration of the biological activity of microRNAs. RNA and DNA analogs, which can selectively target microRNAs using Watson-Crick base pairing schemes, provide a rational and efficient way to modulate gene expression. These compounds, termed antago-miR or anti-miR have been described in many examples in the recent literature and have proved to be able to perform regulatory as well as therapeutic functions. Among these, a still not fully exploited class is that of peptide nucleic acids (PNAs), promising tools for the inhibition of miRNA activity, with important applications in gene therapy and in drug development. PNAs targeting miR-122, miR-155 and miR-210 have already been developed and their biological effects studied both in vitro and in vivo.