miRNA expression profile in primary gastric cancers and paired lymph node metastases indicates that miR-10a plays a role in metastasis from primary gastric cancer to lymph nodes

Association of the miR-146aC>G, miR-149T>C, and miR-196a2T>C polymorphisms with gastric cancer risk and survival in the Greek population

MicroRNAs (miRNAs) play an important role in regulating gene expression at the post-transcriptional level and are involved in numerous physiological processes. Accumulating evidence suggests that single-nucleotide polymorphisms (SNPs) in human miRNA genes may affect miRNA biogenesis pathway and influence the susceptibility to several diseases such as cancer. The aim of the study was to investigated whether three common miRNA polymorphisms [miR-146a C>G (rs2910164), miR-149 T>C (rs2292832), and miR-196a2 T>C (rs11614913)] are associated with the susceptibility and prognosis of gastric cancer (GC) in the Greek population. The three mRNA SNPs were identified in a case-control study (163 patients; 480 controls) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. We found that the risk for GC was significantly higher for the carriers of miR-149 rs2292832CC (p = 0.009) and miR-196a2 rs11614913CC (p < 0.0001) genotypes, as well as for the carriers of the rs2910164/rs2292832/rs11614913 CCC and GTC haplotype (p < 0.0001 and p = 0.03, respectively). The rs2910164/rs2292832/rs11614913 CTT and CCT haplotypes seems to have a protective role against GC (p = 0.002 and p = 0.001, respectively). Our data demonstrate that specific miRNA SNPs are associated with GC susceptibility in the Greek population.

Identification of microRNAs associated with lymphangiogenesis in human gastric cancer

PURPOSE

Lymphatic metastasis is a primary cause of gastric cancer-related death, yet factors governing tumor cell lymphatic metastasis have not been fully elucidated. MicroRNAs (miRNAs) are a recently discovered class of regulatory, non-coding RNAs, some of which are involved in gastric cancer progression. However, little is known about which miRNA contributes to the lymphatic metastasis in human gastric cancer. This prompted us to find the significant miRNAs associated with lymphangiogenesis in human gastric cancer.

METHODS

We screened vascular endothelial growth factor C (VEGF-C) expression in several gastric cancer cell lines as well as in the immortalized human gastric mucosal cell line GES-1, by real-time reverse transcriptase PCR (qRT-PCR). The gastric cancer cell lines MKN-45 and SGC-7901, which have commonly been cultured with human lymphatic endothelial cells (HLECs) in vitro, promoted tube formation of HLECs following transformation with a VEGF-C expression vector. Using microarrays, we identified a panel of differentially expressed miRNAs in HLECs that had been co-cultured with VEGF-C-transformed gastric cancer cells compared with non-transformed gastric cancer cells. A subset of miRNAs was further validated using qRT-PCR.

RESULTS

We found altered expression of miRNAs in HLECs co-cultured with lymphangiogenesis-inducing VEGF-C-transformed gastric cancer cells, with 47 up-regulated and 42 down-regulated miRNAs. These findings were confirmed by qRT-PCR of selected miRNAs. Furthermore, several miRNAs were differentially expressed in patients with positive lymphatic metastasis of the primary gastric tumor. Up-regulated miRNAs included miR-648, miR-5002-3p, miR-4754, miR-4760-5p, miR-4491, miR-4252, miR-5007-3p, and miR-647; and down-regulated miRNAs included miR-3178, miR-593-5p, miR-4485, miR-135a-3p, miR-17, miR-1469, and miR-124-5p.

CONCLUSIONS

Several lymphangiogenesis-related miRNAs are significantly altered during lymphatic metastasis of gastric cancer.

MiRNA expression signature for potentially predicting the prognosis of ovarian serous carcinoma

One of the best prognostic predictors for patients with epithelial ovarian cancer is the Federation of Obstetrics and Gynecology (FIGO) stage at diagnosis. Advanced-stage ovarian serous carcinoma (OSC) generally have poor prognosis. The goal of this study is to develop and validate a miRNA expression profile that can differentiate the OSC at early and advanced stages and study its correlation with the prognosis of OSC. To identify a unique microRNA (miRNA) pattern associated with the progression of OSC at early and advanced stages, a miRNA microarray was performed using Chinese tumor bank specimens of patients with OSC stage I or III in a retrospective analysis. The expression of four dysregulated miRNAs was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in an external cohort of 51 cases of OSC samples at stages I and III. Kaplan-Meier analysis was performed to analyze the correlation between the expression of some miRNAs and prognosis. Of the 768 miRNAs analyzed in the microarray, 26 miRNAs were significantly either up- or downregulated, with at least a 2-fold difference, in OSC stage I compared with stage III. The qRT-PCR results showed that miR-510, miR-509-5p, and miR-508-3p were significantly downregulated and that miR-483-5p was upregulated in stage III OSC compared with stage I, which was consistent with the microarray results. Kaplan-Meier analysis showed low miR-510 expression, low miR-509-5p expression, and advanced FIGO stage, and chemotherapy resistance were significantly associated with poorer overall survival (P < 0.05). Our results suggest that miRNAs may play a role in the progression of OSC, and miR-510 and miR-509-5p may be considered novel-candidate clinical biomarkers for predicting OSC outcome.

miRNA profiling of cancer

A steadily growing number of studies have shown that microRNAs have key roles in the regulation of cellular processes and that their dysregulation is essential to keep the malignant phenotype of cancer cells. The distorted and unique expression profile of microRNAs in different types and subsets of tumor coupled with their presence in biological fluids make of microRNAs an attractive source of sensitive biomarkers. Here, we will discuss how microRNA profiles are altered in cancer, highlighting their potential as sensitive biomarkers for cancer risk stratification, outcome prediction and classification of histological subtypes. We will also evaluate the current knowledge on the use of microRNAs as circulating biomarkers, hoping that further studies will lead to the application of microRNA signature in prognostic and predictive markers that can improve patient health.