Prognostic Value of microRNA-9 in Various Cancers: a Meta-analysis

miR-9 Does Not Regulate Lamin A Expression in Metastatic Cells from Lung Adenocarcinoma

In lung adenocarcinoma, low lamin A expression in pleural metastatic cells has been proposed as a pejorative factor. miR-9 physiologically inhibits the expression of lamin A in neural cells and seems to be a central actor in the carcinogenesis and the metastatic process in lung cancer. Thus, it could be a good candidate to explain the reduction of lamin A expression in lung adenocarcinoma cells. miR-9 expression was analyzed in 16 pleural effusions containing metastatic cells from lung adenocarcinoma and was significantly reduced in patients from the 'Low lamin A expression' group compared to patients from the 'High lamin A expression' group. Then, carcinoma cells selection by fluorescence-activated cell sorting (FACS) was performed according to epithelial membrane antigen (EMA) expression, reflecting lamin A expression. miR-9 was underexpressed in lamin A- carcinoma cells compared to lamin A+ carcinoma cells in patients from the 'Low lamin A expression' group, whereas there was no difference of miR-9 expression between lamin A+ and lamin A- carcinoma cells in patients from the 'High lamin A expression' group. These results suggest that miR-9 does not regulate lamin A expression in metastatic cells from lung adenocarcinoma. On the contrary, miR-9 expression was shown to be reduced in lamin A-negative carcinoma cells.

MicroRNAs associated with microvascular invasion in hepatocellular carcinoma and their prognostic impacts in patients undergoing hepatic resection

Although microvascular invasion (McVI) has prognostic value for patients with hepatocellular carcinoma (HCC) who have undergone hepatic resection, few studies have investigated the relationship between McVI and the aberrant expression of microRNAs (miRNAs). The present study identified the miRNAs that were selectively expressed in HCC with McVI and investigated their prognostic value. Clinical data and the miRNA expression profiles of 372 patients with HCC were extracted from The Cancer Genome Atlas database. miRNAs that were differentially expressed between patients with McVI and those without vascular invasion (VI) were identified and investigated as potential prognostic factors for HCC. The results demonstrated that McVI was a significant predictor of shortened recurrence-free survival (RFS). The 3 year RFS rate in patients with HCC accompanied by McVI was 28.2 and 49.3% in HCC without VI (P<0.001). miRNA-141/-582/-9 were upregulated, while miRNA-675 was downregulated in patients with McVI when compared with HCC patients without VI. Log₂ fold-changes of miRNA-141/-582/-675/-9 were 0.80 [false discovery rate (FDR), 0.005], 0.55 (FDR, 0.045), -0.99 (FDR, 0.005) and 1.22 (FDR, <0.001), respectively. Kaplan-Meier analysis indicated that the overexpression of miR-141/-582/-9 was significantly associated with poor RFS and a poor overall survival. A text mining analysis revealed that these miRNAs were significantly associated with multifaceted hallmarks of cancer, including 'invasion and metastasis'. In conclusion, the overexpression of miRNA-141/-582/-9 was associated with McVI and a poor survival in patients undergoing hepatic resection for HCC.

miR-9: From function to therapeutic potential in cancer

Malignant neoplasms are regarded as the main cause of death around the world; hence, many research studies were conducted to further perceive molecular mechanisms, treatment, and cancer prognosis. Cancer is known as a major factor for health-related problems in the world. The main challenges associated with these diseases are prompt diagnosis, disease remission classification and treatment status forecast. Therefore, progressing in such areas by developing new and optimized methods with the help of minimally invasive biological markers such as circular microRNAs (miRNAs) can be considered important. miRNA interactions with target genes have specified their role in development, apoptosis, differentiation, and proliferation and also, confirm direct miRNA function in cancer. Different miRNAs expression levels in various types of malignant neoplasms have been observed to be associated with prognosis of various carcinomas. miR-9 seems to implement opposite practices in different tissues or under various cancer incidences by influencing different genes. Aberrant miR-9 levels have been observed in many cancer types. Therefore, we intended to investigate the precise role of miR-9 in patients with malignant neoplasms. To this end, in this study, we attempted to examine different studies to clarify the overall role of miR-9 as a prognostic marker in several human tumors. The presented data in this study can help us to find the novel therapeutic avenues for treatment of human cancers.