Tumor expression of miR-448 is a prognostic marker in oral squamous cell carcinoma

MiR-448 suppresses cell proliferation and glycolysis of hepatocellular carcinoma through inhibiting IGF-1R expression

BACKGROUND

Microribonucleic acids (miRNAs) have been shown to play important roles in hepatocellular carcinoma (HCC) progression. MiR-448 has frequently been shown to be a tumor suppressor, and is abnormally expressed in HCC tumor tissues. However, little is known about the role of miR-448 in HCC development. In this article, the regulatory role of miR-448 on insulin-like growth factor 1 receptor (IGF-1R) in modulating hepatoma cell viability and glycolysis was investigated.

METHODS

The expression of miR-448 profiles in clinical tumor tissues and cell lines was examined using quantitative real-time polymerase chain reaction (qRT-PCR). HepG2 and Huh7 cells were transfected with miR-448 mimics, inhibitors, and scramble sequences. Cell viability and apoptosis were determined by a Cell Counting Kit-8 assay and a flow cytometry analysis. IGF-1R, a potential target of miR-448, was selected following a bioinformatic analysis, and the regulatory effects of miR-448 on IGF-1R expression was confirmed by luciferase reporter assay, qRT-PCR, and western blot. Glucose uptake, lactate production, and adenosine triphosphate (ATP) generation were detected by corresponding kits.

RESULTS

Decreased miR-448 expression was observed in both HCC patients' tumor tissues and hepatoma cells in vitro. The overexpression of miR-448 in HepG2 and Huh7 cells decreased cell viability and increased apoptosis. Additionally, the overexpression of miR-448 or the knockdown of IGF-1R lowered the level of glucose uptake, lactate production, and ATP generation, while the knockdown of miR-448 increased glycolysis. Further, aberrantly expressed miR-448 downregulated IGF-1R levels, while the inhibition of miR-448 resulted in the upregulation of IGF-1R in both HepG2 and Huh7 cells. In addition, miR-448 interacted with the wild-type 3'untranslated regions (3'UTRs) of IGF-1R, but had no effect on the mutant 3'UTRs. The expression of IGF-1R was increased in HCC patients' tumor tissues and serum, and was inversely correlated with miR-448 expression.

CONCLUSIONS

The increased expression of miR-448 appears to downregulate the expression of IGF-1R by interacting with the 3'UTR in HCC progression. These findings highlight its role as a potential target for HCC therapy.

Investigation of LINC00493/SMIM26 Gene Suggests Its Dual Functioning at mRNA and Protein Level

The amount of human long noncoding RNA (lncRNA) genes is comparable to protein-coding; however, only a small number of lncRNAs are functionally annotated. Previously, it was shown that lncRNAs can participate in many key cellular processes, including regulation of gene expression at transcriptional and post-transcriptional levels. The lncRNA genes can contain small open reading frames (sORFs), and recent studies demonstrated that some of the resulting short proteins could play an important biological role. In the present study, we investigate the widely expressed lncRNA LINC00493. We determine the structure of the LINC00493 transcript, its cell localization and influence on cell physiology. Our data demonstrate that LINC00493 has an influence on cell viability in a cell-type-specific manner. Furthermore, it was recently shown that LINC00493 has a sORF that is translated into small protein SMIM26. The results of our knockdown and overexpression experiments suggest that both LINC00493/SMIM26 transcript and protein affect cell viability, but in the opposite manner.