Reduced miR-433 expression is associated with advanced stages and early relapse of colorectal cancer and restored miR-433 expression suppresses the migration, invasion and proliferation of tumor cells in vitro and in nude mice

miR-433 Inhibits Glioblastoma Progression by Suppressing the PI3K/Akt Signaling Pathway Through Direct Targeting of ERBB4

Glioblastoma multiforme (GBM) is a highly malignant brain tumor where new biomarkers and drug targets are much needed in the oncology clinic. miR-433 was identified as a tumor-suppressing miRNA in several different types of human cancer. However, the integrative biology of miR-433 in GBM is still largely unknown. By analyzing the expression profiles of miR-433 in 198 patients with glioma at The Cancer Genome Atlas, we found that the miR-433 expression was decreased in glioma whereas the low expression of miR-433 was significantly associated with shorter overall survival. We then conducted in vitro studies and demonstrated that increased expression of miR-433 suppressed the proliferation, migration, and invasion of LN229 and T98G cells, two representative glioma cell lines. Further, using in vivo mouse model, we found that upregulation of miR-433 inhibited the tumor growth of glioma cells. To situate the integrative biology understanding of the action of miR-433 in glioma, we identified ERBB4 as a gene targeted directly by miR-433 in LN229 and T98G cells. Overexpressed ERBB4 rescued the phenotype caused by overexpression of miR-433. Finally, we showed that miR-433 suppressed the PI3K/Akt pathway in glioma cells. In conclusion, our study demonstrated that miR-433 could potentially act as a tumor suppressor for GBM and may serve as a potential therapeutic target for GBM. Further integrative biology and clinical translational research are warranted to evaluate miR-433 in GBM.

MALAT1-miRNAs network regulate thymidylate synthase and affect 5FU-based chemotherapy

Background

The active metabolite of 5-Fluorouracil (5FU), used in the treatment of several types of cancer, acts by inhibiting the thymidylate synthase encoded by the TYMS gene, which catalyzes the rate-limiting step in DNA replication. The major failure of 5FU-based cancer therapy is the development of drug resistance. High levels of TYMS-encoded protein in cancerous tissues are predictive of poor response to 5FU treatment. Expression of TYMS is regulated by various mechanisms, including involving non-coding RNAs, both miRNAs and long non-coding RNAs (lncRNAs).

Aim

To delineate the miRNAs and lncRNAs network regulating the level of TYMS-encoded protein.

Main body

Several miRNAs targeting TYMS mRNA have been identified in colon cancers, the levels of which can be regulated to varying degrees by lncRNAs. Due to their regulation by the MALAT1 lncRNA, these miRNAs can be divided into three groups: (1) miR-197-3p, miR-203a-3p, miR-375-3p which are downregulated by MALAT1 as confirmed experimentally and the levels of these miRNAs are actually reduced in colon and gastric cancers; (2) miR-140-3p, miR-330-3p that could potentially interact with MALAT1, but not yet supported by experimental results; (3) miR-192-5p, miR-215-5p whose seed sequences do not recognize complementary response elements within MALAT1. Considering the putative MALAT1-miRNAs interaction network, attention is drawn to the potential positive feedback loop causing increased expression of MALAT1 in colon cancer and hepatocellular carcinoma, where YAP1 acts as a transcriptional co-factor which, by binding to the TCF4 transcription factor/ β-catenin complex, may increase the activation of the MALAT1 gene whereas the MALAT1 lncRNA can inhibit miR-375-3p which in turn targets YAP1 mRNA.

Conclusion

The network of non-coding RNAs may reduce the sensitivity of cancer cells to 5FU treatment by upregulating the level of thymidylate synthase.

The epigenetic silencing of microRNA-433 facilitates the malignant phenotypes of non-small cell lung cancer by targeting CREB1

OBJECTIVE

MicroRNAs (miRNAs) play a big role in the regulation of non-small cell lung cancer (NSCLC) development. The objective of this study is to determine how DNA methylation regulates miR-433 in NSCLC.

METHODS

The degree of DNA methylation was determined, and the relevance of miR-433 and the features of NSCLC patients were assessed. The MiR-433 and CREB1 expressions were tested, and the biological characteristics of the NSCLC cells were determined. Subcutaneous tumorigenesis in nude mice and luciferase activity assays were performed.

RESULTS

MiR-433 was downregulated, and CREB1 was upregulated in the NSCLC tissues, and the methylating rate of the C-phosphate-G (CpG) island in the miR-433 promoter region was enhanced. MiR-433 was also downregulated, and CREB1 was upregulated in the NSCLC cells and there was a low degree of promoter methylation of miR-433 in the NSCLC cells after demethylation. Upregulated miR-433 or downregulated CREB1 repressed the cell vitality and colony formation abilities and increased the amount of apoptotic A549 cells. Moreover, upregulated miR-433 also decelerated tumor growth. Conversely, the H460 cells and xenografts with reduced miR-433 or overexpressed CREB1 had contrary results. CREB1 was found to be targeted by miR-433, as verified by a luciferase activity assay.

CONCLUSION

We found that DNA methylation can downregulate miR-433 in NSCLC, which promotes the malignant behaviors of NSCLC cells.