The Human RNA Surveillance Factor UPF1 Modulates Gastric Cancer Progression by Targeting Long Non-Coding RNA MALAT1.

BACKGROUND/AIMS: The long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is overexpressed in numerous cancers. However, whether MALAT1 is regulated and the related mechanisms in gastric cancer remain unclear.

METHODS

Immunohistochemistry and qRT-PCR analyses were used to detect the expression levels of UPF1 and MALAT1 in gastric cancer and adjacent normal tissues. MTT, cell cycle, apoptosis and transwell assays were performed to examine the effects of UPF1 on cell cycle progression, cell proliferation, apoptosis, migration and invasion. Additionally, sodium bisulfate sequencing was used to test the promoter hypermethylation on UPF1 in gastric tumor tissues. Finally, RNA immunoprecipitation and luciferase reporter analyses demonstrated that UPF1 directly bound with MALAT1.

RESULTS

The expression of UPF1 was significantly downregulated in gastric cancer and negatively correlated with MALAT1 expression. Patients with lower expression of UPF1 had poorer prognosis than those with higher expression. Overexpression of UPF1 inhibited cell proliferation, cell cycle progression, cell migration and invasion, and promoted cell apoptosis in gastric cancer cells. Moreover, the UPF1-mediated inhibition of gastric cancer progression was reversed by overexpression of MALAT1. A profound downregulation of UPF1 in gastric tumor tissues was due to promoter hypermethylation. Overexpression of UPF1 increased nonsense-mediated mRNA decay (NMD) efficiency and thus led to downregulation of MALAT1.

CONCLUSION

Our results demonstrate that UPF1 is a potential modulator of MALAT1 and that UPF1/MALAT1 pathway could be a therapeutic target for gastric cancer.