PIK3C2A is a gene-specific target of microRNA-518a-5p in imatinib mesylate-resistant gastrointestinal stromal tumor

Abstract

Imatinib mesylate resistance occurs in some patients with gastrointestinal stromal tumors (GISTs) during the course of treatment. In this study, we investigated the relationship between microRNAs (miRNAs) and imatinib-resistant GISTs, and the effect of miR-518a-5p on PIK3C2A in imatinib-resistant GISTs. A total of 20 matched-pair GIST samples from imatinibresistant patients were included in the study. Each of the paired tumor specimens were from the same patient who had surgical removal of GISTs preimatinib and postimatinib treatment. Seven pairs of tissues were resected for microarray analysis, and the remaining 13 pairs were utilized for miRNAs analysis. Target genes were selected based on bioinformatics from multiple biological databases. Luciferase reporter assays were used to confirm the binding of miR-518a-5p to PIK3C2A 3′UTR. GIST882R-NC, 882R-miR-518a-5p-OE, and 882R-miR-518a-5p-KD cell lines were constructed using lentiviral vectors. miR-518a-5p and PIK3C2A expression in 882R-NC, 882R-OE, and 882R-KD cells was assessed by real-time PCR and western blotting. A cell counting kit was used to detect the influence of miR-518a-5p to cell proliferation. TUNEL staining was applied to detect the influence of miR-518a-5p to cell apoptosis. Microarray analysis showed that miR-518a-5p was downregulated in imatinib-resistant GISTs, and the expression of miR-518a-5p was confirmed with good concordance between real-time PCR and miRNA microarray results. Luciferase reporter assays indicated that miR-518a-5p bound to the PIK3C2A 3′UTR. Compared with 882R-OE, PIK3C2A expression was significantly increased in 882R-KD cells. MiR-518a-5p reduced 882R proliferation and promoted 882R apoptosis. In conclusion, PIK3C2A is a gene-specific target of miR-518a-5p in imatinib mesylate-resistant GISTs. Low expression of miR-518a-5p is likely to upregulate PIK3C2A and affect the cellular response to the drug, causing resistance to imatinib in GISTs.

Inhibition of stromal‐interacting molecule 1‐mediated store‐operated Ca2+ entry as a novel strategy for the treatment of acquired imatinib‐resistant gastrointestinal stromal tumors

“…Another study reports that apoptosis induced by miR-518a-5p affected the cellular response to the drug, causing imatinib resistance in GIST. 31 We have also found previously that STIM1-mediated SOCE contributes to apoptosis via phosphorylation of the MEK/ERK pathway, which is a classical signaling pathway that participates in cell growth, EMT and apotosis. 32 STIM1-knockdown cells in the present study had lower levels of phosphorylated MEK and ERK than that of control cells, whereas total protein levels were unaffected.…”

The Network of Non-coding RNAs in Cancer Drug Resistance

“…Another report showed that miR-7 could work in synergy with imatinib to sensitize K562 (456). As the last ncRNA in this subnetwork, miR-518a is down-regulated in imatinib-resistant gastrointestinal stromal tumor (GIST) and PIK3C2A was identified as the relevant specific target (457). …”

Gastrointestinal stromal tumors (GIST): Facing cell death between autophagy and apoptosis

“…MIR17, MIR20A, MIR221-MIR222 ! mimics as a promising approach in TKI-resistant GIST [106]. MIR518A-5p !…”

“…105 Recently, Shi and collaborators reported a correlation between MIR518A-5p and apoptosis. 106 The authors found MIR518A-5p downregulation in imatinib-resistant GIST patients by miRNA microarray and provided evidence of a functional interaction with the 3 0 UTR of the PIK3C2A gene. The PIK3C2A gene belongs to the phosphatidylinositol (PtdIns) 3-kinase family, which regulates various cellular processes, including cell growth, proliferation and apoptosis.…”

“…The authors showed PIK3C2A downregulation, both at mRNA and protein levels, after MIR518A-5p transfection, indicating that low expression of MIR518A-5p is likely to cause PIK3C2A upregulation, promoting cancer survival, and prompting resistance to imatinib in GIST. 106 …”