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Poster Session (ID 8)
- Event: ACLC 2018
- Type: Poster Session
- Presentations: 1
- Coordinates: 11/07/2018, 00:00 - 00:00, Poster Hall
P077 - miR-338-3p Promotes the Resistance of Non-Small Cell Lung Cancers To EGFR-TKI By Targeting PTPN12 (ID 186)
00:00 - 00:00 | Author(s): F. Xu
Most of patients harboring EGFR activating mutations will inevitably acquire resistance to EGFR-TKI after 6-12 months of treatment. The T790M mutation in exon 20 of EGFR gene is the main cause of drug resistance, accounting for about 50%. The third-generation TKI targeting T790M mutation has been marketed and used in clinical practice, such as Osimertinib (AZD9291), but there are still nearly 50% of TKI resistance mechanisms unknown or currently lack of clinical approaches for reversing drug resistance. Therefore, exploring the molecular mechanism of T790M-negative EGFR-TKI secondary drug resistance has become a hot spot in lung cancer research. A growing number of studies found that microRNA (miRNA) plays an important role in the regulation of acquired drug resistance of EGFR-TKI, and it is expected to reverse acquired resistance of EGFR TKIs.
Cell viabilities of PC9 and PC9/BB4 cells was detected by CCK-8 method, the EdU method was used to detect cell proliferation, cell apoptosis was detected by FACS, and plate colony assay was used to detect colony formation ability. Western blot detected to difference of EGFR downstream signaling pathways in PC9 and PC9/BB4 cells.
The results of in vitro experiments indicated that miR-338-3p was down-regulated in Gefitinib-sensitive PC9 cell and highly expressed in PC9/BB4 resistant cells. Up-regulation or down-regulation of miR-338-3p, respectively, can alter the effect of Gefitinib on the survival, proliferation, apoptosis and clonality of PC9 and PC9/BB4 cells, and can regulate the activity of p-Akt and p-Erk1/2 protein, indicating miR -338-3p promotes EGFR-TKI resistance in non-small cell lung cancer by activating EGFR downstream signaling pathway. Using bioinformatics software to predict and confirm by dual luciferase reporter system, PTPN12 is a downstream target gene of miR-338-3p. PTPN12 protein is highly expressed in PC9 cells, low in PC9/BB4 cells, and can interfere with Gefitinib sensitivity after interfering with PTPN12 expression level in PC9 and PC9/BB4 cells, respectively. In vitro experiments demonstrated that miR-338-3p activates EGFR downstream PI3K/Akt and Ras/Raf/Erk signaling pathways by targeting PTPN12, and promote Gefitinib resistance in non-small cell lung cancer. Further study showed that down-regulation of miR-338-3p by miR-338-3p antagomir reversed the resistance of PC9/BB4 xenografts to Gefitinib by activating PTPN12.
We conclude that alteration of miR-338-3p/PTPN12 expression as a novel mechanism for EGFR-TKI resistance in NSCLC. miR-338-3p/PTPN12 could serve as a therapeutic target for overcoming EGFR-TKI resistance in NSCLC.