Background Autophagy has been found to be involved in the multidrug resistance (MDR) of cancers, but whether it is associated with resistance of small cell lung cancer (SCLC) has not been studied. Here, we hypothesized that a potential autophagy-regulating miRNA, miR-199a-5p, regulated cisplatin-resistant SCLC. Methods We validated the MDR of H446/EP using CCK-8 and LDH. We tested the binding of miR-199a-5p to p62 using the Dual-Luciferase assay and validated the association of miR-199a-5p and p62 in SCLC samples. We overexpressed (OE) and knocked down (KD) miR-199a-5p in H446 and H446/EP and determined the expression of miR-199a-5p, autophagy-related proteins, and the formation of autophagolysosomes using QPCR, western blotting, and MDC staining respectively. These results were validated in an orthotopic H446 mouse model of SCLC. Results H446/EP was resistant to cisplatin, etoposide, paclitexal, epirubicin, irinotecan, and vinorelbine. Exposure of cisplatin at 5 μg/ml for 24 h increased LC3II/LC3I, ATG5, p62, and the formation of autophagolysosomes in H446 cells, but not in H446/EP cells. The expression of miR-199a-5p was up-regulated in H446/EP compared to H446. MiR-199a-5p directly targeted the p62 gene. The expression of miR-199a-5p and p62 were correlated in SCLC samples. In H446 and H69PR, the OE of miR-199a-5p increased LC3II/LC3I, p62, and the formation of autophagolysosomes, but not ATG5, while the KD of miR-199a-5p decreased p62, but did not affect LC3II/LC3I, ATG5, and the formation of autophagolysosomes. In H446/EP, the OE of miR-199a-5p decreased p62 only. These results were generally consistent to results in the animal tumor samples. Conclusions The regulation of autophagy by the miR-199a-5p/p62 axis was a potential mechanism of small cell lung cancer cisplatin resistance.
Background Esophageal cancer is one of the most common cancers across the globe; the 5‐year survival of esophageal cancer patients is still low. MicroRNA (miRNA) dysregulation has been implicated in cancer development, and the miRNAs play a pivotal role in esophageal cancer pathogenesis. It is urgently needed to find out how miRNA dysregulation was involved in esophageal cancer (EC) development. Methods Through experiments in vivo and in vitro, we explored potential signaling pathways, miR‐493/Wnt5A/c‐JUN loop, in EC. Their mechanistic roles in EC cell proliferation, migration, and invasion were investigated through multiple validation steps in EC9706 and TE13 cell lines and EC specimens. Results Overexpression of miR‐493 attenuates esophageal cancer cell proliferation, migration, and invasion in vivo and in vitro. Moreover, miR‐493 downregulation is an unfavorable factor in EC and negatively correlated with Wnt5A. The existence of miR‐493 is also an important attribute of metabolism. Based on mechanism analyses, we show that miR‐493 inhibits the activity of c‐JUN and p‐PI3K/p‐AKT with enhanced p21 and directly regulates Wnt5A expression and function, whereas c‐JUN binds the promoter region of miR‐493 and suppressed the expression of miR‐493, forming a negative feedback loop. Conclusions The miR‐493/Wnt5A/c‐JUN loop is a molecular feedback loop that refers to the development of esophageal cancer cells and a potential target for the treatment of esophageal cancer.
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Background miRNA dysregulation has been implicated in cancer development.Methods In the present study, we use cell culture and transfection, the tissue specimens, RNA isolation and RT-PCR, Western blot and so on to explore the role of miR-493 in esophageal cancer.Results Overexpression of miR-493 attenuates esophageal cancer cell proliferation, migration, and invasion in vivo and in vitro. Moreover, miR-493 downregulation is an unfavorable factor in EC and negatively correlated with Wnt5A. The existence of miR-493 is also an important attribute of metabolism. Based on mechanism analyses, we show that miR-493 inhibits the activity of c-JUN and p-PI3K/p-AKT with enhanced p21 and directly regulates Wnt5A expression and function, while, c-JUN binds the promoter region of miR-493 and suppressed the expression of miR-493, forming a negative feedback loop. Moreover, miR-493 regulates the expression of PD-L1 by c-JUN and then the sensitivity of EC cells to DDP.Conclusions the results elucidate a molecular feedback loop that involves miR-493, Wnt5A, c-JUN and PD-L1 in EC. In future, these mechanistic findings provide a useful therapeutic option for the treatment of EC.
Background Multidrug resistance (MDR) in small cell lung cancer (SCLC) is a clinical dilemma in chemotherapy. A natural compound, β-elemene has been found to inhibit MDR cancers. We hypothesized that β-elemene regulated cisplatin-resistant SCLC by targeting autophagy-related miRNA miR-199a-5p. Methods We assessed the IC50 of multiple chemotherapeutic agents toward SCLC cells H446 and MDR SCLC cells H446/EP with or without β-elemene using CCK-8. We overexpressed (OE) and knocked down (KD) miR-199a-5p in H446 and H446/EP and determined the expression of miR-199a-5p, autophagy-related proteins, and the formation of autophagolysosomes using QPCR, western blotting, and MDC staining respectively. We validate the binding of miR-199a-5p to p62 using the Dual-Luciferase assay. Results β-Elemene decreased drug resistance of H446 to cisplatin, etoposide, paclitexal, epirubicin, irinotecan, and vinorelbine. Cisplatin increased LC3II/LC3I, ATG5, p62, and the formation of autophagolysosomes in H446 cells, but not in H446/EP cells, and these effects were blocked by β-elemene. The OE of miR-199a-5p reduced cisplatin-induced increase of LC3II/LC3I, ATG5, p62, and the formation of autophagolysosomes while the KD of miR-199a-5p did the opposite. the OE of miR-199a-5p reduced the luciferase signal of wild-type p62, but not that of p62 with mutations at the predicted binding site. The effect of β-elemene on cisplatin-induced autophagy was validated in OE-H446 and KD-H446/EP. Conclusions β-Elemene prevented MDR in H446 and it prevents cisplatin resistance of H446 by targeting the autophagy regulation of miR-199a-5p.
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