The regulation of autophagy by the miR-199a-5p/p62 axis was a potential mechanism of small cell lung cancer cisplatin resistance

Abstract

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.

miR-199a: A Tumor Suppressor with Noncoding RNA Network and Therapeutic Candidate in Lung Cancer

“…miR-199a is also involved in cellular autophagy via signaling pathways. For example, miR-199a-5p blocked autophagy by activating the PI3K/Akt/mTOR signaling pathway and inhibiting the expression of autophagy-related proteins [ 43 ].…”

“…In contrast, in multidrug-resistant cell lines (H446/EP), the overexpression of miR-199a-5p only decreased P62. In conclusion, the miR-199a-5p/p62 axis regulates autophagy as a potential mechanism of cisplatin resistance in SCLC [ 43 ]. Zeng et al [ 79 ] showed that miR-199a-5p expression was up-regulated in paclitaxel-resistant lung cancer cell lines (A549 and H1299).…”

Progress in the studies on the molecular mechanisms associated with multidrug resistance in cancers

“…The regulation of autophagy to overcome MDR has become high-lightened in cancer chemotherapy 148 . A bundle of autophagy-related pathways and factors, such as autophagy-related 16 like 1 (ATG16 L1) 150 , ATG5 151 , PI3K/AKT/mTOR pathway 152 , 153 , AMP-activated protein kinase (AMPK) 154 , miR-199a-5p/p62 axis 155 , METase/lncRNA HULC/FoxM1 156 , p53 157 , transcription factor EB (TFEB) 158 and non-steroidal anti-inflammatory drugs (NSAIDs) 159 , were reported to regulate cell autophagy and autophagy associated MDR in cancers. By elevating miR-30a expression level, LC3-II expression was downregulated in gastric cancer cells, and this could lead to inhibition of the chemoresistance-associated autophagy 160 .…”

Emerging role of non-coding RNAs in resistance to platinum-based anti-cancer agents in lung cancer

“…Lower expression of miR-199a-5p increased p62, thereby promoting the transformation of LC3I to LC3II. Therefore, regulation of p62-mediated autophagy by miR-199a-5p was found to be a potential mechanism of SCLC cisplatin resistance ( Li T. et al, 2022a ). Uncoordinated-51-like kinase 1 (ULK1), an autophagy-related gene, is involved in the chemoresistance of diverse human cancers like liver, breast, and colon cancer.…”