Background miR-194-5p has been associated with drug resistance in many cancers. However, the role of miR-194-5p in cisplatin resistance in ovarian cancer is still unclear. Materials and methods To study the role and mechanism of miR-194-5p in cisplatin resistance, qRT-PCR was performed to determine the expression of miR-194-5p and SLC40A1 in ovarian cancer. Cell Counting Kit-8 (CCK8) assay was used to analyse cell viability after cisplatin treatment . Dual-luciferase reporter gene assay was performed to examine the relationship between miR-194-5p and SLC40A1. The genes downstream of SLC40A1 were investigated through bioinformatics analysis. Results Compared to cisplatin-sensitive ovarian cancer cells , higher miR-194-5p expression and lower SLC40A1 expression were found in cisplatin-resistant ovarian cancer cells. Moreover, this study demonstrated that over-expression of miR-194-5p inhibited SLC40A1 expression, and knockdown of miR-194-5p promoted SLC40A1 expression. In addition, dual-luciferase reporter gene assay further confirmed the negative correlation between miR-194-5p and SLC40A1. Furthermore, we found that over-expression of miR-194-5p resulted in cisplatin resistance. When miR-194-5p and SLC40A1 were simultaneously up-regulated, cisplatin sensitivity increased, while down-regulation of miR-194-5p sensitised ovarian cancer cells to cisplatin. However, when miR-194-5p and SLC40A1 were simultaneously down-regulated, cisplatin sensitivity was decreased. These data suggested that miR-194-5p inhibited SLC40A1 expression to induce cisplatin resistance. In addition, bioinformatics analysis indicated a positive correlation of SLC40A1 with hephaestin (HEPH), and homeostatic iron regulator (HFE). However, we found that HEPH and HFE were associated with cisplatin resistance, suggesting that their role in drug resistance is induced by miR-194-5p/SLC40A1. Conclusion In conclusion, we found that miR-194-5p inhibited SLC40A1 expression to induce cisplatin resistance in ovarian cancer. This study suggests that miR-194-5p could be a potential therapeutic target and a prognostic biomarker for ovarian cancer, with important implications for future research.
Induction of Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) has been demonstrated to be involved in cisplatin resistance in ovarian cancer. Solute carrier family 40 member 1 (SLC40A1) is an iron exporter, which possesses many putative Nrf2 binding sites. Here we hypothesize that it may be a possible downstream gene of Nrf2. Elevated level of Nrf2 and reduced level of SLC40A1 were found in cisplatin–resistant ovarian cancer cells as compared with cisplatin-sensitive ovarian cancer cells. Exogenous knockdown of Nrf2 leaded to increased expression of SLC40A1. While overexpression of Nrf2 resulted in decreased expression of SLC40A1. Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay revealed that Nrf2 inhibited the transcription of SLC40A1. Overexpression of SLC40A1 was able to reverse cisplatin resistance induced by Nrf2, while knockdown of SLC40A1 restored cisplatin resistance and increased iron concentration. Desferal, an iron chelator, was found to overcome cisplatin resistance through iron deprivation. Its function was boosted when combined with brusatol, an Nrf2 inhibitor. Taken together, this study first demonstrated that Nrf2 could transcriptionally suppress the expression of SLC40A1. Iron overload induced by SLC40A1 resulted in cisplatin resistance in ovarian cancer. Targeting iron metabolism may be a new therapeutic strategy to reverse drug resistance in ovarian cancer treatment.
Although ferroptosis as an emerging way exhibits tremendous promising in the therapy of hepatocellular carcinoma (HCC), the novel therapeutic agents targeting ferroptosis are still scarce. In our previous study, we found that the natural products toosendanin (TSN) possessed significant anti-proliferative efficacy by regulating WW domain-containing oxidoreductase (WWOX) in HCC. However, there is very limited understanding about TSN-induced ferroptosis, and the role of WWOX in ferroptosis has not been studied. In present study, we investigated the effect and underlying molecular mechanisms of TSN in WWOX-mediated ferroptosis in HCC. We found that TSN induced ferroptosis in HCC cells and its effect was dependent on WWOX. RNA-seq and RT-qPCR assay identified that TSN significantly increased spermidine/spermine N1-acetyltransferase 1 (SAT1) expression while decreased solute carrier family 40 member 1 (SLC40A1) expression, which play vital roles in ferrous ion transport. Further dual-luciferase reporter assay and Co-IP assay revealed that TSN-induced WWOX activation controlled the transcriptional activity of p53 and NF-E2-related factor 2 (NRF2) by regulating their interaction. Meanwhile, IF assay and WB assay confirmed that TSN increased the nuclear distribution of p-WWOX and p-p53 dimers, but impeded the nuclear translocation of NRF2 by inducing its ubiquitination degradation, ultimately regulating the transcription of their downstream target genes. In addition, the results from cell viability assay and the tumor xenograft model verified that co-treatment of TSN, ML385 (NRF2 inhibitor), and MIRA-1 (p53 activator) could effectively inhibit HCC cells growth in the presence of Fer-1 (ferroptosis inhibitor) in vitro and in vivo. Overall, our study contributes to the necessary understanding of the molecular mechanisms of WWOX-mediated ferroptosis regulation, and identifies TSN as a potential therapeutic agent targeting ferroptosis for HCC.
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