N6-methyladenosine-modified long non-coding RNA KIF9-AS1 promotes stemness and sorafenib resistance in hepatocellular carcinoma by upregulating SHOX2 expression.

Hepatocellular carcinoma (HCC) is a prevalent and aggressive tumor. Sorafenib is the first-line treatment for patients with advanced HCC, but resistance to sorafenib has become a significant challenge in this therapy. Cancer stem cells play a crucial role in sorafenib resistance in HCC. Our previous study revealed that the long non-coding RNA (lncRNA) KIF9-AS1 is an oncogenic gene in HCC. However, the role of KIF9-AS1 in drug resistance and cancer stemness in HCC remains unclear. Herein, we aimed to investigate the function and mechanism of the lncRNA KIF9-AS1 in cancer stemness and drug resistance in HCC. To describe the role of the lncRNA KIF9-AS1 in cancer stemness and drug resistance in HCC and elucidate the underlying mechanism. Tumor tissue and adjacent non-cancerous tissue samples were collected from HCC patients. Sphere formation was quantified via a tumor sphere assay. Cell viability, proliferation, and apoptosis were evaluated via Cell Counting Kit-8, flow cytometry, and colony formation assays, respectively. The interactions between the lncRNA KIF9-AS1 and its downstream targets were confirmed via RNA immunoprecipitation and coimmunoprecipitation. The tumorigenic role of KIF9-AS1 was validated in a mouse model. Compared with that in normal controls, the expression of the lncRNA KIF9-AS1 was upregulated in HCC tissues. Knockdown of KIF9-AS1 inhibited stemness and attenuated sorafenib resistance in HCC cells. Mechanistically, N6-methyladenosine modification mediated by methyltransferase-like 3/insulin-like growth factor 2 mRNA-binding protein 1 stabilized and increased the expression of KIF9-AS1. Additionally, KIF9-AS1 increased the stability and expression of short stature homeobox 2 by promoting ubiquitin-specific peptidase 1-induced deubiquitination. Furthermore, depletion of KIF9-AS1 alleviated sorafenib resistance in a xenograft mouse model of HCC. The N6-methyladenosine-modified lncRNA KIF9-AS1 promoted stemness and sorafenib resistance in HCC by upregulating short stature homeobox 2 expression.

Yu Y ，Lu XH ，Mu JS ，Meng JY ，Sun JS ，Chen HX ，Yan Y ，Meng K ... -  《-》

Decreased lncRNA HNF4A-AS1 facilitates resistance to sorafenib-induced ferroptosis of hepatocellular carcinoma by reprogramming lipid metabolism.

Background: Resistance to sorafenib remains a major challenge in the systemic therapy of liver cancer. However, the involvement of lipid metabolism-related lncRNAs in this process remains unclear. Methods: Different expression levels of lipid metabolism-related lncRNAs in HCC were compared by analysis of Gene Expression Omnibus and The Cancer Genome Atlas databases. The influence of HNF4A-AS1 on sorafenib response was evaluated through analysis of public biobanks, cell cytotoxicity and colony formation assays. The effect of HNF4A-AS1 on sorafenib-induced ferroptosis was measured using lipid peroxidation, glutathione, malondialdehyde, and ROS levels. Furthermore, bioinformatic analyses and lipidomic profiling were conducted to study HNF4A-AS1 involvement in lipid metabolic reprogramming. Mechanistic experiments, including the luciferase reporter assay, RNA pulldown, RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation (MeRIP), and RNA remaining assays, were employed to uncover the downstream targets and regulatory mechanisms of HNF4A-AS1 in sorafenib resistance in HCC. Xenograft and organoid experiments were carried out to assess the impact of HNF4A-AS1 on sorafenib response. Results: Bioinformatics analysis revealed that HNF4A-AS1, a lipid metabolism-related lncRNA, is specifically high-expressed in the normal liver and associated with sorafenib resistance in HCC. We further confirmed that HNF4A-AS1 was downregulated in HCC cells and organoids that resistant to sorafenib. Moreover, both in vitro and in vivo studies demonstrated that HNF4A-AS1 overexpression reversed sorafenib resistance in HCC cells, which was further enhanced by polyunsaturated fatty acids (PUFA) supplementation. Mechanistically, HNF4A-AS1 interacted with METTL3, leading to m6A modification of DECR1 mRNA, which subsequently decreased DECR1 expression via YTHDF3-dependent mRNA degradation. Consequently, decreased HNF4A-AS1 levels caused DECR1 overexpression, leading to decreased intracellular PUFA content and promoting resistance to sorafenib-induced ferroptosis in HCC. Conclusions: Our results indicated the pivotal role of lipid metabolism-related and liver-specific HNF4A-AS1 in inhibiting sorafenib resistance by promoting ferroptosis and suggesting that HNF4A-AS1 might be a potential target for HCC.

Zhao Y ，Han S ，Zeng Z ，Zheng H ，Li Y ，Wang F ，Huang Y ，Zhao Y ，Zhuo W ，Lv G ，Wang H ，Zhao G ，Zhao E ，Hu Y ，Hu P ，Zhao G ... -  《Theranostics》

CircSCMH1 Accelerates Sorafenib Resistance in Hepatocellular Carcinoma by Regulating HN1 Expression via miR-485-5p.

Sorafenib (SOR) is the first-line chemotherapeutic therapy for hepatocellular carcinoma (HCC) treatment, but SOR resistance is a key factor affecting the therapeutic effect. Emerging studies have suggested that circular RNAs (circRNAs) play an important role in the development of drug resistance in HCC cells. This paper aimed to elucidate the potential role and molecular mechanism of circRNA Scm polycomb group protein homolog 1 (circSCMH1) in SOR-resistant HCC cells. CircSCMH1, microRNA-485-5p (miR-485-5p), and hematological and neurological expressed 1 (HN1) contents were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell Counting Kit-8 (CCK8) assay was adopted to detect the SOR sensitivity of cells. Cell proliferation, migration, invasion, and apoptosis were assessed using colony formation, 5-Ethynyl-2'-deoxyuridine (EdU), transwell, and flow cytometry assays. Glucose metabolism was analyzed using commercial kits. HN1, B cell lymphoma-2 (Bcl-2), and Bcl-2-associated X (Bax) protein levels were assessed using western blot. Binding between miR-485-5p and circSCMH1 or HN1 was verified using a dual-luciferase reporter. Xenograft tumor model was used to explore the function of circSCMH1 in vivo. CircSCMH1 expression and HN1 abundances were increased, but the miR-485-5p level was reduced in SOR-resistant HCC tissues and cells. Deficiency of circSCMH1 enhanced SOR sensitivity by suppressing cell proliferation, migration, invasion, and glucose metabolism and inducing cell apoptosis in SOR-resistant HCC cell lines (Huh7/SOR and Hep3B/SOR). Mechanistically, circSCMH1 sponged miR-485-5p to positively regulate HN1 expression. Importantly, circSCMH1 depletion inhibited tumor growth and increased SOR sensitivity in vivo. CircSCMH1 promoted SOR resistance in HCC cells at least partly through upregulating HN1 expression by sponging miR-485-5p. These findings elucidated a new regulatory pathway of chemo-resistance in SOR-resistant HCC cells and provided a possible circRNA-targeted therapy for HCC.

Li M ，Pang X ，Xu H ，Xiao L ... -  《-》

5-methylcytosine methylation of MALAT1 promotes resistance to sorafenib in hepatocellular carcinoma through ELAVL1/SLC7A11-mediated ferroptosis.

Emerging evidence demonstrates that long non-coding RNAs (lncRNAs) play a crucial role in sorafenib resistance in hepatocellular carcinoma (HCC), and lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a dysregulated lncRNA in sorafenib-resistant HCC cells. However, the underlying regulatory mechanisms of MALAT1 in sorafenib-resistant HCC cells remain unclear. In the present study, we demonstrated that 5-methylcytosine (m5C) methylation catalyzed by NSUN2 and ALYREF contributed to the RNA stability and upregulation of MALAT1. The NSUN2/ALYREF/MALAT1 signaling axis was activated in sorafenib-resistant cells, and the upregulation of MALAT1 inhibited sorafenib-induced ferroptosis to drive sorafenib resistance. Mechanistically, MALAT1 maintained the mRNA stability of SLC7A11 by directly binding to ELAVL1 and stimulating its cytoplasmic translocation. Furthermore, we explored a new synergetic strategy for the treatment of HCC by combining MALAT1 inhibitor MALAT1-IN1 with sorafenib. The results demonstrated that MALAT1-IN1 significantly enhanced sorafenib efficacy for the treatment of HCC both in vitro and in vivo. Collectively, our work brings new insights into the epigenetic mechanisms of sorafenib resistance and offers an alternative therapeutic strategy targeting ferroptosis for sorafenib-resistant HCC patients.

Shi CJ ，Pang FX ，Lei YH ，Deng LQ ，Pan FZ ，Liang ZQ ，Xie T ，Wu XL ，Wang YY ，Xian YF ，Zeng WQ ，Lin HL ，Zhang JF ... -  《-》

Exosomal miR-6126 as a novel therapeutic target for overcoming resistance of anti-cancer effect in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) stands as the sixth most prevalent cancer globally, presenting a substantial health challenge, particularly due to late-stage diagnoses that limit treatment effectiveness. Sorafenib, a multi-kinase inhibitor, is the primary chemotherapeutic agent for advanced HCC, but it only extends survival by 2-3 months. However, drug resistance remains a major clinical challenge, necessitating the exploration of new molecular mechanisms, including the role of microRNAs (miRNAs) in sorafenib resistance. In this study, we aimed to identify miRNAs within exosomes derived from sorafenib-resistant HCC cells to elucidate the molecular mechanisms underlying resistance. Sorafenib-resistant cells were generated by culturing the human HCC cell line Huh7 in a medium containing 20 µM sorafenib for six months. Exosomes were isolated from the conditioned medium 24 h before cell harvest using exosome-depleted serum medium. miRNA sequencing and western blotting were used to analyze the expression profiles of exosomal miRNAs and proteins, respectively. pH measurement was performed to assess pH changes in response to sorafenib treatment and miRNA modulation. A total of 180 exosomal miRNAs were found to be dysregulated between sorafenib-treated control Huh7 (Huh7S) and sorafenib-resistant Huh7 (Huh7RS) cells, as well as between untreated control Huh7 and Huh7RS cells. Among these, miR-6126 was significantly downregulated in Huh7RS cells compared to Huh7S cells. Functional studies using 2-dimensional (D) and 3D cell culture systems revealed that miR-6126 overexpression reduced sorafenib resistance in Huh7RS cells, while its inhibition increased resistance in Huh7 cells. miR-6126 downregulated key proteins involved in cancer stem cell maintenance, such as CD44 and HK2. Furthermore, the pH level was elevated in cells overexpressing miR-6126 following sorafenib treatment, whereas inhibiting miR-6126 resulted in a lower pH. Exosomal miR-6126 plays a pivotal role in sorafenib resistance and tumorigenesis, highlighting its potential as a novel therapeutic target for overcoming drug resistance in HCC.

Hwang H ，Kim J ，Kim TH ，Han Y ，Choi D ，Cho S ，Kim S ，Park S ，Park T ，Piccinini F ，Rhee WJ ，Pyun JC ，Lee M ... -  《BMC CANCER》