RNA-binding protein Trx regulates alternative splicing and promotes metastasis of HCC via interacting with LINC00152.

Epithelial-mesenchymal transition (EMT) is central to HCC metastasis, in which RNA-binding proteins (RBPs) play a key role. To explore the role of RBPs in metastasis of hepatocellular carcinoma (HCC), whole transcriptome sequencing was conducted to identify differential RBPs between HCC with metastasis and HCC without metastasis. The influence of RBPs on metastasis of HCC was verified by in vitro and in vivo experiments. The interaction of RBPs with non-coding RNAs was evaluated by RNA immunoprecipitation and pull-down assays. RNA sequencing, whole-genome sequencing, and alternative splicing analysis were further performed to clarify post-transcriptional regulation mechanisms. Whole transcriptome sequencing results showed that expression of thioredoxin (Trx) was significantly upregulated in HCC patients with metastasis. Trx was also found to be associated with poor prognosis in HCC patients. Overexpression of Trx could promote migration and invasion of HCC cells in vitro and increase the rate of lung metastasis of HCC cells in vivo. Moreover, binding assays showed that Trx could bind to LINC00152. As a result, LINC00152 was verified to determine the pro-metastasis function of Trx by knockdown assay. Furthermore, we revealed that Trx could regulate metastasis-associated alternative splicing program. Specifically, angiopoietin 1 (ANGPT1) was the splicing target; the splicing isoform switching of ANGPT1 could activate the PI3K-Akt pathway, upregulate EMT-associated proteins, and promote migration and invasion of HCC cells. We found that Trx could interact with LINC00152 and promote HCC metastasis via regulating alternative splicing, indicating that Trx may serve as a novel therapeutic target for HCC treatment.

Teng X ，Shang J ，Du L ，Huang W ，Wang Y ，Liu M ，Ma Y ，Wang M ，Tang H ，Bai L ... -  《-》

MicroRNA-34c-3p promotes cell proliferation and invasion in hepatocellular carcinoma by regulation of NCKAP1 expression.

Xiao CZ ，Wei W ，Guo ZX ，Zhang MY ，Zhang YF ，Wang JH ，Shi M ，Wang HY ，Guo RP ... -  《-》

MFSD2A Overexpression Inhibits Hepatocellular Carcinoma Through TGF-β/Smad Signaling.

Hepatocellular carcinoma (HCC) is a common primary malignancy of the liver and has a high mortality. Major facilitator superfamily domain containing 2 (MFSD2A) was previously demonstrated to inhibit tumor progression in several cancers. Here, we elucidated the association between MFSD2A expression and HCC progression and also investigated the underlying mechanism. The online tools were utilized to evaluate MFSD2A expression in HCC samples and predict the prognostic significance of MFSD2A in HCC patients. The biological role of MFSD2A in HCC cellular processes was examined by colony formation, wound healing, transwell, and western blotting. The in vivo role of MFSD2A in HCC was investigated in a xenograft tumor model. The miRNAs and RNA-binding proteins potentially targeting MFSD2A were identified using bioinformatics prediction tools. Luciferase reporter, RNA immunoprecipitation, actinomycin D, and immunofluorescence assays were performed to investigate the molecule mechanisms of MFSD2A. Transforming growth factor (TGF)-β1/Small mothers against decapentaplegic (Smad) signaling was detected using western blot analysis. We found that MFSD2A expression was significantly downregulated in HCC patients and cells and its downregulation predicted a poor prognosis. MFSD2A overexpression repressed HCC cell proliferation, migration, invasion, the epithelial-to-mesenchymal transition in vitro, as well as inhibited HCC tumor growth in vivo. MFSD2A was targeted by miR-3189-3p. High-density lipoprotein binding protein (HDLBP) inhibited MFSD2A expression by binding to and destabilizing MFSD2A mRNA. MFSD2A significantly suppressed activation of TGF-β/Smad signaling in HCC cells. Knockdown of MFSD2A abrogated the inhibitory effect of miR-3189-3p inhibitor on HCC cellular processes, and overexpression of MFSD2A reversed the tumor-promoting effect of HDLBP overexpression. Overall, MFSD2A exerts a tumor-inhibiting effect in HCC via suppression of TGF-β/Smad signaling, suggesting that MFSD2A may be a promising target for HCC therapy.

Xiao C ，Zhao X ，Hu Z ，Long G ... -  《-》

MYBBP1A‑mediated IGFBP4 promoter methylation promotes epithelial‑mesenchymal transition and metastasis through activation of NOTCH pathway in liver cancer.

Sun Y ，Weng X ，Chen W ，Ge J ，Ding B ，Ru J ，Lei Y ，Hu X ，Man D ，Cheng S ，Duan R ，Ren J ，Yang B ... -  《-》

HnRNPR-mediated UPF3B mRNA splicing drives hepatocellular carcinoma metastasis.

Abnormal alternative splicing (AS) contributes to aggressive intrahepatic invasion and metastatic spread, leading to the high lethality of hepatocellular carcinoma (HCC). This study aims to investigate the functional implications of UPF3B-S (a truncated oncogenic splice variant) in HCC metastasis. Basescope assay was performed to analyze the expression of UPF3B-S mRNA in tissues and cells. RNA immunoprecipitation, and in vitro and in vivo models were used to explore the role of UPF3B-S and the underlying mechanisms. We show that splicing factor HnRNPR binds to the pre-mRNA of UPF3B via its RRM2 domain to generate an exon 8 exclusion truncated splice variant UPF3B-S. High expression of UPF3B-S is correlated with tumor metastasis and unfavorable overall survival in patients with HCC. The knockdown of UPF3B-S markedly suppresses the invasive and migratory capacities of HCC cells in vitro and in vivo. Mechanistically, UPF3B-S protein targets the 3'-UTR of CDH1 mRNA to enhance the degradation of CDH1 mRNA, which results in the downregulation of E-cadherin and the activation of epithelial-mesenchymal transition. Overexpression of UPF3B-S enhances the dephosphorylation of LATS1 and the nuclear accumulation of YAP1 to trigger the Hippo signaling pathway. Our findings suggest that HnRNPR-induced UPF3B-S promotes HCC invasion and metastasis by exhausting CDH1 mRNA and modulating YAP1-Hippo signaling. UPF3B-S could potentially serve as a promising biomarker for the clinical management of invasive HCC.

Wang H ，Qian D ，Wang J ，Liu Y ，Luo W ，Zhang H ，Cheng J ，Li H ，Wu Y ，Li W ，Wang J ，Yang X ，Zhang T ，Han D ，Wang Q ，Zhang CZ ，Liu L ... -  《-》