Table_1_Cleavage and Polyadenylation Specific Factor 1 Promotes Tumor Progression via Alternative Polyadenylation and Splicing in Hepatocellular Carcinoma.DOCX

Alternative polyadenylation (APA) is an important post-transcriptional regulatory mechanism required for cleavage and polyadenylation (CPA) of the 3′ untranslated region (3′ UTR) of mRNAs. Several aberrant APA events have been reported in hepatocellular carcinoma (HCC). However, the regulatory mechanisms underlying APA remain unclear. In this study, we found that the expression of cleavage and polyadenylation specific factor 1 (CPSF1), a major component of the CPA complex, was significantly increased in HCC tissues and correlated with unfavorable survival outcomes. Knockdown of CPSF1 inhibited HCC cell proliferation and migration, whereas overexpression of CPSF1 caused the opposite effect. Based on integrative analysis of Iso-Seq and RNA-seq data from HepG2.2.15 cells, we identified a series of transcripts with differential 3′ UTR lengths following the knockdown of CPSF1. These transcripts were related to the biological functions of gene transcription, cytoskeleton maintenance, and endomembrane system transportation. Moreover, knockdown of CPSF1 induced an increase in alternative splicing (AS) events in addition to APA. Taken together, this study provides new insights into our understanding of the post-transcriptional regulatory mechanisms in HCC and implies that CPSF1 may be a potential prognostic biomarker and therapeutic target for HCC.

选择性 polyadenylation（APA）是 mRNA 3′ 不翻译区（3′ UTR）剪接和 polyadenylation（CPA）过程中不可或缺的转录后调控机制。在肝细胞癌（HCC）中，已报道存在多种 APA 异常事件。然而，APA 的调控机制尚不明确。本研究中，我们发现剪接和 polyadenylation 特异性因子 1（CPSF1），CPA 复合体的主要成分，在 HCC 组织中的表达显著增加，并与不良的生存结果相关。CPSF1 的敲低抑制了 HCC 细胞的增殖和迁移，而 CPSF1 的过表达则产生相反的效果。基于 HepG2.2.15 细胞的 Iso-Seq 和 RNA-seq 数据的整合分析，我们鉴定出一系列在 CPSF1 敲低后 3′ UTR 长度发生差异的转录本。这些转录本与基因转录、细胞骨架维持和内质网系统运输的生物学功能相关。此外，CPSF1 的敲低不仅诱导了 APA 事件的发生，还引起了选择性剪接（AS）事件的增加。综上所述，本研究为理解 HCC 中的转录后调控机制提供了新的见解，并暗示 CPSF1 可能是 HCC 的潜在预后生物标志物和治疗靶点。