探討PHRF1誘導HCT116-p53-/-直腸癌細胞侵襲之功能

Abstract

PHRF1 (PHD and RING Finger Domains 1)是具有E3 ubiquitin ligase功能的核蛋白，透過其 N 端的 RING 結構域降解TGIF（TG 交互因子），並且在不同癌細胞中促進 TGF-β信號傳導。然而，在被活化的原致癌突變基因 Kras和被剔除的抑癌基因p53的遺傳背景下，PHRF1對細胞功能之影響尚不清楚。本研究透過CRISPR-Cas9技術，在大腸癌細胞HCT116-p53-/-（KrasG13D/p53-/-）中敲除PHRF1基因表達，觀察對HCT116-p53-/-PHRF1-/-細胞功能的變化和影響為何。與我們先前在肺癌A549（KrasG12S/p53wt)細胞中的結果不同，在 PHRF1 缺失的HCT116-p53-/-細胞中，我們發現SRY-box轉錄因子4 (SOX4）可能是關鍵的下游效應因子，其表現量下降與細胞的侵襲能力降低有關。根據次世代定序（Next-Generation Sequencing）結果顯示，SOX4對於調控HCT116-p53-/-PHRF1-/-細胞侵襲能力至關重要，研究發現PHRF1透過C端SRI結構域可誘導SOX4的表現並影響大腸癌細胞的移動能力，將SOX4重新導入HCT116-p53-/-PHRF1-/-細胞後，可以部分恢復細胞的侵襲能力。這些發現強調了PHRF1在結直腸癌HCT116-p53-/- 細胞中調控細胞侵襲的作用。綜上所述，這些結果揭示了PHRF1在結直腸癌腫瘤發生過程中的新功能，特別是在KrasG13D突變和p53缺失的遺傳背景下。我們證實了PHRF1透過其C端的SRI結構域，調控SOX4的表現量，來促進細胞的侵襲能力。為PHRF1在大腸癌惡性腫瘤的發展中，提供了一個新的觀點。

PHRF1 (PHD and RING Finger Domains 1) functions as an E3 ubiquitin ligase that enhances TGF-β signaling through its N-terminal RING domain by targeting TGIF (TG-interacting factor) for degradation in different cancer cells. However, the effects of PHRF1 on cell motility in the context of activated oncogenic Kras and inactivated tumor suppressor p53 have yet to be clarified. Our study aims to investigate the cellular outcomes when PHRF1 was knocked out by using CRISPR-Cas9 gene editing in colorectal cancer HCT116-p53-/- (KrasG13D/p53-/-) cells. By analyzing the resulting gene expression profiles in HCT116-p53-/-PHRF1-/- cells, we found that SOX4 (SRY-box transcription factor 4) was potentially a key downstream effector, whose downregulation correlated with reduced invasive potential in these cells. According to next-generation sequencing analysis, PHRF1 is crucial for regulating cell invasion ability and SOX4 expression. Our evidence suggests that PHRF1 induces cellular motility by modulating the C-terminal SRI domain. Importantly, SOX4 reintroduction could partially restore the invasion ability in HCT116-p53-/-PHRF1-/- cells. These findings highlight the effects of PHRF1 in modulating cell invasion in colorectal cancer HCT116-p53-/- cells. Collectively, these results uncover a novel function of PHRF1 in colorectal cancer tumorigenesis, particularly within the genetic context of KrasG13D mutation and p53 loss. Our findings demonstrate that PHRF1 promotes cellular invasion by modulating SOX4 expression through its C-terminal SRI domain, offering new mechanistic insights into its role in driving malignancy