Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, China.
Guangdong Province Key laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, China.
J Exp Clin Cancer Res. 2022 Jan 7;41(1):13. doi: 10.1186/s13046-021-02216-x.
Increasing evidence has suggested inositol polyphosphate 5-phosphatase family contributes to tumorigenesis and tumor progression. However, the role of INPP5F in hepatocellular carcinoma (HCC) and its underlying mechanisms is unclear.
The expression of INPP5F in HCC was analyzed in public databases and our clinical specimens. The biological functions of INPP5F were investigated in vitro and vivo. The molecular mechanism of INPP5F in regulating tumor growth were studied by transcriptome-sequencing analysis, mass spectrometry analysis, immunoprecipitation assay and immunofluorescence assay.
High expression of INPP5F was found in HCC tissues and was associated with poor prognosis in HCC patients. Overexpression of INPP5F promoted HCC cell proliferation, and vice versa. Knockdown of INPP5F suppressed tumor growth in vivo. Results from transcriptome-sequencing analysis showed INPP5F not only regulated a series of cell cycle related genes expression (c-MYC and cyclin E1), but also promoted many aerobic glycolysis related genes expression. Further studies confirmed that INPP5F could enhance lactate production and glucose consumption in HCC cell. Mechanistically, INPP5F activated Notch signaling pathway and upregulated c-MYC and cyclin E1 in HCC via interacting with ASPH. Interestingly, INPP5F was commonly nuclear-located in cells of adjacent non-tumor tissues, while in HCC, cytoplasm-located was more common. LMB (nuclear export inhibitor) treatment restricted INPP5F in nucleus and was associated with inhibition of Notch signaling and cell proliferation. Sequence of nuclear localization signals (NLSs) and nuclear export signals (NESs) in INPP5F aminoacidic sequence were then identified. Alteration of the NLSs or NESs influenced the localization of INPP5F and the expression of its downstream molecules. Furthermore, we found INPP5F interacted with both exportin and importin through NESs and NLSs, respectively, but the interaction with exportin was stronger, leading to cytoplasmic localization of INPP5F in HCC.
These findings indicate that INPP5F functions as an oncogene in HCC via a translocation mechanism and activating ASPH-mediated Notch signaling pathway. INPP5F may serve as a potential therapeutic target for HCC patients.
越来越多的证据表明肌醇多磷酸 5-磷酸酶家族有助于肿瘤发生和肿瘤进展。然而，INPP5F 在肝细胞癌 (HCC) 中的作用及其潜在机制尚不清楚。
在公共数据库和我们的临床标本中分析 INPP5F 在 HCC 中的表达。在体外和体内研究 INPP5F 的生物学功能。通过转录组测序分析、质谱分析、免疫沉淀测定和免疫荧光测定研究 INPP5F 调节肿瘤生长的分子机制。
在 HCC 组织中发现 INPP5F 高表达，与 HCC 患者的预后不良相关。INPP5F 的过表达促进 HCC 细胞增殖，反之亦然。INPP5F 的敲低抑制体内肿瘤生长。转录组测序分析结果表明，INPP5F 不仅调节一系列细胞周期相关基因的表达（c-MYC 和细胞周期蛋白 E1），还促进许多有氧糖酵解相关基因的表达。进一步的研究证实，INPP5F 可以增强 HCC 细胞中的乳酸生成和葡萄糖消耗。在机制上，INPP5F 通过与 ASPH 相互作用激活 Notch 信号通路并上调 HCC 中的 c-MYC 和细胞周期蛋白 E1。有趣的是，在相邻非肿瘤组织的细胞中，INPP5F 通常位于核内，而在 HCC 中，位于细胞质内更为常见。LMB（核输出抑制剂）处理将 INPP5F 限制在核内，与 Notch 信号和细胞增殖的抑制有关。然后鉴定了 INPP5F 氨基酸序列中的核定位信号 (NLS) 和核输出信号 (NES)。NLS 或 NES 的改变影响 INPP5F 的定位及其下游分子的表达。此外，我们发现 INPP5F 通过 NES 和 NLS 分别与输出蛋白和导入蛋白相互作用，但与输出蛋白的相互作用更强，导致 INPP5F 在 HCC 中发生细胞质定位。
这些发现表明，INPP5F 通过易位机制发挥 HCC 中的癌基因作用，并激活 ASPH 介导的 Notch 信号通路。INPP5F 可能成为 HCC 患者的潜在治疗靶点。
