Immortalization-upregulated protein promotes pancreatic cancer progression by regulating NPM1/FHL1-mediated cell-cycle-checkpoint protein activity

Qiankun Luo,Yanfeng Pan,Qiang Fu,Xu Zhang,Shuai Zhou,Pengfei Yu,Huiyuan Tian,Pan Liu,Song Chen,Hongwei Zhang,Tao Qin

doi:10.1007/s10565-022-09695-4

Abstract

Immortalization-upregulated protein (IMUP) plays a vital role in cell proliferation and tumor progression. However, its role in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here, we select IMUP as an alternative gene based on GeneChip analysis of clinical PDAC tissues and transcriptome data from The Cancer Genome Atlas. IMUP expression is upregulated in PDAC tumor tissues. Moreover, high IMUP expression correlates with poor prognosis, while IMUP depletion inhibits PDAC cell proliferation and colony formation capacity in vitro, and decreases xenograft tumor growth in vivo. IMUP downregulation leads to cell-cycle arrest in the S phase. IMUP knockdown increases the expression of four-and-a-half LIM domain protein 1 (FHL1), which regulates the phosphorylation of cell division cycle 25A (CDC25A) by cycle checkpoint kinase 1 (CHK1) and promotes cytoplasmic distribution of CDC25A by interaction with 14–3-3ξ. Furthermore, FHL1 knockdown restores the effects induced by IMUP depletion. Liquid chromatography tandem mass spectrometry and immunoprecipitation analysis further show that IMUP interacts directly with nucleophosmin (NPM1) and enhances its stability. DNA methylation sequencing shows that FHL1 promoter methylation decreases when IMUP is downregulated. Overexpression of NPM1 can increase the methylation level of FHL1, thereby decreasing its expression. Our study provides a novel perspective on IMUP/NPM1/FHL1-mediated cell-cycle arrest by regulating CDC25A phosphorylation in PDAC. These findings may provide a new therapeutic target for PDAC.Graphical abstract

Highlights

Pancreatic ductal adenocarcinoma (PDAC) is a malignant tumor with poor prognosis (Siegel et al 2019)
Immortalization-upregulated protein (IMUP) is upregulated in PDAC and associated with poor prognosis
◂Fig. 1 IMUP is upregulated in PDAC and correlates with poor prognosis. a IMUP was selected from the intersection of differentially expressed genes (DEGs) from GeneChip, Differentially expressed genes (DEGs) from The Cancer Genome Atlas (TCGA), and survival-related genes (SRGs) from TCGA. b IMUP expression differs between different simplified tumor stages (P < 0.0001) and is negatively correlated with overall survival (OS)

Summary

Introduction

Pancreatic ductal adenocarcinoma (PDAC) is a malignant tumor with poor prognosis (Siegel et al 2019). Various hallmark capacities of cancer have been recognized (Hanahan and Weinberg, 2011), no effective pharmacotherapeutic or chemotherapeutic strategies exist for PDAC. Among the ten cancer hallmarks, one of the most important is sustaining cell proliferation capability (Hanahan and Weinberg, 2011). The abnormal regulation of cell-cycle checkpoints greatly contributes to malignant cell proliferation. DNA damage caused by ionizing radiation, chemicals, and drugs typically induces cell-cycle checkpoint arrest, providing the opportunity for increased DNA repair (Murakami and Nurse, 2000). Cancer cells acquire the ability to circumvent cell-cycle checkpoints by activating intracellular signaling pathways, thereby, facilitating their continual grow. Many researchers focused on the regulation of G1 and G2 checkpoints as prominent cellcycle arrests were more readily observed in the G1 and G2 phases. The S-phase checkpoint has a more significant role in maintaining genetic stability than either G1 or G2 phases (Bartek et al 2004)

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