WD repeat domain 76 predicts poor prognosis in lower grade glioma and provides an original target for immunotherapy

BACKGROUND

The WD40 repeat (WDR) domain provides scaffolds for numerous protein-protein interactions in multiple biological processes. WDR domain 76 (WDR76) has complex functionality owing to its diversified interactions; however, its mechanism in LGG has not yet been reported.

METHODS

Transcriptomic data from public databases were multifariously analyzed to explore the role of WDR76 in LGG pathology and tumor immunity. Laboratory experiments were conducted to confirm these results.

RESULTS

The results first confirmed that high expression of WDR76 in LGG was not only positively associated with clinical and molecular features of malignant LGG, but also served as an independent prognostic factor that predicted shorter survival in patients with LGG. Furthermore, high expression of WDR76 resulted in the upregulation of oncogenes, such as PRC1 and NUSAP1, and the activation of oncogenic mechanisms, such as the cell cycle and Notch signaling pathway. Finally, WDR76 was shown to be involved in LGG tumor immunity by promoting the infiltration of immune cells, such as M2 macrophages, and the expression of immune checkpoints, such as PDCD1 (encoding PD-1).

CONCLUSIONS

This study shows for the first time the diagnostic and prognostic value of WDR76 in LGG and provides a novel personalized biomarker for future targeted therapy and immunotherapy. Thus, WDR76 may significantly improve the prognosis of patients with LGG.

WDR76 regulates 5-fluorouracil sensitivity in colon cancer via HRAS

BACKGROUND

WD repeat domain 76 (WDR76) has been reported in multiple tumors, while without relation to chemotherapy resistance. 5-fluorouracil (5-FU) is widely adopted in treating colon cancer. However, the resistance of WDR76 and 5-FU in colon cancer remains unclear.

METHODS

Limma package in R software was employed to analyze the differentially expressed genes. Western blot or quantitative real-time PCR (qRT-PCR) were run to assessed the gene expression. The cytotoxic effect was determined according to cell viability assay, colony formation assay in vitro. Cell apoptosis was assayed using flow cytometry. GSEA analysis was performed to identify pathways related to the target gene. Xenografted mice model was employed to evaluate the tumor growth.

RESULTS

Bioinformatic analysis revealed the higher expression of WDR76 in 5-FU sensitive colon cancer cells compared to resistant colon cancer cells, accompanied by the decreased mRNA expression of WDR76 in 5-FU resistant colon cancer cells. The overexpressed WDR76 resulted in the apoptosis and the downregulated colony numbers in 5-FU resistant colon cancer cells, leading to the elevated sensitivity of 5-FU. Meanwhile, knockdown of WDR76 enhances the resistance of 5-FU in colon cancer both in vitro and vivo, which was reversed by a specific inhibitor of HRAS, Kobe006. An important molecular mechanism of 5-FU resistance lies the degradation of HRAS induced by WDR76.

CONCLUSION

Our findings demonstrated a role of WDR76 as a promising target for reversing the resistance of colon cancer to 5-FU.

The correlation of WDR76 expression with survival outcomes and immune infiltrates in lung adenocarcinoma

Background

WD repeat domain 76 (WDR76) is a predicted member of the WD40-repeat-containing domain superfamily and possibly involves in various biological processes, but its function in cancers is poorly characterized. This study aimed to evaluate the role of WDR76 in the prognosis and immune infiltrates of lung adenocarcinoma (LUAD).

Methods

WDR76 expressions in LUAD tissues and normal tissues were primarily compared by The Cancer Genome Atlas (TCGA) database, and were validated in cohorts from Gene Expression Omnibus (GEO) database. The associations between WDR76 expression and clinicopathologic characteristics were analyzed. Kaplan–Meier and Cox regression analyses were performed to determine the impact of WDR76 expression on survival outcomes. The protein interaction network of WDR76 was built using STRING website. TIMER and GEPIA databases were used to investigate the correlation between WDR76 expression and immune infiltrates.

Results

WDR76 expression was elevated in LUAD (P < 0.001) and high WDR76 expression was associated with advanced N stage, M stage and pathologic stage. Expectedly, high WDR76 expression significantly correlated with poor survival outcomes and was the independent risk factor for overall survival (OS) (HR 1.468, 95% CI [1.031–2.089], P = 0.033) and disease specific survival (DSS) (HR 1.764, 95% CI [1.095–2.842], P = 0.020). DDB1 and LSH were the important proteins interacting with WDR76. WDR76 expression correlated with CD8+ T cells presence and was also positively associated with levels of inhibitory receptors.

Conclusion

WDR76 expression was involved in the regulation of immune infiltrates and had predictive value for prognosis in LUAD.

Biochemical Reduction of the Topology of the Diverse WDR76 Protein Interactome

A hub protein in protein interaction networks will typically have a large number of diverse interactions. Determining the core interactions and the function of such a hub protein remains a significant challenge in the study of networks. Proteins with WD40 repeats represent a large class of proteins that can be hub proteins. WDR76 is a poorly characterized WD40 repeat protein with possible involvement in DNA damage repair, cell-cycle progression, apoptosis, gene expression regulation, and protein quality control. WDR76 has a large and diverse interaction network that has made its study challenging. Here we rigorously carry out a series of affinity purification coupled to mass spectrometry (AP-MS) analyses to map out the WDR76 interactome through different biochemical conditions. We apply AP-MS analysis coupled to size-exclusion chromatography to resolve WDR76-based protein complexes. Furthermore, we also show that WDR76 interacts with the CCT complex via its WD40 repeat domain and with DNA-PK-KU, PARP1, GAN, SIRT1, and histones outside of the WD40 domain. An evaluation of the stability of WDR76 interactions led to focused and streamlined reciprocal analyses that validate the interactions with GAN and SIRT1. Overall, the approaches used to study WDR76 would be valuable to study other proteins containing WD40 repeat domains, which are conserved in a large number of proteins in many organisms.

WDR76 degrades RAS and suppresses cancer stem cell activation in colorectal cancer

Background

Stabilization of RAS is a key event for the hyper-activation of Wnt/β-catenin signaling and activation of cancer stem cell (CSC) in colorectal cancer (CRC). WD Repeat protein 76 (WDR76) mediates the polyubiquitination-dependent degradation of RAS in hepatocellular carcinoma (HCC). We investigated whether WDR76 destabilizes RAS and acts as a tumor suppressor inhibiting CSC activation in CRC.

Methods

We generated mice with deletion of Wdr76 (Wdr76^−/−) and crosses of Wdr76^−/− with Apc^Min/+ (Wdr76^−/−; Apc^Min/+) and compared them with wildtype mice (Wdr76^+/+) and Apc^Min/+ mice (Wdr76^+/+; Apc^Min/+), respectively. Intestinal crypt lengthening, tumorigenesis and CSC activation were analyzed by histology, immunohistochemistry, and immunoblotting. CRC cell line was engineered to stably express or knockdown WDR76 or control vector and was analyzed after spheroid culture.

Results

Wdr76^−/− mice, with increased Ras level, displayed crypt elongation and hyper-proliferation. Wdr76^−/−; Apc^Min/+ mice developed more tumors with bigger sizes than Apc^Min/+ mice and their tumors showed increased proliferation and CSC activation with elevated RAS and β-catenin levels. In CRC cells, overexpression or knockdown of WDR76 decreased or increased the numbers and sizes of CRC spheroids with inhibition or activation of CSC markers, respectively. In human CRC, lower level of WDR76 was associated with poor patient survival.

Conclusions

In analyses of mice with deletion of Wdr76 and CRC spheroids, we found that RAS stability plays important roles in tumorigenesis by affecting proliferation and CSC activation. Our results suggest that destabilization of RAS by WDR76 is a potential strategy for targeting malignant CRC involving CSC activation.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0403-x) contains supplementary material, which is available to authorized users.

EGLN1/c-Myc Induced Lymphoid-Specific Helicase Inhibits Ferroptosis through Lipid Metabolic Gene Expression Changes

Ferroptosis is a newly discovered form of non-apoptotic cell death in multiple human diseases. However, the epigenetic mechanisms underlying ferroptosis remain poorly defined. First, we demonstrated that lymphoid-specific helicase (LSH), which is a DNA methylation modifier, interacted with WDR76 to inhibit ferroptosis by activating lipid metabolism-associated genes, including GLUT1, and ferroptosis related genes SCD1 and FADS2, in turn, involved in the Warburg effect. WDR76 targeted these genes expression in dependent manner of LSH and chromatin modification in DNA methylation and histone modification. These effects were dependent on iron and lipid reactive oxygen species. We further demonstrated that EGLN1 and c-Myc directly activated the expression of LSH by inhibiting HIF-1α. Finally, we demonstrated that LSH functioned as an oncogene in lung cancer in vitro and in vivo. Therefore, our study elucidates the molecular basis of the c-Myc/EGLN1-mediated induction of LSH expression that inhibits ferroptosis, which can be exploited for the development of therapeutic strategies targeting ferroptosis for the treatment of cancer.