Gankyrin as a potential therapeutic target for cancer

Synthesis and evaluation of 2,5-substituted pyrimidines as small-molecule gankyrin binders

Background: Gankyrin is an ankyrin-repeat protein that promotes cell proliferation, tumor development and cancer progression when overexpressed. Aim: To design and synthesize a novel series of gankyrin-binding small molecules predicated on a 2,5-pyrimidine scaffold. Materials & methods: The synthesized compounds were evaluated for their antiproliferative activity, ability to bind gankyrin and effects on cell cycle progression and the proteasomal degradation pathway. Results: Compounds 188 and 193 demonstrated the most potent antiproliferative activity against MCF7 and A549 cells, respectively. Both compounds also demonstrated the ability to effectively bind gankyrin, disrupt proteasomal degradation and inhibit cell cycle progression. Conclusion: The 2,5-pyrimidine scaffold exhibits a novel and promising strategy for binding gankyrin and inhibiting cancer cell proliferation.

Genetically incorporated crosslinkers reveal NleE attenuates host autophagy dependent on PSMD10

Autophagy acts as a pivotal innate immune response against infection. Some virulence effectors subvert the host autophagic machinery to escape the surveillance of autophagy. The mechanism by which pathogens interact with host autophagy remains mostly unclear. However, traditional strategies often have difficulty identifying host proteins that interact with effectors due to the weak, dynamic, and transient nature of these interactions. Here, we found that Enteropathogenic Escherichia coli (EPEC) regulates autophagosome formation in host cells dependent on effector NleE. The 26S Proteasome Regulatory Subunit 10 (PSMD10) was identified as a direct interaction partner of NleE in living cells by employing genetically incorporated crosslinkers. Pairwise chemical crosslinking revealed that NleE interacts with the N-terminus of PSMD10. We demonstrated that PSMD10 homodimerization is necessary for its interaction with ATG7 and promotion of autophagy, but not necessary for PSMD10 interaction with ATG12. Therefore, NleE-mediated PSMD10 in monomeric state attenuates host autophagosome formation. Our study reveals the mechanism through which EPEC attenuates host autophagy activity.

LMX1B-associated gankyrin expression predicts poor prognosis in glioma patients

OBJECTIVE

To explore the potential of the transcription factor LMX1B and downstream gankyrin as prognostic biomarkers of glioma.

METHODS

The expression levels of gankyrin and LMX1B were detected in 52 normal brain specimens and 339 glioma specimens. Correlations of gankyrin and LMX1B expression levels with pathological stages and clinical characteristics were statistically analyzed. Furthermore, the binding of LMX1B to the gankyrin promoter was evaluated using ALGGEN PROMO.

RESULTS

Levels of LMX1B and gankyrin were significantly increased in tumor tissue, and were significantly associated with advanced glioma grade and poor survival. Compared with gankyrin- and LMX1B-negative glioma, the mean survival of patients with higher gankyrin and LMX1B expression was significantly reduced, from 83.46 to 18.87 months and from 63.79 to 18.29 months, respectively. Furthermore, LMX1B had a moderate positive correlation with gankyrin expression (Pearson's r = 0.650), and it was also found to act as a transcription factor with NF-κB and E47 on the gankyrin promoter.

CONCLUSIONS

Increased expression of LMX1B and gankyrin has independent prognostic value in glioma patients. The transcription factor LMX1B may have an upstream role in the mechanism of action.

Gankyrin promotes osteosarcoma tumorigenesis by forming a positive feedback loop with YAP

BACKGROUND

Although gankyrin has been identified as a vital regulator of tumorigenesis, its role and regulatory mechanism in osteosarcoma (OS) remain unclear.

METHODS

QRT-PCR, western blot and IHC staining were conducted to detect the expression of gankyrin in OS. Pearson's χ² test was adopted to examine the associations between gankyrin expression and clinicopathologic characteristics. Kaplan-Meier method was used to investigate the relationship between gankyrin expression and overall survival of patients with OS. Next, a series of in vitro and in vivo assays were performed to determine the positive feedback loop between gankyrin and YAP in OS.

RESULTS

We first reported that gankyrin is upregulated in human OS specimens and cell lines and predicts OS progression and poor prognosis. Furthermore, we demonstrated that gankyrin protects miR-200a-mediated yes-associated protein (YAP) downregulation through p53 and establishes a positive feedback loop to regulate YAP signaling in U2OS and MG63 cells. Intriguingly, gankyrin interacts with YAP to promote OS cell growth in vitro. In addition, our results showed that gankyrin promotes OS tumor growth and regulates YAP levels in vivo. Notably, we also observed a positive correlation between gankyrin and YAP expression in human OS tissues, and co-upregulation of gankyrin and YAP indicated a poor prognosis.

CONCLUSIONS

Our results identify that gankyrin acts as an oncogene in OS by forming a positive feedback loop with YAP, and disrupting the gankyrin-YAP regulation may be beneficial for controlling OS tumorigenesis.

Small-Molecule Inhibitors of the Proteasome's Regulatory Particle

Cells need to synthesize and degrade proteins consistently. Maintaining a balanced level of protein in the cell requires a carefully controlled system and significant energy. Degradation of unwanted or damaged proteins into smaller peptide units can be accomplished by the proteasome. The proteasome is composed of two main subunits. The first is the core particle (20S CP), and within this core particle are three types of threonine proteases. The second is the regulatory complex (19S RP), which has a myriad of activities including recognizing proteins marked for degradation and shuttling the protein into the 20S CP to be degraded. Small-molecule inhibitors of the 20S CP have been developed and are exceptional treatments for multiple myeloma (MM). 20S CP inhibitors disrupt the protein balance, leading to cellular stress and eventually to cell death. Unfortunately, the 20S CP inhibitors currently available have dose-limiting off-target effects and resistance can be acquired rapidly. Herein, we discuss small molecules that have been discovered to interact with the 19S RP subunit or with a protein closely associated with 19S RP activity. These molecules still elicit their toxicity by preventing the proteasome from degrading proteins, but do so through different mechanisms of action.

The Oncoprotein Gankyrin/PSMD10 as a Target of Cancer Therapy

Gankyrin (also called PSMD10, p28, or p28^GANK) is a crucial oncoprotein that is upregulated in various cancers and assumed to play pivotal roles in the initiation and progression of tumors. Although the in vitro function of gankyrin is relatively well characterized, its role in vivo remains to be elucidated. We have investigated the function of gankyrin in vivo by producing mice with liver parenchymal cell-specific gankyrin ablation (Alb-Cre;gankyrin^f/f) and gankyrin deletion both in liver parenchymal and in non-parenchymal cells (Mx1-Cre;gankyrin^f/f). Gankyrin deficiency both in non-parenchymal cells and parenchymal cells, but not in parenchymal cells alone, reduced STAT3 activity, interleukin-6 production, and cancer stem cell marker expression, leading to attenuated tumorigenic potential in the diethylnitrosamine hepatocarcinogenesis model. Essentially similar results were obtained by analyzing mice with intestinal epithelial cell-specific gankyrin ablation (Villin-Cre;Gankyrin^f/f) and gankyrin deletion both in myeloid and epithelial cells (Mx1-Cre;Gankyrin^f/f) in the colitis-associated cancer model. Clinically, gankyrin expression in the tumor microenvironment was negatively correlated with progression-free survival in patients undergoing treatment with Sorafenib for hepatocellular carcinomas. These findings indicate important roles played by gankyrin in non-parenchymal cells as well as parenchymal cells in the pathogenesis of liver cancers and colorectal cancers, and suggest that by acting both on cancer cells and on the tumor microenvironment, anti-gankyrin agents would be promising as therapeutic and preventive strategies against various cancers, and that an in vitro cell culture models that incorporate the effects of non-parenchymal cells and gankyrin would be useful for the study of human cell transformation.

Gankyrin is a novel biomarker for disease progression and prognosis of patients with renal cell carcinoma

BACKGROUND

In the clinic, how to stratify renal cell carcinoma (RCC) patients with different risks and to accurately predict their prognostic outcome remains a crucial issue. In this study, we assessed the expression and prognostic value of gankyrin in RCC patients.

METHODS

The expression of gankyrin was examined in public databases and validated in specimens from two independent centers. The clinical practice and disease correlation of gankyrin in RCC were evaluated in RCC patients, various cell lines and an orthotopic RCC model.

FINDINGS

Upregulation of gankyrin expression in RCC was corroborated in two independent cohorts. High gankyrin expression positively associated with disease progression and metastasis of RCC patients. A positive correlation between gankyrin and sunitinib-resistance was also observed in RCC cell lines and in an orthotopic RCC model. Kaplan-Meier analysis revealed that patients with higher gankyrin expression presented worse prognosis of RCC patients in the two cohorts. Gankyrin served as an independent prognostic factor for RCC patients even after multivariable adjustment by clinical variables. Time-dependent AUC and Harrell's c-index analysis presented that the incorporation of the gankyrin classifier into the current clinical prognostic parameters such as TNM stage, Fuhrman nuclear grade or SSIGN score achieved a greater accuracy than without it in predicting prognosis of RCC patients. All results were confirmed in randomized training and validation sets from the two patient cohorts.

INTERPRETATION

Gankyrin can serve as a reliable biomarker for disease progression and for prognosis of RCC patients. Combining gankyrin with the current clinical parameters may help patient management. FUND: National Natural Science Foundation of China (No. 81773154, 81772747 and 81301861), Medical Discipline Construction Project of Pudong New Area Commission of Health and Family Planning (PWYgf2018-03), the Shanghai Medical Guidance (Chinese and Western Medicine) Science and Technology Support Project (No. 17411960200), Outstanding Leaders Training Program of Pudong Health Bureau of Shanghai (No. PWR12016-05).

Gankyrin drives metabolic reprogramming to promote tumorigenesis, metastasis and drug resistance through activating β-catenin/c-Myc signaling in human hepatocellular carcinoma

Gankyrin plays important roles in tumorigenicity and metastasis of hepatocellular carcinoma (HCC). We have for the first time investigated the effects of Gankyrin on glycolysis and glutaminolysis both in vitro and in vivo, including in patient-derived xenografts. We reported Gankyrin increases glucose consumption, lactate production, glutamine consumption and glutamate production in HCC through upregulating the expression of the transporters and enzymes involved in glycolysis and glutaminolysis, including HK2, GLUT1, LDHA, PKM2, ASCT2 and GLS1. We further demonstrated that Gankyrin drives glycolysis and glutaminolysis through upregulating c-Myc via activating β-catenin signaling. Importantly, we found c-Myc mediated metabolic reprogramming might contribute to the tumorigenicity, metastasis and drug resistance induced by Gankyrin. c-Myc inhibitor synergizes with Sorafenib or Regorafenib to suppress HCC PDX tumors with high Gankyrin levels. We detected a significant correlation between Gankyrin and β-catenin expression levels in a cohort of HCC biopsies, and combination of these two parameters is a more powerful predictor of poor prognosis. Collectively, our results uncovered that Gankyrin functions as an essential regulator in glycolysis and glutaminolysis via activation of β-catenin/c-Myc to promotes tumorigenesis, metastasis and drug resistance in human HCC.

Gankyrin Drives Malignant Transformation of Gastric Cancer and Alleviates Oxidative Stress via mTORC1 Activation

Gastric cancer, as a malignant epithelial tumor, is a major health threat leading to poor overall survival and death. It is usually diagnosed at an advanced stage due to asymptomatic or only nonspecific early symptoms. The present study demonstrated that gankyrin contributes to the early malignant transformation of gastric cancer and can be selected to predict the risk of gastric cancer in those patients harboring the precancerous lesions (dysplasia and intestinal metaplasia). In addition, a new insight into gastric cancer was provided, which stated that gankyrin alleviates oxidative stress via mTORC1 pathway activation. It can potentiate the mTORC1 by PGK1-AKT signaling that promotes the tumor process, and this phenomenon is not completely consistent with the previous report describing colorectal cancer.

Transcriptomic analysis reveals the underlying pro-malignant functions of Gankyrin for colorectal cancer via affecting tumor necrosis factor pathway

BACKGROUND

Recently increasing evidence had indicated Gankyrin play an important role for the development and progression of colorectal cancer (CRC). However, its function mechanisms remain unclear. The goal of this study was to further illuminate the roles of Gankyrin in CRC using microarray data.

METHODS

The microarray data of CRC was extracted from the Gene Expression Omnibus (GEO) database under the accession number GSE44029. Differentially expressed genes (DEGs) were identified using the LIMMA method, and then protein-protein interaction (PPI) network was constructed to screen crucial genes associated with Gankyrin. GO and KEGG pathway enrichment analysis were performed to investigate the underlying functions of DEGs using DAVID tool.

RESULTS

A total of 712 genes were identified as DEGs, including 15 upregulated genes and 697 downregulated genes. Go enrichment analysis indicated that Gankyrin was involved in tumor necrosis factor-mediated signaling pathway. A PPI network including 586 nodes and 654 edges was constructed, in which BIRC3 and PSMB9 were demonstrated to be the hub genes associated with Gankyrin.

CONCLUSION

Our present study preliminarily revealed that the pro-malignant effects of Gankyrin in CRC cells may be mediated by affecting TNF signaling pathway via changing the expression of the crucial enriched genes (BIRC3 and PSMB9).

PARP1 activation increases expression of modified tumor suppressors and pathways underlying development of aggressive hepatoblastoma

Hepatoblastoma (HBL) is a pediatric liver cancer that affects children under the age of three. Reduction of tumor suppressor proteins (TSPs) is commonly seen in liver cancer. However, in our studies we find that aggressive, chemo-resistant HBLs exhibit an elevation of TSPs. HBL patients with a classic phenotype have reduced TSP levels, but patients with aggressive HBL express elevated TSPs that undergo posttranslational modifications, eliminating their tumor suppression activities. Here we identify unique aggressive liver cancer domains (ALCDs) that are activated in aggressive HBL by PARP1-mediated chromatin remodeling leading to elevation of modified TSPs and activation of additional cancer pathways: WNT signaling and β-catenin. Inhibition of PARP1 blocks activation of ALCDs and normalizes expression of corresponding genes, therefore reducing cell proliferation. Our studies reveal PARP1 activation as a mechanism for the development of aggressive HBL, further suggesting FDA-approved PARP1 inhibitors might be used for treatment of patients with aggressive HBL.

Leila Valanejad et al. report increased expression of modified tumor suppressor proteins (TSPs) with loss of tumor suppressor activity in aggressive, chemotherapy-resistant hepatoblastoma. They find that TSP upregulation occurs via PARP1-mediated chromatin remodeling, leading to activation of multiple cancer-associated pathways.

Gankyrin Promotes Tumor-Suppressor Protein Degradation to Drive Hepatocyte Proliferation

Background & Aims

Uncontrolled liver proliferation is a key characteristic of liver cancer; however, the mechanisms by which this occurs are not well understood. Elucidation of these mechanisms is necessary for the development of better therapy. The oncogene Gankyrin (Gank) is overexpressed in both hepatocellular carcinoma and hepatoblastoma. The aim of this work was to determine the role of Gank in liver proliferation and elucidate the mechanism by which Gank promotes liver proliferation.

Methods

We generated Gank liver-specific knock-out (GLKO) mice and examined liver biology and proliferation after surgical resection and liver injury.

Results

Global profiling of gene expression in GLKO mice showed significant changes in pathways involved in liver cancer and proliferation. Investigations of liver proliferation after partial hepatectomy and CCl4 treatment showed that GLKO mice have dramatically inhibited proliferation of hepatocytes at early stages after surgery and injury. In control LoxP mice, liver proliferation was characterized by Gank-mediated reduction of tumor-suppressor proteins (TSPs). The failure of GLKO hepatocytes to proliferate is associated with a lack of down-regulation of these proteins. Surprisingly, we found that hepatic progenitor cells of GLKO mice start proliferation at later stages and restore the original size of the liver at 14 days after partial hepatectomy. To examine the proliferative activities of Gank in cancer cells, we used a small molecule, cjoc42, to inhibit interactions of Gank with the 26S proteasome. These studies showed that Gank triggers degradation of TSPs and that cjoc42-mediated inhibition of Gank increases levels of TSPs and inhibits proliferation of cancer cells.

Conclusions

These studies show that Gank promotes hepatocyte proliferation by elimination of TSPs. This work provides background for the development of Gank-mediated therapy for the treatment of liver cancer. RNA sequencing data can be accessed in the NCBI Gene Expression Omnibus: GSE104395.

Various Mechanisms Involve the Nuclear Factor (Erythroid-Derived 2)-Like (NRF2) to Achieve Cytoprotection in Long-Term Cisplatin-Treated Urothelial Carcinoma Cell Lines

Therapeutic efficacy of cisplatin-based chemotherapy for advanced-stage urothelial carcinoma (UC) is limited by drug resistance. The nuclear factor (erythroid-derived 2)-like 2 (NRF2) pathway is a major regulator of cytoprotective responses. We investigated its involvement in cisplatin resistance in long-term cisplatin treated UC cell lines (LTTs). Expression of NRF2 pathway components and targets was evaluated by qRT-PCR and western blotting in LTT sublines from four different parental cells. NRF2 transcriptional activity was determined by reporter assays and total glutathione (GSH) was quantified enzymatically. Effects of siRNA-mediated NRF2 knockdown on chemosensitivity were analysed by viability assays, γH2AX immunofluorescence, and flow cytometry. Increased expression of NRF2, its positive regulator p62/SQSTM1, and elevated NRF2 activity was observed in 3/4 LTTs, which correlated with KEAP1 expression. Expression of cytoprotective enzymes and GSH concentration were upregulated in some LTTs. NRF2 knockdown resulted in downregulation of cytoprotective enzymes and resensitised 3/4 LTTs towards cisplatin as demonstrated by reduced IC₅₀ values, increased γH2AX foci formation, and elevated number of apoptotic cells. In conclusion, while LTT lines displayed diversity in NRF2 activation, NRF2 signalling contributed to cisplatin resistance in LTT lines, albeit in diverse ways. Accordingly, inhibition of NRF2 can be used to resensitise UC cells to cisplatin, but responses in patients may likewise be variable.