Gankyrin regulates cell signaling network

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.

Distinct ankyrin repeat subdomains control VAPYRIN locations and intracellular accommodation functions during arbuscular mycorrhizal symbiosis

Over 70% of vascular flowering plants engage in endosymbiotic associations with arbuscular mycorrhizal (AM) fungi. VAPYRIN (VPY) is a plant protein that is required for intracellular accommodation of AM fungi but how it functions is still unclear. VPY has a large ankyrin repeat domain with potential for interactions with multiple proteins. Here we show that overexpression of the ankyrin repeat domain results in a vpy-like phenotype, consistent with the sequestration of interacting proteins. We identify distinct ankyrin repeats that are essential for intracellular accommodation of arbuscules and reveal that VPY functions in both the cytoplasm and nucleus. VPY interacts with two kinases, including DOES NOT MAKE INFECTIONS3 (DMI3), a nuclear-localized symbiosis signaling kinase. Overexpression of VPY in a symbiosis-attenuated genetic background results in a dmi3 -like phenotype suggesting that VPY negatively influences DMI3 function. Overall, the data indicate a requirement for VPY in the nucleus and cytoplasm where it may coordinate signaling and cellular accommodation processes.

VAPYRIN is a plant protein required for symbiosis with arbuscular mycorrhizal fungi. Here the authors identify VAPYRIN domains that control subcellular targeting and protein-protein interactions and propose that VAPYRIN acts in the nucleus and cytoplasm to coordinate signaling and intracellular arbuscule accommodation.

Biological effects and regulation of IGFBP5 in breast cancer

The insulin-like growth factor receptor (IGF1R) pathway plays an important role in cancer progression. In breast cancer, the IGF1R pathway is linked to estrogen-dependent signaling. Regulation of IGF1R activity is complex and involves the actions of its ligands IGF1 and IGF2 and those of IGF-binding proteins (IGFBPs). Six IGFBPs are known that share the ability to form complexes with the IGFs, by which they control the bioavailability of these ligands. Besides, each of the IGFBPs have specific features. In this review, the focus lies on the biological effects and regulation of IGFBP5 in breast cancer. In breast cancer, estrogen is a critical regulator of IGFBP5 transcription. It exerts its effect through an intergenic enhancer loop that is part of the chromosomal breast cancer susceptibility region 2q35. The biological effects of IGFBP5 depend upon the cellular context. By inhibiting or promoting IGF1R signaling, IGFBP5 can either act as a tumor suppressor or promoter. Additionally, IGFBP5 possesses IGF-independent activities, which contribute to the complexity by which IGFBP5 interferes with cancer cell behavior.

Interaction between PSMD10 and GRP78 accelerates endoplasmic reticulum stress-mediated hepatic apoptosis induced by homocysteine

Background

The liver plays an important role in production and metabolism of homocysteine (Hcy), which has been reported to be involved in liver injury. In our previous work, we confirm that Hcy can induce liver injury by activating endoplasmic reticulum (ER) stress. However, the underlying mechanisms remain largely unknown.

Results

In present study, we established the Hcy-induced liver injury model by feeding cbs^+/− mice with high methionine diet, and found that a considerable mass of disordered arrangement of hepatocytes and enlarged space between hepatocytes were frequently occurred in the liver of cbs^+/− mice, accompanied with elevated expression levels of apoptosis-related proteins. In addition, Hcy could activate ER stress both in cbs^+/− mice and hepatocytes. Mechanistically, Hcy promoted the expression levels of proteasome 26S subunit non-ATPase 10 (PSMD10) in hepatocytes; and the expression of ER stress indicators and apoptosis-associated proteins were significantly suppressed when PSMD10 was silenced in hepatocytes under Hcy treatment. Moreover, bioinformatics analysis and luciferase reporter assay demonstrated that PSMD10 was a target gene of miR-212-5p. Consistently, miR-212-5p overexpression could inhibit ER stress-mediated apoptosis of hepatocytes under Hcy treatment. With the help of co-immunoprecipitation assay, we identified that the interaction between PSMD10 and GRP78 accelerated ER stress-mediated hepatic apoptosis induced by Hcy.

Conclusions

Our findings indicate that miR-212-5p directly targets PSMD10 and subsequently activates ER stress to promote Hcy-induced apoptosis of hepatocytes. We propose that endogenous PSMD10 physically interacts with GRP78 to regulate ER stress. Our study may provide the therapeutic target for the liver injury induced by Hcy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-021-00455-z.

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.

Exploring the proteasome system: A novel concept of proteasome inhibition and regulation

The proteasome is a well-identified therapeutic target for cancer treatment. It acts as the main protein degradation system in the cell and degrades key mediators of cell growth, survival and function. The term "proteasome" embraces a whole family of distinct complexes, which share a common proteolytic core, the 20S proteasome, but differ by their attached proteasome activators. Each of these proteasome complexes plays specific roles in the control of cellular function. In addition, distinct proteasome interacting proteins regulate proteasome activity in subcellular compartments and in response to cellular signals. Proteasome activators and regulators may thus serve as building blocks to fine-tune proteasome function in the cell according to cellular needs. Inhibitors of the proteasome, e.g. the FDA approved drugs Velcade™, Kyprolis™, Ninlaro™, inactivate the catalytic 20S core and effectively block protein degradation of all proteasome complexes in the cell resulting in inhibition of cell growth and induction of apoptosis. Efficacy of these inhibitors, however, is hampered by their pronounced cytotoxic side-effects as well as by the emerging development of resistance to catalytic proteasome inhibitors. Targeted inhibition of distinct buiding blocks of the proteasome system, i.e. proteasome activators or regulators, represents an alternative strategy to overcome these limitations. In this review, we stress the importance of the diversity of the proteasome complexes constituting an entire proteasome system. Our building block concept provides a rationale for the defined targeting of distinct proteasome super-complexes in disease. We thereby aim to stimulate the development of innovative therapeutic approaches beyond broad catalytic proteasome inhibition.

LncRNA DANCR Promotes Sorafenib Resistance via Activation of IL-6/STAT3 Signaling in Hepatocellular Carcinoma Cells

Background

Hepatocellular carcinoma (HCC) is one of the major malignancies and the second most common cause of cancer-related death worldwide. Sorafenib, an approved first-line systematic treatment agent for HCC, is capable to effectively improve the survival of patients with advanced HCC. The long-noncoding RNA (lncRNA) differentiation antagonizing non-protein coding RNA (DANCR) has been reported to exert oncogenic functions in several kinds of human cancers. However, the role of lncRNA DANCR in sorafenib resistance in HCC remains unknown.

Methods

The expression levels of DANCR in HCC tissues were detected by qRT-PCR. DANCR overexpression and knockdown models were established and utilized to investigate the functional role of DANCR on sorafenib resistance in HCC cells. The MS2-binding sequences-MS2-binding protein–based RNA immunoprecipitation assay, RNA pull-down and luciferase reporter assay was used to detect the association between DANCR and PSMD10 mRNA. The activation of DANCR transcription mediated by STAT3 was assessed by luciferase reporter and chromatin immunoprecipitation assays.

Results

We found that DANCR was significantly overexpressed in HCC tissues and associated with prognosis of HCC patients. Overexpression and knockdown experiments demonstrated that DANCR promoted sorafenib resistance in HCC cells in vitro and in vivo. Mechanistically, the role of DANCR relied largely on the association with PSMD10. DANCR stabilized PSMD10 mRNA through blocking the repressing effect of several microRNAs on PSMD10. Besides, DANCR activated IL-6/STAT3 signaling via PSMD10. Furthermore, we revealed that DANCR transcription was enhanced by the activation of IL-6/STAT3 signaling, indicating a positive feedback loop of DANCR and IL-6/STAT3 signaling.

Conclusion

Collectively, our study is the first to elucidate the mechanism of DANCR-mediated sorafenib resistance via PSMD10-IL-6/STAT3 signaling axis, which provides a promising target for developing new therapeutic strategy for sorafenib tolerance of HCC.

Role of a 19S Proteasome Subunit- PSMD10Gankyrin in Neurogenesis of Human Neural Progenitor Cells

PSMD10^Gankyrin, a proteasome assembly chaperone, is a widely known oncoprotein which aspects many hall mark properties of cancer. However, except proteasome assembly chaperon function its role in normal cell function remains unknown. To address this issue, we induced PSMD10^Gankyrin overexpression in HEK293 cells and the resultant large-scale changes in gene expression profile were analyzed. We constituted networks from microarray data of these differentially expressed genes and carried out extensive topological analyses. The overrecurring yet consistent theme that appeared throughout analysis using varied network metrics is that all genes and interactions identified as important would be involved in neurogenesis and neuronal development. Intrigued we tested the possibility that PSMD10^Gankyrin may be strongly associated with cell fate decisions that commit neural stem cells to differentiate into neurons. Overexpression of PSMD10^Gankyrin in human neural progenitor cells facilitated neuronal differentiation via β-catenin Ngn1 pathway. Here for the first time we provide preliminary and yet compelling experimental evidence for the involvement of a potential oncoprotein – PSMD10^Gankyrin, in neuronal differentiation.

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.

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.

Proteasome dysregulation in human cancer: implications for clinical therapies

Cancer cells show heightened dependency on the proteasome for their survival, growth, and spread. Proteasome dysregulation is therefore commonly selected in favor of the development of many types of cancer. The vast abnormalities in a cancer cell, on top of the complexity of the proteasome itself, have enabled a plethora of mechanisms gearing the proteasome to the oncogenic process. Here, we use selected examples to highlight some general mechanisms underlying proteasome dysregulation in cancer, including copy number variations, transcriptional control, epigenetic regulation, and post-translational modifications. Research in this field has greatly advanced our understanding of proteasome regulation and will shed new light on proteasome-based combination therapies for cancer treatment.

Gankyrin: a novel promising therapeutic target for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is known as fifth common malignancies and third common cause of cancer-related death worldwide. The identification of various mechanisms which are involved in hepatocarcinogenesis contributes in finding a variety of cellular and molecular targets for HCC diagnosis, prevention and therapy. Among various identified targets in HCC pathogenesis, Gankyrin is a crucial oncoprotein that is up-regulated in HCC and plays a pivotal role in the initiation and progression of the HCC. Oncogenic role of Gankyrin has been found to stem from inhibition of two ubiquitous tumour suppressor proteins, retinoblastoma protein (pRb) and P53, and also modulation of several vital cellular signalling pathways including Wnt/β-Catenin, NF-κB, STAT3/Akt, IL-1β/IRAK-1 and RhoA/ROCK. As a result, Gankyrin can be considered as a potential candidate for diagnosis and treatment of HCC. In this review, we summarized the physiological function and the significant role of Gankyrin as an important therapeutic target in HCC.

Inducible liver-specific overexpression of gankyrin in zebrafish results in spontaneous intrahepatic cholangiocarcinoma and hepatocellular carcinoma formation

Liver cancer is the second leading cause of death worldwide. As such, establishing animal models of the disease is important for both basic and translational studies that move toward developing new therapies. Gankyrin is a critical oncoprotein in the genetic control of liver pathology. In order to evaluate the oncogenic role of gankyrin without cancer cell inoculation and drug treatment, we overexpressed gankyrin under the control of the fabp10a promoter. A Tet-Off system was used to drive expression in hepatocytes. At seven to twelve months of age, gankyrin transgenic fish spontaneously incurred persistent hepatocyte damage, steatosis, cholestasis, cholangitis, fibrosis and hepatic tumors. The tumors were both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). ICC is the second most frequent primary liver cancer in human patients and the first to develop in this tumor model. We further investigated the role of complement C3, a central molecule of the complement system, and found the expression levels of both in mRNA and protein are decreased during tumorigenesis. Together, these findings suggest that gankyrin can promote malignant transformation of liver cells in the context of persistent liver injury. This transformation may be related to compensatory proliferation and the inflammatory microenvironment. The observed decrease in complement C3 may allow transforming cells to escape coordinated induction of the immune response. Herein, we demonstrate an excellent zebrafish model for liver cancers that will be useful for studying the molecular mechanisms of tumorgenesis.

Gankyrin as a potential therapeutic target for cancer

Gankyrin is an oncoprotein that plays a central role in the development of cancer. Although researchers have increasingly focused on the relationships of gankyrin with carcinogenesis, metastasis and prognosis of different cancers, the molecular mechanisms are still unclear. In recent years, several interacting partners of gankyrin and cell signaling pathways regulated by gankyrin have been elucidated. In addition, accumulating evidence has indicated the contribution of microRNAs to regulating gankyrin expression in tumor cells. In this review, we summarize the major known roles of gankyrin in cancer cells and highlight the potential clinical relevance of targeting gankyrin. Graphical abstract ᅟ.

MicroRNA-1254 inhibits the migration of colon adenocarcinoma cells by targeting PSMD10

OBJECTIVE

MicroRNA-1254 (miR-1254) has not been studied in colorectal cancer (CRC) to date. This study aimed to investigate the inhibitory mechanism of miR-1254 in CRC tumorigenesis.

METHODS

MiR-1254 expression was examined using real-time polymerase chain reaction in CRC and adjacent non-tumorous tissues. The correlation between miR-1254 expressions and proliferation and migration of cancer cells was determined using the CCK-8 and transwell assays. RNA sequencing was used to identify differentially expressed genes downstream from miR-1254. A luciferase reporter assay was used to confirm the direct interaction between miR-1254 and its predicted target gene, PSMD10. Moreover, PSMD10 was either overexpressed or silenced in colon carcinoma cells overexpressing miR-1254 to determine whether their interaction contributed to CRC migration and epithelial-mesenchymal transition (EMT).

RESULTS

Significantly lower miR-1254 expressions were observed in CRC tissues than in adjacent non-tumorous tissues. Exogenous miR-1254 expression suppressed the migration of colon carcinoma cell lines SW1116 and HCT116. RNA sequencing and luciferase assays revealed that miR-1254 directly binded to the 3'-untranslated region of PSMD10, an important regulator of EMT and cell migration. PSMD10 knockdown inhibited EMT and colon cancer cell migration, whereas PSMD10 overexpression reversed the inhibition of EMT and cell migration caused by miR-1254.

CONCLUSION

MiR-1254 may act as a tumor suppressor in CRC and may inhibit CRC migration by directly targeting PSMD10 to suppress the EMT process.