The oncoprotein gankyrin binds to MDM2/HDM2, enhancing ubiquitylation and degradation of p53

CDK4/6 inhibition initiates cell cycle arrest by nuclear translocation of RB and induces a multistep molecular response

CDK4/6 inhibitors are standard of care in the treatment of metastatic breast cancer. Treatment regimen consists of a combination with endocrine therapy, since their therapeutic efficacy as monotherapy in most clinical trials was rather limited. Thus, understanding the molecular mechanisms that underlie response to therapy might allow for the development of an improved therapy design. We analyzed the response to the CDK4/6 inhibitor palbociclib in bladder cancer cells over a 48-hour time course using RNA sequencing and identified a multi-step mechanism of response. We next translated these results to the molecular mechanism in bladder cancer cells upon PD treatment. The initial step is characterized by translocation of the RB protein into the nucleus by activation of importin α/β, a mechanism that requires the NLS sequence. In parallel, RB is proteolyzed in the cytoplasm, a process regulated by gankyrin and the SCF complex. Only hypophosphorylated RB accumulates in the nucleus, which is an essential step for an efficient therapy response by initiating G1 arrest. This might explain the poor response in RB negative or mutated patients. At later stages during therapy, increased expression of the MiT/TFE protein family leads to lysosomal biogenesis which is essential to maintain this response. Lastly, cancer cells either undergo senescence and apoptosis or develop mechanisms of resistance following CDK4/6 inhibition.

Structural modification of the propyl linker of cjoc42 in combination with sulfonate ester and triazole replacements for enhanced gankyrin binding and anti-proliferative activity

Liver cancer is a complex disease that involves various oncoproteins and the inactivation of tumor suppressor proteins (TSPs). Gankyrin is one such oncoprotein, first identified in human hepatocellular carcinoma, that is known to inactivate multiple TSPs, leading to proliferation and metastasis of tumor cells. Despite this, there has been limited development of small molecule gankyrin binders for the treatment of liver cancer. In this study, we are reporting the structure-based design of gankyrin-binding small molecules which inhibit the proliferation of HuH6 and HepG2 cells while also increasing the levels of certain TSPs, such as Rb and p53. Interestingly the first molecule to exhibit inhibition by 3D structure stabilization is seen. These results suggest a possible mechanism for small-molecule inhibition of gankyrin and demonstrate that gankyrin is a viable therapeutic target for the treatment of liver cancer.

Autocrine phosphatase PDP2 inhibits ferroptosis by dephosphorylating ACSL4 in the Luminal A Breast Cancer

Phosphatases can dephosphorylate phosphorylated kinases, leading to their inactivation, and ferroptosis is a type of cell death. Therefore, our aim is to identify phosphatases associated with ferroptosis by analyzing the differentially expressed genes (DEGs) of the Luminal A Breast Cancer (LumABC) cohort from the Cancer Genome Atlas (TCGA). An analysis of 260 phosphatase genes from the GeneCard database revealed that out of the 28 DEGs with high expression, only the expression of pyruvate dehydrogenase phosphatase 2 (PDP2) had a significant correlation with patient survival. In addition, an analysis of DEGs using gene ontology, Kyoto Encyclopedia of Genes and Genomes and gene set enrichment analysis revealed a significant variation in the expression of ferroptosis-related genes. To further investigate this, we analyzed 34 ferroptosis-related genes from the TCGA-LumABC cohort. The expression of long-chain acyl-CoA synthetase 4 (ACSL4) was found to have the highest correlation with the expression of PDP2, and its expression was also inversely proportional to the survival rate of patients. Western blot experiments using the MCF-7 cell line showed that the phosphorylation level of ACSL4 was significantly lower in cells transfected with the HA-PDP2 plasmid, and ferroptosis was correspondingly reduced (p < 0.001), as indicated by data from flow cytometry detection of membrane-permeability cell death stained with 7-aminoactinomycin, lipid peroxidation, and Fe2+. Immunoprecipitation experiments further revealed that the phosphorylation level of ACSL4 was only significantly reduced in cells where PDP2 and ACSL4 co-precipitated. These findings suggest that PDP2 may act as a phosphatase to dephosphorylate and inhibit the activity of ACSL4, which had been phosphorylated and activated in LumABC cells. Further experiments are needed to confirm the molecular mechanism of PDP2 inhibiting ferroptosis.

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.

Gankyrin inhibits ferroptosis through the p53/SLC7A11/GPX4 axis in triple-negative breast cancer cells

Gankyrin is found in high levels in triple-negative breast cancer (TNBC) and has been established to form a complex with the E3 ubiquitin ligase MDM2 and p53, resulting in the degradation of p53 in hepatocarcinoma cells. Therefore, this study sought to determine whether gankyrin could inhibit ferroptosis through this mechanism in TNBC cells. The expression of gankyrin was investigated in relation to the prognosis of TNBC using bioinformatics. Co-immunoprecipitation and GST pull-down assays were then conducted to determine the presence of a gankyrin and MDM2 complex. RT-qPCR and immunoblotting were used to examine molecules related to ferroptosis, such as gankyrin, p53, MDM2, SLC7A11, and GPX4. Additionally, cell death was evaluated using flow cytometry detection of 7-AAD and a lactate dehydrogenase release assay, as well as lipid peroxide C11-BODIPY. Results showed that the expression of gankyrin is significantly higher in TNBC tissues and cell lines, and is associated with a poor prognosis for patients. Subsequent studies revealed that inhibiting gankyrin activity triggered ferroptosis in TNBC cells. Additionally, silencing gankyrin caused an increase in the expression of the p53 protein, without altering its mRNA expression. Co-immunoprecipitation and GST pull-down experiments indicated that gankyrin and MDM2 form a complex. In mouse embryonic fibroblasts lacking both MDM2 and p53, this gankyrin/MDM2 complex was observed to ubiquitinate p53, thus raising the expression of molecules inhibited by ferroptosis, such as SLC7A11 and GPX4. Furthermore, silencing gankyrin in TNBC cells disrupted the formation of the gankyrin/MDM2 complex, hindered the degradation of p53, increased SLC7A11 expression, impeded cysteine uptake, and decreased GPX4 production. Our findings suggest that TNBC cells are able to prevent cell ferroptosis through the gankyrin/p53/SLC7A11/GPX4 signaling pathway, indicating that gankyrin may be a useful biomarker for predicting TNBC prognosis or a potential therapeutic target.

LncRNA NEAT1 suppresses cellular senescence in hepatocellular carcinoma via KIF11-dependent repression of CDKN2A

BACKGROUND

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. Therapeutic options for advanced HCC are limited, which is due to a lack of full understanding of pathogenesis. Cellular senescence is a state of cell cycle arrest, which plays important roles in the pathogenesis of HCC. Mechanisms underlying hepatocellular senescence are not fully understood. LncRNA NEAT1 acts as an oncogene and contributes to the development of HCC. Whether NEAT1 modulates hepatocellular senescence in HCC is unknown.

METHODS

The role of NEAT1 and KIF11 in cellular senescence and tumor growth in HCC was assessed both in vitro and in vivo. RNA pulldown, mass spectrometry, Chromatin immunoprecipitation (ChIP), luciferase reporter assays, RNA FISH and immunofluorescence (IF) staining were used to explore the detailed molecular mechanism of NEAT1 and KIF11 in cellular senescence of HCC.

RESULTS

We found that NEAT1 was upregulated in tumor tissues and hepatoma cells, which negatively correlated with a senescence biomarker CDKN2A encoding p16INK4a and p14ARF proteins. NEAT1 was reduced in senescent hepatoma cells induced by doxorubicin (DOXO) or serum starvation. Furthermore, NEAT1 deficiency caused senescence in cultured hepatoma cells, and protected against the progression of HCC in a mouse model. During senescence, NEAT1 translocated into cytosol and interacted with a motor protein KIF11, resulting in KIF11 protein degradation and subsequent increased expression of CDKN2A in cultured hepatoma cells. Furthermore, KIF11 knockdown caused senescence in cultured hepatoma cells. Genetic deletion of Kif11 in hepatocytes inhibited the development of HCC in a mouse model.

CONCLUSIONS

Conclusively, NEAT1 overexpression reduces senescence and promotes tumor progression in HCC tissues and hepatoma cells, whereas NEAT1 deficiency causes senescence and inhibits tumor progression in HCC. This is associated with KIF11-dependent repression of CDKN2A. These findings lay the foundation to develop potential therapies for HCC by inhibiting NEAT1 and KIF11 or inducing senescence.

A Photoactivated Ru (II) Polypyridine Complex Induced Oncotic Necrosis of A549 Cells by Activating Oxidative Phosphorylation and Inhibiting DNA Synthesis as Revealed by Quantitative Proteomics

The ruthenium polypyridine complex [Ru(dppa)₂(pytp)] (PF₆)₂ (termed as ZQX-1), where dppa = 4,7-diphenyl-1,10-phenanthroline and pytp = 4'-pyrene-2,2':6',2''-terpyridine, has been shown a high and selective cytotoxicity to hypoxic and cisplatin-resistant cancer cells either under irradiation with blue light or upon two-photon excitation. The IC₅₀ values of ZQX-1 towards A549 cancer cells and HEK293 health cells are 0.16 ± 0.09 µM and >100 µM under irradiation at 420 nm, respectively. However, the mechanism of action of ZQX-1 remains unclear. In this work, using the quantitative proteomics method we identified 84 differentially expressed proteins (DEPs) with |fold-change| ≥ 1.2 in A549 cancer cells exposed to ZQX-1 under irradiation at 420 nm. Bioinformatics analysis of the DEPs revealed that photoactivated ZQX-1 generated reactive oxygen species (ROS) to activate oxidative phosphorylation signaling to overproduce ATP; it also released ROS and pyrene derivative to damage DNA and arrest A549 cells at S-phase, which synergistically led to oncotic necrosis and apoptosis of A549 cells to deplete excess ATP, evidenced by the elevated level of PRAP1 and cleaved capase-3. Moreover, the DNA damage inhibited the expression of DNA repair-related proteins, such as RBX1 and GPS1, enhancing photocytotoxicity of ZQX-1, which was reflected in the inhibition of integrin signaling and disruption of ribosome assembly. Importantly, the photoactivated ZQX-1 was shown to activate hypoxia-inducible factor 1A (HIF1A) survival signaling, implying that combining use of ZQX-1 with HIF1A signaling inhibitors may further promote the photocytotoxicity of the prodrug.

Gankyrin-mediated interaction between cancer cells and tumor-associated macrophages facilitates prostate cancer progression and androgen deprivation therapy resistance

Increasing evidence reveals that the interaction between tumor cells and tumor-associated macrophages (TAMs) facilitates the progression of prostate cancer, but the related mechanisms remained unclear. This study determined how gankyrin, a component of the 19S regulatory complex of the 26S proteasome, regulates the progression and androgen deprivation therapy (ADT) resistance of prostate cancer through tumor cell-TAM interactions. In vitro functional experiments and in vivo subcutaneous tumor models were used to explore the biological role and molecular mechanisms of gankyrin in prostate cancer cell-TAM interactions. 234 prostate cancer patients were randomly divided into training and validation cohorts to examine the prognostic value of gankyrin through immunohistochemistry (IHC) and statistical analyses, and high gankyrin expression was correlated with poor prognosis. In addition, gankyrin facilitated the progression and ADT resistance of prostate cancer. Mechanistically, gankyrin recruited and upregulated non-POU-domain-containing octamer-binding protein (NONO) expression, resulting in increased androgen receptor (AR) expression. AR then bound to the high-mobility group box 1 (HMGB1) promoter to trigger HMGB1 transcription, expression, and secretion. Moreover, HMGB1 was found to promote the recruitment and activation of TAMs, which secrete IL-6 to reciprocally promote prostate cancer progression, ADT resistance and gankyrin expression via STAT3, resulting in formation of a gankyrin/NONO/AR/HMGB1/IL-6/STAT3 positive feedback loop. Furthermore, targeting the interaction between tumor cells and TAMs by blocking this loop inhibited ADT resistance in a tumor xenograft model. Taken together, the data show that gankyrin serves as a reliable prognostic indicator and therapeutic target for prostate cancer patients.

EBNA1 Upregulates P53-Inhibiting Genes in Burkitt's Lymphoma Cell Line

Background

Suppression of p53 is an important mechanism in Epstein-Barr virus associate-tumors and described as EBNA1-USP7 which is a key axis in p53 suppression. Thus, in this study, we aimed to evaluate the function of EBNA1 on the expression of p53-inhibiting genes including HDAC-1, MDM2, MDM4, Sirt-3, and PSMD10 and the influence of USP7 inhibition using GNE-6776 on p53 at protein/mRNA level.

Methods

The electroporation method was used to transfect the BL28 cell line with EBNA1. Cells with stable EBNA1 expression were selected by Hygromycin B treatment. The expression of seven genes, including PSMD10, HDAC-1, USP7, MDM2, P53, Sirt-3, and MDM4, was evaluated using a real-time PCR assay. For evaluating the effects of USP7 inhibition, the cells were treated with GNE-6776; after 24 hours and 4 days, the cells were collected and again expression of interest genes was evaluated.

Results

MDM2 (P=0.028), MDM4 (P=0.028), USP7 (P=0.028), and HDAC1 (P=0.015) all showed significantly higher expression in EBNA1-harboring cells compared to control plasmid transfected cells, while p53 mRNA expression was only marginally downregulated in EBNA1 harboring cells (P=0.685). Four-day after treatment, none of the studied genes was significantly changed. Also, in the first 24-hour after treatment, mRNA expression of p53 was downregulated (P=0.685), but after 4 days it was upregulated (P=0.7) insignificantly.

Conclusion

It seems that EBNA1 could strongly upregulate p53-inhibiting genes including HDAC1, MDM2, MDM4, and USP7. Moreover, it appears that the effects of USP7 suppression on p53 at protein/mRNA level depend on the cell nature; however, further research is needed.

Snapshots of urea-induced early structural changes and unfolding of an ankyrin repeat protein at atomic resolution

Protein folding and unfolding is a complex process, underscored by the many proteotoxic diseases associated with misfolded proteins. Mapping pathways from a native structure to an unfolded protein or vice versa, identifying the intermediates, and defining the role of sequence and structure en route remain outstanding problems in the field. It is even more challenging to capture the events at atomistic resolution. X-ray diffraction has so far been used to understand how urea interacts with and unfolds two stable globular proteins. Here, we present the case study on PSMD10Gankyrin , a prototype for a moderately stable, non-globular repeat protein, long and rigid, with its termini located at either end.   We define structural changes in the time dimension using low urea concentrations to arrive at the following conclusions. (a) Unfolding is rapidly initiated at the C-terminus, slowly at the N-terminus, and proceeds inwards from both ends. (b) C-terminus undergoes an α to 310 helix transition, representing the structure of a potential early unfolding intermediate before disorder sets in. (c) Distinct and progressive changes in the electrostatic landscape of PSMD10Gankyrin were observed, indicative of conformational changes in the seemingly inflexible motif involved in protein-protein interaction. We believe this unique study will open up the field for better and bolder queries and increase the choice of model proteins for a better understanding of the challenging problems of protein folding, protein interactions, protein degradation, and diseases associated with misfolding.

Spatial metabolomics on liver cirrhosis to hepatocellular carcinoma progression

Background

Hepatocellular carcinoma (HCC) is one of the deadliest cancers and is mainly developed from chronic liver diseases such as hepatitis-B infection-associated liver cirrhosis (LC). The progression from LC to HCC makes the detection of diagnostic biomarkers to be challenging. Hence, there have been constant efforts to improve on identifying the critical and predictive changes accompanying the disease progression.

Methods

In this study, we looked to using the mass spectrometry mediated spatial metabolomics technique to simultaneous examine hundreds of metabolites in an untargeted fashion. Additionally, metabolic profiles were compared between six subregions within the HCC tissue to collect spatial information.

Results

Through those metabolites, altered metabolic pathways in LC and HCC were identified. Specifically, the amino acid metabolisms and the glycerophospholipid metabolisms experienced the most changes. Many of the altered metabolites and metabolic pathways were able to be connected through the urea cycle.

Conclusions

The identification of the key metabolites and pathways can expand our knowledge on HCC metabolic reprogramming and help us exam potential biomarkers for earlier detection of the malignant disease progression.

Pan-cancer analysis of genomic and transcriptomic data reveals the prognostic relevance of human proteasome genes in different cancer types

Background

The human proteasome gene family (PSM) consists of 49 genes that play a crucial role in cancer proteostasis. However, little is known about the effect of PSM gene expression and genetic alterations on clinical outcome in different cancer forms.

Methods

Here, we performed a comprehensive pan-cancer analysis of genetic alterations in PSM genes and the subsequent prognostic value of PSM expression using data from The Cancer Genome Atlas (TCGA) containing over 10,000 samples representing up to 33 different cancer types. External validation was performed using a breast cancer cohort and KM plotter with four cancer types.

Results

The PSM genetic alteration frequency was high in certain cancer types (e.g. 67%; esophageal adenocarcinoma), with DNA amplification being most common. Compared with normal tissue, most PSM genes were predominantly overexpressed in cancer. Survival analysis also established a relationship with PSM gene expression and adverse clinical outcome, where PSMA1 and PSMD11 expression were linked to more unfavorable prognosis in ≥ 30% of cancer types for both overall survival (OS) and relapse-free interval (PFI). Interestingly, PSMB5 gene expression was associated with OS (36%) and PFI (27%), and OS for PSMD2 (42%), especially when overexpressed.

Conclusion

These findings indicate that several PSM genes may potentially be prognostic biomarkers and novel therapeutic targets for different cancer forms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10079-4.

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.

Small-Molecule Gankyrin Inhibition as a Therapeutic Strategy for Breast and Lung Cancer

Gankyrin is an oncoprotein responsible for the development of numerous cancer types. It regulates the expression levels of multiple tumor suppressor proteins (TSPs) in liver cancer; however, gankyrin's regulation of these TSPs in breast and lung cancers has not been thoroughly investigated. Additionally, no small-molecule gankyrin inhibitor has been developed which demonstrates potent anti-proliferative activity against gankyrin overexpressing breast and lung cancers. Herein, we are reporting the structure-based design of gankyrin-binding small molecules which potently inhibited the proliferation of gankyrin overexpressing A549 and MDA-MB-231 cancer cells, reduced colony formation, and inhibited the growth of 3D spheroids in an in vitro tumor simulation model. Investigations demonstrated that gankyrin inhibition occurs through either stabilization or destabilization of its 3D structure. These studies shed light on the mechanism of small-molecule inhibition of gankyrin and demonstrate that gankyrin is a viable therapeutic target for the treatment of breast and lung cancer.

Novel Nexus with NFκB, β-catenin, and RB1 empowers PSMD10/Gankyrin to counteract TNF-α induced apoptosis establishing its oncogenic role

NFκB is a critical rapid-acting transcription factor that protects cancer cells from programmed cell death induced by stress or therapy. While NFκB works in nexus with non-classical oncoproteins such as STAT3 and AKT under a variety of conditions, it is a major antiapoptotic factor activated by TNF-α of the tumor microenvironment. Therefore, it is surprising that PSMD10, an oncoprotein overexpressed in several cancers and a marker of poor prognosis, is reported to inhibit the NFκB pathway. In this study, we explore the role of PSMD10 in cancer cells exposed to TNF-α. We screen several breast and colon cancer cell lines and select SW480, a colon cancer cell line highly resistant to TNF-α, and demonstrate that PSMD10 knockdown sensitizes these cells to TNF-α induced cell death. One of the mechanisms involves transcriptional regulation of β-catenin and RB1, two key colon cancer cell specific anti-apoptotic factors. Surprisingly, we find that PSMD10 is required for optimal phosphorylation and transcriptional activation of NFκB (RELA). Thus, upon PSMD10 knockdown, there is significant downregulation of anti-apoptotic NFκB target genes TNFAIP3 (A20), BIRC2 (cIAP1), BIRC3 (cIAP2), and XIAP. Our study, for the first time, shows that PSMD10 is required for the activation of the pro-survival arm via NFκB transcriptional activation to prevent cancer cells from succumbing to TNF-induced cell death. In addition by transcriptional regulation of two major antiapoptotic players RB1 and β-catenin, PSMD10 proves to be a coveted oncoprotein with a key role in tumorigenesis.

Comparative Metabolomics and Proteomics Reveal Vibrio parahaemolyticus Targets Hypoxia-Related Signaling Pathways of Takifugu obscurus

Coronavirus disease 2019 (COVID-19) raises the issue of how hypoxia destroys normal physiological function and host immunity against pathogens. However, there are few or no comprehensive omics studies on this effect. From an evolutionary perspective, animals living in complex and changeable marine environments might develop signaling pathways to address bacterial threats under hypoxia. In this study, the ancient genomic model animal Takifugu obscurus and widespread Vibrio parahaemolyticus were utilized to study the effect. T. obscurus was challenged by V. parahaemolyticus or (and) exposed to hypoxia. The effects of hypoxia and infection were identified, and a theoretical model of the host critical signaling pathway in response to hypoxia and infection was defined by methods of comparative metabolomics and proteomics on the entire liver. The changing trends of some differential metabolites and proteins under hypoxia, infection or double stressors were consistent. The model includes transforming growth factor-β1 (TGF-β1), hypoxia-inducible factor-1α (HIF-1α), and epidermal growth factor (EGF) signaling pathways, and the consistent changing trends indicated that the host liver tended toward cell proliferation. Hypoxia and infection caused tissue damage and fibrosis in the portal area of the liver, which may be related to TGF-β1 signal transduction. We propose that LRG (leucine-rich alpha-2-glycoprotein) is widely involved in the transition of the TGF-β1/Smad signaling pathway in response to hypoxia and pathogenic infection in vertebrates as a conserved molecule.

Gankyrin activates the hedgehog signalling to drive metastasis in osteosarcoma

Gankyrin is a regulatory subunit of the 26-kD proteasome complex and promotes the occurrence and progression of many malignancies. However, the role of gankyrin in osteosarcoma (OS) metastasis remains unclear. Hedgehog signalling has been shown to regulate stem cell homeostasis and cancer metastasis, but the mechanisms that activate this pathway in OS are still poorly understood. Here, a series of in vitro and in vivo assays were carried out to explore the function and mechanism of gankyrin regulating Hedgehog signalling in OS. We demonstrated that gankyrin promotes migration, invasion and regulates the expression of some stemness factors by up-regulating Gli1 in OS. Importantly, our data showed an interaction between gankyrin and Gli1. Moreover, gankyrin suppresses the ubiquitin-mediated degradation of Gli1 protein in OS. Gankyrin also significantly promotes the lung metastasis of OS in vivo. Our findings suggest that gankyrin drives metastasis and regulates the expression of some stemness factors in osteosarcoma by activating Hedgehog signalling, indicating that drug screening for compounds targeting gankyrin may contribute to the development of novel and effective therapies for OS.

Ubiquitin-proteasome system and the role of its inhibitors in cancer therapy

Despite all the other cells that have the potential to prevent cancer development and metastasis through tumour suppressor proteins, cancer cells can upregulate the ubiquitin–proteasome system (UPS) by which they can degrade tumour suppressor proteins and avoid apoptosis. This system plays an extensive role in cell regulation organized in two steps. Each step has an important role in controlling cancer. This demonstrates the importance of understanding UPS inhibitors and improving these inhibitors to foster a new hope in cancer therapy. UPS inhibitors, as less invasive chemotherapy drugs, are increasingly used to alleviate symptoms of various cancers in malignant states. Despite their success in reducing the development of cancer with the lowest side effects, thus far, an appropriate inhibitor that can effectively inactivate this system with the least drug resistance has not yet been fully investigated. A fundamental understanding of the system is necessary to fully elucidate its role in causing/controlling cancer. In this review, we first comprehensively investigate this system, and then each step containing ubiquitination and protein degradation as well as their inhibitors are discussed. Ultimately, its advantages and disadvantages and some perspectives for improving the efficiency of these inhibitors are discussed.

Identification of a covalent binder to the oncoprotein gankyrin using a NIR-Based OBOC screening method

Despite huge advancements in the process of synthesizing small molecules as part of one-bead-one-compound (OBOC) libraries, progress lags in the ability to screen these libraries against proteins of interest. Recently, we developed a method to screen OBOC libraries in which a target protein is labeled with a near-infrared (NIR) range fluorophore. The labeled protein incubates with beads of a library in a 96-well plate, then the plate is imaged for fluorescence. Fluorescence intensities produced by the labeled protein binding the bead can be quantitated and provide a basis to rank hits. Here, we present an application of this technique by screening the oncoprotein gankyrin against a 343-member peptoid library. The library was composed of four positions occupied by one of seven amines. In the third position, an amine that facilitates covalent binding via a sulfonyl fluoride moiety was incorporated. After screening for gankyrin binders twice, ten structures showed overlap in the types of amines present at each position. These initial hits were validated with an in-gel fluorescence assay in which the labeled ligands covalently interacted with purified gankyrin. Excitingly, one peptoid was validated from this analysis. This hit was also shown to bind gankyrin in the presence of HEK 293T lysate. Results from this study demonstrate successful use of our screening method to quickly identify quality binders to a target protein of interest.

Cancer and Tumour Suppressor p53 Encounters at the Juncture of Sex Disparity

There are many differences in cancer manifestation between men and women. New understanding of the origin of these point to fundamental distinctions in the genetic code and its demise. Tumour suppressor protein p53 is the chief operating officer of cancer defence and critically acts to safeguard against sustained DNA damaged. P53 cannot be ignored in cancer sex disparity. In this review we discuss the greater prevalence and associated death rates for non-reproductive cancers in males. The major tumour suppressor protein p53, encoded in the TP53 gene is our chosen context. It is fitting to ask why somatic TP53 mutation incidence is estimated to be disproportionately higher among males in the population for these types of cancers compared with females? We scrutinised the literature for evidence of predisposing genetic and epigenetic alterations that may explain this sex bias. Our second approach was to explore whether redox activity, either externally imposed or inherent to males and females, may define distinct risks that could contribute to the clear cancer sex disparities.

Structural Insights into Ankyrin Repeat-Containing Proteins and Their Influence in Ubiquitylation

Ankyrin repeat (AR) domains are considered the most abundant repeat motif found in eukaryotic proteins. AR domains are predominantly known to mediate specific protein-protein interactions (PPIs) without necessarily recognizing specific primary sequences, nor requiring strict conformity within its own primary sequence. This promiscuity allows for one AR domain to recognize and bind to a variety of intracellular substrates, suggesting that AR-containing proteins may be involved in a wide array of functions. Many AR-containing proteins serve a critical role in biological processes including the ubiquitylation signaling pathway (USP). There is also strong evidence that AR-containing protein malfunction are associated with several neurological diseases and disorders. In this review, the structure and mechanism of key AR-containing proteins are discussed to suggest and/or identify how each protein utilizes their AR domains to support ubiquitylation and the cascading pathways that follow upon substrate modification.

Quantitative expression of Ikaros, IRF4, and PSMD10 proteins predicts survival in VRD-treated patients with multiple myeloma

The search for biomarkers based on the mechanism of drug action has not been thoroughly addressed in the therapeutic approaches to multiple myeloma (MM), mainly because of the difficulty in analyzing proteins obtained from purified plasma cells. Here, we investigated the prognostic impact of the expression of 12 proteins involved in the mechanism of action of bortezomib, lenalidomide, and dexamethasone (VRD), quantified by capillary nanoimmunoassay, in CD138-purified samples from 174 patients with newly diagnosed MM treated according to the PETHEMA/GEM2012 study. A high level of expression of 3 out of 5 proteasome components tested (PSMD1, PSMD4, and PSMD10) negatively influenced survival. The 5 analyzed proteins involved in lenalidomide's mode of action were associated with time to progression (TTP); low levels of cereblon and IRF4 protein and high levels of Ikaros, AGO2, and Aiolos were significantly associated with shorter TTP. Although the glucocorticoid receptor (GCR) level by itself had no significant impact on MM prognosis, a high XPO1 (exportin 1)/GCR ratio was associated with shorter TTP and progression-free survival (PFS). The multivariate Cox model identified high levels of PSMD10 (hazard ratio [HR] TTP, 3.49; P = .036; HR PFS, 5.33; P = .004) and Ikaros (HR TTP, 3.01, P = .014; HR PFS, 2.57; P = .028), and low levels of IRF4 protein expression (HR TTP, 0.33; P = .004; HR PFS, 0.35; P = .004) along with high-risk cytogenetics (HR TTP, 3.13; P < .001; HR PFS, 2.69; P = .002), as independently associated with shorter TTP and PFS. These results highlight the value of assessing proteins related to the mechanism of action of drugs used in MM for predicting treatment outcome.

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.

LINC00665 Promotes the Progression of Multiple Myeloma by Adsorbing miR-214-3p and Positively Regulating the Expression of PSMD10 and ASF1B

Background

Although assertion that long non-coding RNA (lncRNA) exerts crucial functions in the progression of multiple myeloma (MM) is well documented, few studies investigate function and underlying mechanism of long intergenic non-protein coding RNA 665 (LINC00665) in MM.

Patients and Methods

A total of 25 MM patient samples and 15 healthy volunteer samples were collected, and quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect the expressions of LINC00665. PSMD10 and ASF1B expressions were determined by qRT-PCR and Western blot assays. U266 cell and H929 cell were used in functional experiments. Besides, CCK-8 assay and flow cytometry analysis were utilized to determine cell proliferation and apoptosis. Bioinformatics analysis and dual-luciferase reporter assays were used to predict and verify the targeting relationships between LINC00665 and miR-214-3p, PSMD10 and miR-214-3p, as well as ASF1B and miR-214-3p. Moreover, the regulatory function of LINC00665 on the expression of PSMD10 and ASF1B was detected by Western blot.

Results

The expression of LINC00665 was up-regulated in MM samples and cell lines. In vitro functional assays indicated that LINC00665 enhanced MM cell proliferation and inhibited its apoptosis. PSMD10 and ASF1B were identified as target genes of miR-214-3p. Additionally, LINC00665 negatively regulated miR-214-3p expression through sponging miR-214-3p and positively regulated PSMD10 and ASF1B.

Conclusion

LINC00665 can promote the expression of PSMD10 and ASF1B by inhibiting the expression of miR-214-3p, thus facilitating the proliferation and inhibiting apoptosis of MM cells.

Optimizing the aryl-triazole of cjoc42 for enhanced gankyrin binding and anti-cancer activity

Gankyrin is an oncoprotein overexpressed in numerous cancer types and appears to play a key role in regulating cell proliferation, cell growth, and cell migration. These roles are largely due to gankyrin's protein-protein interaction with the 26S proteasome. We previously published a study exploring the aryl sulfonate ester of cjoc42 in an effort to enhance gankyrin binding and inhibit cancer cell proliferation. In order to further improve the gankyrin binding ability of the cjoc42 scaffold, an extensive SAR for the aryl-triazole moiety of cjoc42 was developed. Our cjoc42 derivatives exhibited enhanced gankyrin binding, as well as enhanced antiproliferative activity against Hep3B, HepG2, A549, and MDA-MB-231 cancer cell lines.

p28GANK overexpression is associated with chemotherapy resistance and poor prognosis in ovarian cancer

The non-ATPase regulatory subunit 10 of the human 26S proteasome (p28GANK) has been implicated in the tumorigenesis and progression of several types of malignant tumor. The aim of the present study was to detect the expression of p28GANK in ovarian cancer (OC) and investigate its association with the clinicopathological features and prognosis of OC. The expression levels of p28GANK were determined in 114 OC tissue samples and 30 normal ovarian tissue samples using immunohistochemistry. An association was observed between p28GANK overexpression and certain clinicopathological factors, including advanced International Federation of Gynecology and Obstetrics stage (P=0.042), residual tumor size (P=0.005) and response to chemotherapy (P<0.001). Furthermore, patients with high expression of p28GANK demonstrated worse overall survival (OS) and disease-free survival (DFS) rates compared with patients with low expression of p28GANK (both P<0.001). Multivariate Cox regression analysis revealed that overexpression of p28GANK was an independent prognostic factor of OS and DFS in patients with OC (P=0.013 and P=0.001, respectively). In summary, the current results indicate that p28GANK may be a predictive marker and a therapeutic target for OC.

Ubiquitin-Regulated Cell Proliferation and Cancer

Ubiquitin ligases (E3) play a crucial role in the regulation of different cellular processes such as proliferation and differentiation via recognition, interaction, and ubiquitination of key cellular proteins in a spatial and temporal regulated manner. The type of ubiquitin chain formed determines the fate of the substrates. The ubiquitinated substrates can be degraded by the proteasome, display altered subcellular localization, or can suffer modifications on their interaction with functional protein complexes. Deregulation of E3 activities is frequently found in various human pathologies, including cancer. The illegitimated or accelerated degradation of oncosuppressive proteins or, inversely, the abnormally high accumulation of oncoproteins, contributes to cell proliferation and transformation. Anomalies in protein abundance may be related to mutations that alter the direct or indirect recognition of proteins by the E3 enzymes or alterations in the level of expression or activity of ubiquitin ligases. Through a few examples, we illustrate here the complexity and diversity of the molecular mechanisms related to protein ubiquitination involved in cell cycle regulation. We will discuss the role of ubiquitin-dependent degradation mediated by the proteasome, the role of non-proteolytic ubiquitination during cell cycle progression, and the consequences of this deregulation on cellular transformation. Finally, we will highlight the novel opportunities that arise from these studies for therapeutic intervention.

Increased Expression of Gankyrin and Stemness Factor Oct-4 are Associated with Unfavorable Clinical Outcomes and Poor Benefit of Tamoxifen in Breast Carcinoma Patients

Tamoxifen is the most important treatment component in estrogen receptor positive (ER+) breast carcinoma patients. Tamoxifen resistance incidence presents an important obstacle in clinical treatment. Mechanisms underlying tamoxifen refractory are not completely understood. Although elevated expression of Gankyrin (P28GANK) and stem cell markers Nanog, Oct-4 and Sox-2 have been reported in breast carcinoma, their role in tamoxifen resistance progression has not been explored. In the present study, P28GANK and stem cell markers Nanog, Oct-4 and Sox-2 expression were evaluated using quantitative RT-PCR and immunohistochemical technology in 72 breast carcinoma patients who received tamoxifen as adjuvant anti-hormone treatment. Expression data were correlated with the clinical outcome and survival of patients. Data analysis showed that P28GANK, Oct-4 and Sox-2 transcripts were significantly overexpressed in tamoxifen resistance patients. Immunohistochemical staining indicated that protein expression of P28GANK and Oct-4 were also significantly higher in tamoxifen resistance patients. We have shown a positive correlation between mRNA and protein expression of P28GANK, Oct-4 and Sox-2. Multivariate logistic regression analysis indicated that P28GANK (P = 0.002) and Oct-4 (P = 0.013) overexpression could be negative independent factors of disease outcome. Additionally, in the whole study group, multivariate Cox regression analysis revealed that high expression of P28GANK and Oct-4 remained significant and unfavorable predictive factors for patients' survival. These findings suggest that Gankyrin and Oct-4 overexpression could promote tamoxifen refractory in breast cancer patients. More studies are warranted to clarify the predictive role of these potential biomarkers for patients who don't benefit from tamoxifen treatment and their possible application as prognostic markers in ER⁺ tamoxifen-treated breast carcinoma patients.

Identification of cancer sex-disparity in the functional integrity of p53 and its X chromosome network

The disproportionately high prevalence of male cancer is poorly understood. We tested for sex-disparity in the functional integrity of the major tumor suppressor p53 in sporadic cancers. Our bioinformatics analyses expose three novel levels of p53 impact on sex-disparity in 12 non-reproductive cancer types. First, TP53 mutation is more frequent in these cancers among US males than females, with poorest survival correlating with its mutation. Second, numerous X-linked genes are associated with p53, including vital genomic regulators. Males are at unique risk from alterations of their single copies of these genes. High expression of X-linked negative regulators of p53 in wild-type TP53 cancers corresponds with reduced survival. Third, females exhibit an exceptional incidence of non-expressed mutations among p53-associated X-linked genes. Our data indicate that poor survival in males is contributed by high frequencies of TP53 mutations and an inability to shield against deregulated X-linked genes that engage in p53 networks.

The oncogene Gankyrin is expressed in testicular cancer and contributes to cisplatin sensitivity in embryonal carcinoma cells

BACKGROUND

Testicular germ cell cancer (TGCC) develops from pre-malignant germ neoplasia in situ (GCNIS) cells. GCNIS originates from fetal gonocytes (POU5F1+/MAGE-A4-), which fail to differentiate to pre-spermatogonia (POU5F1-/MAGE-A4+) and undergo malignant transformation. Gankyrin is an oncogene which has been shown to prevent POU5F1 degradation and specifically interact with MAGE-A4 in hepatocellular carcinoma (HCC) cells. We aimed to investigate the role of Gankyrin in progression from gonocyte to pre-invasive GCNIS and subsequent invasive TGCC.

METHODS

We determined Gankyrin expression in human fetal testicular tissue (gestational weeks 9-20; n = 38), human adult testicular tissue with active spermatogenesis (n = 9), human testicular tissue with germ cell maturation delay (n = 4), testicular tissue from patients with pre-invasive GCNIS (n = 6), and invasive TGCC including seminoma (n = 6) and teratoma (n = 7). Functional analysis was performed in-vitro by siRNA knock-down of Gankyrin in the NTera2 cells (derived from embryonal carcinoma).

RESULTS

Germ cell expression of Gankyrin was restricted to a sub-population of prespermatogonia in human fetal testes. Nuclear Gankyrin was also expressed in GCNIS cells of childhood and adult pre-invasive TGCC patients, and in GCNIS from seminoma and non-seminoma patients. Cytoplasmic expression was observed in seminoma tumour cells and NTera2 cells. Gankyrin knock-down in NTera2 cells resulted in an increase in apoptosis mediated via the TP53 pathway, whilst POU5F1 expression was unaffected. Furthermore, Gankyrin knock-down in NTera2 cells increased cisplatin sensitivity with an increase in cell death (13%, p < 0.05) following Gankyrin knock-down, when compared to cisplatin treatment alone, likely via BAX and FAS. Our results demonstrate that Gankyrin expression changes in germ cells during normal transition from gonocyte to prespermatogonia. In addition, changes in Gankyrin localisation are associated with progression of pre-invasive GCNIS to invasive TGCC. Furthermore, we found that Gankyrin is involved in the regulation of NTera2 cell survival and that a reduction in Gankyrin expression can modulate cisplatin sensitivity.

CONCLUSIONS

These results suggest that manipulation of Gankyrin expression may reduce the cisplatin dose required for the treatment of TGCC, with benefits in reducing dose-dependent side effects of chemotherapy. Further studies are required in order to assess the effects of modulating Gankyrin on GCNIS/TGCC using in vivo models.

Identification of key biomarkers associated with development and prognosis in patients with ovarian carcinoma: evidence from bioinformatic analysis

BACKGROUND

Ovarian cancer (OC) is the deadliest cause in the gynecological malignancies. Most OC patients are diagnosed in advanced stages with less than 40% of women cured. However, the possible mechanism underlying tumorigenesis and candidate biomarkers remain to be further elucidated.

RESULTS

Gene expression profiles of GSE18520, GSE54388, and GSE27651 were available from Gene Expression Omnibus (GEO) database with a total of 91 OC samples and 22 normal ovarian (OV) tissues. Three hundred forty-nine differentially expressed genes (DEGs) were screened between OC tissues and OV tissues via GEO2R and online Venn software, followed by KEGG pathway and gene ontology (GO) enrichment analysis. The enriched functions and pathways of these DEGs contain male gonad development, cellular response to transforming growth factor beta stimulus, positive regulation of transcription from RNA polymerase II promoter, calcium independent cell-cell adhesion via plasma membrane cell adhesion molecules, extracellular matrix organization, pathways in cancer, cell cycle, cell adhesion molecules, PI3K-AKT signaling pathway, and progesterone mediated oocyte maturation. The protein-protein network (PPI) was established and module analysis was carried out using STRING and Cytoscape. Next, with PPI network analyzed by four topological methods in Cytohubba plugin of Cytoscape, 6 overlapping genes (DTL, DLGAP5, KIF15, NUSAP1, RRM2, and TOP2A) were eventually selected. GEPIA and Oncomine were implemented for validating the gene expression and all the six hub genes were highly expressed in OC specimens compared to normal OV tissues. Furthermore, 5 of 6 genes except for DTL were associated with worse prognosis using Kaplan Meier-plotter online tool and 3 of 6 genes were significantly related to clinical stages, including RRM2, DTL, and KIF15. Additionally, cBioPortal showed that TOP2A and RRM2 were the targets of cancer drugs in patients with OC, indicating the other four genes may also be potential drug targets.

CONCLUSION

Six hub genes (DTL, DLGAP5, KIF15, NUSAP1, RRM2, and TOP2A) present promising predictive value for the development and prognosis of OC and may be used as candidate targets for diagnosis and treatment of OC.

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.

Regulation of proteasome assembly and activity in health and disease

The proteasome degrades most cellular proteins in a controlled and tightly regulated manner and thereby controls many processes, including cell cycle, transcription, signalling, trafficking and protein quality control. Proteasomal degradation is vital in all cells and organisms, and dysfunction or failure of proteasomal degradation is associated with diverse human diseases, including cancer and neurodegeneration. Target selection is an important and well-established way to control protein degradation. In addition, mounting evidence indicates that cells adjust proteasome-mediated degradation to their needs by regulating proteasome abundance through the coordinated expression of proteasome subunits and assembly chaperones. Central to the regulation of proteasome assembly is TOR complex 1 (TORC1), which is the master regulator of cell growth and stress. This Review discusses how proteasome assembly and the regulation of proteasomal degradation are integrated with cellular physiology, including the interplay between the proteasome and autophagy pathways. Understanding these mechanisms has potential implications for disease therapy, as the misregulation of proteasome function contributes to human diseases such as cancer and neurodegeneration.

Prognostic value of DLGAP5 in colorectal cancer

PURPOSE

DLG7 (disc large homolog 7) is a microtubule-associated protein encoded by DLGAP5 (DLG associated protein 5) gene and has an important role during spindle assembly. Spindle assembly deregulation is a well-known cause of genomic instability. The aim of this study was to investigate the influence of DLGAP5 expression on survival and to evaluate its potential use as a biomarker in colorectal cancer (CRC).

METHODS

DLGAP5 expression was measured in the primary tumor and corresponding normal mucosa samples from 109 patients with CRC and correlated to clinical and pathological data. The results were validated in a second, publically available patient cohort. Molecular effects of DLG7/DLGAP5 in CRC were analyzed via functional assays in knockdown cell lines.

RESULTS

DLGAP5 downregulation led to a significant reduction of the invasion and migration potential in CRC. In addition, DLGAP5 expression correlates with nodal status and advanced UICC stage (III-IV).Subgroup analyses revealed a correlation between DLGAP5 overexpression and poor survival in patients with non-metastatic disease (M0). Furthermore, overexpression of DLGAP5 is associated with worse overall survival in distinct molecular CRC subtypes.

CONCLUSIONS

The results of this study suggest the importance of DLGAP5 in defining a more aggressive CRC phenotype. DLG7/DLGAP5 represents a potential biomarker for CRC in molecular subgroups of CRC.

Plumbagin inhibits proliferation and induces apoptosis of hepatocellular carcinoma by downregulating the expression of SIVA

Purpose: Plumbagin is thought to be a bioactive phytochemical drug and exerts an antitumor effect on various cancers. However, few studies focus on the antitumor activity of plumbagin on liver cancer. This study first investigated the antitumor activity of plumbagin on liver cancer and further investigated the molecular mechanism of its antitumor activity against hepatocellular carcinoma, both in vitro and in vivo.

Methods: The antiproliferative activity of plumbagin was evaluated through CCK-8, EdU, and colony forming test. The cell cycle and apoptosis were then analyzed by flow cytometer. Western blot was used to detect the expression of apoptosis related protein, SIVA, and mTOR pathway. RNA-seq was performed to determine the gene expression profiles and overexpressed or knocked down SIVA to validate its role in plumbagin’s antitumor activity. Regarding animal experiment, a xenograft model in BALB/c nude mice was built using LM3-Luci cells. Then bioluminescence imaging and further immunohistochemistry were performed to study the antitumor activity and the expression of SIVA and mTOR in the plumbagin-treated group.

Results: Plumbagin can inhibit proliferation and induce apoptosis of liver cancer cells in vitro. Further experiment demonstrated that plumbagin could inhibit the expression of SIVA and subsequently downregulate the mTOR signaling pathway, and upregulating the expression of SIVA will alleviate the antitumor activity of plumbagin on liver cancer, which confirmed the important role of the SIVA/mTOR signaling pathway in the antitumor activity of plumbagin. In vivo bioluminescence imaging showed a decreased signal in the plumbagin-treated group, and further immunohistochemistry demonstrated that plumbagin could inhibit the SIVA/mTOR signaling pathway in tumor tissues.

Conclusion: Our promising results showed that plumbagin could inhibit proliferation and induce apoptosis of hepatic cancer through inhibiting the SIVA/mTOR signaling pathway for the first time, which indicated that plumbagin might be a good candidate against liver cancer.

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 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.

Hepatocellular Carcinoma: Causes, Mechanism of Progression and Biomarkers

Hepatocellular Carcinoma (HCC) is one of the most common malignant tumours in the world. It is a heterogeneous group of a tumour that vary in risk factor and genetic and epigenetic alteration event. Mortality due to HCC in last fifteen years has increased. Multiple factors including viruses, chemicals, and inborn and acquired metabolic diseases are responsible for its development. HCC is closely associated with hepatitis B virus, and at least in some regions of the world with hepatitis C virus. Liver injury caused by viral factor affects many cellular processes such as cell signalling, apoptosis, transcription, DNA repair which in turn induce important effects on cell survival, growth, transformation and maintenance. Molecular mechanisms of hepatocellular carcinogenesis may vary depending on different factors and this is probably why a large set of mechanisms have been associated with these tumours. Various biomarkers including α-fetoprotein, des-γ-carboxyprothrombin, glypican-3, golgi protein-73, squamous cell carcinoma antigen, circulating miRNAs and altered DNA methylation pattern have shown diagnostic significance. This review article covers up key molecular pathway alterations, biomarkers for diagnosis of HCC, anti-HCC drugs and relevance of key molecule/pathway/receptor as a drug target.

The oncoprotein gankyrin promotes the development of colitis-associated cancer through activation of STAT3

Although long-standing colonic inflammation due to refractory inflammatory bowel disease (IBD) promotes the development of colitis-associated cancer (CAC), the molecular mechanisms accounting for the development of CAC remains largely unknown. In this study, we investigated the role of gankyrin in the development of CAC since gankyrin is overexpressed in sporadic colorectal cancers. We analyzed gene expression of colon tissues obtained from 344 patients with IBD and CAC and found that expression of gankyrin was much higher in colonic mucosa of patients with refractory IBD than in those with IBD in remission. Expression of gankyrin was upregulated in inflammatory cells as well as tumor cells in colonic mucosa of patients with CAC. Over-expressing studies utilizing tagged ganlyrin-cDNA identified physical interaction between ganlyrin and Src homology 2-containing protein tyrosine phosphatase-1 (SHP-1). Importantly, the interaction between ganlyrin and SHP-1 leads to inhibition of STAT3 activation and to enhancement of TNF-α and IL-17 in inflammatory cells. To further address the role of gankyrin in the development of CAC, we created mice with intestinal epithelial cell-specific gankyrin ablation (Vil-Cre;Gankyrin^f/f) and deletion of gankyrin in myeloid and epithelial cells (Mx1-Cre;Gankyrin^f/f). Gankyrin deficiency in myeloid cells, but not in epithelial cells, reduced the activity of mitogen activated protein kinase and the expression of stem cell markers, leading to attenuated tumorigenic potential. These findings provide important insights into the pathogenesis of CAC and suggest that gankyrin is a promising target for developing therapeutic and preventive strategies against CAC.

MDM2-p53 Interactions in Human Hepatocellular Carcinoma: What Is the Role of Nutlins and New Therapeutic Options?

Human hepatocellular carcinoma (HCC) is the fifth most common cancer and is associated with poor prognosis worldwide. The molecular mechanisms underlying the pathogenesis of HCC have been an area of continuing interest, and recent studies using next generation sequencing (NGS) have revealed much regarding previously unsettled issues. Molecular studies using HCC samples have been mainly targeted with the aim to identify the fundamental mechanisms contributing to HCC and identify more effective treatments. In response to cellular stresses (e.g., DNA damage or oncogenes), activated p53 elicits appropriate responses that aim at DNA repair, genetic stability, cell cycle arrest, and the deletion of DNA-damaged cells. On the other hand, the murine double minute 2 (MDM2) oncogene protein is an important cellular antagonist of p53. MDM2 negatively regulates p53 activity through the induction of p53 protein degradation. However, current research has shown that the mechanisms underlying MDM2-p53 interactions are more complex than previously thought. Microarray data have added new insight into the transcription changes in HCC. Recently, Nutlin-3 has shown potency against p53-MDM2 binding and the enhancement of p53 stabilization as well as an increment of p53 cellular accumulation with potential therapeutic effects. This review outlines the molecular mechanisms involved in the p53-MDM2 pathways, the biological factors influencing these pathways, and their roles in the pathogenesis of HCC. It also discusses the action of Nutlin-3 treatment in inducing growth arrest in HCC and elaborates on future directions in research in this area. More research on the biology of p53-MDM2 interactions may offer a better understanding of these mechanisms and discover new biomarkers, sensitive prognostic indicators as well as new therapeutic interventions in HCC.

Arctigenin Inhibits Liver Cancer Tumorigenesis by Inhibiting Gankyrin Expression via C/EBPα and PPARα

Burdock (Arctium lappa) is a popular vegetable in China and Japan that is consumed for its general health benefits. The principal active component of burdock is arctigenin, which shows a range of bioactivities in vivo and in vitro. Here, we investigated the potential anti-tumor effects of arctigenin using two human hepatocellular carcinoma (HCC) cell lines, HepG2 and Hep3B, and sought to elucidate its potential mechanisms of action. Our results showed that arctigenin treatment inhibited cell growth in both HepG2 and Hep3B cell lines (IC₅₀ of 4.74 nM for HepG2 cells, and of 59.27 nM for Hep3B cells). In addition, migration, invasion, and colony formation by HepG2 cells were significantly inhibited by arctigenin. By contrast, treatment of Hep3B cells with arctigenin did not alter these parameters. Arctigenin also significantly reduced the levels of gankyrin mRNA and protein in HepG2 cells, but not in Hep3B cells. A luciferase assay indicated that arctigenin targeted the -450 to -400 region of the gankyrin promoter. This region is also the potential binding site for both C/EBPα and PPARα, as predicted and confirmed by an online software analysis and ChIP assay. Additionally, a co-immunoprecipitation (Co-IP) assay showed that binding between C/EBPα and PPARα was increased in the presence of arctigenin. However, arctigenin did not increase the expression of C/EBPα or PPARα protein. A binding screening assay and liquid chromatography-mass spectrometry (LC-MS) were performed to identify the mechanisms by which arctigenin regulates gankyrin expression. The results suggested that arctigenin could directly increase C/EBPα binding to the gankyrin promoter (-432 to -422 region), but did not affect PPARα binding. Expression of gankyrin, C/EBPα, and PPARα were analyzed in tumor tissues of patients using real-time PCR. Both C/EBPα and PPARα showed negative correlations with gankyrin. In tumor-bearing mice, arctigenin had a significant inhibitory effect on HCC growth. In conclusion, our results suggested that arctigenin could inhibit liver cancer growth by directly recruiting C/EBPα to the gankyrin promoter. PPARα subsequently bound to C/EBPα, and both had a negative regulatory effect on gankyrin expression. This study has identified a new mechanism of action of arctigenin against liver cancer growth.

Gankyrin sustains PI3K/GSK-3β/β-catenin signal activation and promotes colorectal cancer aggressiveness and progression

High levels of angiogenesis, metastasis and chemoresistance are major clinical features of colorectal cancer (CRC), a lethal disease with a high incidence worldwide. Aberrant activation of Wnt/β-catenin pathway contributes to CRC progression. However, little is known about regulatory mechanisms of the β-catenin activity in cancer progression. Here we report that Gankyrin was markedly upregulated in primary tumor tissues from CRC patients and was associated with poor survival. Moreover, we demonstrated that overexpressing Gankyrin promoted, while knockdown of Gankyrin impaired, the aggressive phenotype of proliferation, angiogenesis, chemoresistance and metastasis of CRC cells both in vitro and in vivo. Importantly, we found a unique molecular mechanism of Gankyrin in CRC cells signaling transduction, that regulated the cross-talk between PI3K/Akt and Wnt/β-catenin signaling pathways, sustaining PI3K/GSK-3β/β-catenin signal activation in CRC. Therefore, these findings not only reveal a mechanism that promotes aggressiveness and progression in CRC, but also provide insight into novel molecular targets for antitumor therapy in CRCs.

The transcription levels and prognostic values of seven proteasome alpha subunits in human cancers

Proteasome alpha subunits (PSMAs) have been shown to participate in the malignant progression of human cancers. However, the expression patterns and prognostic values of individual PSMAs remain elusive in most cancers. In the present study, we investigated the mRNA expression levels of seven PSMAs in different kinds of cancers using Oncomine and The Cancer Genome Atlas (TCGA) databases. The prognostic significance of PSMAs was also determined by Kaplan-Meier Plotter and PrognScan databases. Combined with Oncomine and TCGA, the mRNA expression levels of PSMA1-7 were significantly upregulated in breast, lung, gastric, bladder and head and neck cancer compared with normal tissues. Moreover, only PSMA6 and PSMA5 were not overexpressed in colorectal and kidney cancer, respectively. In survival analyses based on Kaplan-Meier Plotter, PSMA1-7 showed significant prognostic values in breast, lung and gastric cancer. Furthermore, potential correlations between PSMAs and survival outcomes were also observed in ovarian cancer, colorectal cancer and melanoma by Kaplan-Meier Plotter and PrognScan. These data indicated that PSMAs might serve as novel biomarkers and potential therapeutic targets for multiple human cancers. However, further studies are needed to explore the detailed biological functions and molecular mechanisms involved in tumor progression.

Unexpected Lower Expression of Oncoprotein Gankyrin in Drug Resistant ABCG2 Overexpressing Breast Cancer Cell Lines

Background: Development of a multidrug resistance (MDR) phenotype to chemotherapy remains a major barrier in the treatment of cancer. Gankyrin (p28, p28GANK or PSMD10) is an oncoprotein overexpressed in different carcinoma cell lines. The aim of this study was to compare Gankyrin expression level in MDR cells (MCF-7/ADR and MCF-7/ MX) and non-MDR counterparts (MCF-7). Methods: Gankyrin, MDR1 (also known as ABCB1; the ATP-binding cassette sub-family B member 1) and ABCG2 (also known as BCRP; the human breast cancer resistance protein) mRNA levels were analyzed by real-time RT-PCR. Western blot analysis was used to detect the protein expression levels of Gankyrin. Results: The PCR results showed that the expression of Gankyrin was significantly lower in the ABCG2 overexpressing cell line MCF-7/MX than in non-resistanct MCF-7 cells. In contrast, there were no significant differences in mRNA expression of Gankyrin in the MDR1 overexpressing cell line MCF-7/ADR in comparison with MCF-7 cells. Similarly, Western blot analysis confirmed lower expression of Gankyrin protein in the MCF-7/MX cell line (26% compared to controls) but not in MCF-7/ADR cells. Conclusion: These findings showed that there may be a relation between down-regulation of Gankyrin and overexpression of ABCG2 but without any clear relationship with MDR1 expression in breast cancer cell lines.

Vaccinia Virus Encodes a Novel Inhibitor of Apoptosis That Associates with the Apoptosome

Apoptosis is an important antiviral host defense mechanism. Here we report the identification of a novel apoptosis inhibitor encoded by the vaccinia virus (VACV) M1L gene. M1L is absent in the attenuated modified vaccinia virus Ankara (MVA) strain of VACV, a strain that stimulates apoptosis in several types of immune cells. M1 expression increased the viability of MVA-infected THP-1 and Jurkat cells and reduced several biochemical hallmarks of apoptosis, such as PARP-1 and procaspase-3 cleavage. Furthermore, ectopic M1L expression decreased staurosporine-induced (intrinsic) apoptosis in HeLa cells. We then identified the molecular basis for M1 inhibitory function. M1 allowed mitochondrial depolarization but blocked procaspase-9 processing, suggesting that M1 targeted the apoptosome. In support of this model, we found that M1 promoted survival in Saccharomyces cerevisiae overexpressing human Apaf-1 and procaspase-9, critical components of the apoptosome, or overexpressing only conformationally active caspase-9. In mammalian cells, M1 coimmunoprecipitated with Apaf-1-procaspase-9 complexes. The current model is that M1 associates with and allows the formation of the apoptosome but prevents apoptotic functions of the apoptosome. The M1 protein features 14 predicted ankyrin (ANK) repeat domains, and M1 is the first ANK-containing protein reported to use this inhibitory strategy. Since ANK-containing proteins are encoded by many large DNA viruses and found in all domains of life, studies of M1 may lead to a better understanding of the roles of ANK proteins in virus-host interactions.IMPORTANCE Apoptosis selectively eliminates dangerous cells such as virus-infected cells. Poxviruses express apoptosis antagonists to neutralize this antiviral host defense. The vaccinia virus (VACV) M1 ankyrin (ANK) protein, a protein with no previously ascribed function, inhibits apoptosis. M1 interacts with the apoptosome and prevents procaspase-9 processing as well as downstream procaspase-3 cleavage in several cell types and under multiple conditions. M1 is the first poxviral protein reported to associate with and prevent the function of the apoptosome, giving a more detailed picture of the threats VACV encounters during infection. Dysregulation of apoptosis is associated with several human diseases. One potential treatment of apoptosis-related diseases is through the use of designed ANK repeat proteins (DARPins), similar to M1, as caspase inhibitors. Thus, the study of the novel antiapoptosis effects of M1 via apoptosome association will be helpful for understanding how to control apoptosis using either natural or synthetic molecules.

Scratching the Surface: Resurfacing Proteins to Endow New Properties and Function

Protein engineering is an emerging discipline that dovetails modern molecular biology techniques with high-throughput screening, laboratory evolution technologies, and computational approaches to modify sequence, structure, and, in some cases, function and properties of proteins. The ultimate goal is to develop new proteins with improved or designer functions for use in biotechnology, medicine, and basic research. One way to engineer proteins is to change their solvent-exposed regions through focused or random "protein resurfacing." In this review we explain what protein resurfacing is, and discuss recent examples of how this strategy is used to generate proteins with altered or broadened recognition profiles, improved stability, solubility, and expression, cell-penetrating ability, and reduced immunogenicity. Additionally we comment on how these properties can be further improved using chemical resurfacing approaches. Protein resurfacing will likely play an increasingly important role as more biologics enter clinical use, and we present some arguments to support this view.