RA190, a Proteasome Subunit ADRM1 Inhibitor, Suppresses Intrahepatic Cholangiocarcinoma by Inducing NF-KB-Mediated Cell Apoptosis

hRpn13 shapes the proteome and transcriptome through epigenetic factors HDAC8, PADI4, and transcription factor NF-κB p50

The anti-cancer target hRpn13 is a proteasome substrate receptor. However, hRpn13-targeting molecules do not impair its interaction with proteasomes or ubiquitin, suggesting other critical cellular activities. We find that hRpn13 depletion causes correlated proteomic and transcriptomic changes, with pronounced effects in myeloma cells for cytoskeletal and immune response proteins and bone-marrow-specific arginine deiminase PADI4. Moreover, a PROTAC against hRpn13 co-depletes PADI4, histone deacetylase HDAC8, and DNA methyltransferase MGMT. PADI4 binds and citrullinates hRpn13 and proteasomes, and proteasomes from PADI4-inhibited myeloma cells exhibit reduced peptidase activity. When off proteasomes, hRpn13 can bind HDAC8, and this interaction inhibits HDAC8 activity. Further linking hRpn13 to transcription, its loss reduces nuclear factor κB (NF-κB) transcription factor p50, which proteasomes generate by cleaving its precursor protein. NF-κB inhibition depletes hRpn13 interactors PADI4 and HDAC8. Altogether, we find that hRpn13 acts dually in protein degradation and expression and that proteasome constituency and, in turn, regulation varies by cell type.

Adhesion-regulating molecule 1 (ADRM1) can be a potential biomarker and target for bladder cancer

Adhesion-regulating molecule 1 (ADRM1) has been implicated in tumor development, yet its specific role in bladder cancer (BC) remains undefined. This study aimed to elucidate the function of ADRM1 in BC through a combination of bioinformatics analysis and immunohistochemical analysis (IHC). Utilizing R version 3.6.3 and relevant packages, we analyzed online database data. Validation was conducted through IHC data, approved by the Institutional Ethics Committee (Approval No. K20220830). In both paired and unpaired comparisons, ADRM1 expression was significantly elevated in BC tissues compared to adjacent tissues, as evidenced by the results of TCGA dataset and IHC data. Patients with high ADRM1 expression had statistically worse overall survival than those with low ADRM1 expression in TCGA dataset, GSE32548 dataset, GSE32894 dataset, and IHC data. Functional analysis unveiled enrichment in immune-related pathways, and a robust positive correlation emerged between ADRM1 expression and pivotal immune checkpoints, including CD274, PDCD1, and PDCD1LG2. In tumor microenvironment, samples with the high ADRM1 expression contained statistical higher proportion of CD8 + T cells and Macrophage infiltration. Meanwhile, these high ADRM1-expressing samples displayed elevated tumor mutation burden scores and stemness indices, implying potential benefits from immunotherapy. Patients with low ADRM1 expression were sensitive to cisplatin, docetaxel, vinblastine, mitomycin C, and methotrexate. According to the findings from bioinformatics and IHC analyses, ADRM1 demonstrates prognostic significance for BC patients and holds predictive potential for both immunotherapy and chemotherapy responses. This underscores its role as a biomarker and therapeutic target in BC.

The prognostic value of 19S ATPase proteasome subunits in acute myeloid leukemia and other forms of cancer

Introduction

The ubiquitin-proteasome system (UPS) is an intracellular organelle responsible for targeted protein degradation, which represents a standard therapeutic target for many different human malignancies. Bortezomib, a reversible inhibitor of chymotrypsin-like proteasome activity, was first approved by the FDA in 2003 to treat multiple myeloma and is now used to treat a number of different cancers, including relapsed mantle cell lymphoma, diffuse large B-cell lymphoma, colorectal cancer, and thyroid carcinoma. Despite the success, bortezomib and other proteasome inhibitors are subject to severe side effects, and ultimately, drug resistance. We recently reported an oncogenic role for non-ATPase members of the 19S proteasome in chronic myeloid leukemia (CML), acute myeloid leukemia (AML), and several different solid tumors. In the present study, we hypothesized that ATPase members of the 19S proteasome would also serve as biomarkers and putative therapeutic targets in AML and multiple other cancers.

Methods

We used data from The Cancer Genome Atlas (TCGA) and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) available at UALCAN and/or GEPIA2 to assess the expression and prognostic value of proteasome 26S subunit, ATPases 1-6 (PSMC1-6) of the 19S proteasome in cancer. UALCAN was also used to associate PSMC1-6 mRNA expression with distinct clinicopathological features. Finally, cBioPortal was employed to assess genomic alterations of PSMC genes across different cancer types.

Results

The mRNA and protein expression of PSMC1-6 of the 19S proteasome were elevated in several cancers compared with normal controls, which often correlated with worse overall survival. In contrast, AML patients demonstrated reduced expression of these proteasome subunits compared with normal mononuclear cells. However, AML patients with high expression of PSMC2-5 had worse outcomes.

Discussion

Altogether, our data suggest that components of the 19S proteasome could serve as prognostic biomarkers and novel therapeutic targets in AML and several other human malignancies.

Modulation of the ubiquitin-proteasome system by phytochemicals: Therapeutic implications in malignancies with an emphasis on brain tumors

Regarding the multimechanistic nature of cancers, current chemo- or radiotherapies often fail to eradicate disease pathology, and frequent relapses or resistance to therapies occur. Brain malignancies, particularly glioblastomas, are difficult-to-treat cancers due to their highly malignant and multidimensional biology. Unfortunately, patients suffering from malignant tumors often experience poor prognoses and short survival periods. Thus far, significant efforts have been conducted to discover novel and more effective modalities. To that end, modulation of the ubiquitin-proteasome system (UPS) has attracted tremendous interest since it affects the homeostasis of proteins critically engaged in various cell functions, for example, cell metabolism, survival, proliferation, and differentiation. With their safe and multimodal actions, phytochemicals are among the promising therapeutic tools capable of turning the operation of various UPS elements. The present review, along with an updated outline of the role of UPS dysregulation in multiple cancers, provided a detailed discussion on the impact of phytochemicals on the UPS function in malignancies, especially brain tumors.

GMEB2 Promotes the Growth of Colorectal Cancer by Activating ADRM1 Transcription and NF-κB Signalling and Is Positively Regulated by the m6A Reader YTHDF1

Transcription factors are frequently aberrantly reactivated in various cancers, including colorectal cancer (CRC). However, as a transcription factor, the role of GMEB2 in cancer is still unclear, and further studies are needed. Here, we aimed to identify the function and mechanism of GMEB2 in regulating the malignant progression of CRC. GMEB2 was found to be highly expressed in online data analyses. We demonstrated that GMEB2 was markedly upregulated at both the mRNA and protein levels in CRC cells and tissues. GMEB2 knockdown inhibited CRC cell growth in vitro and in vivo. Mechanistically, as a transcription factor, GMEB2 transactivated the ADRM1 promoter to increase its transcription. Rescue experiments showed that ADRM1 downregulation partially reversed the promoting effects of GMEB2 on CRC growth in vitro. Moreover, the GMEB2/ADRM1 axis induced nuclear translocation of NF-κB, thus activating NF-κB signalling. Finally, we further revealed that YTHDF1 recognized and bound to the m⁶A site on GMEB2 mRNA, which enhanced its stability. Taken together, our findings reveal the crucial role and regulatory mechanism of GMEB2 in CRC for the first time and provide a novel potential therapeutic target for CRC therapy.

19S Proteasome Subunits as Oncogenes and Prognostic Biomarkers in FLT3-Mutated Acute Myeloid Leukemia (AML)

26S proteasome non-ATPase subunits 1 (PSMD1) and 3 (PSMD3) were recently identified as prognostic biomarkers and potential therapeutic targets in chronic myeloid leukemia (CML) and multiple solid tumors. In the present study, we analyzed the expression of 19S proteasome subunits in acute myeloid leukemia (AML) patients with mutations in the FMS-like tyrosine kinase 3 (FLT3) gene and assessed their impact on overall survival (OS). High levels of PSMD3 but not PSMD1 expression correlated with a worse OS in FLT3-mutated AML. Consistent with an oncogenic role for PSMD3 in AML, shRNA-mediated PSMD3 knockdown impaired colony formation of FLT3+ AML cell lines, which correlated with increased OS in xenograft models. While PSMD3 regulated nuclear factor-kappa B (NF-κB) transcriptional activity in CML, we did not observe similar effects in FLT3+ AML cells. Rather, proteomics analyses suggested a role for PSMD3 in neutrophil degranulation and energy metabolism. Finally, we identified additional PSMD subunits that are upregulated in AML patients with mutated versus wild-type FLT3, which correlated with worse outcomes. These findings suggest that different components of the 19S regulatory complex of the 26S proteasome can have indications for OS and may serve as prognostic biomarkers in AML and other types of cancers.

Development and Characterization of Human Primary Cholangiocarcinoma Cell Lines

Cholangiocarcinoma (CCA) is the second most common primary liver tumor and is associated with late diagnosis, limited treatment options, and a 5-year survival rate of around 30%. CCA cell lines were first established in 1971, and since then, only 70 to 80 CCA cell lines have been established. These cell lines have been essential in basic and translational research to understand and identify novel mechanistic pathways, biomarkers, and disease-specific genes. Each CCA cell line has unique characteristics, reflecting a specific genotype, sex-related properties, and patient-related signatures, making them scientifically and commercially valuable. CCA cell lines are crucial in the use of novel technologies, such as three-dimensional organoid models, which help to model the tumor microenvironment and cell-to-cell crosstalk between tumor-neighboring cells. This review highlights crucial information on CCA cell lines, including: i) type of CCA (eg, intra- or extrahepatic), ii) isolation source (eg, primary tumor or xenograft), iii) chemical digestion method (eg, trypsin or collagenase), iv) cell-sorting method (colony isolation or removal of fibroblasts), v) maintenance-medium choice (eg, RPMI or Dulbecco's modified Eagle's medium), vi) cell morphology (eg, spindle or polygonal shape), and vii) doubling time of cells.

Roles of ubiquitination in the crosstalk between tumors and the tumor microenvironment (Review)

The interaction between a tumor and the tumor microenvironment (TME) plays a key role in tumorigenesis and tumor progression. Ubiquitination, a crucial post-translational modification for regulating protein degradation and turnover, plays a role in regulating the crosstalk between a tumor and the TME. Thus, identifying the roles of ubiquitination in the process may assist researchers to investigate the mechanisms underlying tumorigenesis and tumor progression. In the present review article, new insights into the substrates for ubiquitination that are involved in the regulation of hypoxic environments, angiogenesis, chronic inflammation-mediated tumor formation, and the function of cancer-associated fibroblasts and infiltrating immune cells (tumor-associated macrophages, T-cells, myeloid-derived suppressor cells, dendritic cells, and natural killer cells) are summarized. In addition, the potential targets of the ubiquitination proteasome system within the TME for cancer therapy and their therapeutic effects are reviewed and discussed.

Development of a prognostic signature of patients with esophagus adenocarcinoma by using immune-related genes

Background

Esophageal adenocarcinoma (EAC) is an aggressive malignancy with a poor prognosis. The immune-related genes (IRGs) are crucial to immunocytes tumor infiltration. This study aimed to construct a IRG-related prediction signature in EAC.

Methods

The related data of EAC patients and IRGs were obtained from the TCGA and ImmPort database, respectively. The cox regression analysis constructed the prediction signature and explored the transcription factors regulatory network through the Cistrome database. TIMER database and CIBERSORT analytical tool were utilized to explore the immunocytes infiltration analysis.

Results

The prediction signature with 12 IRGs (ADRM1, CXCL1, SEMG1, CCL26, CCL24, AREG, IL23A, UCN2, FGFR4, IL17RB, TNFRSF11A, and TNFRSF21) was constructed. Overall survival (OS) curves indicate that the survival rate of the high-risk group is significantly shorter than the low-risk group (P = 7.26e−07), and the AUC of 1-, 3- and 5- year survival prediction rates is 0.871, 0.924, and 0.961, respectively. Compared with traditional features, the ROC curve of the risk score in the EAC patients (0.967) is significant than T (0.57), N (0.738), M (0.568), and Stage (0.768). Moreover, multivariate Cox analysis and Nomogram of risk score are indicated that the 1-year and 3-year survival rates of patients are accurate by the combined analysis of the risk score, Sex, M stage, and Stage (The AUC of 1- and 3-years are 0.911, and 0.853).

Conclusion

The 12 prognosis-related IRGs might be promising therapeutic targets for EAC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-021-04456-2.

The Application Progress of Patient-Derived Tumor Xenograft Models After Cholangiocarcinoma Surgeries

Surgical treatment is the only possible cure for cholangiocarcinoma (CCA) at present. However, the high recurrence rate of postoperative CCA leads to a very poor prognosis for patients, effective postoperative chemotherapy is hence the key to preventing the recurrence of CCA. The sensitivity of CCA to cytotoxic chemotherapy drugs and targeted drugs varies from person to person, and therefore, the screening of sensitive drugs has become an important topic after CCA surgeries. Patient-Derived tumor Xenograft models (PDX) can stably retain the genetic and pathological characteristics of primary tumors, and better simulate the tumor microenvironment of CCA. The model is also of great significance in screening therapeutic targeted drugs after CCA, analyzing predictive biomarkers, and improving signal pathways in prognosis and basic research. This paper will review the current established methods and applications of the patient-derived tumor xenograft model of cholangiocarcinoma, aiming to provide new ideas for basic research and individualized treatment of cholangiocarcinoma after surgery.

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.

ADRM1 as a therapeutic target in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a primary liver tumor, is the third leading cause of cancer-related mortality worldwide. The proteasome system is overactivated in the majority of tumors, including HCC. However, targeting the proteasome system in HCC is not as effective as in other types of cancer. Therefore, a new target of HCC therapy needs to be identified, and the potential mechanism must be studied. Using the The Cancer Gene Genome Atlas and GEO datasets, the present investigation demonstrated for the first time that ADRM1 is overexpressed in HCC, and the high level of its expression predicts poor overall survival in HCC patients. The high expression of ADRM1 in HCC was verified using tumor tissue arrays. By comparing paired tumor and nontumor tissues, it was shown that the majority of HCC patients (76.25%) exhibited higher ADRM1 expression in the tumor than in normal tissues. in vitro experiments demonstrated that targeting ADRM1 with shRNAs significantly suppressed the proliferation of HCC cells. RA190, a specific inhibitor of ADRM1, suppressed cell proliferation and colony formation by HCC cells in a concentration-dependent manner. The study of the mechanism of the effects of RA190 revealed that targeting ADRM1 blocked the G2/M transition in the cell cycle and induced apoptosis of HCC cells. Together, the obtained results indicate that ADRM1 is a promising target for HCC therapy and suggest that ADRM1 inhibitors, such as RA190, have the potential for clinical application in the treatment of HCC.

Bis-benzylidine Piperidone RA190 treatment of hepatocellular carcinoma via binding RPN13 and inhibiting NF-κB signaling

BACKGROUND

According to GLOBOSCAN, hepatocellular carcinoma (HCC) claimed 782,000 lives in 2018. The tyrosine kinase inhibitor sofafenib is used to treat HCC, but new anticancer agents targeting different pathways are urgently needed to improve outcomes for patients with advanced disease. The aberrant metabolism and aggressive growth of cancer cells can render them particularly susceptible to proteasome inhibition, as demonstrated by bortezomib treatment of multiple myeloma. However, resistance does emerge, and this 20S proteasome inhibitor has not proven active against HCC. The bis-benzylidine piperidone RA190 represents a novel class of proteasome inhibitor that covalently binds to cysteine 88 of RPN13, an ubiquitin receptor subunit of the proteasome's 19S regulatory particle. RA190 treatment inhibits proteasome function, causing rapid accumulation of polyubiquitinated proteins. Considerable evidence suggests that nuclear factor κB (NF-κB) signaling, which is dependent upon the proteasome, is a major driver of inflammation-associated cancers, including HCC.

METHODS

Human HCC cell lines were treated with titrations of RA190. The time course of endoplasmic reticulum stress and NF-κB-related mechanisms by which RA190 may trigger apoptosis were assessed. The therapeutic activity of RA190 was also determined in an orthotopic HCC xenograft mouse model.

RESULTS

RA190 is toxic to HCC cells and synergizes with sofafenib. RA190 triggers rapid accumulation of polyubiquitinated proteins, unresolved endoplasmic reticulum stress, and cell death via apoptosis. RA190 blocks proteasomal degradation of IκBα and consequent release of NF-κB into the nuclei of HCC cells. Treatment of mice bearing an orthotopic HCC model with RA190 significantly reduced tumor growth.

CONCLUSIONS

RA190 has therapeutic activity in a xenograft model, and with sorafenib exhibited synergetic killing of HCC cells in vitro, suggesting further exploration of such a combination treatment of HCC is warranted.

The CCDC43-ADRM1 axis regulated by YY1, promotes proliferation and metastasis of gastric cancer

Previous studies have shown an association between coiled-coil domain-containing (CCDC) genes and different cancers. Our previous studies revealed that CCDC43 is highly expressed in colorectal cancer, but the expression and molecular mechanisms of CCDC43 in gastric cancer (GC) are yet to be determined. Here, we show that CCDC43 is overexpressed in gastric tissues. CCDC43 expression is closely related to tumor differentiation, lymph-node-metastasis, and prognosis of gastric cancer. Overexpression of CCDC43 promotes the proliferation, invasion, and metastasis of GC cells. CCDC43 may upregulate and stabilize ADRM1, resulting in the construction of the ubiquitin-mediated proteasome. In contrast, inhibition of ADRM1 could reverse the function of CCDC43 in GC both in vitro and in vivo. Our data demonstrate that transcription factor YY1 directly binds to CCDC43 and ADRM1 gene promoters, leading to over-expression of CCDC43 and ADRM1. Furthermore, in vitro experiments demonstrate that knock down of CCDC43 or ADRM1 attenuates the YY1-mediated malignant phenotypes. Finally, the association among YY1, CCDC43 and ADRM1 is validated in clinical samples. Our findings suggest that the CCDC43-ADRM1 axis regulated by YY1, promotes proliferation and metastasis of GC, and the axis may be a potential therapeutic target for GC.

Structure-function analyses of candidate small molecule RPN13 inhibitors with antitumor properties

We sought to design ubiquitin-proteasome system inhibitors active against solid cancers by targeting ubiquitin receptor RPN13 within the proteasome’s 19S regulatory particle. The prototypic bis-benzylidine piperidone-based inhibitor RA190 is a michael acceptor that adducts Cysteine 88 of RPN13. In probing the pharmacophore, we showed the benefit of the central nitrogen-bearing piperidone ring moiety compared to a cyclohexanone, the importance of the span of the aromatic wings from the central enone-piperidone ring, the contribution of both wings, and that substituents with stronger electron withdrawing groups were more cytotoxic. Potency was further enhanced by coupling of a second warhead to the central nitrogen-bearing piperidone as RA375 exhibited ten-fold greater activity against cancer lines than RA190, reflecting its nitro ring substituents and the addition of a chloroacetamide warhead. Treatment with RA375 caused a rapid and profound accumulation of high molecular weight polyubiquitinated proteins and reduced intracellular glutathione levels, which produce endoplasmic reticulum and oxidative stress, and trigger apoptosis. RA375 was highly active against cell lines of multiple myeloma and diverse solid cancers, and demonstrated a wide therapeutic window against normal cells. For cervical and head and neck cancer cell lines, those associated with human papillomavirus were significantly more sensitive to RA375. While ARID1A-deficiency also enhanced sensitivity 4-fold, RA375 was active against all ovarian cancer cell lines tested. RA375 inhibited proteasome function in muscle for >72h after single i.p. administration to mice, and treatment reduced tumor burden and extended survival in mice carrying an orthotopic human xenograft derived from a clear cell ovarian carcinoma.

Pterostilbene, An Active Constituent of Blueberries, Suppresses Proliferation Potential of Human Cholangiocarcinoma via Enhancing the Autophagic Flux

Background: Human cholangiocarcinoma (CCA) is a highly lethal cancer that occurs in the biliary tract. It is characterized by early invasion, poor outcomes, and resistance to current chemotherapies. To date, an effective therapeutic strategy for this devastating and deadly disease is lacking. Pterostilbene, a natural compound found in the extracts of many plants including blueberries, kino tree, or dragon blood tree, has several health benefits. However, its effects on CCA have not been clarified. Here, we investigated the potential application of pterostilbene for the treatment of human CCA in vitro and in vivo.

Methods: The effects of pterostilbene on CCA cells were determined by assessing cell viability (CCK), cell proliferation, and colony formation. Cell cycle arrest and apoptosis were measured by flow cytometric analysis, whereas proteins related to autophagy were detected by immunofluorescence and immunoblotting assays. A well-established xenograft mouse model was used to evaluate the effects of pterostilbene on tumor growth in vivo.

Results: Pterostilbene induced dose-dependent and time-dependent cytotoxic effects, inhibited proliferation and colony formation, and caused S phase cell cycle arrest in CCA cells. Instead of triggering apoptotic cell death in these cells, pterostilbene was found to exert potent autophagy-inducing effects, and this correlated with p62 downregulation, elevated expression of endogenous Beclin-1, ATG5, and LC3-II, and increases in LC3 puncta. Pretreating cancer cells with the autophagy inhibitor 3-MA suppressed the induction of autophagy and antitumor activity caused by pterostilbene. Finally, we confirmed that pterostilbene inhibited tumor growth in a CCA xenograft mouse model with minimal general toxicity.

Conclusion: Taken together, our findings indicate that pterostilbene, through the induction of autophagic flux, acts as an anti-cancer agent against CCA cells.

LRP6 regulates Rab7-mediated autophagy through the Wnt/β-catenin pathway to modulate trophoblast cell migration and invasion

Pre-eclampsia is a common complication during pregnancy; however, the underlying mechanisms of the crosstalk between low-density lipoprotein receptor-related protein 6 (LRP6) and autophagy in trophoblast cells are still not fully explored. Messenger RNA (mRNA) and protein levels of LRP6, beclin 1, Unc-51-like autophagy activating kinase 1 (ULK1), p62, vimentin, matrix metallopeptidase-9 (MMP-9), β-catenin, c-Myc, and Rab7, as well as the ratio of LC3-II/LC3-I, were analysed by quantitative real-time polymerase chain reaction or Western blot analysis, respectively. An MTT assay was used to measure cell growth, and transwell and wound healing assays were carried out to evaluate the invasion and migration abilities of the trophoblasts used. An immunofluorescence assay was used to measure LC3. The mRFP-GFP-LC3 tandem fluorescence assay was applied to detect autophagic flow. LRP6 overexpression was achieved by constructing pcDNA3.1-LRP6 vectors. LRP6 was expressed at low levels in HTR-8/SVneo cells under hypoxia/reoxygenation (H/R) conditions. H/R inhibited the activation of autophagy. LRP6 overexpression promoted cell proliferation and activated autophagy, which led to the upregulation of beclin 1 and ULK1, as well as the ratio of LC3-II/LC3-I and the downregulation of p62. Furthermore, LRP6 overexpression elevated the migration and invasion abilities of the indicated cells and increased vimentin and MMP-9 expression levels. Furthermore, LRP6 upregulated Rab7 and activated autophagy through the Wnt/β-catenin pathway. The late autophagy inhibitor bafilomycin A1 (Baf-A1) and the Wnt/β-catenin pathway inhibitor PKF115-584 reversed the effects of LRP6 on trophoblast autophagy, migration and invasion. LRP6 promotes Rab7-mediated autophagy by activating the Wnt/β-catenin pathway, which leads to increasing migration and invasion of trophoblast cells. Our study paves a new avenue for clinical treatment, and LRP6 may serve as an essential target in pre-eclampsia.

Context-Dependent Role of NF-κB Signaling in Primary Liver Cancer-from Tumor Development to Therapeutic Implications

Chronic inflammatory cell death is a major risk factor for the development of diverse cancers including liver cancer. Herein, disruption of the hepatic microenvironment as well as the immune cell composition are major determinants of malignant transformation and progression in hepatocellular carcinomas (HCC). Considerable research efforts have focused on the identification of predisposing factors that promote induction of an oncogenic field effect within the inflammatory liver microenvironment. Among the most prominent factors involved in this so-called inflammation-fibrosis-cancer axis is the NF-κB pathway. The dominant role of this pathway for malignant transformation and progression in HCC is well documented. Pathway activation is significantly linked to poor prognostic traits as well as stemness characteristics, which places modulation of NF-κB signaling in the focus of therapeutic interventions. However, it is well recognized that the mechanistic importance of the pathway for HCC is highly context and cell type dependent. While constitutive pathway activation in an inflammatory etiological background can significantly promote HCC development and progression, absence of NF-κB signaling in differentiated liver cells also significantly enhances liver cancer development. Thus, therapeutic targeting of NF-κB as well as associated family members may not only exert beneficial effects but also negatively impact viability of healthy hepatocytes and/or cholangiocytes, respectively. The review presented here aims to decipher the complexity and paradoxical functions of NF-κB signaling in primary liver and non-parenchymal cells, as well as the induced molecular alterations that drive HCC development and progression with a particular focus on (immune-) therapeutic interventions.

Small-Molecule Inhibitors of the Proteasome's Regulatory Particle

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

Non‑covalent proteasome inhibitor PI‑1840 induces apoptosis and autophagy in osteosarcoma cells

Osteosarcoma (OS) is the predominant form of primary bone malignancy in children and adolescents. Although the combination of chemotherapy and modified surgical therapy leads to marked improvements in the survival rate, the therapeutic outcomes remain unsatisfactory. Therefore, the identification of novel drugs with higher efficacy and fewer side‑effects is urgently required. Proteasome inhibitors have been approved by the Food and Drug Administration (FDA) for the treatment of certain cancers, although none of them are directed against OS. Non‑covalent proteasome inhibitors, such as PI‑1840, are superior to covalent ones in numerous respects in view of their chemical structure; however, to date, no studies have been published on the effects of non‑covalent proteasome inhibitors on OS cells. In the present study, the antineoplastic effects of PI‑1840 were systematically evaluated in the OS cell lines, MG‑63 and U2‑OS. Cell viability and morphological changes were assessed by Cell Counting Kit‑8 (CCK‑8) and live/dead assays. The cell cycle was analyzed using flow cytometry (FCM) and western blot analysis (assessing the levels of the proteins p21, p27, and the tyrosine kinase, WEE1). The extent of cell apoptosis and autophagy were assessed by FCM, western blot analysis [of the apoptosis‑associated proteins, microtubule‑associated protein 1 light chain 3 α (LC3) and Beclin1], and mRFP‑GFP‑LC3 adenovirus transfection assay. Transwell and wound healing assays, and western blot analysis of the matrix metalloproteinases (MMPs)2 and 9 were performed to preliminarily evaluate the migration and invasion capability of the cells. In the present study, our results revealed that PI‑1840 inhibited the proliferation of OS cells and induced apoptosis, partly due to attenuation of the nuclear factor‑κB (NF‑κB) pathway. In addition, PI‑1840‑induced autophagy was detected, and inhibiting the autophagy of the OS cells led to an increase in the survival rate of the U2‑OS cells rather than of the MG‑63 cells. Furthermore, PI‑1840 attenuated the migration and invasion capabilities of the OS cells. In conclusion, the present study revealed PI‑1840 to be a promising drug for the treatment of OS.

MEK inhibition suppresses K-Ras wild-type cholangiocarcinoma in vitro and in vivo via inhibiting cell proliferation and modulating tumor microenvironment

PD901, a MEK inhibitor, has been demonstrated of therapeutic efficacy against cholangiocarcinoma (CCA) harboring K-Ras oncogenic mutations. However, most CCA exhibit no K-Ras mutations. In the current study, we investigated the therapeutic potential of PD901, either alone or in combination with the pan-mTOR inhibitor MLN0128, for the treatment of K-Ras wild-type CCA in vitro using human CCA cell lines, and in vivo using AKT/YapS127A CCA mouse model. We discovered that in vitro, PD901 treatment strongly inhibited CCA cell proliferation, and combined PD901 and MLN0128 therapy further increased growth inhibition. In vivo, treatment of PD901 alone triggered tumor regression, which was not further increased when the two drugs were administered simultaneously. Mechanistically, PD901 efficiently hampered ERK activation in vitro and in vivo, leading to strong inhibition of CCA tumor cell cycle progression. Intriguingly, we discovered that PD901, but not MLN0128 treatment resulted in changes affecting the vasculature and cancer-associated fibroblasts in AKT/YapS127A mouse lesions. It led to the decreased hypoxia within tumor lesions, which may further enhance the anti-cell proliferation activities of PD901. Altogether, our study demonstrates that MEK inhibitors could be effective for the treatment of K-Ras wild-type CCA via inhibiting cell proliferation and modulating tumor microenvironment.