HRD1-mediated PTEN degradation promotes cell proliferation and hepatocellular carcinoma progression

SYVN1 modulates papillary thyroid carcinoma progression by destabilizing HMGB1

E3 ubiquitin ligase synoviolin (SYVN1) has been reported to participate in many human cancers. This study aimed to investigate SYVN1's roles and molecular pathways in papillary thyroid cancer (PTC). The functions of SYVN1 in PTC were further analyzed using gain- and loss-of-function methods and numerous investigations in cellular function and molecular biology. The findings demonstrated that the overexpression of SYVN1 markedly suppressed the proliferation, migration, and invasion of PTC cell lines (NPA87 and TPC-1). We found that SYVN1 interacted with HMGB1 and promoted its ubiquitination and degradation. In addition, SYVN1 effectively impairs cell proliferation, migration, invasion, and the formation of tumor xenografts in mice models. However, this effect may be partly reversed by overexpressing HMGB1. Thus, SYVN1 may inhibit the proliferation, migration, and invasion of PTC cells by disrupting HMGB1. Consequently, SYVN1 might be considered a promising therapeutic target for PTC.

PTEN: an emerging target in rheumatoid arthritis?

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a critical tumor suppressor protein that regulates various biological processes such as cell proliferation, apoptosis, and inflammatory responses by controlling the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PI3K/AKT) signaling pathway. PTEN plays a crucial role in the pathogenesis of rheumatoid arthritis (RA). Loss of PTEN may contribute to survival, proliferation, and pro-inflammatory cytokine release of fibroblast-like synoviocytes (FLS). Also, persistent PI3K signaling increases myeloid cells' osteoclastic potential, enhancing localized bone destruction. Recent studies have shown that the expression of PTEN protein in the synovial lining of RA patients with aggressive FLS is minimal. Experimental upregulation of PTEN protein expression could reduce the damage caused by RA. Nonetheless, a complete comprehension of aberrant PTEN drives RA progression and its interactions with other crucial molecules remains elusive. This review is dedicated to promoting a thorough understanding of the signaling mechanisms of aberrant PTEN in RA and aims to furnish pertinent theoretical support for forthcoming endeavors in both basic and clinical research within this domain.

Hepatitis B virus core protein stabilizes RANGAP1 to upregulate KDM2A and facilitate hepatocarcinogenesis

PURPOSE

As a vital component of the hepatitis B virus (HBV) nucleocapsid, HBV core protein (HBC) contributes to hepatocarcinogenesis. Here, we aimed to assess the effects of RANGAP1 and KDM2A on tumorigenesis induced by HBC.

METHODS

Co-immunoprecipitation (Co-IP) combined with mass spectrometry were utilized to identify the proteins with the capacity to interact with HBC. The gene and protein levels of RANGAP1 and KDM2A in hepatocellular carcinoma (HCC) and HBV-positive HCC tissues were evaluated using different cohorts. The roles of RANGAP1 and KDM2A in HCC cells mediated by HBC were investigated in vitro and in vivo. Co-IP and western blot were used to estimate the interaction of HBC with RANGAP1 and KDM2A and assess RANGAP1 stabilization regulated by HBC.

RESULTS

We discovered that HBC could interact with RANGAP1 and KDM2A, the levels of which were markedly elevated in HCC tissues. Relying on RANGAP1 and KDM2A, HBC facilitated HCC cell growth and migration. The increased stabilization of RANGAP1 mediated by HBC was relevant to the disruption of the interaction between RANGAP1 and an E3 ligase SYVN1. RANGAP1 interacted with KDM2A, and it further promoted KDM2A stabilization by disturbing the interaction between KDM2A and SYVN1. HBC enhanced the interaction of KDM2A with RANGAP1 and upregulated the expression of KDM2A via RANGAP1 in HCC cells.

CONCLUSIONS

These findings demonstrate a novel mechanism by which HBC facilitates hepatocarcinogenesis. RANGAP1 and KDM2A could act as potential molecular targets for treating HBV-associated malignancy.

Radix Bupleuri-Radix Paeoniae Alba Inhibits the Development of Hepatocellular Carcinoma through Activation of the PTEN/PD-L1 Axis within the Immune Microenvironment

OBJECTIVE

This study investigated how Radix Bupleuri-Radix Paeoniae Alba (BP) was active against hepatocellular carcinoma (HCC).

METHODS

Traditional Chinese medicine systems pharmacology (TCMSP) database was employed to determine the active ingredients of BP and potential targets against HCC. Molecular docking analysis verified the binding activity of PTEN with BP ingredients. H22 cells were used to establish an HCC model in male balb/c mice. Immunofluorescence staining, immunohistochemistry, flow cytometry, western blotting, enzyme-linked immunosorbent assay, and real-time quantitative PCR were used to study changes in proliferation, apoptosis, PTEN levels, inflammation, and T-cell differentiation in male balb/c mice.

RESULTS

The major active ingredients in BP were found to be quercetin, kaempferol, isorhamnetin, stigmasterol, and beta-sitosterol. Molecular docking demonstrated that these five active BP ingredients formed a stable complex with PTEN. BP exhibited an anti-tumor effect in our HCC mouse model. BP was found to increase the CD8+ and IFN-γ+/CD4+ T cell levels while decreasing the PD-1+/CD8+ T and Treg cell levels in HCC mice. BP up-regulated the IL-6, IFN-γ, and TNF-α levels but down-regulated the IL-10 levels in HCC mice. After PTEN knockdown, BP-induced effects were abrogated.

CONCLUSION

BP influenced the immune microenvironment through activation of the PTEN/PD-L1 axis, protecting against HCC.

Deciphering roles of TRIMs as promising targets in hepatocellular carcinoma: current advances and future directions

Tripartite motif (TRIM) family is assigned to RING-finger-containing ligases harboring the largest number of proteins in E3 ubiquitin ligating enzymes. E3 ubiquitin ligases target the specific substrate for proteasomal degradation via the ubiquitin-proteasome system (UPS), which seems to be a more effective and direct strategy for tumor therapy. Recent advances have demonstrated that TRIM genes associate with the occurrence and progression of hepatocellular carcinoma (HCC). TRIMs trigger or inhibit multiple biological activities like proliferation, apoptosis, metastasis, ferroptosis and autophagy in HCC dependent on its highly conserved yet diverse structures. Remarkably, autophagy is another proteolytic pathway for intracellular protein degradation and TRIM proteins may help to delineate the interaction between the two proteolytic systems. In depth research on the precise molecular mechanisms of TRIM family will allow for targeting TRIM in HCC treatment. We also highlight several potential directions warranted further development associated with TRIM family to provide bright insight into its translational values in hepatocellular carcinoma.

HMMR alleviates endoplasmic reticulum stress by promoting autophagolysosomal activity during endoplasmic reticulum stress-driven hepatocellular carcinoma progression

BACKGROUND

The mechanism of hepatitis B virus (HBV)-induced carcinogenesis remains an area of interest. The accumulation of hepatitis B surface antigen in the endoplasmic reticulum (ER) of hepatocytes stimulates persistent ER stress. Activity of the unfolded protein response (UPR) pathway of ER stress may play an important role in inflammatory cancer transformation. How the protective UPR pathway is hijacked by cells as a tool for malignant transformation in HBV-related hepatocellular carcinoma (HCC) is still unclear. Here, we aimed to define the key molecule hyaluronan-mediated motility receptor (HMMR) in this process and explore its role under ER stress in HCC development.

METHODS

An HBV-transgenic mouse model was used to characterize the pathological changes during the tumor progression. Proteomics and transcriptomics analyses were performed to identify the potential key molecule, screen the E3 ligase, and define the activation pathway. Quantitative real-time PCR and Western blotting were conducted to detect the expression of genes in tissues and cell lines. Luciferase reporter assay, chromatin immunoprecipitation, coimmunoprecipitation, immunoprecipitation, and immunofluorescence were employed to investigate the molecular mechanisms of HMMR under ER stress. Immunohistochemistry was used to clarify the expression patterns of HMMR and related molecules in human tissues.

RESULTS

We found sustained activation of ER stress in the HBV-transgenic mouse model of hepatitis-fibrosis-HCC. HMMR was transcribed by c/EBP homologous protein (CHOP) and degraded by tripartite motif containing 29 (TRIM29) after ubiquitination under ER stress, which caused the inconsistent expression of mRNA and protein. Dynamic expression of TRIM29 in the HCC progression regulated the dynamic expression of HMMR. HMMR could alleviate ER stress by increasing autophagic lysosome activity. The negative correlation between HMMR and ER stress, positive correlation between HMMR and autophagy, and negative correlation between ER stress and autophagy were verified in human tissues.

CONCLUSIONS

This study identified the complicated role of HMMR in autophagy and ER stress, that HMMR controls the intensity of ER stress by regulating autophagy in HCC progression, which could be a novel explanation for HBV-related carcinogenesis.

Estrogens drive the endoplasmic reticulum-associated degradation and promote proto-oncogene c-Myc expression in prostate cancer cells by androgen receptor/estrogen receptor signaling

The tumorigenic properties of prostate cancer are regulated by advanced hormonal regulation-mediated complex molecular signals. Therefore, characterizing the regulation of these signal transduction systems is crucial for understanding prostate cancer biology. Recent studies have shown that endoplasmic reticulum (ER)-localized protein quality control mechanisms, including ER-associated degradation (ERAD) and unfolded protein response (UPR) signaling contribute to prostate carcinogenesis and to the development of drug resistance. It has also been determined that these systems are tightly regulated by androgens. However, the role of estrogenic signaling in prostate cancer and its effects on protein quality control mechanisms is not fully understood. Herein, we investigated the regulatory effects of estrogens on ERAD and UPR and their impacts on prostate carcinogenesis. We found that estrogens strongly regulated the ERAD components and IRE1⍺ branch of UPR by Er⍺/β/AR axis. Besides, estrogenic signaling rigorously regulated the tumorigenicity of prostate cancer cells by promoting c-Myc expression and epithelial-mesenchymal transition (EMT). Moreover, estrogenic signal blockage significantly decreased the tumorigenic features of prostate cancer cells. Additionally, simultaneous inhibition of androgenic/estrogenic signals more efficiently inhibited tumorigenicity of prostate cancer cells, including proliferation, migration, invasion and colonial growth. Furthermore, computational-based molecular docking, molecular dynamics simulations and MMPBSA calculations supported the estrogenic stimulation of AR. Present findings suggested that ERAD components and IRE1⍺ signaling are tightly regulated by estrogen-stimulated AR and Er⍺/β. Our data suggest that treatment approaches targeting the co-inhibition of androgenic/estrogenic signals may pave the way for new treatment approaches to be developed for prostate cancer. The present model of the impact of estrogens on ERAD and UPR signaling in androgen-sensitive prostate cancer cells.

Molecular Characterization of Esophageal Squamous Cell Carcinoma Using Quantitative Proteomics

Esophageal squamous cell carcinoma (ESCC) is a heterogeneous cancer associated with a poor prognosis in advanced stages. In India, it is the sixth most common cause of cancer-related mortality. In this study, we employed high-resolution mass spectrometry-based quantitative proteomics to characterize the differential protein expression pattern associated with ESCC. We identified several differentially expressed proteins including PDPN, TOP2A, POSTN and MMP2 that were overexpressed in ESCC. In addition, we identified downregulation of esophagus tissue-enriched proteins such as SLURP1, PADI1, CSTA, small proline-rich proteins such as SPRR3, SPRR2A, SPRR1A, KRT4, and KRT13, involved in squamous cell differentiation. We identified several overexpressed proteins mapped to the 3q24-29 chromosomal region, aligning with CNV alterations in this region reported in several published studies. Among these, we identified overexpression of SOX2, TP63, IGF2BP2 and RNF13 that are encoded by genes in the 3q26 region. Functional enrichment analysis revealed proteins involved in cell cycle pathways, DNA replication, spliceosome, and DNA repair pathways. We identified the overexpression of multiple proteins that play a major role in alleviating ER stress, including SYVN1 and SEL1L. The SYVN1/SEL1L complex is an essential part of the ER quality control machinery clearing misfolded proteins from the ER. SYVN1 is an E3 ubiquitin ligase that ubiquitinates ER-resident proteins. Interestingly, there are also other non-canonical substrates of SYVN1 which are known to play a crucial role in tumor progression. Thus, SYVN1 could be a potential therapeutic target in ESCC.

HRD1 Promotes Non-small Cell Lung Carcinoma Metastasis by Blocking Autophagy-mediated MIEN1 Degradation

Dysregulation of autophagy has been implicated in the development of many diseases, including cancer. Here, we revealed a novel function of the E3 ubiquitin ligase HRD1 in non-small cell lung carcinoma (NSCLC) metastasis by regulating autophagy. Mechanistically, HRD1 inhibits autophagy by promoting ATG3 ubiquitination and degradation. Additionally, a pro-migratory and invasive factor, MIEN1 (migration and invasion enhancer 1), was found to be autophagically degraded upon HRD1 deficiency. Importantly, both HRD1 and MIEN1 expression are upregulated and positively correlated in lung tumors. Based on these results, we proposed a novel mechanism of HRD1 function that the degradation of ATG3 protein by HRD1 leads to autophagy inhibition and MIEN1 release, thus promoting NSCLC metastasis. Therefore, our findings provided new insights into the role of HRD1 in NSCLC metastasis and new therapeutic targets for lung cancer treatment.

Circadian Oscillation Pattern of Endoplasmic Reticulum Quality Control (ERQC) Components in Human Embryonic Kidney HEK293 Cells

The circadian clock regulates the “push-pull” of the molecular signaling mechanisms that arrange the rhythmic organization of the physiology to maintain cellular homeostasis. In mammals, molecular clock genes tightly arrange cellular rhythmicity. It has been shown that this circadian clock optimizes various biological processes, including the cell cycle and autophagy. Hence, we explored the dynamic crosstalks between the circadian rhythm and endoplasmic reticulum (ER)-quality control (ERQC) mechanisms. ER-associated degradation (ERAD) is one of the most important parts of the ERQC system and is an elaborate surveillance system that eliminates misfolded proteins. It regulates the steady-state levels of several physiologically crucial proteins, such as 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and the metastasis suppressor KAI1/CD82. However, the circadian oscillation of ERQC members and their roles in cellular rhythmicity requires further investigation. In the present study, we provided a thorough investigation of the circadian rhythmicity of the fifteen crucial ERQC members, including gp78, Hrd1, p97/VCP, SVIP, Derlin1, Ufd1, Npl4, EDEM1, OS9, XTP3B, Sel1L, Ufd2, YOD1, VCIP135 and FAM8A1 in HEK293 cells. We found that mRNA and protein accumulation of the ubiquitin conjugation, binding and processing factors, retrotranslocation-dislocation, substrate recognition and targeting components of ERQC exhibit oscillation under the control of the circadian clock. Moreover, we found that Hrd1 and gp78 have a possible regulatory function on Bmal1 turnover. The findings of the current study indicated that the expression level of ERQC components is fine-tuned by the circadian clock and major ERAD E3 ligases, Hrd1 and gp78, may influence the regulation of circadian oscillation by modulation of Bmal1 stability.

Downregulation of miR-221-3p promotes the ferroptosis in gastric cancer cells via upregulation of ATF3 to mediate the transcription inhibition of GPX4 and HRD1

BACKGROUND

Gastric cancer (GC) is an aggressive gastrointestinal tumor. MiRNAs participate in the tumorigenesis of GC. Nevertheless, the function of miR-221-3p in GC remains largely unknown.

METHODS

RNA levels were assessed by RT-qPCR. Western blot was performed to test the protein levels. The relation between miR-221-3p and ATF3 was investigated by dual-luciferase reporter assay. ChIP and dual-luciferase reporter assay were applied to assess the interaction between ATF3 and HRD1 or GPX4. Meanwhile, cell proliferation was investigated by CCK8 and colony formation assay. The content of erastin-induced Fe²⁺ was investigated by iron assay kit. Erastin-induced lipid ROS level was assessed by C11-BODIPY 581/591. Co-immunoprecipitation was used to detect the interaction between HRD1 and ACSL4. In addition, xenograft mice model was established to detect the effect of miR-221-3p in GC.

RESULTS

Depletion of miR-221-3p greatly attenuated GC cell proliferation through promoting ferroptosis. Meanwhile, ATF3 was downregulated in GC, and it was identified to be the downstream mRNA of miR-221-3p. MiR-221-3p downregulation could promoted the ferroptosis in GC cells through upregulation of ATF3. HRD1 mediates ubiquitination and degradation of ACSL4 to inhibit ferroptosis. ATF3 upregulation could reduce GC cell proliferation via downregulating the transcription of GPX4 and HRD1. Furthermore, downregulation of miR-221-3p markedly attenuated the growth of GC in mice.

CONCLUSION

HRD1 mediates ubiquitination and degradation of ACSL4 to inhibit ferroptosis. MiR-221-3p depletion upregulates the ferroptosis in GC cells via upregulation of ATF3 to mediate the transcription inhibition of GPX4 and HRD1. Our study might provide a novel target for GC treatment.

GFPT1 promotes the proliferation of cervical cancer via regulating the ubiquitination and degradation of PTEN

Cervical cancer demonstrates the fourth incidence and death rate in females worldwide. Glutamine--fructose-6-phosphate transaminase 1 (GFPT1), the first rate-limited enzyme of the hexosamine biosynthesis pathway, has been reported to promote the progression of cancers. However, the prognostic value and roles of GFPT1 in cervical cancer are largely unknown. Transcription expression data for cervical cancer were downloaded from public databases. GFPT1 overexpressed and knockdown cell lines were constructed. Colony formation assays, Edu assays and 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays were used to measure the proliferation capabilities of cervical cancer cells. Western blot, Immunofluorescence and co-immunoprecipitation assays were performed to verify the interaction between GFPT1and Phosphatase and tensin homolog (PTEN). Animal assays were applied to verify the results in vivo. GFPT1 expression was higher in cervical cancer cell lines. The proliferation capabilities of cervical cancer cells were suppressed in GFPT1 knockdown cells and GFPT1 inhibitor L-DON treated cells. And overexpression of GFPT1 promoted cell proliferation. PTEN was up-regulated in GFPT1 knockdown cells and downregulated in GFPT1 overexpression cells. Immunofluorescence and co-immunoprecipitation results showed that GFPT1 was co-localized and interacted with PTEN. GFPT1 promoted the ubiquitination and degradation of PTEN. Silence of PTEN offsets the growth inhibition of cervical cancer caused by GFPT1 knockdown. Animal assays showed that GFPT1 promoted the proliferation of cervical cancer in vivo. Our study revealed that GFPT1 could promote the progression of cervical cancer by regulating PTEN expression. Our study highlights the GFPT1-PTEN regulation as a potential therapy target for cervical cancer. .

S-palmitoylation of PCSK9 induces sorafenib resistance in liver cancer by activating the PI3K/AKT pathway

Sorafenib is currently the first-line treatment for advanced hepatocellular carcinoma (HCC). However, sorafenib resistance remains a significant challenge. Aberrant AKT signaling activation is a crucial mechanism driving sorafenib resistance in HCC. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a vital role in antitumor immune responses. In this study, we demonstrate that aberrant PCSK9 upregulation promotes cell proliferation and sorafenib resistance in HCC by inducing AKT-S473 phosphorylation. After palmitoylation at cysteine 600, the binding affinity between PCSK9 and tensin homolog (PTEN) is dramatically increased, inducing lysosome-mediated PTEN degradation and subsequent AKT activation. We identify zinc finger DHHC-type palmitoyltransferase 16 (ZDHHC16) as a palmitoyltransferase that promotes PCSK9 palmitoylation at cysteine 600. We also develop a biologically active PCSK9-derived peptide that competitively inhibits PCSK9 palmitoylation, suppressing AKT phosphorylation and augmenting the antitumor effects of sorafenib in HCC.

Circular RNA circRNA-0039459 promotes the migration, invasion, and proliferation of liver cancer cells through the adsorption of miR-432

This study aimed to investigate the molecular mechanism of circular RNA circ-0039459 and its effects on the apoptosis, proliferation, invasion, and migration of hepatocellular carcinoma cells. The expression of circ-0039459, miR-432, and synoviolin 1 (SYVN1) mRNA was determined using real-time quantitative reverse transcription PCR. Cell proliferation was detected by cell counting kit-8 assay, and the apoptosis rate was detected using flow cytometry. Cell migration and invasion were detected using Transwell assay. The expression of E-cadherin, N-cadherin, and vimentin was detected using western blot. The targeting relationship between circ-0039459 and miR-432 as well as that between miR-432 and SYVN1 were detected using the dual-luciferase reporter and RNA pull-down assays. We found that circ-0039459 and SYVN1 mRNA were highly expressed, whereas miR-432 was lowly expressed in hepatocellular carcinoma cells and tissues. After treatment with ribonuclease R or actinomycin D, the expression of linear RNA was reduced, whereas that of circular RNA was not significantly changed. circ-0039459 knockdown or miR-432 overexpression can inhibit cell proliferation, invasion, and migration and the expression of N-cadherin and vimentin proteins in carcinoma cells as well as promote apoptosis and increase the E-cadherin level. circ-0039459 targeted and regulated miR-432, which targeted and regulated SYVN1. The decreased miR-432 expression reversed the effects of circ-0039459 knockout in cancer cells. Furthermore, SYVN1 overexpression reversed the effect of miR-432 overexpression in hepatoma cells. Hence, circ-0039459 can affect the proliferation, apoptosis, migration, and invasion of hepatocellular carcinoma cells through the adsorption of miR-432, thereby regulating the expression of SYVN1.

HRD1 in human malignant neoplasms: Molecular mechanisms and novel therapeutic strategy for cancer

In tumor cells, the endoplasmic reticulum (ER) plays an essential role in maintaining cellular proteostasis by stimulating unfolded protein response (UPR) underlying stress conditions. ER-associated degradation (ERAD) is a critical pathway of the UPR to protect cells from ER stress-induced apoptosis and the elimination of unfolded or misfolded proteins by the ubiquitin-proteasome system (UPS). 3-Hydroxy-3-methylglutaryl reductase degradation (HRD1) as an E3 ubiquitin ligase plays an essential role in the ubiquitination and dislocation of misfolded protein in ERAD. In addition, HRD1 can target other normal folded proteins. In various types of cancer, the expression of HRD1 is dysregulated, and it targets different molecules to develop cancer hallmarks or suppress the progression of the disease. Recent investigations have defined the role of HRD1 in drug resistance in types of cancer. This review focuses on the molecular mechanisms of HRD1 and its roles in cancer pathogenesis and discusses the worthiness of targeting HRD1 as a novel therapeutic strategy in cancer.

Ginsenoside Rb1 alleviates colitis in mice via activation of endoplasmic reticulum-resident E3 ubiquitin ligase Hrd1 signaling pathway

Endoplasmic reticulum (ER) homeostasis is regulated by ER-resident E3 ubiquitin ligase Hrd1, which has been implicated in inflammatory bowel disease (IBD). Ginsenoside Rb1 (GRb1) is the major ginsenoside in ginseng with multiple pharmacological activities. In this study we investigated the role of Hrd1 in IBD and its regulation by GRb1. Two mouse colitis models were established to mimic human IBD: drinking water containing dextran sodium sulfate (DSS) as well as intra-colonic infusion of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS). Colitis mice were treated with GRb1 (20, 40 mg·kg^-1·d^-1, ig) or a positive control drug sulfasalazine (500 mg·kg^-1·d^-1, ig) for 7 days. The model mice showed typical colitis symptoms and pathological changes in colon tissue. In addition to significant inflammatory responses and cell apoptosis in colon tissue, colon epithelial expression of Hrd1 was significantly decreased, the expression of ER stress markers GRP78, PERK, CHOP, and caspase 12 was increased, and the expression of Fas was increased (Fas was removed by Hrd1-induced ubiquitination). These changes were partially, or completely, reversed by GRb1 administration, whereas injection of Hrd1 inhibitor LS102 (50 mg·kg^-1· d^-1, ip, for 6 days) exacerbated colitis symptoms in colitis mice. GRb1 administration not only normalized Hrd1 expression at both the mRNA and protein levels, but also alleviated the ER stress response, Fas-related apoptosis, and other colitis symptoms. In intestinal cell line IEC-6, the expression of Hrd1 was significantly decreased by LPS treatment, but was normalized by GRb1 (200 μM). GRb1 alleviated LPS-induced ER stress and cell apoptosis in IEC-6 cells, and GRb1 action was inhibited by knockdown of Hrd1 using small interfering RNA. In summary, these results reveal a pathological role of Hrd1 in colitis, and provide a novel insight into alternative treatment of colitis using GRb1 activating Hrd1 signaling pathway.

Integrative proteomics reveals the role of E3 ubiquitin ligase SYVN1 in hepatocellular carcinoma metastasis

Background

Tumor metastasis is a major factor for poor prognosis of hepatocellular carcinoma (HCC), but the relationship between ubiquitination and metastasis need to be studied more systematically. We analyzed the ubiquitinome of HCC in this study to have a more comprehensive insight into human HCC metastasis.

Methods

The protein ubiquitination levels in 15 HCC specimens with vascular invasion and 15 without vascular invasion were detected by ubiquitinome. Proteins with significantly different ubiquitination levels between HCCs with and without vascular invasion were used to predict E3 ubiquitin ligases associated with tumor metastasis. The topological network of protein substrates and corresponding E3 ubiquitin ligases was constructed to identify the key E3 ubiquitin ligase. Besides, the growth, migration and invasion ability of LM3 and HUH7 hepatoma cell lines with and without SYVN1 expression interference were measured by cell proliferation assay, subcutaneous tumor assay, umphal vein endothelium tube formation assay, transwell migration and invasion assays. Finally, the interacting proteins of SYVN1 were screened and verified by protein interaction omics, immunofluorescence, and immunoprecipitation. Ubiquitin levels of related protein substrates in LM3 and HUH7 cells were compared in negative control, SYVN1 knockdown, and SYVN1 overexpression groups.

Results

In this study, our whole‐cell proteomic dataset and ubiquitinomic dataset contained approximately 5600 proteins and 12,000 ubiquitinated sites. We discovered increased ubiquitinated sites with shorter ubiquitin chains during the progression of HCC metastasis. In addition, proteomic and ubiquitinomic analyses revealed that high expression of E3 ubiquitin‐protein ligase SYVN1 is related with tumor metastasis. Furthermore, we found that SYVN1 interacted with heat shock protein 90 (HSP90) and impacted the ubiquitination of eukaryotic elongation factor 2 kinase (EEF2K).

Conclusions

The ubiquitination profiles of HCC with and without vascular invasion were significantly different. SYVN1 was the most important E3 ubiquitin‐protein ligase responsible for this phenomenon, and it was related with tumor metastasis and growth. Therefore, SYVN1 might be a potential therapeutic target for HCC.

DAPT suppresses proliferation and migration of hepatocellular carcinoma by regulating the extracellular matrix and inhibiting the Hes1/PTEN/AKT/mTOR signaling pathway

Background

The aim of the present study was to investigate the antitumor properties of N-(N-[3,5-difluorophenacetyl]-1-alanyl)-S-phenylglycine t-butyl ester (DAPT) against hepatocellular carcinoma (HCC), as well as the underlying mechanism.

Methods

Immunohistochemistry and quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay were used to determine the expression of Notch1 in HCC tissues. The expression of Notch1 in 3 HCC cell lines was evaluated by qRT-PCR and Western blot. The proliferation ability of cells was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assays. Flow cytometry and Transwell assay were used to check the apoptosis and migration of HepG2 cells, respectively. Western blot was used to determine the expression level of Notch1, Hes1, Phosphatase and tensin homolog (PTEN), protein kinase B1 (AKT1), phosphorylated AKT1, mammalian target of rapamycin (mTOR), phosphorylated mTOR, intracellular adhesion molecule-1, vascular cell adhesion protein 1, matrix metalloproteinase (MMP)-2, MMP-9, and focal adhesion kinase in cells and tumor tissues. A HepG2 xenograft experiment was conducted to evaluate the in vivo antitumor properties of DAPT.

Results

Notch1 was found to be significantly upregulated in both HCC tissues and cell lines. DAPT significantly inhibited the proliferation and migration of HepG2 cells in a dose-dependent manner, accompanied by the suppression of Notch1/Hes1 signaling, inactivation of AKT/mTOR signaling, downregulation of MMPs, and decreased expression of adhesion molecules. The activation of Notch1/Hes1 or AKT/mTOR signaling removed the inhibitory effect of DAPT on the proliferation and migration of HepG2 cells, as well as the inhibitory properties of DAPT on the expression of MMPs and adhesion molecules. The antitumor properties and regulatory effect of DAPT against the extracellular matrix (ECM) and Hes1/PTEN/AKT/mTOR signaling were verified by the HepG2 xenograft experiments.

Conclusions

DAPT could suppress the proliferation and migration of HCC by regulating the ECM and inhibiting the Hes1/PTEN/AKT/mTOR signaling pathway.

HRD1 attenuates the high uptake of [18F]FDG in hepatocellular carcinoma PET imaging

INTRODUCTION

Due to individual deviations in tumor tissue uptake, the role of [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography (PET) in hepatocellular carcinoma (HCC) diagnosis is limited. β-Hydroxy β-methylglutaryl-CoA reductase degradation 1 (HRD1) plays a key role in clearing misfolded proteins. This study is aimed to investigate the role and mechanism of HRD1 in [¹⁸F]FDG uptake for the diagnosis of HCC.

METHODS

HRD1 expression level was detected using immunohistochemical (IHC) staining in 9 HCC patients. [¹⁸F]FDG PET/CT scans were conducted before treatment. [¹⁸F]FDG uptakes in HRD1 overexpressed and knockdown transgenic models were measured by γ-counter and microPET imaging. The GLUT1-HRD1 complex was examined by co-immunoprecipitation and IHC assays. GLUT1 expression in different cell lines, xenograft models and HCC patients was evaluated by Western blot and IHC assays.

RESULTS

HRD1 was highly expressed in the HCC tumors of patients with low [¹⁸F]FDG uptake, while the HRD1 expression was obviously low in the higher [¹⁸F]FDG uptake group. Both in vitro and in vivo studies found that HRD1 significantly inhibited [¹⁸F]FDG uptake in HCC Huh7 cell lines and animal models. Furthermore, the co-location and interaction of HRD1 with GLUT1 were detected, and the results also indicate that HRD1 could induce the degradation of GLUT1 in vitro and in vivo.

CONCLUSION

HRD1 inhibits the high uptake of [¹⁸F]FDG in HCC tumor cells by inducing degradation of GLUT1, which leads to decreased diagnostic efficiency of [¹⁸F]FDG PET imaging for HCC.

ADVANCES IN KNOWLEDGE

This study suggests that HRD1 inhibits the high uptake of [¹⁸F]FDG in HCC tumor by inducing degradation of GLUT1.

IMPLICATIONS FOR PATIENT CARE

HCC diagnosis with [¹⁸F]FDG PET should be accompanied by determination of HRD1 expression, and patients with high tumor HRD1 expression might be unsuitable for [¹⁸F]FDG PET.

Anti-Warburg effect by targeting HRD1-PFKP pathway may inhibit breast cancer progression

BACKGROUND

Our previous studies have shown that the E3 ubiquitin ligase of HMG-CoA reductase degradation 1 (HRD1) functions as a tumor suppressor, as overexpression of HRD1 suppressed breast cancer proliferation and invasion. However, its role in breast cancer cell glucose metabolism was unclear. Here, our aim was to uncover the role and molecular mechanisms of HRD1 in regulating aerobic glycolysis in breast cancer.

METHODS

The effect of HRD1 on robic glycolysis in breast cancer cells were assessed. Then the proliferation, colony formation ability, invasion and migration of breast cancer cells were evaluated. The relationship between HRD1 and PFKP was validated by Mass spectrometry analysis, immunofluorescence and co-immunoprecipitation. The level of PFKP ubiquitination was measured using ubiquitylation assay. Furthermore, the tumor growth and metastasis in mice xenografts were observed.

RESULTS

We found that upregulation of HRD1 clearly decreased aerobic glycolysis, and subsequently inhibited breast cancer proliferation and invasion. Mass spectrometry analysis results revealed a large HRD1 interactome, which included PFKP (platelet isoform of phosphofructokinase), a critical enzyme involved in the Warburg Effect in breast cancer. Mechanistically, HRD1 interacted and colocalized with PFKP in the cytoplasm, targeted PFKP for ubiquitination and degradation, and ultimately reduced PFKP expression and activity in breast cancer cells. HRD1 inhibited breast cancer growth and metastasis in vivo through a PFKP-dependent way CONCLUSIONS: Our findings reveal a new regulatory role of HRD1 in Warburg effect and provide a key contributor in breast cancer metabolism. Video abstract.

Emerging Role of Ubiquitination in the Regulation of PD-1/PD-L1 in Cancer Immunotherapy

A growing amount of evidence suggests that ubiquitination and deubiquitination of programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) play crucial roles in the regulation of PD-1 and PD-L1 protein stabilization and dynamics. PD-1/PD-L1 is a major coinhibitory checkpoint pathway that modulates immune escape in cancer patients, and its engagement and inhibition has significantly reshaped the landscape of tumor clearance. The abnormal ubiquitination and deubiquitination of PD-1/PD-L1 influence PD-1/PD-L1-mediated immunosuppression. In this review, we describe the ubiquitination- and deubiquitination-mediated modulation of PD-1/PD-L1 signaling through a variety of E3 ligases and deubiquitinating enzymes (DUBs). Moreover, we briefly expound on the anticancer potential of some agents that target related E3 ligases, which further modulate the ubiquitination of PD-1/PD-L1 in cancers. Therefore, this review reveals the development of a highly promising therapeutic approach for cancer immunotherapy by targeting PD-1/PD-L1 ubiquitination.

Long non-coding RNA GAS5 overexpression inhibits M2-like polarization of tumour-associated macrophages in SMCC-7721 cells by promoting PTEN expression

Tumour-associated macrophage (TAM) polarization is associated with hepatocellular carcinoma but the molecular mechanism of this polarization is still unknown. Peripheral blood mononuclear cells were induced to differentiate into M0, M1 and M2 macrophages and TAMs. TAMs were transfected with pcDNA3.1-GAS5, pcDNA3.1-NC, si-GAS5, si-PTEN or si-Ctrl. A human liver cancer cell line (SMCC-7721) was incubated with the modified TAM supernatant. Quantitative real-time PCR and Western blot were performed to detect gene and protein expression. The cell proliferation and invasion properties of the SMCC-7721 cells were detected by MTT and Transwell assays. GAS5 is up-regulated in M1 macrophages and down-regulated in M2 macrophages and TAMs. GAS5 overexpression promoted M1-like polarization of TAMs and inhibited M2-like polarization of TAMs. Moreover, GAS5 promoted the expression of PTEN in TAMs. PTEN-silenced TAM supernatant treatment promoted cell proliferative and invasive properties of the SMCC-7721 cells and diminished the effect of GAS5-overexpressed TAM supernatant on the cell proliferation and invasion by SMCC-7721 cells. Our results demostrared that GAS5 overexpression inhibited M2-like polarization of TAMs by enhancing PTEN expression, thereby inhibiting cell proliferation and invasion by SMCC-7721 cells. Thus, our results suggest that GAS5 may be a new therapeutic target for HCC treatment.

Roles of Farnesyl-Diphosphate Farnesyltransferase 1 in Tumour and Tumour Microenvironments

Farnesyl-diphosphate farnesyltransferase 1 (FDFT1, squalene synthase), a membrane-associated enzyme, synthesizes squalene via condensation of two molecules of farnesyl pyrophosphate. Accumulating evidence has noted that FDFT1 plays a critical role in cancer, particularly in metabolic reprogramming, cell proliferation, and invasion. Based on these advances in our knowledge, FDFT1 could be a potential target for cancer treatment. This review focuses on the contribution of FDFT1 to the hallmarks of cancer, and further, we discuss the applicability of FDFT1 as a cancer prognostic marker and target for anticancer therapy.

Role of Ubiquitination in PTEN Cellular Homeostasis and Its Implications in GB Drug Resistance

Glioblastoma (GB) is the most common and aggressive brain malignancy, characterized by heterogeneity and drug resistance. PTEN, a crucial tumor suppressor, exhibits phosphatase-dependent (PI3K-AKT-mTOR pathway)/independent (nucleus stability) activities to maintain the homeostatic regulation of numerous physiological processes. Premature and absolute loss of PTEN activity usually tends to cellular senescence. However, monoallelic loss of PTEN is frequently observed at tumor inception, and absolute loss of PTEN activity also occurs at the late stage of gliomagenesis. Consequently, aberrant PTEN homeostasis, mainly regulated at the post-translational level, renders cells susceptible to tumorigenesis and drug resistance. Ubiquitination-mediated degradation or deregulated intracellular localization of PTEN hijacks cell growth rheostat control for neoplastic remodeling. Functional inactivation of PTEN mediated by the overexpression of ubiquitin ligases (E3s) renders GB cells adaptive to PTEN loss, which confers resistance to EGFR tyrosine kinase inhibitors and immunotherapies. In this review, we discuss how glioma cells develop oncogenic addiction to the E3s-PTEN axis, promoting their growth and proliferation. Antitumor strategies involving PTEN-targeting E3 ligase inhibitors can restore the tumor-suppressive environment. E3 inhibitors collectively reactivate PTEN and may represent next-generation treatment against deadly malignancies such as GB.

E3 Ubiquitin Ligase HRD1 Promotes Lung Tumorigenesis by Promoting Sirtuin 2 Ubiquitination and Degradation

The NAD-dependent histone deacetylase sirtuin 2 (SIRT2) plays critical roles in mitosis and cell cycle progression and recently was shown to suppress tumor growth and to be downregulated in several types of cancers. However, the underlying mechanism of SIRT2 downregulation remains unknown. In this study, using bioinformatics, gene expression profiling, protein overexpression approaches, and cell migration assays, we showed that E3 ubiquitin ligase 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase degradation 1 (HRD1) interacts with SIRT2 and promotes its ubiquitination and degradation.

The NAD-dependent histone deacetylase sirtuin 2 (SIRT2) plays critical roles in mitosis and cell cycle progression and recently was shown to suppress tumor growth and to be downregulated in several types of cancers. However, the underlying mechanism of SIRT2 downregulation remains unknown. In this study, using bioinformatics, gene expression profiling, protein overexpression approaches, and cell migration assays, we showed that E3 ubiquitin ligase 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase degradation 1 (HRD1) interacts with SIRT2 and promotes its ubiquitination and degradation. Furthermore, we found that HRD1 deficiency induces SIRT2 upregulation and inhibits the growth and tumor formation of lung cancer cells both in vitro and in vivo. Of note, we observed that SIRT2 expression is downregulated in human lung cancer and also negatively correlates with HRD1 expression in these cancers. Additionally, we found that patients with lung adenocarcinoma having lower HRD1 or higher SIRT2 expression levels tend to survive longer. On the basis of these results, we propose a mechanism of lung tumorigenesis that involves HRD1-mediated downregulation of SIRT2 and suggest that interventions targeting HRD1 activity could be a potential therapeutic strategy to treat patients with lung cancer.

Celecoxib attenuates hepatocellular proliferative capacity during hepatocarcinogenesis by modulating a PTEN/NF-κB/PRL-3 pathway

Although the efficacy of celecoxib on various cancer cell behaviors, including aberrant proliferation, in cultured hepatocellular carcinoma (HCC) cells has been demonstrated, whether celecoxib regulates cell proliferation by targeting PRL-3-associated signaling transduction during hepatocarcinogenesis in vivo has been incompletely studied. Here, we investigate the anti-proliferative efficacy of celecoxib in a rapid HCC mouse model established by hydrodynamic transfection of activated AKT and c-Met proto-oncogenes. The results show that celecoxib is effective at delaying the malignant transformation of hepatocytes by reducing the protein expression of Ki67, Cyclin D1 and c-Myc in the AKT/c-Met HCC-bearing mice. Mechanistically, celecoxib increases the protein expression of PTEN and suppresses the protein expression of NF-κB and PRL-3 in the liver of the HCC mice. Using PTEN-silenced and LPS-stimulated approaches in vitro, a mechanism by which celecoxib regulates a PTEN/NF-κB/PRL-3 pathway in HCC cells was illuminated. Altogether, our study demonstrates that celecoxib attenuates the hepatocellular proliferative capacity during hepatocarcinogenesis, which is probably attributable to its regulation of the PTEN/NF-κB/PRL-3 pathway.

Celecoxib modulates the PTEN/NF-κB/PRL-3 pathway during hepatocarcinogenesis in vivo.

Downregulation of miR-183 inhibits the growth of PANC-1 pancreatic cancer cells in vitro and in vivo, and increases chemosensitivity to 5-fluorouracil and gemcitabine

Pancreatic cancer (PC) is a common malignancy with a poorly understood pathogenesis. Currently, the efficacy of anti-PC therapies is insufficient, partially due to the chemoresistance of cancer cells. The present study aimed to elucidate the role of miR-183 in the proliferation, apoptosis, and chemosensitivity to 5-fluorouracil and gemcitabine of human PC cells and the associated mechanisms. PANC-1 cells were transfected with microRNA (miR)-183 inhibitors, and the effect of miR-183 on cell proliferation was evaluated via MTT assay. Apoptosis and cell cycle distribution were determined by flow cytometry. In vivo tumor xenograft models of PANC-1 cells were generated in BALB/c nude mice to examine the effect of miR-183 downregulation on tumor growth. Furthermore, components of the phosphatase and tensin homolog deleted on chromosome ten (PTEN)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway were examined via reverse transcription-quantitative polymerase chain reaction and western blotting in the collected cells. Finally, PANC-1 cells were treated with 5-fluorouracil or gemcitabine and transfected with miR-183 inhibitors, and the viability of cells was determined by MTT assay. The results demonstrated that knockdown of miR-183 could significantly decrease proliferation and promote apoptosis of PANC-1 cells. The cells transfected with miR-183 inhibitors were significantly arrested at the G₁ phase (P<0.01). Furthermore, miR-183 downregulation led to significant decreases in the mRNA levels of PI3K, Akt and B cell lymphoma-2 (Bcl-2) expression (P<0.001), and significant increases in PTEN and Bcl-2 associated X protein expression in PANC-1 cells (P<0.001). Knockdown of miR-183 was able to significantly increase the chemosensitivity of PANC-1 cells to 5-fluorouracil and gemcitabine. These results indicate that downregulation of miR-183 can inhibit the growth of PC cells in vitro and in vivo, and increase cell sensitivity to 5-fluorouracil and gemcitabine through regulating the PTEN/PI3K/Akt signaling pathway.