Silencing of COPB2 inhibits the proliferation of gastric cancer cells and induces apoptosis via suppression of the RTK signaling pathway

A single C-terminal residue controls SARS-CoV-2 spike trafficking and incorporation into VLPs

The spike (S) protein of SARS-CoV-2 is delivered to the virion assembly site in the ER-Golgi Intermediate Compartment (ERGIC) from both the ER and cis-Golgi in infected cells. However, the relevance and modulatory mechanism of this bidirectional trafficking are unclear. Here, using structure-function analyses, we show that S incorporation into virus-like particles (VLP) and VLP fusogenicity are determined by coatomer-dependent S delivery from the cis-Golgi and restricted by S-coatomer dissociation. Although S mimicry of the host coatomer-binding dibasic motif ensures retrograde trafficking to the ERGIC, avoidance of the host-like C-terminal acidic residue is critical for S-coatomer dissociation and therefore incorporation into virions or export for cell-cell fusion. Because this C-terminal residue is the key determinant of SARS-CoV-2 assembly and fusogenicity, our work provides a framework for the export of S protein encoded in genetic vaccines for surface display and immune activation.

Lysine demethylase 5A promotes prostate adenocarcinoma progression by suppressing microRNA-330-3p expression and activating the COPB2/PI3K/AKT axis in an ETS1-dependent manner

Lysine demethylase 5A (KDM5A) is a histone demethylase frequently involved in cancer progression. This research aimed to explore the function of KDM5A in prostate adenocarcinoma (PRAD) and the molecular mechanism. KDM5A was highly expressed in collected PRAD tissues and acquired PRAD cells. High KDM5A expression was correlated with reduced survival and poor prognosis of patients with PRAD. Knockdown of KDM5A suppressed the proliferation, colony formation, migration, and invasiveness of PRAD cells and reduced angiogenesis ability of endothelial cells. Downstream molecules implicated in KDM5A mediation were predicted using integrated bioinformatic analyses. KDM5A enhanced ETS proto-oncogene 1 (ETS1) expression through demethylation of H3K4me2 at its promoter. ETS1 suppressed the transcription activity of miR-330-3p, and either further ETS1 overexpression or miR-330-3p inhibition blocked the functions of KDM5A knockdown in PRAD. miR-330-3p targeted coatomer protein complex subunit β2 (COPB2) mRNA. Downregulation of miR-330-3p restored the expression of COPB2 and activated the PI3K/AKT pathway in PRAD. The results in vitro were reproduced in vivo where KDM5A downregulation suppressed the growth and metastasis of xenograft tumors in nude mice. In conclusion, this study demonstrated that KDM5A promoted PRAD by suppressing miR-330-3p and activating the COPB2/PI3K/AKT axis in an ETS1-dependent manner.

Depletion of COPI in cancer cells: the role of reactive oxygen species in the induction of lipid accumulation, noncanonical lipophagy and apoptosis

The coatomer protein complex 1 (COPI) is a multisubunit complex that coats intracellular vesicles and is involved in intracellular protein trafficking. Recently we and others found that depletion of COPI complex subunits zeta (COPZ1) and delta (ARCN1) preferentially kills tumor cells relative to normal cells. Here we delineate the specific cellular effects and sequence of events of COPI complex depletion in tumor cells. We find that this depletion leads to the inhibition of mitochondrial oxidative phosphorylation and the elevation of reactive oxygen species (ROS) production, followed by accumulation of lipid droplets (LDs) and autophagy-associated proteins LC3-II and SQSTM1/p62 and, finally, apoptosis of the tumor cells. Inactivation of ROS in COPI-depleted cells with the mitochondrial-specific quencher, mitoquinone mesylate, attenuated apoptosis and markedly decreased both the size and the number of LDs. COPI depletion caused ROS-dependent accumulation of LC3-II and SQSTM1 which colocalizes with LDs. Lack of double-membrane autophagosomes and insensitivity to Atg5 deletion suggested an accumulation of a microlipophagy complex on the surface of LDs induced by depletion of the COPI complex. Our findings suggest a sequence of cellular events triggered by COPI depletion, starting with inhibition of oxidative phosphorylation, followed by ROS activation and accumulation of LDs and apoptosis.

Implication of COPB2 Expression on Cutaneous Squamous Cell Carcinoma Pathogenesis

Simple Summary

The present study aimed to evaluate the effect of COPB2 expression on cutaneous squamous cell carcinoma (cSCC) pathogenesis. cSCC, a common category of skin cancer, is marked by a reasonably favorable prognosis. However, there has been a steady rise in the annual incidence of cases; in particular, a subset of cases showed aggressive progression. However, the underlying molecular mechanism of cSCC pathogenesis is largely unknown. In the present study, we found that COPB2 may act as a potential oncogene and modulator of the tumor immune microenvironment in cSCC pathogenesis. Therefore, COPB2 can serve as a novel predictive prognostic biomarker and immunotherapeutic target in cSCC patients.

Abstract

The underlying molecular mechanisms of cutaneous squamous cell carcinoma (cSCC) pathogenesis are largely unknown. In the present study, we aimed to evaluate the effect of coatomer protein complex subunit beta 2 (COPB2) expression on cSCC pathogenesis. Clinicopathological significance of COPB2 in cSCC was investigated by analyzing the Gene Expression Omnibus (GEO) database and through a retrospective cohort study of 95 cSCC patients. The effect of COPB2 expression on the biological behavior of cSCC cells was investigated both in vitro and in vivo. We found that COPB2 expression was significantly higher in cSCC samples than in normal skin samples. In our cohort, a considerable association was found between COPB2 expression and indicators of tumor immune microenvironment (TIME), such as histocompatibility complex class (MHC) I, and MHC II, CD4+/ CD8+ tumor-infiltrating lymphocytes. Additionally, COPB2 expression had an independent impact on worsened recurrence-free survival in our cohort. Furthermore, decreased proliferation, invasion, tumorigenic activities, and increased apoptosis were observed after COPB2 knockdown in cSCC cells. COPB2 may act as a potential oncogene and candidate modulator of the TIME in cSCC. Therefore, it can serve as a novel predictive prognostic biomarker and candidate immunotherapeutic target in cSCC patients.

COPB2: a transport protein with multifaceted roles in cancer development and progression

The Coatomer protein complex subunit beta 2 (COPB2) is involved in the formation of the COPI coatomer protein complex and is responsible for the transport of vesicles between the Golgi apparatus and the endoplasmic reticulum. It plays an important role in maintaining the integrity of these cellular organelles, as well as in maintaining cell homeostasis. More importantly, COPB2 plays key roles in embryonic development and tumor progression. COPB2 is regarded as a vital oncogene in several cancer types and has been implicated in tumor cell proliferation, survival, invasion, and metastasis. Here, we summarize the current knowledge on the roles of COPB2 in cancer development and progression in the context of the hallmarks of cancer.

Silencing the COPB2 gene decreases the proliferation, migration and invasion of human triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is highly invasive, has a high rate of recurrence and is associated with a poor clinical outcome when compared with non-TNBC due to a lack of effective and targeted treatments. The coatomer protein complex subunit β2 (COPB2) is upregulated in various types of malignant cancer. The present study demonstrated that COPB2 expression levels were significantly upregulated in breast carcinoma HS-578T cells (clonal cells originating from TNBC) when compared with non-TNBC MCF-7 cells. HS-578T cells also exhibited higher rates of proliferation, invasion and transendothelial migration when compared with MCF-7 cells. Moreover, it was identified that genetically silencing the COPB2 gene using a lentivirus-short hairpin RNA inhibited the proliferative, colony formation, migratory and invasive properties of the TNBC HS-578T cells. Mediation of the COPB2 silencing effect may be associated with regulating the phosphorylation of serine/threonine kinase AKT in the PI3K/AKT signaling pathway. These results suggested the importance of COPB2 in promoting the proliferation of TNBC cells and identified COPB2 as a potential novel therapeutic target.

COPB2: A Novel Prognostic Biomarker That Affects Progression of HCC

Purpose

This study is aimed at investigating the expression, underlying biological function, and clinical significance of coatomer protein complex subunit beta 2 (COPB2) in hepatocellular carcinoma (HCC).

Methods

HCC-related data were extracted from The Cancer Genome Atlas (TCGA) database, International Cancer Genome Consortium (ICGC) database, and Gene Expression Omnibus (GEO) database. A logistic regression module was applied to analyze the relationship between the expression of COPB2 and clinicopathologic characteristics. The Cox proportional hazard regression model and Kaplan–Meier method were used for survival analysis. Gene set enrichment analysis (GSEA) was used to annotate the underlying biological functions. Loss-of-function experiments were conducted to determine the underlying mechanisms.

Results

COPB2 was overexpressed in HCC, and high expression of COPB2 was significantly correlated with higher alpha fetoprotein (AFP) (odds ratio (OR) = 1.616, >20 vs. ≤20, p < 0.05), stage (OR = 1.744, III vs. I, p < 0.05), and grade (OR = 1.746, G4+G3 vs. G2+G1, p < 0.05). Kaplan–Meier survival analysis showed that HCC patients with high COPB2 expression had a worse prognosis than those with low COPB2 expression (p < 0.0001 for TCGA cohort, p < 0.05 for ICGC cohort). The univariate Cox (hazard ratio (HR) = 1.068, p < 0.0001) and multivariate Cox (HR = 2.011, p < 0.05) regression analyses suggested that COPB2 was an independent risk factor. GSEA showed that mTOR and other tumor-related signaling pathways were differentially enriched in the high COPB2 expression phenotype. Silencing of COPB2 inhibited the proliferation, migration, and invasion abilities by suppressing epithelial-mesenchymal transition and mTOR signaling.

Conclusion

COPB2 is a novel prognostic biomarker and a promising therapeutic target for HCC.

COPB2 gene silencing inhibits colorectal cancer cell proliferation and induces apoptosis via the JNK/c-Jun signaling pathway

Objectives

Colorectal cancer (CRC) is one of the most common malignant human tumors. It is associated with high morbidity and mortality rates. In recent years, tumor gene therapy has emerged as a promising new approach for colorectal cancer therapy. Herein, we identify and analyze the role of COPB2 (coatomer protein complex, subunit beta 2) in proliferation and apoptosis of CRC cells.

Methods

To investigate the role of COPB2 in the proliferation and apoptosis of CRC cells, a shCOPB2 vector and a shCtrl vector were constructed for transfection into RKO and HCT116 cells. Cells proliferation was subsequently measured via cell counting kit-8 (CCK8) assay and Celigo cell counting assay. Apoptosis was measured via flow cytometry. The activity level of Caspase 3/7 was measured. Finally, the level of several JNK/c-Jun apoptosis pathway-related proteins were measured to characterize the mechanism of apoptosis.

Results

Our results showed that the proliferation rate was decreased and the apoptosis rate was increased in shCOPB2-treated RKO and HCT116 cells compared to those in controls. After the silencing of COPB2, JNK/c-Jun signal pathway activation was increased, the expression levels of apoptosis pathway-related proteins, such as Bad, p53 and Caspase 3, were also increased.

Conclusion

COPB2 gene silencing can inhibit RKO and HCT116 cells proliferation and induce apoptosis via the JNK/c-Jun signaling pathway.

The Yin and Yang of Autosomal Recessive Primary Microcephaly Genes: Insights from Neurogenesis and Carcinogenesis

The stem cells of neurogenesis and carcinogenesis share many properties, including proliferative rate, an extensive replicative potential, the potential to generate different cell types of a given tissue, and an ability to independently migrate to a damaged area. This is also evidenced by the common molecular principles regulating key processes associated with cell division and apoptosis. Autosomal recessive primary microcephaly (MCPH) is a neurogenic mitotic disorder that is characterized by decreased brain size and mental retardation. Until now, a total of 25 genes have been identified that are known to be associated with MCPH. The inactivation (yin) of most MCPH genes leads to neurogenesis defects, while the upregulation (yang) of some MCPH genes is associated with different kinds of carcinogenesis. Here, we try to summarize the roles of MCPH genes in these two diseases and explore the underlying mechanisms, which will help us to explore new, attractive approaches to targeting tumor cells that are resistant to the current therapies.

SAG expression associates with COPB2-related signaling and a poorer prognosis in breast cancer

SAG is an essential RING component of the Cullin-RING ligase (CRL) E3 ubiquitin ligase complex, which regulates diverse signaling pathways and biological processes, including cell apoptosis, embryonic development, angiogenesis, and tumorigenesis. In the present study, we revealed that SAG gene expression is upregulated in breast cancer cells and that SAG overexpression is associated with significant poorer survival in breast cancer, especially the luminal A subtype. We also detected highly correlated co-overexpression of SAG and COPB2 in breast cancers. Subsequent in vitro experiments demonstrated that SAG and COPB2 act cooperatively to stimulate breast cancer cell proliferation, migration and invasion. Our findings suggest that levels of SAG and COPB2 expression may be useful prognostic indicators in breast cancers and that SAG may be involved in COPB2-related signaling during breast cancer development.

Targeting Non-Oncogene Addiction: Focus on Thyroid Cancer

Thyroid carcinoma (TC) is the most common malignancy of endocrine organs with an increasing incidence in industrialized countries. The majority of TC are characterized by a good prognosis, even though cases with aggressive forms not cured by standard therapies are also present. Moreover, target therapies have led to low rates of partial response and prompted the emergence of resistance, indicating that new therapies are needed. In this review, we summarize current literature about the non-oncogene addiction (NOA) concept, which indicates that cancer cells, at variance with normal cells, rely on the activity of genes, usually not mutated or aberrantly expressed, essential for coping with the transformed phenotype. We highlight the potential of non-oncogenes as a point of intervention for cancer therapy in general, and present evidence for new putative non-oncogenes that are essential for TC survival and that may constitute attractive new therapeutic targets.

High expression of COPB2 predicts adverse outcomes: A potential therapeutic target for glioma

Aims

To evaluate the clinical significance of coatomer protein complex subunit beta 2 (COPB2) in patients with glioma using a bioinformatics analysis.

Methods

Oncomine, GEO, and The Cancer Genome Atlas databases were used to examine the COPB2 transcript levels in glioma tissues. Gene expression profiles with clinical information from low‐grade glioma and glioblastoma (GBM) projects were analyzed for associations between COPB2 expression and clinicopathologic characteristics. Kaplan‐Meier survival and Cox regression analyses were used for survival analysis. Gene set enrichment analysis (GSEA) was conducted to screen the pathways involved in COPB2 expression. Gene set variation analysis (GSVA) and correlograms were performed to verify the correlations between COPB2 and inflammatory responses. Canonical correlation analyses examined whether COPB2‐high patients have more infiltrating inflammatory and immune cells.

Results

COPB2 was highly expressed in gliomas and high COPB2 expression correlated with shorter overall survival time and several poor clinical prognostic variables. GSEA indicated that some immune‐related pathways and other signaling pathways in cancer were associated with the COPB2‐high phenotype. The GSVA and canonical correlation analysis demonstrated that COPB2 expression was closely linked to inflammatory and immune responses, and higher immune cell infiltration.

Conclusions

COPB2 may be a potential prognostic biomarker and an immunotherapeutic target for glioma.