PAQR4 has a tumorigenic effect in human breast cancers in association with reduced CDK4 degradation

PAQR4: From spatial regulation of cell signaling to physiological homeostasis and diseases

Progestin and adipoQ receptor family member 4 (PAQR4) gene is a recently discovered seven-transmembrane protein-coding gene that belongs to the PAQR family. An increasing amount of evidence suggests that PAQR4 is upregulated in multiple tumors and participates in tumor progression and chemotherapy resistance via different signaling pathways; PAQR4 regulates cellular ceramide homeostasis by influencing sphingolipid metabolism and glycerol metabolism, and plays a significant role in adipose tissue remodeling. Meanwhile, it is known that the differential expression of PAQR4 is associated with the occurrence of various diseases and is a potential biomarker and therapeutic target. This article conducts a systematic review of the subcellular localization of PAQR4, its topological structure characteristics, and its functions in cancer occurrence, metabolic diseases, and fertility, and provides clues for the future research and translational application of PAQR4.

Autophagic degradation of CDK4 is responsible for G0/G1 cell cycle arrest in NVP-BEZ235-treated neuroblastoma

BACKGROUND

CDK4 is highly expressed and associated with poor prognosis and decreased survival in advanced neuroblastoma (NB). Targeting CDK4 degradation presents a potentially promising therapeutic strategy compared to conventional CDK4 inhibitors. However, the autophagic degradation of the CDK4 protein and its anti-proliferation effect in NB cells has not been mentioned.

RESULTS

We identified autophagy as a new pathway for the degradation of CDK4. Firstly, autophagic degradation of CDK4 is critical for NVP-BEZ235-induced G0/G1 arrest, as demonstrated by the overexpression of CDK4, autophagy inhibition, and blockade of autophagy-related genes. Secondly, we present the first evidence that p62 binds to CDK4 and then enters the autophagy-lysosome to degrade CDK4 in a CTSB-dependent manner in NVP-BEZ235 treated NB cells. Similar results regarding the interaction between p62 and CDK4 were observed in the NVP-BEZ235 treated NB xenograft mouse model.

CONCLUSIONS

Autophagic degradation of CDK4 plays a pivotal role in G0/G1 cell cycle arrest in NB cells treated with NVP-BEZ235.

PGRMC1 and PAQR4 are promising molecular targets for a rare subtype of ovarian cancer

The heterogeneity of ovarian cancer (OC) has made developing effective treatments difficult. Nowadays, hormone therapy plays a growing role in the treatment of OC; however, hormone modulators have had only limited success so far. To provide a more rigorous foundation for hormonal therapy for different OC subtypes, the current study used a series of bioinformatics approaches to analyse the expression profiles of genes encoding membrane progesterone (PGRMC1, progestins and the adipoQ receptor [PAQR] family), and androgen (zinc transporter member 9 [ZIP9], OXER1) receptors. Our work investigated also their prognostic value in the context of OC. We found differences in expression of ZIP9 and OXER1 between different OC subtypes, as well as between patient tumour and normal tissues. Expression of mRNA encoding PAQR7 and PAQR8 in a panel of OC cell lines was below the qPCR detection limit and was downregulated in tumour tissue samples, whereas high expression of PGRMC1 and PAQR4 mRNA was observed in rare subtypes of OC cell lines. In addition, chemical inhibition of PGRMC1 reduced the viability of rare OCs represented by COV434 cells. In conclusion, PGRMC1 and PAQR4 are promising targets for anticancer therapy, particularly for rare subtypes of OC. These findings may reflect differences in the observed responses of various OC subtypes to hormone therapy.

PAQR4 regulates adipocyte function and systemic metabolic health by mediating ceramide levels

PAQR4 is an orphan receptor in the PAQR family with an unknown function in metabolism. Here, we identify a critical role of PAQR4 in maintaining adipose tissue function and whole-body metabolic health. We demonstrate that expression of Paqr4 specifically in adipocytes, in an inducible and reversible fashion, leads to partial lipodystrophy, hyperglycaemia and hyperinsulinaemia, which is ameliorated by wild-type adipose tissue transplants or leptin treatment. By contrast, deletion of Paqr4 in adipocytes improves healthy adipose remodelling and glucose homoeostasis in diet-induced obesity. Mechanistically, PAQR4 regulates ceramide levels by mediating the stability of ceramide synthases (CERS2 and CERS5) and, thus, their activities. Overactivation of the PQAR4-CERS axis causes ceramide accumulation and impairs adipose tissue function through suppressing adipogenesis and triggering adipocyte de-differentiation. Blocking de novo ceramide biosynthesis rescues PAQR4-induced metabolic defects. Collectively, our findings suggest a critical function of PAQR4 in regulating cellular ceramide homoeostasis and targeting PAQR4 offers an approach for the treatment of metabolic disorders.

PAQR4 oncogene: a novel target for cancer therapy

Despite decades of basic and clinical research and trials of promising new therapies, cancer remains a major cause of morbidity and mortality due to the emergence of drug resistance to anticancer drugs. These resistance events have a very well-understood underlying mechanism, and their therapeutic relevance has long been recognized. Thus, drug resistance continues to be a major obstacle to providing cancer patients with the intended "cure". PAQR4 (Progestin and AdipoQ Receptor Family Member 4) gene is a recently identified novel protein-coding gene associated with various human cancers and acts through different signaling pathways. PAQR4 has a significant influence on multiple proteins that may regulate various gene expressions and may develop chemoresistance. This review discusses the roles of PAQR4 in tumor immunity, carcinogenesis, and chemoresistance. This paper is the first review, discussing PAQR4 in the pathogenesis of cancer. The review further explores the PAQR4 as a potential target in various malignancies.

A novel transcriptomic signature associated with lymphovascular invasion predicts clinical outcomes, tumor microenvironment, and therapeutic response in lung adenocarcinoma

PURPOSE

Since TNM staging has limitations for predicting post-operative outcomes and relapse, more effective prediction tools need to be researched and developed. Lymphovascular invasion, LVI, as a histopathological feature, has been widely shown to have a correlation with poor prognosis and early recurrence of lung adenocarcinoma (LUAD). However, LVI assessment is limited by subjective bias, and therefore its efficacy in practical clinical application needs further clarification. The aim of this study was to formulate a new signature based on LVI-related genes to predict prognosis and recurrence in patients with lung adenocarcinoma.

METHODS

Clinicopathological information, gene sequencing data and whole slide images (WSIs) of LUAD patients were downloaded from the Cancer Genome Atlas (TCGA) databases. LVI statue were evaluated by professional pathologists, and then the differentially expressed genes (LVI DEGs) associated with LVI were screened. The least absolute shrinkage and selection operator (LASSO) and Step Cox regression models were used to construct LVI-associated risk scores (LVRS), including PAQR4, ARGHEF6, CKS1B, CFTR and SEC14L4. The validity of the LVRS score was evaluated on multiple external datasets and our JSSZL cohort dataset. Using LVRS scores and clinical information, nomogram were constructed for use by clinicians. In addition, we further explored the relationship between LVRS score and clinicopathological features, immune infiltration, tumor mutational load, and immunotherapy response, and confirmed the expression of key genes in LVRS score in lung adenocarcinoma tissues using qRT-PCR and immunohistochemistry (IHC) techniques.

RESULTS

Based on the LVRS, patients could be classified into high-LVRS and low-LVRS groups. It was found that OS and PFS were significantly worse in the high-LVRS group than in the low-LVRS group (p < 0.001). By ROC curve analysis, it could be found that the nomogram combining LVRS and clinical information could accurately predict the prognosis of LUAD patients with the area under the curve of 1,3,5-year survival rate could reach 0.754, 0.741 and 0.735. The results of univariate and multivariate analysis showed that LVRS was an independent prognostic factor. At the same time, there were significant differences in the mutation profiles and immune microenvironment between the high-LVRS and low-LVRS groups, with the high-LVRS group having a significantly higher mutation rate than the low-LVRS group and exhibiting immunological "cold" features. By the experimental results, higher expression levels of PAQR4 and CKS1B were found in LUAD tissues, while lower expression levels of ARGHEF6, CFTR and SEC14L4 were observed.

CONCLUSIONS

The LVRS established in this study serves as a valid tool to predict the prognosis and recurrence status of lung adenocarcinoma patients and has a predictive effect on the response to postoperative treatment. The establishment of LVRS may offer some theoretical support to clinical treatment strategies for patients with lung adenocarcinoma following surgical intervention.

Pan-cancer analysis of the prognostic and immunological role of PAQR4

Progestin and adipoQ receptor family member 4 (PAQR4) is a protein-coding gene. Recent studies have shown that PAQR4 is related to the development of multiple cancers. However, there is no systematic pan-cancer analysis of this gene. In this study, the expression of PAQR4, correlations with clinical prognosis, immune situation, and its potential molecular functions and mechanisms in pan-cancer were explored by bioinformatics analysis. The Cancer Genome Atlas was applied to investigate the relations between PAQR4 and clinical features, prognostic effects, and tumor immune microenvironment. R software was used to perform statistical analysis and figure creation. The expression of PAQR4 in BLCA and KIRC was validated by qRT-PCR and immunohistochemistry, and its function was explored by cellular experiments. Bioinformatics analysis revealed that PAQR4 was up-regulated in multiple cancers and related to poor prognosis. The high expression of PAQR4 was closely associated with high tumor stage, immune cell infiltration, tumor mutation burden, and microsatellite instability in different cancer types. In addition, the high expression of PAQR4 also indicated involvement in the immune regulatory pathways. The involvement of PAQR4 in the immune regulation of different tumors was confirmed by GSEA enrichment analysis. Moreover, PAQR4 was highly expressed in bladder cancer and renal clear cell carcinoma tissues and cell lines. Cell proliferation, migration, and invasion of bladder cancer and renal clear cell carcinoma cell lines were significantly decreased after the knockdown of PAQR4. This study elucidated the role of PAQR4 in carcinogenesis as well as tumor immunity. PAQR4 may serve as a potential prognostic biomarker in a variety of cancers.

Golgi scaffold protein PAQR3 as a candidate suppressor of gastric cardia adenocarcinoma via regulating TGF ‐β/Smad pathway

Objectives

To investigate the function of PAQR3 in gastric cardia adenocarcinoma (GCA) and understand the possible mechanism of PAQR3 in regulating epithelial–mesenchymal transition (EMT).

Methods

We detected PAQR3 protein in 146 GCA tissues and paired normal adjacent tissues (PNTs) specimens using immunohistochemical analysis, and explored its clinical significance. The expression levels of PAQR3 protein in 20 GCA tissues, their paired PNTs, HGC27, SGC7901, and GES‐1 cells were analyzed by Western blot. Wild‐type PAQR3 was overexpressed in HGC27 cells. The effects of PAQR3 overexpression on the function of HGC27 cells and its underlying mechanisms were then analyzed through a series of cell and molecular biology experiments.

Results

PAQR3 was significantly down‐regulated in GCA tissues when compared with paired PNTs (p < 0.0001). The expression level of PAQR3 in GCA tissues was significantly negatively correlated with Helicobacter pylori infection (p = 0.000), venous invasion (p = 0.000), invasion depth (p = 0.000), lymph node metastasis (p = 0.022), tumor stage (p = 0.000), and patient survival (p = 0.009). Downregulation of PAQR3 was highly correlated with increased EMT signature and activated TGF‐β/Smad pathway in GCA tissues. Overexpression of PAQR3 in HGC27 cells negatively regulates its cellular functions, such as cell proliferation and migration, and suppresses EMT. Mechanistically, overexpression of PAQR3 significantly down‐regulates the protein expression levels of TGF‐1, p‐Smad2, and p‐Smad3 in HGC27 cells.

Conclusion

PAQR3 was significantly down‐regulated in GCA tissues, HGC27, and SGC7901 cells. PAQR3 significantly inhibits the proliferation, migration, and invasion of HGC27 cells. Mechanistically, PAQR3 can inhibit the EMT process in HGC27 cells by regulating TGF‐β/Smad signaling pathway.

LINC00162 regulates cell proliferation and apoptosis by sponging PAQR4-targeting miR-485-5p

Growing evidence indicates that long intergenic noncoding RNAs play an important role in cancer progression by affecting gene regulation at the transcriptional and posttranscriptional levels. Recent studies have shown that long intergenic noncoding RNA functions as a competitive endogenous RNA, which can interact with and mitigate the function of microRNA. In this study, we investigated the molecular mechanism by which LINC00162 regulates cell proliferation and apoptotic cell death. By analyzing RNA sequencing data, LINC00162 was identified to be a target of heterogeneous nuclear ribonucleoprotein K (hnRNPK). HnRNPK positively regulated LINC00162 expression through p38 mitogen-activated protein kinase. Lowering the level of either hnRNPK or LINC00162 decreased proliferation and colony formation while it increased apoptotic cell death. Small RNA sequencing followed by the antisense oligonucleotide pulldown, revealed that LINC00162 interacts directly with miR-485-5p which exhibited tumor-suppressing effects by suppressing cell proliferation and colony formation, and increasing apoptotic cell death. Through the bioinformatic approaches, progestin and adipoQ receptor 4 (PAQR4) was selected as a common target of LINC00162 and miR-485-5p. miR-485-5p decreased the expression of PAQR4 by directly binding to the 3'-untranslated region of PAQR4 messenger RNA. Knockdown of hnRNPK and LINC00162 increased the level of functional miR-485-5p, indicating that LINC00162 may compete for miR-485-5p, thereby derepressing PAQR4 expression. Overexpression of either hnRNPK or LINC00162, or inhibition of miR-485-5p, protected cells against etoposide-induced apoptotic death. Our findings demonstrate that a regulatory paradigm implicating hnRNPK, LINC00162, miR-485-5p, and PAQR4 plays an important role in cell proliferation and apoptosis, and is a promising target for cancer therapeutics.

Overexpressed PAQR4 predicts poor overall survival and construction of a prognostic nomogram based on PAQR family for hepatocellular carcinoma

OBJECTIVE

We aimed to explore the expression and clinical prognostic significance of PAQR4 in hepatocellular carcinoma (HCC).

METHODS

We obtained the gene expression matrix and clinical data of HCC from the cancer genome atlas (TCGA) and international cancer genome consortium (ICGC) databases. The prognostic value of PAQR4 in HCC was evaluated using the Kaplan-Meier and Cox regression analyses. PAQR4-related pathways were explored by gene set enrichment analysis (GSEA). A clinical nomogram prognostic model based on the PAQR family was constructed using Cox proportional hazards models.

RESULTS

We found that PAQR4 is overexpressed in HCC from multiple databases; additionally, quantitative real-time polymerase chain reaction (qRT-PCR) validated the upregulation of PAQR4 in HCC. PAQR4 expression was related to age, grade, alpha fetoprotein (AFP), T classification and clinical stage of HCC patients. High PAQR4 expression was associated with poor overall survival and was an independent prognostic factor for HCC patients through Kaplan-Meier analysis and Cox regression analysis, respectively. In addition, GSEA identified that the high PAQR4 expression phenotype was involved in the cell cycle, Notch signaling pathway, mTOR signaling pathway, etc. Finally, three PAQR family genes (PAQR4, PAQR8 and PAQR9) were associated with the prognosis of patients with HCC. A clinical nomogram prediction model was verified in TCGA training and ICGC validation sets, and it exerted dramatic predictive efficiency in this study.

CONCLUSIONS

PAQR4 may be regarded as a promising prognostic biomarker and therapeutic target for HCC.

PAQR4 promotes the development of hepatocellular carcinoma by activating PI3K/AKT pathway

Progestin and adipoQ receptor 4 (PAQR4) is a novel tumorigenic factor that promotes cell proliferation and metastasis in lung and breast cancer, but its role in hepatocellular carcinoma (HCC) is unknown. The aim of our study was to explore its role and underlying mechanism in the development of HCC. Analysis of GEPIA database indicated that PAQR4 was highly expressed in HCC samples, and the mRNA level of PAQR4 was negatively correlated with the overall survival of HCC patients. Knockdown of PAQR4 in Hep3B cells suppressed cell proliferation by hindering G1/S transition of cell cycle as shown by the flow cytometry analysis. PAQR4 knockdown also expedited the cell apoptosis. Knockdown of PAQR4 repressed the migratory and invasive potential of Hep3B cells. PAQR4 knockdown sensitized Hep3B cells to apatinib-based chemotherapy. PAQR4 knockdown blocked the activation of PI3K/AKT pathway, as reflected by the reduced phosphorylation of AKT and p85. Conversely, overexpression of PAQR4 exerted opposite effects in Huh-7 cells. PI3K inhibitor LY294002 could eliminate the effects of PAQR4 on cell proliferation, apoptosis, chemoresistance, and invasion. In tumor xenograft model, knockdown of PAQR4 suppressed tumor growth in vivo, while PAQR4 overexpression promoted tumor growth. Collectively, our data suggest that PAQR4 has a tumorigenic effect on HCC progression by activating PI3K/AKT pathway.

Computational Approaches for Cancer-Fighting: From Gene Expression to Functional Foods

It is today widely accepted that a healthy diet is very useful to prevent the risk for cancer or its deleterious effects. Nutrigenomics studies are therefore taking place with the aim to test the effects of nutrients at molecular level and contribute to the search for anti-cancer treatments. These efforts are expanding the precious source of information necessary for the selection of natural compounds useful for the design of novel drugs or functional foods. Here we present a computational study to select new candidate compounds that could play a role in cancer prevention and care. Starting from a dataset of genes that are co-expressed in programmed cell death experiments, we investigated on nutrigenomics treatments inducing apoptosis, and searched for compounds that determine the same expression pattern. Subsequently, we selected cancer types where the genes showed an opposite expression pattern and we confirmed that the apoptotic/nutrigenomics expression trend had a significant positive survival in cancer-affected patients. Furthermore, we considered the functional interactors of the genes as defined by public protein-protein interaction data, and inferred on their involvement in cancers and/or in programmed cell death. We identified 7 genes and, from available nutrigenomics experiments, 6 compounds effective on their expression. These 6 compounds were exploited to identify, by ligand-based virtual screening, additional molecules with similar structure. We checked for ADME criteria and selected 23 natural compounds representing suitable candidates for further testing their efficacy in apoptosis induction. Due to their presence in natural resources, novel drugs and/or the design of functional foods are conceivable from the presented results.

A novel receptor for platelet-activating factor and lysophosphatidylcholine in Trypanosoma cruzi

The lipid mediators, platelet-activating factor (PAF) and lysophosphatidylcholine (LPC), play relevant pathophysiological roles in Trypanosoma cruzi infection. Several species of LPC, including C18:1 LPC, which mimics the effects of PAF, are synthesized by T. cruzi. The present study identified a receptor in T. cruzi, which was predicted to bind to PAF, and found it to be homologous to members of the progestin and adiponectin family of receptors (PAQRs). We constructed a three-dimensional model of the T. cruzi PAQR (TcPAQR) and performed molecular docking to predict the interactions of the TcPAQR model with C16:0 PAF and C18:1 LPC. We knocked out T. cruzi PAQR (TcPAQR) gene and confirmed the identity of the expressed protein through immunoblotting and immunofluorescence assays using an anti-human PAQR antibody. Wild-type and knockout (KO) parasites were also used to investigate the in vitro cell differentiation and interactions with peritoneal mouse macrophages; TcPAQR KO parasites were unable to react to C16:0 PAF or C18:1 LPC. Our data are highly suggestive that PAF and LPC act through TcPAQR in T. cruzi, triggering its cellular differentiation and ability to infect macrophages.

Expression and Clinical Significance of CREPT and CDK4 in Cervical Cancer

The article's abstract is not available.  

Circular RNA CircNOLC1, Upregulated by NF-KappaB, Promotes the Progression of Prostate Cancer via miR-647/PAQR4 Axis

Background

CircRNAs recently have shown critical roles in tumor biology. However, their roles in prostate cancer (PCa) remains largely unclear.

Methods

CircRNA microarrays were performed in immortal prostate cell line RWPE1 and PCa cell lines as DU145, PC3, LNCaP, C4-2, and 22RV1. Combined with upregulated circRNAs in PCa tissues, circNOLC1 expression was validated in PCa cells and tissues via qRT-PCR and FISH. Sanger sequencing, actinomycin D, gDNA, and cDNA, RNase R assays were used to assess the circular characteristics of circNOLC1. CCK-8, colony formation, transwell migration assays, and mice xenograft models were conducted to evaluate the functions of PCa cells after circNOLC1 knockdown and overexpression. RNA pulldown, luciferase reporter assay, FISH (fluorescence in situ hybridization), and CHIP were utilized to illustrate the further mechanisms of circNOLC1.

Results

Our research indicated that circNOLC1 was overexpressed in PCa cells and tissues, and circNOLC1 was more stable than linear NOLC1 mRNA. CircNOLC1 promoted PCa cells proliferation and migration in vitro and vivo. Additionally, we found that circNOLC1 could upregulate PAQR4 expression by sponging miR-647, leading to the activation of PI3K/Akt pathway. Moreover, NF-kappaB was identified to bind to the NOLC1 promoter sites and upregulated both NOLC1 and circNOLC1 expression.

Conclusion

CircNOLC1, elevated by transcription factor NF-kappaB, promotes PCa progression via a miR-647/PAQR4 axis, and circNOLC1 is a potential biomarker and target for PCa treatment.

A novel seven-gene signature as Prognostic Biomarker in Hepatocellular Carcinoma

Purpose: Our study is designed to develop and certify a promising prognostic signature for hepatocellular carcinoma (HCC).

Materials and methods: We retrospectively analyzed mRNA expression profiles and clinicopathological data fetched from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. We formulated a prognostic seven-gene signature composed of differentially expressed mRNAs (DEmRNAs) between HCC and nonneoplastic tissues through univariate Cox regression analysis. The receiver operating characteristic (ROC) curve, survival analysis and multivariate Cox regression analysis as well as nomograms were utilized to assess the prognostic performance of the seven-gene signature.

Results: The risk score based on a seven-gene signature categorized HCC subjects into a high- and low-risk group. There was significantly discrepant overall survival (OS) between patients in both groups and the corresponding ROC curve revealed a satisfactory predictive performance in HCC survival in both TCGA and GSE76427 cohort. Multivariate Cox regression analysis demonstrated that a seven-gene signature was an independently prognostic factor for HCC. Nomograms combining this prognostic signature with significant clinical characteristics conferred a crucial reference to predict the 1-,3- and 5 years OS.

Conclusions: Our study defined a promising seven-gene signature and nomogram model to forecast the OS of HCC patients, which is instrumental in clinical decision and personalized therapy.

Adaptive changes in the genomes of wild rabbits after 16 years of viral epidemics

Since its introduction to control overabundant invasive European rabbits (Oryctolagus cuniculus), the highly virulent rabbit haemorrhagic disease virus (RHDV) has caused regular annual disease outbreaks in Australian rabbit populations. Although initially reducing rabbit abundance by 60%, continent-wide, experimental evidence has since indicated increased genetic resistance in wild rabbits that have experienced RHDV-driven selection. To identify genetic adaptations, which explain the increased resistance to this biocontrol virus, we investigated genome-wide SNP (single nucleotide polymorphism) allele frequency changes in a South Australian rabbit population that was sampled in 1996 (pre-RHD genomes) and after 16 years of RHDV outbreaks. We identified several SNPs with changed allele frequencies within or close to genes potentially important for increased RHD resistance. The identified genes are known to be involved in virus infections and immune reactions or had previously been identified as being differentially expressed in healthy versus acutely RHDV-infected rabbits. Furthermore, we show in a simulation study that the allele/genotype frequency changes cannot be explained by drift alone and that several candidate genes had also been identified as being associated with surviving RHD in a different Australian rabbit population. Our unique data set allowed us to identify candidate genes for RHDV resistance that have evolved under natural conditions, and over a time span that would not have been feasible in an experimental setting. Moreover, it provides a rare example of host genetic adaptations to virus-driven selection in response to a suddenly emerging infectious disease.

Breviscapine suppresses the growth and metastasis of prostate cancer through regulating PAQR4-mediated PI3K/Akt pathway

OBJECTIVES

Prostate cancer, one of the most frequently diagnosed tumors of men, leads to poor quality of life. Previous studies have shown that breviscapine (BRE) exerts therapeutic activity in malignant tumors. However, the role and mechanism of BRE exhibit an anti-tumor effect on prostate cancer are largely unknown.

METHODS

The mRNA and protein levels in prostate cancer tissues and cell lines were measured using RT-qPCR, western blot, and immunohistochemical staining, respectively. Cell proliferation, invasion, and migration in both PC3 and DU145 cells were evaluated using CCK-8 and Transwell assay. The effect of BRE on cell proliferation and metastasis by regulating the PAQR4-mediated PI3K/Akt pathway in vitro and in vivo was determined.

RESULTS

PAQR4 was significantly overexpressed in prostate cancer tissues and cell lines, which was positively correlated with poor prognosis. Knockdown of PAQR4 inhibited the proliferation, invasion, migration, and epithelial-mesenchymal transition (EMT) of both PC3 and DU145 cells. Mechanistically, BRE treatment significantly suppressed the malignant biological behavior of both prostate cancer cells by downregulating PAQR4 and blocking the PI3K/Akt pathway. In vivo experiments, BRE administration remarkably inhibited tumor growth and metastasis in a xenograft model of prostate cancer.

CONCLUSION

Our findings revealed that BRE exerts anti-tumor and anti-metastasis roles in prostate cancer by inhibiting PAQR4-mediated PI3K/Akt pathway, which provides a new therapeutic agent for prostate cancer clinical treatment.

Golgi-Localized PAQR4 Mediates Antiapoptotic Ceramidase Activity in Breast Cancer

The metabolic network of sphingolipids plays important roles in cancer biology. Prominent sphingolipids include ceramides and sphingosine-1-phosphate that regulate multiple aspects of growth, apoptosis, and cellular signaling. Although a significant number of enzymatic regulators of the sphingolipid pathway have been described in detail, many remained poorly characterized. Here we applied a patient-derived systemic approach to identify and molecularly define progestin and adipoQ receptor family member IV (PAQR4) as a Golgi-localized ceramidase. PAQR4 was approximately 5-fold upregulated in breast cancer compared with matched control tissue and its overexpression correlated with disease-specific survival rates in breast cancer. Induction of PAQR4 in breast tumors was found to be subtype-independent and correlated with increased ceramidase activity. These findings establish PAQR4 as Golgi-localized ceramidase required for cellular growth in breast cancer. SIGNIFICANCE: Induction of and cellular dependency on de novo sphingolipid synthesis via PAQR4 highlights a central vulnerability in breast cancer that may serve as a viable therapeutic target.

PAQR4 promotes chemoresistance in non-small cell lung cancer through inhibiting Nrf2 protein degradation

Purpose: Lung cancer is the leading cause of cancer related deaths worldwide. We have previously identified many differentially expressed genes (DEGs) from large scale pan-cancer dataset using the Cross-Value Association Analysis (CVAA) method. Here we focus on Progestin and AdipoQ Receptor 4 (PAQR4), a member of the progestin and adipoQ receptor (PAQR) family localized in the Golgi apparatus, to determine their clinical role and mechanism in the development of non-small cell lung cancer (NSCLC). Methods: The protein expression profile of PAQR4 was examined by IHC using tissue microarrays, and the effects of PAQR4 on cell proliferation, colony formation and xenograft tumor formation were tested in NSCLC cells. Real-time RT-PCR, co-immunoprecipitation (co-IP) and GST-pulldown assays were used to explore the mechanism of action of PAQR4. Results: We provided evidence showing that PAQR4 is increased in NSCLC cancer cell lines (A549, H1299, H1650, H1975, H358, GLC-82 and SPC-A1), and identified many mutations in PAQR4 in non-small cell lung cancer (NSCLC) tissues. We demonstrated that PAQR4 high expression correlates with a worse clinical outcome, and that its knockdown suppresses cell proliferation by inducing apoptosis. Importantly, overexpressed PAQR4 physically interacts with Nrf2 in NSCLC cells, blocking the interaction between Nrf2 and Keap1. Conclusion: Our results suggest that PAQR4 depletion enhances the sensitivity of cancerous cell to chemotherapy both in vitro and xenograft tumor formation in vivo, by promoting Nrf2 protein degradation through a Keap1-mediated ubiquitination process.

PAQR9 Modulates BAG6-mediated protein quality control of mislocalized membrane proteins

Protein quality control is crucial for maintaining cellular homeostasis and its dysfunction is closely linked to human diseases. The post-translational protein quality control machinery mainly composed of BCL-2-associated athanogene 6 (BAG6) is responsible for triage of mislocalized membrane proteins (MLPs). However, it is unknown how the BAG6-mediated degradation of MLPs is regulated. We report here that PAQR9, a member of the Progesterone and AdipoQ receptor (PAQR) family, is able to modulate BAG6-mediated triage of MLPs. Analysis with mass spectrometry identified that BAG6 is one of the major proteins interacting with PAQR9 and such interaction is confirmed by co-immunoprecipitation and co-localization assays. The protein degradation rate of representative MLPs is accelerated by PAQR9 knockdown. Consistently, the polyubiquitination of MLPs is enhanced by PAQR9 knockdown. PAQR9 binds to the DUF3538 domain within the proline-rich stretch of BAG6. PAQR9 reduces the binding of MLPs to BAG6 in a DUF3538 domain-dependent manner. Taken together, our results indicate that PAQR9 plays a role in the regulation of protein quality control of MLPs via affecting the interaction of BAG6 with membrane proteins.

PAQR4 promotes cell proliferation and metastasis through the CDK4-pRB-E2F1 pathway in non-small-cell lung cancer

Background

It is reported that progestin and adipoQ receptor 4 (PAQR4) has a tumorigenic effect on human breast cancer, but the role of PAQR4 in non-small-cell lung cancer (NSCLC) is unknown. The aim of this study was to investigate the role of PAQR4 in NSCLC.

Methods

Quantitative real-time PCR (qRT-PCR) and immunohistchemical (IHC) staining were used to analyze the expression of PAQR4 in HCC tissues and adjacent normal tissues. MTT, colony formation assay, flow cytometry (FCM), wound healing assays and transwell invasion assays were used to investigate the effects of PAQR4 on cell proliferation, colony formation, cell cycle, migration and invasion. Murine xenograft model assay was carried out to characterize the effects of PAQR4 knockdown on tumor growth in vivo.

Results

In this study, we found that the expression of PAQR4 was significantly upregulated in the NSCLC tissues of patients compared with that in the matched non-cancerous tissues. In addition, we found that PAQR4 was also significantly up-regulated in the NSCLC cell lines compared with normal human lung epithelial cells. Besides, we found that the over-expression of PAQR4 promoted promoted proliferation, colony formation, migration and invasion of the NSCLC cells, whereas the knockdown of PAQR4 inhibited proliferation, colony formation, migration and invasion of the NSCLC cells. Furthermore, mechanistic studies showed that the CDK4-pRB-E2F1 pathway was involved in NSCLC.

Conclusion

Hence, these results suggest that PAQR4 may be used as a new target in NSCLC therapy.