Enhanced expression of IMPDH2 promotes metastasis and advanced tumor progression in patients with prostate cancer

IMPDH2 suppression impedes cell proliferation by instigating cell cycle arrest and stimulates apoptosis in pediatric hepatoblastoma

BACKGROUND

Hepatoblastoma (HB) is the most common pediatric liver tumor, presenting significant therapeutic challenges due to its high rates of recurrence and metastasis. While Inosine Monophosphate Dehydrogenase 2(IMPDH2) has been associated with cancer progression, its specific role and clinical implications in HB have not been fully elucidated.

METHODS

This study utilized Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and Tissue Microarray (TMA) for validation. Following this, IMPDH2 was suppressed, and a series of in vitro assays were conducted. Flow cytometry was employed to assess apoptosis and cell cycle arrest. Additionally, the study explored the synergistic therapeutic effects of mycophenolate mofetil (MMF) and doxorubicin (DOX) on HB cell lines.

RESULTS

The study identified a marked overexpression of IMPDH2 in HB tissues, which was strongly correlated with reduced Overall Survival (OS) and Event-Free Survival (EFS). IMPDH2 upregulation was also found to be associated with key clinical-pathological features, including pre-chemotherapy alpha-fetoprotein (AFP) levels, presence of preoperative metastasis, and the pre-treatment extent of tumor (PRETEXT) staging system. Knockdown of IMPDH2 significantly inhibited HB cell proliferation and tumorigenicity, inducing cell cycle arrest at the G0/G1 phase. Notably, the combination of MMF, identified as a specific IMPDH2 inhibitor, with DOX, substantially enhanced the therapeutic response.

CONCLUSION

The overexpression of IMPDH2 was closely linked to adverse outcomes in HB patients and appeared to accelerate cell cycle progression. These findings suggest that IMPDH2 may serve as a valuable prognostic indicator and a potential therapeutic target for HB.

IMPACT

The present study unveiled a significant overexpression of inosine monophosphate dehydrogenase 2 (IMPDH2) in hepatoblastoma (HB) tissues, particularly in association with metastasis and recurrence of the disease. The pronounced upregulation of IMPDH2 was found to be intimately correlated with adverse outcomes in HB patients. This overexpression appears to accelerate the progression of the cell cycle, suggesting that IMPDH2 may serve as a promising candidate for both a prognostic marker and a therapeutic target in the context of HB.

Growth Transformation of B Cells by Epstein-Barr Virus Requires IMPDH2 Induction and Nucleolar Hypertrophy

The in vitro growth transformation of primary B cells by Epstein-Barr virus (EBV) is the initial step in the development of posttransplant lymphoproliferative disorder (PTLD). We performed electron microscopic analysis and immunostaining of primary B cells infected with wild-type EBV. Interestingly, the nucleolar size was increased by two days after infection. A recent study found that nucleolar hypertrophy, which is caused by the induction of the IMPDH2 gene, is required for the efficient promotion of growth in cancers. In the present study, RNA-seq revealed that the IMPDH2 gene was significantly induced by EBV and that its level peaked at day 2. Even without EBV infection, the activation of primary B cells by the CD40 ligand and interleukin-4 increased IMPDH2 expression and nucleolar hypertrophy. Using EBNA2 or LMP1 knockout viruses, we found that EBNA2 and MYC, but not LMP1, induced the IMPDH2 gene during primary infections. IMPDH2 inhibition by mycophenolic acid (MPA) blocked the growth transformation of primary B cells by EBV, leading to smaller nucleoli, nuclei, and cells. Mycophenolate mofetil (MMF), which is a prodrug of MPA that is approved for use as an immunosuppressant, was tested in a mouse xenograft model. Oral MMF significantly improved the survival of mice and reduced splenomegaly. Taken together, these results indicate that EBV induces IMPDH2 expression through EBNA2-dependent and MYC-dependent mechanisms, leading to the hypertrophy of the nucleoli, nuclei, and cells as well as efficient cell proliferation. Our results provide basic evidence that IMPDH2 induction and nucleolar enlargement are crucial for B cell transformation by EBV. In addition, the use of MMF suppresses PTLD. IMPORTANCE EBV infections cause nucleolar enlargement via the induction of IMPDH2, which are essential for B cell growth transformation by EBV. Although the significance of IMPDH2 induction and nuclear hypertrophy in the tumorigenesis of glioblastoma has been reported, EBV infection brings about the change quickly by using its transcriptional cofactor, EBNA2, and MYC. Moreover, we present here, for the novel, basic evidence that an IMPDH2 inhibitor, namely, MPA or MMF, can be used for EBV-positive posttransplant lymphoproliferative disorder (PTLD).

Causal Gene Identification Using Non-Linear Regression-Based Independence Tests

With the development of biomedical techniques in the past decades, causal gene identification has become one of the most promising applications in human genome-based business, which can help doctors to evaluate the risk of certain genetic diseases and provide further treatment recommendations for potential patients. When no controlled experiments can be applied, machine learning techniques like causal inference-based methods are generally used to identify causal genes. Unfortunately, most of the existing methods detect disease-related genes by ranking-based strategies or feature selection techniques, which generally return a superset of the corresponding real causal genes. There are also some causal inference-based methods that can identify a part of real causal genes from those supersets, but they are just able to return a few causal genes. This is contrary to our knowledge, as many results from controlled experiments have demonstrated that a certain disease, especially cancer, is usually related to dozens or hundreds of genes. In this work, we present an effective approach for identifying causal genes from gene expression data by using a new search strategy based on non-linear regression-based independence tests, which is able to greatly reduce the search space, and simultaneously establish the causal relationships from the candidate genes to the disease variable. Extensive experiments on real-world cancer datasets show that our method is superior to the existing causal inference-based methods in three aspects: 1) our method can identify dozens of causal genes, and 1/3  ∼ 1/2 of the discovered causal genes can be verified by existing works that they are really directly related to the corresponding disease; 2) The discovered causal genes are able to distinguish the status or disease subtype of the target patient; 3) Most of the discovered causal genes are closely relevant to the disease variable.

Recurrence of Papillary Thyroid Cancer: A Systematic Appraisal of Risk Factors

CONTEXT

Thyroid cancer recurrence is associated with increased mortality and adverse outcomes. Recurrence risk is currently predicted using clinical tools, often restaging patients after treatment. Detailed understanding of recurrence risk at disease onset could lead to personalized and improved patient care.

OBJECTIVE

We aimed to perform a comprehensive bioinformatic and experimental analysis of 3 levels of genetic change (mRNA, microRNA, and somatic mutation) apparent in recurrent tumors and construct a new combinatorial prognostic risk model.

METHODS

We analyzed The Cancer Genome Atlas data (TCGA) to identify differentially expressed genes (mRNA/microRNA) in 46 recurrent vs 455 nonrecurrent thyroid tumors. Two exonic mutational pipelines were used to identify somatic mutations. Functional gene analysis was performed in cell-based assays in multiple thyroid cell lines. The prognostic value of genes was evaluated with TCGA datasets.

RESULTS

We identified 128 new potential biomarkers associated with recurrence, including 40 mRNAs, 39 miRNAs, and 59 genetic variants. Among differentially expressed genes, modulation of FN1, ITGα3, and MET had a significant impact on thyroid cancer cell migration. Similarly, ablation of miR-486 and miR-1179 significantly increased migration of TPC-1 and SW1736 cells. We further utilized genes with a validated functional role and identified a 5-gene risk score classifier as an independent predictor of thyroid cancer recurrence.

CONCLUSION

Our newly proposed risk model based on combinatorial mRNA and microRNA expression has potential clinical utility as a prognostic indicator of recurrence. These findings should facilitate earlier prediction of recurrence with implications for improving patient outcome by tailoring treatment to disease risk and increasing posttreatment surveillance.

Characterization of Proteins Regulated by Androgen and Protein Kinase a Signaling in VCaP Prostate Cancer Cells

Androgen signaling via the androgen receptor (AR) is involved in normal prostate development and prostate cancer progression. In addition to androgen binding, a variety of protein kinases, including cyclic AMP-dependent protein kinase A (PKA), can activate the AR. Although hormone deprivation, especially that of androgen, continues to be an important strategy for treating prostate cancer patients, the disease ultimately progresses to castration-resistant prostate cancer (CRPC), despite a continuous hormone-deprived environment. To date, it remains unclear which pathways in this progression are active and targetable. Here, we performed a proteomic analysis of VCaP cells stimulated with androgen or forskolin to identify proteins specific for androgen-induced and androgen-bypassing signaling, respectively. Patterns of differentially expressed proteins were quantified, and eight proteins showing significant changes in expression were identified. Functional information, including a Gene Ontology analysis, revealed that most of these proteins are involved in metabolic processes and are associated with cancer. The mRNA and protein expression of selected proteins was validated, and functional correlations of identified proteins with signaling in VCaP cells were assessed by measuring metabolites related to each enzyme. These analyses offered new clues regarding effector molecules involved in prostate cancer development, insights that are supported by the demonstration of increased expression levels of the eight identified proteins in prostate cancer patients and assessments of the progression-free interval. Taken together, our findings show that aberrant levels of eight proteins reflect molecular changes that are significantly regulated by androgen and/or PKA signaling pathways, suggesting possible molecular mechanisms of CRPC.

IMPDH2 and HPRT expression and a prognostic significance in preoperative and postoperative patients with osteosarcoma

Osteosarcoma is one of the most aggressive bone tumors in children and adolescents. Development of effective therapeutic options is still lacking due to the complexity of the genomic background. In previous work, we applied a proteomics-guided drug repurposing to explore potential treatments for osteosarcoma. Our follow-up study revealed an FDA-approved immunosuppressant drug, mycophenolate mofetil (MMF) targeting inosine-5'-phosphate dehydrogenase (IMPDH) enzymes, has an anti-tumor effect that appeared promising for further investigation and clinical trials. Profiling of IMPDH2 and hypoxanthine-guanine phosphoribosyltransferase (HPRT), key purine-metabolizing enzymes, could deepen understanding of the importance of purine metabolism in osteosarcoma and provide evidence for expanded use of MMF in the clinic. In the present study, we investigated levels of IMPDH2, and HPRT in biopsy of 127 cases and post-chemotherapy tissues in 20 cases of high-grade osteosarcoma patients using immunohistochemical (IHC) analysis. Cox regression analyses were performed to determine prognostic significance of all enzymes. The results indicated that low levels of HPRT were significantly associated with a high Enneking stage (P = 0.023) and metastatic status (P = 0.024). Univariate and multivariate analyses revealed that patients with low HPRT expression have shorter overall survival times [HR 1.70 (1.01-2.84), P = 0.044]. Furthermore, high IMPDH2/HPRT ratios were similarly associated with shorter overall survival times [HR 1.67 (1.02-2.72), P = 0.039]. Levels of the enzymes were also examined in post-chemotherapy tissues. The results showed that high IMPDH2 expression was associated with shorter metastasis-free survival [HR 7.42 (1.22-45.06), P = 0.030]. These results suggest a prognostic value of expression patterns of purine-metabolizing enzymes for the pre- and post-chemotherapy period of osteosarcoma treatment.

GTP metabolic reprogramming by IMPDH2: unlocking cancer cells' fuelling mechanism

Growing cells increase multiple biosynthetic processes in response to the high metabolic demands needed to sustain proliferation. The even higher metabolic requirements in the setting of cancer provoke proportionately greater biosynthesis. Underappreciated key aspects of this increased metabolic demand are guanine nucleotides and adaptive mechanisms to regulate their concentration. Using the malignant brain tumour, glioblastoma, as a model, we have demonstrated that one of the rate-limiting enzymes for guanosine triphosphate (GTP) synthesis, inosine monophosphate dehydrogenase-2 (IMPDH2), is increased and IMPDH2 expression is necessary for the activation of de novo GTP biosynthesis. Moreover, increased IMPDH2 enhances RNA polymerase I and III transcription directly linking GTP metabolism to both anabolic capacity as well as nucleolar enlargement historically observed as associated with cancer. In this review, we will review in detail the basis of these new discoveries and, more generally, summarize the current knowledge on the role of GTP metabolism in cancer.

Metabolic Compartmentalization at the Leading Edge of Metastatic Cancer Cells

Despite advances in targeted therapeutics and understanding in molecular mechanisms, metastasis remains a substantial obstacle for cancer treatment. Acquired genetic mutations and transcriptional changes can promote the spread of primary tumor cells to distant tissues. Additionally, recent studies have uncovered that metabolic reprogramming of cancer cells is tightly associated with cancer metastasis. However, whether intracellular metabolism is spatially and temporally regulated for cancer cell migration and invasion is understudied. In this review, we highlight the emergence of a concept, termed “membraneless metabolic compartmentalization,” as one of the critical mechanisms that determines the metastatic capacity of cancer cells. In particular, we focus on the compartmentalization of purine nucleotide metabolism (e.g., ATP and GTP) at the leading edge of migrating cancer cells through the uniquely phase-separated microdomains where dynamic exchange of nucleotide metabolic enzymes takes place. We will discuss how future insights may usher in a novel class of therapeutics specifically targeting the metabolic compartmentalization that drives tumor metastasis.

IMPDH2 promotes cell proliferation and epithelial-mesenchymal transition of non-small cell lung cancer by activating the Wnt/β-catenin signaling pathway

Inosine 5'-monophosphate dehydrogenase type II (IMPDH2) is an important enzyme involved in the biosynthesis of guanine nucleotides. Therefore, the present study aimed to investigate the potential and molecular mechanism of IMPDH2 in non-small cell lung cancer (NSCLC). Reverse transcription-quantitative PCR and immunohistochemistry were used to detect IMPDH2 expression levels in NSCLC tissues and cells. A Cell Counting Kit-8 assay, colony formation assay, flow cytometry, wound healing, Transwell assay, western blotting and immunofluorescence analyses were utilized to identify the effects of upregulated IMPDH2 levels on NSCLC cells. The expression levels of IMPDH2 have been discovered to be upregulated in several types of human cancer; however, the biological and clinical value of IMPDH2 in NSCLC remains unclear. The results of the present study revealed that the expression levels of IMPDH2 were significantly upregulated in NSCLC tissues. Furthermore, the genetic knockdown of IMPDH2 significantly hindered the proliferation, apoptosis, invasion, migration and epithelial-mesenchymal transition of NSCLC cells, whereas the overexpression of IMPDH2 achieved the opposite results. In addition, the results of the present study demonstrated that the inhibition of IMPDH2 inhibited the Wnt/β-catenin signaling pathway by decreasing the expression levels of Wnt3a and β-catenin, while increasing the expression levels of phosphorylated glycogen synthase kinase-3β in NSCLC cells. These findings of the present study indicated that IMPDH2 may promote NSCLC progression by activating the Wnt/β-catenin signaling pathway, which suggested that IMPDH2 may be a novel therapeutic target for patients with NSCLC.

Anticancer fungal natural products: Mechanisms of action and biosynthesis

Many fungal metabolites show promising anticancer properties both in vitro and in animal models, and some synthetic analogs of those metabolites have progressed into clinical trials. However, currently, there are still no fungi-derived agents approved as anticancer drugs. Two potential reasons could be envisioned: 1) lacking a clear understanding of their anticancer mechanism of action, 2) unable to supply enough materials to support the preclinical and clinic developments. In this review, we will summarize recent efforts on elucidating the anticancer mechanisms and biosynthetic pathways of several promising anticancer fungal natural products.

Exome sequencing of familial high-grade serous ovarian carcinoma reveals heterogeneity for rare candidate susceptibility genes

High-grade serous ovarian carcinoma (HGSOC) has a significant hereditary component, approximately half of which cannot be explained by known genes. To discover genes, we analyse germline exome sequencing data from 516 BRCA1/2-negative women with HGSOC, focusing on genes enriched with rare, protein-coding loss-of-function (LoF) variants. Overall, there is a significant enrichment of rare protein-coding LoF variants in the cases (p < 0.0001, chi-squared test). Only thirty-four (6.6%) have a pathogenic variant in a known or proposed predisposition gene. Few genes have LoF mutations in more than four individuals and the majority are detected in one individual only. Forty-three highly-ranked genes are identified with three or more LoF variants that are enriched by three-fold or more compared to GnomAD. These genes represent diverse functional pathways with relatively few involved in DNA repair, suggesting that much of the remaining heritability is explained by previously under-explored genes and pathways.

The expression and prognostic role of IMPDH2 in ovarian cancer

OBJECT

Inosine 5'-monophosphate dehydrogenase type II (IMPDH2), as an oncogene, is reported to be involved in tumor formation and progression. However, the role of IMPDH2 in ovarian cancer remains unclear. Present study is aimed to investigate the expression and clinical significance of IMPDH2 in ovarian cancer.

METHODS

The mRNA and protein levels of IMPDH2 were measured in 126 ovarian cancer and matched adjacent normal tissues by quantificational real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC), respectively. Then, the association of IMPDH2 with clinicalpathological characters and prognosis was further evaluated.

RESULTS

Significant higher mRNA levels of IMPDH2 were observed in ovarian cancer compared with those in normal tissues (P < 0.001). IHC results shown the high-expression rate of IMPDH2 in ovarian cancer was 56.3%, which was obviously higher compared with that in normal tissues (23.8%, P < 0.0001). Moreover, IMPDH2 high-expression significantly correlated with tumor types and Federation International of Gynecology and Obstetrigue (FIGO) stages in ovarian cancer (P < 0.05). IMPDH2 overexpression predicted poorer prognosis and could serve as an independent prognostic factor.

CONCLUSIONS

IMPDH2 is highly expressed in ovarian cancer and correlates with prognosis, which may serve as a potential prognostic biomarker.

Dynamic compartmentalization of purine nucleotide metabolic enzymes at leading edge in highly motile renal cell carcinoma

Compartmentalization is vital for biological systems at multiple levels, including biochemical reactions in metabolism. Organelle-based compartments such as mitochondria and peroxisomes sequester the responsible enzymes and increase the efficiency of metabolism while simultaneously protecting the cell from dangerous intermediates, such as radical oxygen species. Recent studies show intracellular nucleotides, such as ATP and GTP, are heterogeneously distributed in cells with high concentrations at the lamellipodial and filopodial projections, or leading edge. However, the intracellular distribution of purine nucleotide enzymes remains unclear. Here, we report the enhanced localization of GTP-biosynthetic enzymes, including inosine monophosphate dehydrogenase (IMPDH isotype 1 and 2), GMP synthase (GMPS), guanylate kinase (GUK1) and nucleoside diphosphate kinase-A (NDPK-A) at the leading edge in renal cell carcinoma cells. They show significant co-localization at the membrane subdomain, and their co-localization pattern at the membrane is distinct from that of the cell body. While other purine nucleotide biosynthetic enzymes also show significant localization at the leading edge, their co-localization pattern with IMPDH is divergent. In contrast, a key glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), predominantly localized in the cytoplasm. Mechanistically, we found that plasma membrane localization of IMPDH isozymes requires active actin polymerization. Our results demonstrate the formation of a discrete metabolic compartment for localized purine biosynthesis at the leading edge, which may promote localized nucleotide metabolism for cell migration and metastasis in cancers.

Inosine monophosphate dehydrogenase 2 as a marker of aggressive and advanced prostate cancer

Introduction

There is a need for a new biochemical marker of aggressive prostate cancer (PCa). Inosine monophosphate dehydrogenase 2 (IMPDH2) is a candidate for such a marker – its activity is increased in certain tumors and neoplastic cell lines, including PCa, and may correlate with cancer aggressiveness.

Material and methods

IMPDH2 levels were measured in blood samples from 34 PCa patients. The results were analyzed and correlated with prostate-specific antigen (PSA), digital rectal examination (DRE), Gleason score, risk groups according to d'Amico and metastatic disease. Twenty healthy (non-PCa) patients served as the control group.

Results

There was no significant difference in IMPDH2 level between the PCa and control group, and no significant correlation between PSA and IMPDH2. IMPDH2 levels were significantly higher in the DRE (+) patients (148.5 ±174.8 vs. 33.4 ±46.4, p <0.05), in patients with metastatic disease (100.1 ±139.0 vs. 25.3 ±25.9, p <0.05) and in the high-risk group according to d'Amico (93.4 ±129.2 vs. 18.8 ±10.4, p <0.05). There was a significant correlation between the Gleason score and IMPDH2.

Conclusions

These results suggest that IMPDH2 is a promising candidate as a biomarker for those with advanced PCa and those at high risk of progression towards advanced PCa.

Immune Response-Dependent Assembly of IMP Dehydrogenase Filaments

Inosine monophosphate dehydrogenase (IMPDH) catalyzes the conversion of IMP to xanthosine monophosphate, the rate-limiting step in de novo guanosine monophosphate (GMP) synthesis. In cultured cells, IMPDH polymerizes into micron-scale filamentous structures when GMP synthesis is inhibited by depletion of purine precursors or by various drugs, including mycophenolic acid, ribavirin, and methotrexate. IMPDH filaments also spontaneously form in undifferentiated mouse embryonic stem cells and induced pluripotent stem cells, hinting they might function in various highly proliferative cell types. Therefore, we investigated IMPDH filament formation in human and murine T cells, which rely heavily on de novo guanine nucleotide synthesis to rapidly proliferate in response to antigenic challenge. We discovered extensive in vivo IMPDH filament formation in mature T cells, B cells, and other proliferating splenocytes of normal, adult B6 mice. Both cortical and medullary thymocytes in young and old mice also showed considerable assembly of IMPDH filaments. We then stimulated primary human peripheral blood mononuclear cells ex vivo with T cell mitogens phytohemagglutinin (PHA), concanavalin A (ConA), or antibodies to CD3 and CD28 for 72 h. We detected IMPDH filaments in 40–60% of T cells after activation compared to 0–10% of unstimulated T cells. Staining of activated T cells for the proliferation marker Ki-67 also showed an association between IMPDH filament formation and proliferation. Additionally, we transferred ovalbumin-specific CD4⁺ T cells from B6.OT-II mice into B6.Ly5a recipient mice, challenged these mice with ovalbumin, and harvested spleens 6 days later. In these spleens, we identified abundant IMPDH filaments in transferred T cells by immunofluorescence, indicating that IMPDH also polymerizes during in vivo antigen-specific T cell activation. Overall, our data indicate that IMPDH filament formation is a novel aspect of T cell activation and proliferation, and that filaments might be useful morphological markers for T cell activation. The data also suggest that in vivo IMPDH filament formation could be occurring in a variety of proliferating cell types throughout the body. We propose that T cell activation will be a valuable model for future experiments probing the molecular mechanisms that drive IMPDH polymerization, as well as how IMPDH filament formation affects cell function.

Clinical significance of bromodomain-containing protein 7 and its association with tumor progression in prostate cancer

Prostate cancer (PCa) is a common malignancy in males. The current study assessed the clinical significance of bromodomain-containing protein 7 (BRD7) and its association with PCa tumor progression. Serum and tissue expression levels of BRD7 were analyzed by reverse transcription-quantitative polymerase chain reaction. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic value of BRD7. Kaplan-Meier survival analysis and Cox regression analysis were performed to assess the prognostic performance of BRD7. The association of BRD7 with cell behavior was investigated by transfection with a pcDNA3.1-BRD7 vector. The results revealed that serum and tissue BRD7 expression levels were significantly decreased in PCa samples compared with normal controls (P<0.001). BRD7 expression was significantly associated with the pathological stage (P=0.037), lymph node metastasis (P=0.009) and TNM stage (P=0.010). An area under the ROC curve of 0.864 was obtained, with a sensitivity and specificity of 77.0 and 83.3%, respectively. Low BRD7 expression was significantly associated with a shorter survival time in both overall survival analysis (P=0.003) and cancer-specific survival analysis (P=0.029). Furthermore, BRD7 appeared to serve as an independent prognostic factor for PCa. The proliferation, migration and invasion of PCa cells were suppressed by BRD7 overexpression. In summary, downregulation of BRD7 in PCa may be involved in tumor progression and serve as an effective diagnostic and prognostic biomarker.

Integrative analysis of promising molecular biomarkers and pathways for coronary artery disease using WGCNA and MetaDE methods

The present study aimed to examine the molecular mechanisms of coronary artery disease (CAD). A total of four microarray datasets (training dataset no. GSE12288; validation dataset nos. GSE20680, GSE20681 and GSE42148) were downloaded from the Gene Expression Omnibus database, which included CAD and healthy samples. Weighted gene co-expression network analysis was applied to identify highly preserved modules across the four datasets. Differentially expressed genes (DEGs) with significant consistency in the four datasets were selected using the MetaDE method. The overlapping genes amongst the DEGs with significant consistency and in the preserved modules were used to construct a protein-protein interaction (PPI) network, followed by functional enrichment analysis. A total of 11 modules were established in the training dataset, and five of them were highly preserved across all four datasets, including 873 genes. There was a total of 836 DEGs with significant consistency in the four datasets. A total of 177 overlapping genes were selected, with which a PPI network was constructed. The top five genes of the PPI network were identified based on their degrees: LCK proto-oncogene, Src family tyrosine kinase (LCK), euchromatic histone lysine methyltransferase 2 (EHMT2), inosine monophosphate dehydrogenase 2 (IMPDH2), protein phosphatase 4 catalytic subunit (PPP4C) and ζ-chain of T-cell receptor associated protein kinase 70 (ZAP70). Genes in the PPI network were significantly involved in a number of Kyoto Encyclopedia Genes and Genomes pathways, including the ‘natural killer cell mediated cytotoxicity’, ‘primary immunodeficiency’ and ‘Fc gamma R-mediated phagocytosis’ pathways. LCK, EHMT2, IMPDH2, PPP4C and ZAP70 are suggested as promising molecular biomarkers for CAD. The ‘natural killer cell mediated cytotoxicity’, ‘primary immunodeficiency’ and ‘Fc gamma R-mediated phagocytosis’ pathways may serve important roles in CAD.

A hnRNP K⁻AR-Related Signature Reflects Progression toward Castration-Resistant Prostate Cancer

The major challenge in castration-resistant prostate cancer (CRPC) remains the ability to predict the clinical responses to improve patient selection for appropriate treatments. The finding that androgen deprivation therapy (ADT) induces alterations in the androgen receptor (AR) transcriptional program by AR coregulators activity in a context-dependent manner, offers the opportunity for identifying signatures discriminating different clinical states of prostate cancer (PCa) progression. Gel electrophoretic analyses combined with western blot showed that, in androgen-dependent PCa and CRPC in vitro models, the subcellular distribution of spliced and serine-phosphorylated heterogeneous nuclear ribonucleoprotein K (hnRNP K) isoforms can be associated with different AR activities. Using mass spectrometry and bioinformatic analyses, we showed that the protein sets of androgen-dependent (LNCaP) and ADT-resistant cell lines (PDB and MDB) co-immunoprecipitated with hnRNP K varied depending on the cell type, unravelling a dynamic relationship between hnRNP K and AR during PCa progression to CRPC. By comparing the interactome of LNCaP, PDB, and MDB cell lines, we identified 51 proteins differentially interacting with hnRNP K, among which KLK3, SORD, SPON2, IMPDH2, ACTN4, ATP1B1, HSPB1, and KHDRBS1 were associated with AR and differentially expressed in normal and tumor human prostate tissues. This hnRNP K–AR-related signature, associated with androgen sensitivity and PCa progression, may help clinicians to better manage patients with CRPC.

Expression of ribosomal and actin network proteins and immunochemotherapy resistance in diffuse large B cell lymphoma patients

Diffuse large B cell lymphoma (DLBCL) patients with early relapse or refractory disease have a very poor outcome. Immunochemotherapy resistance will probably, also in the era of targeted drugs, remain the major cause of treatment failure. We used proteomic mass spectrometry to analyse the global protein expression of micro-dissected formalin-fixed paraffin-embedded tumour tissues from 97 DLBCL patients: 44 with primary refractory disease or relapse within 1 year from diagnosis (REF/REL), and 53 who were progression-free more than 5 years after diagnosis (CURED). We identified 2127 proteins: 442 were found in all patients and 102 were differentially expressed. Sixty-five proteins were overexpressed in REF/REL patients, of which 46 were ribosomal proteins (RPs) compared with 2 of the 37 overexpressed proteins in CURED patients (P = 7·6 × 10^-10 ). Twenty of 37 overexpressed proteins in CURED patients were associated with actin regulation, compared with 1 of 65 in REF/REL patients (P = 1·4 × 10^-9 ). Immunohistochemical staining showed higher expression of RPS5 and RPL17 in REF/REL patients while MARCKS-like protein, belonging to the actin network, was more highly expressed in CURED patients. Even though functional studies aimed at individual proteins and protein interactions to evaluate potential clinical effect are needed, our findings suggest new mechanisms behind immunochemotherapy resistance in DLBCL.

The nuclear DEK interactome supports multi-functionality

DEK is an oncoprotein that is overexpressed in many forms of cancer and participates in numerous cellular pathways. Of these different pathways, relevant interacting partners and functions of DEK are well described in regard to the regulation of chromatin structure, epigenetic marks, and transcription. Most of this understanding was derived by investigating DNA-binding and chromatin processing capabilities of the oncoprotein. To facilitate the generation of mechanism-driven hypotheses regarding DEK activities in underexplored areas, we have developed the first DEK interactome model using tandem-affinity purification and mass spectrometry. With this approach, we identify IMPDH2, DDX21, and RPL7a as novel DEK binding partners, hinting at new roles for the oncogene in de novo nucleotide biosynthesis and ribosome formation. Additionally, a hydroxyurea-specific interaction with replication protein A (RPA) was observed, suggesting that a DEK-RPA complex may form in response to DNA replication fork stalling. Taken together, these findings highlight diverse activities for DEK across cellular pathways and support a model wherein this molecule performs a plethora of functions.

One-carbon metabolism and nucleotide biosynthesis as attractive targets for anticancer therapy

Cancer-related metabolism has recently emerged as one of the “hallmarks of cancer”. It has several important features, including altered metabolism of glucose and glutamine. Importantly, altered cancer metabolism connects different biochemical pathways into the one fine-tuned metabolic network, which stimulates high proliferation rates and plasticity to malignant cells. Among the keystones of cancer metabolism are one-carbon metabolism and nucleotide biosynthesis, which provide building blocks to anabolic reactions. Accordingly, the importance of these metabolic pathways for anticancer therapy has well been documented by more than fifty years of clinical use of specific metabolic inhibitors – methotrexate and nucleotides analogs. In this review we discuss one-carbon metabolism and nucleotide biosynthesis as common and specific features of many, if not all, tumors. The key enzymes involved in these pathways also represent promising anti-cancer therapeutic targets. We review different aspects of these metabolic pathways including their biochemistry, compartmentalization and expression of the key enzymes and their regulation at different levels. We also discuss the effects of known inhibitors of these pathways as well as the recent data on other enzymes of the same pathways as perspective pharmacological targets.

Argininosuccinate Synthase 1 is a Metabolic Regulator of Colorectal Cancer Pathogenicity

Like many cancer types, colorectal cancers have dysregulated metabolism that promotes their pathogenic features. In this study, we used the activity-based protein profiling chemoproteomic platform to profile cysteine-reactive metabolic enzymes that are upregulated in primary human colorectal tumors. We identified argininosuccinate synthase 1 (ASS1) as an upregulated target in primary human colorectal tumors and show that pharmacological inhibition or genetic ablation of ASS1 impairs colorectal cancer pathogenicity. Using metabolomic profiling, we show that ASS1 inhibition leads to reductions in the levels of oncogenic metabolite fumarate, leading to impairments in glycolytic metabolism that supports colorectal cancer cell pathogenicity. We show here that ASS1 inhibitors may represent a novel therapeutic approach for attenuating colorectal cancer through compromising critical metabolic and metabolite signaling pathways and demonstrate the utility of coupling chemoproteomic and metabolomic strategies to map novel metabolic regulators of cancer.

High expression of IMPDH2 is associated with aggressive features and poor prognosis of primary nasopharyngeal carcinoma

Inosine monophosphate dehydrogenase type II (IMPDH2) has been shown to play critical roles in the development and progression of several human cancers. However, little is known about IMPDH2 expression and its clinical significance in nasopharyngeal carcinoma (NPC). Western blotting, qRT-PCR and immunohistochemistry were employed to evaluate IMPDH2 expression in NPC cell lines and tissues. In our study, elevated expression of IMPDH2 was observed at both the protein and mRNA levels in NPC cell lines than in NPEC2 Bmi-1. IMPDH2 protein expression was markedly higher in NPC tissues than in adjacent non-tumorous tissues. Moreover, IMPDH2 expression in NPC correlated with several clinicopathological parameters, including T classification (P = 0.023), TNM stage (P = 0.020), distant metastasis (P = 0.001) and death (P = 0.002). Further Cox regression analysis suggested that IMPDH2 expression was an independent prognostic factor for overall survival (P = 0.001) and disease-free survival (P < 0.001). In addition, stratified survival analysis showed that high expression of IMPDH2 could be a prognostic factor for NPC patients with TNM stage I/II (OS: P = 0.012; DMFS: P = 0.007), TNM stage III/IV (OS: P = 0.028; DMFS: P = 0.020). Our study demonstrates IMPDH2 may be served as an independent prognostic biomarker for NPC patients, in which high IMPDH expression suggests poor prognosis of NPC patients.

Withaferin A inhibits in vivo growth of breast cancer cells accelerated by Notch2 knockdown

The present study offers novel insights into the molecular circuitry of accelerated in vivo tumor growth by Notch2 knockdown in triple-negative breast cancer (TNBC) cells. Therapeutic vulnerability of Notch2-altered growth to a small molecule (withaferin A, WA) is also demonstrated. MDA-MB-231 and SUM159 cells were used for the xenograft studies. A variety of technologies were deployed to elucidate the mechanisms underlying tumor growth augmentation by Notch2 knockdown and its reversal by WA, including Fluorescence Molecular Tomography for measurement of tumor angiogenesis in live mice, Seahorse Flux analyzer for ex vivo measurement of tumor metabolism, proteomics, and Luminex-based cytokine profiling. Stable knockdown of Notch2 resulted in accelerated in vivo tumor growth in both cells reflected by tumor volume and/or latency. For example, the wet tumor weight from mice bearing Notch2 knockdown MDA-MB-231 cells was about 7.1-fold higher compared with control (P < 0.0001). Accelerated tumor growth by Notch2 knockdown was highly sensitive to inhibition by a promising steroidal lactone (WA) derived from a medicinal plant. Molecular underpinnings for tumor growth intensification by Notch2 knockdown included compensatory increase in Notch1 activation, increased cellular proliferation and/or angiogenesis, and increased plasma or tumor levels of growth stimulatory cytokines. WA administration reversed many of these effects providing explanation for its remarkable anti-cancer efficacy. Notch2 functions as a tumor growth suppressor in TNBC and WA offers a novel therapeutic strategy for restoring this function.

Elevated expression of IMPDH2 is associated with progression of kidney and bladder cancer

Novel molecular markers for cancer progression are valuable for the diagnosis and evaluation of treatment efficacies of the diseases. Expression of inosine 5'-monophosphate dehydrogenase type II (IMPDH2), a rate-limiting enzyme in the de novo guanine nucleotide biosynthesis, is up-regulated in various neoplasms, including prostate cancer and patient serum. However, whether IMPDH2 can serve as a biomarker for other urologic cancers is unknown. Paired patient tissue macroarrays were analyzed by immunohistochemistry, the IMPDH2 protein expression in these tissues was quantitated and expressed as immunoreactivity scores. Compared with non-cancerous tissues, IMPDH2 protein expression levels were significantly upregulated in kidney and bladder cancer, but no difference in testis cancer. In addition, expression of IMPDH2 was not associated with the disease clinical stages and pathological features. The findings suggest that overexpressed IMPDH2 can be used as a biomarker for kidney and bladder cancer diagnosis and is a potential therapeutic target for the diseases.