Role of purine metabolism in regulation of signal transduction in human carcinoma cells

miR-10b-5p-mediated upregulation of PIEZO1 predicts poor prognosis and links to purine metabolism in breast cancer

BACKGROUND

Increasing evidence has reported the critical roles of PIEZO1 in organism. However, the knowledge of PIEZO1 in human cancers is still inadequate.

METHODS

In silico analyses and experimental validation were performed to analyze PIEZO1's expression, prognostic values and potential upstream/downstream mechanism in breast cancer.

RESULTS

PIEZO1 was significantly overexpressed in human breast cancer cell lines and tissue samples. PIEZO1 expression was statistically positively associated with malignant progression and short survival of breast cancer. miR-10b-5p downregulation was partially responsible for PIEZO1 upregulation in breast cancer. Further exploration revealed that PIEZO1 might exert its function by regulating purine metabolism (especially GUK1, POLD1 and APRT) in breast cancer.

CONCLUSIONS

Collectively, the current study elucidated an important role of PIEZO1 in breast cancer and providing key clues for identifying PIEZO1 as a therapeutic target and prognostic biomarker in breast cancer.

Comprehensive Analysis of Prognostic Value and Immune Infiltration of the NT5DC Family in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world, and its incidence is obviously increasing. The NT5DC family has been shown to be involved in the progression of many tumors. However, the biological function of NT5DC family members in HCC is still not well understood.

Methods

Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), UALCAN, Kaplan–Meier plotter, cBioPortal, GeneMANIA, Metascape, and TIMER were applied to assess the biological function of NT5DC family members in HCC.

Results

Most of the NT5DC family members were highly expressed in HCC. High expression of NT5C2, NT5DC2, and NT5DC3 was closely associated with higher tumor stage and poor overall survival (OS). In addition, high NT5DC2 and NT5DC3 expression also predicted poor disease-free survival (DFS). Enrichment analysis revealed that the NT5DC family in HCC mainly involved the IMP metabolic process, purine ribonucleoside monophosphate metabolic process, and purine nucleoside monophosphate metabolic process. The expression of NT5DC family members was closely related to the infiltration of some immune cells, such as B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells.

Conclusion

Our findings provided new insights into the biological function and prognostic value of NT5DC family members in HCC.

Protection-free one-pot synthesis of 2'-deoxynucleoside 5'-triphosphates and DNA polymerization

By differentiating the functional groups on nucleosides, we have designed and developed a one-pot synthesis of deoxyribonucleoside 5'-triphosphates without any protection on the nucleosides. A facile synthesis is achieved by generating an in situ phosphitylating reagent that reacts selectively with the 5'-hydroxyl groups of the unprotected nucleosides. The synthesized triphosphates are of high quality and can be effectively incorporated into DNAs by DNA polymerase. This novel approach is straightforward and cost-effective for triphosphate synthesis.

Expression patterns of AMP-deaminase isozymes in human hepatocellular carcinoma (HCC)

BACKGROUND

AMP-deaminase (EC 3.5.4.6) is an enzyme of nucleotide breakdown involved in regulation of energetic metabolism in mammalian cells. The enzyme is coded by a family of three independent genes (AMPD1, AMPD2 and AMPD3), synthesizing three different isozymes. In mammalian liver, the reaction catalyzed by AMP-deaminase constitutes a rate-limiting step in adenine nucleotide catabolism. In neoplastic liver, adenine nucleotide catabolism is a subject of many modifications, which influence the expression of genes synthesizing enzymes regulating this pathway.

AIMS

The experimental studies presented here illustrate the expression of AMPD genes in human liver neoplasm tumor (HCC, hepatocellular carcinoma).

METHODS

RT-PCR and Western blotting methods were used for determining of the goal mentioned above.

RESULTS AND CONCLUSION

Expression level of AMPD gene family in the tumorous fragment (HCC tumor) of neoplastic liver did not differ substantially from that found in the nontumorous (cirrhotic) fragment of the organ. In this case the expression of AMPD2 gene was prevailing. AMPD2 was the main isoform of AMP-deaminase identified in two liver fragments compared. This is a first report evidencing the pattern of AMPD genes expression in neoplastic human liver.

Nucleoside transporter expression and activity is regulated during granulocytic differentiation of NB4 cells in response to all-trans-retinoic acid

NB4 cells express multiple nucleoside transporters (NTs), including: hENT1 (es), and hENT2 (ei), and the CNT subtype referred to as, csg; a concentrative sensitive guanosine specific transporter. csg activity is a distinguishing feature of the NB4 cell line and its presence suggests a particular requirement of these cells for guanosine salvage. Proliferation and differentiation pathways determine, in part, the number of NTs in cells and tissues. In this study, all-trans-retinoic acid (ATRA)-induced granulocytic differentiation of NB4 cells resulted in biphasic changes in guanosine transport. Transient increases in csg and es activity, the result of an increase in V(max) (pmol/muls) of both transporter systems, served as early markers of differentiation while expression of a fully differentiated phenotype was accompanied by a selective loss of csg activity and the return of es activity to that of proliferating cells. Intracellular incorporation of [(3)H]-guanosine decreased as cells matured despite increased transport rates and suggested a reduced intracellular requirement of NB4-granulocytes compared to their proliferating counterparts. Whether a loss of csg activity could serve to assess clinical response to differentiation therapies is not known. Nitrobenzylthioinosine (NBMPR) binding sites within nuclear membrane (NM) preparations, suggested the presence of functional intracellular NTs. An increase in plasma membrane (PM) associated transporters coincided with the early increase in guanosine transport and a decrease in NBMPR binding to NM fractions and suggests that intracellular NTs may serve as a reserve pool for translocation to the (PM) when additional transport capacity is required. The modulation of transporters during differentiation could potentially regulate drug bioavailability and cytotoxicity and should be evaluated prior to combining differentiating agents with traditional nucleoside analogs in the treatment of APL.

Cloning and functional characterization of GMPR2, a novel human guanosine monophosphate reductase, which promotes the monocytic differentiation of HL-60 leukemia cells

PURPOSE

To identify the biological function of a novel molecule which shows high homology with human guanosine monophosphate reductase (GMPR) and is named GMPR2.

METHODS

GMPR2 cDNA was cloned from the cDNA library of human dendritic cells and was characterized by Bioinformatics. The expression pattern of GMPR2 was analyzed by Northern blotting. The enzymatic activity of the purified recombinant GMPR2 protein was determined using a spectrophotometric assay. HL-60 leukemia cells were transfected with GMPR2 and the expression of CD14 and myeloperoxidase (MPO) in HL-60 cells with and without 12- o-tetra-decanoyl-phorbol-13-acetate (TPA) induction was monitored by FACS analysis.

RESULTS

The novel gene contained ten exons and nine introns and was mapped to 14q11-21. Northern blotting indicated a ubiquitous expression of GMPR2 mRNA in most of the human tissues and cancer cell lines investigated. The recombinant GMPR2 protein was able to reduce GMP. The expression of CD14 and MPO in HL-60 leukemia cells overexpressing GMPR2 clearly increased after induction by TPA.

CONCLUSIONS

GMPR2 is a novel human GMP reductase, and overexpression of GMPR2 can promote the monocytic differentiation of HL-60 leukemia cells.

Cell imaging and morphology: application to studies of inherited purine metabolic disorders

A number of inherited or drug-induced metabolic disorders involving dysfunctions in purines and pyrimidines are strongly associated with neurological dysfunction, e.g., Lesch Nyhan syndrome. Such disorders have been studied extensively using biochemical and molecular techniques in order to examine how such defects occur, sometimes using in vitro models based upon cultured neuroblastoma cell lines. However, these metabolic dysfunctions may manifest their effects in other ways, such as impaired synaptic transmission and gross abnormalities in neuronal growth and differentiation. This review outlines the latter novel facet of purine research. It is proposed that by employing cell imaging techniques and cultured neuroblastoma cell lines, believed to model the nervous system, significant insights into how inherited disorders of purine metabolism affect neuronal development can be obtained. This review provides an example of the application of these techniques to understand the etiology of Lesch Nyhan syndrome, and encourages further study of the role of purines and pyrimidines in the development of the nervous system.