OBJECTIVE: To analyze the clinical characteristics and pathogenic gene in a Chinese pedigree affected with mitochondrial DNA depletion syndrome 8A (MTDPS8A). METHODS: Whole exome sequencing was carried out for the patient. Sanger sequencing was used to verify the results, and PolyPhen-2 and PROVEAN software were used to predict the impact of amino acid changes on the function of the protein. RESULTS: The patient, a two-month-old female, was admitted to the hospital for poor milk intake and poor mental response. Her clinical manifestations included feeding difficulty, shortness of breath and low muscle tone. Auxiliary laboratory test indicated that the infant was underdeveloped with abnormal liver, kidney, and heart functions accompanied by hyperlacticacidemia. She responded poorly to treatment and eventually died. Sequencing revealed that the child has carried compound heterozygous missense variants of the RRM2B gene, namely c.16delA (p.R6Gfs*22) and c.175G>C (p.A59P), which were respectively inherited from her father and mother, and both were newly discovered pathologic variants. CONCLUSION The c.16delA and c.175G>C compound heterozygous variants of the RRM2B gene probably underlay the pathogenesis of MTDPS8A. Above finding has strengthened the understanding of the clinical feature and genetic etiology of this disease and expanded the mutation spectrum of the RRM2B gene.
Cell Cycle Proteins ; Child ; China ; DNA, Mitochondrial/genetics* ; Female ; Genetic Testing ; Humans ; Infant ; Mutation ; Pedigree ; Ribonucleotide Reductases ; Whole Exome Sequencing

OBJECTIVE: To investigate the effects of ribonucleotide reductase catalytic subunit M1 (RRM1) gene silencing on drug resistance of human breast cancer cell line MCF-7/R. METHODS: We established a paclitaxel-resistant breast cancer MCF-7 cell line (MCF-7/R) by exposing the cells to high-concentration paclitaxel in a short time. Small interfering RNAs (siRNAs) targeting RRM1 were designed to silence RRM1 expression in human breast cancer MCF-7/R cells. MTT assay was used to detect the IC values and the sensitivity to paclitaxel in the cells with or without siRNA transfection. The changes in the proliferative activity of MCF7 and MCF-7/R cells following RRM1 gene silencing were evaluated using EdU assay. Flow cytometry was used to analyze the cell apoptosis and cell cycle changes. We assessed the effect of RRM1 gene silencing and paclitaxel on the tumor growth in a nude mouse model bearing subcutaneous xenografts with or without siRNA transfection. RESULTS: We detected significantly higher expressions of RRM1 at both the mRNA and protein levels in the drug-resistant MCF- 7/R cells than in the parental MCF-7 cells ( < 0.01). Transfection with the specific siRNAs significantly reduced the expression of RRM1 in MCF-7/R cells ( < 0.05), which showed a significantly lower IC value of paclitaxel than the cells transfected with the negative control siRNA ( < 0.05). RRM1 silencing significantly inhibited the proliferation ( < 0.01) and enhanced the apoptosis-inducing effect of paclitaxel in MCF-7/R cells ( < 0.001); RRM1 silencing also resulted in obviously reduced Akt phosphorylation, suppressed Bcl-2 expression and promoted the expression of p53 protein in MCF-7/R cells. In the tumor-bearing nude mice, the volume of subcutaneously transplanted tumors was significantly smaller in MCF-7/R/siRNA+ PTX group than in the other groups ( < 0.001). CONCLUSIONS RRM1 gene silencing can reverse paclitaxel resistance in human breast cancer cell line MCF-7/R by promoting cell apoptosis.
Animals ; Apoptosis ; Breast Neoplasms ; Drug Resistance, Neoplasm ; Gene Silencing ; Humans ; MCF-7 Cells ; Mice ; Mice, Nude ; Paclitaxel ; RNA, Small Interfering ; Ribonucleotide Reductases ; Tumor Suppressor Proteins

Deoxyribonucleotides (dNTPs) are important for the efficient growth of DNA viruses. Therefore, many DNA viruses have strategies for the upregulation of cellular dNTP levels. Both α- and γ-herpesviruses encode functional homologs of cellular dNTP anabolic enzymes, including the class I ribonucleotide reductase (RNR) large (R1) and small (R2) subunits, whereas β-herpesviruses modulate host cells to induce genes that increase dNTP levels. Interestingly, β-herpesviruses still express the nonfunctional RNR R1 subunit. However, it is not clear why β-herpesviruses still carry inactive R1 homologs. Recently, the R1 homologs of herpesviruses have been shown to inhibit innate immune signaling pathways. In particular, both functional and nonfunctional R1 homologs target receptor-interacting protein kinase 1 (RIP1) and inhibit RIP1-mediated signaling pathways to promote viral replication. Here, we summarize recent findings on the activity of herpesviral R1 homologs and discuss their roles in the regulation of innate immune signaling pathways.
Deoxyribonucleotides ; DNA Viruses ; Herpesviridae ; Protein Kinases ; Ribonucleotide Reductases* ; Up-Regulation

To explore the role of the special AT rich sequence binding protein-1 (SATB1) and ribonucleotide reductase M2 (RRM2) in enhancing malignant progression of non-Hodgkin lymphoma (NHL). 
 Methods: A total of 42 NHL and 42 chronic lymphadenitis patients were recruited. The protein expressions of SATB1 and RRM2 in cervical lymph nodes were determined by Western blot. After overexpression of SATB1, siSATB1 or siRRM2, the mRNA levels of SATB1 and RRM2 in cells were analyzed via RT-PCR, the cell proliferation was evaluated via MTT and EdU assays, while the migration and invasion of cells were assessed by transwell assays.
 Results: Compared with chronic lymphadenitis, the expressions of SATB1 and RRM2 in NHL patients were up-regulated. There was positive correlation between SATB1 and RRM2 in NHL patients. RRM2 mRNA level was up-regulated after transfection of SATB1 and down-regulated after transfection of siSATB1. Overexpression of SATB1 increased tumor cell proliferation, migration and invasion, while knockdown of RRM2 reversed those phenomena.
 Conclusion: SATB1 functions as an oncogene and promotes tumor cell proliferation, migration and invasion by up-regulation of RRM2 in NHL.
Cell Cycle Proteins ; genetics ; physiology ; Cell Movement ; genetics ; Cell Proliferation ; genetics ; Down-Regulation ; Gene Expression Regulation, Neoplastic ; genetics ; Humans ; Lymph Nodes ; chemistry ; Lymphoma, Non-Hodgkin ; Matrix Attachment Region Binding Proteins ; genetics ; physiology ; Neoplasm Invasiveness ; genetics ; Oncogenes ; genetics ; physiology ; RNA, Messenger ; RNA, Small Interfering ; Ribonucleoside Diphosphate Reductase ; Ribonucleotide Reductases ; genetics ; physiology ; Signal Transduction ; Transcription Factors ; Transcriptional Activation ; Transfection ; Tumor Cells, Cultured ; Up-Regulation

BACKGROUND/AIMS: Ribonucleotide reductase subunit M2 (RRM2) catalyzes the production of deoxynucleotide triphosphates, which are necessary for DNA synthesis. RRM2 has been reported to play an active role in tumor progression, and elevated RRM2 levels have been correlated with poor prognosis for colorectal cancer patients. This study aimed to elucidate the prognostic significance of RRM2 protein expression in hepatocellular carcinoma after surgery. METHODS: RRM2 protein expression was evaluated using immunohistochemistry in tumor tissues from 259 hepatocellular carcinoma patients who underwent curative hepatectomy. RESULTS: High RRM2 expression was observed in 210 of 259 patients (81.1%) with hepatocellular carcinomas. High RRM2 expression was significantly associated with viral etiology (p=0.035) and liver cirrhosis (p=0.036). High RRM2 expression was correlated with early recurrence (p=0.004) but not with late recurrence (p=0.144). Logistic regression analysis revealed that high RRM2 expression (p=0.040) and intrahepatic metastasis (p<0.001) were independent predictors of early recurrence. High RRM2 expression unfavorably influenced both shorter recurrence-free survival (p=0.011) and shorter disease-specific survival (p=0.002) and was an independent predictor of shorter disease-specific survival (p=0.008). CONCLUSIONS: High RRM2 protein expression might be a useful marker for predicting early recurrence and may be a marker for poor prognosis of hepatocellular carcinoma after curative hepatectomy.
Adolescent ; Adult ; Aged ; Carcinoma, Hepatocellular/*metabolism/surgery ; Disease-Free Survival ; Female ; Hepatectomy ; Humans ; Immunohistochemistry ; Liver Neoplasms/*metabolism/surgery ; Logistic Models ; Male ; Middle Aged ; Neoplasm Recurrence, Local/*metabolism ; Prognosis ; Ribonucleoside Diphosphate Reductase/*metabolism ; Tumor Markers, Biological/*metabolism ; Young Adult

No abstract available.
Carcinoma, Hepatocellular/*metabolism ; Female ; Humans ; Liver Neoplasms/*metabolism ; Male ; Neoplasm Recurrence, Local/*metabolism ; Ribonucleoside Diphosphate Reductase/*metabolism ; Tumor Markers, Biological/*metabolism

Eukaryotic cells contain numerous iron-requiring proteins such as iron-sulfur (Fe-S) cluster proteins, hemoproteins and ribonucleotide reductases (RNRs). These proteins utilize iron as a cofactor and perform key roles in DNA replication, DNA repair, metabolic catalysis, iron regulation and cell cycle progression. Disruption of iron homeostasis always impairs the functions of these iron-requiring proteins and is genetically associated with diseases characterized by DNA repair defects in mammals. Organisms have evolved multi-layered mechanisms to regulate iron balance to ensure genome stability and cell development. This review briefly provides current perspectives on iron homeostasis in yeast and mammals, and mainly summarizes the most recent understandings on iron-requiring protein functions involved in DNA stability maintenance and cell cycle control.
Animals ; Cell Cycle Checkpoints ; DNA ; metabolism ; DNA Repair ; DNA Replication ; Hemeproteins ; genetics ; metabolism ; Iron ; chemistry ; metabolism ; Iron-Sulfur Proteins ; genetics ; metabolism ; Ribonucleotide Reductases ; genetics ; metabolism ; Yeasts ; metabolism

OBJECTIVE: Meningiomas represent 18-20% of all intracranial tumors and have a 20-50% 10-year recurrence rate, despite aggressive surgery and irradiation. Hydroxyurea, an inhibitor of ribonucleotide reductase, is known to inhibit meningioma cells by induction of apoptosis. We report the long-term follow-up result of hydroxyurea therapy in the patients with recurrent meningiomas. METHODS: Thirteen patients with recurrent WHO grade I or II meningioma were treated with hydroxyurea (1000 mg/m2/day orally divided twice per day) from June 1998 to February 2012. Nine female and 4 male, ranging in age from 32 to 83 years (median age 61.7 years), were included. Follow-up assessment included physical examination, computed tomography, and magnetic resonance imaging (MRI). Standard neuro-oncological response criteria (Macdonald criteria) were used to evaluate the follow-up MRI scans. The treatment was continued until there was objective disease progression or onset of unmanageable toxicity. RESULTS: Ten of the 13 patients (76.9%) showed stable disease after treatment, with time to progression ranging from 8 to 128 months (median 72.4 months; 6 patients still accruing time). However, there was no complete response or partial response in any patients. Three patients had progressive disease after 88, 89, 36 months, respectively. There was no severe (Grade III-IV) blood systemic disorders and no episodes of non-hematological side effects. CONCLUSION: This study showed that hydroxyurea is a modestly active agent against recurrent meningiomas and can induce long-term stabilization of disease in some patients. We think that hydroxyurea treatment is well tolerated and convenient, and could be considered as an alternative treatment option in patients with recurrent meningiomas prior to reoperation or radiotherapy.
Apoptosis ; Disease Progression ; Female ; Follow-Up Studies ; Humans ; Hydroxyurea ; Magnetic Resonance Imaging ; Male ; Meningioma ; Physical Examination ; Recurrence ; Reoperation ; Ribonucleotide Reductases

BACKGROUNDThe formation and growth of tumors are related to the synthesis of the DNA. The enzyme ribonucleotide reductase (RR) is an enzyme that regulates the total rate of DNA synthesis and thus plays a pivotal role in cell growth. Catalytic subunit M2 (RRM2) is the main unit modulating the ribonucleotide reductase enzymatic activity. This study aimed to investigate the expression of RRM2 mRNA and protein in patients with ovarian cancer and its relevance to diagnosis and clinical outcome of the patients.

METHODSRRM2 mRNA levels and protein expression were detected in 98 ovarian specimens with immunohistochemistry and real-time quantitative polymerase chain reaction (PCR). Expression of the RRM2 protein and correlation of the RRM2 gene expression with clinical pathological features were analyzed. The Kaplan-Meier test was used for evaluating RRM2 expression and time to progression and survival. The Cox proportional model was used to analyze the risk factors in prognosis of patients.

RESULTSPositive RRM2 immunostaining was found in 43 of 62 (69.4%) patients with epithelial ovarian cancer, 10 of 15 (66.7%) patients with borderline neoplasm, 4 of 15 (26.7%) patients with benign growths, and none of the normal group. The RRM2 mRNA levels were significantly over expressed in epithelial ovarian cancer (1.722 ± 0.639) and borderline ovarian neoplasms (1.365 ± 0.615), compared to the normal group (0.678 ± 0.446) and benign group (0.828 ± 0.545). Patients with ovarian caner in clinical FIGO-stages III-IV presented higher RRM2 gene expression than those in clinical FIGO-stages I-II. Furthermore, the survival of patients with low RRM2 mRNA level was significantly better than patients with high levels (P < 0.05). By Cox proportional risk model analysis, the risk of mortality of patients with high level expression of RRM2 mRNA was 2.553 times greater than those with low expression.

CONCLUSIONRRM2 expression closely correlates with the development of ovarian tumor and may serve as a novel predictive marker for diagnosis and prognosis of the disease.

Adolescent ; Adult ; Aged ; Female ; Humans ; Immunohistochemistry ; Middle Aged ; Ovarian Neoplasms ; enzymology ; genetics ; Real-Time Polymerase Chain Reaction ; Ribonucleoside Diphosphate Reductase ; genetics ; metabolism ; Young Adult

The Ribonucleotide reductases (RNR) are essential enzymes that catalyze the conversion of nucleotides to deoxynucleotides in DNA replication and repair in all living organisms. The RNRs operate by a free radical mechanism but differ in the composition of subunit, cofactor required and regulation by allostery. Based on these differences the RNRs are classified into three classes-class I, class II and class III which depend on oxygen, adenosylcobalamin and S-adenosylmethionine with an iron sulfur cluster respectively for radical generation. In this article thirty seven sequences belonging to each of the three classes of RNR were analyzed by using various tools of bioinformatics. Phylogenetic analysis, dot-plot comparisons and motif analysis was done to identify a number of differences in the three classes of RNRs. In this research article, we have attempted to decipher evolutionary relationship between the three classes of RNR by using bioinformatics approach.
Cobamides ; Computational Biology ; DNA Replication ; Iron ; Nucleotides ; Oxygen ; Ribonucleotide Reductases ; S-Adenosylmethionine ; Sulfur