Knockdown of RMI1 impairs DNA repair under DNA replication stress.

RMI1 (RecQ-mediated genome instability protein 1) forms a conserved BTR complex with BLM, Topo IIIα, and RMI2, and its absence causes genome instability. It has been revealed that RMI1 localizes to nuclear foci with BLM and Topo IIIα in response to replication stress, and that RMI1 functions downstream of BLM in promoting replication elongation. However, the precise functions of RMI1 during replication stress are not completely understood. Here we report that RMI1 knockdown cells are hypersensitive to hydroxyurea (HU). Using comet assay, we show that RMI1 knockdown cells exhibit accumulation of broken DNAs after being released from HU treatment. Moreover, we demonstrate that RMI1 facilitates the recovery from activated checkpoint and resuming the cell cycle after replicative stress. Surprisingly, loss of RMI1 results in a failure of RAD51 loading onto DNA damage sites. These findings reveal the importance of RMI1 in response to replication stress, which could explain the molecular basis for its function in maintaining genome integrity.

Accumulation and Phosphorylation of RecQ-Mediated Genome Instability Protein 1 (RMI1) at Serine 284 and Serine 292 during Mitosis.

Chromosome instability usually leads to tumorigenesis. Bloom syndrome (BS) is a genetic disease associated with chromosome instability. The BS gene product, BLM, has been reported to function in the spindle assembly checkpoint (SAC) to prevent chromosome instability. BTR complex, composed of BLM, topoisomerase IIIα (Topo IIIα), RMI1 (RecQ-mediated genome instability protein 1, BLAP75) and RMI2 (RecQ-mediated genome instability protein 2, BLAP18), is crucial for maintaining genome stability. Recent work has demonstrated that RMI2 also plays critical role in SAC. However, little is know about RMI1 regulation during the cell cycle. Here we present that RMI1 protein level does not change through G1, S and G2 phases, but significantly increases in M phase. Moreover, phosphorylation of RMI1 occurs in mitosis. Upon microtubule-disturbing agent, RMI1 is phosphorylated primarily at the sites of Serine 284 and Serine 292, which does not interfere with the formation of BTR complex. Additionally, this phosphorylation is partially reversed by roscovitine treatment, implying cycling-dependent kinase 1 (CDK1) might be one of the upstream kinases.

Characterization, antioxidant and antitumor activities of phenolic compounds from Amomum villosum Lour.

Amomum villosum Lour. (A. villosum), known as Sharen in China, is widely used for culinary and medicinal purposes due to containing a diverse set of bioactive compounds. In this study, the optimum ethanol extraction process was optimized and the composition and biological activities (antioxidant and antitumor) of five different fractions (dichloromethane, petroleum ether, ethyl acetate, n-butanol and H2O) extracted from the ethanol extract of A. villosum were investigated. The results showed that the optimal extraction conditions were extraction temperature 80°C, extraction time 120 min, ethanol concentration 40% and solid-liquid ratio 1:25 g/mL. Moreover, 35 bioactive compounds were successfully identified by UPLC-ESI-QTOF-MS/MS from five factions for the first time, including 12 phenolic acids and derivatives, 2 organic acids, 12 flavonoids and derivatives, 2 oxylipins and 7 proanthocyanidins. Among them, ethyl acetate fraction (Fr-EtOAc) exhibited the highest content of total phenolic (374.01 mg GAE/g DW) and flavonoid (93.11 mg RE/g DW), where vanillic acid, catechin, epicatechin and protocatechuic acid were the predominant phenolic compounds that accounting for 81.65% of the quantified bioactive compounds. In addition, Fr-EtOAc demonstrated excellent total antioxidant activity (IC50 of DPPH and ABTS assays were 0.23, 0.08 mg/mL, respectively, and FRAP assay was 322.91 mg VCE/100 g DW) and antitumor activity (1,000 µg/mL, 79.04% inhibition rate). The results could provide guidance for the industrial production and application of A. villosum.

Evaluation of the comet assay for assessing the dose-response relationship of DNA damage induced by ionizing radiation.

Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001). A time-response relationship was also found within 72 h after irradiation (p < 0.001). The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined.

Radiation-sensitising effects of antennapedia proteins (ANTP)-SmacN7 on tumour cells.

The objective of this study was to investigate the underlying mechanisms behind the radiation-sensitising effects of the antennapedia proteins (ANTP)-smacN7 fusion protein on tumour cells. ANTP-SmacN7 fusion proteins were synthesised, and the ability of this fusion protein to penetrate cells was observed. Effects of radiation on the expression of X-linked inhibitor of apoptosis protein (XIAP) were detected by western blotting. The radiation-sensitising effects of ANTP-SmacN7 fusion proteins were observed by a clonogenic assay. The effects of drugs and radiation on tumour cell apoptosis were determined using Annexin V/FITC double staining. Changes in caspase-8, caspase-9 and caspase-3 were detected by western blot before and after ANTP-SmacN7 inhibition of XIAP. The ANTP-SmacN7 fusion protein could enter and accumulate in cells; in vitro XIAP expression of radiation-induced tumour cells was negatively correlated with tumour radiosensitivity. The ANTP-SmacN7 fusion protein promoted tumour cell apoptosis through the activation of caspase3. ANTP-SmacN7 fusion protein may reduce tumour cell radioresistance by inducing caspase3 activation.

Cytogenetic abnormalities in lymphocytes from victims exposed to cobalt-60 radiation.

The present study investigates cytogenetic damage in lymphocytes, derived from three victims who were unfortunately exposed to cobalt-60 (60Co) radiation (the 1999 accident occurred in a village in China's Henan province). Case A of the three victims was exposed to a higher dose of 60Co radiation than Cases B and C. The chromosomal aberrations, cytokinesis-block micronucleus (CBMN, the CBMN assay), and DNA double-strand breaks (DSBs, the comet assay) examined in this study are biomarkers for cytogenetic abnormalities. After the lymphocytes collected from the victims were cultured, the frequencies of dicentric chromosomes and rings (dic + r) and CBMN in the first mitotic division detected in the lymphocytes of Case A were found to be substantially higher than in Cases B and C. Similarly, the DNA-DSB level found in the peripheral blood collected from Case A was much higher than those of Cases B and C. These results suggest that an acutely enhanced induction of the 60Co-induced cytogenetic abnormality frequency in humans depends on the dose of 60Co radiation. This finding is supported by the data obtained using practical techniques to evaluate early lymphoid-tissue abnormalities induced after exposure to acute radiation.

Expression patterns, activities and carbohydrate-metabolizing regulation of sucrose phosphate synthase, sucrose synthase and neutral invertase in pineapple fruit during development and ripening.

Differences in carbohydrate contents and metabolizing-enzyme activities were monitored in apical, medial, basal and core sections of pineapple (Ananas comosus cv. Comte de paris) during fruit development and ripening. Fructose and glucose of various sections in nearly equal amounts were the predominant sugars in the fruitlets, and had obvious differences until the fruit matured. The large rise of sucrose/hexose was accompanied by dramatic changes in sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) activities. By contrast, neutral invertase (NI) activity may provide a mechanism to increase fruit sink strength by increasing hexose concentrations. Furthermore, two cDNAs of Ac-sps (accession no. GQ996582) and Ac-ni (accession no. GQ996581) were first isolated from pineapple fruits utilizing conserved amino-acid sequences. Homology alignment reveals that the amino acid sequences contain some conserved function domains. Transcription expression analysis of Ac-sps, Ac-susy and Ac-ni also indicated distinct patterns related to sugar accumulation and composition of pineapple fruits. It suggests that differential expressions of multiple gene families are necessary for sugar metabolism in various parts and developmental stages of pineapple fruit. A cycle of sucrose breakdown in the cytosol of sink tissues could be mediated through both Ac-SuSy and Ac-NI, and Ac-NI could be involved in regulating crucial steps by generating sugar signals to the cells in a temporally and spatially restricted fashion.

Identification of phenolics from miracle berry (Synsepalum dulcificum) leaf extract and its antiangiogenesis and anticancer activities.

Miracle berry is well-known for its ability to convert sour foods to sweet. In this study, the secondary metabolites of miracle berry leaves (MBL) were identified by UPLC-DAD-MS, and its antiangiogenesis and anticancer activities were evaluated by using a zebrafish model and the MCF-7 xenograft mouse model, respectively. The result showed that 18 phenolic compounds were identified in MBL extract, and dominated by the derivatives of quercetin and myricetin. The MBL extract showed low toxicity and high antiangiogenesis activity, it significantly inhibited the subintestinal vein vessels development in zebrafish at very low concentration. Furthermore, the MBL extract could promote the apoptosis of tumor cells and significantly inhibit the growth of MCF-7 xenograft tumor. In addition, the analysis of metabolites revealed that the MBL extract inhibited tumor growth by activating the metabolic pathways of unsaturated fatty acids and purines. Overall, this study suggests that MBL extract can be used as a natural anticancer adjuvant in the fields of functional foods.

Preparation of ethylenediamine-modified pectin/alginate/Fe3O4 microsphere and its efficient Pb2+ adsorption properties.

As a common macromolecular carbohydrate, pectin has a strong affinity for Pb2+. An ethylenediamine modified pectin (EP48) with 48 % of amidation was prepared and exhibited great removal efficiency towards Pb2+ in our previous study. However, the EP48 has drawbacks in adsorption including low mechanical strength and difficulty in separation. In this study, EP48 was compounded with sodium alginate (Alg) and Fe3O4 to synthesize EP48/Alg/Fe3O4 microsphere. The physicochemical properties and Pb2+ adsorption characteristics of microsphere were analyzed. It was found that the microsphere exhibited good thermal stability, mechanical strength, porous structure, as well as acid tolerance. The pseudo-second-order model well described the kinetics of adsorption process, indicating the chemical adsorption is dominant. The Langmuir model fitted the experimental data well, and the maximum adsorption capacity reached 175.19 mg/g. Adsorption-desorption experiments showed that the removal rate of the microsphere maintained over 98.9 % after 10 cycles. The X-ray photoelectron spectroscopy (XPS) analyses revealed that the potential adsorption mechanism included ion-exchange and chelation. The above results suggested its potential use for the removal of Pb2+ from wastewater.

A comprehensive study of raw and roasted macadamia nuts: Lipid profile, physicochemical, nutritional, and sensory properties.

Macadamia nuts have high nutritional value and positive health attributes. Changes to the composition and availability of these compounds during roasting contribute to product quality. In this study, changes to the chemical composition of lipids (fatty acids, triglycerides, and free fatty acids) and other phytochemicals were analyzed, and a sensory evaluation was carried out of two major varieties of macadamia nuts planted in China, after roasting. Only small changes in fatty acid (FA) content and a slight decrease in total triglycerides (TAGs) were observed after roasting. The free fatty acid (FFA) content and the peroxide value were increased by roasting. The total available polyphenol content increased by 25.6% and the oxidative stability index of kernels increased by 21.6%. The sensory scores for taste and aroma were doubled by roasting. Overall, the sensory, nutritional quality, and oxidative stability of roasted macadamia nuts were greatly improved, compared with raw nuts.

ShRNA-mediated Ku80 gene silencing inhibits cell proliferation and sensitizes to gamma-radiation and mitomycin C-induced apoptosis in esophageal squamous cell carcinoma lines.

To investigate the effects of Ku80 depletion on cell growth and sensitization to gamma-radiation and MMC-induced apoptosis in esophageal squamous cell carcinoma lines. Six human carcinoma cell lines (LNcaP, K562, MDA-MB-231, MCF-7, EC9706, and K150) and normal HEK293 cell line were examined for basal levels of Ku80 protein by western blotting analysis. The suppression of Ku80 expression was performed using vector-based shRNA in EC9706 cells. Cell proliferation was determined with MTT assay and colony formation assay and tumorigenicity in a xenograft model in vitro and in vivo. Sensitivity of EC9706 cells treated with shRNA vector to gamma-radiation and MMC was determined with colony formation assay and MTT assay. The cell cycle distribution was determined by Flow cytometry. Apoptosis induced by gamma-radiation and MMC was analyzed using GENMED-TUNEL FACS kit. Ku80 showed higher basal levels in six carcinoma cell lines than in HEK293. The suppression of Ku80 expression decreased cellular proliferation, colony formation and inhibited tumorigenicity in a xenograft model. Furthermore, it sensitized apoptosis of the cancer cells induced by gamma-radiation and MMC. Ku80 plays an important role not only in tumorigenesis but also in radiation resistance and chemotherapy resistance in esophageal cancer cells. Hence Ku80 may serve as a promising therapeutic target, particularly for recurrent esophageal tumors.

[Study on safety and efficacy of concentrated potassium chloride infusions in critically ill patients with hypokalemia].

OBJECTIVE: To explore the safety and clinical efficacy of intravenous infusion of concentrated potassium chloride using micro-pumps in critically ill patients with hypokalemia. METHODS: One hundred and twenty-eight critically ill patients with hypokalemia, the endogenous creatinine clearance rate over 0.5 ml/second and the urine output over 50 ml/hour were randomly divided into the therapy group (n=64) and the control group (n=64). Patients in therapy group received 1,208 mmol/L (9%) KCl, while those in the control group received 201 mmol/L (1.5%) potassium chloride, intravenously with the aid of a micro-pump, with hourly equal quantity of KCl in both groups. Patients in both groups were monitored strictly, and the potassium infusion was stopped whenever the serum potassium exceeded or equal to 3.5 mmol/L. RESULTS: It took (15.55+/-3.22) hours and (14.18+/-4.93) hours for the therapy group and the control group to correct the hypokalemia respectively, and there was no significant difference (P>0.05). Potassium infusion brought larger amount of fluid in the control group than the therapy group [(124.36+/-25.79) ml vs. (680.83+/-236.70) ml, P<0.01]. All patients tolerated the infusion without evidence of hemodynamic change, hyperkalemia or acute heart dysfunction. For all the patients, renal function did not throw significant influence on the potassium infusion time. An inverse correlation was observed between preinfusion potassium concentration and the quantity of potassium infused (r= -0.259, P<0.01). CONCLUSION: Under meticulous monitoring, it is safe and effective to infuse concentrated potassium for the critically ill patients with hypokalemia. This strategy can also be followed in patients with mild renal dysfunction but without oliguria or anuria under careful monitoring.

Methotrexate-mediated inhibition of RAD51 expression and homologous recombination in cancer cells.

BACKGROUND: Methotrexate is an inhibitor of folic acid metabolism. Homologous recombination is one of the most important ways to repair double-stranded breaks in DNA and influence the radio- and chemosensitivity of tumor cells. But the relationship between methotrexate and homologous recombination repair has not been elucidated. METHODS: Induction of double-strand breaks by methotrexate in HOS cells is assessed by the neutral comet assay. Inhibition of subnuclear repair foci by methotrexate is measured by immunofluorescence. Western blot and quantitative real-time PCR are conducted to detect whether methotrexate affects the expression level of genes involved in homologous recombination. In addition, we used a pCMV3xnls-I-SceI construct to determine whether methotrexate directly inhibits the process of homologous recombinational repair in cells, and the sensitivity to methotrexate in the Ku80-deficient cells is detected using clonogenic survival assays. RESULTS: The result showed that methotrexate can regulate the repair of DNA double-strand breaks after radiation exposure, and methotrexate inhibition caused the complete inhibition of subnuclear repair foci in response to ionizing radiation. Mechanistic investigation revealed that methotrexate led to a significant reduction in the transcription of RAD51 genes. Treatment with methotrexate resulted in a decreased ability to perform homology-directed repair of I-SceI-induced chromosome breaks. In addition, enhancement of cell death was observed in Ku mutant cells compared to wild-type cells. CONCLUSIONS: These results demonstrate that methotrexate can affect homologous recombination repair of DNA double-strand breaks by controlling the expression of homologous recombination-related genes and suppressing the proper assembly of homologous recombination-directed subnuclear foci.

Knockdown of Rad51 expression induces radiation- and chemo-sensitivity in osteosarcoma cells.

Osteosarcoma is the common primary bone malignancy in children and young adults in Eastern countries. Resistance to ionizing radiation (IR) or drugs is an underlying mechanism contributing to the failure of therapy in these patients. Rad51 is the key protein of DNA homologous recombination repair. Although high expression of Rad51 is associated with enhanced resistance to DNA damage induced by chemicals and/or ionizing radiation, the relevance of Rad51 expression in osteosarcoma and its relationship with IR sensitivity and chemo-resistance is not well understood. In this study, we elucidated the possibility of using Rad51 in the treatment of human osteosarcoma in vitro. Changes in chemo- and radiation sensitivity in cultured osteosarcoma cells occurred after suppression of Rad51 expression, using a plasmid vector-mediated short hairpin RNA (shRNA) expression system. The suppression of Rad51 correlated with cell cycle arrest in the G2 phase and inhibited tumor cell proliferation. Our results suggest that Rad51 expression levels might play an important role in radiation- and chemo-sensitivity of human osteosarcoma.

Assessing validation of dual fluoroscopic image matching method for measurement of in vivo spine kinematics.

BACKGROUND: Accurate knowledge of the spinal structural functions is critical to understand the biomechanical factors that affect spinal pathology. Many studies have investigated the human vertebral motion both in vitro and in vivo. However, determination of in vivo motion of the vertebrae under physiologic loading conditions remains a challenge in biomedical engineering because of the limitations of current technology and the complicated anatomy of the spine. METHODS: For in vitro validation, a human lumbar specimen was imbedded with steel beads and moved to a known distance by an universal testing machine (UTM). The dual fluoroscopic system was used to capture the spine motion and reproduce the moving distance. For in vivo validation, a living subject moved the spine in various positions while bearing weight. The fluoroscopes were used to reproduce the in vivo spine positions 5 times. The standard deviations in translation and orientation of the five measurements were used to evaluate the repeatability of technique. The accuracy of vertebral outline matching with metallic marks matching technology was compared. RESULTS: The translation positions of the human lumbar specimen could be determined with a mean accuracy less than 0.35 mm and a mean repeatability 0.36 mm for the image matching technique. The repeatability of the method in reproducing in vivo human spine six degrees of freedom (6DOF) kinematics was less than 0.43 mm in translation and less than 0.65° in rotation. The accuracy of metallic marks and vertebral outline matching did not show significant difference. CONCLUSIONS: Combining a dual fluoroscopic and computerized tomography imaging technique was accurate and reproduceable for noninvasive measurement of spine vertebral motion. The vertebral outline matching technique could be a useful technique for matching of vertebral positions and orientations which can evaluate and improve the efficacy of the various surgical treatments.

Expression and function of miRNA in postoperative radiotherapy sensitive and resistant patients of non-small cell lung cancer.

PURPOSE: To investigate the different miRNA expression profiles of postoperative radiotherapy sensitive and resistant patients of non-small cell lung cancer, explore their potential role and find some radio-sensitivity markers. MATERIALS AND METHODS: Thirty non-small cell lung cancer patients who have been treated by postoperative radiotherapy were selected and were divided into radiotherapy sensitive group and resistant group according to overall survival and local or distant recurrence rate. Expression profile of miRNA in these two groups was detected by a microarray assay and the results were validated by quantitative RT-PCR and Northern blot. At the molecular level, the effect of one differently expressed miRNA (miR-126) on the growth and apoptosis of SK-MES-1 cells induced by irradiation was examined. RESULTS: Comparing with resistant patients, five miRNAs (miRNA-126, miRNA-let-7a, miRNA-495, miRNA-451 and miRNA-128b) were significantly upregulated and seven miRNAs (miRNA-130a, miRNA-106b, miRNA-19b, miRNA-22, miRNA-15b, miRNA-17-5p and miRNA-21) were greatly downregulated in radiotherapy sensitive group. Overexpression of miRNA-126 inhibited the growth of SK-MES-1 cells and promoted its apoptosis induced by irradiation. The expression level of p-Akt decreased in miRNA-126 overexpression group. After treating with phosphoinositidyl-3 kinase (PI3K) constitutively activator (IGF-1) and inhibitor (LY294002), miRNA-126 overexpression had no significant effects on the apoptosis of SK-MES-1 cells. CONCLUSION: We found 12 differently expressed miRNAs in the radiotherapy sensitive and resistant non-small cell lung cancer samples. Moreover, our results showed miRNA-126 promoted non-small cell lung cancer cells apoptosis induced by irradiation through the PI3K-Akt pathway.

Expression of miRNA-130a in nonsmall cell lung cancer.

MicroRNAs are short regulatory RNAs that negatively modulate gene expression at the posttranscriptional level and are deeply involved in the pathogenesis of several types of cancer. The miRNA-130a has been shown to play a role in antagonizing the inhibitory effects of GAX on endothelial cell proliferation, migration and tube formation, and antagonizing the inhibitory effects of HoxA5 on tube formation in vitro. Here the authors show, for the first time, that miRNA-130a expression is increased in nonsmall cell lung cancer (NSCLC) tissues. Statistical analysis showed that overexpression of miRNA-130a was strongly associated with lymph node metastasis, stage of tumor node metastasis classification and poor prognosis. Moreover, there was a significant difference in miRNA-130a expression levels between smoking and nonsmoking patients. Multivariate Cox regression analysis showed that miRNA-130a was an independent prognostic factor for patients with NSCLC. Together, these data suggest that miRNA-130a may comprise a potential novel prognostic marker for this disease.