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1.  RAS Transformation Requires CUX1-Dependent Repair of Oxidative DNA Damage 
PLoS Biology  2014;12(3):e1001807.
The base excision repair (BER) that repairs oxidative damage is upregulated as an adaptive response in maintaining tumorigenesis of RAS-transformed cancer cells.
The Cut homeobox 1 (CUX1) gene is a target of loss-of-heterozygosity in many cancers, yet elevated CUX1 expression is frequently observed and is associated with shorter disease-free survival. The dual role of CUX1 in cancer is illustrated by the fact that most cell lines with CUX1 LOH display amplification of the remaining allele, suggesting that decreased CUX1 expression facilitates tumor development while increased CUX1 expression is needed in tumorigenic cells. Indeed, CUX1 was found in a genome-wide RNAi screen to identify synthetic lethal interactions with oncogenic RAS. Here we show that CUX1 functions in base excision repair as an ancillary factor for the 8-oxoG-DNA glycosylase, OGG1. Single cell gel electrophoresis (comet assay) reveals that Cux1+/− MEFs are haploinsufficient for the repair of oxidative DNA damage, whereas elevated CUX1 levels accelerate DNA repair. In vitro base excision repair assays with purified components demonstrate that CUX1 directly stimulates OGG1's enzymatic activity. Elevated reactive oxygen species (ROS) levels in cells with sustained RAS pathway activation can cause cellular senescence. We show that elevated expression of either CUX1 or OGG1 prevents RAS-induced senescence in primary cells, and that CUX1 knockdown is synthetic lethal with oncogenic RAS in human cancer cells. Elevated CUX1 expression in a transgenic mouse model enables the emergence of mammary tumors with spontaneous activating Kras mutations. We confirmed cooperation between KrasG12V and CUX1 in a lung tumor model. Cancer cells can overcome the antiproliferative effects of excessive DNA damage by inactivating a DNA damage response pathway such as ATM or p53 signaling. Our findings reveal an alternate mechanism to allow sustained proliferation in RAS-transformed cells through increased DNA base excision repair capability. The heightened dependency of RAS-transformed cells on base excision repair may provide a therapeutic window that could be exploited with drugs that specifically target this pathway.
Author Summary
In the context of tumor development and progression, mutations are believed to accumulate owing to compromised DNA repair. Such mutations promote oncogenic growth. Yet cancer cells also need to sustain a certain level of DNA repair in order to replicate their DNA and successfully proliferate. Here we show that cancer cells that harbor an activated RAS oncogene exhibit heightened DNA repair capability, specifically in the base excision repair (BER) pathway that repairs oxidative DNA damage. RAS oncogenes alone do not transform primary cells but rather cause their senescence—that is, they stop dividing. As such, cellular senescence in this context is proposed to function as a tumor-suppressive mechanism. We show that CUX1, a protein that accelerates oxidative DNA damage repair, prevents cells from senescing and enables proliferation in the presence of a RAS oncogene. Consistent with this, RAS-induced senescence is also prevented by ectopic expression of OGG1, the DNA glycosylase that removes 8-oxoguanine, the most abundant oxidized base. Strikingly, CUX1 expression in transgenic mice enables the emergence of tumors with spontaneous activating Kras mutations. Conversely, knockdown of CUX1 is synthetic lethal for RAS-transformed cells, thereby revealing a potential Achilles' heel of these cancer cells. Overall, the work provides insight into understanding the role of DNA repair in cancer progression, showing that while DNA damage-induced mutations promote tumorigenesis, sustained RAS-dependent tumorigenesis requires suppression of DNA damage. The heightened dependency of RAS-transformed cells on base excision repair may provide a therapeutic window that could be exploited with drugs that specifically target this pathway.
doi:10.1371/journal.pbio.1001807
PMCID: PMC3949673  PMID: 24618719
2.  Effects of Low-Carbohydrate Diets Versus Low-Fat Diets on Metabolic Risk Factors: A Meta-Analysis of Randomized Controlled Clinical Trials 
American Journal of Epidemiology  2012;176(Suppl 7):S44-S54.
The effects of low-carbohydrate diets (≤45% of energy from carbohydrates) versus low-fat diets (≤30% of energy from fat) on metabolic risk factors were compared in a meta-analysis of randomized controlled trials. Twenty-three trials from multiple countries with a total of 2,788 participants met the predetermined eligibility criteria (from January 1, 1966 to June 20, 2011) and were included in the analyses. Data abstraction was conducted in duplicate by independent investigators. Both low-carbohydrate and low-fat diets lowered weight and improved metabolic risk factors. Compared with participants on low-fat diets, persons on low-carbohydrate diets experienced a slightly but statistically significantly lower reduction in total cholesterol (2.7 mg/dL; 95% confidence interval: 0.8, 4.6), and low density lipoprotein cholesterol (3.7 mg/dL; 95% confidence interval: 1.0, 6.4), but a greater increase in high density lipoprotein cholesterol (3.3 mg/dL; 95% confidence interval: 1.9, 4.7) and a greater decrease in triglycerides (−14.0 mg/dL; 95% confidence interval: −19.4, −8.7). Reductions in body weight, waist circumference and other metabolic risk factors were not significantly different between the 2 diets. These findings suggest that low-carbohydrate diets are at least as effective as low-fat diets at reducing weight and improving metabolic risk factors. Low-carbohydrate diets could be recommended to obese persons with abnormal metabolic risk factors for the purpose of weight loss. Studies demonstrating long-term effects of low-carbohydrate diets on cardiovascular events were warranted.
doi:10.1093/aje/kws264
PMCID: PMC3530364  PMID: 23035144
carbohydrate-restricted diet; fat-restricted diet; meta-analysis; metabolic syndrome; obesity
3.  Low Birth Weight Is Associated With Higher Blood Pressure Variability From Childhood to Young Adulthood 
American Journal of Epidemiology  2012;176(Suppl 7):S99-S105.
The association between birth weight and long-term within-individual variability of blood pressure (BP) was examined in a longitudinal cohort of 1,454 adults (939 whites and 515 blacks; adulthood age = 19–50 years) enrolled in the Bogalusa Heart Study in Bogalusa, Louisiana, in 1973–2010. BP variability was depicted as standard deviation, coefficient of variation, and deviation from age-predicted values using 6–15 serial BP measurements from childhood to adulthood over an average of 25.7 years. Birth weight was significantly and negatively associated with adulthood BP levels, long-term BP levels, and rate of change. Importantly, low birth weight was significantly associated with increased BP variability in terms of standard deviation, coefficient of variation, and deviation. As evaluated using the regression coefficients, a 1-kg lower birth weight was associated with increases in systolic BP variability measures (−0.38 mm Hg, P = 0.04 for standard deviation; −0.004 mm Hg, P = 0.01 for coefficient of variation; and −0.16 mm Hg, P = 0.04 for deviation) after adjustment for race, age, sex, mean BP levels, and gestational age; similar trends in the associations were noted for diastolic BP variability measures. In conclusion, these findings suggest that birth weight affects not only BP levels but also the magnitude of within-individual BP fluctuations over time through fetal programming in BP regulation mechanisms.
doi:10.1093/aje/kws298
PMCID: PMC3530367  PMID: 23035149
birth weight; black-white; blood pressure variability; childhood
4.  Diabetes education improves depressive state in newly diagnosed patients with type 2 diabetes 
Pakistan Journal of Medical Sciences  2013;29(5):1147-1152.
Objectives: The prevalence of depression is relatively high in individuals with diabetes. However, screening and monitoring of depressive state in patients with diabetes is still neglected in developing countries and the treatment of diabetes-related depression is rarely performed in these countries. In this study, our aim was to study the role of diabetes education in the improvement of depressive state in newly diagnosed patients with type 2 diabetes.
Methods: The Dutch version of the center for epidemiological studies depression scale (CES-D scale) and the problem areas in diabetes (PAID) questionnaire were used to assess depression and diabetes-specific emotional distress in 1200 newly diagnosed male adult patients with type 2 diabetes before and after a two-week diabetes education by professionally trained nurses. Pearson correlation and regression analysis were used to analyze the factors related to depression in patients with type 2 diabetes.
Results: The incidence of depression in newly diagnosed patients with type 2 diabetes was 28%, and the rate of diabetes-specific emotional distress was 65.5%. High education levels, low income were correlated to depression in individuals with diabetes. After two weeks of diabetes education, the incidence of depression and diabetes-specific emotional distress decreased significantly to 20.5% (P < 0.05) and 11% (P < 0.001), respectively.
Conclusions: The incidence of depression, especially diabetes-specific emotional distress, was relatively high in newly diagnosed patients with type 2 diabetes. The depression state could be improved by diabetes education.
PMCID: PMC3858924  PMID: 24353709
Incidence of depression; emotional distress; Type 2 diabetes; diabetes education
5.  The Joint Effect of hOGG1, APE1, and ADPRT Polymorphisms and Cooking Oil Fumes on the Risk of Lung Adenocarcinoma in Chinese Non-Smoking Females 
PLoS ONE  2013;8(8):e71157.
Background
The human 8-oxoguanine DNA glycosylase 1 (hOGG1), apurinic/apyrimidinic endonuclease 1 (APE1), and adenosine diphosphate ribosyl transferase (ADPRT) genes play an important role in the DNA base excision repair pathway. Single nucleotide polymorphisms (SNPs) in critical genes are suspected to be associated with the risk of lung cancer. This study aimed to identify the association between the polymorphisms of hOGG1 Ser326Cys, APE1 Asp148Glu, and ADPRT Val762Ala, and the risk of lung adenocarcinoma in the non-smoking female population, and investigated the interaction between genetic polymorphisms and environmental exposure in lung adenocarcinoma.
Methods
We performed a hospital-based case-control study, including 410 lung adenocarcinoma patients and 410 cancer-free hospital control subjects who were matched for age. Each case and control was interviewed to collect information by well-trained interviewers. A total of 10 ml of venous blood was collected for genotype testing. Three polymorphisms were analyzed by the polymerase chain reaction-restriction fragment length polymorphism technique.
Results
We found that individuals who were homozygous for the variant hOGG1 326Cys/Cys showed a significantly increased risk of lung adenocarcinoma (OR = 1.54; 95% CI: 1.01–2.36; P = 0.045). When the combined effect of variant alleles was analyzed, we found an increased OR of 1.89 (95% CI: 1.24–2.88, P = 0.003) for lung adenocarcinoma individuals with more than one homozygous variant allele. In stratified analyses, we found that the OR for the gene-environment interaction between Ser/Cys and Cys/Cys genotypes of hOGG1 codon 326 and cooking oil fumes for the risk of lung adenocarcinoma was 1.37 (95% CI: 0.77–2.44; P = 0.279) and 2.79 (95% CI: 1.50–5.18; P = 0.001), respectively.
Conclusions
The hOGG1 Ser326Cys polymorphism might be associated with the risk of lung adenocarcinoma in Chinese non-smoking females. Furthermore, there is a significant gene-environment association between cooking oil fumes and hOGG1 326 Cys/Cys genotype in lung adenocarcinoma among female non-smokers.
doi:10.1371/journal.pone.0071157
PMCID: PMC3741325  PMID: 23951099
6.  Identification of Key Drought Stress-Related Genes in the Hyacinth Bean 
PLoS ONE  2013;8(3):e58108.
Hyacinth bean (Lablab purpureus [Linn.] Sweet) possesses excellent characteristics for field production, but the response of this plant to drought stress has not been described at the molecular level. Suppression subtraction hybridization (SSH) is an effective way to exploit key factors for plant responses to drought stress that are involved in transcriptional and metabolic activities. In this study, forward and reverse SSH libraries were generated from root tissues of the drought-tolerant hyacinth bean genotype MEIDOU 2012 under water–stress conditions. A total of 1,287 unigenes (94 contigs and 1,193 singletons) were derived from sequence alignment and cluster assembly of 1400 ESTs, and 80.6% of those hit against NCBI non-redundant (nr) database with E value <1E−06. BLASTX analysis revealed that the majority top matches were proteins form Glycine max (L.) Merrill. (61.5%). According to a gene ontology (GO) functional classification, 816 functionally annotated unigenes were assigned to the biological process category (74.1%), and 83.9% of them classified into molecular function and 69.2% involved in cellular component. A total of 168 sequences were further annotated with 207 Enzyme Commission (EC) codes and mapped to 83 different KEGG pathways. Seventeen functionally relevant genes were found to be overrepresented under drought stress using enrichment analysis. Differential expression of unigenes were confirmed by quantitative real-time PCR assays, and their transcript profiles generally divided into three patterns, depending on the expression peaked levels after 6, 8 or 10 days dehydration, which indicated that these genes are functionally associated in the drought-stress response.
doi:10.1371/journal.pone.0058108
PMCID: PMC3589356  PMID: 23472143
7.  Monitoring Response and Resistance to the Novel Arsenical Darinaparsin in an AML Patient 
Acute myeloid leukemia (AML) with inversion of chromosome 3 is characterized by overexpression of EVI1 and carries a dismal prognosis. Arsenic-containing compounds have been described to be efficacious in malignancies overexpressing EVI1. Here, we describe a case of AML with inv(3)(q21q26.2) treated with the organic arsenical darinaparsin. Using a “personalized medicine approach,” two different arsenicals were screened for anti-leukemic effect against the patient’s cells ex vivo. The most promising compound, darinaparsin, was selected for in vivo treatment. Clinical effect was almost immediate, with a normalization of temperature, a stabilization of white blood cell (WBC) counts and an increased quality of life. Longitudinal monitoring of patient response and resistance incorporating significant correlative studies on patient-derived blood samples over the two cycles of darinaparsin given to this patient allowed us to evaluate potential mechanisms of response and resistance. The anti-leukemic effects of darinaparsin correlated with inhibition of the alternative NF-κB pathway and production of the inflammatory cytokine IL-8. Emergence of resistance was suspected during treatment cycle 2 and supported by xenograft studies in nude mice. Darinaparsin resistance correlated with an attenuation of the effect of treatment on the alternative NF-κB pathway. The results from this patient indicate that darinaparsin may be a good treatment option for inv(3) AML and that inhibition of the alternative NF-κB pathway may be predictive of response. Longitudinal monitoring of disease response as well as several correlative parameters allowed for the generation of novel correlations and predictors of response to experimental therapy in a heavily pretreated patient.
doi:10.3389/fphar.2013.00009
PMCID: PMC3570070  PMID: 23408639
acute myeloid leukemia; inv(3)(q21q26.2); darinaparsin; experimental treatment; resistance; personalized medicine
8.  Protein phosphatase PP6 is required for homology-directed repair of DNA double-strand breaks 
Cell Cycle  2011;10(9):1411-1419.
DNA double-strand breaks (DSBs) are among the most lethal lesions associated with genome stability, which, when destabilized, predisposes organs to cancers. DSBs are primarily fixed either with little fidelity by non-homologous end joining (NHEJ) repair or with high fidelity by homology-directed repair (HDR). The phosphorylated form of H2AX on serine 139 (γ-H2AX) is a marker of DSBs. In this study, we explored if the protein phosphatase PP6 is involved in DSB repair by depletion of its expression in human cancer cell lines, and determined PP6 expression in human breast cancer tissues by immunohistochemistry staining. We found that bacterially produced PP6c (the catalytic subunit of PP6)-containing heterotrimeric combinations exhibit phosphatase activity against γ-H2AX in the in vitro phosphatase assays. Depletion of PP6c or PP6R2 led to persistent high levels of γ-H2AX after DNA damage and a defective HDR. Chromatin immunoprecipitation assays demonstrated that PP6c was recruited to the region adjacent to the DSB sites. Expression of PP6c, PP6R2 and PP6R3 in human breast tumors was significantly lower than those in benign breast diseases. Taken together, our results suggest that γ-H2AX is a physiological substrate of PP6 and PP6 is required for HDR and its expression may harbor a protective role during the development of breast cancer.
doi:10.4161/cc.10.9.15479
PMCID: PMC3117043  PMID: 21451261
protein phosphatase; PP6; γ-H2AX; DNA double-strand break; homology-directed repair
9.  Synergistic antitumor efficacy by combining adriamycin with recombinant human endostatin in an osteosarcoma model 
Oncology Letters  2011;2(5):773-778.
In the last 15 years, chemotherapy-based therapeutic regimens for the treatment of osteosarcoma have failed to demonstrate improved survival rates. Novel approaches, including targeted therapy and antiangiogenic therapy, may provide new methods for the treatment of osteosarcoma, one of the most deadly malignant diseases. In the present study, the therapeutic efficacy of an endogenous angiogenesis inhibitor, endostatin, was tested in combination with the chemotherapeutic agent, adriamycin. BALB/c mice, aged 4-6 weeks were fed animal chow and had access to water ad libitum. The mice were divided into groups and injected with tumor cells. Immunohistochemical staining was performed to identify the microvessel density. The TUNEL technique was also used to determine the apoptotic index. The combination of endostatin and adriamycin produced marked synergistic antitumor activity in a mouse osteosarcoma model. These findings provide new guidelines for designing future clinical trials and for the application of currently available clinical drugs (endostatin has been approved for clinical use) in the treatment of osteosarcoma.
doi:10.3892/ol.2011.334
PMCID: PMC3408098  PMID: 22866125
10.  Breast Cancer Subtypes and Survival in Chinese Women with Operable Primary Breast Cancer 
Objective
To investigate the associations between the different breast cancer subtypes and survival in Chinese women with operable primary breast cancer.
Methods
A total of 1538 Chinese women with operable primary breast cancer were analyzed in this study, the median follow-up was 77 months. Estrogen receptor (ER), progesterone receptor (PR), and HER2 status were available for these patients.
Results
Luminal A (ER+ and/or PR+, HER2-) had a favorable disease-free survival (DFS) and overall survival (OS) compared with other subtypes in the entire cohort. Using the luminal A as a reference, among the patients with lymph node positive disease, HER2+ (ER-, PR-, HER2+) had the worst DFS (hazard ratio, HR=1.80, 95% CI 1.11 to 2.91, P=0.017) and luminal B (ER+ and/or PR+, HER2+) had the worst OS (HR=2.27, 95% CI 1.50 to 3.45, P<0.001); among the patients with lymph node negative disease, triple-negative (ER-, PR-, HER2-) had the worst DFS (HR=2.21, 95% CI 1.43 to 3.41, P<0.001), whereas no significant difference in DFS between HER2+ and luminal B or luminal A was observed.
Conclusion
As compared with luminal A, luminal B and HER2+ have the worst survival in patients with lymph node positive disease, but this is not the case in patients with lymph node negative disease; triple-negative subtype has a worse survival in both lymph node positive and lymph node negative patients.
doi:10.1007/s11670-011-0134-z
PMCID: PMC3587543  PMID: 23482992
Breast cancer; Subtypes; Disease-free survival; Overall survival

Results 1-10 (10)