Factors Associated with Interest in Gene-Panel Testing and Risk Communication Preferences in Women from BRCA1/2 Negative Families.

Scientific advances have allowed the development of multiplex gene-panels to assess many genes simultaneously in women who have tested negative for BRCA1/2. We examined correlates of interest in testing for genes that confer modest and moderate breast cancer risk and risk communication preferences for women from BRCA negative families. Female first-degree relatives of breast cancer patients who tested negative for BRCA1/2 mutations (N = 149) completed a survey assessing multiplex genetic testing interest and risk communication preferences. Interest in testing was high (70 %) and even higher if results could guide risk-reducing behavior changes such as taking medications (79 %). Participants preferred to receive genomic risk communications from a variety of sources including: primary care physicians (83 %), genetic counselors (78 %), printed materials (71 %) and the web (60 %). Factors that were independently associated with testing interest were: perceived lifetime risk of developing cancer (odds ratio (OR) = 1.67: 95 % confidence interval (CI) 1.06-2.65) and high cancer worry (OR = 3.12: CI 1.28-7.60). Findings suggest that women from BRCA1/2 negative families are a unique population and may be primed for behavior change. Findings also provide guidance for clinicians who can help develop genomic risk communications, promote informed decision making and customize behavioral interventions.

Native American ancestry affects the risk for gene methylation in the lungs of Hispanic smokers from New Mexico.

RATIONALE: Gene promoter methylation detected in sputum predicts lung cancer risk in smokers. Compared with non-Hispanic whites (NHW), Hispanics have a lower age-standardized incidence for lung cancer. OBJECTIVES: This study compared the methylation prevalence in sputum of NHWs with Hispanics using the Lovelace Smokers cohort (n = 1998) and evaluated the effect of Native American ancestry (NAA) and diet on biomarkers for lung cancer risk. METHODS: Genetic ancestry was estimated using 48 ancestry markers. Diet was assessed by the Harvard University Dietary Assessment questionnaire. Methylation of 12 genes was measured in sputum using methylation-specific polymerase chain reaction. The association between NAA and risk for methylation was assessed using generalized estimating equations. The ethnic difference in the association between pack-years and risk for lung cancer was assessed in the New Mexico lung cancer study. MEASUREMENTS AND MAIN RESULTS: Overall Hispanics had a significantly increased risk for methylation across the 12 genes analyzed (odds ratio, 1.18; P = 0.007). However, the risk was reduced by 32% (P = 0.032) in Hispanics with high versus low NAA. In the New Mexico lung cancer study, Hispanic non-small cell lung cancer cases have significantly lower pack-years than NHW counterparts (P = 0.007). Furthermore, compared with NHW smokers, Hispanic smokers had a more rapidly increasing risk for lung cancer as a function of pack-years (P = 0.058). CONCLUSIONS: NAA may be an important risk modifier for methylation in Hispanic smokers. Smoking intensity may have a greater impact on risk for lung cancer in Hispanics compared with NHWs.

Characteristics of Patients With Initial Clostridioides difficile Infection (CDI) That Are Associated With Increased Risk of Multiple CDI Recurrences.

Background: Because interventions are available to prevent further recurrence in patients with recurrent Clostridioides difficile infection (rCDI), we identified predictors of multiple rCDI (mrCDI) in adults at the time of presentation with initial CDI (iCDI). Methods: iCDI was defined as a positive C difficile test in any clinical setting during January 2018-August 2019 in a person aged ≥18 years with no known prior positive test. rCDI was defined as a positive test ≥14 days from the previous positive test within 180 days after iCDI; mrCDI was defined as ≥2 rCDI. We performed multivariable logistic regression analysis. Results: Of 18 829 patients with iCDI, 882 (4.7%) had mrCDI; 437 with mrCDI and 7484 without mrCDI had full chart reviews. A higher proportion of patients with mrCDI than without mrCDI were aged ≥65 years (57.2% vs 40.7%; P < .0001) and had healthcare (59.1% vs 46.9%; P < .0001) and antibiotic (77.3% vs 67.3%; P < .0001) exposures in the 12 weeks preceding iCDI. In multivariable analysis, age ≥65 years (adjusted odds ratio [aOR], 1.91; 95% confidence interval [CI], 1.55-2.35), chronic hemodialysis (aOR, 2.28; 95% CI, 1.48-3.51), hospitalization (aOR, 1.64; 95% CI, 1.33-2.01), and nitrofurantoin use (aOR, 1.95; 95% CI, 1.18-3.23) in the 12 weeks preceding iCDI were associated with mrCDI. Conclusions: Patients with iCDI who are older, on hemodialysis, or had recent hospitalization or nitrofurantoin use had increased risk of mrCDI and may benefit from early use of adjunctive therapy to prevent mrCDI. If confirmed, these findings could aid in clinical decision making and interventional study designs.

Carbapenem-resistant Acinetobacter baumannii complex in the United States-An epidemiological and molecular description of isolates collected through the Emerging Infections Program, 2019.

BACKGROUND: Understanding the epidemiology of carbapenem-resistant A. baumannii complex (CRAB) and the patients impacted is an important step toward informing better infection prevention and control practices and improving public health response. METHODS: Active, population-based surveillance was conducted for CRAB in 9 U.S. sites from January 1 to December 31, 2019. Medical records were reviewed, isolates were collected and characterized including antimicrobial susceptibility testing and whole genome sequencing. RESULTS: Among 136 incident cases in 2019, 66 isolates were collected and characterized; 56.5% were from cases who were male, 54.5% were from persons of Black or African American race with non-Hispanic ethnicity, and the median age was 63.5 years. Most isolates, 77.2%, were isolated from urine, and 50.0% were collected in the outpatient setting; 72.7% of isolates harbored an acquired carbapenemase gene (aCP), predominantly blaOXA-23 or blaOXA-24/40; however, an isolate with blaNDM was identified. The antimicrobial agent with the most in vitro activity was cefiderocol (96.9% of isolates were susceptible). CONCLUSIONS: Our surveillance found that CRAB isolates in the U.S. commonly harbor an aCP, have an antimicrobial susceptibility profile that is defined as difficult-to-treat resistance, and epidemiologically are similar regardless of the presence of an aCP.

A pilot study of genetic variants in dopamine regulators with indoor tanning and melanoma.

Many people frequently tan indoors despite being aware of the increased risk of melanoma. Ultraviolet radiation is hypothesized to modify biological reward pathways, for example, through the dopamine neurotransmitter system, to reinforce tanning behaviour. In this pilot study, we relied on questionnaire and DNA data from a recently completed case-control study to examine 67 single-nucleotide polymorphisms (SNPs) and related haplotypes in five dopamine receptor and drug metabolism genes in relation to indoor tanning among controls. We also examined the association between individual SNPS and likelihood of melanoma, adjusting for or stratifying on indoor tanning status. In candidate and haplotype gene analyses, variants only in the DRD2 dopamine receptor and ANKK1 signalling genes were positively associated with indoor tanning use among controls; only associations for ANKK1 remained statistically significant (P < 0.05) after adjustment. Several SNPs in ANKK1 and DRD2 associated with indoor tanning among controls were also found to be associated with increased risk of melanoma. Upon stratifying for indoor tanning status, one ANKK1 SNP was positively associated with melanoma among non-tanners, while three DRD2 SNPS were positively associated with melanoma among tanners or non-tanners, depending on the SNP. These alleles represent important genomic regions to further explore addictive tanning behaviour.

Sex-specific association of sequence variants in CBS and MTRR with risk for promoter hypermethylation in the lung epithelium of smokers.

Gene promoter hypermethylation is now regarded as a promising biomarker for the risk and progression of lung cancer. The one-carbon metabolism pathway is postulated to affect deoxyribonucleic acid (DNA) methylation because it is responsible for the generation of S-adenosylmethionine (SAM), the methyl donor for cellular methylation reactions. This study investigated the association of single nucleotide polymorphisms (SNPs) in six one-carbon metabolism-related genes with promoter hypermethylation in sputum DNA from non-Hispanic white smokers in the Lovelace Smokers Cohort (LSC) (n = 907). Logistic regression was used to assess the association of SNPs with hypermethylation using a high/low methylation cutoff. SNPs in the cystathionine beta synthase (CBS) and 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) genes were significantly associated with high methylation in males [CBS rs2850146 (-8283G > C), OR = 4.9; 95% CI: 1.98, 12.2, P = 0.0006] and low methylation in females [MTRR rs3776467 (7068A > G), OR = 0.57, 95% CI: 0.42, 0.77, P = 0.0003]. The variant allele of rs2850146 was associated with reduced gene expression and increased plasma homocysteine (Hcy) concentrations. Three plasma metabolites, Hcy, methionine and dimethylglycine, were associated with increased risk for gene methylation. These studies suggest that SNPs in CBS and MTRR have sex-specific associations with aberrant methylation in the lung epithelium of smokers that could be mediated by the affected one-carbon metabolism and transsulfuration in the cells.

Comparison of the Risk of Recurrent Clostridioides Difficile Infections Among Patients in 2018 Versus 2013.

Among persons with an initial Clostridioides difficile infection (CDI) across 10 US sites in 2018 compared with 2013, 18.3% versus 21.1% had ≥1 recurrent CDI (rCDI) within 180 days. We observed a 16% lower adjusted risk of rCDI in 2018 versus 2013 (P < .0001).

Epidemiology of extended-spectrum ß-lactamase-producing Enterobacterales in five US sites participating in the Emerging Infections Program, 2017.

OBJECTIVE: The incidence of infections from extended-spectrum ß-lactamase (ESBL)-producing Enterobacterales (ESBL-E) is increasing in the United States. We describe the epidemiology of ESBL-E at 5 Emerging Infections Program (EIP) sites. METHODS: During October-December 2017, we piloted active laboratory- and population-based (New York, New Mexico, Tennessee) or sentinel (Colorado, Georgia) ESBL-E surveillance. An incident case was the first isolation from normally sterile body sites or urine of Escherichia coli or Klebsiella pneumoniae/oxytoca resistant to ≥1 extended-spectrum cephalosporin and nonresistant to all carbapenems tested at a clinical laboratory from a surveillance area resident in a 30-day period. Demographic and clinical data were obtained from medical records. The Centers for Disease Control and Prevention (CDC) performed reference antimicrobial susceptibility testing and whole-genome sequencing on a convenience sample of case isolates. RESULTS: We identified 884 incident cases. The estimated annual incidence in sites conducting population-based surveillance was 199.7 per 100,000 population. Overall, 800 isolates (96%) were from urine, and 790 (89%) were E. coli. Also, 393 cases (47%) were community-associated. Among 136 isolates (15%) tested at the CDC, 122 (90%) met the surveillance definition phenotype; 114 (93%) of 122 were shown to be ESBL producers by clavulanate testing. In total, 111 (97%) of confirmed ESBL producers harbored a blaCTX-M gene. Among ESBL-producing E. coli isolates, 52 (54%) were ST131; 44% of these cases were community associated. CONCLUSIONS: The burden of ESBL-E was high across surveillance sites, with nearly half of cases acquired in the community. EIP has implemented ongoing ESBL-E surveillance to inform prevention efforts, particularly in the community and to watch for the emergence of new ESBL-E strains.

Preferences for multigene panel testing for hereditary breast cancer risk among ethnically diverse BRCA-uninformative families.

Until recently, genetic testing for hereditary breast cancer has primarily focused on pathogenic variants in the BRCA1 and BRCA2 (BRCA) genes. However, advances in DNA sequencing technologies have made simultaneous testing for multiple genes possible. We examined correlates of interest in multigene panel testing and risk communication preferences in an ethnically diverse sample of women who tested negative for BRCA mutations previously but remain at high risk based on their family history (referred to as "BRCA-uninformative") and their at-risk female family members. Two-hundred and thirteen women with a previous breast cancer diagnosis and a BRCA-uninformative test result and their first-degree relatives completed a survey on interest in multigene panel testing, communication preferences, and sociodemographic, psychological, and clinical factors. Stepwise logistic regression was used to identify factors associated with testing interest. Chi-square analyses were used to test differences in risk communication preferences. Interest in multigene panel testing was high (84%) and did not considerably differ by cancer status or ethnicity. In multivariable analysis, factors significantly associated with interest in genetic testing were having had a mammogram in the past 2 years (odds ratio (OR) = 4.04, 95% confidence interval (CI) 1.80-9.02) and high cancer worry (OR = 3.77, 95% CI 1.34-10.60). Overall, the most commonly preferred genetic communication modes were genetic counselors, oncologists, and print materials. However, non-Hispanic women were more likely than Hispanic women to prefer web-based risk communication (p < 0.001). Hispanic and non-Hispanic women from BRCA-uninformative families have a high level of interest in gene panel testing. Cancer-related emotions and communication preferences should be considered in developing targeted genetic risk communication strategies.

ATM requirement in gene expression responses to ionizing radiation in human lymphoblasts and fibroblasts.

The heritable disorder ataxia telangiectasia (AT) is caused by mutations in the AT-mutated (ATM) gene with manifestations that include predisposition to lymphoproliferative cancers and hypersensitivity to ionizing radiation (IR). We investigated gene expression changes in response to IR in human lymphoblasts and fibroblasts from seven normal and seven AT-affected individuals. Both cell types displayed ATM-dependent gene expression changes after IR, with some responses shared and some responses varying with cell type and dose. Interestingly, after 5 Gy IR, lymphoblasts displayed ATM-independent responses not seen in the fibroblasts at this dose, which likely reflect signaling through ATM-related kinases, e.g., ATR, in the absence of ATM function.

Genetic Testing in a Population-Based Sample of Breast and Ovarian Cancer Survivors from the REACH Randomized Trial: Cost Barriers and Moderators of Counseling Mode.

Background: This study evaluates predictors of BRCA1/2 testing among breast and ovarian cancer survivors who received genetic counseling as part of a randomized trial and evaluates moderators of counseling mode on testing uptake.Methods: Predictors of BRCA1/2 testing within one year postcounseling were evaluated using multivariable logistic regression in a population-based sample of breast and ovarian cancer survivors at increased hereditary risk randomly assigned to in-person counseling (IPC; n = 379) versus telephone counseling (TC; n = 402). Variables that moderated the association between counseling mode and testing were identified by subgroup analysis.Results: Testing uptake was associated with higher perceived comparative mutation risk [OR = 1.32; 95% confidence interval (CI), 1.11-1.57] in the adjusted analysis. Those without cost barriers had higher testing uptake (OR = 18.73; 95% CI, 7.09-49.46). Psychologic distress and perceived comparative mutation risk moderated the effect of counseling and testing. Uptake between IPC versus TC did not differ at low levels of distress and risk, but differed at high distress (26.3% TC vs. 44.3% IPC) and high perceived comparative risk (33.9% TC vs. 50.5% IPC).Conclusions: Cost concerns are a strong determinant of testing. Differences in testing uptake by counseling mode may depend on precounseling distress and risk perceptions.Impact: Cost concerns may contribute to low testing in population-based samples of at-risk cancer survivors. Precounseling psychosocial characteristics should be considered when offering in-person versus telephone counseling. Cancer Epidemiol Biomarkers Prev; 26(12); 1772-80. ©2017 AACR.

Randomized Noninferiority Trial of Telephone Delivery of BRCA1/2 Genetic Counseling Compared With In-Person Counseling: 1-Year Follow-Up.

PURPOSE: The ongoing integration of cancer genomic testing into routine clinical care has led to increased demand for cancer genetic services. To meet this demand, there is an urgent need to enhance the accessibility and reach of such services, while ensuring comparable care delivery outcomes. This randomized trial compared 1-year outcomes for telephone genetic counseling with in-person counseling among women at risk of hereditary breast and/or ovarian cancer living in geographically diverse areas. PATIENTS AND METHODS: Using population-based sampling, women at increased risk of hereditary breast and/or ovarian cancer were randomly assigned to in-person (n = 495) or telephone genetic counseling (n = 493). One-sided 97.5% CIs were used to estimate the noninferiority effects of telephone counseling on 1-year psychosocial, decision-making, and quality-of-life outcomes. Differences in test-uptake proportions for determining equivalency of a 10% prespecified margin were evaluated by 95% CIs. RESULTS: At the 1-year follow-up, telephone counseling was noninferior to in-person counseling for all psychosocial and informed decision-making outcomes: anxiety (difference [d], 0.08; upper bound 97.5% CI, 0.45), cancer-specific distress (d, 0.66; upper bound 97.5% CI, 2.28), perceived personal control (d, -0.01; lower bound 97.5% CI, -0.06), and decisional conflict (d, -0.12; upper bound 97.5% CI, 2.03). Test uptake was lower for telephone counseling (27.9%) than in-person counseling (37.3%), with the difference of 9.4% (95% CI, 2.2% to 16.8%). Uptake was appreciably higher for rural compared with urban dwellers in both counseling arms. CONCLUSION: Although telephone counseling led to lower testing uptake, our findings suggest that telephone counseling can be effectively used to increase reach and access without long-term adverse psychosocial consequences. Further work is needed to determine long-term adherence to risk management guidelines and effective strategies to boost utilization of primary and secondary preventive strategies.

Efficacy of a Telehealth Intervention on Colonoscopy Uptake When Cost Is a Barrier: The Family CARE Cluster Randomized Controlled Trial.

BACKGROUND: We tested the efficacy of a remote tailored intervention Tele-Cancer Risk Assessment and Evaluation (TeleCARE) compared with a mailed educational brochure for improving colonoscopy uptake among at-risk relatives of colorectal cancer patients and examined subgroup differences based on participant reported cost barriers. METHODS: Family members of colorectal cancer patients who were not up-to-date with colonoscopy were randomly assigned as family units to TeleCARE (N = 232) or an educational brochure (N = 249). At the 9-month follow-up, a cost resource letter listing resources for free or reduced-cost colonoscopy was mailed to participants who had reported cost barriers and remained nonadherent. Rates of medically verified colonoscopy at the 15-month follow-up were compared on the basis of group assignment and within group stratification by cost barriers. RESULTS: In intent-to-treat analysis, 42.7% of participants in TeleCARE and 24.1% of participants in the educational brochure group had a medically verified colonoscopy [OR, 2.37; 95% confidence interval (CI) 1.59-3.52]. Cost was identified as a barrier in both groups (TeleCARE = 62.5%; educational brochure = 57.0%). When cost was not a barrier, the TeleCARE group was almost four times as likely as the comparison to have a colonoscopy (OR, 3.66; 95% CI, 1.85-7.24). The intervention was efficacious among those who reported cost barriers; the TeleCARE group was nearly twice as likely to have a colonoscopy (OR, 1.99; 95% CI, 1.12-3.52). CONCLUSIONS: TeleCARE increased colonoscopy regardless of cost barriers. IMPACT: Remote interventions may bolster screening colonoscopy regardless of cost barriers and be more efficacious when cost barriers are absent.

ATM-dependent and -independent gene expression changes in response to oxidative stress, gamma irradiation, and UV irradiation.

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by progressive cerebellar degeneration, immunodeficiencies, telangiectasias, sensitivity to ionizing radiation, and high predisposition for malignancies. The ataxia telangiectasia mutated (ATM) gene encodes a protein (ATM) with serine/threonine kinase activity. DNA-double strand breaks are known to increase its kinase activity. While cells from individuals with AT are attenuated in their G(1)-, S- and G(2)-phase cell cycle checkpoint functions in response to gamma irradiation and oxidative stress, their response to UV irradiation appears to be equivalent to that of wild-type cells. In this study, we investigated changes in gene expression in response to gamma irradiation, oxidative stress, and UV irradiation, focusing on the dependence on ATM. Doses for all three treatments were selected that resulted in roughly an equivalent induction of a G(1) checkpoint response and inhibition of progression through S phase. To investigate gene expression changes, logarithmically growing wild-type and AT dermal diploid fibroblasts were exposed to either gamma radiation (5 Gy), oxidative stress (75 micro M t-butyl-hydroperoxide), or UV radiation (7.5 J/m(2)), and RNA was harvested 6 h after treatment. Gene expression analysis was performed using the NIEHS Human ToxChip 2.0 with approximately 1900 cDNA clones representing known genes and ESTs. All three treatments resulted in distinct patterns of gene expression changes, as shown previously. ATM-dependent and ATM-independent components were detected within these patterns, as were novel indications of involvement of ATM in regulation of transcription factors such as SP1, AP1 and MTF1.

Expanding access to BRCA1/2 genetic counseling with telephone delivery: a cluster randomized trial.

BACKGROUND: The growing demand for cancer genetic services underscores the need to consider approaches that enhance access and efficiency of genetic counseling. Telephone delivery of cancer genetic services may improve access to these services for individuals experiencing geographic (rural areas) and structural (travel time, transportation, childcare) barriers to access. METHODS: This cluster-randomized clinical trial used population-based sampling of women at risk for BRCA1/2 mutations to compare telephone and in-person counseling for: 1) equivalency of testing uptake and 2) noninferiority of changes in psychosocial measures. Women 25 to 74 years of age with personal or family histories of breast or ovarian cancer and who were able to travel to one of 14 outreach clinics were invited to participate. Randomization was by family. Assessments were conducted at baseline one week after pretest and post-test counseling and at six months. Of the 988 women randomly assigned, 901 completed a follow-up assessment. Cluster bootstrap methods were used to estimate the 95% confidence interval (CI) for the difference between test uptake proportions, using a 10% equivalency margin. Differences in psychosocial outcomes for determining noninferiority were estimated using linear models together with one-sided 97.5% bootstrap CIs. RESULTS: Uptake of BRCA1/2 testing was lower following telephone (21.8%) than in-person counseling (31.8%, difference = 10.2%, 95% CI = 3.9% to 16.3%; after imputation of missing data: difference = 9.2%, 95% CI = -0.1% to 24.6%). Telephone counseling fulfilled the criteria for noninferiority to in-person counseling for all measures. CONCLUSIONS: BRCA1/2 telephone counseling, although leading to lower testing uptake, appears to be safe and as effective as in-person counseling with regard to minimizing adverse psychological reactions, promoting informed decision making, and delivering patient-centered communication for both rural and urban women.

The A/G allele of rs16906252 predicts for MGMT methylation and is selectively silenced in premalignant lesions from smokers and in lung adenocarcinomas.

PURPOSE: To address the association between sequence variants within the MGMT (O(6)-methylguanine-DNA methyltransferase) promoter-enhancer region and methylation of MGMT in premalignant lesions from smokers and lung adenocarcinomas, their biological effects on gene regulation, and targeting MGMT for therapy. EXPERIMENTAL DESIGN: Single nucleotide polymorphisms (SNP) identified through sequencing a 1.9 kb fragment 5' of MGMT were examined in relation to MGMT methylation in 169 lung adenocarcinomas and 1,731 sputum samples from smokers. The effect of promoter haplotypes on MGMT expression was tested using a luciferase reporter assay and cDNA expression analysis along with allele-specific sequencing for methylation. The response of MGMT methylated lung cancer cell lines to the alkylating agent temozolomide (TMZ) was assessed. RESULTS: The A allele of rs16906252 and the haplotype containing this SNP were strongly associated with increased risk for MGMT methylation in adenocarcinomas (ORs ≥ 94). This association was observed to a lesser extent in sputum samples in both smoker cohorts. The A allele was selectively methylated in primary lung tumors and cell lines heterozygous for rs16906252. With the most common haplotype as the reference, a 20 to 41% reduction in promoter activity was seen for the haplotype carrying the A allele that correlated with lower MGMT expression. The sensitivity of lung cancer cell lines to TMZ was strongly correlated with levels of MGMT methylation and expression. CONCLUSIONS: These studies provide strong evidence that the A allele of a MGMT promoter-enhancer SNP is a key determinant for MGMT methylation in lung carcinogenesis. Moreover, TMZ treatment may benefit a subset of lung cancer patients methylated for MGMT.

Multivitamins, folate, and green vegetables protect against gene promoter methylation in the aerodigestive tract of smokers.

One promising approach for early detection of lung cancer is by monitoring gene promoter hypermethylation events in sputum. Epidemiologic studies suggest that dietary fruits and vegetables and the micronutrients they contain may reduce risk of lung cancer. In this study, we evaluated whether diet and multivitamin use influenced the prevalence of gene promoter methylation in cells exfoliated from the aerodigestive tract of current and former smokers. Members (N = 1,101) of the Lovelace Smokers Cohort completed the Harvard Food Frequency Questionnaire and provided a sputum sample that was assessed for promoter methylation of eight genes commonly silenced in lung cancer and associated with risk for this disease. Methylation status was categorized as low (fewer than two genes methylated) or high (two or more genes methylated). Logistic regression models were used to identify associations between methylation status and 21 dietary variables hypothesized to affect the acquisition of gene methylation. Significant protection against methylation was observed for leafy green vegetables [odds ratio (OR) = 0.83 per 12 monthly servings; 95% confidence interval (95% CI), 0.74-0.93] and folate (OR, 0.84 per 750 microg/d; 95% CI, 0.72-0.99). Protection against gene methylation was also seen with current use of multivitamins (OR, 0.57; 95% CI, 0.40-0.83). This is the first cohort-based study to identify dietary factors associated with reduced promoter methylation in cells exfoliated from the airway epithelium of smokers. Novel interventions to prevent lung cancer should be developed based on the ability of diet and dietary supplements to affect reprogramming of the epigenome.

Thymic model for examining BRCA2 expression and function.

Mutations in the human BRCA2 breast cancer susceptibility gene are associated with increased risks of breast, ovarian, and other cancers. BRCA2 has been hypothesized to function in processes of DNA damage/breakage repair, cell proliferation, and apoptosis. These processes continually occur in the thymus during thymocyte development, and BRCA2 mRNA is highly expressed in thymus relative to most other organs. We therefore used the thymus as a model system to study BRCA2 expression and function. Quantitative reverse transcription polymerase chain reaction experiments showed that highly activated immature CD4(+) CD8(+) double-positive human thymocytes that exhibited high levels of proliferation and apoptosis had increased BRCA2 mRNA levels relative to other thymocyte subsets. BRCA2 mRNA levels were upregulated in thymocytes treated with the DNA-damaging agent etoposide. Only modest increases were associated with proliferation in human peripheral lymphocytes in response to concanavalin A (ConA) mitogen. Mice homozygous for a targeted mutation in Brca2 exon 27 (Brca2(Delta27/Delta27)) showed normal thymic architecture but had 18% decreased thymocyte cellularity compared with wild-type mice. Thymocytes from these Brca2(Delta27/Delta27) mice displayed decreased apoptosis in response to etoposide-induced DNA damage compared with wild-type thymocytes. These studies suggest that BRCA2 mRNA levels are modulated during DNA damage and may be important during apoptosis.

ATR enforces the topoisomerase II-dependent G2 checkpoint through inhibition of Plk1 kinase.

An ATR-dependent G(2) checkpoint responds to inhibition of topoisomerase II and delays entry into mitosis by sustaining nuclear exclusion of cyclin B1-Cdk1 complexes. Here we report that induction of this checkpoint with ICRF-193, a topoisomerase II catalytic inhibitor that does not cause DNA damage, was associated with an ATR-dependent inhibition of polo-like kinase 1 (Plk1) kinase activity and a decrease in cyclin B1 phosphorylation. Expression of constitutively active Plk1 but not wild type Plk1 reversed ICRF-193-induced mitotic delay in HeLa cells, suggesting that Plk1 kinase activity is important for the checkpoint response to ICRF-193. G(2)/M synchronized normal human fibroblasts, when treated with ICRF-193, showed a decrease in cyclin B1 phosphorylation and Plk1 kinase activity despite high cyclin B1-Cdk1 kinase activity. G(2) fibroblasts that were treated with caffeine to override the checkpoint response to ICRF-193 displayed a high incidence of chromosomal aberrations. Taken together, these results suggest that ATR-dependent inhibition of Plk1 kinase activity may be one mechanism to regulate cyclin B1 phosphorylation and sustain nuclear exclusion during the G(2) checkpoint response to topoisomerase II inhibition. Moreover, the results demonstrate an important role for the topoisomerase II-dependent G(2) checkpoint in the preservation of human genomic stability.

Identification of distinct and common gene expression changes after oxidative stress and gamma and ultraviolet radiation.

The human genome is exposed to many different kinds of DNA-damaging agents. While most damage is detected and repaired through complex damage recognition and repair machineries, some damage has the potential to escape these mechanisms. Unrepaired DNA damage can give rise to alterations and mutations in the genome in an individual cell, which can result in malignant transformation, especially when critical genes are deregulated. In this study, we investigated gene expression changes in response to oxidative stress, gamma (gamma) radiation, and ultraviolet (UV) radiation and their potential implications in cancer development. Doses were selected for each of the three treatments, based on their ability to cause a similar G(1) checkpoint induction and slow down in early S-phase progression, as reflected by a comparable reduction in cyclin E-associated kinase activity of at least 75% in logarithmically growing human dermal diploid fibroblasts. To investigate gene expression changes, logarithmically growing dermal diploid fibroblasts were exposed to either gamma radiation (5 Gy), oxidative stress (75 microM of tert-butyl hydroperoxide (t-butyl-OOH)), or UV radiation (UVC) (7.5 J/m(2)) and RNA was harvested 6 h after treatment. Gene expression was analyzed using the NIEHS Human ToxChip 2.0 with approximately 1901 cDNA clones representing known genes and expressed sequence tags (ESTs). We were able to identify common and distinct responses in dermal diploid fibroblasts to the three different stimuli used. Within our analysis, gene expression profiles in response to gamma radiation and oxidative stress appeared to be more similar than profiles expressed after UV radiation. Interestingly, equivalent cyclin E-associated kinase activity reduction with all the three treatments was associated with greater transcriptional changes after UV radiation than after gamma radiation and oxidative stress. While samples treated with UV radiation displayed modulations of their mitogen activated protein kinase (MAPK) pathway, gamma radiation had its major influence on cell-cycle progression in S-phase and mitosis. In addition, cell cultures from different individuals displayed significant differences in their gene expression responses to DNA damage.