Kriste A. Lewis

Heterozygous ATR Mutations in Mismatch Repair–Deficient Cancer Cells Have Functional Significance

ATR (ataxia telangiectasia and Rad3-related) function is necessary for the proper response to commonly used chemotherapeutic agents. Heterozygous truncating mutations in exon 10 of the ATR gene have been described in numerous cancers exhibiting microsatellite instability. We show that truncating mutations of ATR are capable of acting in a dominant-negative manner to abrogate ATR-dependent Chk1 phosphorylation and cell-cycle arrests after DNA damage. In addition, endometrial cell lines harboring ATR mutations are defective for ATR-dependent responses. These findings imply that ATR mutations play an important role in the development and clinical behavior of a subset of microsatellite instability-positive endometrial, colon, and stomach cancers.

Mutations in the ataxia telangiectasia and rad3-related-checkpoint kinase 1 DNA damage response axis in colon cancers.

In response to certain types of DNA damage, ataxia telangiectasia and rad3‐related (ATR) phosphorylates checkpoint kinase 1 (CHEK1) resulting in cell cycle arrest and subsequent DNA repair. ATR and CHEK1 contain mononucleotide microsatellite repeat regions, which are mutational targets in tumors with defective mismatch repair (MMR). This study examined the frequency of such mutations in colon cancers and their impact on biologic behavior. Screening for ATR mutations in 48 tumors was performed using denaturing high‐performance liquid chromatography (DHPLC) and confirmed with sequencing analysis. The CHEK1 exon 7 A(9) region was sequenced in 20 of the 27 (74%) tumors with high frequency of microsatellite instability (MSI‐H). Univariate and multivariate analyses were used to examine associations with clinical outcomes. Frequent mutations in MSI‐H colon cancers were identified within the ATR (37%)/CHEK1(5%) damage response pathway. Stage and MSI status both independently predicted overall survival (OS) and disease‐free survival (DFS). ATR status was not associated with stage, but was associated with a trend toward improved DFS: 0/9 cancers recurred in MSI‐H cases harboring ATR mutations vs. 4/18 recurrences in MSI‐H cases without ATR mutations. This suggests that ATR mutations may affect clinical behavior and response to therapy in MSI‐H colon cancers.

Characteristics of Heart Rate Variability in Alcohol-Dependent Subjects and Nondependent Chronic Alcohol Users

Heart rate variability (HRV) is an objective and sensitive measure of integrated physiological functioning reflective of heart rhythm responsivity to internal and external demands. Reduced HRV is associated with vulnerability to stress and deterioration of medical and/or psychiatric conditions, while increased HRV is associated with a favorable treatment response and recovery from various medical and/or psychiatric conditions. Our previous review found that acute alcohol consumption caused decreased parasympathetic and increased sympathetic HRV effects in both nonalcoholic and chronic alcohol users. This review investigates the effects of chronic alcohol consumption on HRV in alcohol-dependent subjects and nondependent users. MEDLINE, Scopus, and PubMed were searched for human experimental and clinical trials that measured the effects of chronic alcohol use on HRV. Only publications that included a description of their study designs and clearly stated methodologies for data collections, and outcome measures were reviewed. We have reviewed a total of 24 articles. In nondependent users, low dose (approximating the recommended daily amount of 1 standard drink in women and 2 in men) use is associated with increased HRV parameters compared to those who drink less frequently or abstain altogether. A further increase in consumption is associated with decreased HRV compared to both abstainers and more moderate drinkers. HRV changes during withdrawal generally follow the same negative direction but are more complex and less understood. In dependent subjects, an improvement in HRV was seen following abstinence but remained reduced compared to nonalcoholic controls. This review demonstrates that HRV changes associated with chronic use follow a J-shaped curve. It supports recommendations that limit daily alcohol intake to no more than 2 drinks for men and 1 drink for women. Future studies should investigate HRV as a biomarker of alcoholism development and treatment response as well as the physiological basis for alcohol effects on HRV.

Ataxia telangiectasia and rad3-related kinase contributes to cell cycle arrest and survival after cisplatin but not oxaliplatin

The DNA cross-linking agents cisplatin and oxaliplatin are widely used in the treatment of human cancer. Lesions produced by these agents are widely known to activate the G1 and G2 cell cycle checkpoints. Less is known about the role of the intra–S-phase checkpoint in the response to these agents. In the present study, two different cell lines expressing a dominant-negative kinase dead (kd) version of the ataxia telangiectasia and rad3-related (ATR) kinase in an inducible fashion were examined for their responses to these two platinating agents and a variety of other DNA cross-linking drugs. The expression of the kdATR allele markedly sensitized the cells to cisplatin, but not to oxaliplatin, as assessed by inhibition of colony formation, induction of apoptosis, and cell cycle analysis. Similar differences in survival were noted for melphalan (ATR dependent) and 4-hydroperoxycyclophosphamide (ATR independent). Further experiments showed that ATR function is not necessary for removal of Pt-DNA adducts. The predominant difference between the responses to the two platinum drugs was the presence of a drug-specific ATR-dependent S-phase arrest after cisplatin but not oxaliplatin. These results indicate that involvement of ATR in the response to DNA cross-linking agents is lesion specific. This observation might need to be taken into account in the development and use of ATR or Chk1 inhibitors. [Mol Cancer Ther 2009;8(4):855–63]

Association of GATA4 sequence variation with alcohol dependence

To further explore reports of association of alcohol dependence and response to acamprosate treatment with the GATA4 rs13273672 single nucleotide polymorphism (SNP), we genotyped this and 10 other GATA4 SNPs in 816 alcohol‐dependent cases and 1248 controls. We tested for association of alcohol dependence with the 11 SNPs individually and performed a global test for association using a principle components analysis. Our analyses demonstrate significant association between GATA4 and alcohol dependence at the gene level (P = 0.009) but no association with rs13273672. Further studies are needed to identify potential causal GATA4 variation(s) and the functional mechanism(s) contributing to this association.

Gender-specific effects of comorbid depression and anxiety on the propensity to drink in negative emotional states

Abstract Background and Aims Depression and anxiety are often comorbid with alcoholism and contribute to craving and relapse. We aimed to estimate the prevalence of life‐time diagnoses of major depressive disorder (MDD), substance‐induced depression (SID), anxiety disorder (AnxD) and substance‐induced anxiety (SIA), the effects of these comorbidities on the propensity to drink in negative emotional states (negative craving), and test whether these effects differ by sex. Design Secondary analyses of baseline data collected in a single‐arm study of pharmacogenetic predictors of acamprosate response. Setting Academic medical center and affiliated community‐based treatment programs in the American upper mid‐west. Participants A total of 287 males and 156 females aged 18–80 years, meeting DSM‐IV criteria for alcohol dependence. Measurements The primary outcome measure was ‘propensity to drink in negative emotional situations’ (determined by the Inventory of Drug Taking Situations) and the key predictors/covariates were sex and psychiatric comorbidities, including MDD, SID, AnxD and SIA (determined by Psychiatric Research Interview of Substance and Mood Disorders). Findings The prevalence of the MDD, SID and AnxD was higher in females compared with males (33.1 versus 18.4%, 44.8 versus 26.4% and 42.2 versus 27.4%, respectively; P < 0.01, each), while SIA was rare (3.3%) and did not differ by sex. Increased propensity to drink in negative emotional situations was associated with comorbid MDD (β = 6.6, P = 0.013) and AnxD (β = 4.8, P = 0.042) as well as a SID × sex interaction effect (P = 0.003), indicating that the association of SID with propensity to drink in negative emotional situations differs by sex and is stronger in males (β = 7.9, P = 0.009) compared with females (β = −6.6, P = 0.091). Conclusions There appears to be a higher prevalence of comorbid depression and anxiety disorders as well as propensity to drink in negative emotional situations in female compared with male alcoholics. Substance‐induced depression appears to have a sex‐specific effect on the increased risk for drinking in negative emotional situations in males.