Synthesis of A83586C/citropeptin hybrid and synthetic studies toward azinothricin

The Azinothricin family of cyclodepsipeptides are a class of antitumour antibiotics whose antitumour properties are attributed to their ability to selectively repress the expression of genes essential for the progression of the cell cycle from G1 to S phase. They have been shown to inhibit E2F transcription factors, which are critical regulators of mammalian cellular proliferation. This biological observation has made them a potentially important new therapeutic target for the control of proliferative diseases, such as cancer. An asymmetric total synthesis of an A83586C-citropeptin hybrid is presented in this thesis, along with a synthetic route to the azinothricin cyclodepsipeptide. The A83586C- citropeptin hybrid will serve as a useful intracellular probe that will provide valuable insights into the mechanism of the antitumour action of this class, which may contribute to a greater understanding of cancer biology. The cyclodepsipeptide components of these molecules have been assembled via a 2+2+2 -fragment condensation strategy and a HATU-mediated macrolactamisation. In the case of the A83586C-citropeptin hybrid, a chemoselective coupling was performed between the fully elaborated N-hydroxybenzotriazole activated ester and the citropeptin cyclodepsipeptide

Attitudes toward Precision Treatment of Smoking in the Southern Community Cohort Study

Background: Precision interventions using biological data may enhance smoking treatment, yet are understudied among smokers who are disproportionately burdened by smoking-related disease. Methods: We surveyed smokers in the NCI-sponsored Southern Community Cohort Study, consisting primarily of African-American, low-income adults. Seven items assessed attitudes toward aspects of precision smoking treatment, from undergoing tests to acting on results. Items were dichotomized as favorable (5 = strongly agree/4 = agree) versus less favorable (1 = strongly disagree/2 = disagree/3 = neutral); a summary score reflecting generalized attitudes was also computed. Multivariable logistic regression tested independent associations of motivation (precontemplation, contemplation, and preparation) and confidence in quitting (low, medium, and high) with generalized attitudes, controlling for sociodemographic factors and nicotine dependence. Results: More than 70% of respondents endorsed favorable generalized attitudes toward precision medicine, with individual item favorability ranging from 64% to 83%. Smokers holding favorable generalized attitudes reported higher income and education (P \u3c 0.05). Predicted probabilities of favorable generalized attitudes ranged from 63% to 75% across motivation levels [contemplation vs. precontemplation: adjusted odds ratio (AOR) = 2.10, 95% confidence interval (CI), 1.36–3.25, P = 0.001; preparation vs. precontemplation: AOR = 1.83, 95% CI, 1.20–2.78, P = 0.005; contemplation vs. preparation: AOR = 1.15, 95% CI, 0.75–1.77, P = 0.52] and from 59% to 78% across confidence (medium vs. low: AOR = 1.91, 95% CI, 1.19–3.07, P = 0.007; high vs. low: AOR = 2.62, 95% CI, 1.68–4.10, P \u3c 0.001; medium vs. high: AOR = 0.73, 95% CI, 0.48–1.11, P = 0.14). Conclusions: Among disproportionately burdened community smokers, most hold favorable attitudes toward precision smoking treatment. Individuals with lower motivation and confidence to quit may benefit from additional intervention to engage with precision smoking treatment. Impact: Predominantly favorable attitudes toward precision smoking treatment suggest promise for future research testing their effectiveness and implementation

Circulating vitamin D concentrations and risk of breast and prostate cancer: a Mendelian randomization study.

BACKGROUND: Observational studies have suggested an association between circulating vitamin D concentrations [25(OH)D] and risk of breast and prostate cancer, which was not supported by a recent Mendelian randomization (MR) analysis comprising 15 748 breast and 22 898 prostate-cancer cases. Demonstrating causality has proven challenging and one common limitation of MR studies is insufficient power. METHODS: We aimed to determine whether circulating concentrations of vitamin D are causally associated with the risk of breast and prostate cancer, by using summary-level data from the largest ever genome-wide association studies conducted on vitamin D (N = 73 699), breast cancer (Ncase = 122 977) and prostate cancer (Ncase = 79 148). We constructed a stronger instrument using six common genetic variants (compared with the previous four variants) and applied several two-sample MR methods. RESULTS: We found no evidence to support a causal association between 25(OH)D and risk of breast cancer [OR per 25 nmol/L increase, 1.02 (95% confidence interval: 0.97-1.08), P = 0.47], oestrogen receptor (ER)+ [1.00 (0.94-1.07), P = 0.99] or ER- [1.02 (0.90-1.16), P = 0.75] subsets, prostate cancer [1.00 (0.93-1.07), P = 0.99] or the advanced subtype [1.02 (0.90-1.16), P = 0.72] using the inverse-variance-weighted method. Sensitivity analyses did not reveal any sign of directional pleiotropy. CONCLUSIONS: Despite its almost five-fold augmented sample size and substantially improved statistical power, our MR analysis does not support a causal effect of circulating 25(OH)D concentrations on breast- or prostate-cancer risk. However, we can still not exclude a modest or non-linear effect of vitamin D. Future studies may be designed to understand the effect of vitamin D in subpopulations with a profound deficiency

Genetically Predicted Body Mass Index and Breast Cancer Risk : Mendelian Randomization Analyses of Data from 145,000 Women of European Descent

Background Observational epidemiological studies have shown that high body mass index (BMI) is associated with a reduced risk of breast cancer in premenopausal women but an increased risk in postmenopausal women. It is unclear whether this association is mediated through shared genetic or environmental factors. Methods We applied Mendelian randomization to evaluate the association between BMI and risk of breast cancer occurrence using data from two large breast cancer consortia. We created a weighted BMI genetic score comprising 84 BMI-associated genetic variants to predicted BMI. We evaluated genetically predicted BMI in association with breast cancer risk using individual-level data from the Breast Cancer Association Consortium (BCAC) (cases = 46,325, controls = 42,482). We further evaluated the association between genetically predicted BMI and breast cancer risk using summary statistics from 16,003 cases and 41,335 controls from the Discovery, Biology, and Risk of Inherited Variants in Breast Cancer (DRIVE) Project. Because most studies measured BMI after cancer diagnosis, we could not conduct a parallel analysis to adequately evaluate the association of measured BMI with breast cancer risk prospectively. Results In the BCAC data, genetically predicted BMI was found to be inversely associated with breast cancer risk (odds ratio [OR] = 0.65 per 5 kg/m(2) increase, 95% confidence interval [CI]: 0.56-0.75, p = 3.32 x 10(-10)). The associations were similar for both premenopausal (OR = 0.44, 95% CI: 0.31-0.62, p = 9.91x10(-8)) and postmenopausal breast cancer (OR = 0.57, 95% CI: 0.46-0.71, p = 1.88x10(-8)). This association was replicated in the data from the DRIVE consortium (OR = 0.72, 95% CI: 0.60-0.84, p = 1.64 x 10(-7)). Single marker analyses identified 17 of the 84 BMI-associated single nucleotide polymorphisms (SNPs) in association with breast cancer risk at p <0.05; for 16 of them, the allele associated with elevated BMI was associated with reduced breast cancer risk. Conclusions BMI predicted by genome-wide association studies (GWAS)-identified variants is inversely associated with the risk of both pre- and postmenopausal breast cancer. The reduced risk of postmenopausal breast cancer associated with genetically predicted BMI observed in this study differs from the positive association reported from studies using measured adult BMI. Understanding the reasons for this discrepancy may reveal insights into the complex relationship of genetic determinants of body weight in the etiology of breast cancer.Peer reviewe

Serum 25-Hydroxyvitamin D and Cancer Risk: A Systematic Review of Mendelian Randomization Studies

Epidemiological studies suggest that higher serum 25-hydroxyvitamin D is associated with lower risk for several cancers, including breast, prostate, colorectal, and lung cancers. To mitigate confounding, genetic instrumental variables (IVs) have been used to estimate causal associations between 25-hydroxivtamin D and cancer risk via Mendelian randomization (MR). We provide a systematic review of 31 MR studies concerning 25-hydroxyvitamin D and cancer incidence and mortality identified from biomedical databases. MR analyses were conducted almost exclusively in European-ancestry populations and identified no statistically significant associations between higher genetically predicted 25-hydroxyvitamin D and lower risk for total cancer or colorectal, breast, prostate, lung, or pancreatic cancers. In recent studies including ≥80 genetic IVs for 25-hydroxyvitamin D, null associations were reported for total cancer (odds ratio [95% confidence interval] per 1-standard deviation increase: 0.98 [0.93–1.04]), breast (1.00 [0.98–1.02]), colorectal (0.97 [0.88–1.07]), prostate (0.99 [0.98–1.01]), and lung cancer (1.00 [0.93–1.03]). A protective association was observed for ovarian cancer in the Ovarian Cancer Association Consortium (0.78 [0.63–0.96] per 20 nmol/L increase, p-trend = 0.03), but not in the UK Biobank (1.10 [0.80–1.51]). Null associations were reported for other tumor sites (bladder, endometrium, uterus, esophagus, oral cavity and pharynx, kidney, liver, thyroid, or neural cells). An inconsistent protective association for cancer-specific mortality was also observed. Results from MR analyses do not support causal associations between 25-hydroxyvitamin D and risk for cancer incidence or mortality. Studies including non-White populations may be valuable to understand low 25-hydroxyvitamin D as a modifiable risk factor in populations with a higher risk of common cancers, including African ancestry individuals

Prospective Cohort Study of Central Adiposity and Risk of Death in Middle Aged and Elderly Chinese.

Asians have high prevalence of central obesity despite the low prevalence of general obesity. We evaluated associations between the central obesity measure, waist-hip ratio (WHR) with total and cause-specific mortality in middle-aged and elderly Chinese participants. Data arise from two prospective population-based cohort studies: the Shanghai Men's Health Study involves 53,425 men (participation rate = 74.0%), age 40-74 at baseline, and the Shanghai Women's Health Study involves 63,017 women (participation rate = 92.7%), age 40-70 at baseline. Information on lifestyle factors and anthropometric measurements were taken at baseline interview. Vital status and causes of death were obtained via surveys and annual linkages to relevant Shanghai registries through December 31, 2011. After median follow-up time of 7.5 years for the Shanghai Men's Health Study and 13.2 years for the Shanghai Women's Health Study, there were 2,058 and 3,167 deaths, respectively. In models adjusted for BMI and other potential confounders, WHR was associated with all-cause mortality; hazard ratios (HRs) (95% confidence intervals) across the first to fifth quintile increased from 1 (Reference), 1.10 (0.95,1.27), 1.21 (1.04,1.41), 1.11 (0.96,1.30), to 1.42 (1.22,1.65) in men and from 1 (Reference), 1.10 (0.96,1.27), 1.11 (0.97,1.27), 1.20 (1.05,1.37), to 1.48 (1.30,1.69) in women. WHR had a stronger association with cardiovascular disease, with multivariate-adjusted HRs of 1.5 to 1.7 observed for the highest versus lowest quintile of WHR. Dose-response associations were also seen for cancer and other-cause deaths. Stratified analyses suggested a stronger association with mortality among normal weight (BMI <25) than over-weight (BMI ≥25) individuals. Positive associations with mortality were observed in subgroups defined by follow-up duration, comorbidity, age, smoking, and physical activity. Greater central adiposity is associated with increased mortality in Chinese adults, even among individuals with low BMI. Physicians and the public should be aware of central adiposity's independent effects on health

Racial Differences in Hepatocellular Carcinoma Incidence and Risk Factors among a Low Socioeconomic Population

The purpose of this study was to examine differences in risk factors associated with hepatocellular carcinoma (HCC) among White and African Americans from low socioeconomic backgrounds in the Southern Community Cohort Study (SCCS). The SCCS is a prospective cohort study with participants from the southeastern US. HCC incidence rates were calculated. Multivariable Cox regression was used to calculate HCC-adjusted hazard ratios (aHR) associated with known baseline HCC risk factors for White and African Americans, separately. There were 294 incident HCC. The incidence rate ratio for HCC was higher (IRR = 1.4, 95%CI: 1.1–1.9) in African Americans compared to White Americans. White Americans saw a stronger association between self-reported hepatitis C virus (aHR = 19.24, 95%CI: 10.58–35.00) and diabetes (aHR = 3.55, 95%CI: 1.96–6.43) for the development of HCC compared to African Americans (aHR = 7.73, 95%CI: 5.71–10.47 and aHR = 1.48, 95%CI: 1.06–2.06, respectively) even though the prevalence of these risk factors was similar between races. Smoking (aHR = 2.91, 95%CI: 1.87–4.52) and heavy alcohol consumption (aHR = 1.59, 95%CI: 1.19–2.11) were significantly associated with HCC risk among African Americans only. In this large prospective cohort, we observed racial differences in HCC incidence and risk factors associated with HCC among White and African Americans

Risk of cause-specific mortality according to waist-hip ratio stratified by body mass index, Shanghai, China, Shanghai Men’s Health Study 2002–2006, Shanghai Women’s Health Study 1996–2000.

<p>Hazard ratios for the associations between waist-hip ratio with cardiovascular disease, cancer and other-cause mortality, stratified by baseline body mass index. Point estimates are plotted on the logarithmic scale.</p