Yun-Ling Zheng

Bleomycin-induced chromosome breaks as a risk marker for lung cancer: a case-control study with population and hospital controls

Environmental exposure to carcinogens and individual susceptibility play significant roles in cancer risk. Suboptimal DNA repair capability, measured by quantifying mutagen-induced chromosome breaks, might explain variable host susceptibility to environmental carcinogens. In an ongoing lung cancer case-control study, we compared individual sensitivity to bleomycin-induced chromosome breaks in 152 non-small cell lung cancer patients with 94 population controls and 85 hospital controls with no history of cancer. Mutagen sensitivity was measured by mean number of chromatid breaks per cell in cultured peripheral blood lymphocytes treated with bleomycin. Non-parametric tests and chi(2) tests were used to determine the statistical significance of the crude case-control comparisons, followed by logistic regression to adjust for important covariates. The mean number of bleomycin-induced breaks per cell was 1.01 for the cases compared with 0.86 for hospital controls (P < 0.01) and 0.89 for population controls (P < 0.01). The mean number of breaks per cell was 1.01 for those >65 years old and 0.81 for those < or = 65 years old (P < 0.01) among population controls. Defining bleomycin sensitive as >0.84 break/cell (the median level in population controls), 67% of the cases were bleomycin sensitive compared with 49% of the hospital controls [adjusted odds ratio (OR) = 2.69, 95% confidence interval (CI) = 1.44, 5.04], and 51% of the population controls (adjusted OR = 2.18, 95% CI = 1.13, 4.21). Our data indicate that the increased number of bleomycin-induced chromosome breaks was significantly associated with an increased risk of lung cancer in the first 331 subjects.

MicroRNA-9 as Potential Biomarker for Breast Cancer Local Recurrence and Tumor Estrogen Receptor Status

MicroRNAs (miRs) are small, non-protein coding transcripts involved in many cellular functions. Many miRs have emerged as important cancer biomarkers. In the present study, we investigated whether miR levels in breast tumors are predictive of breast cancer local recurrence (LR). Sixty-eight women who were diagnosed with breast cancer at the Lombardi Comprehensive Cancer Center were included in this study. Breast cancer patients with LR and those without LR were matched on year of surgery, age at diagnosis, and type of surgery. Candidate miRs were identified by screening the expression levels of 754 human miRs using miR arrays in 16 breast tumor samples from 8 cases with LR and 8 cases without LR. Eight candidate miRs that showed significant differences between tumors with and without LR were further verified in 52 tumor samples using real-time PCR. Higher expression of miR-9 was significantly associated with breast cancer LR in all cases as well as the subset of estrogen receptor (ER) positive cases (p = 0.02). The AUCs (Area Under Curve) of receiver operating characteristic (ROC) curves of miR-9 for all tumors and ER positive tumors are 0.68 (p = 0.02) and 0.69 (p = 0.02), respectively. In ER positive cases, Kaplan-Meier analysis showed that patients with lower miR-9 levels had significantly better 10-year LR-free survival (67.9% vs 30.8%, p = 0.02). Expression levels of miR-9 and another miR candidate, miR-375, were also strongly associated with ER status (p<0.001 for both). The potential of miR-9 as a biomarker for LR warrants further investigation with larger sample size.

Serum estrogen and tumor-positive estrogen receptor-alpha are strong prognostic classifiers of non-small-cell lung cancer survival in both men and women

The role of tumor estrogen receptors (ERs) and serum estrogen in lung cancer is inconclusive. We investigated the hypothesis that ERs and functional single-nucleotide polymorphisms in the estrogen biosynthesis pathway are associated with poorer lung cancer survival. Lung cancer patients (n = 305) from a National Cancer Institute-Maryland (NCI-MD) case-case cohort in the Baltimore metropolitan area were used as a test cohort. To validate, 227 cases from the NCI-MD case-control cohort and 293 cases from a Norwegian lung cancer cohort were studied. Information on demographics, tobacco and reproductive histories was collected in an interviewer-administered questionnaire. Serum estrogen, progesterone, tumor messenger RNA expression of hormone receptors and germ line DNA polymorphisms were analyzed for associations with lung cancer survival. Patients in the highest tertile of serum estrogen had worse survival in all three cohorts (P combined < 0.001). Furthermore, the variant allele of estrogen receptor alpha (ER-α) polymorphism (rs2228480) was significantly associated with increased tumor ER-α levels and worse survival in all three cohorts [hazard ratio (HR) = 2.59, 95% confidence interval (CI): 1.20- 4.01; HR = 1.76, 95% CI: 1.08-2.87 and HR = 2.85, 95% CI: 1.31-4.36). Other polymorphisms associated with lower serum estrogen correlated with improved survival. Results were independent of gender and hormone replacement therapy. We report a significant association of increased serum estrogen with poorer survival among lung cancer male and female patients. Understanding the genetic control of estrogen biosynthesis and response in lung cancer could lead to improved prognosis and therapy.

Telomere deficiencies on chromosomes 9p, 15p, 15q and Xp: potential biomarkers for breast cancer risk

Although telomere dysfunction is a characteristic of breast cancer cells, the relationship between deficiency on individual chromosomal telomeres in normal somatic cells and breast cancer risk has not been characterized. A case-control study was conducted to examine the associations between individual lengths of 92 telomeres in the human genome and the risk of breast cancer in 204 newly diagnosed breast cancer patients and 236 healthy controls. Chromosome arm-specific telomere lengths were measured by telomere quantitative fluorescent in situ hybridization. Unconditional logistic regression was used to estimate the risk associations. This genome-wide screen identified that shorter telomere lengths on chromosomes Xp and 15p were associated with breast cancer risk in pre-menopausal women, with adjusted odds ratios (aORs) of 2.5 (95% CI = 1.3, 4.8) and 2.6 (1.3, 5.0), respectively. The study also revealed that greater length differences between homologous telomeres on chromosomes 9p, 15p and 15q were associated with breast cancer risk in pre-menopausal women, with aORs of 4.6 (2.3, 9.2), 3.1 (1.6, 6.0) and 2.8 (1.4, 5.4), respectively. When the subjects were categorized into quartiles, a dose-response relationship was observed for all of the above telomeres (P-for-trend ≤ 0.005). This study revealed that telomere deficiencies on chromosomes 9p, 15p, 15q and Xp were associated with breast cancer risk in pre-menopausal women. If confirmed in future studies, chromosomal arm-specific telomeres are likely to be a useful panel of blood-based biomarkers for breast cancer risk assessment, given their strong associations with breast cancer risk.

Elevated lung cancer risk is associated with deficiencies in cell cycle checkpoints: genotype and phenotype analyses from a case-control study

Cell cycle checkpoints play critical roles in the maintenance of genomic integrity and inactivation of checkpoint genes are frequently perturbed in most cancers. In a case‐control study of 299 non‐small cell lung cancer cases and 550 controls in Baltimore, we investigated the association between γ‐radiation‐induced G2/M arrest in cultured blood lymphocytes and lung cancer risk, and examined genotype‐phenotype correlations between genetic polymorphisms of 20 genes involving in DNA repair and cell cycle control and γ‐radiation‐induced G2/M arrest. The study was specifically designed to examine race and gender differences in risk factors. Our data indicated that a less efficient DNA damage‐induced G2/M checkpoint was associated with an increased risk of lung cancer in African American women with an adjusted odds ratio (OR) of 2.63 (95% CI = 1.01–7.26); there were no statistically significant associations for Caucasians, or African American men. When the African American women were categorized into quartiles, a significant reverse trend of decreased G2/M checkpoint function and increased lung cancer risk was present, with lowest‐vs.‐highest quartile OR of 13.72 (95% CI = 2.30–81.92, ptrend < 0.01). Genotype‐phenotype correlation analysis indicated that polymorphisms in ATM, CDC25C, CDKN1A, BRCA2, ERCC6, TP53, and TP53BP1 genes were significantly associated with the γ‐radiation‐induced G2/M arrest phenotype. This study provides evidence that a less efficient G2/M checkpoint is significantly associated with lung cancer risk in African American women. The data also suggested that the function of G2/M checkpoint is modulated by genetic polymorphisms in genes involved in DNA repair and cell cycle control.

Chromosome 9 arm-specific telomere length and breast cancer risk.

BACKGROUND Telomere dysfunction is involved in the development of breast cancer and very short telomeres are frequent genetic alterations in breast tumors. However, the influence of telomere lengths of specific chromosomal arms on the breast cancer risk is unknown. METHODS We conducted a case-control study of breast cancer to examine the associations of the telomere length on chromosome 9 short arms (9p) and long arms (9q) with risk of breast cancer. Chromosome 9 arm-specific telomere lengths were measured by quantitative fluorescent in situ hybridization using cultured blood lymphocytes. RESULTS Telomere length on chromosome 9p was significantly shorter in breast cancer patients than in control subjects (P < 0.001). Using the 50th percentile value in controls as a cut point, women who have short 9p telomeres had an increased risk of breast cancer [adjusted odds ratio (OR) = 2.6; 95% confidence interval (CI) = 1.5-4.3]. When the 9p telomere length was divided into quartiles, a significant inverse dose-response relationship between 9p telomere length and breast cancer risk was observed (P(trend) < 0.001), with a quartile ORs of 3.0 (95% CI = 1.2-7.5), 3.9 (95% CI = 1.6-9.5) and 6.6 (95% CI = 2.8-15.9) for third, second and first quartile, respectively, when compared with women in the fourth quartile. CONCLUSIONS Short telomere length on chromosome 9p is strongly associated with the risk of breast cancer. If confirmed by future studies, chromosome 9p telomere length has the potential to be incorporated into the current prediction models to significantly enhance breast cancer risk prediction.

Prevention of Lipid Peroxidation–derived Cyclic DNA Adduct and Mutation in High-Fat Diet–induced Hepatocarcinogenesis by Theaphenon E

Obesity is associated with cancer risk and its link with liver cancer is particularly strong. Obesity causes non-alcoholic fatty liver disease (NAFLD) that could progress to hepatocellular carcinoma (HCC). Chronic inflammation likely plays a key role. We carried out a bioassay in the high-fat diet (HFD)-fed C57BL/6J mice to provide insight into the mechanisms of obesity-related HCC by studying γ-OHPdG, a mutagenic DNA adduct derived from lipid peroxidation. In an 80-week bioassay, mice received a low-fat diet (LFD), high-fat diet (HFD), and HFD with 2% Theaphenon E (TE) (HFD+TE). HFD mice developed a 42% incidence of HCC and LFD mice a 16%. Remarkably, TE, a standardized green tea extract formulation, completely blocked HCC in HFD mice with a 0% incidence. γ-OHPdG measured in the hepatic DNA of mice fed HFD and HFD+TE showed its levels increased during the early stages of NAFLD in HFD mice and the increases were significantly suppressed by TE, correlating with the tumor data. Whole-exome sequencing showed an increased mutation load in the liver tumors of HFD mice with G>A and G>T as the predominant mutations, consistent with the report that γ-OHPdG induces G>A and G>T. Furthermore, the mutation loads were significantly reduced in HFD+TE mice, particularly G>T, the most common mutation in human HCC. These results demonstrate in a relevant model of obesity-induced HCC that γ-OHPdG formation during fatty liver disease may be an initiating event for accumulated mutations that leads to HCC and this process can be effectively inhibited by TE. Cancer Prev Res; 11(10); 665–76. ©2018 AACR.

Urinary Bladder Cancer in Egypt: Are There Gender Differences in Its Histopathological Presentation?

We investigated gender differences in the histopathologic presentation of bladder cancer cases in Egypt, where both urothelial cell carcinoma (UC) and squamous cell carcinoma (SCC) types are highly prevalent. We used logistic regression to estimate the unadjusted (OR) and adjusted odds ratio (AOR) and 95% confidence interval (CI) of the associations between gender and different histopathologic and sociodemographic parameters of 2,186 confirmed cases of primary bladder cancer (1,775 males and 411 females; 784 SCC and 1,402 UC). There were no statistically significant gender differences in tumor grade, stage, mucosal ulcer, or inflammatory cystitis, regardless of the cancer type, but men were less likely than women to have undergone cystectomy with pelvic lymphadenectomy. Having Schistosoma haematobium (SH) ova in the bladder tissue was significantly associated with male gender in the fully adjusted model of either SCC (AOR (95% CI) = 2.12 (1.15–3.89)) or UC cases (3.78 (1.89–7.55)). Compared to females, male cases were significantly older at time of diagnosis and smokers. In Egypt, regardless of the type of bladder cancer (SCC or UC), male more than female cases had evidence of SH infection, but not other histopathologic differences, in bladder tissue specimens.

Abstract C22: Telomere length variation and frequency of short telomeres in blood lymphocytes: Novel biomarkers for lung cancer risk

Background: Although it is widely recognized that telomere dysfunction plays an important role in cancer, the relationship between telomere function in somatic cells and lung cancer risk is not well defined. In a case-control study of non-small cell lung cancer, we examined relationship between several key telomere features and lung cancer risk. Method: Telomere fluorescent in situ hybridization was used to measure telomere features using short-term cultured blood lymphocytes. Logistic regression was used to estimate the strength of association between telomere features and lung cancer risk. Results: Telomere length variation across all chromosomal ends was significantly associated with lung cancer risk, with adjusted odds ratios of 4.67 [95% confidence interval (CI) = 1.46 – 14.9] and 0.46 (95% CI = 0.25 – 0.84) for young (age 60) individuals, respectively. Similar strength and direction of associations between percentage of short telomeres and lung cancer risk were also observed. Telomere length variation and average telomere length jointly affect lung cancer risk. When comparing individuals with short telomere and high telomere length variation to those with long telomere and low telomere length variation, adjusted odd ratios were 8.21 (95% CI = 1.71 – 39.5) and 0.33 (95% CI = 0.15 – 0.72) for young and old individuals, respectively. Conclusion: Telomere length variation and percentage of short telomeres in blood lymphocytes are significantly associated with lung cancer risk and the associations are modulated by age. Telomere length variation in combination with average telomere length may be a promising tool for lung cancer risk assessment. Citation Format: Bing Sun, Ying Wang, Krishna Kota, Yaru Shi, Salaam Motlek, Kepher Makambi, Christopher A. Loffredo, Peter G. Shields, Qin Yang, Curtis C. Harris, Yun-Ling Zheng. Telomere length variation and frequency of short telomeres in blood lymphocytes: Novel biomarkers for lung cancer risk. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr C22.

Abstract 3817: Chromosome specific telomeres and breast cancer risk

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Although telomere dysfunction is a characteristic of breast cancer cells, the relationship between deficiency on individual chromosomal telomeres in normal somatic cells and breast cancer risk has not been characterized. A case-control study was conducted to examine the associations between individual lengths of 92 telomeres in the human genome and the risk of breast cancer in 204 newly diagnosed breast cancer patients and 236 healthy controls. Chromosome arm-specific telomere lengths were measured by telomere quantitative fluorescent in situ hybridization (TQ-FISH). Unconditional logistic regression was used to estimate the risk associations. This genome-wide screen identified that shorter telomere lengths on chromosome Xp and 15p were associated with breast cancer risk in premenopausal women, with adjusted odds ratios (aOR) of 2.5 (95% CI = 1.3, 4.8), and 2.6 (1.3, 5.0), respectively. The study also revealed that greater length differences between homologous telomeres on chromosome 9p, 15p and 15q were associated with breast cancer risk in premenopausal women, with aORs of 4.6 (2.3, 9.2), 3.1 (1.6, 6.0), and 2.8 (1.4, 5.4) respectively. When the subjects were categorized into quartiles, a dose response relationship was observed for all of the above telomeres (P-for-trend < 0.005). This study revealed that telomere deficiencies on chromosome 9p, 15p, 15q and Xp were associated with breast cancer risk in premenopausal women. If confirmed in future studies, chromosomal arm-specific telomeres are likely to be a useful panel of blood-based biomarkers for breast cancer risk assessment, given their strong associations with breast cancer risk. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3817. doi:10.1158/1538-7445.AM2011-3817