Yen-Ching Chen

Cancer and inflammation: Promise for biologic therapy

Cancers often arise as the end stage of inflammation in adults, but not in children. As such there is a complex interplay between host immune cells during neoplastic development, with both an ability to promote cancer and limit or eliminate it, most often complicit with the host. In humans, defining inflammation and the presence of inflammatory cells within or surrounding the tumor is a critical aspect of modern pathology. Groups defining staging for neoplasms are strongly encouraged to assess and incorporate measures of the presence of apoptosis, autophagy, and necrosis and also the nature and quality of the immune infiltrate. Both environmental and genetic factors enhance the risk of cigarette smoking, Helicobacter pylori, hepatitis B/C, human papilloma virus, solar irradiation, asbestos, pancreatitis, or other causes of chronic inflammation. Identifying suitable genetic polymorphisms in cytokines, cytokine receptors, and Toll-like receptors among other immune response genes is also seen as high value as genomic sequencing becomes less expensive. Animal models that incorporate and assess not only the genetic anlagen but also the inflammatory cells and the presence of microbial pathogens and damage-associated molecular pattern molecules are necessary. Identifying micro-RNAs involved in regulating the response to damage or injury are seen as highly promising. Although no therapeutic strategies to prevent or treat cancers based on insights into inflammatory pathways are currently approved for the common epithelial malignancies, there remains substantial interest in agents targeting COX2 or PPARγ, ethyl pyruvate and steroids, and several novel agents on the horizon.

Sex Steroid Hormones and the Androgen Receptor Gene CAG Repeat and Subsequent Risk of Prostate Cancer in the Prostate-Specific Antigen Era

Objective: Sex steroid hormones are thought to contribute to the growth, differentiation, and progression of prostate cancer. We investigated plasma levels of sex steroid hormones and length of the androgen receptor gene CAG repeat in relation to incident prostate cancer diagnosed in the prostate-specific antigen (PSA) era. Methods: Using a nested case-control design, we included 460 prostate cancer cases diagnosed after providing a blood specimen in 1993 but before February 1998 among men in the Health Professionals Follow-up Study. Controls were 460 age-matched men without prostate cancer who had a screening PSA test after the date of providing a blood specimen. We measured plasma concentrations of total testosterone, free testosterone, dihydrotestosterone, androstanediol glucuronide, estradiol, and sex hormone binding globulin (SHBG) and determined the length of the androgen receptor gene CAG repeat. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) of prostate cancer. Results: Mean concentrations of the sex steroids adjusted for SHBG, and mean CAG repeat length did not differ significantly between the prostate cancer cases and controls. No significant associations with total prostate cancer were detected for plasma total testosterone concentration (comparing highest versus lowest quartiles: OR, 0.78; 95% CI, 0.48-1.28; Ptrend = 0.73) or the other sex hormones after adjusting for SHBG. However, plasma total testosterone concentration was positively associated with low-grade disease (Gleason sum < 7: OR, 1.91; 95% CI, 0.89-4.07; Ptrend = 0.02) and inversely associated with high-grade disease (Gleason sum ≥ 7: OR, 0.26; 95% CI, 0.10-0.66; Ptrend = 0.01). Similar patterns for grade were observed for free testosterone. Short CAG repeat length was not associated with total prostate cancer (≤ 19 versus ≥ 24: OR, 0.84; 95% CI, 0.57-1.23; Ptrend = 0.22) or grade of disease. No clear associations with regionally invasive or metastatic (≥ T3b, N1, or M1) were found for any of the hormones or the CAG repeat, although the number of these cases was small. Conclusions: The overall lack of association of prostate cancer diagnosed in the PSA era with sex steroid hormones and the androgen receptor gene CAG repeat length is consistent with the hypothesis that these factors do not substantially contribute to the development of early prostate cancer in the PSA era. The influence of plasma total and free testosterone concentrations on prostate cancer grade merits further evaluation.

Arsenic methylation and bladder cancer risk in Taiwan

Objective: The mechanism of arsenic detoxification in humans remains unclear. Data are especially lacking for low-level arsenic exposure. We hypothesize that arsenic methylation ability, defined as the ratios of monomethylarsonic acid (MMA(V))/inorganic arsenic (primary arsenic methylation index, PMI) and dimethylarsinic acid (DMA(V))/MMA(V) (secondary arsenic methylation index, SMI), may modify the association between cumulative arsenic exposure (CAE, mg/L-year) and the risk of bladder cancer. In this study we investigated the relationship among arsenic methylation ability, CAE, and the risk of bladder cancer in a hospital-based case–control study in southwestern Taiwan. Methods: From January 1996 to December 1999 we identified 49 patients with newly diagnosed cases of bladder cancer at the National Cheng-Kung University (NCKU) Medical Center; controls consisted of 224 fracture and cataract patients selected from the same medical center. The levels of four urinary arsenic species: arsenite (As(III)), arsenate (As(V)), MMA(V), and DMA(V)) were determined in all subjects by using the high-performance liquid chromatography hydride-generation atomic absorption spectrometry (HPLC-HGAAS). CAE was estimated by using published data collected in a survey from 1974 to 1976. Results: Compared to a CAE ≦ 2 mg/L-year, CAE > 12 mg/L-year was associated with an increased risk of bladder cancer (multivariate odds ratio (OR) 4.23, 95% confidence interval (CI) 1.12–16.01), in the setting of a low SMI ( ≦ 4.8). Compared to women, smoking men (OR 6.23, 95% CI 1.88–20.62) and non-smoking men (OR 3.25, 95% CI 0.95–11.06) had higher risks of bladder cancer. Given the same level of PMI, smoking men (OR 9.80, 95% CI 2.40–40.10) and non-smoking men (OR 4.45, 95% CI 1.00–19.84) had a higher risk of bladder cancer when compared to women. With the same level of SMI, both smoking men (OR 6.28, 95% CI 1.76–22.39) and non-smoking men (OR 3.31, 95% CI 0.84–12.97) had a higher risk of bladder cancer when compared to women. Conclusions: Subjects with low SMI have a substantially increased risk of bladder cancer, especially when combined with high CAE levels.

Sequence Variants of Toll-Like Receptor 4 and Susceptibility to Prostate Cancer

Chronic inflammation has been hypothesized to be a risk factor for prostate cancer. The Toll-like receptor 4 (TLR4) presents the bacterial lipopolysaccharide (LPS), which interacts with ligand-binding protein and CD14 (LPS receptor) and activates expression of inflammatory genes through nuclear factor-kappaB and mitogen-activated protein kinase signaling. A previous case-control study found a modest association of a polymorphism in the TLR4 gene [11381G/C, GG versus GC/CC: odds ratio (OR), 1.26] with risk of prostate cancer. We assessed if sequence variants of TLR4 were associated with the risk of prostate cancer. In a nested case-control design within the Health Professionals Follow-up Study, we identified 700 participants with prostate cancer diagnosed after they had provided a blood specimen in 1993 and before January 2000. Controls were 700 age-matched men without prostate cancer who had had a prostate-specific antigen test after providing a blood specimen. We genotyped 16 common (>5%) single nucleotide polymorphisms (SNP) discovered in a resequencing study spanning TLR4 to test for association between sequence variation in TLR4 and prostate cancer. Homozygosity for the variant alleles of eight SNPs was associated with a statistically significantly lower risk of prostate cancer (TLR4_1893, TLR4_2032, TLR4_2437, TLR4_7764, TLR4_11912, TLR4_16649, TLR4_17050, and TLR4_17923), but the TLR4_15844 polymorphism corresponding to 11381G/C was not associated with prostate cancer (GG versus CG/CC: OR, 1.01; 95% confidence interval, 0.79-1.29). Six common haplotypes (cumulative frequency, 81%) were observed; the global test for association between haplotypes and prostate cancer was statistically significant (chi(2) = 14.8 on 6 degrees of freedom; P = 0.02). Two common haplotypes were statistically significantly associated with altered risk of prostate cancer. Inherited polymorphisms of the innate immune gene TLR4 are associated with risk of prostate cancer.

Risk Factors for Dementia

Dementia is a complex human disease. The incidence of dementia among the elderly population is rising rapidly worldwide. In the United States, Alzheimers disease (AD) is the leading type of dementia and was the fifth and eighth leading cause of death in women and men aged > or = 65 years, respectively, in 2003. In Taiwan and many other counties, dementia is a hidden health issue because of its underestimation in the elderly population. In Western countries, the prevalence of AD increases from 1-3% among people aged 60-64 years to 35% among those aged > 85 years. In Taiwan, the prevalence of dementia for people aged > or = 65 years was 2-4% by 2000. Therefore, it is important to identify protective and risk factors for dementia to prevent this disease at an early stage. Several factors are related to dementia, e.g. age, ethnicity, sex, genetic factors, physical activity, smoking, drug use, education level, alcohol consumption, body mass index, comorbidity, and environmental factors. In this review, we focus on studies that have evaluated the association between these factors and the risk of dementia, especially AD and vascular dementia. We also suggest future research directions for researchers in dementia-related fields.

Molecular epidemiology of cancer.

Epidemiology is very successful in identifying environmental and lifestyle factors that increase or reduce risk of specific cancers, leading to cancer prevention strategies. However, the etiology of many types of cancer is still poorly understood, despite extensive use of questionnaires and interview‐based approaches in conventional epidemiologic studies. The integration of molecular techniques into epidemiology studies may provide new insights and has been referred to as molecular epidemiology. For instance, our ability to make connections between lifestyle and cancer risk is limited by difficulty in accurately measuring exposure to many carcinogens—newer molecular markers of exposure may provide better information. The completion of the Human Genome Project gives us knowledge of the genetic variations that presumably underlie the fact that a family history of cancer is a risk factor for most cancer types. Some of this excess risk has been explained over the last decade by identification of mutations in genes that give rise to a very high familial risk. Molecular epidemiologists are searching for genes that may give rise to much smaller increases in individual risk, but account for much of the residual risk associated with family history. These genes may also interact with environment and lifestyle factors such that cancer risk is not equally elevated in all persons exposed to an environmental factor (but not genetically susceptible), or all gene carriers (but not exposed to the environmental factor). Molecular markers may help to differentiate tumors with the same histologic appearance into different etiologic subtypes. Finally, response to treatment may be determined by molecular subtypes of the tumor, or inherited variation in drug metabolism. Examples will be given of how use of molecular techniques is informative in epidemiological studies of cancer and is predicted to lead to improvements in cancer incidence, early detection, and mortality.

Arsenic Methylation, GSTT1, GSTM1, GSTP1 Polymorphisms, and Skin Lesions

Objective We investigated whether primary and secondary arsenic methylation ratios were associated with skin lesions and whether GSTT1, GSTP1, and GSTM1 polymorphisms modify these relationships. Methods A case–control study of 600 cases and 600 controls that were frequency matched on age and sex was conducted in Pabna, Bangladesh, in 2001–2002. Individual well water, urine, and blood samples were collected. Water arsenic concentration was determined using inductively coupled plasma mass spectrometry (ICP-MS). Urinary arsenic speciation was determined using high performance liquid chromatography hydride with generator atomic absorption spectrometry and ICP-MS. Genotyping was conducted using multiplex polymerase chain reaction and TaqMan. Results A 10-fold increase in primary methylation ratio [monomethylarsonic acid (MMA)/(arsenite + arsenate] was associated with a 1.50-fold increased risk of skin lesions (multivariate odds ratio = 1.50; 95% confidence interval, 1.00–2.26). We observed significant interaction on the multiplicative scale between GSTT1 wildtype and secondary methylation ratio [dimethylarsinic acid/MMA; likelihood ratio test (LRT), p = 0.01]. No significant interactions were observed for GSTM1 or GSTP1 or for primary methylation ratios. Conclusion Our findings suggest that increasing primary methylation ratios are associated with an increase in risk of arsenic-related skin lesions. The interaction between GSTT1 wildtype and secondary methylation ratio modifies risk of skin lesions among arsenic-exposed individuals.

Identification of methylated CpG motifs as inhibitors of the immune stimulatory CpG motifs

The unmethylated CpG motifs within E. coli DNA (EC) cause immune stimulation. In contrast, mammalian DNA such as calf thymus (CT) DNA had been thought to be immunologically inert. In this article, we demonstrate that CT DNA unexpectedly specifically inhibits the immune activation by EC but not that by endotoxin. This inhibitory effect was mediated in the signaling pathway activated by EC since CT DNA markedly inhibited the CpG-induced nuclear translocation of the transcription factors, NF-κB and AP-1. In addition, CT DNA significantly inhibited the synergistic immune activation by EC and endotoxin. The mechanism of the inhibition by CT DNA probably did not involve the inhibition of the cellular uptake of EC. Using a CpG-depleted plasmid, we demonstrated that CpG methylation played an important role in the inhibition by CT DNA. Compared with unmethylated plasmid DNA, CpG-methylated DNA inhibited the immune activation by EC to the same extent as did CT DNA. Importantly, the inhibitory effect of CT DNA was also observed in vivo. Our results suggest that methylated DNA may be applied to alleviate the unwanted immune stimulation and inflammation in systemic inflammatory response syndrome and in gene therapy with plasmid DNA.

Occurrence and Treatment of Suspected Pneumonia in Long-Term Care Residents Dying with Advanced Dementia

Objectives: To describe the occurrence and management of suspected pneumonia in end‐stage dementia and to identify factors associated with aggressiveness of antibiotic treatment.

Interaction between environmental tobacco smoke and arsenic methylation ability on the risk of bladder cancer.

AbstractObjective: Arsenic exposure and environmental tobacco smoke (ETS) have been suspected to be associated with bladder cancer risk. We hypothesize that interaction between ETS and the ability to methylate arsenic, a detoxification pathway, modifies the risk of bladder cancer. Methods: From January 1996 to December 1999, we identified 41 newly diagnosed bladder cancer patients and 202 fracture and cataract patients at the National Cheng-Kung University (NCKU) Medical Center. The levels of urinary arsenic species [As(III), As(V), MMA(V), and DMA(V)] were determined in all subjects. Results: We found significant interaction between ETS and secondary methylation index (SMI) on the risk of bladder cancer (p=0.02). Among non-smokers with a high primary methylation index (PMI), the risk of bladder cancer was lower in subjects exposed to ETS (OR, 0.37; 95% CI, 0.14–0.96) than in subjects without exposure to ETS. Among non-smokers without ETS, the risk of bladder cancer was 4.7 times higher in subjects with a low SMI (95% CI, 1.30–16.81) than in subjects with a high SMI. Conclusions: Ability to methylate arsenic plays an important role in reducing the risk of bladder cancer attributable to the continuation of arsenic exposure from drinking water and from ETS exposure.