Body mass index and oxidative DNA damage: a longitudinal study

Leanness has been shown to be related to an increased risk of some cancer forms, including lung cancer. However, biological evidence supporting a causal link between leanness and carcinogenesis is limited. The authors investigated longitudinally the association between body mass index (BMI) and levels of urinary 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage, using data from 174 healthy employees who participated in a lifestyle intervention study. 8-OHdG levels were measured using automated high-performance liquid chromatography and adjusted for urinary creatinine levels. Analysis of repeated measurements using a random effects model detected a statistically significant inverse association between BMI and 8-OHdG levels (P = 0.003); one unit decrease in BMI was associated with a 2.7% (95% confidence interval 0.9-4.4) increase in 8-OHdG levels. The association was pronounced among men consuming less than 20 cigarettes per day (8.8% increase per unit decrease in BMI) and among non-smoking men (3.7% increase). The results based on a longitudinal observation suggest that weight loss is associated with increased oxidative DNA damage, a state presumably related to an increased risk of cancer.     

Mutations of the epidermal growth factor receptor gene and related genes as determinants of epidermal growth factor receptor tyrosine kinase inhibitors sensitivity in lung cancer

Recent discovery of mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene in lung adenocarcinoma greatly stimulated biomarker research on predictive factors for EGFR tyrosine kinase inhibitors (TKI), such as gefitinib and erlotinib. Although patients with activating mutations of the EGFR generally respond to EGFR TKIs very well, it is natural to assume that there is no sole determinant, considering great complexity and redundancy of the EGFR pathway. Subsequently, roles of different types of EGFR mutations or mutations of genes that are members of the EGFR pathway such as KRAS and HER2 have been evaluated. In this review, we summarize the recent findings about how mutations of the EGFR and related genes affect sensitivity to EFGR-TKIs. We also discuss molecular mechanisms of acquired resistance to EGFR-TKIs that is almost inevitable in EGFR-TKI therapy. The door for genotype-based treatment of lung cancer is beginning to open, and through these efforts, it will be possible to slow the progression of lung cancer and eventually, to decrease mortality from lung cancer. ( Cancer Sci 2007; 98: 1817–1824)     

Lack of association between CpG island methylator phenotype in human gastric cancers and methylation in their background non-cancerous gastric mucosae

The presence of high levels of aberrant DNA methylation in gastric mucosae correlates with risk of gastric cancer. Some gastric cancers are known to have methylation of multiple CpG islands (CGI), which is referred to as the CGI methylator phenotype (CIMP). In the present study, we aimed to clarify the possible association between the CIMP in cancers and high methylation levels in their background mucosae by accurate quantitative methylation analysis of 14 carefully selected promoter CGI. Methylation levels were measured in 66 cancers and their background mucosae, along with 19 normal mucosae of healthy volunteers. Methylation in cancers was classified as absent (methylation level = 0%) or positive. The number of methylated CGI in a cancer showed a continuous distribution, and cancers were classified as CIMP high (21 cases), CIMP low (30 cases), or CIMP negative (15 cases). CIMP-high gastric cancer patients had significantly better survival rates than CIMP-negative patients. Of the Epstein–Barr virus-positive gastric cancers studied, eight out of nine presented as CIMP high. Methylation in background mucosae showed a unimodal distribution, and was assessed by their degree. The gastric mucosae of cancer patients showed higher levels than normal gastric mucosae of healthy volunteers. Finally, the CIMP-high, CIMP-low, and CIMP-negative statuses in cancers were not associated with methylation levels of individual genes and their means in the background mucosae. These showed that the CIMP statuses in gastric cancers had no association with methylation levels in the background gastric mucosae. ( Cancer Sci 2007; 98: 1853–1861)     

Evaluation of optimal drug concentration in histoculture drug response assay in association with clinical efficacy for head and neck cancer

Induction chemotherapy or concomitant chemoradiotherapy has been used increasingly to improve survival, organ preservation and function in patients with head and neck cancer (HNC). However, this regimen encounters significant side effects with potential adverse reactions causing many disadvantages for patients. Therefore, reliable chemosensitivity assays are needed to accurately predict the response to chemotherapy and guide the selection and treatment of patients with HNC. The main purpose of this study was to examine the optimal drug concentrations for evaluating in vitro chemosensitivity using the histoculture drug response assay (HDRA). The tested tumor specimens included 7 from oral cavities (14.3%), 12 from oropharynx (24.5%), 10 hypopharynx (20.4%), 3 larynx (6.1%), 5 sinonasal (10.2%), 2 salivary glands (4.1%), and 10 from metastatic lymph nodes (20.4%), respectively. Histopathologic types of all 49 specimens were squamous cell carcinoma. We investigated the optimal drug concentrations in HDRA searching at doses of 4-100 microg/ml for cisplatin and 60-1500 microg/ml for 5-FU. We considered the concentration of 20 microg/ml to be appropriate for evaluating cisplatin sensitivity in HNC among the tested dosages. As for cisplatin sensitivity in vitro, the 50% cut-off inhibition index (I.I.) was found to have a significant association with the clinical response to chemotherapy, with an accurate prediction rate of 77.8%. The HDRA shows a predictive value for chemosensitivity in HNC patients using the optimal drug concentration cut-off with this site specificity.     

Breast cancer in first-degree relatives and risk of lung cancer: assessment of the existence of gene sex interactions

BACKGROUND: Previous studies have shown the sex differences in lung cancer and the associations between estrogen-related genes and non-small cell lung cancer. In the present study, we assumed the existence of shared candidate genes that are common in lung and breast cancers, and examined whether women with a family history of breast cancer are at increased risk of lung cancer compared with men, especially adenocarcinoma, in a case-only study. METHODS: This case-only study was conducted based on the Lung Cancer Database Project at the National Cancer Center Hospital East. A total of 1566 patients with newly diagnosed primary lung cancer were consecutively recruited between 1999 and 2003. Information on their family history of cancer and smoking habit was obtained from a self-administered questionnaire. To assess an interactions between two factors, odds ratios for interaction (ORis) and 95% confidence intervals (CIs) were calculated by case-only contingency table. RESULTS: A statistically significant ORi was observed between a family history of breast cancer in first-degree relatives (parent and siblings, not including children) and the sex of a patient (ORi: 2.22, 95% CI: 1.02-4.81). A stratified analysis by histologic subtypes showed a statistically significant ORi only for adenocarcinoma (ORi: 3.27, 95% CI: 1.19-8.98). No other family history of cancer, such as stomach, colon and lung cancer, showed a statistically significant ORi. CONCLUSION: This study suggests the possibility of gene-sex interaction in lung cancer.     

Colorectal polypectomy and risk of colorectal cancer by subsite: the Fukuoka Colorectal Cancer study

BACKGROUND: Colorectal adenomas are well-established precursor lesions for colorectal cancer and removal of polyps is deemed to reduce the risk of colorectal cancer. However, benefit of colorectal polypectomy in routine practice is still uncertain. We therefore investigated subsite-specific risks of colorectal cancer in relation to history of colorectal polypectomy in a case-control study. METHODS: Both case patients and control subjects were residents aged 20-74 years in Fukuoka City and three adjacent areas. The case group comprised 840 patients undergoing surgery for a first diagnosis of colorectal cancer, while the control subjects were 833 residents who were selected in the community by two-stage random sampling. Past history of selected diseases, surgery and lifestyle factors were ascertained by in-person interview. Statistical adjustment was made for sex, 5-year age class, residence, smoking, alcohol drinking, physical activity, body mass index and parental history of colorectal cancer. RESULTS: Overall, 74 case patients (9%) and 85 control subjects (10%) reported a prior history of colorectal polyps, and 50 cases (6%) and 64 controls (8%) had a history of colorectal polypectomy. The adjusted odds ratio associated with colorectal polypectomy was 0.71 (95% confidence interval [CI] 0.48-1.06) for the overall risk of colorectal cancer. The corresponding values for cancer of the proximal colon, distal colon, and rectum were 1.68 (95% CI 0.98-2.88), 0.71 (95% CI 0.41-1.26) and 0.24 (95% CI 0.11-0.52), respectively. CONCLUSIONS: The findings indicate that colorectal polypectomy in current practice confers a decreased risk of rectal cancer and possibly of distal colon cancer.     

Dysregulated expression of HOX and ParaHOX genes in human esophageal squamous cell carcinoma

Homeobox genes function as master regulators in embryonic morphogenesis. We hypothesized that homeobox genes are essential to maintain tissue- or organ-specificity even in adult body and that the dysregulated expression of homeobox genes results in tumor development and progression. To better understand the roles of homeobox genes in development and progression of esophageal cancer, we analyzed the expression patterns of 39 HOX genes and 4 ParaHOX (CDX1, CDX2, CDX4 and PDX1) genes in esophageal squamous cell carcinoma (ESCC) and normal esophageal mucosa tissues. A total of 48 primary ESCC tissues and 7 normal esophageal mucosa tissues were resected from patients who underwent radical surgery without any preoperative chemotherapy or radiotherapy. The expression of HOX and ParaHOX genes were analyzed by a quantitative real-time RT-PCR method and immunohistochemistry. The expression levels of 24 HOX genes, CDX1, CDX2 and PDX1 were significantly higher in ESCC compared to normal mucosa (p<0.01, Mann-Whitney U test). The Immunohistochemical study revealed that HOXA5 and D9 proteins were more cytoplasmic in ESCC than normal mucosa cells. Our data indicate that the disordered expression of HOX and ParaHOX genes are involved in the development of ESCC or its malignancy.     

Early diagnosis of recurrent hepatocellular carcinoma with 18F-FDG PET after radiofrequency ablation therapy

The aim of this study was to evaluate the role of positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (18F-FDG) in the restaging of hepatocellular carcinoma (HCC) treated with radiofrequency ablation (RFA). This study was performed on 33 lesions in 24 patients with HCC. 18F-FDG PET and computed tomography (CT) studies were performed in all patients before treatment. PET acquisition was started 50-60 min after injection of 18F-FDG (5-6 MBq/kg). Semi-quantitative analysis using Standardized Uptake Value (SUV) was measured for the evaluation of tumour 18F-FDG uptake. All patients underwent RFA treatment and were followed up at least 2 years with 18F-FDG PET, CT and clinical evaluation in the interval of every 3 months in the first year and every 6 months in the second year. 18F-FDG PET detected recurrence earlier than CT between 4-6 months in 2 patients and between 7-9 months in 6 patients whereas CT was positive in 4 patients. Overall detection rate of recurrence with 18F-FDG PET was 92% which was higher than that of CT (75%). Statistically significant difference in the SUV was observed between well and moderately differentiated HCC (p=0.033) and also between well and poorly differentiated HCC (p=0.037). The size of tumours showed a significant correlation with the time of recurrence (p<0.00033, r=0.8601, n=12). The results of this study indicate that 18F-FDG PET could detect recurrence earlier in patients with HCC treated with RFA, as compared with CT and could diagnose extrahepatic lesions. SUV showed a significant correlation with time of recurrence after RFA. 18F-FDG PET may be a dominant imaging modality as a follow-up procedure of HCC after RFA, in terms of early detection of recurrence.     

Early development of histiocytic sarcomas in p53 knockout mice treated with N-bis(2-hydroxypropyl)nitrosamine

p53 knockout mice have been utilized for the functional analysis of p53 in carcinogenic processes and for the evaluation of the carcinogenic potential of chemicals. In this study, we established that p53 knockout mice have an elevated susceptibility to the induction of histiocytic sarcoma (HS) by N-bis(2-hydroxy-propyl)nitrosamine (BHP). p53 heterozygous (+/-) and wild-type (+/+) mice were treated with 20 or 200 ppm BHP in their drinking water for 15 weeks or with 20 ppm BHP for 40 weeks. An additional group of p53 nullizygous (-/-) mice were treated with 20 ppm BHP for 15 weeks. In a 15-week experiment, hepatic HSs were unexpectedly observed in BHP-treated p53 (-/-) mice (30.8%) but not in p53 (+/-) and (+/+) mice and untreated (-/-) mice, indicating that a complete loss of p53 dramatically accelerates the genesis of HS. In a 40-week experiment, HSs were significantly increased in female p53 (+/-) mice (37.5%) as compared with female (+/+) mice (5.0%). Additionally, PCR-SSCP and sequencing analysis revealed a high frequency of p53 gene mutations in HSs, demonstrating the involvement of p53 gene mutations in HS development. Our data add to the understanding of the carcinogenic susceptibility of p53 knockout mice, and may help to elucidate the pathogenesis of HS development.     

Application of the two-layer method on pancreas digestion results in improved islet yield and maintained viability of isolated islets

BACKGROUND: Oxygenation of the pancreas during preservation by the two-layer method (TLM) has shown beneficial effects in islet transplantation. Here, we apply this concept (oxygenation) to the isolation process. METHODS: Rat pancreases were digested using four different methods. Pancreases were digested with preoxygenated perfluorocarbon (PFC) in group 2 and without it in group 1. Additionally, adenosine was included in the collagenase solution in subgroups B but not in subgroups A. Islet yields and viability were compared between groups. RESULTS: Tissue oxygen tension in group 1 was essentially zero during digestion, but rapidly reached around 300 mm Hg and was maintained in group 2. The tissue adenosine triphosphate (ATP) level in rat pancreas just after laparotomy (control) was 4.2+/-0.7 micromol/g dry weight; after digestion, it was 0.12+/-0.03 micromol/g, 0.70+/-0.10 micromol/g, 0.30+/-0.18 micromol/g, and 2.90+/-0.80 micromol/g in groups 1A, 1B, 2A, and 2B, respectively. No significant differences were observed between group 2B and control (P=0.19). Islet yields (IEQ/pancreas) were 1600+/-400, 1400+/-400, 1300+/-400, and 2400+/-100 in groups 1A, 1B, 2A, and 2B, respectively. The islet yield of group 2B was significantly higher than other groups (P<0.05). The cure rate after transplanting 200 islets into athymic nude mice did not differ (80% in all groups). The stimulation indices in the four groups were also the same. CONCLUSIONS: Tissue ATP levels after digestion were well maintained using TLM with adenosine digestion method. Consequently, greater numbers of islets could be retrieved. The new method was at least equivalent to islet function isolated by conventional method. Clinical study is therefore warranted.