Fluorescentin situ hybridization assessment of chromosome 8 copy number in breast cancer

Summary Conventional cytogenetics of breast and other solid tumors has been hampered by a number of factors. An analysis of breast tumor tissues was therefore undertaken using fluorescentin situ hybridization (FISH). A total of 34 specimens were analyzed using a chromosome 8-specific -satellite probe. Various approaches were tested and compared. Among 30 informative samples, 11 infiltrating ductal carcinomas, not otherwise specified (NOS), 5 ductal carcinomasin situ, 5 lobular carcinomas, 3 papillary carcinomas, and 6 benign lesions were studied. Of the 11 cases of infiltrating ductal carcinomas (NOS) analyzed, four cases showed 3 signals, one case showed 4 signals, and the rest showed 2 signals. Of the 5 cases of ductal carcinomain situ samples, 1 showed 3 signals and the other 4 cases showed 2 signals. All cases of lobular carcinomas, papillary carcinomas, and benign lesions showed 2 signals. We inferred from these data that 36% of the infiltrating ductal carcinomas (NOS) were trisomic and 9% were tetrasomic, whereas 20% of the ductal carcinomasin situ were trisomic. All samples from lobular carcinomas, papillary carcinomas, and the benign lesions were disomic. From our preliminary data, it can further be concluded that a subset of breast cancer is characterized by chromosome 8 trisomy. These data are consistent with an ever-increasing database on the association of chromosomal 8 trisomy with other cancers such as leukemia, lymphoma, prostate cancer, ovarian carcinoma, salivary gland tumor, malignant melanoma, desmoid tumors, and recently gestational trophoblastic disease. It is also noted that the ability to analyze formalin-fixed, paraffin-embedded archival material will enable a more comprehensive cytogenetic study of breast cancer than is currently available.     

Genetic Polymorphisms of eNOS, Hormone Receptor Status, and Survival of Breast Cancer

The endothelial cell-specific form of nitric oxide synthase (eNOS) may play an important role in tumor progression via angiogenesis or apoptosis. We studied eNOS −786T > C and 894G > T (Glu298Asp), two functionally significant SNPs, in relation to hazard of breast cancer recurrence or death in 873 women with incident, non-metastatic breast cancer, recruited from two teaching hospitals in Seoul, Korea, 1995–2002. Hazards were estimated by Cox proportional hazard models, in relation to genotype, adjusting for hormone receptor status, lymph node involvement, and tumor size. Women carriers of the eNOS −786C allele had significantly increased hazards of breast cancer recurrence or death, compared with women having the TT genotype (HR = 2.1, 95% CI = 1.03–4.33); risks increased up to 3-fold in ER positive cases (HR = 3.2, 95% CI = 0.95–10.50). The hazard was also increased in eNOS 894T carriers, however, it did not reach statistical significance (HR = 1.8, 95% CI = 0.85–3.93). The combined genotypes containing −786C or 894T was associated with a 2.5-fold risk, compared to the TT–GG genotypes, the most dominant genotype combination (95% CI = 1.29–4.68), with the greatest risks in ER positive cases (HR = 4.9, 95% CI = 1.31–18.36). These results indicate that the eNOS −786C polymorphism, and possibly the 894T polymorphism, are associated with breast cancer recurrence and death, particularly in women with ER positive tumors.     

Human papillomavirus,Chlamydia trachomatis, and other risk factors associated with cervical cancer in China

Background High prevalences of human papillomavirus (HPV) andChlamydia trachomatis infections, and their association with cervical cancer, have been reported in some parts of China. Other factors, including pregnancy and smoking, are reported to be associated with cervical cancer worldwide. Methods To determine significant risk factors for cervical cancer, we performed a case-control study in 43 women with cervical cancer and 370 women with normal findings from cervical cytologic analysis (controls), in the northeast of China. Scraped cervical cell samples were collected for examination of HPV andC. trachomatis DNA, using a polymerase chain reaction-based method for detection of low cancer risk and high cancer risk HPVs. Results Thirty-four of 370 controls, and 30 of 43 women with cervical cancer, were positive for HPV. None of the low-cancer risk HPV types were detected; HPV 16 was the predominant type in cervical cancers. The prevalence of HPV infection between pregnant and nonpregnant women did not differ, nor did it change over the course of pregnancy. The prevalence ofC. trachomatis infection was higher in HPV-positive than in HPV-negative control women, however, it did not differ between women with cervical cancer and the control group. Multivariate logistic analysis showed that neitherC. trachomatis infection, age at marriage, length of marriage, pregnancy, nor smoking were associated with cervical cancer. Conclusion Infection with HPV 16, 31, 33, or 58 was a significant risk determinant for cervical cancer, whereasC. trachomatis infection and other factors did not increase the risk of cervical cancer.     

Chromosome 8 numerical aberrations in stage II invasive ductal carcinoma

Aberrations in chromosome 8 are common in breast cancer. However, the relationship between numerical aberrations of chromosome 8 and clinical behavior (especially prognosis) in breast cancer is not well understood. In this study, a total of 40 specimens of stage II invasive ductal carcinomas (IDCs) was analyzed by fluorescence in situ hybridization (FISH) with a chromosome 8 centromere-specific probe and DNA flow cytometry (stage II_A: 20 cases; stage II_B: 20 cases). All cases were followed for at least 5.7 yr (mean: 7.5 yr; median: 7.7 yr) after surgery or until death. Single (loss), double, and triple or more signals (gain) of chromosome 8 were found in 7.6±3.5% (range: 2–16%; median: 7%), 53.7±13.2% (range: 25–81%, median: 53%), and 38.7±13.2% (range: 17–65%, median: 38%), respectively, of tumors. The frequencies of chromosome 8 gain and disomy correlated with patient outcome (respectively p<0.05 and p<0.01). When median ratios of chromosome 8 loss, disomy, and gain were used as the cutoff values, the survival curves revealed that patients in the low-frequency group survived significantly longer than those in the high-frequency group for chromosome 8 gain (p<0.05), and patients in the high-frequency group survived significantly longer than those in the low-frequency group for chromosome 8 disomy (p<0.05). Poor prognosis was not associated with age, tumor size, lymph node metastasis, histologic type, TNM stage, estrogen-receptor status, progesterone-receptor status, or DNA ploidy. Our results suggest that the frequencies of chromosome 8 gain and disomy is a potentially useful parameter for predicting prognosis of stage II IDCs.     

Combined effect of GSTM1, GSTT1, and COMT genotypes in individual

Our previous studies suggested that both catechol O-methyl transferase (COMT) and glutathione S-transferase (GST) M1 and T1 genotypes are associated with breast cancer risk. Here we extended the studies to evaluate the potential combined effect of these genotypes in individual breast cancer risk. Incident breast cancer cases (n = 202) and controls (n = 299) with no previous cancer were recruited from three teaching hospitals in Seoul in 1996-1999. Information on putative risk factors was collected by interviewed questionnaire. PCR-based methods were used for the genotyping analyses. Odds ratios (ORs) and 95% confidence (CIs) intervals were estimated by unconditional logistic regression after adjustment for known or suspected risk factors of breast cancer. Among pre-menopausal women the low activity associated (COMT *L) allele containing genotypes and the GSTM1 null genotype posed increased risks of breast cancer with ORs of 1.7 (95% CI = 1.0 - 2.8) and 1.7 (95% CI = 1.0-2.8), respectively. A marginally significant effect of GSTT1 null genotype was also observed when the total study population was considered (OR = 1.3, 95% CI = 1.0-2.1). When the combined genotype effects were examined, the concurrent lack of GSTM1 and GSTT1 genes posed a more than 2-fold risk of breast cancer (OR = 2.2, 95% CI = 1.2-3.9); this effect was mainly attributable in pre-menopausal women (OR = 3.2, 95% CI = 1.5-7.2). Moreover, the breast cancer risk increased in parallel with the number of COMT, GSTM1, and GSTT1 at-risk genotypes (p for trend = 0.003). This association was particularly clear in pre-menopausal women among whom combination of all three high-risk genotypes posed a 4.1-fold breast cancer risk (95% CI = 1.4-12.7) compared with pre-menopausal women without at-risk genotypes (p for trend = 0.001). The trend was more pronounced in women with BMI greater than 22 kg/m² (p for trend<0.001) and high-risk status of parity factor (nulliparous or women with the first full term pregnancy at age of over 25-year-old) (p for trend = 0.013). These results suggest the combined effect between reproductive factors and GSTM1, GSTT1 andCOMT genotypes in human breast carcinogenesis.     

<Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection,but not genetic polymorphism of CYP2E1, is highly prevalent in gastric cancer patients younger than 40 years

Background Gastric cancers in young adults are thought to be associated with risk factors that include Helicobacter pylori infection and genetic polymorphism. The objective of this study was to elucidate the roles of these risk factors in patients younger than 40 years by analyzing clinicopathological data and H. pylori infection, and using molecular epidemiologic techniques. Methods Clinicopathological features, the presence of H. pylori infection, endoscopic characteristics of gastritis, genetic polymorphism of P4502E1 (CYP2E1), and family history of cancer in patients with gastric cancer treated surgically at Nippon Medical School Hospital from 1991 to 2004 were analyzed, based on our medical database. Results Gastric cancer in those younger than 40 years was characterized by a predominance of female patients with poorly differentiated adenocarcinoma who had undergone total gastrectomy with extended lymphadenectomy. H. pylori infection had a higher prevalence in patients with gastric cancer than in patients with normal endoscopic results or chronic gastritis, especially in those younger than 40 years (odds ratio, 13.7). Atrophic gastritis, nodular gastritis, and rugal hyperplastic gastritis were observed by endoscopy as H. pylori-associated gastritis. No difference in the incidence of either CYP2E1 genetic polymorphism or a family history of cancer was observed among different age groups. Conclusion Gastric cancer in patients younger than 40 years is closely associated with H. pylori infection, but not with genetic characteristics. Eradication therapy for H. pylori and endoscopic examination of H. pylori-positive young adults may be anticipated to be adopted as a strategy for the prevention and/or early detection of cancer.     

Immunohistochemical expression of N-ras oncogene is a late event in head and neck carcinomas

This study investigated the expression of the N-ras oncogene in routinely processed tissue sections from 133 patients with squamous cell carcinoma of the head and neck (SCCHN) by immunohistochemistryusing anti-N-ras monoclonal antibody. N-ras expression was present in 67 of 133 (49.67%) cases. There was a highly significant correlation between N-ras expression and clinical stage of disease (P=0.003). This study confirmed that overexpression of the N-ras oncogene is common in SCCHN and that it may be an important event in the late stage of disease.     

Hereditary breast cancer: pathobiology, clinical translation, and potential for targeted cancer therapeutics

BRCA1 and BRCA2 breast cancers have distinct biological features as evidenced by histopathologic, immunohistochemical, gene expression profiling, and array-comparative genomic hybridization data. BRCA1 breast cancers may have a worse prognosis but may, however be amenable to treatment such as chemotherapy for small high-grade, lymph node negative breast cancers. Paradoxically, tamoxifen may provide effective adjuvant and chemopreventive therapy despite the predominantly negative estrogen receptor status of BRCA1 breast cancers. The distinctive biology of BRCA1 and BRCA2 breast cancers bodes well for the development of targeted cancer therapies. Cells with BRCA1 or BRCA2 loss of function are deficient in DNA double strand break repair and are sensitized to poly(ADP-ribose) polymerase (PARP) inhibitors, causing the persistence of DNA lesions which are usually repaired by homologous recombination and ultimately leading to apoptosis. The potentially high efficacy and low toxicity of poly(ADP-ribose) polymerase inhibitors presents an opportunity for targeted cancer therapeutics for BRCA1 and BRCA2 germline mutation carriers. Genotype-tailored chemoprevention may be feasible which could theoretically eliminate single cells that have sustained a second hit, before cancer progression takes place. If targeted cancer therapies emerge, it will become crucially important to identify BRCA carriers at the time of diagnosis for optimal therapy and to identify unaffected carriers for chemoprevention. If so, then to the extent that barriers in the recognition and referral of patients to genetic counseling cannot be surmounted, pathological and genomic methods to identify a BRCA1 or BRCA2 breast cancer profile will gain increasing clinical importance.     

CASP8 polymorphisms, estrogen and progesterone receptor status, and breast cancer risk

OBJECTIVES: This study was conducted to evaluate the potential role of CASP8 genetic polymorphisms in the etiology of breast cancer in a case-control study, Korea. METHODS: Incident breast cancer cases confirmed histologically (n = 1,599) were recruited from two hospitals in Seoul during 2001-2005. Control subjects (n = 1,536) were selected from the Health Examinee Cohort from Seoul and Gyeonggi Province surrounding Seoul, Korea. Three SNPs (D302H D > H, 5'-UTR C > T, and K337K G > A) were genotyped by the primer extension assay. The CASP8 D302H, which was not polymorphic in 48 samples, was excluded in further genotyping. Odds ratios and 95% confidential intervals (95% CIs) were estimated by unconditional logistic regression model adjusted for age at enrollment, education, age at first full-term pregnancy, cigarette smoking, and family history of breast cancer. RESULTS: The 5'-UTR T allele containing genotypes (CT/TT) were associated with an increased risk of breast cancer, compared with those with the CC genotype (OR = 1.13, 95% CI = 0.95-1.34; and OR = 1.48, 95% CI = 1.04-2.10, respectively; P-trend = 0.02). When stratified by the estrogen and progesterone receptor status, the association between the 5'-UTR T allele and breast cancer risk was prominent in ER(+) and PR(+) cases among pre-menopausal women (OR = 1.31, 95% CI = 1.00-1.72 and OR = 1.40, 95% CI = 1.06-1.85, respectively), whereas the association was found prominent in ER(-) or PR(-) cases (OR = 1.32, 95% CI = 0.93-1.87 and OR = 1.42, 95% CI = 1.04-1.94, respectively) among post-menopausal women. CONCLUSION: Our results thus suggest that the CASP8 5'-UTR C > T are associated with breast cancer risks and the effect may be modified by estrogen and progesterone receptor status.     

Association of NAT2, GSTM1, GSTT1, CYP2A6, and CYP2A13 gene polymorphisms with susceptibility and clinicopathologic characteristics of bladder cancer in Central China

Objective: To explore the association of polymorphisms in N-acetyltransferase 2 (NAT2), glutathione S-transferase (GST), cytochrome P450 (CYP) 2A6, and CYP 2A13 genes with susceptibility and clinicopathologic characteristics of bladder cancer in a Chinese population. Methods: In a hospital-based case-control study of 208 cases and 212 controls matched on age and gender, genotypes were determined by PCR-based methods. Risks were evaluated by unconditional logistic regression analysis. Results: It was found that significant associations of the NAT2 slow-acetylator genotype (odds ratio, OR: 2.42; 95% confidence interval, CI: 1.47–3.99), GSTM1 null genotype (OR: 1.64; 95% CI: 1.11–2.42) and GSTM1/GSTT1-double null genotype (OR: 1.72; 95% CI: 1.00–2.95) with increased risk of bladder cancer. Conversely, carriers with at least one CYP2A6*4 allele showed lower risk than the non-carriers (OR: 0.47; 95% CI: 0.28–0.79). The adjusted ORs (95% CI) for smokers with NAT2 slow-acetylator, GSTM1 null, GSTM1/GSTT1-double null genotype, and variant CYP2A6 genotypes were 2.99 (1.44–6.25), 1.98 (1.13–3.48), 2.66 (1.22–5.81) and 0.41 (0.20–0.86), respectively. Furthermore, NAT2 slow-acetylator, GSTM1 null, and GSTM1/GSTT1-double null genotypes were associated with higher tumor grade (P = 0.001, 0.022, and 0.036, respectively), and only NAT2 slow-acetylator genotype was associated with higher tumor stage (P = 0.007). CYP2A13 was not associated with risk or tumor characteristics. Conclusion: It is suggested that NAT2 slow-acetylator, GSTM1 null, GSTM1/GSTT1-double null, and variant CYP2A6 genotypes may play important roles in the development of bladder cancer in Henan area, China.     

The diet,prostate inflammation,and the development of prostate cancer

Evidence that somatic inactivation of GSTP1, encoding the human -class glutathione S-transferase, may initiate prostatic carcinogenesis is reviewed along with epidemiological evidence implicating several environment and lifestyle factors, including the diet and sexually transmitted diseases, as prostate cancer risk factors. An integrated model is presented featuring GSTP1 function as a 'caretaker' gene during the pathogenesis of prostate cancer, in which the early loss of GSTP1 activity renders prostate cells vulnerable to genome damage associated with chronic prostatic inflammation and repeated exposure to carcinogens. The model predicts that the critical prostate carcinogens will be those that are substrates for GSTP1 detoxification and are associated with high prostate cancer risk diet and lifestyle habits.     

Frequent alterations of LOH11CR2A, PIG8 and CHEK1 genes at chromosomal 11q24.1-24.2 region in breast carcinoma: clinical and prognostic implications

To understand the importance of frequent deletions at chromosome 11q24.1-24.2 region in breast carcinoma, alterations (deletion/methylation) of the candidate genes LOH11CR2A, ROBO3, ROBO4, HEPACAM, PIG8 and CHEK1 located in this region were analyzed in 106 breast carcinoma samples. Among these genes, LOH11CR2A showed highest frequency of deletion (56%), followed by PIG8 (35%), CHEK1 (31%) and ROBO3/ROBO4/HEPACAM loci (28%). Comparable frequency of promoter methylation (26–35%) was observed for LOH11CR2A, CHEK1 and PIG8. Overall alterations (deletion/methylation) of these genes were in the following order: LOH11CR2A (60%) > PIG8 (46%) > CHEK1 (41%) and showed significant association with each other. Breast carcinoma samples that were estrogen/progesterone receptor negative showed significantly high deletion and overall alterations than estrogen/progesterone receptor positive samples for LOH11CR2A, CHEK1 and PIG8. The methylation and overall alteration of LOH11CR2A were significantly associated with tumor stages in breast carcinoma. However, in early/late onset and estrogen/progesterone receptor positive/negative breast carcinoma, the overall alterations of LOH11CR2A, PIG8 and CHEK1 were differentially associated with advanced stages, tumor grade and lymph node metastasis. Alterations of PIG8 and CHEK1 were significantly associated with poor prognosis in patients with early age of onset of the disease indicating significant prognostic importance. Quantitative mRNA expression analysis detected reduced expression of the genes in the order LOH11CR2A > CHEK1 > PIG8. Immunohistochemical analysis showed reduced protein expression of PIG8 and CHEK1 that was concordant with their molecular alterations. Thus, our study suggests that LOH11CR2A, PIG8 and CHEK1 are candidate tumor suppressor genes associated with breast carcinoma and have significant clinical as well as prognostic importance.     

Hereditary ovarian cancer in Ashkenazi Jews

Ovarian cancer is the fourth leading cause of cancer deaths among American women. While women in both the Ashkenazi and non-Ashkenazi populations have an estimated 1.7% lifetime risk of acquiring malignancy, the proportion of hereditary ovarian cancer is much higher in the Ashkenazim. Most of this increased proportion of hereditary ovarian cancer risk is accounted for by inherited mutations in the BRCA1 and BRCA2 genes. In the Ashkenazi Jewish population, 29 to 41% of ovarian cancer is believed to be secondary to inheriting one of three founder mutations in BRCA1 and BRCA2, while only 10% of ovarian cancer is attributed to mutations of these genes in non-Ashkenazim. In the US population in general, it is estimated that between 1 out of 345 and 1 out of 1000 individuals carries a BRCA mutation, compared with approximately 1 in 40 individuals of Ashkenazi Jewish descent. The ovarian cancer risk up to age 70 associated with BRCA mutation carriers has been reported to be as high as 66% for BRCA1 and 27% for BRCA2mutation carriers. Ovarian cancer in Ashkenazi kindreds has served as a model for the study of the histopathology of inherited ovarian cancers as well as for the study of risk reduction and screening among all women at inherited risk of ovarian cancer.     

A BRCA1 founder mutation, identified with haplotype analysis, allowing genotype/phenotype determination and predictive testing

We searched for a founder mutation in a population from one geographic region of Norway with prevalent breast/ovarian cancer families. We sampled 33 breast/ovarian cancer families and determined haplotypes of four markers linked to the BRCA1 region. Of the affected 33 index women, 13 (39.4%) shared one haplotype. In five (15% of total), an identical mutation was indicated by an abnormal truncated protein test (PTT) of exon 11 and shown to represent a 1675delA mutation. In the other index women, PTT of exon 11 showed no abnormality. No other BRCA1 founder mutation of this prevalence is likely because no other haplotype was more frequent in affecteds than in controls. All families with the 1675delA mutation in this geographic region may be considered as part of one large kindred. This allows a genotype–phenotype correlation to be precisely determined and used in genetic counselling for predictive testing within this kindred. Identification of identical haplotypes between unrelated affected individuals may be used to estimate the extent of founder effects for any mapped disease, without knowledge of the specific founder mutation.     

Diet, lifestyle and BRCA-related breast cancer risk among French-Canadians

Background Although the connection between diet, lifestyle and hormones suggests that nutritional and lifestyle factors may exert an influence in the etiology of breast cancer (BC), it is not clear whether these factors operate in the same way in women with BRCA1 and BRCA2 (BRCA) gene mutations who already have an elevated BC risk.Methods A case–control study was conducted within a cohort of 80 French-Canadian families with 250 members involving 89 carriers of mutated BRCA gene affected with BC and 48 non-affected carriers. A validated semi-quantitative food frequency questionnaire was used to ascertain dietary intake, and a lifestyle core questionnaire, to gather information on physical activity and other lifestyle risk factors. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in unconditional logistic regression models.Results After adjustment for age, maximum lifetime body mass index (BMI) and physical activity, a positive association was found between total energy intake and BRCA-related BC risk. OR was 2.76 (95%CI: 1.10–7.02; p=0.026 for trend), when comparing the highest tertile of intake with the lowest. The intake of other nutrients and dietary components was not significantly associated with the risk of BC. Age at the time the subjects reached maximum BMI was significantly related to an elevated BC risk (OR=2.90; 95%CI: 1.01–8.36; p=0.046 for trend). In addition, a direct and significant relationship was noted between maximum weight gain since both age 18 and 30 years and BC risk. The ORs were 4.64 (95%CI: 1.52–14.12; p=0.011 for trend) for weight gain since age 18 years and 4.11 (95%CI: 1.46–11.56; p=0.013 for trend) for weight gain since age 30 years, respectively. No overall association was apparent between BRCA-related BC risk and BMI, smoking, and physical activity.Conclusion The results of this preliminary study suggest that weight control in adulthood through dietary energy intake restriction is an important factor for the prevention of BRCA-related BC risk.     

Overexpression of CD24, c-myc and Phospholipase 2A in Prostate Cancer Tissue Samples Obtained by Needle Biopsy

Altered CD24, c-myc and phospholipase 2a expression was reported in different cancers. Our aim was to measure the expression of these genes in prostate cancer tissues, and compare it to non-cancerous samples. Prostate tissue samples were collected by needle biopsy from 20 prostate cancer (PCA) and 11 benign prostate hyperplasic (BPH) patients. RNA was isolated; cDNA synthetized, CD24, c-myc and phospholipase 2A (PL2A) expressions were determined by quantitative real-time PCR method. The expression of β-globin gene was measured for normalization of the gene expression results. Serum prostate specific antigen (PSA) levels were determined by microparticle enzyme immunoassay (MEIA) method. PSA levels were significantly different between the PCA and BPH groups, 252.37 ± 308.33 ng/ml vs. 3.5 ± 2.14 ng/ml (p = 0.001), respectively. CD24 expression was 988.86 ± 3041 ng/μl in prostate tumor and 4.00 ± 4.25 ng/μl in the BPH group (p = 0.035). The c-myc expression was 88.32 ± 11.93 ng/μl in the prostate tumor and 17.08 ± 21.75 ng/μl in the BPH group (p = 0.02), and the PL2A 31.36 ± 67.02 ng/μl was in PCA and 5.56 ± 14.08 ng/μl in BPH (p = 0.025). Gleason’s scores showed correlation with c-myc (p = 0.019) and PSA (p = 0.033) levels. Overexpression of PL2A, CD24 and c-myc was observed in prostate cancer samples using quantitative real-time PCR method.     

Frequent loss of metastatic ability in subclones of Apc,Kras, Tgfbr2, and Trp53 mutant intestinal tumor organoids

Cancer evolution is explained by the accumulation of driver mutations and subsequent positive selection by acquired growth advantages, like Darwin's evolution theory. However, whether the negative selection of cells that have lost malignant properties contributes to cancer progression has not yet been fully investigated. Using intestinal metastatic tumor-derived organoids carrying Apc, Kras, Tgfbr2, and Trp53 quadruple mutations, we demonstrate here that approximately 30% of subclones of the organoids show loss of metastatic ability to the liver while keeping the driver mutations and oncogenic pathways. Notably, highly metastatic subclones also showed a gradual loss of metastatic ability during further passages. Such non-metastatic subclones revealed significantly decreased survival and proliferation ability in Matrigel and collagen gel culture conditions, which may cause elimination from the tumor tissues in vivo. RNA sequencing indicated that stemness-related genes, including Lgr5 and Myb, were significantly downregulated in non-metastatic subclones as well as subclones that lost metastatic ability during additional passages. Furthermore, a CGH analysis showed that non-metastatic subclones were derived from a minor population of parental organoid cells. These results indicate that metastatic ability is continuously lost with decreased stem cell property in certain subpopulations of malignant tumors, and such subpopulations are eliminated by negative selection. Therefore, it is possible that cancer evolution is regulated not only by positive selection but also by negative selection. The mechanism underlying the loss of metastatic ability will be important for the future development of therapeutic strategies against metastasis.     

Flame-broiled food, NAT2acetylator phenotype, and breast cancer risk among women with benign breast disease

Purpose The objective of this study was to examine the association between flame-broiled food consumption, a source of heterocyclic amine exposure, and the development of breast cancer among cohort of women with benign breast disease (BBD). The variation of the association by acetylation phenotype, as determined by the genotypes of selected N-acetyltransferase 2 (NAT2) enzymes, was also examined.Methods Among participants in an ongoing cohort study, 1187 women reported having a breast biopsy for BBD and completed a food frequency questionnaire. NAT2 G857A, NAT2 T341C, and NAT2 G590A genotypes were determined using DNA extracted from blood specimens collected in 1989. Incident cases of breast cancer were identified through linkage of the cohort participants with the Washington County Cancer Registry and the Maryland State Cancer Registry. Follow-up for the BBD cohort began at study entry in 1989 and ended on April 28, 2003.Results Of the women in this study, 77 subsequently developed breast cancer. Results showed that, among rapid acetylators, flame-broiled food intake was associated with a statistically significant increase in the risk of breast cancer (odds ratio (OR) 2.62; 95% confidence interval (CI) 1.06, 6.46). No association was observed between flame-broiled food intake and breast cancer among slow acetylators (OR 0.75; 95% CI 0.39, 1.43).Conclusions These findings suggest that flame-broiled food may be a modifiable risk factor for the progression of BBD to invasive breast cancer among women who have genotypes consistent with rapid acetylation.     

Close correlation between restriction fragment length polymorphism of L-myc gene and susceptibility to gastric cancer

Aim: A common inherited RFLP of the L-myc proto-oncogene has been reported to correlate with cancer susceptibility. Our aim was to test the hypothesis that there was association between L-myc S allele in gastric cancer and predisposition to the disease.Methods: The distribution of L-myc polymorphism in 25 patients with gastric cancer was determined by polymerase chain reaction-based restriction fragment length polymorphism and compared with that of 83 healthy control subjects.Results: We found a significant difference, both in the distribution of the LL, LS and SS genotypes and in the allelic frequencies, between the control group and the patient group; that is, the frequencies of L-myc alleles were, L and S, 0.52 and 0.48, 0.64 and 0.36, respectively. This difference was primarily the result of a high frequency of the S allele among gastric cancer patients compared to controls. There was a significant difference in the distribution of both genotypes (P=0.004) and allele frequencies (P=0.005) between patients with gastric cancer and control groups.Conclusions: Our results suggested that L-myc polymorphism may be significant in an individual’s susceptibility to gastric cancer in Turkey and may be useful for identifying patients at high risk of developing gastric cancer.