Shiro Yokoyama

Fusion of a novel gene, ELKS, to RET due to translocation t(10;12)(q11;p13) in a papillary thyroid carcinoma.

In papillary thyroid carcinomas, the genes for receptor‐type tyrosine kinase, RET or TRKA, are sometimes rearranged, resulting in fusion of its tyrosine kinase domain to 5′ portions of several activating genes. In a papillary thyroid carcinoma, we identified a novel gene (ELKS), the 5′ portion of which is fused to the RET gene by gene rearrangement due to the translocation t(10;12)(q11;p13). Subsequent cloning of the ELKS cDNA revealed that ELKS encodes a novel 948 amino acid peptide and is expressed ubiquitously in human tissues. The presence of multiple coiled‐coil domains in the ELKS product suggests that the ELKS protein forms dimers. Since the tyrosine kinase of RET is activated by dimerization that occurs when its ligands bind to the receptor, fusion of RET with the 5′ dimerization domains of ELKS would activate its cytoplasmic tyrosine kinase constitutively in papillary thyroid carcinomas. Genes Chromosomes Cancer 25:97–103, 1999.

Amplification, up‐regulation and over‐expression of DVL‐1, the human counterpart of the Drosophila disheveled gene, in primary breast cancers

Wnt proteins form a family of highly conserved, secreted signaling molecules that regulate cell‐to‐cell interactions during embryogenesis. Wnt genes and Wnt signaling are also implicated in cancer. It has been shown that Wnt proteins bind to receptors of the frizzled family on the cell surface. Through several cytoplasmic relay components including DVL‐1, the human counterpart of the Drosophila disheveled gene, the signal is transduced to β‐catenin, which then enters the nucleus and forms a complex with T‐cell factor (TCP) to activate transcription of Wnt target genes. We describe here the amplification of DVL‐1 in 13 of 24 primary breast cancers examined, and increased expression of this gene in 11 of those tumors in comparison to corresponding non‐cancerous breast tissues. Immunohistochemical staining demonstrated that DVL‐1 protein was prominent in the cytoplasm of cancer cells, but not in normal epithelial cells of the mammary duct or in myoepithelial cells. These data indicate that amplification and increased expression of the DVL‐1 gene may play some role in human breast carcinogenesis through derangement of the Wnt signaling pathway.

Dietary intake of folate, vitamin B2, vitamin B6, vitamin B12, genetic polymorphism of related enzymes, and risk of breast cancer: a case-control study in Japan.

We investigated associations among intake of folate, vitamin B2, vitamin B6, vitamin B12, and polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MTR) genes and breast cancer risk in a Japanese population. A hospital based, case-control study was conducted in Nagano Prefecture, Japan, in 388 pairs of patients with histologically confirmed invasive breast cancer and age- and area-matched controls selected from medical checkup examinees. Energy-adjusted intakes of folate and other B vitamins were derived from a validated food frequency questionnaire. Genotyping was completed for MTHFR (C677T and A1298T) and MTR (A2756G). Odds ratios and 95% confidence intervals were calculated by the conditional logistical regression model. Median dietary folate intake (μg/day) in the control group was 438.2 (interquartile range: 354.9–542.9). Neither dietary intake of folate, vitamin B2, vitamin B6, or vitamin B12 nor polymorphisms of MTHFR or MTR genes were significantly associated with breast cancer risk. Further, no significant interaction was found among nutrients, polymorphisms, and breast cancer risk. Associations of nutrients with breast cancer risk did not differ by hormone receptors status. We conclude that dietary intake of folate and related B vitamins and genotypes of MTHFR or MTR have no overall association with breast cancer risk in Japanese women.

Cross-sectional analysis of germline BRCA1 and BRCA2 mutations in Japanese patients suspected to have hereditary breast/ovarian cancer.

The prevalence of BRCA1/2 germline mutations in Japanese patients suspected to have hereditary breast/ovarian cancer was examined by a multi‐institutional study, aiming at the clinical application of total sequencing analysis and validation of assay sensitivity in Japanese people using a cross‐sectional approach based on genetic factors estimated from personal and family histories. One hundred and thirty‐five subjects were referred to the genetic counseling clinics and enrolled in the study. Full sequencing analysis of the BRCA1/2 gene showed 28 types of deleterious mutations in 36 subjects (26.7%), including 13 types of BRCA1 mutations in 17 subjects (12.6%) and 15 types of BRCA2 mutations in 19 subjects (14.1%). Subjects were classified into five groups and 22 subgroups according to their personal and family history of breast and/or ovarian cancer, and the prevalence of deleterious mutations was compared with previously reported data in non‐Ashkenazi individuals. Statistical analysis using the Mantel‐Haenszel test for groups I through IV revealed that the prevalence of Japanese subjects was significantly higher than that of non‐Ashkenazi individuals (P = 0.005, odds ratio 1.87, 95% confidence interval 1.22–2.88). Family history of the probands suffering from breast cancer indicated risk factors for the presence of deleterious mutations of BRCA1/2 as follows: (1) families with breast cancer before age 40 within second degree relatives (P = 0.0265, odds ratio 2.833, 95% confidence interval 1.165–7.136) and (2) families with bilateral breast cancer and/or ovarian cancer within second degree relatives (P = 0.0151, odds ratio 2.88, 95% confidence interval 1.25–6.64). (Cancer Sci 2008; 99: 1967–1976)

Dietary cadmium intake and breast cancer risk in Japanese women: a case-control study.

Cadmium, an environmental pollutant, may act like an estrogen and be a potential risk factor for estrogen-dependent diseases such as breast cancer. We examined the hypothesis that higher dietary cadmium intake is associated with risk of overall and hormone receptor-defined breast cancer in Japanese women, a population with a relatively high cadmium intake. The study was conducted under a case-control design in 405 eligible matched pairs from May 2001 to September 2005 at four hospitals in Nagano Prefecture, Japan. Dietary cadmium intake was estimated using a food frequency questionnaire. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer and its hormone-receptor-defined subtypes were calculated by tertile of dietary cadmium intake. We found no significant association between dietary cadmium and risk of total breast cancer in either crude or multivariable-adjusted analysis. Adjusted ORs for tertiles of cadmium intake were 1.00, 1.19, and 1.23 (95% CI, 0.76-2.00; P for trend=0.39) for whole breast cancer. Further, no significant associations were seen across strata of menopausal status, smoking, and diabetes in multivariable-adjusted models except for adjusted OR for continuous cadmium intake in postmenopausal women. A statistically significant association was found for estrogen receptor-positive (ER+) tumors among postmenopausal women (adjusted OR=1.00, 1.16, and 1.94 [95% CI, 1.04-3.63; P for trend=0.032]). Although the present study found no overall association between dietary cadmium intake and breast cancer risk, higher cadmium intake was associated with increased risk of ER+ breast cancer in postmenopausal women, at least at regular intake levels in Japanese women in the general population. Further studies are needed to confirm this association.

Serum organochlorines and breast cancer risk in Japanese women: a case-control study.

ObjectiveMost epidemiological studies of the association between breast cancer risk and exposure to organochlorine pesticides or polychlorinated biphenyls (PCBs), which are suspected endocrine disrupters and potential risk factors for human breast cancer, have been conducted in western countries, and the majority of results have been null and the rest inconsistent. Here, we examined these associations in Japanese women in the largest study in Asian women to date.MethodsThe study was a matched case–control study of breast cancer with 403 eligible matched pairs from May 2001 to September 2005 at four hospitals in Nagano Prefecture, Japan.MeasurementsSerum samples were measured for PCBs and nine pesticide-related organochlorines, including dichlorodiphenyltrichloroethane (DDT). Odds ratios of breast cancer or its hormone-receptor-defined subtypes according to serum organochlorines were calculated.ResultsNo increase in the risk of breast cancer was seen among women with higher serum concentrations of any organochlorine: o,p′-DDT, p,p′-DDT, p,p′-dichlorodiphenyldichloroethylene, hexachlorobenzene, β-hexachlorocyclohexane, trans-nonachlor, cis-nonachlor, oxychlordane, mirex, or PCBs. Rather, higher serum levels of cis-nonachlor, mirex, or total PCBs were associated with a decreased risk of breast cancerConclusionsOverall, these results suggest that breast cancer risk in Japan, a low-incidence country, is similar to that in western countries in terms of organochlorine exposure.

The rate of tumour growth does not distinguish between malignant and benign thyroid nodules

OBJECTIVE To clarify whether or not the rate of tumour growth is a useful measure for distinguishing papillary thyroid cancer from benign nodules. DESIGN Retrospective study. SETTING Teaching hospital, Japan. SUBJECTS Fourteen patients with 27 nodules (<20 mm) followed up for 20 months or more. INTERVENTIONS High resolution ultrasonography (US). MAIN OUTCOME MEASURE Growth rate. RESULTS There were 15 papillary thyroid cancers and 12 benign nodules. The median tumour diameters at the first and the last US examination were 9.0 mm (range 6-19) and 9.0 mm (range 5-21) in papillary thyroid cancers followed up for 37 months (range 21-85), and 11.5 mm (range 4-19) and 11.5 mm (range 5-23) in benign nodules followed up for 38 months (range 20-84), respectively. CONCLUSION The rate of growth of thyroid nodules as documented by ultrasound did not prove to be useful in distinguishing between malignancy and benign disease of small thyroid nodules (<20 mm).

Isoflavone, polymorphisms in estrogen receptor genes and breast cancer risk in case-control studies in Japanese, Japanese Brazilians and non-Japanese Brazilians

Epidemiologic studies have shown an inverse association between isoflavones and breast cancer risk. Because isoflavones bind estrogen receptors, we hypothesized that polymorphisms in the estrogen receptor genes might modify the association between isoflavone intake and breast cancer risk. We conducted hospital‐based case‐control studies of patients aged 20–74 years with primary, incident, histologically confirmed invasive breast cancer, and matched controls from among medical checkup examinees in Nagano, Japan, and from cancer‐free patients in São Paulo, Brazil. A total of 846 pairs (388 Japanese, 79 Japanese Brazilians and 379 non‐Japanese Brazilians) completed validated food frequency questionnaires, and provided blood samples. Five single nucleotide polymorphisms in the estrogen receptor alpha (rs9340799, rs1913474, and rs2234693) and beta (rs4986938 and rs1256049) genes were genotyped. We found no consistent association between the five single nucleotide polymorphisms and breast cancer risk among the three populations. In analyses of combinations of isoflavone intake and single nucleotide polymorphisms, an inverse association between intake and risk was limited to women with the GG genotype of the rs4986938 polymorphism for postmenopausal Japanese (odds ratio for highest versus lowest tertile = 0.47; P for trend = 0.01), Japanese Brazilians (odds ratio for highest versus lowest median = 0.31) and non‐Japanese Brazilians (odds ratio for consumers versus non‐consumers = 0.37) (P for interaction = 0.11, 0.08, and 0.21, respectively). We found no remarkable difference for the other four polymorphisms. Our findings suggest that polymorphisms in the estrogen receptor beta gene may modify the association between isoflavone intake and breast cancer risk. (Cancer Sci 2009; 100: 927–933)

Genetic polymorphisms in estrogen metabolism and breast cancer risk in case-control studies in Japanese, Japanese Brazilians and non-Japanese Brazilians

Although many studies have examined associations between single nucleotide polymorphisms (SNPs) in the CYP1A1, CYP1A2 and CYP1B1 genes and breast cancer risk, no study has examined functional SNPs in the CYP3A5 gene and only a small number of studies have been investigated in Japanese populations. To examine the association between six SNPs, CYP1A1*2A, CYP1A1*2C, CYP1A2*1F, CYP1B1 Arg48Gly, CYP1B1 Leu432Val and CYP3A5*3 and breast cancer risk, therefore, we conducted hospital-based case–control studies in Nagano, Japan and São Paulo, Brazil including 873 pairs (403 Japanese (JJ), 81 Japanese Brazilians (JB) and 389 non-Japanese Brazilians (NJB)). Although we found no significant association in the three populations combined, subgroup analyses revealed statistically significant associations of CYP1A2*1F in NJB, and CYP1B1 Leu432Val and CYP3A5*3 in JJ with breast cancer risk. Compared to women with the AA genotype in CYP1A2*1F, the odds ratio (OR) (95% confidence interval (CI)) for NJB with the CC genotype was 0.54 (0.32–0.90); that for JJ with Leu/Val+Val/Val versus Leu/Leu genotype in CYP1B1 Leu432Val was 0.68 (0.48–0.97); and that for JJ with *3/*1+*1/*1 versus *3/*3 genotype in CYP3A5*3 was 1.49 (1.10–2.04). Our findings provide further evidence that genetic polymorphisms related to estrogen metabolism may play a role in the development of breast cancer.

Ret/PTC3 is the most frequent form of gene rearrangement in papillary thyroid carcinomas in Japan.

AbstractRearrangements of the RET and TRK proto-oncogenes, which generate fusion oncogenes, are frequent in papillary thyroid carcinomas in Caucasian populations. To determine the spectrum of gene rearrangements in Japanese patients, we systematically examined 40 papillary thyroid carcinomas for all possible types of gene fusion events involving RET or TRK genes. RET rearrangements were found in ten tumors (25%): ret/PTC1 had occurred in two tumors, ret/PTC2 in one, ret/PTC3 in six, and a novel RET rearrangement in the remaining patient. In this last patient, the 5′ novel sequence was fused in-frame to the RET amino acid sequence; thus, the fusion gene may encode a protein with a RET kinase domain at the carboxy terminus. The RET gene was fused to 5′ donor sequences at the beginning of exon 12 in all ten tumors. No rearrangements involving the TRK gene were found in this panel of carcinomas. Our results indicated that constitutive activation of the RET by gene rearrangement is a frequent mechanism of papillary thyroid carcinogenesis in Japanese adults.