Asuka Murata

Kumamoto University, Kumamoto-shi, Kumamoto Prefecture, Japan

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Publications (10)38.01 Total impact

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    ABSTRACT: We evaluated the need for primary tumor resection in patients with colorectal cancer (CRC) and synchronous unresectable metastases who underwent chemotherapy, and identified the associations between the primary tumor characteristics and risk of intestinal obstruction or perforation. We retrospectively analyzed the survival and complication rates of patients with synchronous metastatic CRC treated between April 2005 and December 2011. Of 131 patients, 68 underwent primary tumor resection before chemotherapy, and 63 were treated without resection before chemotherapy. The overall survival (OS) did not significantly differ between the two groups (log-rank P = 0.53). In the resection group, 12 patients (17.6 %) developed postoperative complications. In the non-resection group, 16 patients (25.4 %) required surgical intervention owing to obstruction or perforation during their treatment. Surgical intervention did not affect the OS. A circumferential tumor was a risk factor for obstruction or perforation of the colorectum in non-resected patients (odds ratio = 11.163; P = 0.006). Resection of primary tumors before chemotherapy is unnecessary in selected patients with synchronous metastatic colorectal cancer. A circumferential tumor is a risk factor for obstruction or perforation during chemotherapy in cases without primary tumor resection.
    Surgery Today 03/2014; · 0.96 Impact Factor
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    ABSTRACT: Global DNA hypomethylation plays a crucial role in genomic instability and carcinogenesis. DNA methylation of the long interspersed nucleotide element-1, L1 (LINE-1) repetitive element is a good indicator of the global DNA methylation level, and is attracting interest as a useful marker for predicting cancer prognosis. Our previous study using more than 200 esophageal squamous cell carcinoma (ESCC) specimens demonstrated the significant relationship between LINE-1 hypomethylation and poor prognosis. However, the mechanism by which LINE-1 hypomethylation affects aggressive tumor behavior has yet to be revealed. To examine the relationship between LINE-1 hypomethylation and DNA copy number variations, we investigated LINE-1 hypomethylated and LINE-1 hypermethylated ESCC tumors by comparative genomic hybridization array. LINE-1 hypomethylated tumors showed highly-frequent genomic gains at various loci containing candidate oncogenes such as CDK6. LINE-1 methylation levels were significantly associated with CDK6 mRNA and CDK6 protein expression levels in ESCC specimens. In our cohort of 129 ESCC patients, cases with CDK6-positive expression experienced worse clinical outcome compared with those with CDK6-negative expression, supporting the oncogenic role of CDK6 in ESCC. In addition, we found that the prognostic impact of LINE-1 hypomethylation might be attenuated by CDK6 expression. LINE-1 hypomethylation (i.e., global DNA hypomethylation) in ESCC might contribute to the acquisition of aggressive tumor behavior through genomic gains of oncogenes such as CDK6.
    Clinical Cancer Research 01/2014; · 7.84 Impact Factor
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    ABSTRACT: Insulin like growth factor 2 gene (IGF2) is normally imprinted. Loss of imprinting (LOI) of IGF2 in humans is associated with an increased risk of cancer and is controlled by CpG-rich regions known as differentially methylated regions (DMRs). Specifically, the methylation level at IGF2 DMR0 is correlated with IGF2 LOI and is a suggested surrogate marker for IGF2 LOI. A relationship between IGF2 DMR0 hypomethylation and poor prognosis has been shown in colorectal cancer. However, to our knowledge, no study has examined the relationships among the IGF2 DMR0 methylation level, LOI, and clinical outcome in esophageal squamous cell carcinoma (ESCC). The IGF2 imprinting status was screened using ApaI polymorphism, and IGF2 protein expression was evaluated by immunohistochemistry with 30 ESCC tissue specimens. For survival analysis, IGF2 DMR0 methylation was measured using a bisulfite pyrosequencing assay with 216 ESCC tissue specimens. Twelve (40 %) of 30 cases were informative (i.e., heterozygous for ApaI), and 5 (42 %) of 12 informative cases displayed IGF2 LOI. IGF2 LOI cases exhibited lower DMR0 methylation levels (mean 23 %) than IGF2 non-LOI cases (37 %). The IGF2 DMR0 methylation level was significantly associated with IGF2 protein expression. Among 202 patients eligible for survival analysis, IGF2 DMR0 hypomethylation was significantly associated with higher cancer-specific mortality. The IGF2 DMR0 methylation level in ESCC was associated with IGF2 LOI and IGF2 protein expression. In addition, IGF2 DMR0 hypomethylation was associated with a shorter survival time, suggesting its potential role as a prognostic biomarker.
    Annals of Surgical Oncology 12/2013; · 4.12 Impact Factor
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    ABSTRACT: It is generally accepted that overexpression of p53 protein is associated with poor prognosis in gastric, lung, and other types of cancer. However, the prognostic significance of p53 aberrations in esophageal cancer remains unclear. This is the largest study (n = 266) examining clinical and prognostic features of p53 immunohistochemical expression in esophageal squamous cell carcinoma. In 139 (52 %) esophageal tumors, nuclear immunoreactivity for p53 protein was detected. p53 aberrant expression was not associated with sex, age, preoperative treatment, TNM stage, or histological grade. Furthermore, p53 expression did not correlate with disease-free survival (P = 0.73) or overall survival (P = 0.62). In addition, no significant modification effect by any of the covariates in the survival analysis was observed (all P > 0.15). In conclusion, our large-scale study demonstrates that p53 expression has no impact on the prognosis of esophageal squamous cell carcinoma.
    Medical Oncology 12/2013; 30(4):728. · 2.14 Impact Factor
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    ABSTRACT: Epigenetic alterations, such as DNA methylation, histone modification and the loss of genome imprinting, are important indicators of human carcinogenesis. DNA methylation is a fundamental epigenetic process that modulates the gene expression levels. In cancer cells, DNA methylation may be altered in two principle ways: global DNA hypomethylation and site-specific CpG island promoter hypermethylation. Long interspersed element-1 (LINE-1 or L1) is a repetitive DNA retrotransposon that duplicates via a copy-and-paste genetic mechanism. Since LINE-1 constitutes a substantial portion (approximately 17 %) of the human genome, the extent of LINE-1 methylation is regarded to be a surrogate marker of global DNA methylation. Measuring the level of LINE-1 methylation using pyrosequencing technology has emerged as a cost-effective and high-throughput method for assessing the global DNA methylation status. In some types of gastrointestinal (GI) cancers, LINE-1 hypomethylation is strongly associated with a poor prognosis, supporting its potential role as a prognostic marker. In addition, the LINE-1 methylation level may prove to be a useful clinical biomarker for assessing the risk of cancer or predicting the chemotherapeutic efficacy of treatment in patients with GI cancers. In this article, we summarize current knowledge regarding LINE-1 methylation and its clinical implications in GI cancers, including colorectal cancer, gastric cancer and esophageal cancer.
    Surgery Today 10/2013; · 0.96 Impact Factor
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    ABSTRACT: Background:LINE-1 methylation level is a surrogate marker of global DNA methylation. LINE-1 methylation in primary colorectal cancers (CRCs) is highly variable and strongly associated with a poor prognosis. However, no study has examined LINE-1 methylation levels of metastatic CRCs in relation to prognosis or assessed the heterogeneity of LINE-1 methylation level within the primary CRCs.Methods:Pyrosequencing was used to quantify LINE-1 methylation level in 42 liver metastases, 26 matched primary tumours, and 6 matched lymph node (LN) metastases. KRAS, BRAF, and PIK3CA mutation status and microsatellite instability (MSI) status were also examined.Results:The distribution of LINE-1 methylation level in liver metastases was as follows: mean, 67.3; range, 37.1-90.1. Primary tumours showed LINE-1 methylation levels similar to those of matched liver and LN metastases. The difference in LINE-1 methylation level between superficial areas and invasive front areas was within 7.0 in all six cases evaluated. Prognostic impact of LINE-1 hypomethylation in liver metastases on overall survival was not observed. The concordance rate was 94% for KRAS, 100% for BRAF, 88% for PIK3CA, and 97% for MSI.Conclusion:Alteration of LINE-1 methylation level may occur in early CRC tumorigenesis, and the LINE-1 methylation level is relatively stable during CRC progression.British Journal of Cancer advance online publication, 13 June 2013; doi:10.1038/bjc.2013.289 www.bjcancer.com.
    British Journal of Cancer 06/2013; · 5.08 Impact Factor
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    ABSTRACT: PURPOSE: PIK3CA encodes the catalytic subunit of PI3K, p110α. Mutant PIK3CA stimulates the AKT pathway and promotes cancer cell proliferation. PIK3CA mutations have been associated with poor prognosis in patients with colorectal or lung cancer. In contrast, the relationship between PIK3CA mutations and favorable prognoses has been shown in breast cancer. However, the influence of PIK3CA mutations on the prognosis of esophageal squamous cell carcinoma (ESCC) patients remains unclear. EXPERIMENTAL DESIGN: Using a non-biased database of 219 curatively resected ESCCs and eight esophageal cancer cell lines, we evaluated PIK3CA mutational status by pyrosequencing. The expression of p53 and phosphorylated AKT (i.e., AKT activation) was evaluated by immunohistochemistry. RESULTS: PIK3CA mutations in exon 9 and/or 20 were detected in 46 cases (21%). No ESCC cell line harbored PIK3CA mutations. PIK3CA mutations were significantly associated with phosphorylated AKT expression, but not with p53 expression, sex, age at surgery, tobacco use, alcohol use, or histological grade. Compared with wild-type PIK3CA cases, patients with PIK3CA mutations in exons 9 and/or 20 experienced significantly better disease-free survival [log-rank P=0.0089; univariate HR= 0.37, 95% confidence interval (CI) 0.15-0.75, P=0.0042; multivariate HR=0.34, 95% CI 0.10-0.86, P=0.021] and overall survival (log-rank P=0.012; univariate HR=0.38, 95% CI 0.16-0.78, P=0.0060; multivariate HR=0.35, 95% CI 0.10-0.90, P=0.028]. CONCLUSIONS: PIK3CA mutations in ESCC are associated with longer survival, suggesting its role as a prognostic biomarker. Future studies are needed to confirm this association and to elucidate the exact mechanisms by which PIK3CA mutations affect tumor behavior.
    Clinical Cancer Research 03/2013; · 7.84 Impact Factor
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    ABSTRACT: BACKGROUND: Epidermal growth factor receptor (EGFR) signaling is one of the most promising targets for molecular-targeted therapies in esophageal squamous cell carcinoma (ESCC). Thus, the molecular diagnosis of KRAS and BRAF mutations is clinically important in therapeutic decision making. However, the frequency of KRAS and BRAF mutations in ESCCs remains inconclusive because of the limited sample sizes of previous studies (all N ≤ 80). Pyrosequencing is a nonelectrophoretic nucleotide extension sequencing technology that can be used for mutation testing. METHODS: The frequency of KRAS and BRAF mutations was examined using a nonbiased database of 203 resected ESCCs and a high-throughput pyrosequencing assay. RESULTS: The validity of the KRAS pyrosequencing method was initially demonstrated by detection of all 4 types of KRAS mutations [c.35G>T (codon 12 GGT>GTT), c.35G>A (codon 12 GGT>GAT), c.34G>T (codon 12 GGT>TGT), c.38G>A mutation (codon 13 GGC>GAC)], which had been previously diagnosed using Scorpion-ARMS technology, in 9 colon cancer tissues (9 of 9; 100 %). Similar results were demonstrated for BRAF mutational status in 3 colon cancer cell lines (HCT116, Colo201, and HT29), which were validated by Sanger dideoxy sequencing. Subsequently, the KRAS mutation was found to be extremely rare (1 of 203; 0.5 %), and the BRAF mutation was absent (0 of 203; 0 %), in the dataset of 203 ESCCs. CONCLUSIONS: These results suggest that KRAS and BRAF mutations play a limited role in the development of ESCC and that mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in ESCC.
    Annals of Surgical Oncology 12/2012; · 4.12 Impact Factor
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    ABSTRACT: BACKGROUND: Genome-wide DNA hypomethylation plays an important role in genomic instability and carcinogenesis. DNA methylation in the long interspersed nucleotide element-1, L1 (LINE-1) repetitive element is a good indicator of the global DNA methylation level. In some types of human neoplasms, LINE-1 methylation level is attracting interest as a predictive marker for patient prognosis. However, the prognostic significance of LINE-1 hypomethylation in gastric cancer remains unclear. METHODS: Using 203 resected gastric cancer specimens, we quantified LINE-1 methylation using bisulfite-pyrosequencing technology. A Cox proportional hazards model was used to calculate the hazard ratio (HR), adjusted for the clinical and pathological variables. RESULTS: Gastric cancers showed significantly lower LINE-1 methylation levels compared to matched normal gastric mucosa (p < 0.0001; n = 74). Tumoral LINE-1 methylation range was 11.6-97.5 on a 0-100 scale (n = 203; mean 71.4, median 74.4, standard deviation 12.9). LINE-1 hypomethylation was significantly associated with shorter overall survival [log-rank p = 0.029; univariate HR 2.01, 95 % confidence interval (CI) 1.09-3.99, p = 0.023; stage-matched HR 1.88, 95 % CI 1.02-3.74, p = 0.041; multivariate HR 1.98, 95 % CI 1.04-4.04, p = 0.036]. No significant effect modification was observed by any of the covariates in survival analysis (all p interaction >0.25). CONCLUSIONS: LINE-1 hypomethylation in gastric cancer is associated with shorter survival, suggesting that it has potential for use as a prognostic biomarker.
    Gastric Cancer 11/2012; · 3.99 Impact Factor
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    ABSTRACT: A 49-year-old woman was admitted to our hospital under suspicion of an enlarging hepatic tumor, which had been previously diagnosed to be a cavernous hemangioma. Computed tomography revealed three enhanced tumors, one measuring 15 cm in diameter within the right lobe of the liver and two intrahepatic metastases in Couinaud's hepatic segments 3 and 5. We diagnosed the patient to have primary liver cancer, and suspected a combined liver tumor preoperatively. We performed a right trisectionectomy with radiofrequency ablation of the intrahepatic metastasis in S3. According to the immunohistochemical findings of the resected specimen and the findings of postoperative imaging studies, the tumor was diagnosed to be a primary neuroendocrine tumor in the liver. The patient is presently alive without recurrence at 33 months after the operation.
    Surgery Today 12/2011; 41(12):1655-60. · 0.96 Impact Factor