Nobukazu Fujimoto

Epigenetic Profiles Distinguish Malignant Pleural Mesothelioma from Lung Adenocarcinoma

Malignant pleural mesothelioma (MPM) is a fatal thoracic malignancy, the epigenetics of which are poorly defined. We performed high-throughput methylation analysis covering 6,157 CpG islands in 20 MPMs and 20 lung adenocarcinomas. Newly identified genes were further analyzed in 50 MPMs and 56 adenocarcinomas via quantitative methylation-specific PCR. Targets of histone H3 lysine 27 trimethylation (H3K27me3) and genetic alterations were also assessed in MPM cells by chromatin immunoprecipitation arrays and comparative genomic hybridization arrays. An average of 387 genes (6.3%) and 544 genes (8.8%) were hypermethylated in MPM and adenocarcinoma, respectively. Hierarchical cluster analysis showed that the two malignancies have characteristic DNA methylation patterns, likely a result of different pathologic processes. In MPM, a separate subset of genes was silenced by H3K27me3 and could be reactivated by treatment with a histone deacetylase inhibitor alone. Integrated analysis of these epigenetic and genetic alterations revealed that only 11% of heterozygously deleted genes were affected by DNA methylation and/or H3K27me3 in MPMs. Among the DNA hypermethylated genes, three (TMEM30B, KAZALD1, and MAPK13) were specifically methylated only in MPM and could serve as potential diagnostic markers. Interestingly, a subset of MPM cases (4 cases, 20%) had very low levels of DNA methylation and substantially longer survival, suggesting that the epigenetic alterations are one mechanism affecting progression of this disease. Our findings show a characteristic epigenetic profile of MPM and uncover multiple distinct epigenetic abnormalities that lead to the silencing of tumor suppressor genes in MPM and could serve as diagnostic or prognostic targets.

Cancer prevention with green tea and monitoring by a new biomarker, hnRNP B1

The study of green tea polyphenols as a cancer preventative is approaching a new era, with significant results accumulating rapidly. This paper briefly reviews four topics related to mechanisms of action of tea polyphenols: (I) identification of the genes commonly affected by EGCG, as demonstrated by Clontechs Atlas cDNA Expression Array; (II) the significance of heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1) as a new biomarker for early detection of lung cancer, and inhibition of its expression by EGCG; (III) the synergistic or additive effects of EGCG with the cancer preventive agents, sulindac and tamoxifen, on induction of apoptosis in PC-9 cells and on inhibition of intestinal tumor development in multiple intestinal neoplasia (Min) mice; (IV) the results of a 10 year prospective cohort study demonstrating the effectiveness of daily consumption of green tea in preventing cancer, and a prototype study for developing green tea beverage as cancer preventive.

Risk factors for development of radiation pneumonitis following radiation therapy with or without chemotherapy for lung cancer

PURPOSE To determine the risk factors contributing to development of radiation pneumonitis (RP) in patients with lung cancer who undergo radiation therapy to the thorax. METHODS AND MATERIALS Development and severity of RP were retrospectively analyzed for 89 patients with lung cancer who underwent radiation therapy with or without chemotherapy at the National Shikoku Cancer Center Hospital between 1991 and 1995. The severity of RP was determined using a modified grading scale based on that of the Radiation Therapy Oncology Group and the European Organization for the Research and Treatment of Cancer. RESULTS Fifty-two (58%) patients developed RP: 34 patients with Grade 1, 5 with Grade 2, 8 with Grade 3, and 5 with Grade 5 RP. Severe RP tended to develop earlier than less severe RP, but not to a significant extent (p = 0.151). On logistic regression analysis including both patient condition and treatment factors, development of Grade 1 or more severe RP was most frequently observed for Stage I-II disease (p = 0.011). The use of chemotherapy, large daily radiation dose, and once-daily fractionation (vs. twice-daily fractionation) were possibly related to the development of RP (p = 0.057, p = 0.069, and p = 0.092, respectively). For the group of 48 patients who underwent chemoradiation therapy, the use of large daily radiation dose was a significant risk factor for RP (p = 0.014). In addition, the use of once-daily fractionation was a marginally significant risk factor (p = 0.052). Among chemotherapy drugs administered, cisplatin was a favorable factor (p = 0.011), while adriamycin was a risk factor (p = 0.061). CONCLUSIONS In radiation therapy for lung cancer, administration of a large daily dose should be avoided in order to prevent RP, particularly when radiation therapy is combined with chemotherapy.

National survey of malignant mesothelioma and asbestos exposure in Japan

In the present study, malignant mesothelioma (MM) cases in Japan were investigated retrospectively. We extracted records for 6030 cases of death due to MM between 2003 and 2008 to clarify the clinical features of MM, including its association with asbestos exposure (AE). Of all these cases, a clinical diagnosis of MM was confirmed for 929. The origin of MM included the pleura in 794 cases (85.5%), the peritoneum in 123 cases (13.2%), the pericardium in seven cases (0.8%), and the testicular tunica vaginalis in five cases (0.5%). The histological subtypes of MM included 396 epithelioid (55.9%), 154 sarcomatoid (21.7%), 126 biphasic (17.8%), and 33 cases (4.7%) classified as “other types”. Of all the MM cases, AE was indicated in 76.8% and pleural plaques were detected in 34.2%. The number of asbestos particles was determined in 103 cases of MM. More than 1000 asbestos particles per gram dried lung tissue were detected in 74.8% of cases and more than 5000 particles were detected in 43.7% of cases. We compared patient characteristics and the diagnostic procedures for MM before and after the “Kubota shock”. Compared with the early phase of this study (2003–2005), the median age at diagnosis of MM was higher, the number of cases without definite diagnosis of MM was lower, the proportion of cases diagnosed by thoracoscopy was higher, and the percentage of cases in which the occupational history was described in the medical records was significantly higher in the later phase (2006–2008). Our study confirmed that more than 70% of MM cases in Japan are associated with AE. The “Kubota shock” may affect some features pertaining to MM. (Cancer Sci 2012; 103: 483–490)

Identification of cancer stem cell markers in human malignant mesothelioma cells

Malignant mesothelioma (MM) is an aggressive and therapy-resistant neoplasm arising from the pleural mesothelial cells and usually associated with long-term asbestos exposure. Recent studies suggest that tumors contain cancer stem cells (CSCs) and their stem cell characteristics are thought to confer therapy-resistance. However, whether MM cell has any stem cell characteristics is not known. To understand the molecular basis of MM, we first performed serial transplantation of surgical samples into NOD/SCID mice and established new cell lines. Next, we performed marker analysis of the MM cell lines and found that many of them contain SP cells and expressed several putative CSC markers such as CD9, CD24, and CD26. Interestingly, expression of CD26 closely correlated with that of CD24 in some cases. Sorting and culture assay revealed that SP and CD24(+) cells proliferated by asymmetric cell division-like manner. In addition, CD9(+) and CD24(+) cells have higher potential to generate spheroid colony than negative cells in the stem cell medium. Moreover, these marker-positive cells have clear tendency to generate larger tumors in mouse transplantation assay. Taken together, our data suggest that SP, CD9, CD24, and CD26 are CSC markers of MM and could be used as novel therapeutic targets.

Integrated analysis of genetic and epigenetic alterations reveals CpG island methylator phenotype associated with distinct clinical characters of lung adenocarcinoma

DNA methylation affects the aggressiveness of human malignancies. Cancers with CpG island methylator phenotype (CIMP), a distinct group with extensive DNA methylation, show characteristic features in several types of tumors. In this study, we initially defined the existence of CIMP in 41 lung adenocarcinomas (AdCas) through genome-wide DNA methylation microarray analysis. DNA methylation status of six CIMP markers newly identified by microarray analysis was further estimated in a total of 128 AdCas by bisulfite pyrosequencing analysis, which revealed that 10 (7.8%), 40 (31.3%) and 78 (60.9%) cases were classified as CIMP-high (CIMP-H), CIMP-low and CIMP-negative (CIMP-N), respectively. Notably, CIMP-H AdCas were strongly associated with wild-type epidermal growth factor receptor (EGFR), males and heavy smokers (P = 0.0089, P = 0.0047 and P = 0.0036, respectively). In addition, CIMP-H was significantly associated with worse prognosis; especially among male smokers, CIMP-H was an independent prognostic factor (hazard ratio 1.7617, 95% confidence interval 1.0030-2.9550, P = 0.0489). Compellingly, the existence of CIMP in AdCas was supported by the available public datasets, such as data from the Cancer Genome Atlas. Intriguingly, analysis of AdCa cell lines revealed that CIMP-positive AdCa cell lines were more sensitive to a DNA methylation inhibitor than CIMP-N ones regardless of EGFR mutation status. Our data demonstrate that CIMP in AdCas appears to be a unique subgroup that has distinct clinical traits from other AdCas. CIMP classification using our six-marker panel has implications for personalized medical strategies for lung cancer patients; in particular, DNA methylation inhibitor might be of therapeutic benefit to patients with CIMP-positive tumors.

Serum hepatocyte growth factor/scatter factor levels in small cell lung cancer patients

Serum hepatocyte growth factor/scatter factor (HGF/SF) levels were measured in 25 patients with small cell lung cancer (SCLC), 16 patients with benign lung diseases and 15 healthy subjects with an enzyme-linked immunosorbent assay. The patients with SCLC did not have bacterial or interstitial pneumonia. Patients with benign lung diseases included eight with bacterial pneumonia, three with interstitial pneumonia, and five with benign lung tumor. Serum HGF/SF levels were significantly higher in patients with SCLC (mean +/- S.D.: 0.40 +/- 0.17 ng/ml) than in healthy subjects (0.26 +/- 0.093 ng/ml) (P = 0.0083). Patients with bacterial pneumonia had significantly higher serum HGF/SF (0.52 +/- 0.19 ng/ml) than did those with benign lung tumors (0.27 +/- 0.058 ng/ml) and healthy subjects (P = 0.013 and P = 0.0019, respectively). By clinical stage of SCLC, HGF/SF levels were 0.34 +/- 0.12 and 0.47 +/- 0.20 ng/ml in patients with limited disease and extensive disease, respectively; this difference was not significant (P = 0.080). Although serum HGF/SF levels were increased in patients with SCLC, this increase might not have been related to tumor burden.

Frequent p16 inactivation by homozygous deletion or methylation is associated with a poor prognosis in Japanese patients with pleural mesothelioma

This study examined the p16 expression status and the P16 gene deletion and methylation status in specimens from Japanese patients with malignant pleural mesothelioma (MPM). Immunohistochemical staining for p16 protein and fluorescence in situ hybridization for the P16 gene were performed using specimens from 30 Japanese patients with primary MPM. The methylation status of the P16 gene was examined in 13 patients whose frozen tumor specimens were available using a methylation-specific PCR assay. Among the 30 patients, the loss of p16 protein expression was observed in 24 patients (80.0%). Twenty-one patients had homozygous deletions, and 9 patients retained the P16 gene. None of the patients with P16 homozygous deletions exhibited p16-positive expression, and 3 patients who retained the P16 gene did not exhibit p16-positive expression. Aberrant P16 methylation was present in two patients with an intact P16 gene but without p16 expression. These results suggest that either a homozygous deletion or methylation is responsible for P16 inactivation. Regarding the prognosis, patients with p16-negative expression had a significantly shorter survival time than those with p16-positive expression (P=0.040). Our study showed that P16 inactivation by homozygous deletions or methylation is a frequent event in Japanese patients with MPMs, relating to poor prognosis. Homozygous deletion is the major cause of P16 inactivation, but methylation also lead to the inactivation of P16 when the P16 alleles are retained.

CD26 Overexpression Is Associated with Prolonged Survival and Enhanced Chemosensitivity in Malignant Pleural Mesothelioma

Purpose: Malignant pleural mesothelioma (MPM) is an aggressive and therapy-resistant neoplasm arising from the pleural mesothelial cells, without established indicators to predict responsiveness to chemotherapy. Experimental Design: Our study involving 79 MPM patients showed that 73.4% of MPM expressed CD26 on cell membrane. Results: The majority of epithelioid and biphasic types of MPM expressed CD26 on the cell membrane, whereas the sarcomatoid type showed a lack of CD26 surface expression. Although the sarcomatoid type was associated with poor prognosis (P < 0.0001), no significant relationship between CD26 expression and survival was observed. On the contrary, there was a trend for an association between response rate to chemotherapy and CD26 expression (P = 0.053), with a higher level of CD26 expression more likely to be linked to better response to chemotherapy. Moreover, CD26 expression was a significant factor associated with improved survival in patients who received chemotherapy [median survival time (MST), 18.6 vs. 10.7 months, P = 0.0083]. Furthermore, CD26 expression was significantly associated with better prognosis in patients receiving non–pemetrexed-containing regimens (MST, 14.2 vs. 7.4 months, P = 0.0042), whereas there was no significant association between CD26 expression and survival time for patients receiving pemetrexed-containing regimens. Our in vitro and microarray studies showed that mesothelioma cells expressing high CD26 displayed high proliferative activity, and CD26 expression was closely linked to cell-cycle regulation, apoptosis, and chemotherapy resistance. Conclusions: Our results strongly suggest that CD26 is a clinically significant biomarker for predicting response to chemotherapy for MPM. Clin Cancer Res; 18(5); 1447–56. ©2012 AACR.

Aberrant DNA methylation profile in pleural fluid for differential diagnosis of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) usually develops pleural fluid. We investigated the value of DNA methylation in the pleural fluid for differentiating MPM from lung cancer (LC). Pleural fluid was collected from 39 patients with MPM, 46 with LC, 25 with benign asbestos pleurisy (BAP) and 30 with other causes. The methylation of O6‐methylguanine‐DNA methyltransferase (MGMT), p16INK4a, ras association domain family 1A (RASSF1A), death‐associated protein kinase (DAPK), and retinoic acid receptor β (RARβ) was examined using quantitative real‐time PCR. DNA methylation of RASSF1A, p16INK4a, RARβ, MGMT and DAPK was detected in 12 (30.8%), 3 (7.7%), 11 (28.2%), 0 (0.0%) and five patients (12.8%) with MPM, and in 22 (47.8%), 14 (30.4%), 24 (52.2%), 1 (2.2%) and six patients (13.0%) with LC, respectively. The mean methylation ratios of RASSF1A, p16INK4a and RARβ were 0.37 (range 0.0–2.84), 0.11 (0.0–2.67) and 0.44 (0.0–3.32) in MPM, and 0.87 (0.0–3.14), 1.16 (0.0–5.35) and 1.69 (0.0–6.49) in LC, respectively. The methylation ratios for the three genes were significantly higher in LC than in MPM (RASSF1A, P = 0.039; p16INK4a, P = 0.005; and RARβ, P = 0.002). Patients with methylation in at least one gene were 3.51 (95% confidence interval, 1.09–11.34) times more likely to have LC. Hypermethylation seemed no greater with MPM than with BAP. Extended exposure to asbestos (≧30 years) was correlated with an increased methylation frequency (P = 0.020). Hypermethylation of tumor suppressor genes in pleural fluid DNA has the potential to be a valuable marker for differentiating MPM from LC. (Cancer Sci 2012; 103: 510–514)