Taiichiro Otsuki

A3 adenosine receptor-mediated p53-dependent apoptosis in Lu-65 human lung cancer cells.

Background/Aims: A3 adenosine receptor mediates apoptosis in cancer cells via diverse signaling pathways. The present study examined A3 adenosine receptor-mediated apoptosis in Lu-65 cells, a human giant cell lung carcinoma cell line. Methods: MTT assay, TUNEL staining, real-time RT-PCR, Western blotting, and assay of caspase-3, -8, and -9 activities were carried out in Lu-65 cells, and A3 adenosine receptor or p53 was knocked-down by transfecting each siRNA into cells. Results: Extracellular adenosine induces Lu-65 cell apoptosis in a concentration (0.01-10 mM)-dependent manner, and the effect was inhibited by the A3 adenosine receptor inhibitor MRS1191 or by knocking-down A3 adenosine receptor or p53. Like adenosine, the A3 adenosine receptor agonist 2-Cl-IB-MECA also induced Lu-65 cell apoptosis. Adenosine upregulated expression of p53 and Noxa mRNAs and activated caspase-3 and -9, but not caspase-8. Those adenosine effects were still inhibited by knocking-down A3 adenosine receptor or p53. Conclusion: The results of the present study show that adenosine upregulates p53 expression via A3 adenosine receptor, to promote p53-dependent Noxa gene transcription, causing activation of caspase-9 and the effector caspase-3 to induce Lu-65 cell apoptosis.

Serum HMGB1 as a diagnostic marker for malignant peritoneal mesothelioma.

Background: Diffuse malignant peritoneal mesothelioma (DMPM) is an aggressive malignant tumor of mesothelial origin that shows a limited response to cytoreductive surgery along with intraperitoneal chemotherapy. Therefore, early diagnosis of DMPM is very important. Some researchers have previously reported that high-mobility group box 1 (HMGB1) was correlated with pulmonary fibrosis. DMPM involves the malignant transformation of mesothelial cells, which originate from mesenchymal cells, similar to lung fibroblasts. Here, we investigated serum levels of HMGB1 in patients with MPM and compared them with those of a population that had been exposed to asbestos without developing MPM. Study: The serum concentrations of HMGB1 were measured in 13 DMPM patients and 45 individuals with benign asbestos-related diseases. Result: We demonstrated that the patients with DMPM had significantly higher serum levels of HMGB1 compared with the population who had been exposed to asbestos but did not develop DMPM. Conclusion: Our data suggest that serum HMGB1 concentration is a useful serum marker for DMPM.

Biallelic germline and somatic mutations in malignant mesothelioma: Multiple mutations in transcription regulators including mSWI/SNF genes

We detected low levels of acetylation for histone H3 tail lysines in malignant mesothelioma (MM) cell lines resistant to histone deacetylase inhibitors. To identify the possible genetic causes related to the low histone acetylation levels, whole‐exome sequencing was conducted with MM cell lines established from eight patients. A mono‐allelic variant of BRD1 was common to two MM cell lines with very low acetylation levels. We identified 318 homozygous protein‐damaging variants/mutations (18–78 variants/mutations per patient); annotation analysis showed enrichment of the molecules associated with mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complexes and co‐activators that facilitate initiation of transcription. In seven of the patients, we detected a combination of variants in histone modifiers or transcription factors/co‐factors, in addition to variants in mSWI/SNF. Direct sequencing showed that homozygous mutations in SMARCA4, PBRM1 and ARID2 were somatic. In one patient, homozygous germline variants were observed for SMARCC1 and SETD2 in chr3p22.1–3p14.2. These exhibited extended germline homozygosity and were in regions containing somatic mutations, leading to a loss of BAP1 and PBRM1 expression in MM cell line. Most protein‐damaging variants were heterozygous in normal tissues. Heterozygous germline variants were often converted into hemizygous variants by mono‐allelic deletion, and were rarely homozygous because of acquired uniparental disomy. Our findings imply that MM might develop through the somatic inactivation of mSWI/SNF complex subunits and/or histone modifiers, including BAP1, in subjects that have rare germline variants of these transcription regulators and/or transcription factors/co‐factors, and in regions prone to mono‐allelic deletion during oncogenesis.

A new prognostic index for overall survival in malignant pleural mesothelioma: the rPHS (regimen, PS, histology or stage) index.

OBJECTIVE Existing prognostic indices for malignant pleural mesothelioma do not incorporate the recent advances in oncology care. The purpose of this study was to provide a prognostic index for overall survival in malignant pleural mesothelioma patients treated with chemotherapy with pemetrexed or best supportive care in the recent clinical setting. METHODS A retrospective cohort study was performed in two hospitals in Japan (2007-13). The primary outcome was overall survival. The Cox proportional hazards model was used for multivariable analyses to identify prognostic factors. A final model was chosen based on both clinical and statistical significance. RESULTS A total of 283 patients (chemotherapy: n = 228, best supportive care: n = 55) were enrolled in the study. On multivariate analysis, regimen including platinum plus pemetrexed, a performance status >0, non-epithelial histological type and Stage IV disease predicted poor overall survival in chemotherapy patients. As hazard ratios of individual risk factors were approximately similar, a prognostic index for overall survival was constructed by counting the risk factors. Median overall survival in chemotherapy patients decreased by each one-point increase in this count: 1030 days for zero; 658 days for one; 373 days for two; 327 days for three; 125 days for four. Internal validation using the bootstrapping technique showed robustness of the model (c-index, 0.677; 95% confidence interval, 0.624-0.729). Further, the discrimination was consistent in best supportive care patients (c-index, 0.799; 95% confidence interval, 0.725-0.874). CONCLUSIONS This novel index can provide clinicians and malignant pleural mesothelioma patients with a better framework for discussing prognosis at the time of diagnosis.

External validation of prognostic indices for overall survival of malignant pleural mesothelioma

OBJECTIVE There are several prognostic indices (PIs) to predict overall survival (OS) in malignant pleural mesothelioma (MPM) patients. Before using a clinical prediction model in the actual clinical setting, empiric evaluation of its performance based on datasets that were not used to develop the model (i.e., external validation) is essential. The purpose of this study was to conduct an external validation of the PIs for MPM. MATERIALS AND METHODS A retrospective cohort study was performed on MPM patients treated at 2 tertiary hospitals in Japan between 2007 and 2015. The primary outcome was OS. Harrells c-index, and was calculated to examine the discrimination of three models. The bootstrapping technique was used to evaluate optimism. RESULTS The participants comprised 183 patients who underwent surgical treatment (n=61), chemotherapy (n=101), and best supportive care (BSC, n=21). The median OS rates were 1014days for surgery, 690days for chemotherapy, and 545days for best supportive care (BSC). The respective discriminations (95% confidence interval) of the Eastern Cooperative Oncology Group Performance Status, the European Organisation for Research and Treatment of Cancer index, regimen, PS, histology or stage (rPHS) index, and Tagawa index for the OS of MPM patients were 0.532 (0.444-0.620), 0.560 (0.472-0.648), 0.584 (0.452-0.716), and 0.525 (0.453-0.596) for surgery; 0.632 (0.539-0.724), 0.622 (0.548-0.696), 0.677 (0.587-0.766), and 0.545 (0.436-0.653) for chemotherapy; and 0.504 (0.365-0.644), 0.583 (0.456--0.710), 0.704 (0.508-0.899), and 0.583 (0.436-0.730) for BSC. CONCLUSIONS Each PI showed poor discrimination for MPM patients who underwent surgical treatment. The rPHS index showed moderate discrimination for patients given chemotherapy and BSC.

Epithelioid pleural mesothelioma concurrently associated with miliary pulmonary metastases and minimal change nephrotic syndrome – A hitherto undescribed case

Malignant pleural mesothelioma (MPM) is the aggressive disease typically spreading along the pleural surface and encasing the lung, leading to respiratory failure or cachexia. Rare cases with atypical clinical manifestation or presentation have been reported in MPM. We experienced a unique case of MPM concurrently associated with miliary pulmonary metastases and nephrotic syndrome. A 73-year-old Japanese man with past history of asbestos exposure was referred to our hospital for the investigation of the left pleural effusion. Chest computed tomography showed thickening of the left parietal pleura. Biopsy specimen of the pleura showed proliferating epithelioid tumor cells, leading to the pathological diagnosis of epithelioid MPM with the aid of immunohistochemistry. After the diagnosis of MPM, chemotherapy was performed without effect. Soon after the clinical diagnosis of progressive disease with skull metastasis, edema and weight gain appeared. Laboratory data met the criteria of nephrotic syndrome, and renal biopsy with electron microscopic examination revealed the minimal change disease. Steroid therapy was started but showed no effect. Around the same time of onset of nephrotic syndrome, multiple miliary lung nodules appeared on chest CT. Transbronchial biopsy specimen of the nodules showed the metastatic MPM in the lung. The patient died because of the worsening of the general condition. To our knowledge, this is the first case of MPM concurrently associated with multiple miliary pulmonary metastases and nephrotic syndrome.

1558PA NEW PROGNOSTIC INDEX FOR OVERALL SURVIVAL IN MALIGNANT PLEURAL MESOTHELIOMA

ABSTRACT Aim: Existing prognostic indices for malignant pleural mesothelioma (MPM) do not incorporate recent advances in oncology care and were not based on real-world clinical data. This study aimed to provide a prognostic index for overall survival (OS) in MPM patients receiving chemotherapy with pemetrexed (CTx) or best supportive care (BSC) in a present, real-world setting. Methods: A retrospective cohort study was performed using MPM patients treated in two tertiary hospitals in Japan between 2007 and 2013. The prognostic index was developed using CTx patients, then diagnostic performance of the index was evaluated in both CTx and BSC patients. The primary outcome was OS. The Cox proportional hazards model was used for multivariable analyses to detect prognostic factors. A final model was chosen based on both clinical and statistical significance. Harrells c index was calculated to examine the discrimination of the model. The bootstrapping technique was used for internal validation. Results: Participants comprised 283 patients (CTx, n=228; BSC, n=55). On multivariate Cox proportional regression analysis, risk factors for poor prognosis of OS for CTx patients included performance status >0, non-epithelial histological type, and stage IV disease. Since hazard ratios of individual risk factors ranged from 1.81 to 2.07, a prognostic index for OS was constructed using a simple count of the number of risk factors (PHS index). Median OS in CTx patients was shortened by each 1-point increase in PHS index: 948 days (95% confidence interval (CI), 884–1012 days) for score 0; 544 days (95%CI, 526–561 days) for 1; 362 days (95%CI, 347–375 days) for 2; and 214 days (95%CI, 186–242 days) for 3. Internal validation showed the model was robust (c index, 0.670; 95%CI, 0.619–0.721). Median OS for each PHS index with BSC was: 573 days (95%CI, not evaluable (NE) - NE) for 0; 402 days (95%CI, 370–434 days) for 1; 94 days (95%CI, 82–105 days) for 2; and 34 days (95%CI, 15–52 days) for 3. Discrimination was consistent in BSC patients (c-index, 0.799; 95%CI, 0.725–0.874). Conclusions: This index will provide clinicians and patients with a better framework for discussing prognosis at the time of diagnosis. Disclosure: All authors have declared no conflicts of interest.