We have sequenced the genomes of 110 small cell lung cancers (SCLC), one of the deadliest human cancers. In nearly all the tumours analysed we found bi-allelic inactivation of TP53 and RB1, sometimes by complex genomic rearrangements. Two tumours with wild-type RB1 had evidence of chromothripsis leading to overexpression of cyclin D1 (encoded by the CCND1 gene), revealing an alternative mechanism of Rb1 deregulation. Thus, loss of the tumour suppressors TP53 and RB1 is obligatory in SCLC. We discovered somatic genomic rearrangements of TP73 that create an oncogenic version of this gene, TP73Δex2/3. In rare cases, SCLC tumours exhibited kinase gene mutations, providing a possible therapeutic opportunity for individual patients. Finally, we observed inactivating mutations in NOTCH family genes in 25% of human SCLC. Accordingly, activation of Notch signalling in a pre-clinical SCLC mouse model strikingly reduced the number of tumours and extended the survival of the mutant mice. Furthermore, neuroendocrine gene expression was abrogated by Notch activity in SCLC cells. This first comprehensive study of somatic genome alterations in SCLC uncovers several key biological processes and identifies candidate therapeutic targets in this highly lethal form of cancer.

We identified in-frame fusion transcripts of KIF5B (the kinesin family 5B gene) and the RET oncogene, which are present in 1-2% of lung adenocarcinomas (LADCs) from people from Japan and the United States, using whole-transcriptome sequencing. The KIF5B-RET fusion leads to aberrant activation of RET kinase and is considered to be a new driver mutation of LADC because it segregates from mutations or fusions in EGFR, KRAS, HER2 and ALK, and a RET tyrosine kinase inhibitor, vandetanib, suppresses the fusion-induced anchorage-independent growth activity of NIH3T3 cells.

Activation of the EGFR, KRAS, and ALK oncogenes defines 3 different pathways of molecular pathogenesis in lung adenocarcinoma. However, many tumors lack activation of any pathway (triple-negative lung adenocarcinomas) posing a challenge for prognosis and treatment. Here, we report an extensive genome-wide expression profiling of 226 primary human stage I-II lung adenocarcinomas that elucidates molecular characteristics of tumors that harbor ALK mutations or that lack EGFR, KRAS, and ALK mutations, that is, triple-negative adenocarcinomas. One hundred and seventy-four genes were selected as being upregulated specifically in 79 lung adenocarcinomas without EGFR and KRAS mutations. Unsupervised clustering using a 174-gene signature, including ALK itself, classified these 2 groups of tumors into ALK-positive cases and 2 distinct groups of triplenegative cases (groups A and B). Notably, group A triple-negative cases had a worse prognosis for relapse and death, compared with cases with EGFR, KRAS, or ALK mutations or group B triple-negative cases. In ALK-positive tumors, 30 genes, including ALK and GRIN2A, were commonly overexpressed, whereas in group A triple-negative cases, 9 genes were commonly overexpressed, including a candidate diagnostic/therapeutic target DEPDC1, that were determined to be critical for predicting a worse prognosis. Our findings are important because they provide a molecular basis of ALK-positive lung adenocarcinomas and triple-negative lung adenocarcinomas and further stratify more or less aggressive subgroups of triple-negative lung ADC, possibly helping identify patients who may gain the most benefit from adjuvant chemotherapy after surgical resection. Cancer Res; 72(1); 100-11. Ó2011 AACR.

PurposeExosomal microRNAs (miRNAs) have been attracting major interest as potential diagnostic biomarkers of cancer. The aim of this study was to characterize the miRNA profiles of serum exosomes and to identify those that are altered in colorectal cancer (CRC). To evaluate their use as diagnostic biomarkers, the relationship between specific exosomal miRNA levels and pathological changes of patients, including disease stage and tumor resection, was examined.Experimental DesignMicroarray analyses of miRNAs in exosome-enriched fractions of serum samples from 88 primary CRC patients and 11 healthy controls were performed. The expression levels of miRNAs in the culture medium of five colon cancer cell lines were also compared with those in the culture medium of a normal colon-derived cell line. The expression profiles of miRNAs that were differentially expressed between CRC and control sample sets were verified using 29 paired samples from post-tumor resection patients. The sensitivities of selected miRNAs as biomarkers of CRC were evaluated and compared with those of known tumor markers (CA19-9 and CEA) using a receiver operating characteristic analysis. The expression levels of selected miRNAs were also validated by quantitative real-time RT-PCR analyses of an independent set of 13 CRC patients.ResultsThe serum exosomal levels of seven miRNAs (let-7a, miR-1229, miR-1246, miR-150, miR-21, miR-223, and miR-23a) were significantly higher in primary CRC patients, even those with early stage disease, than in healthy controls, and were significantly down-regulated after surgical resection of tumors. These miRNAs were also secreted at significantly higher levels by colon cancer cell lines than by a normal colon-derived cell line. The high sensitivities of the seven selected exosomal miRNAs were confirmed by a receiver operating characteristic analysis.ConclusionExosomal miRNA signatures appear to mirror pathological changes of CRC patients and several miRNAs are promising biomarkers for non-invasive diagnosis of the disease.

The hOGG1 gene encodes a DNA glycosylase that excises 8-hydroxyguanine (oh 8 Gua) from damaged DNA. Structural analyses of the hOGG1 gene and its transcripts were performed in normal and lung cancer cells. Due to a genetic polymorphism at codon 326, hOGG1-Ser 326 and hOGG1-Cys 326 proteins were produced in human cells. Activity in the repair of oh 8 Gua was greater in hOGG1-Ser 326 protein than in hOGG1-Cys 326 protein in the complementation assay of an E. coli mutant defective in the repair of oh 8 Gua. Two isoforms of hOGG1 transcripts produced by alternative splicing encoded distinct hOGG1 proteins: one with and the other without a putative nuclear localization signal. Loss of heterozygosity at the hOGG1 locus was frequently (15/ 23, 62.2%) detected in lung cancer cells, and a cell line NCI-H526 had a mutation leading to the formation of the transcripts encoding a truncated hOGG1 protein. However, the oh 8 Gua levels in nuclear DNA were similar among lung cancer cells and leukocytes irrespective of the type of hOGG1 proteins expressed. These results suggest that the oh 8 Gua levels are maintained at a steady level, even though multiple hOGG1 proteins are produced due to genetic polymorphisms, mutations and alternative splicing of the hOGG1 gene.

Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs) generated by ionizing radiation (IR) and anti-cancer drugs. Therefore, inhibiting the activity of proteins involved in this pathway is a promising way of sensitizing cancer cells to both radiotherapy and chemotherapy. In this study, we developed an assay for evaluating NHEJ activity against DSBs in chromosomal DNA in human cells to identify the chromatin modification/remodeling proteins involved in NHEJ. We showed that ablating the activity of the homologous histone acetyltransferases, CBP and p300, using inhibitors or small interfering RNAs-suppressed NHEJ. Ablation of CBP or p300 impaired IR-induced DSB repair and sensitized lung cancer cells to IR and the anti-cancer drug, etoposide, which induces DSBs that are repaired by NHEJ. The CBP/p300 proteins were recruited to sites of DSBs and their ablation suppressed acetylation of lysine 18 within histone H3, and lysines 5, 8, 12, and 16 within histone H4, at the DSB sites. This then suppressed the recruitment of KU70 and KU80, both key proteins for NHEJ, to the DSB sites. Ablation of CBP/p300 also impaired the recruitment of BRM, a catalytic subunit of the SWI/SNF complex involved in chromatin remodeling at DSB sites. These results indicate that CBP and p300 function as histone H3 and H4 acetyltransferases at DSB sites in NHEJ and facilitate chromatin relaxation. Therefore, inhibition CBP and p300 activity may sensitize cancer cells to radiotherapy and chemotherapy.

Background: Successful multimodality management of advanced soft tissue sarcomas (STS) remains a clinical challenge. Although immune checkpoint blockade has shown great promise, only a minority of patients respond. Improved biomarkers could benefit the treatment choice, since cytotoxic therapies and radiotherapy (RT) can alter the immune milieu. The objective of this study was to characterize PD-L1 expression in locally advanced STS with or without preoperative RT. Design: Tissue microarrays (TMA) were constructed using formalin-fixed, paraffin-embedded STS cases (N=17). A composite H-scoring system was applied to analyze/ quantify the protein expression. TMA sections were immunostained using a rabbit anti-human PD-L1 antibody (Sino Biological, Clone: 015). The intensity and percentage of PDL-1-positive cells were calculated and scored blindly. Patients were categorized into PD-L1 high and low-expressing based on H-score above or below the median. Parametric and non-parametric statistics were used as appropriate. Results: Mean age was 55±21, 82% were female, and 53% of STS tumors were located on the extremity. Median tumor size was 15.5 cm (range 2.4-24.8 cm). Half of the cases received preoperative RT. We observed 9 recurrences, and 5 sarcoma deaths. Overall, PD-L1 expression was significantly lower among RT patients (62.5±23.1 vs 139±90.5, p=0.04), and tumor stem cell markers EGFR/CD44 were also significantly lower among chemotherapy patients (p < 0.05). Distant recurrences were more common in PDL-1 high patients (5/8, 62%) than PDL-1 low patients (2/9, 22%). Conclusions: RT is associated with decreased PD-L1 expression in locally advanced STS, and lower PD-L1 expression is associated with improved longterm outcome. The modulation of PDL-1 expression by RT and the impact on prognosis in STS warrants further study. Background: Dedifferentiated liposarcoma (DDLPS) sometimes exhibit heterologous differentiation, and its influence on prognostic outcome is still controversial. As for ossification, it is also not clear whether the bone component means heterologous differentiation or it can be formed by reactive (non-neoplastic) mesenchymal cells. We aimed to investigate the neoplastic nature of the bones formed in DDLPS, and make clear the clinical and pathological characteristics of DDLPS with ossification. Design: We examined 27 cases of DDLPS with ossification by comparing them with 24 cases of DDLPS without ossification and 17 cases of primary extraskeletal osteosarcoma (ESOS) without MDM2 amplification or overexpression. The clinical and pathological findings were reviewed. Histological grade was determined using 'modified' FNCLCC grading system proposed before emphasizing the importance of tumor differentiation scoring. Results: MDM2 amplification was confirmed in osteocytes and/or osteoblastic cells in all DDLPS cases with ossification where Fluorescence In-Situ Hybridization (FISH) was successfully performed in bone forming area (22/22). The bones found in DDLPS were mainly mature in most cases (20/27), and ...

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