Hirokazu Okayama

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 triple-negative 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.

Despite multidisciplinary treatment for patients with advanced gastric cancer, their prognosis remains poor. Therefore, the development of novel therapeutic strategies is urgently needed, and immunotherapy utilizing anti-programmed death 1/-programmed death ligand-1 mAb is an attractive approach. However, as there is limited information on how programmed death ligand-1 is upregulated on tumor cells within the tumor microenvironment, we examined the mechanism of programmed death ligand-1 regulation with a particular focus on interferon gamma in an in vitro setting and in clinical samples. Our in vitro findings showed that interferon gamma upregulated programmed death ligand-1 expression on solid tumor cells through the JAK-signal transducer and activator of transcription pathway, and impaired the cytotoxicity of tumor antigen-specific CTL against tumor cells. Following treatment of cells with anti-programmed death ligand-1 mAb after interferon gamma-pre-treatment, the reduced anti-tumor CTL activity by interferon gamma reached a higher level than the non-treatment control targets. In contrast, programmed death ligand-1 expression on tumor cells also significantly correlated with epithelial-mesenchymal transition phenotype in a panel of solid tumor cells. In clinical gastric cancer samples, tumor membrane programmed death ligand-1 expression significantly positively correlated with the presence of CD8-positive T cells in the stroma and interferon gamma expression in the tumor. The results suggest that gastric cancer patients with high CD8-positive T-cell infiltration may be more responsive to anti-programmed death 1/-programmed death ligand-1 mAb therapy.

During the last decade, it has become clear that aberrant microRNA expression has a functional role in the initiation and progression of colorectal cancer (CRC). Specific microRNAs can act as either tumor suppressors or oncogenes depending on the cellular environment in which they are expressed. The expression of microRNAs is reproducibly altered in CRC, and their expression patterns are associated with diagnosis, prognosis, and therapeutic outcome in CRC. Studies have begun to examine the association of microRNA-related polymorphisms and their association with CRC incidence and prognosis as well as the possibility of using circulating microRNAs or fecal microRNA expression as noninvasive early detection biomarkers. These data suggest that microRNAs may be potential molecular classifiers, early detection biomarkers, and therapeutic targets for CRC. Here, we will review the evidence demonstrating a role of microRNAs in CRC.

PURPOSE: To identify druggable oncogenic fusions in invasive mucinous adenocarcinoma (IMA) of the lung, a malignant type of lung adenocarcinoma in which KRAS mutations frequently occur. EXPERIMENTAL DESIGN: From an IMA cohort of 90 cases, consisting of 56 cases (62%) with KRAS mutations and 34 cases without (38%), we conducted whole-transcriptome sequencing of 32 IMAs, including 27 cases without KRAS mutations. We used the sequencing data to identify gene fusions, and then performed functional analyses of the fusion gene products. RESULTS: We identified oncogenic fusions that occurred mutually exclusively with KRAS mutations: CD74-NRG1, SLC3A2-NRG1, EZR-ERBB4, TRIM24-BRAF, and KIAA1468-RET. NRG1 fusions were present in 17.6% (6/34) of KRAS-negative IMAs. The CD74-NRG1 fusion activated HER2:HER3 signaling, whereas the EZR-ERBB4 and TRIM24-BRAF fusions constitutively activated the ERBB4 and BRAF kinases, respectively. Signaling pathway activation and fusion-induced anchorage-independent growth/tumorigenicity of NIH3T3 cells expressing these fusions were suppressed by tyrosine kinase inhibitors approved for clinical use. CONCLUSIONS: Oncogenic fusions act as driver mutations in IMAs without KRAS mutations, and thus represent promising therapeutic targets for the treatment of such IMAs.