Adenocarcinoma in situ and minimally invasive adenocarcinoma are the pre-invasive forms of lung adenocarcinoma. The genomic and immune profiles of these lesions are poorly understood. Here we report exome and transcriptome sequencing of 98 lung adenocarcinoma precursor lesions and 99 invasive adenocarcinomas. We have identified EGFR, RBM10, BRAF, ERBB2, TP53, KRAS, MAP2K1 and MET as significantly mutated genes in the pre/minimally invasive group. Classes of genome alterations that increase in frequency during the progression to malignancy are revealed. These include mutations in TP53, arm-level copy number alterations, and HLA loss of heterozygosity. Immune infiltration is correlated with copy number alterations of chromosome arm 6p, suggesting a link between arm-level events and the tumor immune environment.

PurposeTyrosine kinase inhibitors (TKIs) are widely used to treat lung adenocarcinoma patients with EGFR mutations or ALK-fusions. However, patients with wild-type genes or TKIs-resistant mutations lack effective therapeutic targets. Extensive studies reveal that super enhancer (SE), a large cis-regulatory element, is associated with key oncogenes in a variety of cancers. By comparing the effect of SE on lung adenocarcinoma cell lines with normal cell line, this work attempts to find new biomarkers and potential therapeutic targets for lung adenocarcinoma.Experimental DesignChromatin Immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq) of H3K27ac (acetylation on lysine 27 of histone 3) was performed in lung adenocarcinoma cell lines SPC-A1 and SCH-1153. The differences in SE distribution were then analyzed among SPC-A1, SCH-1153, A549 and normal human lung fibroblasts (NHLF) to identify SE-associated oncogenes. The expression of SE-associated oncogenes was then detected by RNA-seq and further verified in 71 patients by real-time PCR.ResultsSE associated with many new oncogenes in lung adenocarcinoma, among which, RAI14 was up-regulated in A549 and 31 of 71 patients. High expression of RAI14 could inhibit cell proliferation, indicating its potential as a new biomarker for lung adenocarcinoma.

As the most abundant noncoding RNA in cells, tRNA plays an important role in tumorigenesis and development. The report of tRNA on the pathogenesis of lung adenocarcinoma is rare. It is of great clinical significance to explore the relationship between tRNA expression and prognosis of lung adenocarcinoma. The expression level of tRNAs in lung adenocarcinoma tissues and paracarcinoma tissues was detected using a tRNA RT‐qPCR array. A total of 104 lung adenocarcinomas were included in the analysis of the correlation between candidate tRNAs expression and prognosis. A tRNA‐based prognostic model was constructed and validated using Cox proportional hazards regression. A nomogram was built to help clinicians develop treatment strategies. We screened a series of differentially expressed tRNAs between lung adenocarcinoma tissues and paracarcinoma tissues. Among these tRNAs, tRNAAsnATT, tRNAIleAAT, tRNALeuTAA, mt‐tRNATrpTCA, mt‐tRNALeuTAA, tRNAProAGG, tRNALysCTT‐1 and tRNALeuAAG were associated with the clinicopathological characteristics of lung adenocarcinoma. tRNALysCTT‐1, mt‐tRNASerGCT and tRNATyrATA were associated with cancer‐specific survival. We constructed a prognostic model for lung adenocarcinoma using specific tRNA expression levels as reference factors. Multivariate analyses showed that tRNA‐based prognostic score was a significant and important prognostic factor. The prognostic model based on the tRNAs expression signatures can help predict the prognosis of patients with lung adenocarcinoma.

Background Lung adenocarcinoma (LUAD) is a highly malignant and heterogeneous tumor that involves various oncogenic genetic alterations. Epigenetic processes play important roles in lung cancer development. However, the variation in enhancer and super-enhancer landscapes of LUAD patients remains largely unknown. To provide an in-depth understanding of the epigenomic heterogeneity of LUAD, we investigate the H3K27ac histone modification profiles of tumors and adjacent normal lung tissues from 42 LUAD patients and explore the role of epigenetic alterations in LUAD progression. Results A high intertumoral epigenetic heterogeneity is observed across the LUAD H3K27ac profiles. We quantitatively model the intertumoral variability of H3K27ac levels at proximal gene promoters and distal enhancers and propose a new epigenetic classification of LUAD patients. Our classification defines two LUAD subgroups which are highly related to histological subtypes. Group II patients have significantly worse prognosis than group I, which is further confirmed in the public TCGA-LUAD cohort. Differential RNA-seq analysis between group I and group II groups reveals that those genes upregulated in group II group tend to promote cell proliferation and induce cell de-differentiation. We construct the gene co-expression networks and identify group-specific core regulators. Most of these core regulators are linked with group-specific regulatory elements, such as super-enhancers. We further show that CLU is regulated by 3 group I-specific core regulators and works as a novel tumor suppressor in LUAD. Conclusions Our study systematically characterizes the epigenetic alterations during LUAD progression and provides a new classification model that is helpful for predicting patient prognosis.