Classification and characterization of alternative promoters in 26 lung adenocarcinoma cell lines.

BACKGROUND: Genome-wide landscape of alternative promoter use remains unknown. We determined expression profiles of promoters in 26 lung adenocarcinoma cell lines using the transcriptional start site-sequencing data and proposed an index 'canonical promoter usage' to quantify the diversity of alternative promoter usage. METHODS: Transcriptional start site-sequencing and other datasets were obtained from the DataBase of Transcriptional Start Sites. Transcriptional start site-sequencing read clusters were mapped onto RefGene to determine the promoters. Commonly used promoters were designated as canonical promoters. The sequence logos, CpG islands, DNA methylation and histone modifications of canonical and non-canonical promoters were examined. Canonical promoter usage was calculated by dividing 'read counts of a canonical promoter' by 'read counts of all the units of promoters' on each gene. The expressed genes were subjected to hierarchical clustering according to their canonical promoter usage. RESULTS: Among 104 455 promoters for 14 297 genes, 8659 canonical and 68 197 non-canonical promoters were identified. Corresponding to higher expression, canonical promoters showed core promoter sequences, higher CpG island positivity, less DNA methylation and higher transcription-promoting histone modifications. Gene ontology enrichment analysis revealed that the clusters with lower canonical promoter usage were related to signalling pathways, whereas clusters of tightly regulated genes with higher canonical promoter usage were related to housekeeping genes. CONCLUSION: Canonical promoters were regulated by conventional transcriptional machinery, while non-canonical promoters would be targets of 'leaky' expression. Further investigation is warranted to analyse the correlation between alternative promoter usage and biological characteristics contributing to carcinogenesis.

Transposable elements potentiate radiotherapy-induced cellular immune reactions via RIG-I-mediated virus-sensing pathways.

Radiotherapy (RT) plus immunotherapy is a promising modality; however, the therapeutic effects are insufficient, and the molecular mechanism requires clarification to further develop combination therapies. Here, we found that the RNA virus sensor pathway dominantly regulates the cellular immune response in NSCLC and ESCC cell lines. Notably, transposable elements (TEs), especially long terminal repeats (LTRs), functioned as key ligands for the RNA virus sensor RIG-I, and the mTOR-LTR-RIG-I axis induced the cellular immune response and dendritic cell and macrophage infiltration after irradiation. Moreover, RIG-I-dependent immune activation was observed in ESCC patient tissue. scRNA sequencing and spatial transcriptome analysis revealed that radiotherapy induced the expression of LTRs, and the RNA virus sensor pathway in immune and cancer cells; this pathway was also found to mediate tumour conversion to an immunological hot state. Here, we report the upstream and ligand of the RNA virus sensor pathway functions in irradiated cancer tissues.

Fecal microbiota in patients with a stoma decreases anaerobic bacteria and alters taxonomic and functional diversities.

Colorectal cancer (CRC) is one of the most common malignant diseases. Generally, stoma construction is performed following surgery for the resection of the primary tumor in patients with CRC. The association of CRC with the gut microbiota has been widely reported, and the gut microbiota is known to play an important role in the carcinogenesis, progression, and treatment of CRC. In this study, we compared the microbiota of patients with CRC between with and without a stoma using fecal metagenomic sequencing data from SCRUM-Japan MONSTAR-SCREEN, a joint industry-academia cancer research project in Japan. We found that the composition of anaerobes was reduced in patients with a stoma. In particular, the abundance of Alistipes, Akkermansia, Intestinimonas, and methane-producing archaea decreased. We also compared gene function (e.g., KEGG Orthology and KEGG pathway) and found that gene function for methane and short-chain fatty acids (SCFAs) production was underrepresented in patients with a stoma. Furthermore, a stoma decreased Shannon diversity based on taxonomic composition but increased that of the KEGG pathway. These results suggest that the feces of patients with a stoma have a reduced abundance of favorable microbes for cancer immunotherapy. In conclusion, we showed that a stoma alters the taxonomic and functional profiles in feces and may be a confounding factor in fecal microbiota analysis.