Genome-wide association studies have highlighted three major lung cancer susceptibility regions at 15q25.1, 5p15.33 and 6p21.33. To gain insight into the possible mechanistic relevance of the genes in these regions, we investigated the regulation of candidate susceptibility gene expression by epigenetic alterations in healthy and lung tumor tissues. For genes up or downregulated in lung tumors, the influence of genetic variants on DNA methylation was investigated and in vitro studies were performed. We analyzed 394 CpG units within 19 CpG islands in the susceptibility regions in a screening set of 34 patients. Significant findings were validated in an independent patient set (n=50) with available DNA and RNA. The most consistent overall DNA methylation difference between tumor and adjacent normal tissue on 15q25 was tumor hypomethylation in the promoter region of CHRNB4 with a median difference of 8% (P<0.001), which resulted in overexpression of the transcript in tumors (P<0.001). Confirming previous studies, we also found hypermethylation in CHRNA3 and telomerase reverse transcriptase (TERT) with significant expression changes. Decitabine treatment of H1299 cells resulted in reduced methylation levels in gene promoters, elevated transcript levels of CHRNB4 and CHRNA3, and a slight downregulation of TERT demonstrating epigenetic regulation of lung cancer cells. Single-nucleotide polymorphisms rs421629 on 5p15.33 and rs1948, rs660652, rs8040868 and rs2036527 on 15q25.1, previously identified as lung cancer risk or nicotine-addiction modifiers, were associated with tumor DNA methylation levels in the promoters of TERT and CHRNB4 (P<0.001), respectively, in two independent sample sets (n=82; n=150). In addition, CHRNB4 knockdown in two different cell lines (A549 and H1299) resulted in reduced proliferation (PA549<0.05;PH1299<0.001) and propensity to form colonies in H1299 cells. These results suggest epigenetic deregulation of nicotinic acetylcholine receptor subunit (nAChR) genes which in the case of CHRNB4 is strongly associated with genetic lung cancer susceptibility variants and a functional impact on tumorigenic potential.

Importance of growth factor (GF) signaling in cancer progression is widely acknowledged. Transforming growth factor beta (TGFβ) is known to play a key role in epithelial-to-mesenchymal transition (EMT) and metastatic cell transformation that are characterized by alterations in cell mechanical architecture and behavior towards a more robust and motile single cell phenotype. However, mechanisms mediating cancer type specific enhancement of cell mechanical phenotype in response to TGFβ remain poorly understood. Here, we combine high-throughput mechanical cell phenotyping, microarray analysis and gene-silencing to dissect cytoskeletal mediators of TGFβ-induced changes in mechanical properties of on-small-cell lung carcinoma (NSCLC) cells. Our experimental results show that elevation of rigidity and invasiveness of TGFβ-stimulated NSCLC cells correlates with upregulation of several cytoskeletal and motor proteins including vimentin, a canonical marker of EMT, and less-known unconventional myosins. Selective probing of gene-silenced cells lead to identification of unconventional myosin MYH15 as a novel mediator of elevated cell rigidity and invasiveness in TGFβ-stimulated NSCLC cells. Our experimental results provide insights into TGFβ-induced cytoskeletal remodeling of NSCLC cells and suggest that mediators of elevated cell stiffness and migratory activity such as unconventional cytoskeletal and motor proteins may represent promising pharmaceutical targets for restraining invasive spread of lung cancer.

Upon severe DNA damage a cellular signalling network initiates a cell death response through activating tumour suppressor p53 in association with promyelocytic leukaemia (PML) nuclear bodies. The deacetylase Sirtuin 1 (SIRT1) suppresses cell death after DNA damage by antagonizing p53 acetylation. To facilitate efficient p53 acetylation, SIRT1 function needs to be restricted. How SIRT1 activity is regulated under these conditions remains largely unclear. Here we provide evidence that SIRT1 activity is limited upon severe DNA damage through phosphorylation by the DNA damage-responsive kinase HIPK2. We found that DNA damage provokes interaction of SIRT1 and HIPK2, which phosphorylates SIRT1 at Serine 682 upon lethal damage. Furthermore, upon DNA damage SIRT1 and HIPK2 colocalize at PML nuclear bodies, and PML depletion abrogates DNA damage-induced SIRT1 Ser682 phosphorylation. We show that Ser682 phosphorylation inhibits SIRT1 activity and impacts on p53 acetylation, apoptotic p53 target gene expression and cell death. Mechanistically, we found that DNA damage-induced SIRT1 Ser682 phosphorylation provokes disruption of the complex between SIRT1 and its activator AROS. Our findings indicate that phosphorylation-dependent restriction of SIRT1 activity by HIPK2 shapes the p53 response.

Ubiquitin-dependent sorting of membrane proteins in endosomes directs them to lysosomal degradation. In the case of receptors such as the epidermal growth factor receptor (EGFR), lysosomal degradation is important for the regulation of downstream signalling. Ubiquitinated proteins are recognised in endosomes by the endosomal sorting complexes required for transport (ESCRT) complexes, which sequentially interact with the ubiquitinated cargo. Although the role of each ESCRT complex in sorting is well established, it is not clear how the cargo is passed on from one ESCRT to the next. We here show that flotillin-1 is required for EGFR degradation, and that it interacts with the subunits of ESCRT-0 and -I complexes (hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) and Tsg101). Flotillin-1 is required for cargo recognition and sorting by ESCRT-0/Hrs and for its interaction with Tsg101. In addition, flotillin-1 is also required for the sorting of human immunodeficiency virus 1 Gag polyprotein, which mimics ESCRT-0 complex during viral assembly. We propose that flotillin-1 functions in cargo transfer between ESCRT-0 and -I complexes.

Current understanding suggests that mammalian rod photoreceptors connect only to an ON-type bipolar cell. This rod-specific bipolar cell excites the All amacrine cell, which makes connections to cone-specific bipolar cells of both ON and OFF type; these, in turn, synapse with ganglion cells. Recent work on rabbit retina has shown that rod signals can also reach ganglion cells without passing through the rod bipolar cell. This route was thought to be provided by electrical gap junctions, through which rods signal directly to cones and thence to cone bipolar cells. Here, we show that the mouse retina also provides a rod pathway bypassing the rod bipolar cell, suggesting that this is a common feature in mammals. However, this alternative pathway does not require cone photoreceptors; it is perfectly intact in a transgenic mouse whose retina lacks cones. Instead, the results can be explained if rods connect directly to OFF bipolar cells.

The Drosophila domino gene has been isolated in a screen for mutations that cause hematopoietic disorders. Generation and analysis of loss-of-function domino alleles show that the phenotypes are typical for proliferation gene mutations. Clonal analysis demonstrates that domino is necessary for cell viability and proliferation, as well as for oogenesis. domino encodes two protein isoforms of 3202 and 2498 amino acids, which contain a common N-terminal region but divergent C termini. The common region includes a 500 amino acid DNA-dependent ATPase domain of the SWI2/SNF2 family of proteins, which function via interaction with chromatin. We show that, although domino alleles do not exhibit homeotic phenotypes by themselves, domino mutations enhance Polycomb group mutations and counteract Trithorax group effects. The Domino proteins are present in large complexes in embryo extracts, and one isoform binds to a number of discrete sites on larval polytene chromosomes. Altogether, the data lead us to propose that domino acts as a repressor by interfering with chromatin structure. This activity is likely to be performed as a subunit of a chromatin-remodeling complex.

Uncontrolled proliferation is a hallmark of malignant tumour growth. Its prognostic role in non-small cell lung cancer (NSCLC) has been investigated in numerous studies with controversial results. We aimed to resolve these controversies by assessing the Ki-67 proliferation index (PI) in three large, independent NSCLC cohorts.

In lung cancer a deregulation of Transforming Growth Factor-β (TGFβ) signaling has been observed. Yet, the impact of TGFβ in squamous cell carcinoma of the lung (LUSC) remained to be determined. We combined phenotypic and transcriptome-wide studies and showed that the stimulation of the LUSC cell line SK-MES1 with TGFβ results in an increase of migratory invasive properties. The analysis of the dynamics of gene expression by next-generation sequencing revealed that TGFβ stimulation orchestrates the upregulation of numerous motility- and actin cytoskeleton-related genes. Among these the non-muscle myosin 10 (MYO10) showed the highest upregulation in a LUSC patient cohort of the Cancer Genome Atlas (TCGA). Knockdown of MYO10 abrogated TGFβ-induced collagen gel invasion of SK-MES1 cells. The analysis of MYO10 mRNA expression in paired tissues of 151 LUSC patients with corresponding 80-month clinical follow-up data showed that the mRNA expression ratio of MYO10 in tumor and tumor-free tissue is prognostic for overall survival of LUSC patients and predictive for the response of these patients to adjuvant chemotherapy. Thus, MYO10 represents a new clinical biomarker for this aggressive disease and due to its role in cellular motility and invasion could serve as a potential molecular target for therapeutic interventions in patients with LUSC.

The advanced lung cancer inflammation index [ALI: body mass index × serum albumin/neutrophil-to-lymphocyte ratio (NLR)] reflects systemic host inflammation, and is easily reproducible. We hypothesized that ALI could assist guidance of non-small-cell lung cancer (NSCLC) treatment with immune checkpoint inhibitors (ICIs).