Predictive Genes in Adjacent Normal Tissue Are Preferentially Altered by sCNV during Tumorigenesis in Liver Cancer and May Rate Limiting

Background: In hepatocellular carcinoma (HCC) genes predictive of survival have been found in both adjacent normal (AN) and tumor (TU) tissues. The relationships between these two sets of predictive genes and the general process of tumorigenesis and disease progression remains unclear. Methodology/Principal Findings: Here we have investigated HCC tumorigenesis by comparing gene expression, DNA copy number variation and survival using ~250 AN and TU samples representing, respectively, the pre-cancer state, and the result of tumorigenesis. Genes that participate in tumorigenesis were defined using a gene-gene correlation meta-analysis procedure that compared AN versus TU tissues. Genes predictive of survival in AN (AN-survival genes) were found to be enriched in the differential gene-gene correlation gene set indicating that they directly participate in the process of tumorigenesis. Additionally the AN-survival genes were mostly not predictive after tumorigenesis in TU tissue and this transition was associated with and could largely be explained by the effect of somatic DNA copy number variation (sCNV) in cis and in trans. The data was consistent with the variance of AN-survival genes being rate-limiting steps in tumorigenesis and this was confirmed using a treatment that promotes HCC tumorigenesis that selectively altered AN-survival genes and genes differentially correlated between AN and TU. Conclusions/Significance: This suggests that the process of tumor evolution involves rate-limiting steps related to the background from which the tumor evolved where these were frequently predictive of clinical outcome. Additionally treatments that alter the likelihood of tumorigenesis occurring may act by altering AN-survival genes, suggesting that the process can be manipulated. Further sCNV explains a substantial fraction of tumor specific expression and may therefore be a causal driver of tumor evolution in HCC and perhaps many solid tumor types. © 2011 Lamb et al.published_or_final_versio

p62/SQSTM1 enhances breast cancer stem-like properties by stabilizing MYC mRNA

Aberrant p62 overexpression has been implicated in breast cancer development. Here, we found that p62 expression was elevated in breast cancer stem cells (BCSCs), including CD44+CD24− fractions, mammospheres, ALDH1+ populations and side population cells. Indeed, short-hairpin RNA (shRNA)-mediated knockdown of p62 impaired breast cancer cells from self-renewing under anchorage-independent conditions, whereas ectopic overexpression of p62 enhanced the self-renewal ability of breast cancer cells in vitro. Genetic depletion of p62 robustly inhibited tumor-initiating frequencies, as well as growth rates of BCSC-derived tumor xenografts in immunodeficient mice. Consistently, immunohistochemical analysis of clinical breast tumor tissues showed that high p62 expression levels were linked to poorer clinical outcome. Further gene expression profiling analysis revealed that p62 was positively correlated with MYC expression level, which mediated the function of p62 in promoting breast cancer stem-like properties. MYC mRNA level was reduced upon p62 deletion by siRNA and increased with p62 overexpression in breast cancer cells, suggesting that p62 positively regulated MYC mRNA. Interestingly, p62 did not transactivate MYC promoter. Instead, p62 delayed the degradation of MYC mRNA by repressing the expression of let-7a and let-7b, thus promoting MYC mRNA stabilization at the post-transcriptional level. Consistently, let-7a and let-7b mimics attenuated p62-mediated MYC mRNA stabilization. Together, these findings unveiled a previously unappreciated role of p62 in the regulation of BCSCs, assigning p62 as a promising therapeutic target for breast cancer treatments

The Acinetobacter Trimeric Autotransporter Adhesin Ata Controls Key Virulence Traits of Acinetobacter baumannii

Introduction: Acinetobacter baumannii is a Gram-negative pathogen that causes a multitude of nosocomial infections. The Acinetobacter trimeric autotransporter adhesin (Ata) belongs to the superfamily of trimeric autotransporter adhesins which are important virulence factors in many Gram-negative species.Objective: We evaluated the impact of Ata in host-pathogen interaction by analysing adhesion, invasion, host-cell-modulation and apoptosis in human endothelial and epithelial cells.Materials and Methods: Adhesion of A. baumannii to human host cells was investigated using primary endothelial and epithelial cells under static and dynamic flow conditions. Furthermore, an ex vivo organ infection model employing human umbilical cord veins was employed. Host cell invasion was analysed by a gentamicin protection assay. Induction of apoptosis was determined using propidium iodide/annexin V staining with subsequent FACS analysis and the Caspase-Glo assay (Promega). Chemokine secretion upon infection was analysed using Multi-Analyte ELISArray Kits (Qiagen). Pathogenicity in vivo was evaluated using the Galleria mellonella infection model.Result: Phylogenetic profiling using 3,052 Acinetobacter spp. genomes revealed that ata is present in 78% of all A. baumannii isolates but only in 2% of the closely related but less pathogenic species A. calcoaceticus and A. pittii. Employing a markerless ata deletion mutant of A. baumannii ATCC 19606 and complemented controls, we could show that adhesion to and invasion into human endothelial and epithelial cells under static conditions both clearly depend on Ata. This adhesion defect was even more evident when dynamic infection conditions were applied or when human umbilical cord veins were infected ex vivo with A. baumannii. Infection of primary human umbilical cord vein endothelial cells (HUVECs) with A. baumannii led to the secretion of the pro-inflammatory cytokines interleukin (IL)-6 and IL-8 in a time- and Ata-dependent manner. Ata induced apoptosis, but not necrosis, of HUVECs after 16 h post infection by activation of caspase-3 and caspase-7. Ata deletion mutants were furthermore attenuated in their ability to kill larvae of G. mellonella and to survive in larvae when injected at sublethal doses.Conclusion: These results strongly suggest that Ata is an important multifunctional virulence factor of A. baumannii that triggers multiple important steps for the initiation of successful infections in different host cells