Cupriavidus (Wautersia, Ralstonia, Alcaligenes) metallidurans strain CH34is a well-studied example of a metal-resistant proteobacterium. Genome sequence analysis revealed the presence of a variety of paralogs of proteins that were previously shown to be involved in heavy metal resistance. Which advantage has C. metallidurans in maintaining all these paralogs during evolution? Paralogs investigated belong to the families RND (resistance nodulation cell division) or CHR (chromate resistance). The respective genes were localized by PCR either on one of the two native megaplasmids pMOL28 and pMOL30 of strain CH34, or on its chromosomal DNA. Gene expression was studied by real-time reverse transcriptase PCR and by reporter gene constructs. Genes found to be inducible were disrupted and their contribution to metal resistance measured. When two or three highly related genes were present, usually one was inducible by heavy metals while the other one or two were silent or constitutively expressed. This suggests that C. metallidurans CH34 carries a variety of no longer or not yet used genes that might serve as surplus material for further developments, an advantage that may compensate for the costs of maintaining these genes during evolution.

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Lung adenocarcinoma is characterised by an upregulation of S100P, which mediates its function intracellularly but also extracellularly. Recent studies suggest that extracellular S100P contributes to tumour development following interaction with the receptor for advanced glycation end-products (RAGE). As RAGE is highly downregulated in lung cancer, one might speculate that S100P supports tumorigenesis via other pathways. Here, we showed that S100P primarily localises in the cytoplasmic and nuclear region as determined for lung adenocarcinoma specimens (immunohistochemistry) and H358 lung adenocarcinoma cells stably overexpressing S100P (GFP-S100P; fluorescence microscopy). S100P overexpression in H358 cells induced a more frequent formation of tumour colonies in vitro (soft agar assay). However, the S100P-overexpressing cell colonies showed a smaller colony size. This observation was supported by proliferation assays demonstrating a reduced proliferation per increasing cell density of the H358 cells overexpressing S100P. Migration of S100P-overexpressing H358 cells was diminished (transwell migration and in vitro wound scratch assays). Inhibiting DNA methylation with 5-aza-2'deoxycytidine enhanced the mRNA expression of S100P, whereas high S100P levels following overexpression suppressed the mRNA expression of endogenous S100P. In this regard, an upregulation of S100P in lung adenocarcinomas was only determined for early/T1 stage but not more advanced/T2 stage tumours compared with normal lung tissues. Thus, S100P induction may be considered an important step in the initial stage of lung adenocarcinomas, whereas its downregulation in advanced stages seems to be important for tumour progression in which DNA methylation and/or feedback transcription processes play a critical role.

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Abstract. The Ô-acyltransferase Porcupine contributes to secretion and function of Wnt signaling molecules, which stimulate the expression of various cancer-related genes. Porcupine is also involved in the Wnt-induced cell signaling via ß-Catenin in non-small cell lung carcinoma (NSCLC) cells. Herein, we report that the expression level of Porcupine in human NSCLC tissues (n=89) positively correlates with the expression of several genes coding for cancer-related molecules such as ß-Catenin, Hypoxia-inducible factor-1· and Jun B. However, the mRNA expression of Porcupine was not generally increased in NSCLC compared to normal lung tissues. In NSCLC tissues we also found a positive correlation between the expression level of Porcupine and the calcium-binding protein S100P, which contributes to initiation and invasion of cancer cells. Subsequent studies showed that the DNA hypomethylation with 5-aza-2'deoxycytidine increased the mRNA expression of S100P in NSCLC cells but did not alter that of Porcupine. Silencing the expression of Porcupine with small interfering (si)RNA reduced the expression of S100P in NSCLC cells, whereas silencing the expression of S100P with siRNA did not effect the level of Porcupine expression. In conclusion, besides DNA methylation processes, Porcupine might regulate the expression of some cancer-related molecules including S100P in human NSCLC.