RasGTPase-activating protein is a target of caspases in spontaneous apoptosis of lung carcinoma cells and in response to etoposide

p120 RasGTPase-activating protein (RasGAP), the main regulator of Ras GTPase family members, is cleaved at low caspase activity into an N-terminal fragment that triggers potent anti-apoptotic signals via activation of the Ras/PI-3 kinase/Akt pathway. When caspase activity is increased, RasGAP fragment N is further processed into two fragments that effectively potentiate apoptosis. Expression of RasGAP protein and its cleavage was assessed in human lung cancer cells with different histology and responsiveness to anticancer drug-induced apoptosis. Here we show that therapy-sensitive small lung carcinoma cell (SCLC) lines have lower RasGAP expression levels and higher spontaneous cleavage with formation of fragment N compared to therapy-resistant non-small cell lung carcinoma cell (NSCLC) lines. The first RasGAP cleavage event strongly correlated with the increased level of spontaneous apoptosis in SCLC. However, generation of protective RasGAP fragment N also related to the potency of SCLC to develop secondary therapy-resistance. In response to etoposide (ET), RasGAP fragment N was further cleaved in direct dependence on caspase-3 activity, which was more pronounced in NSCLC cells. Caspase inhibition, while effectively preventing the second cleavage of RasGAP, barely affected the first cleavage of RasGAP into fragment N that was always detectable in NSCLC and SCLC cells. These findings suggest that different levels of RasGAP and fragment N might play a significant role in the biology and different clinical course of both subtypes of lung neoplasms. Furthermore, constitutive formation of RasGAP fragment N can potentially contribute to primary resistance of NSCLC to anticancer therapy by ET but also to secondary therapy-resistance in SCL

Reduced proliferation capacity of lung cells in chronic obstructive pulmonary disease

Background and objectivesThe prevalence of chronic obstructive pulmonary disease (COPD) and lung emphysema increases with age and both lung diseases are again risk factors for lung cancer. Since areduced capacity of fibroblasts for proliferation is agood indicator of tissue aging, we studied the cell proliferation of lung fibroblasts from normal and tumor tissue of lung cancer patients depending on lung comorbidities.Material and methodsFibroblasts were isolated from tumor and normal lung tissue of 40lung cancer patients. Cumulative population doubling (CPD) was determined to assess the proliferation capacity, and the PCR technique was used to measure telomere lengths. Since many patients had previously been exposed to severe air pollution, we also studied the effect of air pollution particles on the fibroblast CPD in vitro.ResultsFibroblasts from tumor and normal lung tissue had comparable CPDs; however, the CPD of fibroblasts from both tumor and normal lung tissue was significantly reduced in patients also suffering from COPD. This CPD reduction was highest in COPD patients who had already developed emphysema or were smokers. Asignificant correlation between CPD and telomere length was identified only for fibroblasts of non-COPD patients. Further studies also showed an adverse effect of air pollution particles on the CPD of lung fibroblasts.ConclusionLung cells of COPD patients are characterized by accelerated senescence which must have been initiated prior to lung tumorigenesis and cannot depend on telomere shortening only. In addition to smoking as aknown risk factor for COPD and lung cancer, air pollution particles could be another reason for the accelerated senescence of lung cells

Microarray-Based Gene Expression Profiling Suggests adaptation of Lung Epithelial Cells Subjected to Chronic Cyclic Strain

Background/Aims: Mechanical strain of the lung tissue is a physiological process that affects the behavior of lung cells. Since recent evidence also suggests alterations in the expression of certain genes as a consequence of mechanotransduction, our study aimed at the analysis of the gene expression profile in lung epithelial cells subjected to chronic cyclic strain. Methods: Various human lung epithelial cell lines (A549 as principal adherent cell line and four others) were subjected to cyclic strain (16 % surface distension, 12 min-1) in a Strain Cell Culture Device for 24 h. In comparison to static controls, expression analyses were performed by gene microarray and qPCR. Results: Microarray analysis revealed many differences in the gene expression but at moderate levels. Altogether 25 genes were moderately down-regulated (0.86-fold ± 0.06) and 26 genes were up-regulated (1.18-fold ± 0.10) in A549 and the others. Strain-regulated genes often code for transcription factors, such as E2F4 and SRF. qPCR analyses confirmed the up-regulation of both transcription factors and further genes, such as PLAU (urokinase-type plasminogen activator) and S100A4 (S100 protein A4). Moreover, we showed the down-regulations of AGR2 (anterior gradient 2) and LCN2 (lipocalin 2). Conclusions: We identified many genes of which the expression was moderately altered in lung epithelial cells subjected to chronic cyclic strain. Although many moderate changes in the gene expression profile might affect cellular behavior, it also suggests an effective adaptation of cells to mechanical forces in long-term conditions

Diabetes prevalence and outcomes in hospitalized cardiorenal-syndrome patients with and without hyponatremia

Background!#!Hyponatremia is known to be associated with a worse patient outcome in heart failure. In cardiorenal syndrome (CRS), the prognostic role of concomitant hyponatremia is unclear. We sought to evaluate potential risk factors for hyponatremia in patients with CRS presenting with or without hyponatremia on hospital admission.!##!Methods!#!In a retrospective study, we investigated 262 CRS patients without sepsis admitted to the University Hospital Halle over a course of 4 years. CRS diagnosis was derived from an electronic search of concomitant diagnoses of acute or chronic (NYHA 3-4) heart failure and acute kidney injury (AKIN 1-3) or chronic kidney disease (KDIGO G3-G5!##!Results!#!Two hundred sixty-two CRS patients were included in this study, thereof, 90 CRS patients (34.4%) with hyponatremia (Na < 135 mmol/L). The diabetes prevalence among CRS patients was high (> 65%) and not related to the serum sodium concentration on admission. In comparison to non-hyponatremic CRS patients, the hyponatremic patients had a lower serum osmolality, hypovolemia was more prevalent (41.1% versus 16.3%, p < 0.001). As possible causes of hypovolemia, diarrhea, a higher number of diuretic drug classes and higher diuretic dosages were found. Hyponatremic and non-hyponatremic CRS patients had a comparable need for renal-replacement therapy (36.7% versus 31.4%) during the hospital stay. However, after discharge, relatively more hyponatremic CRS patients on renal replacement therapy switched to a non-dialysis therapy regimen (50.0% versus 22.2%). Hyponatremic CRS patients showed a trend for a higher in-hospital mortality (15.6% versus 7.6%, p = 0.054), but no difference in the one-year mortality (43.3% versus 40.1%, p = 0.692).!##!Conclusions!#!All CRS patients showed a high prevalence of diabetes mellitus and a high one-year mortality. In comparison to non-hyponatremic CRS patients, hyponatremic ones were more likely to have hypovolemia, and had a higher likelihood for temporary renal replacement therapy