Ras p21 protein levels in human plasma from patients with chronic obstructive pulmonary disease (COPD) compared with lung cancer patients and healthy controls

A comparative protein analysis of lung cancer, along with three controls using a multidimensional proteomic approach

IMPACT STATEMENT

A multistep proteomics fractionation strategy was developed and validated for the discovery of proteomic biomarkers which could be used as potential diagnostic biomarkers for monitoring the progression of disease in smokers and COPD patients towards lung cancer.

Zinc oxide nanoparticles affect the expression of p53, Ras p21 and JNKs: an ex vivo/in vitro exposure study in respiratory disease patients

Zinc oxide (ZnO) nanoparticles are the mostly used engineered metal oxide nanoparticles in consumer products. This has increased the likelihood of human exposure to this engineered nanoparticle (ENPs) through different routes. At present, the majority of the studies concerning ZnO ENPs toxicity have been conducted using in vitro and in vivo systems. In this study, for the first time we assessed the effect of ZnO ENPs on the major cellular pathways in the lymphocytes of healthy individuals as well as in susceptible patients suffering from lung cancer, chronic obstructive pulmonary disease (COPD) and asthma. Using the differential expression analysis, we observed a significant (P < 0.05) dose-dependent (10, 20 and 40 µg/ml for 6h) increase in the expression of tumour suppressor protein p53 (40, 60 and 110%); Ras p21 (30, 52 and 80%); c-Jun N-terminal kinases; JNKs) (28, 47 and 78%) in lung cancer patient samples treated with ZnO ENPs compared to healthy controls. A similar trend was also seen in COPD patient samples where a significant (P < 0.05) dose-dependent increase in the expression of tumour suppressor protein p53 (26, 45 and 84%), Ras p21 (21, 40 and 77%), JNKs (17, 32 and 69%) was observed after 6h of ZnO ENPs treatment at the aforesaid concentrations. However, the increase in the expression profile of tested protein was not significant in the asthma patients as compared to controls. Our results reiterate the concern about the safety of ZnO ENPs in consumer products and suggest the need for a complete risk assessment of any new ENPs before its use.

Differential expression analysis for pathways

Life science technologies generate a deluge of data that hold the keys to unlocking the secrets of important biological functions and disease mechanisms. We present DEAP, Differential Expression Analysis for Pathways, which capitalizes on information about biological pathways to identify important regulatory patterns from differential expression data. DEAP makes significant improvements over existing approaches by including information about pathway structure and discovering the most differentially expressed portion of the pathway. On simulated data, DEAP significantly outperformed traditional methods: with high differential expression, DEAP increased power by two orders of magnitude; with very low differential expression, DEAP doubled the power. DEAP performance was illustrated on two different gene and protein expression studies. DEAP discovered fourteen important pathways related to chronic obstructive pulmonary disease and interferon treatment that existing approaches omitted. On the interferon study, DEAP guided focus towards a four protein path within the 26 protein Notch signalling pathway.

The data deluge represents a growing challenge for life sciences. Within this sea of data surely lie many secrets to understanding important biological and medical systems. To quantify important patterns in this data, we present DEAP (Differential Expression Analysis for Pathways). DEAP amalgamates information about biological pathway structure and differential expression to identify important patterns of regulation. On both simulated and biological data, we show that DEAP is able to identify key mechanisms while making significant improvements over existing methodologies. For example, on the interferon study, DEAP uniquely identified both the interferon gamma signalling pathway and the JAK STAT signalling pathway.

Receptor for advanced glycation end-products signals through Ras during tobacco smoke-induced pulmonary inflammation

We previously demonstrated up-regulation of the receptor for advanced glycation end-products (RAGE) and its ligands by cigarette smoke extract (CSE) in rat R3/1 cells, a type I-like alveolar epithelial cell line. However, RAGE-mediated intracellular signaling pathways that lead to pulmonary inflammation remained unclear. Using ELISAs, we demonstrate that alveolar epithelial cell lines exposed to 25% CSE for 2 hours induce the activation of Ras, a small GTPase that functions as a molecular switch in the control of several intracellular signaling networks. Conversely, cells treated with siRNA for RAGE (siRAGE) resulted in decreased Ras activation. Furthermore, Ras was significantly diminished in lungs from RAGE null mice exposed to chronic tobacco smoke when compared with smoke-exposed wild-type mice. The use of a luciferase reporter containing NF-κB binding sites also demonstrated elevated NF-κB activation in R3/1 cells after CSE stimulation and decreased NF-κB activation in cells transfected with siRAGE before CSE exposure. ELISA revealed an increase in the secretion of IL-1β and CCL5 by R3/1 cells, two cytokines induced by NF-κB and associated with leukocyte chemotaxis. Furthermore, real-time RT-PCR and ELISAs revealed decreased cytokine secretion in RAGE null mouse lung exposed to tobacco smoke compared with lungs from smoke-exposed wild-type animals. These results support the conclusion that CSE-induced RAGE expression functions in pathways that involve Ras-mediated NF-κB activation and cytokine elaboration. This RAGE-Ras-NF-κB axis likely contributes to inflammation associated with several smoking-related inflammatory lung diseases.

Systematic review with meta-analysis of the epidemiological evidence relating smoking to COPD, chronic bronchitis and emphysema

BACKGROUND

Smoking is a known cause of the outcomes COPD, chronic bronchitis (CB) and emphysema, but no previous systematic review exists. We summarize evidence for various smoking indices.

METHODS

Based on MEDLINE searches and other sources we obtained papers published to 2006 describing epidemiological studies relating incidence or prevalence of these outcomes to smoking. Studies in children or adolescents, or in populations at high respiratory disease risk or with co-existing diseases were excluded. Study-specific data were extracted on design, exposures and outcomes considered, and confounder adjustment. For each outcome RRs/ORs and 95% CIs were extracted for ever, current and ex smoking and various dose response indices, and meta-analyses and meta-regressions conducted to determine how relationships were modified by various study and RR characteristics.

RESULTS

Of 218 studies identified, 133 provide data for COPD, 101 for CB and 28 for emphysema. RR estimates are markedly heterogeneous. Based on random-effects meta-analyses of most-adjusted RR/ORs, estimates are elevated for ever smoking (COPD 2.89, CI 2.63-3.17, n = 129 RRs; CB 2.69, 2.50-2.90, n = 114; emphysema 4.51, 3.38-6.02, n = 28), current smoking (COPD 3.51, 3.08-3.99; CB 3.41, 3.13-3.72; emphysema 4.87, 2.83-8.41) and ex smoking (COPD 2.35, 2.11-2.63; CB 1.63, 1.50-1.78; emphysema 3.52, 2.51-4.94). For COPD, RRs are higher for males, for studies conducted in North America, for cigarette smoking rather than any product smoking, and where the unexposed base is never smoking any product, and are markedly lower when asthma is included in the COPD definition. Variations by sex, continent, smoking product and unexposed group are in the same direction for CB, but less clearly demonstrated. For all outcomes RRs are higher when based on mortality, and for COPD are markedly lower when based on lung function. For all outcomes, risk increases with amount smoked and pack-years. Limited data show risk decreases with increasing starting age for COPD and CB and with increasing quitting duration for COPD. No clear relationship is seen with duration of smoking.

CONCLUSIONS

The results confirm and quantify the causal relationships with smoking.

Oncogene and tumor-suppressor gene products as serum biomarkers in occupational-derived lung cancer

Since lung cancer is the most frequent occupational cancer and one of the leading causes of cancer mortality in the world, it is one of the biggest challenges for research. In the literature, there are inconsistent results regarding the utility of the serum biomarkers p53, anti-p53 antibodies, EGF receptor or Ras. Based on the published results, routine use of these biomarkers for detection of occupationally derived lung carcinomas is not currently recommended. In this review, we summarize the literature and discuss the relevance of these oncogene and tumor-suppressor gene products as serum biomarkers in occupational-derived lung cancer.

Expression of ras (p21) protein in plasma from exposed workers and from patients with lung disease

Oncogenes are involved with the regulation of cellular proliferation and thus could be important in the development of many cancers. Cells transformed in culture by ras genes can be activated either by the introduction of specific point mutations or by overexpression of the normal proto-oncogene. The ras genes encode a protein of 189 amino acids (molecular mass 21 kDa) designated as p21. ras p21 proteins are contained in all eukaryotic cells on the inner surface of the plasma membrane. We measured ras p21 proteins in lung cancer patients, patients with chronic obstructive pulmonary disease (COPD) and workers exposed to emissions from petrochemical plants and 1,3-butadiene and 1,3-butadiene/styrene. Proteins were separated by gel electrophoresis, transferred to a nitrocellulose membrane by Western blotting and detected by chemiluminescence. A monoclonal pan-ras antibody was used as the primary antibody. Optical densities of the peak area of the protein bands were calculated and values which were two standard deviations above negative control means were considered positive. Many of the cancer patients and some of the COPD patients gave positive responses, whilst exposed worker groups did not show statistically significant increases by comparison with the controls. Thus, an increase in ras oncoproteins could be a biomarker for cancer or the disease state in general, but it cannot be ruled out that it is a biomarker for exposure since many of the individuals examined were smokers exposed to cigarette smoke.

Serum ras (p21) as a marker for occupationally derived lung cancer?

Certain subsets of the population are especially sensitive to carcinogens, and this can be determined using molecular biological methods. In the literature there has been evidence presented for the use of p21ras (ras) as a tumor marker for human carcinogenic substances such as asbestos, polycyclic aromatic hydrocarbons, and vinyl chloride in the workplace. In this study we have examined whether serum ras could serve as a biomarker for the early detection of occupationally derived lung cancer, with an emphasis on Schneeberger (radon-induced) lung cancer. Sera were taken from 65 male tumor patients. Fifty-nine patients suffered from primary lung cancer (including 18 patients with Schneeberger lung cancer and 12 patients with asbestos-related lung cancer). Additionally, 29 patients with non-malignant lung disease, and a healthy control group (44) including 32 former uranium miners of SDAG Wismut exposed to ionizing radiation (radon and its decay products) were examined. Ras protein was determined via three different methods: 1) immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting; 2) SDS-PAGE using 5-17% gradient gels followed by Western blotting; 3) pre-incubation with Blue Sepharose, SDS-PAGE on 5-17% gradient gels, and Western blotting. The results show that 1 ng ras protein was measurable in serum standards. This protein could not be detected in patient sera or in sera from any of the study groups. Thus, ras cannot be considered useful as a marker for the early detection of asbestos-induced or Schneeberger lung cancer.