ABSTRACT
Benzo[a]pyrene (B[a]P), the most extensively studied carcinogen in cigarette smoke, has been regarded as a critical mediator of lung cancer. It is known that B[a]P-mediated Aryl hydrocarbon Receptor (AhR) activation stimulates the mitogen activated protein kinases (MAPK) signaling cascade in different cell models. MAPK pathway disturbances drive alterations in cellular processes, such as differentiation, proliferation, and apoptosis, and the disturbances may also modify the AhR pathway itself. However, MAPK involvement in B[a]P metabolic activation and toxicity in lung tissues is not well understood. Here, we used a non-transformed human bronchial epithelial lung cell line, BEAS-2B, to study the participation of ERK 1/2 kinases in the metabolic activation of B[a]P and in its related genotoxic effects. Our results indicate that B[a]P is not cytotoxic to BEAS-2B cells at relatively low concentrations, but it enhances CYP1A1 gene transcription and protein induction. Additionally, B[a]P promotes Src and ERK 1/2 phosphorylation. Accordingly, inhibition of both Src and ERK 1/2 phosphorylation decreases CYP1A1 protein induction, AhR nuclear translocation and production of B[a]P adducts. Together, these data suggest a crosstalk between AhR and the members of the MAPK pathway, ERK 1/2 mediated by Src kinase. This interaction is important for the adequate AhR pathway signaling that in turn induces transcription and protein induction of CYP1A1 and B[a]P-induced DNA damage in BEAS-2B cells.
Subject(s)
Basic Helix-Loop-Helix Transcription Factors/agonists , Benzo(a)pyrene/toxicity , Carcinogens, Environmental/toxicity , Cytochrome P-450 CYP1A1/metabolism , MAP Kinase Signaling System/drug effects , Proto-Oncogene Proteins pp60(c-src)/metabolism , Receptors, Aryl Hydrocarbon/agonists , Respiratory Mucosa/drug effects , Active Transport, Cell Nucleus/drug effects , Basic Helix-Loop-Helix Transcription Factors/metabolism , Bronchi/drug effects , Bronchi/metabolism , Cell Line , Cell Survival/drug effects , Cytochrome P-450 CYP1A1/chemistry , Cytochrome P-450 CYP1A1/genetics , DNA Adducts/chemistry , DNA Adducts/drug effects , Enzyme Activation/drug effects , Enzyme Induction/drug effects , Humans , Hydrophobic and Hydrophilic Interactions , Kinetics , Phosphorylation/drug effects , Protein Kinase Inhibitors/pharmacology , Protein Processing, Post-Translational/drug effects , Proto-Oncogene Proteins pp60(c-src)/chemistry , Receptors, Aryl Hydrocarbon/metabolism , Respiratory Mucosa/metabolismABSTRACT
Rhipicephalus microplus is the most economically important cattle tick in the Mexican tropics. Wild ungulate species, including red deer (Cervus elaphus), are gaining popularity in diversified livestock ranching operations in Mexico. However, there is no information available on the susceptibility of red deer to infestation with the cattle tick, R. microplus, under hot, subhumid tropical conditions in Mexico. Biological data on R. microplus as an ectoparasite of cattle and red deer in a farm in the Mexican tropics are presented here. Ticks collected from red deer were identified as R. microplus (97 %) and Amblyomma cajennense (3 %), and tick species infesting cattle included R. microplus (95 %) and A. cajennense (5 %). Standard counts of R. microplus engorged females on red deer were 11 times higher than on cattle (428 ± 43 vs. 40 ± 18; p < 0.001). The reproductive efficiency index and larval hatching of R. microplus collected from cattle and red deer were similar (p > 0.05). Hemolymph samples of R. microplus collected from cattle were positive for Babesia spp. (10 %, 2/50) and all the samples from ticks infesting red deer were negative. Seventeen and ten percent of the blood samples from cattle and red deer were positive for Anaplasma marginale, respectively. The role of red deer as a host of R. microplus in Yucatan, Mexico and the importance of this host-parasite relationship relative to the epidemiology of R. microplus-borne diseases are discussed.
Subject(s)
Arachnid Vectors/physiology , Deer/parasitology , Host-Parasite Interactions , Rhipicephalus/physiology , Anaplasma marginale/isolation & purification , Animals , Babesia/isolation & purification , Cattle , Cattle Diseases/parasitology , Cattle Diseases/prevention & control , Cattle Diseases/transmission , Female , Mexico , Rhipicephalus/parasitology , Tick Infestations/epidemiologyABSTRACT
Constitutive overexpression of Cyp6g1 and Cyp6a2 genes in DDT-resistant line Oregon-flare of the Drosophila melanogaster wing spot test (SMART) has been reported. Cyp6g1 and Cyp6a2 expression levels were compared against the ß-actin gene in the standard (ST) and high bioactivation (HB) crosses of the Somatic Mutation and Recombination test (SMART) treated with sulforaphane or phenobarbital as the control inductor. The CYP450s' enzymatic activity was determined by overall NADH consumption. The expression levels of both genes and the CYP450s activity was higher in the HB cross. The Cyp6g1 levels were higher than those of Cyp6a2 in both crosses, but lower than the expression of ß-actin. Sulforaphane decreased Cyp6g1 in the HB cross and increased it in the ST cross; Cyp6a2 expression was inhibited in the ST cross. Sulforaphane resulted mutagenic in the ST cross, which could be related to the inhibition of Cyp6a2. Phenobarbital did not modify the Cyp6g1 levels but increased the Cyp6a2 and CYP450s basal activity. Although the transcript levels were always higher in the HB cross than in the ST, the expression of Cyp6a2 and Cyp6g1 was not constitutive and was independent one from the other. Sulforaphane modulated both genes in a differential way in each cross and, in contrast to its putative protective effect, it resulted to be mutagenic.
