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Cytochrome P450 2A13 (CYP2A13), mainly expressed in human respiratory tract, is highly efficient in the metabolic activation of aflatoxin (AF) B1 (AFB1) and is assumed to play a role in human lung tumorigenesis in airborne AFB1 exposure. To validate the assumption, we exposed human bronchial epithelial (BEAS-2B) cells stably expressing CYP2A13 (B-2A13), CYP1A2 (B-1A2) and CYP2A6 (B-2A6) to 0.1-10 nM AFB1 for 30-50 passages. B-2A13 cells showed increased sensitivity to 0.1 nM AFB1-induced neoplastic transformation and the formation of tumors in nude mice were observed at passage 30 (P30) while it occurred at P50 B-1A2 cells. B-2A6, similar to vector control, showed no neoplastic transformation in this condition. Additionally, AFB1-DNA adducts and 8-OHdG significantly increased in transformed P40 B-2A13, in parallel with the upregulation of p-ATR, p-BRCA1, Mre11, Rad50 and Rad51. However, the apoptosis of P40 cells was near normal, while the expression of Bax, C-Caspase 3 and C-PARP increased passage-dependently. Inhibition of ATR (ATR siRNA or NU6027) reversely increased the apoptosis of P40 B-2A13 cells in parallel with the upregulation of Bax, C-Caspase 3 and C-PARP, suggesting that ATR plays an important role in maintaining cell survival via antiapoptosis. Additionally, activation of ATR was necessary to neoplastic transformation since blockage of ATR in P40 cells inhibited DNA damage repair response and anchorage-independent growth. Our data demonstrated that CYP2A13 played a critical role in AFB1-induced neoplastic transformation. ATR-mediated the dysfunction of apoptosis and DNA damage repair might be involved. These results help establish a linkage between airborne AFB1 and human respiratory carcinoma.Aflatoxins (AFs) are primarily produced by the food-borne fungi Aspergillus flavus and Aspergillus parasiticus, which colonize a variety of food commodities, including maize, oilseeds, spices, groundnuts, and tree nuts. Currently, more than 55 million people worldwide suffer from uncontrolled exposure to AFs. 1 In China, corn is the food most seriously contaminated with AFs. 2 Aflatoxin B1 (AFB1) is the main AF found as a contaminant in foods, and high concentrations of AFB1 are commonly found in respirable, airborne dusts in amounts as high as 52 ppm. 3 Furthermore, predicted occupational exposure of AFB1 in a corn-processing plant was 107 ng/m 3 , and the daily exposure to AFB1 was calculated to be 40-856 ng. 4 Research in Denmark found that 7 of 45 animalfeed production plant workers had detectable levels of AFB1 in their blood after working for 4 weeks in the factory or unloading raw materials from ships. 5 AFB1 has been evaluated and classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans. Epidemiological surveys have revealed a strong statistical correlation between AF ingestion and incidence of hepatocellular carcinoma (HCC) in several areas of the world. 6 AFs may play a causative role in 4.6-28.2% of all global HCC cases. 7 Additionally, lung cancer has been a l...

Background: Breast Cancer (BC) is the leading cause of cancer-related deaths among women. As such, novel chemotherapeutic agents are urgently needed, especially for Triple-Negative Breast Cancer (TNBC). Hydroxytyrosol (HT) and Oleuropein (OL) are rich in olive oil, which is associated with a low occurrence of BC. However, the effects and mechanisms of action of HT and OL in BC cells are still unclear. This study aimed to explore the molecular mechanisms underlying the antitumor effect of HT and OL in TNBC. Methods: TNBC MDA-MB-231 cells were treated with HT and OL in combination with Hepatocyte Growth Factor (HGF), rapamycin (Rapa, an inducer of autophagy) or 3-methyladenine (3-MA, an inhibitor of autophagy). Cell viability, migration, invasion, and autophagy signaling were analyzed by scratch assays, transwell migration assays, and Western blot analysis. Results: Treatment with HT or OL reduced MDA-MB-231 cell viability in a dose-dependent manner. MDAMB- 231 cells were more sensitive to HT treatment than OL treatment. Rapa treatment could significantly block HGF-induced MDA-MB-231 cell migration and invasion, suggesting that inhibition of autophagy could promote migration and invasion. Moreover, HT or OL treatment significantly suppressed HGF or 3-MA induced cell migration and invasion by reversing LC3-II/LC3-I and Beclin-1 downregulation and reversing p62 upregulation. Conclusion: These data indicated that HT and OL may inhibit migration and invasion of TNBC cells by activating autophagy. These findings provide potential therapeutic strategies that target autophagy to limit the pathogenesis and progression of BC.

Cytochrome P450 2A13 (CYP2A13) is an extrahepatic enzyme that mainly expresses in human respiratory system, and it is reported to mediate the metabolic activation of aflatoxin B1. Due to the structural similarity, AFG1 is predicted to be metabolized by CYP2A13. However, the role of CYP2A13 in metabolic activation of AFG1 is unclear. In present study, human bronchial epithelial cells that stably express CYP2A13 (B-2A13) were used to conduct the effects of AFG1 on cytotoxicity, apoptosis, DNA damages, and their response protein expression. Low concentrations of AFG1 induced significant cytotoxicity and apoptosis, which was consistent with the increased expressions of pro-apoptotic proteins, such as C-PARP and C-caspase-3. In addition, AFG1 increased 8-OHdG and γH2AX in the nuclies and induced S phase arrest and DNA damage in B-2A13 cells, and the proteins related to DNA damage responses, such as ATM, ATR, Chk2, p53, BRCA1, and γH2AX, were activated. All the above effects were inhibited by nicotine (a substrate of CYP2A13) or 8-MOP (an inhibitor of CYP enzymes), confirming that CYP2A13 mediated the AFG1-induced cytotoxicity and DNA damages. Collectively, our findings first demonstrate that CYP2A13 might be an efficient enzyme in metabolic activation of AFG1 and helps provide a new insight into adverse effects of AFG1 in human respiratory system.

ObjectiveTo investigate the metabolites of polybrominated diphenyl ether 99 (BDE-99) and its related cytochrome P450s in an in vitro system.MethodsRat primary hepatocytes were isolated and treated with BDE-99 for 24-72 h. Metabolites were then extracted from the hepatocytes and media, and detected by GC/MS. Several mRNAs of metabolic enzymes were also extracted from the same cells and the gene expression levels were determined using quantitative real-time PCR. In addition, selected recombinant cytochrome P450s (CYPs) were expressed in a bacurovirus/sf9 system, and these were further used to explore the metabolism of BDE-99 in vitro. The parent depletion approach was used for screening the ability of CYPs to eliminate BDE-99.ResultsA reductively debrominated metabolite, BDE-47, and three oxidative metabolites, 2, 4, 5-tribromophenol, 5-OH-BDE-47, and 5′-OH-BDE-99, were identified from the BDE-99-treated rat hepatocytes, whereas no MeO metabolite was detected in the system. RT-PCR analysis showed that CYP 3A23/3A1, 1A2, and 2B1/2 were induced by BDE-99. Furthermore, using the heterological expressed CYP proteins in in vitro BDE-99 metabolism experiments we found that CYP1A2 and CYP3A4 showed the highest metabolic efficiency for BDE-99, with the metabolic clearance rates of CYP1A2 and CYP3A4 being 30.3% and 27.7%, respectively. CYP1A1 and CYP2A6 displayed relatively low clearance rates, while CYP2E1 seemed not to be associated with the BDE-99 metabolism.ConclusionsIn our in vitro rat primary hepatocyte metabolism system, four metabolites of BDE-99 were identified, and CYP3A4 and CYP1A2 were demonstrated to be involved in the BDE-99 metabolism.

In recent years shape-memory polymers have been under intense investigation due to their unique mechanical, thermal, and electrical properties that could potentially make them extremely valuable in numerous engineering applications. In this manuscript, we report a polymer-template-assisted assembly manufacturing strategy used to fabricate graphite/silver nanowires/epoxy resin (PGSE) composite. In the proposed method, the porous polymer foams work as the skeleton by forming three-dimensional graphite structure, whereas the silver nanowires act as the continuous conductive network. Preliminary testing on hybrid foams after vacuum infusion showed high electrical conductivity and excellent thermal stability. Furthermore, the composites were found to recover their original shape within 60 seconds from the application of a 0.8 V mm−1 electric field. Notably, the reported shape-memory polymer composites are manufactured with readily-available raw materials, they are fast to manufacture, and are shape-controlled.