Estrogen promotes benzo[a]pyrene-induced lung carcinogenesis through oxidative stress damage and cytochrome c-mediated caspase-3 activation pathways in female mice

Fullerene C60 reduces acute lung injury by suppressing oxidative stress-mediated DMBA-induced apoptosis and autophagy by regulation of cytochrome-C/caspase-3/beclin-1/IL-1α/HO-1/p53 signaling pathways in rats

The objective of this study was to evaluate the effect of fullerene C60 nanoparticles against 7,12-dimethylbenz[a]anthracene (DMBA)-induced lung tissue damage in rats. 60 Wistar albino (8 weeks old) female rats were assigned into four groups: Control Group (C), Fullerene C60, DMBA, and Fullerene C60+DMBA. The rats in the DMBA and Fullerene C60+DMBA groups were administered DMBA (45 mg/kg bw, oral gavage). The rats in Fullerene C60, and Fullerene C60+DMBA groups were administered with Fullerene C60 (1.7 mg/kg bw, oral gavage). Expression levels of cytochrome-C, caspase-3, beclin-1, IL-1α, HO-1 and p53 proteins in lung tissue were determined by western blotting, lipid peroxidation malondialdehyde (MDA) analyzes, glutathione (GSH), glutathione peroxidase (GSH-Px), catalase activity (CAT) and total protein levels were determined by spectrophotometer. In addition, lung tissues were evaluated by histopathologically. Fullerene C60 reduced the increasing of MDA and IL-1α protein expression levels and attenuated histopathological changes in lung. Moreover, fullerene C60 enhanced the protein expression of cytochrome-C, caspase-3, beclin-1, HO-1, and p53, which were decreased in the DMBA group. Fullerene C60 has strong biological activity that it might be an effective approach for lung damage.

The role of estrogen receptor β in fine particulate matter (PM2.5) organic extract-induced pulmonary inflammation in female and male mice

Fine particulate matter organic extract (Po) was reported to promote inflammation in the lung. Sex differences were reported in many inflammatory diseases. In this study, we investigated the effects of Po exposure on pulmonary inflammatory response and evaluated the role of sex in this process. While mice were exposed to 100 µg/m³ Po for 12 weeks by an inhalation exposure system, the lung histopathological analysis shown obvious inflammation, the cell numbers in bronchoalveolar lavage fluid (BALF) were significantly increased, and most inflammatory cytokines in BALF were upregulated. The results of factorial analysis of variance shown that there was an interaction between sex and Po exposure in the inflammatory cell numbers and the levels of tumor necrosis factor-α (TNF-α), interleukin-5 (IL-5), and growth-related oncogene/keratinocyte chemoattractant (GRO/KC). Notably, these changes and interactions were diminished while Po-exposed mice were administered with the estrogen receptor β (ERβ) antagonist. We speculated that sex might affect the levels of inflammatory indicators in BALF of Po-exposed mice and female mice were more prone to inflammation while exposed to Po. Moreover, ERβ was involved in these processes. To our knowledge, this is the first investigation about the role of sex in Po-induced adverse effects.

The smoking estrogens - a potential synergy between estradiol and benzo(a)pyrene

According to recent statistics, Lung Cancer (LC) is one of the most frequently diagnosed tumor types, representing nearly 12% of all global cancer cases. Moreover, in recent years, an increased mortality rate and incidence of this cancer were observed, especially among nonsmokers. Lung cancer patients are often characterized by poor prognosis and low survival rates, which encourages the scientific community to investigate the biochemical and molecular processes leading to the development of this malignancy. Furthermore, the mechanisms of LC formation and progression are not yet fully elucidated due to their high complexity, as well as a multitude of environmental, genetic, and molecular factors involved. Even though LC's association with exposure to cigarette smoke is indisputable, current research provides evidence that the development of this cancer can also be affected by the presence of estrogens and their interaction with several tobacco smoke components. Hence, the main goal of this brief review was to investigate reports of a possible synergy between 17β estradiol (E2), the most biologically active estrogen, and benzo(a)pyrene (BaP), a strongly carcinogenic compound produced as a result of incomplete tobacco combustion. The literature sources demonstrate a possible carcinogenic synergy between estrogens, especially E2, and BaP, a toxic tobacco smoke component. Therefeore, the combined effect of disturbed estrogen production in cancer cells, as well as the molecular influence exerted by BaP, could explain the increased aggressiveness and rate of LC development. Summarizing, the synergistic effect of these risk factors is an interesting area of further research.

Immuno-hormonal network in postmenopausal women: disturbance in breast cancer patients

Introduction

Antibodies to estradiol and progesterone (Es and Pg) modulated their blood serum concentration and biological effects in immunized animals. Antibodies to membrane steroid receptors acted as hormone agonists or antagonists in cell cultures.

Material and methods

Here we studied the levels of Es and Pg, idiotypic immunoglobulin (Ig) A1 and anti-idiotypic IgG2 specific to Es and Pg in the serum of postmenopausal women (82 healthy donors and 443 breast cancer patients).

Results

It was found that individual high ratios of Pg/Es (> 4), IgA-Pg1/IgA-Es1 (> 1) and IgG-Pg2/IgG-Es2 (> 1) were associated with low breast cancer risk (OR = 0.4-0.5). High ratios of IgA-Pg1/IgA-Es1 and IgG-Pg2/IgG-Es2 were associated with a high Pg/Es ratio in healthy women but not in breast cancer patients. The levels of idiotypic IgA to benzo[a]pyrene correlated significantly with IgA-Es1 and IgA-Pg1 levels in both compared groups. IgA-Pg1/IgA-Es1 ratio correlated with IgG-Pg2/IgG-Es2 only in healthy women but not in breast cancer patients.

Conclusions

The normal immune-hormonal balance supports the real adaptation of the organism to environmental carcinogens and inhibits the initiation and promotion of carcinogenesis. The disturbance between certain elements of this network (immune-hormonal disbalance) could stimulate carcinogenesis. Further studies of immune-hormonal interaction could be helpful for understanding the pathogenesis of other carcinogen-induced steroid-dependent diseases in humans.

PM2.5 organic extract mediates inflammation through the ERβ pathway to contribute to lung carcinogenesis in vitro and vivo

An increasing number of researches have shown that fine particulate matter (PM2.5) is closely related to increased respiratory inflammation and can even lead to lung cancer. Estrogen receptor β (ERβ) has been demonstrated to be involved in several cancers. However, the exact role of ERβ in PM2.5 organic extract (Po)-promoted inflammation and lung cancer remains unknown. The purpose of this study was to investigate whether ERβ is involved in Po induced inflammation and lung cancer. In vitro, our results showed that interleukin-6 (IL-6) and ERβ were simultaneously increased in lung bronchial epithelial cells exposed to Po; additionally, inhibition of ERβ decreased IL-6 expression and secretion through inactivating ERK and AKT and further promoted cells malignant transformation. Moreover, we performed an animal model of inhalation exposure to Po using female C57BL/6 mice. Although we were unable to find tumor tissue in mice exposed to Po, we detected evidence of lung inflammation, epithelial-to-mesenchymal transition (EMT) phenotype and severe pulmonary injury; in addition, intraperitoneal injection of PHTPP (an ERβ inhibitor) showed that the above phenomena have been improved, which demonstrate that Po stimulates IL-6 expression to promote inflammation, EMT phenotype and lung injury through the ERβ pathway. In conclusion, our results confirmed the potential toxic effect of PM2.5, and increased our understanding of PM2.5 carcinogenic potential by exploring the mechanism of ERβ regulating inflammation.

Protective effect of hawthorn extract against genotoxicity induced by benzo(<alpha>)pyrene in C57BL/6 mice

Benzo(<alpha>)pyrene [B(<alpha>)P], widely originated from environmental pollution or food process such as roasting and frying, is a strong mutagen and potent carcinogen. Utilization of hawthorn has been reported against physical mutagens. Our study found that hawthorn extract (HE) contained abundant phenolic compounds, wherein chlorogenic acid was 2.78 mg/g, procyanidine B2 was 3.58 mg/g, epicatechin was 2.99 mg/g DW, which may contribute to anti-genotoxicity activity. So, the role of HE against B(<alpha>)P-induced genotoxicity in C57BL/6 mice was further assessed. Fifty mice were distributed into five groups: control group, B(<alpha>)P group (30 mg/kg, i.p.), B(<alpha>)P + HE-L group (100 mg/kg, i.g.), B(<alpha>)P + HE-M group (200 mg/kg, i.g.), B(<alpha>)P + HE-H group (400 mg/kg, i.g.). Mice were orally administered with solutions of HE for 10 days and injected intraperitoneally with B(<alpha>)P for 3 days from the 8th day. Results showed that B(<alpha>)P can induce significantly pathological damage in liver, lung and spleen, as well as decrease white blood cells (WBCs). Remarkably elevated levels of reactive oxygen species (ROS), DNA strand breaks (DSBs) and G1 cell cycle arrest were also found in B(<alpha>)P group, with upregulated expressions of p-H2AX, p-p53 and p21 in bone marrow cells. With administration of HE, liver, lung and spleen injury significantly mitigated, while WBCs were evidently increased in B(<alpha>)P-treated mice. Consistently, HE markedly reduced level of ROS, DSBs and G1 cell cycle arrest accompanied by reducing expressions of p-H2AX, p-p53 and p21 in bone marrow cells. Combined, these results indicated a protective role of HE on B(<alpha>)P-induced genotoxicity.

Immunomodulation of carcinogens-induced steroids-dependent human diseases

The experimental and clinical data about antibodies against environmental chemical carcinogens and endogenous steroids are represented. The conception of immunomodulation of carcinogens- and steroids-dependent human diseases is proposed. It is postulated that antibodies to polycyclic aromatic hydrocarbons and heterocyclic amines in cooperation with antibodies to cholesterol, sex hormones, mineralo- and glucocorticoids stimulate or inhibit cancer, malformation, cardiovascular and autoimmune diseases depending on their personal combination. It is recommended to use immunoassay of these antibodies for the human diseases prediction. The alternative approaches for prevention using the probiotics transformed by anti-carcinogen antibodies are substantiated.

Immunization against environmental chemical carcinogens: Pro and contra

The problems of immunoprotection from the environmental chemical carcinogens are discussed. The main experimental argument pro active immunization against carcinogens is a possibility of specific mucosal antibodies (Abs) to inhibit the penetration of carcinogens from environment and to stimulate its excretion with the following decreasing of carcinogen-DNA adducts levels. Hypothesis of cancer immunostimulation after active immunization against carcinogens is based on a high cancer risk in persons with high levels of serum Abs specific to environmental carcinogens coupled with high levels of Abs to endogenous steroids stimulating the proliferation of target cells, for example, Abs to benzo[a]pyrene together with Abs to estradiol. The active immunization could increase the cancer risk much more in those persons. The passive immunization could be an alternative safe approach to avoid this problem.

Sex-specific microRNA expression networks in an acute mouse model of ozone-induced lung inflammation

BACKGROUND

Sex differences in the incidence and prognosis of respiratory diseases have been reported. Studies have shown that women are at increased risk of adverse health outcomes from air pollution than men, but sex-specific immune gene expression patterns and regulatory networks have not been well studied in the lung. MicroRNAs (miRNAs) are environmentally sensitive posttranscriptional regulators of gene expression that may mediate the damaging effects of inhaled pollutants in the lung, by altering the expression of innate immunity molecules.

METHODS

Male and female mice of the C57BL/6 background were exposed to 2 ppm of ozone or filtered air (control) for 3 h. Female mice were also exposed at different stages of the estrous cycle. Following exposure, lungs were harvested and total RNA was extracted. We used PCR arrays to study sex differences in the expression of 84 miRNAs predicted to target inflammatory and immune genes.

RESULTS

We identified differentially expressed miRNA signatures in the lungs of male vs. female exposed to ozone. In silico pathway analyses identified sex-specific biological networks affected by exposure to ozone that ranged from direct predicted gene targeting to complex interactions with multiple intermediates. We also identified differences in miRNA expression and predicted regulatory networks in females exposed to ozone at different estrous cycle stages.

CONCLUSION

Our results indicate that both sex and hormonal status can influence lung miRNA expression in response to ozone exposure, indicating that sex-specific miRNA regulation of inflammatory gene expression could mediate differential pollution-induced health outcomes in men and women.

Decreased expression of cytochrome p450 1B1 in non-small cell lung cancer

Recent studies have associated oestrogen metabolism and cigarette smoking with their carcinogenic impact on the lungs. Compounds commonly found in tobacco smoke induce the activity of CYP1B1, the enzyme responsible for the synthesis of catecholic derivatives of oestrogens. During their redox transformations, these structures can release large amounts of reactive oxygen species or can form DNA adducts, which lead to the decomposition of genetic material. This process may illustrate the synergistic effect of oestrogenic activity and tobacco combustion on oestrogen-dependant lung cancer development. There is considerable evidence suggesting that the level of oestrogen in lung tumours is elevated. Therefore, by using reverse transcription, real-time PCR and Western Blot analysis, we evaluated the CYP1B1 status in tissues from 76 patients diagnosed with non-small cell lung cancer (NSCLC) to confirm whether potential overexpression of CYP1B1 may impact lung cancerogenesis induced by oestrogens. We found significantly lower levels of CYP1B1 transcripts (p=0.00001) and proteins (p=0.000085) in lung tumour material compared to corresponding, histopathologically unchanged tissues. We also analysed the association of CYP1B1 expression with gender, age and clinicopathological data of NSCLC patients. We observed lower amounts of CYP1B1 occurring in the middle stages of LC, regardless of gender, age or histological type of lung cancer.

Risk factors of Lung Cancer in nonsmoker

Generally, the cause of lung cancer is attributed to tobacco smoking. But many of the new lung cancer cases have been reported in nonsmokers. Apart from smoking; air pollution, environmental exposure, mutations, and single-nucleotide polymorphisms are known to be associated with lung cancer. Improper diet, alcohol consumption, marijuana smoking, estrogen, infections with human papillomavirus (HPV), HIV, and Epstein-Barr virus are suggested to be linked with lung cancer but clear evidences to ascertain their relation is not available. This article provides a comprehensive review of various risk factors and the underlying molecular mechanisms responsible for increasing the incidence of lung cancer. The pathologic, histologic, and genetic differences exist with lung cancer among smokers and nonsmokers. A better understanding of the risk factors, differences in pathology and molecular features of lung cancer in smokers and nonsmokers and the mode of action of various carcinogens will facilitate the prevention and management of lung cancer.

Exploring estrogenic activity in lung cancer

It is well known that a connection between xenobiotics inhalation, especially tobacco combustion and Lung Cancer development is strongly significant and indisputable. However, recent studies provide evidence indicating that another factors such as, estrogens are also involved in lung carcinoma biology and metabolism. Although the status of estrogen receptors (ER), in both cancerous and healthy lung tissue has been well documented, there is still inconclusive data with respect of which isoform of the receptor is present in the lungs. However according to several studies, ERβ appears to be predominant form. Apart from ERs, estrogens can work through a recently discovered G-coupled estrogen receptor. Binding with both types of the receptors causes a signal, which leads to i.e. enhanced cell proliferation. There are many published reports which suggest that estrogen can be synthesized in situ in lung cancer. Some disturbances in the activity and expression levels of enzymes involved in estrogen synthesis were proved. This suggests that increased amounts of sex-steroid hormones can affect cells biology and be the reason of the accelerated development and pathogenesis of lung cancer. There also exist phenomena which associate estrogenic metabolism and tobacco combustion and its carcinogenic influence on the lungs. Compounds present in cigarette smoke induce the activity of CYP1B1, the enzyme responsible for estrogenic metabolism and synthesis of their cateholic derivatives. These structures during their redox cycle are able to release reactive oxygen species or form DNA adduct, which generally leads to destruction of genetic material. This process may explain the synergistic effect of smoking and estrogens on estrogen-dependent lung cancer development.

Disturbance of Bcl-2, Bax, Caspase-3, Ki-67 and C-myc expression in acute and subchronic exposure to benzo(a)pyrene in cervix

Epidemiological studies have demonstrated that cigarette smoking is an important cofactor or an independent risk factor for the development of cervical cancer. Benzo(a)pyrene (BaP) is one of the most potent tobacco smoke carcinogens in tobacco smoke. BaP induced DNA damage and over expression in p53 cervical tissue of mice as demonstrated in our previous study. Here we present the findings of exposure to BaP on the expression of Bcl-2, C-myc, Ki-67, Caspase-3 and Bax genes in mouse cervix. Acute intraperitoneal administration of BaP (12.5, 25, 50, 100mg/kg body weight) to ICR female mice induced a significant increase in Bcl-2, C-myc, Ki-67 mRNA and protein level till 72h except in Bcl-2 at 24h with 12.5, 25, 50mg/kg as well as at 48h with 12.5mg/kg body weight post treatment. A significant increase was also seen in Caspase-3 and Bax mRNA and protein level with peak level at 24h and gradual decrease till 72h, however, the expression of caspase-3 increased while that of Bax decreased with increasing dose of Bap after 24h. In sub chronic intraperitoneal and oral gavage administration of BaP (2.5, 5, 10mg/kg body weight), similar significant increase was observed for all the examined genes as compared to the control and vehicle groups, however the expression of Bax decreased in a dose dependent manner. The findings of this study will help in further understanding the molecular mechanism of BaP induced carcinogenesis of cervical cancer.

Elevated expression of TGIF is involved in lung carcinogenesis

The purpose of this study was to explore the expression of TG-interacting factor (TGIF) in lung carcinogenesis. Malignant transformation of human bronchial epithelial (16HBE) cell was established by benzo(a)pyrene (BaP) treatment. Soft agar assay and tumor formation assay in nude mice were applied. Tumorigenesis experiment in vivo was done by BaP treatment. Western blotting, immunohistochemistry, and quantitative polymerase chain reaction were used to detect TGIF expression. We observed a higher level of TGIF messenger RNA (mRNA) in lung cancer tissues than that in paracancerous tissues. We observed significantly higher levels of TGIF mRNA and protein in A549 and H1299 cell lines than that in 16HBE cell. Increased expressions of TGIF protein and mRNA were observed in 16HBE cells induced by BaP treatment as compared to those in solvent control group. We observed significantly higher levels of TGIF mRNA and protein in 16HBE-BaP cells than that in 16HBE-control cells. We observed significantly higher levels of TGIF mRNA and protein in mice lung tissues treated with BaP than that in control group. Our results suggested that elevated expression of TGIF was involved in lung carcinogenesis.

Multifactorial ERβ and NOTCH1 control of squamous differentiation and cancer

Downmodulation or loss-of-function mutations of the gene encoding NOTCH1 are associated with dysfunctional squamous cell differentiation and development of squamous cell carcinoma (SCC) in skin and internal organs. While NOTCH1 receptor activation has been well characterized, little is known about how NOTCH1 gene transcription is regulated. Using bioinformatics and functional screening approaches, we identified several regulators of the NOTCH1 gene in keratinocytes, with the transcription factors DLX5 and EGR3 and estrogen receptor β (ERβ) directly controlling its expression in differentiation. DLX5 and ERG3 are required for RNA polymerase II (PolII) recruitment to the NOTCH1 locus, while ERβ controls NOTCH1 transcription through RNA PolII pause release. Expression of several identified NOTCH1 regulators, including ERβ, is frequently compromised in skin, head and neck, and lung SCCs and SCC-derived cell lines. Furthermore, a keratinocyte ERβ-dependent program of gene expression is subverted in SCCs from various body sites, and there are consistent differences in mutation and gene-expression signatures of head and neck and lung SCCs in female versus male patients. Experimentally increased ERβ expression or treatment with ERβ agonists inhibited proliferation of SCC cells and promoted NOTCH1 expression and squamous differentiation both in vitro and in mouse xenotransplants. Our data identify a link between transcriptional control of NOTCH1 expression and the estrogen response in keratinocytes, with implications for differentiation therapy of squamous cancer.

The regulation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumor promotion by estradiol in female A/J mice

Epidemiological studies indicate that women are at a higher risk developing lung cancer than men are. It is suggested that estrogen is one of the most important factors in lung cancer development in females. Additionally, cigarette smoke, and environmental pollutants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), may play salient roles in female lung carcinogenesis. However, the mechanisms responsible for the interaction of these factors in the promotion of lung cancer are still poorly understood. The present study was designed to explore two ideas: first, the synergistic lung tumorigenic effects of 4-(methylnitrosamino)-1-(3-pyridyl)-butanol (NNK) combined with TCDD, 17β-estradiol (E2) or both through a long-term treatment experiment, and second, to identify early changes in the inflammatory and signaling pathways through short-term treatment experiments. The results indicate that A/J mice given E2 had strong effects in potentiating NNK-induced activation of MAPK signaling, NFκB, and COX-2 expression. In the long-term exposure model, E2 had a strong tumor promoting effect, whereas TCDD antagonized this effect in A/J mice. We conclude that treatment with NNK combined with either E2 or TCDD induces lung carcinogenesis and the promotion effects could be correlated with lung inflammation. E2 was shown to potentiate NNK-induced inflammation, cell proliferation, thereby leading to lung tumorigenesis.

Smoking out reproductive hormone actions in lung cancer

Experimental and population-based evidence has been steadily accumulating that steroid hormones are fundamentally involved in the biology of the lung. Both estrogen and progesterone receptors are present in normal and malignant lung tissue, and the reproductive hormones that bind these receptors have a role in lung development, lung inflammation, and lung cancer. The estrogen receptor-β (ER-β) was discovered in the 1990s as a novel form of ER that is transcribed from a gene distinct from ER-α, the receptor previously isolated from breast tissue. Interestingly, ER-β is the predominate ER expressed in normal and malignant lung tissue, whereas inflammatory cells that infiltrate the lung are known to express both ER-α and ER-β. Although there is evidence from animal models for the preferential effects of ER-β in the lungs of females, human lung tumors from males often contain comparable numbers of ER-β-positive cells and male-derived lung cancer cell lines respond to estrogens. Lung tumors from both males and females also express CYP19 (aromatase), the rate-limiting enzyme in estrogen synthesis that converts testosterone to estrone and β-estradiol. Thus, testosterone acts as a precursor for local estrogen production within lung tumors, independent of reproductive organs. This review discusses the recent literature findings about the biology of the ERs, aromatase, and the progesterone receptor in lung cancer and highlights the ongoing clinical trials and future therapeutic implications of these findings.

Novel medium-term carcinogenesis model for lung squamous cell carcinoma induced by N-nitroso-tris-chloroethylurea in mice

Targeted treatments for lung cancer based on pathological diagnoses are required to enhance therapeutic efficacy. There are few well-established animal models for lung squamous cell carcinoma although several highly reproducible mouse models for lung adenoma and adenocarcinoma are available. This study was carried out to establish a new lung squamous cell carcinoma mouse model. In the first experiment, female A/J mice were painted topically on back skin twice weekly with 75 μL 0.013 M N-nitroso-tris-chloroethylurea for 2, 4, and 8 weeks (n = 15-20 per group) as initiation of lung lesions, and surviving mice were killed at 18 weeks. In the second experiment, mice were treated as above for 4 weeks and killed at 6, 12, or 18 weeks (n = 3 per group). Lung lobes were subjected to histopathological, immunohistochemical, immunoblotting, and ultrastructural analyses. In the case of treatment for 2, 4, and 8 weeks, incidences of lung squamous cell carcinoma were 25, 54, and 71%, respectively. Cytokeratin 5/6 and epidermal growth factor receptor were clearly expressed in dysplasia and squamous cell carcinoma. Desmosomes and tonofilaments developed in the squamous cell carcinoma. Considering the carcinogenesis model, we conclude that 2 or 4 weeks of N-nitroso-tris-chloroethylurea treatment may be suitable for investigating new chemicals for promotional or suppressive effects on lung squamous cell carcinoma.

Estrogen and insulin-like growth factor 1 synergistically promote the development of lung adenocarcinoma in mice

Estrogen receptor (ER) and insulin-like growth factor-1 receptor (IGF-1R) signaling are implicated in lung cancer progression. Based on their previous findings, the authors sought to investigate whether estrogen and IGF-1 act synergistically to promote lung adenocarcinoma (LADE) development in mice. LADE was induced with urethane in ovariectomized Kunming mice. Tumor-bearing mice were divided into seven groups: 17β-estradiol (E2), E2+fulvestrant (Ful; estrogen inhibitor), IGF-1, IGF-1+AG1024 (IGF-1 inhibitor), E2+IGF-1, E2+IGF-1+Ful+AG1024 and control groups. After 14 weeks, the mice were sacrificed, and then the tumor growth was determined. The expression of ERα/ERβ, IGF-1, IGF-1R and Ki67 was examined using tissue-microarray-immunohistochemistry, and IGF-1, p-ERβ, p-IGF-1R, p-MAPK and p-AKT levels were determined based on Western blot analysis. Fluorescence-quantitative polymerase chain reaction was used to detect the mRNA expression of ERβ, ERβ2 and IGF-1R. Tumors were found in 93.88% (46/49) of urethane-treated mice, and pathologically proven LADE was noted in 75.51% (37/49). In the E2+IGF-1 group, tumor growth was significantly higher than in the E2 group (p < 0.05), the IGF-1 group (p < 0.05) and control group (p < 0.05). Similarly, the expression of ERβ, p-ERβ, ERβ2, IGF-1, IGF-1R, p-IGF-1R, p-MAPK, p-AKT and Ki67 at the protein and/or mRNA levels was markedly higher in the ligand group than in the ligand + inhibitor groups (all p < 0.05). This study demonstrated for the first time that estrogen and IGF-1 act to synergistically promote the development of LADE in mice, and this may be related to the activation of the MAPK and AKT signaling pathways in which ERβ1, ERβ2 and IGF-1R play important roles.

Involvement of DNA polymerase β overexpression in the malignant transformation induced by benzo[a]pyrene

OBJECTIVE

To explore the relationship between DNA polymerase β (pol β) overexpression and benzo[a]pyrene (BaP) carcinogenesis.

METHODS

Firstly, mouse embryonic fibroblasts that express wild-type level of DNA polymerase β (pol β cell) and high level of pol β (pol β oe cell) were treated by various concentrations of BaP to determine genetic instability induced by BaP under differential expression levels of pol β. Secondly, malignant transformation of pol β cells by low concentration of BaP (20 μM) was determined by soft agar colony formation assay and transformation focus assay. Thirdly, the mRNA and protein levels of BaP-transformed pol β cells (named pol β-T cells) was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot, and the genetic instability of these cells were examined by HPRT gene mutation assay and random amplified polymorphic DNA (RAPD) assay.

RESULTS

Pol β cells were successfully transformed into malignant pol β-T cells by an exposure to low concentration of BaP for 6 months. Pol β-T cells exhibited increased levels of pol β gene expression, HPRT gene mutation frequency and polymorphisms of RAPD products that were comparable to those of pol β oe cells.

CONCLUSION

Pol β overexpression and its-associated genetic instability may play a key role in BaP carcinogenesis.

Silymarin prevents benzo(a)pyrene-induced toxicity in Wistar rats by modulating xenobiotic-metabolizing enzymes

Benzo(a)pyrene (B(a)P), which is commonly used as an indicator species for polycyclic aromatic hydrocarbon (PAH) contamination, has a large number of hazardous consequences on human health. In the presence of the enzyme cytochrome-P-450 1A1 (CYP1A1), it undergoes metabolic activation to form reactive intermediates that are capable of inducing mutagenic, cytotoxic, teratogenic and carcinogenic effects in various species and tissues. Research within the last few years has shown that flavonoids exhibit chemopreventive effect against these toxins. In the present study, the protective effect of silymarin (a flavonoid) against B(a)P-induced toxicity was monitored in Wistar rats by evaluating the levels of hepatic phase I (CYP1A1), phase II enzymes (glutathione-S-transferase, epoxide hydroxylases, uridinediphosphate glucuronosyltransferases, NAD(P)H: quinone oxidoreductase 1, sulfotransferases), cellular antioxidant enzyme heme oxygenase and total glutathione. The results reveal that silymarin possesses substantial protective effect against B(a)P-induced damages by inhibiting phase I detoxification enzyme CYP1A1 and modulating phase II conjugating enzymes, which were confirmed by histopathological analysis. Overall, the inhibition of CYP1A1 and the modulation of phase II enzymes may provide, in part, the molecular basis for the effect of silymarin against B(a)P.

Genetic susceptibility to lung cancer--light at the end of the tunnel?

Lung cancer is one of the most common and deadliest cancers in the world. The major socio-environmental risk factor involved in the development of lung cancer is cigarette smoking. Additionally, there are multiple genetic factors, which may also play a role in lung cancer risk. Early work focused on the presence of relatively prevalent but low-penetrance alterations in candidate genes leading to increased risk of lung cancer. Development of new technologies such as genomic profiling and genome-wide association studies has been helpful in the detection of new genetic variants likely involved in lung cancer risk. In this review, we discuss the role of multiple genetic variants and review their putative role in the risk of lung cancer. Identifying genetic biomarkers and patterns of genetic risk may be useful in the earlier detection and treatment of lung cancer patients.

Expression of the coxsackie and adenovirus receptor in human lung cancers

The aim of this study is to elucidate the relation between expression of coxsackie and adenovirus receptor (CAR) and formation of lung cancer. We investigated the expression of CAR by immunohistochemistry, Western blot and real-time RT-PCR in 120 lung cancers. We found that CAR expression in tumor tissues was significantly higher than that in normal lung tissues. CAR expression had a correlation with the histological grade of lung squamous cell carcinoma; however, there was no relationship between the CAR expression and the other clinical pathological features. In vitro, silencing or overexpression of CAR could significantly inhibit or promote colony formation, cell adhesion, and invasion in A549 cells. Our findings demonstrated that CAR may play an essential role in the formation of lung cancer.

Increased singlet oxygen-induced secondary ROS production in the serum of cancer patients

Photodynamic therapy (PDT) generates singlet oxygen ((1)O(2)) and Reactive Oxygen Species (ROS) that are counteracted by patient's defenses. As cancer treatments are among the most important PDT applications the aim of this pilot study was to determine whether the serum of cancer patients produces more or less secondary ROS or peroxides after a photoreaction as compared to healthy persons. Fifty-three volunteers and 105 cancer patients were recruited. The capacity of (1)O(2) or secondary oxidant production was found to be increased in 6 healthy donors and 36 cancer patients (23/69 women and 13/31 men p<0.007 and p<0.04) with a mean value of 1.52 as compared to 1.29 in the healthy subjects (p<0.05) when considering values higher than the normal range (norm=1±10%) or 1.1 vs. 0.85 (p<0.01) in the whole cohort. This increase correlated with a poor prognosis, TNM and SBR classification. Serum (1)O(2) deactivation capacity was impaired and secondary ROS were more produced during cancer progression. Although it is currently unclear whether this is the cause or effect of cancer, this finding may hold interest as a potential marker of cancer severity. It would also support the interest of PDT as an adjuvant for cancer treatment, even for aggressive tumors particularly when associated to surgery for bulk removal.

Vitamin E modulates cigarette smoke extract-induced cell apoptosis in mouse embryonic cells

Vitamin E (VE) can effectively prevent occurrence of lung cancer caused by passive smoking in mice. However, whether VE prevents smoking-induced cytotoxicity remains unclear. In this study, a primary culture of embryonic lung cells (ELCs) was used to observe the cytotoxic effects of cigarette smoke extract (CSE), including its influence on cell survival, cell cycle, apoptosis, and DNA damage, and also to examine the effects of VE intervention on CSE-induced cytotoxicity. Our results showed that CSE could significantly inhibit the survival of ELCs with dose- and time-dependent effects. Furthermore, CSE clearly disturbed the cell cycle of ELCs by decreasing the proportion of cells at the S and G₂/M phases and increasing the proportion of cells at the G₀/G₁ phase. CSE promoted cell apoptosis, with the highest apoptosis rate reaching more than 40%. CSE also significantly caused DNA damage of ELCs. VE supplementation could evidently inhibit or reverse the cytotoxic effects of CSE in a dose- and time-dependent manner. The mechanism of CSE effects on ELCs and that of VE intervention might involve the mitochondrial pathway of cytochrome c-mediated caspase activation. Our study validate that VE plays a clearly protective effect against CSE-induced cytotoxicity in mouse embryonic lung cells.