1-Methyl-D-tryptophan activates aryl hydrocarbon receptor, a pathway associated with bladder cancer progression.

BACKGROUND: Indoleamine 2, 3-dioxygenase-1 (IDO1) is a promising target for immunotherapy in bladder cancer (BC). IDO1 breaks-down tryptophan to generate kynurenine derivatives, which may activate the aryl hydrocarbon receptor (AHR). AHR is an important target for carcinogens, but its association with BC progression was unknown. Two IDO1 inhibitors used in clinical trials are 1-methyl-D-tryptophan (MT) and INCB240360. Because MT is an aromatic hydrocarbon, it may be a ligand for AHR. We hypothesized that AHR could be associated with BC progression and that MT could activate AHR in BC. METHODS: BC patients (n = 165) were selected from the Gene Expression Omnibus database. A cut-off point for relative expression of AHR and cytochrome 450 enzymes (CYP1A1, CYP1A2, and CYP1B1; markers of AHR activation) was determined to compare with the grade, stage, and tumor progression. For in vitro experiments, RT4 (grade 1) and T24 (grade 3) BC cells were incubated with MT and INCB240360 to evaluate the expression of AHR and CYP1A1. RESULTS: AHR activation was associated with grade, stage, and progression of BC. T24 cells express more CYP1A1 than RT4 cells. Although IDO1 expression and kynurenine production are elevated in T24 cells concomitantly to CYP1A1 expression, IDO1 inhibitors were not able to decrease CYP1A1 expression, in contrast, MT significantly increased it in both cell lines. CONCLUSION: In conclusion, it is rational to inhibit IDO1 in BC, among other factors because it contributes to AHR activation. However, MT needs to be carefully evaluated for BC because it is an AHR pathway agonist independently of its effects on IDO1.

Genotoxic impact of long-term cigarette and waterpipe smoking on DNA damage and oxidative stress in healthy subjects.

Although a plethora of studies have examined tobacco smoke-cancer disease association, the involvement of cellular genetic toxicity remains unclear. Therefore, the present study provides molecular evidence for a pathway involved in the DNA damage induced by long-term cigarette and waterpipe smoke in human subjects. The study population consisted of 45 subjects who were divided into three groups; healthy nonsmokers group, cigarette smokers group, and waterpipe smokers group. A questionnaire and consent form was distributed and signed by all participants. Total RNA was extracted from the blood using PAXgene Blood RNA Kit and mRNA expression levels of target genes were quantified by RT-PCR. Our results showed that 80% of the participants smoke 20-39 cigarettes/day, whereas 12% smoke more than 40 cigarettes/day. With regard to waterpipe smoke, the majority (46%) smoke more than 5 times/week. Both cigarette and waterpipe smokers showed increased the plasma levels 8-hydroxy-2'-deoxyguanosine (8-OHdG), of DNA damage marker. In addition, the mRNA expression levels of DNA repair genes (OGG1 and XRCC1) were significantly inhibited in both cigarette and waterpipe smokers groups by 30% and 60%, respectively. This was associated with a marked decrease (50%) in the expression of detoxifying genes (NQO1 and GSTA1) with an increase in CYP1A1 mRNA expression, a cancer-activating gene. Both cigarette and waterpipe smokers increased in the plasma concentrations of several toxic heavy metals such as Cd (130%), Pb (47%), and Ni (30%). In conclusion: the present findings clearly explore the genotoxic effect of cigarette and waterpipe smoking on human DNA.

Serum Levels of Aryl Hydrocarbon Receptor, Cytochromes P450 1A1 and 1B1 in Patients with Exacerbated Psoriasis Vulgaris.

The aryl hydrocarbon receptor (AhR) is highly expressed in psoriasis skin lesions. The aim of this study was to investigate serum concentrations of AhR, cytochromes P450 (CYP) 1A1 and 1B1 in patients with exacerbated psoriasis vulgaris treated with combined therapy of ultraviolet radiation (UVR) and crude coal tar. The analyses were performed by using enzyme-linked immunosorbent assays. Before the treatment, the patients had significantly higher serum levels of AhR and CYP1A1 than healthy controls. AhR median noticeably decreased after the therapy; nevertheless, it remained significantly higher compared to the controls. CYP1A1 levels measured before and after the therapy did not differ significantly. Serum CYP1A1 positively correlated with AhR values before and after the treatment. The serum values of CYP1B1 were very low and we did not see any differences between the study group and the control group. The study demonstrated that serum levels of AhR and CYP1A1 could indicate their immunopathological and metabolic roles in exacerbated psoriasis.

Genetic variation in the CYP1A1 gene is related to circulating PCB118 levels in a population-based sample.

Several of the polychlorinated biphenyls (PCBs), i.e. the dioxin-like PCBs, are known to induce the P450 enzymes CYP1A1, CYP1A2 and CYP1B1 by activating the aryl hydrocarbon receptor (Ah)-receptor. We evaluated if circulating levels of PCBs in a population sample were related to genetic variation in the genes encoding these CYPs. In the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study (1016 subjects all aged 70), 21 SNPs in the CYP1A1, CYP1A2 and CYP1B1 genes were genotyped. Sixteen PCB congeners were analysed by high-resolution chromatography coupled to high-resolution mass spectrometry (HRGC/ HRMS). Of the investigated relationships between SNPs in the CYP1A1, CYP1A2 and CYP1B1 and six PCBs (congeners 118, 126, 156, 169, 170 and 206) that captures >80% of the variation of all PCBs measured, only the relationship between CYP1A1 rs2470893 was significantly related to PCB118 levels following strict adjustment for multiple testing (p=0.00011). However, there were several additional SNPs in the CYP1A2 and CYP1B1 that showed nominally significant associations with PCB118 levels (p-values in the 0.003-0.05 range). Further, several SNPs in the CYP1B1 gene were related to both PCB156 and PCB206 with p-values in the 0.005-0.05 range. Very few associations with p<0.05 were seen for PCB126, PCB169 or PCB170. Genetic variation in the CYP1A1 was related to circulating PCB118 levels in the general elderly population. Genetic variation in CYP1A2 and CYP1B1 might also be associated with other PCBs.

A multi-biomarker assessment of single and combined effects of norfloxacin and sulfamethoxazole on male goldfish (Carassius auratus).

In the present study, the sublethal effects of norfloxacin alone and in combination with sulfamethoxazole in goldfish (Carassius auratus) were investigated, the biomarkers including acetylcholinesterase (AChE) in brain, 7-ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST), and superoxides dismutase (SOD) activities in liver, vitellogenin (Vtg) in serum and DNA damage in gonad were determined after 1, 2, 4 and 7 days of exposure. Brain AChE activity was significantly inhibited by norfloxacin (≥0.4 mg/L) after 4 and 7 days and the mixtures with sulfamethoxazole (≥0.24 mg/L) after 4 days of exposure, and significant concentration-response relationships were obtained. Liver EROD, GST and SOD activities were significantly increased by the individual and mixed pharmaceuticals in most cases and exhibited analogously bell-shaped concentration-response curves. Serum Vtg was increased by the highest concentration of norfloxacin and two higher concentrations of the mixtures. Higher concentrations of the test antibiotics induced significant DNA damage in a concentration- and time-dependent manner. The results indicated that selected antibiotics possesses cytotoxic and genotoxic potential against the non-target organism C. auratus.

Potentially estrogenic polychlorinated biphenyls congeners serum levels and its relation with lung cancer.

Lung cancer is the most common cancer in the world. The main cause of lung cancer is cigarette smoke; however, other important genetic and environmental risk factors play a significant role in the development of lung cancer. Among these factors, occupational and accidental exposure to polychlorinated biphenyls (PCBs) has been associated with an increased risk in lung cancer, suggesting that PCBs could be potent carcinogens. The aim of the present study was to investigate the association between PCB exposure levels, CYP1A1 polymorphisms and the risk of lung cancer. This study enrolled newly diagnosed lung cancer patients. Environmental and occupational information related to the patients studied was collected. Blood samples were taken for the measurement of serum levels of 20 PCB congeners and for CYP1A1 polymorphism analysis. The serum levels of two PCB congeners with potential estrogenic activity were higher in lung cancer patients. The risk of lung cancer was found to correlate with age, gender, smoking history and with agricultural workers, as well as with congener 18. No differences were found in the frequency of CYP1A1 polymorphisms. Furthermore, we did not find a correlation between CYP1A1 polymorphisms and PCB serum levels. The high levels of PCB with estrogenic activity found in our cases, could promote lung cancer inducing cell proliferation in non-neoplastic and neoplastic lung cells via ERß; inducing the formation of DNA adducts, producing oxidative stress with the subsequent DNA damage and increasing the endogenous catechol levels by catechol-O-methyl transferase (COMT) inhibition.

Polymorphisms in PAH metabolising enzyme CYP1A1 in colorectal cancer and their clinicopathological correlations.

CYP1A1 enzyme is integral to the biotransformation of polycyclic aromatic hydrocarbons to carcinogenic compounds. This study aimed to screen mutations in exon 7 (ex7) of CYP1A1 and investigate its clinicopathological correlations in fresh tissue samples from 85 patients (42 women; 43 men) with colorectal carcinoma (CRC). Tumour tissues and matched non-neoplastic mucosa tissues were collected prospectively. Genomic DNA was extracted from all tissues, and subject to high-resolution melt curve analysis for CYP1A1-ex7. Sanger sequencing was employed to detect specific mutations. Three known single nucleotide polymorphisms (SNPs) were identified in both tumour and matched non-neoplastic tissue for the same individual. Of the 85 patients, one third (n = 28) harboured either rs1048943, rs1799814, or rs41279188. Patients who had a SNP at ex7 of CYP1A1 were significantly more likely to be over 65 years of age (p = 0.015). Furthermore, individuals harbouring a SNP at exon7 showed a low incidence of perineural cancer infiltration (p = 0.025) when compared to the wild-type population. Overall, polymorphisms at exon 7 of CYP1A1 are present in patients with CRC and associated with a few clinicopathological characteristics.

Assessment of estrogenic contamination and biological effects in Lake Taihu.

Lake Taihu is the third largest freshwater lake in China and is contaminated with xenoestrogens associated with high population density, intensive livestock and aquatic breeding activities. A field study in Lake Taihu was conducted using the goldfish (Carassius auratus) as an indicator organism. Several biological markers were selected to assess the extent of estrogenic contamination. Changes in serum vitellogenin (VTG), and gill 7-Ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and reduced glutathione (GSH) were measured in caged juvenile goldfish for 28 days in seven locations in northern Lake Taihu. Bioassay showed VTG increased 0.64-2.42 folds over time in goldfish collected from five stations and GSH decreased in samples from all seven stations after 7 days of exposure. EROD levels increased continually in fish collected at all the seven stations and the highest concentrations occurred at day 21. GST activity increased significantly at 7 days. The concentration of the target estrogens estrone (E(1)), 17ß-estradiol (E(2)), ethinylestradiol (EE(2)), octylphenol (OP), diethylstilbestrol (DES), nonylphenol (NP) and bisphenol A (BPA) were determined in lake water at the sampling stations. Each individual estrogen concentration measured was multiplied by its relative potency to gain the estradiol equivalent (EEQ). There was an obvious correlation between the concentration of VTG and the total EEQ for all seven locations (P < 0.001). The biomarker VTG, EROD, GST and GSH assays and chemical analysis might be used to illustrate the potential risk in Lake Taihu.

Increased cytochrome P4501B1 gene expression in peripheral leukocytes of municipal waste incinerator workers.

Incinerator workers are exposed to polycyclic aromatic hydrocarbons (PAHs) and dioxins in workplace. Previous studies indicated that aryl hydrocarbon receptor activation, following by increased cytochrome P4501A1 (CYP1A1) and 1B1 (CYP1B1) activity and expressions, was required for PAHs and dioxin induced toxicities. This study investigated whether municipal waste incinerator workers with frequent exposure to PAHs/dioxins in fly/bottom ash had increased CYP1A1 and CYP1B1 expressions in peripheral leukocytes and assessed whether CYP1B1*3 polymorphism modified the association between PAHs/dioxins exposure and CYP1B1 expressions. Based on job contents and time-activity profiles, 112 workers were classified into high exposure, medium exposure and control groups. CYP1A1 and CYP1B1 gene expressions in workers' leukocytes were determined with the real-time reverse transcriptase polymerase chain reaction method. After taking into account age, gender and smoking in the multiple regression analyses, CYP1B1, but not CYP1A1, levels were significantly higher in the high and medium exposure groups than in the control group, and there was a statistically significant interaction between exposure group and CYP1B1 genotype. These results suggested that CYP1B1 gene expression could be a potential biomarker of biologically effective dose for occupational exposure to PAHs/dioxins and CYP1B1*3 polymorphism modified effects of occupational exposures on CYP1B1 expression.

Responses of shortfin eel (Anguilla australis) exposed in situ to pulp and paper effluent.

The responses of shortfin eel (Anguilla australis) to discharges from two pulp and paper mills, municipal wastewater, and a geothermal power plant wastewater were examined. Eels were caged at 3 sites along the Tarawera River, North Island, New Zealand, to explore effects of a 3-wk exposure down a contamination gradient (Ref --> D1 --> D2). Most of the observed effects were seen in eels caged at the furthest downstream site (D2), below all the discharge areas. General hematology in eels was unaffected, as measures did not differ markedly at the two downstream sites compared with the reference site. At D2, eels were significantly lighter per unit length (reduced condition factor), although liver and spleen size (LSI and SSI) were unaffected. Significantly elevated circulating sex steroid concentrations (testosterone and estradiol) were measured in D2 eels and increasing sex steroid levels at both sites downstream of the reference site were observed. Significant ethoxyresorufin O-deethylase (EROD) activity induction was seen in D2 eels and bile chemistry showed significant accumulation of pyrene and retene equivalents. However, significantly greater concentrations of total resin acids were found in the bile of eels from the intermediate site (D1), between the two pulp and paper mills. The higher polycyclic aromatic hydrocarbon (PAH) equivalents found in the bile of D2 eels suggest that resin acid neutrals, particularly retene, are responsible for some of the effects observed in eels at the furthest downstream exposure site. Levels of pulp and paper mill extractives in sediment, including the PAH retene, support this conclusion.

Induction of hepatic cytochromes P450 in dogs exposed to a chronic low dose of polychlorinated biphenyls.

Induction of cytochrome P450 isoforms, specifically CYP1A1, and their catalytic activities are potential biomarkers of environmental contamination by polychlorinated biphenyls (PCBs). In this study, dogs were exposed to 25 ppm or 5 ppm Aroclor 1248 (PCB mixture) daily in their diet for 10 or 20 weeks, respectively. Relative to controls, hepatic microsomes from dogs dosed with PCBs had higher levels of CYP1A1 detected in immunoblots and higher levels of EROD activity, but low levels of induction for CYP2B and PROD activity. Concentrations of 96 PCB congeners in serum and liver were evaluated using capillary chromatography. Results showed that all dogs exposed to PCB mixtures had higher levels of PCB in serum and liver. Dogs preferentially sequestered highly chlorinated PCB congeners in liver relative to serum. With these experiments, we demonstrated that EROD activity was a potentially sensitive marker of PCB exposure at 5 and 25 ppm. Furthermore, CYP1A1 and EROD activity were maximally induced in dogs consuming dietary concentrations only 2.5 times the maximal permissible level for human food (FDA). The value of CYP1A1 induction as a biomarker of PCB exposure was tenuous because neither CYP1A1 levels nor EROD activity correlated with total PCB body burden. However, a small subset of congeners were identified in liver that may strongly influence EROD and PROD induction. Finally, two dogs in the 25 ppm dose group were fasted for 48 h. After 24 h of fasting, several new congeners appeared in the serum and remained in the serum for the remainder of the fast. The fast caused a 293% increase in PCB concentration in serum. This increase has strong implications regarding mobilization of toxic PCBs in wildlife during fasting (e.g., migration, hibernation).

Cytochrome P450 1A1 in rat peripheral blood lymphocytes: inducibility in vivo and bioactivation of benzo[a]pyrene in the Salmonella typhimurium mutagenicity assay in vitro.

The presence and inducibility of CYP1A1 in freshly isolated peripheral blood lymphocytes was examined in untreated rats and in rats pretreated with agents known to induce the enzyme in other tissues, as well as dexamethasone [CAS #50-02-2], which is not commonly associated with CYP1A1 induction. CYP1A1 but not CYP1A2 was detected by Western blot analysis of lymphocytes from untreated rats and was induced in lymphocytes from rats treated with the known CYP1A inducers beta-naphthoflavone [CAS #6051-87-2] or 3-methylcholanthrene [CAS #56-49-5] (7.3-fold), cigarette smoke (2. 8-fold), and pyridine [CAS #108-86-1] (2.6-fold). CYP1A1 was also induced in lymphocytes from rats treated with the nonprototypic inducer dexamethasone (17.7-fold) or bromobenzene [CAS #108-86-1] (3. 9-fold). Lymphocyte homogenate from rats treated with the inducers also catalyzed NADPH-dependent bioactivation of benzo[a]pyrene [CAS #50-32-8] to mutagens. The benzo(a)pyrene mutagenicity was detected using Salmonella typhimurium TA100 in the Ames test, and correlated positively with lymphocyte CYP1A1 content. The data show that CYP1A1 is present in rat peripheral blood lymphocytes in vivo, and is inducible by prototypic, as well as nonprototypic, inducers of the enzyme.

Seasonal variation of plasmatic and hepatic vitellogenin and EROD activity in carp, Cyprinus carpio, in relation to sewage treatment plants.

Concern about the health of aquatic fauna living in waters containing biologically active levels of estrogenic compounds is particularly focused on the effects on their reproductive success. To that end, carp, Cyprinus carpio, a feral fish living in warm waters of Southern Europe (NE Spain), were selected for signs of estrogenicity. The study area covered two tributaries (the Anoia and the Cardener) of the Llobregat River both known to be polluted by estrogenic compounds. The estrogenicity in the carp was measured as vitellogenin (VTG) presence in males and alterations in VTG levels in females, over a 6-month period, embracing both the pre- and post-spawning seasons. VTG content was measured in both the plasma and liver, the latter being the organ that synthesizes it. Also, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity was recorded, as interactions of xenoestrogens and oestradiol have been reported to affect this enzymatic activity. The estrogenicity of these rivers was more evident in the Anoia at the location downstream from the sewage treatment plant (STP), by elevated levels of VTG in males and by the presence of some intersex individuals. In the Cardener, no intersex fish were found and male plasmatic VTG was not so highly elevated. However presence of hepatic VTG, in up to 54% of the male fish analyzed, proved exposure to xenoestrogens. In females, VTG fluctuated according to the biological cycle with a plasmatic peak in May and an earlier maximal in the liver. However, this pattern was altered in the locations with higher xenoestrogens presence. EROD activity showed differences between sexes, with higher activity in males than females, as well as site-related differences (up to one order of magnitude) in the same river. These differences were even greater than those detected between rivers. A seasonal trend was also seen in EROD activity with higher induction towards the summer in both males and females.

Occupational exposure to polycyclic aromatic hydrocarbons suppresses constitutive expression of CYP1B1 on the transcript level in human leukocytes.

Expression patterns of the cytochromes P450 CYP1A1 and CYP1B1 have been analyzed on the transcript level in leukocytes of persons (n = 30) occupationally exposed to polycyclic aromatic hydrocarbons (PAH). To assess effects on expression levels results were compared with data obtained from a non-exposed control group (n = 68). CYP1B1 transcripts can be detected in all subjects of the control group but vary largely in their levels (factor 35). Statistical analysis shows that this variability is neither due to the age of the persons nor due to cigarette smoking. Furthermore, there is no difference in expression levels between genders. In contrast to CYP1B1, CYP1A1 is detectable in only 14% of the subjects. People involved in graphite electrode production and exposed to PAH show largely decreased CYP1B1 transcript levels. In 67% of the subjects, CYP1B1 is no more detectable at all. Vice versa, expression of CYP1A1 is increased in exposed persons so that 80% become positive for CYP1A1 vs. 14% of the control group. The results show that occupational exposure to PAH apparently leads to effect-relevant internal doses. Both, suppression of CYP1B1 and induction of CYP1A1 in leukocytes can be used as exposure parameters proving both enzymes to be suitable biomarkers of exposure. The suppression of CYP1B1 is an unexpected effect which needs further investigation. It is discussed that CYP1B1 and CYP1A1 indeed share a common Ah receptor mediated transcriptional regulation but that differences in promoter structure of the two genes and tissue-specific expression profiles of transcription factors may cause a differential expression behaviour.

EROD activity, serum SDH and PAH biliary metabolites in sand flathead (Platycephalus bassensis) collected in Port Phillip Bay, Australia.

In order to evaluate the health status of fish inhabiting Port Phillip Bay, Australia, southern sand flathead (Platycephalus hassensis, N = 133) were collected at six stations throughout the Bay. Fish had a similar serum sorbitol dehydrogenase (SDH) activity level (p = 0.12), indicating that they were not experiencing hepatocellular injuries. Ethoxyresorufin-O-deethylase (EROD) activity was generally lower in the non-urbanized and non-industrialized southern part of the Bay. The highest EROD activity was observed in Hobson Bay, the closest station from Melbourne city. Naphthalene-type biliary metabolites were also highest in Hobson Bay with intermediate levels found in Corio Bay where refineries are present. An opposite trend was observed with the pyrene-type bile metabolites, the highest levels being observed in Corio Bay while intermediate levels were found in Hobson Bay. The ratio of naphthalene-type to benzo(a)pyrene (B(a)P)-type metabolites indicate that relatively to other sites sampled in Port Phillip Bay, Corio Bay is subjected to enriched petroleum hydrocarbons of pyrolytic origin. Temporal trends indicate that the availability of xenobiotics to fish remained unchanged over the 1990s.

Validation of a cell culture bioassay for detection of petroleum exposure in mink (Mustela vison) as a model for detection in sea otters (Enhydra lutris).

OBJECTIVE: To validate a luciferase bioassay, which is based on a recombinant mouse hepatoma cell line, for the detection of exposure to petroleum in mustelid species. ANIMALS: 122 American mink (Mustela vison) and 15 sea otters (Enhydra lutris). PROCEDURES: Mink were exposed to Bunker C fuel oil or Alaska North Slope crude oil externally as a single exposure or internally via low dose concentrations in their ration for 6 months. Serum samples were analyzed for cytochrome P450 1A1 induction by quantification of luciferase activity in the bioassay. Mink liver specimens were also evaluated for cytochrome P450 1A1 induction by quantification of ethoxyresorufin-o-deethylase activity. Serum collected from exposed and unexposed sea otters was also analyzed using the luciferase bioassay. RESULTS: Serum samples from mink externally exposed to petroleum had significantly increased luciferase activities at 1 week after exposure. Serum samples taken at later time points or from mink exposed to either product in the ration did not cause significant luciferase induction. Samples from otters exposed to petroleum had significantly higher luciferase induction as compared with samples from otters not exposed to petroleum at 2 and 8 years after the spill. Cytochrome P450 1A1 activity in liver specimens collected from mink that were internally exposed through diet was significantly increased at the conclusion of our study. CONCLUSION AND CLINICAL RELEVANCE: The luciferase bioassay is a sensitive and specific method for determining recent exposure to petroleum in mink. The lack of luciferase activity in serum samples collected from mink greater than 1 week after experimental exposure was likely attributable to lower overall petroleum exposure in our trial, compared with natural exposures.

Expression patterns of carcinogen detoxifying genes (CYP1A1, GSTP1 & GSTT1) in HNC patients.

Carcinogen detoxifying genes may be involved in pathogenesis of head and neck cancer (HNC). CYP1A1 is phase I enzyme that converts carcinogens into water soluble compounds which are easily excreted from body. GSTs constitute phase II detoxification enzymes that recognize these highly electrophilic compounds and detoxify them. Abnormal expression of these genes can potentially lead to cancer initiation. In present study, we analyzed protein expression of these genes in a total of 192 HNC patients and noncancerous healthy control serum samples screened for GSTs specific activity by ELISA. Furthermore, expression of these molecules was also determined in 49 HNC tissues/ adjacent control tissue by immunohistochemistry with specific antibodies. Mean serum GSTs specific activity was found to be 7.7 (+11.5)U/L in HNC patients and 11.4 (+7.5)U/L in controls. Significant decrease (P < 0.05) in GSTs specific activity was observed in HNC patients compared with controls (P < 0.001). Data for immunohistochemistry showed that CYP1A1 and GSTT1 was down expressed whereas GSTP1 was over expressed in HNC tissues compared with adjacent normal control tissues. Results of immunohistochemistry revealed 63 % HNC tissues had weak, 27 % moderate and 10 % strong staining for CYP1A1. For GSTT1, 27 % HNC tissues had no staining, 49 % weak staining, 16 % moderate and 8 % strong staining. Similarly for GSTP1, percentages for weak, moderate and strong staining were 6 %, 12 % and 82 % respectively. These reduced proteins observed in cancer patients highlight a potential breach on DNA repair mechanism when compared with control. Thus altered expression of these detoxifying molecules may collectively contribute to HNC development in Pakistani population.

Pharmacogenetics of olanzapine metabolism.

The pharmacokinetics of the atypical antipsychotic, olanzapine, display large interindividual variation leading to multiple-fold differences in drug exposure between patients at a given dose. This variation in turn gives rise to the need for individualized dosing in order to avoid concentration-dependent adverse effects or therapeutic failure. Genetically determined differences in olanzapine metabolism represent a less studied source of variability in comparison to environmental and physiological factors. In this review, we summarize available in vitro and in vivo data addressing the influence of polymorphisms in drug-metabolizing enzymes on olanzapine serum exposure. The polymorphic CYP2D6 enzyme appears to have no significant influence on olanzapine steady-state serum concentrations. The formation of the various olanzapine metabolites is influenced by polymorphisms in the genes coding for CYP1A2, CYP1A expression regulator AHR, UGT1A4 and UGT2B10, as well as FMO3. An impact on steady-state olanzapine serum concentrations has been suggested for variants of CYP1A2 and UGT1A4, with somewhat conflicting findings. The potential involvement of FMO1 and CYP3A43 in olanzapine disposition has also been suggested but needs future validation.

Reciprocal inhibiting interactive mechanism between the estrogen receptor and aryl hydrocarbon receptor signaling pathways in goldfish (Carassius auratus) exposed to 17ß-estradiol and benzo[a]pyrene.

In the aquatic environment, both the estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) responses are established biomarkers for assessing exposure to pollutants. These receptor responses can also be affected by the presence of other classes of pollutants and may result in misinterpretation of existing pollution. In this study, we investigated the interaction between ER-vitellogenin (VTG) and AhR-cytochrome P450 1A (CYP1A) signaling pathways in goldfish (Carassius auratus) after 10 days exposure to pollutants. 17ß-Estradiol (E(2)) and benzo[a]pyrene (BaP) were selected as the ER and AhR agonists, respectively. The messenger RNA (mRNA) expression of ER-VTG and AhR-CYP1A in liver was determined using quantitative real-time polymerase chain reaction (QRT-PCR). VTG, endogenous E(2) and 7-ethoxyresorufin-O-deethylase (EROD) were also studied. Exposure to E(2) and BaP alone significantly induced the gene expression of ERα-VTG and AhR2-CYP1A, respectively. Moreover, the obvious expression of related proteins was also observed. However, these inductions were significantly reduced after combined exposure to E(2) and lower concentrations of BaP (20 and 50 µg/L), indicative of a reciprocal inhibiting ER-AhR interaction. However, high concentrations (100 µg/L) of BaP did not affect the E(2)-induced gene expression. Changes in VTG protein were in accordance with the expression of VTG mRNA, and more VTG protein was observed in liver than in serum. The induced endogenous E(2) levels were suppressed by the presence of BaP. While the gene expression of CYP1A showed a concentration-dependent increase, EROD induction exhibited a bell-shaped concentration-response curve. Taken together, these results demonstrate a reciprocal inhibiting mode of ER-AhR interactions and may lead to a possible underestimation of actual exposure.

Estrogenic and anti-estrogenic effects of wood extractives present in pulp and paper mill effluents on rainbow trout.

Wood extractives present in pulp and paper mill effluents may cause reproductive disturbances in fish. A chronic-exposure toxicity experiment using immature rainbow trout (Oncorhynchus mykiss) was conducted in order to assess the endocrine disrupting effects of two Chilean pulp and paper mill specific extracts (solid phase extraction, SPE) obtained from primary and secondary treated effluents. The (anti)estrogenic potencies and toxicity of the wood extractives regularly present in pulp mill effluent such as dehydroabietic acid (DHAA), beta-sitosterol (BS), and model estrogen 17beta-estradiol (E2) were evaluated by analysis of plasma vitellogenin (VTG) levels, gonadal somatic index (GSI) and liver ethoxyresorufin-O-deethylase (EROD) activity, respectively. The protocol involved the use of multiple intra-peritoneal injections (1 injection every 7 days for a total exposure period of 28 days). Analysis of variance/covariance, demonstrated no differences associated with fish gender other than GSI. The phytosterol BS, E2 and both pulp mill effluent extracts showed significant inductions of EROD and increased VTG levels after 4, 7, 14, 21 and 28 of exposure. While fish injected with secondary treated effluent extract showed a delayed induction in VTG levels compared to primary effluent injected fish, no effects on VTG and EROD levels were observed in DHAA injected fish. Moreover simultaneous injection of DHAA+E2 reduced the VTG levels found in E2 injected fish, indicating a potential indirect anti-estrogenic effect of this resin acid. The results of this study indicate that Chilean pulp and paper mill effluent extracts are estrogenic in rainbow trout males and females.