CYP2D6 genotype predicts tamoxifen discontinuation and drug response: a secondary analysis of the KARISMA trial.

BACKGROUND: Guidelines regarding whether tamoxifen should be prescribed based on women's cytochrome P450 2D6 (CYP2D6) genotypes are conflicting and have caused confusion. This study aims to investigate if CYP2D6 metabolizer status is associated with tamoxifen-related endocrine symptoms, tamoxifen discontinuation, and mammographic density change. PATIENTS AND METHODS: We used data from 1440 healthy women who participated the KARISMA dose determination trial. Endocrine symptoms were measured using a modified Functional Assessment of Cancer Therapy - Endocrine Symptoms (FACT-ES) questionnaire. Change in mammographic density was measured and used as a proxy for tamoxifen response. Participants were genotyped and categorized as poor, intermediate, normal, or ultrarapid CYP2D6 metabolizers. RESULTS: The median endoxifen level per mg oral tamoxifen among poor, intermediate, normal and ultrarapid CYP2D6 metabolizers were 0.18 ng/ml, 0.38 ng/ml, 0.56 ng/ml and 0.67 ng/ml, respectively. Ultrarapid CYP2D6 metabolizers were more likely than other groups to report a clinically relevant change in cold sweats, hot flash, mood swings, being irritable, as well as the overall modified FACT-ES score, after taking tamoxifen. The 6-month tamoxifen discontinuation rates among poor, intermediate, normal, and ultrarapid CYP2D6 metabolizers were 25.7%, 23.6%, 28.6%, and 44.4%, respectively. Among those who continued and finished the 6-month tamoxifen intervention, the mean change in dense area among poor, intermediate, normal, and ultrarapid CYP2D6 metabolizers were -0.8 cm2, -4.5 cm2, -4.1 cm2, and -8.0 cm2 respectively. CONCLUSIONS: Poor CYP2D6 metabolizers are likely to experience an impaired response to tamoxifen, measured through mammographic density reduction. In contrast, ultrarapid CYP2D6 metabolizers are at risk for exaggerated response with pronounced adverse effects that may lead to treatment discontinuation.

Cytochrome P450 1A1 gene regulation by UVB involves crosstalk between the aryl hydrocarbon receptor and nuclear factor kappaB.

UVB induces the expression of genes controlled by the aryl hydrocarbon receptor (AhR), a transcription factor that has been implicated in the UV stress response. In this study, we used the human hepatoma cell line HepG2 to investigate in more detail the effects of UVB irradiation on AhR activation and induction of cytochrome P450 1A1 (CYP1A1), a highly AhR-responsive gene. The CYP1A1 enzyme efficiently degrades 6-formylindolo[3,2-b]carbazole (FICZ), a high affinity ligand and suggested endogenous activator of the AhR. We show that physiologically relevant doses of UVB suppress CYP1A1 gene expression immediately after irradiation, but induce its expression later in an AhR-dependent manner. The initial repression phase of CYP1A1 transcription was mediated by another UVB-inducible transcription factor, the nuclear factor kappaB (NFkappaB). Crosstalk between AhR and NFkappaB signaling has earlier been implicated to control CYP1A1 expression following stimulation by xenobiotics and cytokines. Now, our findings clearly indicate a role of NFkappaB also in UVB-dependent AhR signaling. We also observed that UVB reduced the catalytic activity of the CYP1A1 enzyme. Thereby, UVB attenuated the clearance of FICZ, which led to prolonged AhR activation. We further noted that repeated irradiation with UVB or H(2)O(2) treatment shifted the cells into a refractory state in which AhR signaling could not be efficiently activated by UVB or H(2)O(2), but by ligands. Together, our results suggest that the NFkappaB-mediated initial suppression of CYP1A1 as well as the unresponsiveness of AhR signaling to repeated irradiation may be part of a protective cellular UV stress response.

Brain metastases admissions in Sweden between 1987 and 2006.

BACKGROUND: Brain metastases (BM) constitute the most common intracranial tumours and are associated with considerable morbidity and mortality. Population-based studies of the epidemiology and time trends of BM are scarce. METHODS: A population-based cohort of patients admitted to hospital with BM in Sweden between 1987 and 2006 (n=15,517) was identified and linked to nationwide registers of cancer incidence and death. Primary cancer types were assessed and time to hospitalisation and death was computed. RESULTS: The annual age-adjusted incidence rate of hospitalisation for BM doubled from 7 to 14 patients per 100,000 between 1987 and 2006. The most common primary tumours among women were lung (33%), breast (33%) and colorectal cancer (7%), and among men lung cancer (44%), malignant melanoma (12%) and colorectal cancer (9%). The increase was most evident for BM patients with lung cancer (both sexes) and breast cancer (women). Survival was short, with a median of 2.7 months. It varied little by cancer type and did not improve over calendar time. CONCLUSION: The number of patients admitted with BM has increased rapidly in Sweden. In spite of recent improvements in the prognosis of common primary cancer types, any parallel improvement among patients with advanced cancer and BM is not indicated.

Interactions of polybrominated diphenyl ethers with the aryl hydrocarbon receptor pathway.

Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants that have been in use as additives in various consumer products. Structural similarities of PBDEs with other polyhalogenated aromatic hydrocarbons that show affinity for the aryl hydrocarbon receptor (AhR), such as some polychlorinated biphenyls, raised concerns about their possible dioxin-like properties. We studied the ability of environmentally relevant PBDEs (BDE-47, -99, -100, -153, -154, and -183) and the "planar" congener BDE-77 to bind and/or activate the AhR in stably transfected rodent hepatoma cell lines with an AhR-responsive enhanced green fluorescent protein (AhR-EGFP) reporter gene (H1G1.1c3 mouse and H4G1.1c2 rat hepatoma). 7-Ethoxyresorufin-O-deethylation (EROD) was used as a marker for CYP1A1 activity. Dose- and bromination-specific inhibition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced responses was measured by their ability to inhibit the induction of AhR-EGFP expression and EROD activity. Individual exposure to these PBDEs did not result in any increase in induction of AhR-EGFP or CYP1A1 activity. The lower brominated PBDEs showed the strongest inhibitory effect on TCDD-induced activities in both cell lines. While the highest brominated PBDE tested, BDE-183, inhibited EROD activity, it did not affect the induction of AhR-EGFP expression. Similar findings were observed after exposing stably transfected human hepatoma (xenobiotic response element [XRE]-HepG2) cells to these PBDEs, resulting in a small but statically significant agonistic effect on XRE-driven luciferase activity. Co-exposure with TCDD resulted again in antagonistic effects, confirming that the inhibitory effect of these PBDEs on TCDD-induced responses was not only due to direct interaction at receptor level but also at DNA-binding level. This antagonism was confirmed for BDE-99 in HepG2 cells transiently transfected with a Gal4-AhR construct and the corresponding Gal4-Luc reporter gene. In addition, a chromatin immunoprecipitation assay further confirmed that BDE-99 could bind to the AhR and activate the AhR nuclear translocation and dioxin responsive element (DRE) binding in the context of the CYP1A1 promoter. However, the transactivation function of the BDE-99-activated AhR seems to be very weak. These combined results suggest that PBDEs do bind but not activate the AhR-AhR nuclear translocator protein-XRE complex.

Impact of ionizing radiation and genetic background on mammary tumorigenesis in p53-deficient mice.

Loss of p53 function is known to compromise cell cycle regulation, inductionof apoptosis, and DNA damage repair and can facilitate neoplastic transformation of cells. Mutations in the p53 gene are identified frequently in breast carcinomas. Li-Fraumeni patients inheriting a mutant p53 allele have an increased risk for developing tumors including breast cancer. Although mouse lines carrying mutations in the p53 gene have been generated, they die primarily of lymphoma and thus to date provide a limited model for the study of this disease and the role of p53 in nonfamilial breast cancer. An increasing body of literature suggests that the incidence of various tumors is determined largely by the genetic background on which mutations are studied. In addition, population studies and studies in animals suggest that environmental factors, together with genetic factors, determine overall risk for development of specific types of tumors. We therefore examined the impact of genetic background together with exposure to ionizing radiation on the development of tumors, particularly mammary tumors, in p53-deficient animals. We report here that modifier alleles present in the BALB/c strain increase the incidence of hemangiosarcomas [15 of 53 (28.3%); P = 0.0007] in p53(-/-) mice above rates reported previously in p53(-/-) mice on a mixed background as compared to the incidence observed in DBA/p53(-/-) mice. However, no increase in the frequency of mammary tumors is seen in these mice or in p53(-/-) DBA/2 animals, nor was an increase in mammary tumors observed in the DBA/2 p53(+/-) mice, even after exposure to 5 Gy of whole-body ionizing radiation. In contrast, a significant increase in the incidence of mammary tumors was observed in similarly treated BALB/c p53(+/-) mice (37.3% versus 6.8%; P = 0.0007). This was accompanied by a comparable decrease in the incidence of lymphomas. These results show that environmental agents together with genetic factors can increase the frequency and decrease the latency of mammary tumors, leading to an incidence similar to that observed in Li-Fraumeni syndrome. Furthermore, it suggests that the risk of development of a particular type of tumor by individuals deficient in p53 after exposure to damaging agents can be influenced by modifier alleles.

Transcriptional and post-translational regulation of CYP1A1 by primaquine.

Regulation of the CYP1A1 gene has been shown to involve the aryl hydrocarbon receptor and the CYP1A1 gene expression is induced by AhR ligands. Primaquine is an antimalarial agent that does not exhibit the structural properties of a classical AhR ligand. We have evaluated the mechanisms by which this compound induces CYP1A1 expression using rat hepatoma H4IIE cells and V79 cells stably expressing CYP1A1. In H4IIE cells, primaquine caused a time- and dose-dependent increase of CYP1A1 mRNA and protein expression. The transcriptional activation of the CYP1A1 gene by primaquine was strictly XRE-dependent, as shown by transfection of different CYP1A1 pGL3 reporter constructs in H4IIE cells, and the involvement of the AhR was shown by activation of a Gal4-AhR hybrid protein by primaquine in transfected cells. Furthermore, primaquine caused transformation of the cytosolic AhR to a DNA-binding form, in vitro, suggesting that primaquine directly activates the receptor complex. In addition to its action at the transcriptional level, primaquine caused a dose-dependent inhibition of CYP1A1 degradation with an IC(50) of 3.3 , as seen in mammalian V79 cells. This was not due to the lysosomotropic activity of the drug since other lysosomotropic agents were ineffective. Primaquine formed a type II binding spectrum with CYP1A1 and inhibited the CYP1A1-dependent ethoxyresorufin O-deethylase activity in vitro with a K(i) of 1.3 microM, which is close to the IC(50), suggesting that the drug protects CYP1A1 from degradation by binding at the active site. It is concluded that CYP1A1 is regulated by primaquine both on the transcriptional as well as on a post-translational level.

Phylogenetic relationships within the Gentianales based on NDHF and RBCL sequences, with particular reference to the Loganiaceae.

Phylogenetic relationships in the Gentianales with focus on Loganiaceae sensu lato are evaluated using parsimony analyses of nucleotide sequence data from the plastid genes rbcL and ndhF. Inter- and intrafamilial relationships in the Gentianales, which consist of the families Apocynaceae (including Asclepiadaceae), Gelsemiaceae, Gentianaceae, Loganiaceae, and Rubiaceae, are studied and receive increased support from the combination of rbcL and ndhF data, which indicate that the family Rubiaceae forms the sister group to the successively nested Gentianaceae, Apocynaceae, and Loganiaceae, all of which are well supported. The family Gelsemiaceae forms a distinct, supported group sister to Apocynaceae. The Loganiaceae sensu stricto form a strongly supported group consisting of 13 genera: Antonia, Bonyunia, Gardneria, Geniostoma, Labordia, Logania, Mitrasacme, Mitreola, Neuburgia, Norrisia, Spigelia, Strychnos, and Usteria. These genera form two well-supported lineages. Several members of Loganiaceae sensu Leeuwenberg and Leenhouts, i.e., Androya, Peltanthera, Plocosperma, Polypremum, and Sanango are clearly not members of the Gentianales. The earlier exclusion of Buddlejaceae (including Buddleja, Emorya, Gomphostigma, and Nicodemia) as well as the reclassification of the genera Nuxia and Retzia to Stilbaceae of the Lamiales are all well supported.

Effect of intra-aortic magnesium on renal function during and after abdominal aortic surgery: a pilot study.

BACKGROUND: Infrarenal aortic cross-clamping causes renal vasoconstriction. Magnesium may protect against renal deterioration through its vasodilatory properties. METHODS: Thirty patients with normal preoperative renal function undergoing infrarenal aortic cross-clamping for elective aortic surgery received magnesium (4 mmol) or saline into the aorta immediately after aortic cross-clamping and again just before unclamping in a double-blind fashion. Pulmonary artery occlusion pressure was maintained 215 mmHg. Five patients with magnesium were excluded due to need for intravenous nitroglycerine because of myocardial ischaemia during the study. RESULTS: Postoperative creatinine clearance remained unchanged in both groups. Urinary N-acetyl-beta-D-glucosaminidase excretion increased before and decreased after aortic cross-clamping in both groups. The concentrations of glutathione peroxidase in serum were identical between the two groups. CONCLUSIONS: These data indicate that intra-aortic magnesium had no effect on renal function during or after aortic cross-clamping.

Changes in heart rate variability in elderly patients undergoing major noncardiac surgery under spinal or general anesthesia.

BACKGROUND AND OBJECTIVES: Heart rate variability (HRV), widely used as an indicator of activity of the autonomic nervous system, has been reported to decrease during and after both spinal and general anesthesia in patients without cardiovascular disease. We evaluated the changes in HRV bands in 40 patients with a high risk of ischemic heart disease. METHODS: The patients were randomly assigned to receive either spinal (SA) or general anesthesia (GA) for elective total hip arthroplasty or peripheral vascular surgery. Anesthetic techniques and perioperative fluid administration were standardized. Holter monitoring was started preoperatively and continued until the third postoperative day. Three HRV frequency bands were analyzed. RESULTS: A significant decrease was seen in very low frequency (VLF) and low frequency (LF) bands during GA but not during SA. Also the LF/high frequency (HF) ratio decreased during GA but not during SA. A decrease in all HRV frequency bands was seen after both types of anesthesia. None of the frequency bands returned back to the preoperative level during the 3-day trial. Postoperatively circadian variation was found only in the VLF band after SA. CONCLUSIONS: The sympathovagal balance (LF/HF) is more stable during SA than during GA in patients with a high risk of ischemic heart disease. The postoperative decrease in HRV bands, however, is independent of the anesthetic technique.

Structural and mechanistic aspects of transcriptional induction of cytochrome P450 1A1 by benzimidazole derivatives in rat hepatoma H4IIE cells.

The effect of several structurally different benzimidazole compounds on CYP1A1 expression at the transcriptional, mRNA and protein levels was investigated in the rat hepatoma H4IIE cell line. Omeprazole, thiabendazole, carbendazim, 2-mercaptobenzimidazole and 2-mercapto-5-methoxybenzimidazole caused a dose-dependent increase in CYP1A1 protein levels that reached maximum effect at 250 microm, as measured by Western blot. In addition, hydroxyomeprazole, 2-aminobenzimidazole and 2-mercapto-5-nitro-benzimidazole caused a notable increase in CYP1A1 protein expression, whereas 5-O-desmethylomeprazole, 2-hydroxybenzimidazole, 2-benzimidazole propionic acid and 5-benzimidazole carboxylic acid were ineffective. Thus, benzimidazole substituted with a thiol or an amino group in the 2-position were active inducers. Northern blot analysis confirmed an extensive increase of CYP1A1 mRNA induced by omeprazole and 2-mercapto-5-methoxybenzimidazole which was 32% and 49% of maximal induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) respectively, whereas thiabendazole and carbendazim showed approximately 15% increase as compared to TCDD. Transient transfection of H4IIE cells, with a XRE-pGL3 reporter gene construct revealed a 2.3-4.3-fold induction by carbendazim, thiabendazole, and 2-mercapto-5-methoxybenzimidazole as compared to a 3.3- and 23-fold induction by omeprazole and TCDD, respectively. Thus, these data indicate that the benzimidazoles utilize the aryl hydrocarbon receptor-arnt-XRE-mediated signal-transduction pathway for induction of the CYP1A1 gene.

Factors associated with post-operative myocardial ischaemia in elderly patients undergoing major non-cardiac surgery.

Forty patients (> 65 years) undergoing hip arthroplasty or peripheral vascular surgery both associated with high risk for post-operative myocardial ischaemia were randomized to receive either spinal or general anaesthesia. Ambulatory ECG recording (Holter) until the third post-operative morning, a daily 12-lead ECG and serum creatine kinase and troponine concentraItions were obtained. The number of ischaemic episodes, total duration of ischaemia and ischaemic minutes per hour were noted for each patient peri-operatively. Sixteen of the patients (40%) had post-operative myocardial ischaemia. An intra-operative increase in the plasma concentration of norepinephrine but not epinephrine was detected in the patients who later developed post-operative myocardial ischaemia. The increase in plasma norepinIephrine concentrations correlated with the decrease in core temperature. The type of anaesthesia had no effect on the incidence of myocardial ischaemia during or after surgery. Our results suggests that intra-operatively decreased core temperature and the increase in plasma concentration of norepinephrine probably caused peripheral vasoconstriction leading to latent cardiac dysfunction. These events should be avoided in the patients at risk of post-operative cardiac ischaemia.

Effect of temperature of insufflated CO2 during and after prolonged laparoscopic surgery.

BACKGROUND: Pneumoperitoneum with room temperature carbon dioxide (CO2) has been shown to decrease core temperature and urine output. METHODS: The effect of 37 degrees C (warm) and room temperature (cool) CO2 pneumoperitoneum on core temperature, urine output, and central hemodynamics was compared in 26 randomized patients undergoing prolonged laparoscopic surgery (>90 min). RESULTS: The core temperature (p < 0.05) and cardiac index (p < 0.05) were significantly higher after warm than after cool pneumoperitoneum. Urine output was significantly higher during warm (2.3 +/- 1.6 ml/kg/h) than during cool (0.9 +/- 0.7 ml/kg/h) insufflation (p < 0. 05). Two of 13 patients with warm and 11 of 13 patients with cool pneumoperitoneum needed mannitol to maintain adequate diuresis (p < 0.05). CONCLUSIONS: Warm insufflation probably causes a local vasodilation in the kidneys and may be beneficial to patients with borderline renal function.

Comparison of epidural morphine and oxycodone for pain after abdominal surgery.

STUDY OBJECTIVE: To compare the efficacy and side effects of epidural morphine and oxycodone for pain following major abdominal surgery. DESIGN: Randomized, double-blind study. SETTING: 4th Department of Surgery, Helsinki University Central Hospital. PATIENTS: 44 adult ASA physical status I, II, and III patients scheduled for elective major abdominal surgery. INTERVENTIONS: Thirty-three patients were allocated randomly to one of two epidural groups and 11 patients received oxycodone intravenously (IV). The two epidural groups received either morphine (bolus 0.015 mg/kg followed by an infusion 0.003 mg/kg/hr) or oxycodone (bolus 0.15 mg/kg followed by an infusion 0.03 mg/kg/hr) before induction of standardized anesthesia and for 24 hours thereafter. A third group of patients was given the same dose of IV oxycodone as in the epidural group, serving as an open control group for epidural oxycodone. MEASUREMENTS AND MAIN RESULTS: Blood samples were drawn for plasma opioid concentrations. Postoperatively, pain (at rest and during coughing), nausea, pruritus, sedation, respiratory rate, and hemodynamics were recorded until the end of the infusions. The epidural dose ratio between morphine and oxycodone was 1:8.4 to 9.8 to provide similar analgesia. Side effects occurred similarly in the three groups. Mild respiratory depression was seen in all groups, especially in the IV oxycodone group. In all groups, hemodynamic variables remained within normal limits. CONCLUSIONS: In the dosages reported, oxycodone can be used epidurally for acute post-operative pain. The analgesic effect was as good as that of epidural morphine.

Signal transduction-mediated activation of the aryl hydrocarbon receptor in rat hepatoma H4IIE cells.

We have investigated mechanisms of omeprazole (OME)-mediated induction of CYP1A1 and CYP3A, using the rat hepatoma H4IIE cell line, in comparison with mechanisms exerted by traditional aryl hydrocarbon receptor (AhR) ligands such as benso(a)pyrene (B(a)P) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). OME did not bind specifically to AhR, and it could not activate the AhR complex in rat cytosol to a xenobiotic-responsive element (XRE)-binding form in vitro. Genistein, a tyrosine kinase inhibitor, and daidzein, an inhibitor of casein kinase II, efficiently inhibited OME-mediated but not B(a)P- or TCDD-mediated induction of CYP1A1, as monitored at the transcriptional, mRNA, and protein levels as well as by analysis of activation of XRE-luciferase reporter constructs transfected into H4IIE cells. The protease inhibitor Nalpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and lavendustin A also had similar OME-specific effects. In addition, insulin pretreatment caused an almost complete inhibition of OME-dependent CYP1A1 induction but only partially affected TCDD and B(a)P-mediated induction of CYP1A1. Staurosporine, an inhibitor of protein kinase C, impaired the induction by both B(a)P and OME. OME caused an approximately 2-fold increase in the level of CYP3A expression, but all inhibitors used were ineffective in preventing this induction. Gel shift analysis with radiolabeled XRE and specific peptide antibodies toward AhR and aryl hydrocarbon receptor nuclear translocator protein (Arnt) revealed an OME-mediated translocation of the AhR.Arnt complex into the nuclei. Genistein inhibited the specific nuclear XRE binding caused by OME, but it potentiated the formation of the TCDD-induced XRE.AhR complex. Although daidzein was able to effectively inhibit the OME-stimulated CYP1A1 gene transcription, it did not influence the OME-dependent AhR.XRE complex formation. The data are consistent with a mechanism for OME-mediated induction of CYP1A1 that involves activation of the AhR complex via intracellular signal transduction systems and that is distinct from induction mediated by AhR ligands.

Cardiac failure aggravated by timolol eye drops: preoperative improvement by changing to pilocarpine.

A 73-year-old woman with cardiac dysfunction had several episodes of severe bradycardia and pulmonary oedema when waiting for peripheral vascular surgery. She used timolol eye drops for primary open-angle glaucoma. The first episode of pulmonary oedema occurred two weeks prior to and the second on the day before the planned surgery. There were another two episodes of pulmonary oedema before she was transferred to the Department of Internal Medicine where she had a further two episodes of cardiac failure. After changing timolol to pilocarpine eye drops, the patient's condition was stabilized, and two weeks later surgery and postoperative recovery were uneventful.