MRI during radiotherapy of glioblastoma : Does MRI allow for prognostic stratification?

AIM: To evaluate the role of magnetic resonance imaging (MRI) as a predictor for the clinical course in patients with glioblastoma. PATIENTS AND METHODS: In 64 patients with glioblastoma undergoing (chemo)radiotherapy MRI studies were obtained before radiation, after 30 gray (Gy), after 60 Gy and during follow-up. MRI findings were assigned to categories: definite progression, questionable progression, no change. Patients were followed clinically. RESULTS: At 30 Gy, 23 of 64 patients (36 %) demonstrated definite (dp; n = 15) or questionable (qp; n = 8) progression; in 41/64 (64 %) no change was found compared with preradiation MRI. After radiotherapy at 60 Gy, 26 of 64 (41 %) patients showed dp (n = 18) or qp (n = 8). In 2 cases with qp at the 30 Gy MRI, progress was unquestionable in the 60 Gy MRI study. In the 64 patients, 5 of the 60 Gy MRIs showed dp/qp after being classified as no change at the 30 Gy MRI, 2 of the 30 Gy MRIs showed qp, while the 60 Gy MRI showed tumour regression and 3 fulfilled the criteria for pseudoprogression during ongoing radiotherapy. The 30 Gy study allowed for prognostic stratification: dp/qp compared to stable patients showed median survival of 10.5 versus 20 months. CONCLUSION: MR follow-up after 30 Gy in patients undergoing (chemo)radiotherapy for glioblastoma allows prognostic appraisal. Pseudoprogression has to be taken into account, though rare in our setting. Based on these findings, early discussion of treatment modification is possible.

[Change of Taste during and after IM- /IG-Radiotherapy for Head and Neck Cancer Patients]. / Veränderungen des Schmeckvermögens durch IM-/IG-Strahlentherapie bei Kopf-Hals-Tumorpatienten.

OBJECTIVE: Taste dysfunction is a common side effect during irradiation of head and neck. Our aim was to determine the time-dependent course and a possible dependency of this side effect to the radiation-dose during irradiation with helical tomotherapy. PATIENTS AND METHODS: 31 patients with malignant tumours in the region of head and neck received an IG-/IM-radiotherapy (helical tomotherapy).The median total dose was 63 Gy (range 30-66 Gy). For all patients the subjective taste dysfunction was documented and correlated to the median (D50) tongue dose. RESULTS: A subjective taste dysfunction was registered by the patients themselves after 9 BT (days of radiotherapy) (median). This correlates to a mean dose (D50) of 15.3 Gy (back third of tongue (back ZD)), 11.3 Gy (middle ZD), 8.2 Gy (front ZD). A subjective ageusia occurred after 15 BT (median) (28.9 Gy (back ZD), 22.2 Gy (middle ZD), 17.7 Gy (front ZD)). A starting recovery was registered by 77% of the patients in the first 6-8 weeks after the end of radiotherapy. CONCLUSION: The time-dependent course of taste dysfunction during radiotherapy and the following recovery is predictable. A dependency of taste dysfunction to radiation-dose exists. Based on the collected data a targeted dose reduction to the tongue with a view to minimize the taste dysfunction is thinkable and aim of further studies.

Quality of patient positioning during cerebral tomotherapy irradiation using different mask systems.

BACKGROUND AND PURPOSE: Patient immobilization during brain tumor radiotherapy is achieved by employing different mask systems. Two innovative mask systems were developed to minimize the problems of claustrophobic patients. Our aim was to evaluate whether the quality of patient immobilization using the new mask systems was equivalent to the standard mask system currently in use. MATERIAL AND METHODS: Thirty-three patients with cerebral target volumes were irradiated using the Hi-Art II tomotherapy system between 2010 and 2012. Each group of 11 patients was fitted with one of the two new mask systems (Crystal® or Open Face® mask, Orfit) or the standard three-point mask (Raycast®-HP, Orfit) and a total of 557 radiotherapy fractions were evaluated. After positioning was checked by MV-CT, the necessary table adjustments were noted. Data were analyzed by comparing the groups, and safety margins were calculated for nonimage-guided irradiation. RESULTS: The mean values of the table adjustments were: (a) lateral (mm): - 0.22 (mask 1, standard deviation (σ): 2.15); 1.1 (mask 2, σ: 2.4); - 0.64 (mask 3, σ: 2.9); (b) longitudinal (mm): - 1 (mask 1, σ: 2.57); - 0.5 (mask 2, σ: 4.7); - 1.22 (mask 3, σ: 2.52); (c) vertical (mm): 0.62 (mask 1, σ: 0.63); 1.2 (mask 2, σ: 1.0); 0.57 (mask 3, σ: 0.28); (d) roll: 0.35° (mask 1, σ: 0.75); 0° (mask 2, σ: 0.8); 0.02° (mask 3, σ: 1.12). The outcomes suggest necessary safety margins of 5.49-7.38 mm (lateral), 5.4-6.56 mm (longitudinal), 0.82-3.9 mm (vertical), and 1.93-4.5° (roll). There were no significant differences between the groups. CONCLUSIONS: The new mask systems improve patient comfort while providing consistent patient positioning.

[Soft tissue tumors of the head and neck region]. / Weichteiltumoren des Kopf-Hals-Bereichs.

BACKGROUND: The incidence of soft tissue tumors of the head and neck region is low: 300 and 3 in 100,000 for benign and malignant tumors, respectively. However, sarcomas particularly show a wide variety of different histological subtypes. This article provides an overview of the soft tissue tumors of the head and neck region treated in the authors' institution. MATERIAL AND METHODS: This is a retrospective study including 106 patients treated between 2002 and 2010 due to a soft tissue tumor. Tumor- and patient-specific data were collected (benign/malignant tumor, location, TNM classification, therapy, R classification, grade). RESULTS: In total, 77 benign tumors, 5 of intermediate benign/malignant nature and 24 sarcomas (with 7 different subtypes) were identified. Whereas the benign and intermediate tumors were treated by surgical removal, in 21 of the 24 sarcomas, treatment comprised a multimodal therapy regimen including radio- and/or chemotherapy. CONCLUSION: Whereas benign tumors can be successfully treated by surgical resection, there is no uniform therapy regimen for sarcomas due to the variety of different histological subtypes. Only case-specific interdisciplinary disease management can offer good perspectives for therapeutic success.

[Treatment results of nasopharyngeal carcinoma in adults]. / Ergebnisse beim Nasopharynxkarzinom im Erwachsenenalter.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a rare tumor entity in Germany in contrast to endemic countries in Asia or Africa. This retrospective study investigated patient characteristics and prognostic factors with respect to different NPC treatment strategies. PATIENTS AND METHODS: A total of 63 NPC patients treated during the period 1990-2009 at the University Hospital Bonn, Germany, were included. RESULTS: The median age of the patients was 56.4 years, the male:female ratio was 3.2:1, 23.8% were in Union Internationale Contre le Cancer (UICC) stage I/II and 76.2% were in stage III/IV. Most of the carcinomas were WHO type III (57.1%), followed by World Health Organization (WHO) type II (33.3%) and at last WHO type I (9.6%). The 5-year overall survival rate after concomitant chemoradiotherapy (RCT) was 75% and after radiotherapy (RT) 60%. The mortality rate increased by 3.5 times with each increase in T-stage (p ≤ 0.047). The recurrence rate (RR) after RCT was 34% and after RT alone 68% (p ≤ 0.04). Tumor ablation increased the RR significantly (p ≤ 0.047). CONCLUSION: Combined chemotherapy and RT is an effective treatment of NPC disease and clearly superior to RT alone. Tumor ablation before RCT/RT worsens the prognosis and is now obsolete.

Gamma-amino butyric acid inhibits the nicotine-imposed stimulatory challenge in xenograft models of non-small cell lung carcinoma.

Non-small cell lung carcinoma (NSCLC) is the leading type of lung cancer; smoking is a documented risk factor. Nicotinic acetylcholine receptor (nAChR)-mediated intracellular signaling in response to nicotine has recently been implicated in the growth regulation of NSCLC. In the current study nude mice carrying xenografts of the human lung NSCLC cell lines NCI-H322 or NCI-H441 were used as animal models. Nicotine administration and gamma aminobutyric acid (GABA) treatment lasted for 30 days. Catecholamines, cortisol, GABA, and cAMP were analyzed in blood and tumor tissues by immunoassays. Expression of nicotinic receptors and effector proteins in the xenografts was assessed by Western blotting. Our data indicate that nicotine stimulated the growth of NSCLC xenografts via modulation of nAChR upregulation and activation of cAMP signaling. The nicotine-treated group showed an enhanced level of stress neurotransmitters and second messenger cAMP in serum, blood cellular fraction, and xenograft tissues. Activation of critical proteins in the oncogenic pathway, including CREB, ERK, Akt, and Src, and upregulation of α-4 and α-7 subunits of nAChR provided mechanistic insight for the observed stimulatory effect of nicotine. Interestingly, GABA, being an antagonist to cAMP signaling, showed a promising intervention by reversing the stimulatory effect of nicotine on cancer growth and all signaling pathways. GABA has potential to lower the risk of NSCLC among smokers and could be used to enhance the clinical outcome of standard cancer intervention strategies.

NNK activates ERK1/2 and CREB/ATF-1 via beta-1-AR and EGFR signaling in human lung adenocarcinoma and small airway epithelial cells.

We have shown that the tobacco nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is an agonist for -adrenergic receptors (beta-ARs) and increased DNA synthesis of human lung adenocarcinoma cells with features of bronchiolar Clara cells by binding to these receptors. Using a cell line derived from a human pulmonary adenocarcinoma with Clara cell phenotype (PACC) and immortalized human small airway epithelial cells (HPLD1), the putative cells of origin of this cancer type, our current studies have analyzed signaling initiated by binding of NNK to the beta 1-AR. NNK upregulated ERK1/2 and CREB/ATF-1 phosphorylation in a PKA-dependent manner in both cell lines. This response was further increased by transient overexpression of the beta 1-AR. Pre-exposure of cells to the selective beta 1-AR antagonist, atenolol, attenuated the stimulatory effects of NNK, suggesting the latter upregulated ERK1/2 and CREB/ATF-1 via this receptor. In vivo labeling and immunoprecipitation assays revealed that NNK phosphorylated the epidermal growth factor receptor (EGFR) at tyrosine residues, 991, 1068 and 1173, an effect inhibited by atenolol. The inhibitor of EGFR-specific tyrosine kinases, AG1478, reduced NNK ability to stimulate ERK1/2 and CREB/ATF-1. Genomic analysis of the exons 18-21 of the EGFR genes showed that no mutations were present in either gene. Collectively, our data provide evidence, for the first time, that NNK targets ERK1/2 and CREB/ATF-1 proteins via dual signaling involving beta 1-AR and EGFR pathways in PACCs and their putative cells of origin.

PKA-dependent growth stimulation of cells derived from human pulmonary adenocarcinoma and small airway epithelium by dexamethasone.

Smoking is a risk factor for lung cancer, chronic obstructive pulmonary disease, chronic bronchitis and asthma. The chronic lung diseases are also a predisposing factor for the development of lung cancer. Glucocorticoids are used for the management of chronic lung diseases because of their anti-inflammatory activity. These drugs also have anti-tumourigenic effects in mouse models of lung cancer. Glucocorticoids are frequently used as co-treatment with cancer therapy. Using the human pulmonary adenocarcinoma (PAC) cell line NCI-H322 with features of bronchiolar Clara cells, and immortalised human small airway epithelial cells, our data show that the glucocorticoid dexamethasone increased cell proliferation in MTT assays in a PKA-dependent manner. Dexamethasone significantly increased intracellular cAMP in direct immunoassays. Immunoblot analysis revealed increased phosphorylation of ERK1/2 and of the transcription factor CREB in response to dexamethasone. These data suggest that glucocorticoids could have tumour promoting activity on a sub-set of human PAC.

Expression of ABC-1 transporter is elevated in human glioma cells under irradiation and temozolomide treatment.

OBJECTIVE: Chemo-therapeutic treatment of glioma patients has minor success. Little is known about mechanisms of a pronounced resistance of gliomas towards actual therapies, yet. ABC-1 belongs to the group of transporters known to be involved in the export of hydrophobic substances and vascular regulation. This study investigates an effect of both temozolomide (TMZ) treatment and/or irradiation on the expression of the ABC-1 transporter in human U87-MG glioma cells. MATERIAL AND METHODS: In parallel experiments U87-MG cells underwent either irradiation (RT), chemo-treatment (CT) using TMZ, and combined chemo/radiation-treatment (CT/RT). After each treatment the cells were incubated either 2 or 24 hours at 37 degrees C and counted before protein analysis using Western-Blot technique. RESULTS AND CONCLUSIONS: An exponential growth of cellular density was observed for both untreated and irradiated cells being, however, about 2-times slower in irradiated compared to untreated cells. In contrast the density increase of chemo-treated cells as well as that of cells, which underwent the combined CT/RT treatment was of linear nature. ABC-1 expression was detected in untreated as well as treated cells. Increasing cell density and all kinds of treatment resulted in a considerably enhanced ABC-1 expression. CT treatment resulted in highly up-regulated ABC-1 expression especially in non-confluent cultures compared to untreated cells. Irradiation had a comparable or even higher inducible effect on the ABC-1 expression rates depending, however, on cell density. The highest expression rates were observed in cultures with high cellular density 2 hours after application of the combined treatment. Strong up-regulation of ABC-1 expression under both irradiation and chemo-treatment might be a clue to multidrug and irradiation cross-resistance mechanisms of malignant glioma cells converting the ABC-1 transporter into an attractive pharmacological target for a clinical breakthrough in the therapy of malignant gliomas.

Magnetic resonance imaging analysis of anterior and posterior eye segment displacement during ocular gaze shifts.

PURPOSE: To determine the relationship between movements of the posterior and anterior eye segments during arbitrary gaze shifts and to obtain information for monitoring fixation during radiotherapy for ocular diseases. METHODS: We examined eye movements of ten emmetropic volunteers in a 1.5 T magnetic resonance system. Using a T2-weighted ultrafast turbo-spin echo sequence (UTSE), the eyes were examined within 21 seconds. Sagittal and transversal eye slices were obtained in five passages in five gaze directions (straight ahead, 15 degrees above, 15 degrees below, 15 degrees right and 15 degrees left of the primary position). Displacement of the posterior eye segment was analyzed in relation to the movement of the anterior segment in all directions. RESULTS: The relationship between the movements of the anterior and posterior eye segment was 1:0.8 (+/- 0.06 SD) during horizontal gaze shifts and 1:1.16 (+/- 0.11 SD) during vertical gaze shifts. CONCLUSIONS: Magnetic resonance imaging showed that the relationship between anterior and posterior eye segments was different during horizontal and vertical eye movements, indicating the presence of more than one center of rotation. Compared to the anterior eye segment, there was less displacement of the posterior eye segment during horizontal eye movements and more displacement during vertical eye movements.

Malignant thymoma: current status of classification and multimodality treatment.

Classification, understanding of the pathophysiology, and treatment options of thymoma have changed during recent years. It is hoped that novel strategies will lead to a survival benefit in these patients. It has become clear that patients with thymoma are best treated with multimodality therapy. In this review, a pathologist, an immunologist, a surgeon, a radiotherapist, a pneumologist, and oncologists discuss the current status of classification and strategies for the treatment of patients with thymoma.

The cyclooxygenase inhibitor ibuprofen and the FLAP inhibitor MK886 inhibit pancreatic carcinogenesis induced in hamsters by transplacental exposure to ethanol and the tobacco carcinogen NNK.

PURPOSE: Pancreatic cancer is the fourth leading cause of cancer death in men and women. Smoking is a documented risk factor for pancreatic cancer, and the risk is increased in smokers who also consume alcohol. Arachidonic acid (AA)-metabolizing enzymes have been implicated in aggressive clinical behavior of pancreatic cancer while mutations in the Ki- ras gene have been associated with prolonged survival and responsiveness to therapy. Using a hamster model of exocrine pancreatic cancer induced by transplacental exposure to ethanol and the tobacco-carcinogen NNK, we have analyzed these tumors for mutations in the ras and p53 genes and tested the modulating effects of the COX inhibitor, ibuprofen, and the FLAP inhibitor, MK886, on the development of pancreatic cancer in this animal model. METHODS: Hamsters were given 10% ethanol in the drinking water from the fifth to the last day of their pregnancy and a single dose of NNK on the last day. Starting at 4 weeks of age, groups of offspring were given either the COX inhibitor ibuprofen (infant Motrin oral suspension) or the FLAP-inhibitor MK886 (dissolved in carboxymethylcellulose orally) for life while a group of offspring not receiving any treatment served as positive controls. RESULTS: None of the induced pancreatic cancers demonstrated mutations in the Ki-, N-, or H- ras or p53 genes. The development of pancreatic cancer in offspring who had been given ibuprofen or MK886 was reduced by 50% or 30%, respectively. CONCLUSION: In conjunction with the documented over-expression of COX-2 and LOX in human pancreatic cancer, our findings suggest an important role of the AA-cascade in the genesis of this cancer type and indicate that pharmacological or dietary measures that reduce AA-metabolism may be useful for the prevention and clinical management of pancreatic cancer.

Beta-adrenergic and arachidonic acid-mediated growth regulation of human breast cancer cell lines.

Adenocarcinoma of the mammary gland is the leading type of cancer in women. Among these breast cancers those that are estrogen-responsive respond well to existing therapeutic regimens while estrogen non-responsive cancers metastasize widely, demonstrate a high relapse rate, and respond poorly to therapy. Over-expression of the arachidonic acid-metabolizing enzymes cyclooxygenase-2 and lypoxygenases is frequently observed in breast cancer, particularly the non-estrogen-responsive type, suggesting a role of the arachidonic acid (AA) cascade in the growth regulation of these malignancies. Adenocarcinomas of the lungs, pancreas and colon also frequently over-express AA-metabolizing enzymes, and recent evidence suggests that the growth-regulating AA-cascade in these malignancies is under beta-adrenergic control. Our current experiments have therefore tested the hypothesis that in analogy to these findings adenocarcinomas of the breast are also regulated by beta-adrenergic receptors via stimulation of the AA-cascade. Analysis of DNA synthesis by [3H]-thymidine incorporation assays in three estrogen-responsive and three estrogen non-responsive cell lines derived from human breast cancers demonstrated a significant reduction in DNA synthesis by beta-blockers and inhibitors of cyclooxygenase or lipoxygenases in all cell lines. Analysis of AA-release in one of the most responsive cell lines demonstrated a time-dependent increase in AA-release in response to the beta-adrenergic agonist isoproterenol. Analysis by RT-PCR revealed expression of beta2-adrenergic receptors in all cell lines whereas beta1-adrenergic receptors were not found in two of the estrogen non-responsive cell lines. Our data suggest that a significant subset of human breast cancers is under control of beta-adrenergic receptors via stimulation of the AA-cascade. These findings open up novel avenues for the prevention and clinical management of breast cancer, particularly the non-estrogen-responsive types. Moreover, our findings suggest that cardiovascular disease and adenocarcinomas in a variety of organ systems, including the breast may share common risk factors and benefit from similar preventive and treatment strategies.

[1H-MR Spectroscopy of brain tumors in the course of radiation therapy: Use of fast spectroscopic imaging and single-voxel spectroscopy for diagnosing recurrence]. / 1H-MR-Spektroskopie von Hirntumoren im Verlauf der Strahlentherapie: Anwendung von schneller spektroskopischer Bildgebung und Einzelvolumen-MRS in der Rezidivdiagnostik.

PURPOSE: To improve differential diagnosis of residual or recurrent tumor vs. tissue necrosis in the course of radiation therapy of neurosurgically-treated brain tumors by application of fast (1)H-MR spectroscopic imaging in combination with single-voxel spectroscopy (SVS). METHODS: 54 patients after with malignant brain tumor (44 cases of glioblastoma, 10 other high-grade gliomas) were examined post-surgically in a total of 140 proton MRS examinations in the course of radiotherapy and in follow-up controls. Fast SI acquisition was performed as single-slice or double-slice TSI sequence with 32 x 32 phase encodings within 11 or 15 minutes, respectively. SVS with TR/TE 2000/272 ms yielded relative metabolite ratios, and in 15 patients the time courses of the absolute concentrations of brain metabolites were also determined. RESULTS: In the group of 44 patients that could be tracked by MRS until therapy completion, TSI localized in 23 patients a persistent or newly arisen distinct choline accumulation indicating residual or recurrent tumor after radiation therapy. In all these cases MRS diagnosis was confirmed histologically or by short-term follow-up. However, in 6 of 15 patients showing a normal choline pattern in the TSI acquisition, tumor recurrence appeared within three months. SVS provided early recognition of recurrent tumor when detecting characteristic alterations of metabolite concentrations oin therapy follow-up. CONCLUSION: TSI and SVS represent complementary MRS techniques and are able to diagnose tumor recurrence early and unambiguously in cases where focal choline accumulation is detected.

A downstream regulatory element located within the coding sequence mediates autoregulated expression of the yeast fatty acid synthase gene FAS2 by the FAS1 gene product.

The fatty acid synthase genes FAS1 and FAS2 of the yeast Saccharomyces cerevisiae are transcriptionally co-regulated by general transcription factors (such as Reb1, Rap1 and Abf1) and by the phospholipid-specific heterodimeric activator Ino2/Ino4, acting via their corresponding upstream binding sites. Here we provide evidence for a positive autoregulatory influence of FAS1 on FAS2 expression. Even with a constant FAS2 copy number, a 10-fold increase of FAS2 transcript amount was observed in the presence of FAS1 in multi-copy, compared to a fas1 null mutant. Surprisingly, the first 66 nt of the FAS2 coding region turned out as necessary and sufficient for FAS1-dependent gene expression. FAS2-lacZ fusion constructs deleted for this region showed high reporter gene expression even in the absence of FAS1, arguing for a negatively-acting downstream repression site (DRS) responsible for FAS1-dependent expression of FAS2. Our data suggest that the FAS1 gene product, in addition to its catalytic function, is also required for the coordinate biosynthetic control of the yeast FAS complex. An excess of uncomplexed Fas1 may be responsible for the deactivation of an FAS2-specific repressor, acting via the DRS.

Long term results and morbidity of paraaortic compared with paraaortic and iliac adjuvant radiation in clinical stage I seminoma.

BACKGROUND: Radiotherapy is accepted as standard adjuvant treatment for low-stage seminoma and results in excellent survival rates. The optimal radiation field for stage I seminoma, however, is still being discussed. PATIENTS AND METHODS: In a retrospective study we evaluated long-term results concerning survival, relapse-pattern, and acute and chronic toxicity in patients receiving adjuvant radiotherapy of the paraaortic and ipsilateral iliac lymph nodes (hockey-stick, HS) versus radiotherapy of the paraaortic lymph nodes only (PA). From 1979-1997, 129 patients (median age 32 years) in clinical stage I received adjuvant radiotherapy. Eighty-seven patients were treated with 36 Gy to the HS field and 42 patients were treated with a median of 28 Gy to the PA field. RESULTS: With a median follow-up of 7.7 years (HS) and 5.2 years (PA) the relapse rate was 3.4% and 2.4%, respectively. There was no abdominal or pelvic recurrence in either group. Radiotherapy was well tolerated in both groups. No significant difference in acute or chronic toxicity was noted. However, lower gastrointestinal tract toxicities and myelotoxicities appeared less frequent in the PA group. Second malignancies only occurred in the HS group. Overall survival in the HS and PA group was 96.6% and 100%, respectively. No patient died of seminoma. CONCLUSION: With paraaortic radiotherapy only, long-term disease-specific survival was excellent. Decreased risk of acute toxicity and of second malignancies are potential benefits of the reduced radiation field.

4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, a nicotine derivative, induces apoptosis of endothelial cells.

Smoking causes endothelial cell (EC) injury; however, neither the components of cigarette smoke nor the mechanisms responsible for this injury are understood. The nitrosated derivative of nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), has been implicated in the carcinogenic effects of tobacco; however, the effects of NNK on the cardiovascular system are largely unknown. NNK binds to beta1- and beta2-adrenergic receptors. Because beta-adrenergic receptor activation causes arachidonic acid (AA) release and cellular injury, we postulated that NNK causes EC injury by a mechanism that involves beta-adrenergic-mediated release of AA. NNK stimulated [3H]AA release from ECs, and this effect was mediated by both beta1- and beta2-adrenergic receptors because pretreatment with atenolol or ICI 118,551 inhibited the response. NNK also induced EC apoptosis, as measured by terminal deoxyribonucleotide transferase-mediated dUTP nick-end labeling and annexin V staining. NNK-mediated apoptosis was attenuated by pretreatment with atenolol or ICI 118,551. Furthermore, depletion of cellular AA by incubation with eicosapentaenoic acid abolished the apoptotic effect of NNK. These data suggest that NNK causes EC apoptosis by a mechanism that involves beta1- and beta2-adrenergic receptor-mediated release of AA.

Co-expression of beta-adrenergic receptors and cyclooxygenase-2 in pulmonary adenocarcinoma.

Pulmonary adenocarcinoma (PAC) is the leading type of lung cancer and is highly resistant to conventional cancer therapy. A better understanding of the regulatory mechanisms which control the growth of this deadly malignancy are urgently needed to develop more effective cancer intervention strategies. Recent studies have shown that PAC frequently overexpresses cyclooxygenase-2 (COX-2). This enzyme converts arachidonic acid (AA) into several metabolites, some of which have been identified as modulators of mitogenesis and apoptosis. Accordingly, the AA cascade and COX-2 are currently widely studied as potential targets for lung cancer prevention. Recent studies by our research group have shown that cell lines derived from human PACs express beta1- and beta2-adrenergic receptors, which regulate the release of AA and DNA synthesis. Moreover, we have demonstrated that an antagonist for beta-adrenergic receptors or aspirin inhibited the development of experimentally induced PAC in a hamster model. These findings suggest that beta-adrenergic receptors may serve as upstream regulators of AA and COX-2-mediated PAC growth. However, no information is currently available on the expression of beta-adrenergic receptors and its possible correlation with the expression of COX-2 in tissue samples from human PAC, casting some doubt on the significance of these findings in vitro and in an animal model. In the current study, we have therefore analyzed tissue samples of human PACs for the expression of beta1-and beta2-adrenergic receptors as well as COX-2 by reverse transcription polymerase chain reaction (RT-PCR) or immunohistochemistry. Our data show that seven out of eight samples co-expressed COX-2 and one or both of these beta-adrenergic receptors, supporting the experimental evidence for a functional link between these neurotransmitter receptors and the AA cascade in the regulation of human PAC.

The negative regulator Opi1 of phospholipid biosynthesis in yeast contacts the pleiotropic repressor Sin3 and the transcriptional activator Ino2.

Structural genes of phospholipid biosynthesis in the yeast Saccharomyces cerevisiae are transcriptionally co-regulated by ICRE (inositol/choline-responsive element) promoter motifs. Gene activation by an ICRE is mediated by binding of the Ino2/Ino4 transcription factor, whereas repression in the presence of high concentrations of inositol and choline (IC) requires an intact Opi1 repressor. However, the mechanism of specific repression and the functional interplay among these regulators remained unclear from previous work. Using in vivo as well as in vitro interaction assays, we show binding of the pleiotropic repressor Sin3 to the pathway-specific regulator Opi1. The paired amphipathic helix 1 (PAH1) within Sin3 and OSID (Opi1-Sin3 interaction domain) in the N-terminus of Opi1 were mapped as contact sites. The regulatory significance of the Opi1-Sin3 interaction was shown by the obvious deregulation of an ICRE-dependent reporter gene in a sin3 mutant. Opi1 also interacts with a newly identified functional domain of the transcriptional activator Ino2 (RID, repressor interaction domain). These results define the molecular composition of the transcription complex mediating control of ICRE-dependent genes and allow a hypothesis on the flow of regulatory information in response to phospholipid precursors.