Search

Background and Purpose: gamma-Secretase inhibitors (GSIs) block NOTCH receptor cleavage and pathway activation and have been under clinical evaluation for the treatment of malignancies such as T-cell acute lymphoblastic leukaemia (T-ALL). The ability of GSIs to decrease T-ALL cell viability in vitro is a slow process requiring >8 days, however, such treatment durations are not well tolerated in vivo. Here we study GSI's effect on tumour and normal cellular processes to optimize dosing regimens for anti-tumour efficacy.Experimental Approach: Inhibition of the Notch pathway in mouse intestinal epithelium was used to evaluate the effect of GSIs and guide the design of dosing regimens for xenograft models. Serum Abeta(40) and Notch target gene modulation in tumours were used to evaluate the degree and duration of target inhibition. Pharmacokinetic and pharmacodynamic correlations with biochemical, immunohistochemical and profiling data were used to demonstrate GSI mechanism of action in xenograft tumours.Key Results: Three days of >70% Notch pathway inhibition was sufficient to provide an anti-tumour effect and was well tolerated. GSI-induced conversion of mouse epithelial cells to a secretory lineage was time- and dose-dependent. Anti-tumour efficacy was associated with cell cycle arrest and apoptosis that was in part due to Notch-dependent regulation of mitochondrial homeostasis.Conclusions and Implications: Intermittent but potent inhibition of Notch signalling is sufficient for anti-tumour efficacy in these T-ALL models. These findings provide support for the use of GSI in Notch-dependent malignancies and that clinical benefits may be derived from transient but potent inhibition of Notch. [ABSTRACT FROM AUTHOR]

We developed a composite symptom score (CSS) representing disease-related symptom burden over time in patients with malignant pleural mesothelioma (MPM). Longitudinal data were collected from an open-label Phase IIB study in which 239 patients completed the validated MD Anderson Symptom Inventory for MPM (MDASI-MPM). A blinded, independent review committee of external patient-reported outcomes experts advised on MDASI-MPM symptoms to include in the CSS. Through iterative analyses of potential symptom-item combinations, 5 MPM symptoms (pain, fatigue, shortness of breath, muscle weakness, coughing) were selected. The CSS correlated strongly with the full MDASI-MPM symptom set (0.92-0.94) and the Lung Cancer Symptom Scale-Mesothelioma (0.79-0.87) at each co-administration of the scales. The CSS also had good sensitivity to worsening disease and global quality-of-life ratings. The MDASI-MPM CSS can be used as an outcome in MPM clinical trials, including in responder analyses and at the individual patient level. It is brief enough to administer frequently, including electronically, to better capture symptom trajectories during and after a trial and in clinical practice. As a single score, the CSS addresses multiplicity issues that can arise when several symptoms increase due to worsening disease. Our process can be adapted to produce a CSS for other advanced-cancer trials., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Objectives: Anetumab ravtansine is an antibody-drug conjugate consisting of a fully human anti-mesothelin monoclonal antibody conjugated to cytotoxic maytansinoid tubulin inhibitor DM4. Mesothelin is highly expressed in ovarian cancer. This phase Ib study determines the safety, pharmacokinetics, and anti-tumor activity of anetumab ravtansine and pegylated liposomal doxorubicin in mesothelin-expressing platinum-resistant ovarian cancer., Methods: Anetumab ravtansine (5.5 or 6.5 mg/kg) and pegylated liposomal doxorubicin (30 mg/m 2 ) were administered intravenously every 3 weeks to 65 patients with platinum-resistant epithelial ovarian cancer. Mesothelin expression was assessed by central immunohistochemistry. Adverse events, tumor response (RECIST 1.1), and progression-free survival were determined. Biomarker samples were assessed by ELISA and next-generation sequencing., Results: In dose escalation, nine patients received anetumab ravtansine across two doses (5.5 or 6.5 mg/kg). The maximum tolerated dose of anetumab ravtansine was 6.5 mg/kg every 3 weeks and no dose-limiting toxicities were observed. In dose expansion, 56 patients were treated at the maximum tolerated dose. The most common treatment-emergent adverse events of any grade were nausea (47.7%), decreased appetite (43.1%), fatigue (38.5%), diarrhea (32.3%), and corneal disorder (29.2%). In all treated patients the objective response rate was 27.7% (95% CI 17.3% to 40.2%), including one complete (1.5%) and 17 partial responses (26.2%), with median duration of response of 7.6 (95% CI 3.3 to 10.2) months and median progression-free survival of 5.0 (95% CI 3.2 to 6.0) months. In an exploratory analysis of a sub-set of patients (n=19) with high mesothelin expression who received ≤3 prior lines of systemic therapy, the objective response rate was 42.1% (95% CI 20.3% to 66.5%) with a median duration of response of 8.3 (95% CI 4.1 to 12.0) months and median progression-free survival of 8.5 (95% CI 4.0 to 11.4) months., Conclusions: Anetumab ravtansine and pegylated liposomal doxorubicin showed tolerability and promising clinical activity. These results established the dose schedule and the mesothelin-positive target population of this combination for a phase III study in platinum-resistant ovarian cancer., Trial Registration Number: NCT02751918., Competing Interests: Competing interests: ADS: grants from Puma, Immunomedics, Gilead, Synthon, Boehringer-Ingelheim, and Genentech; grants and consulting fees from Merck, Tesaro, Eisai, and R-Pharma USA. IV reports the following conflicts of interest: consulting (2019–2021): Agenus (2021), Aksebio (2021), Amgen (Europe) (2019), AstraZeneca (2019–2022), Bristol Myers Squibb (2021), Clovis Oncology (2019), Carrick Therapeutics (2019), Deciphera Pharmaceuticals (2020–2021), Eisai (2021), Elevar Therapeutics (2020), F. Hoffmann-La Roche (2019–2021), Genmab (2019–2021), GSK (2019–2021), Immunogen (2019–2022), Jazzpharma (2021–2022), Karyopharm (2021), Mersana (2020), Millennium Pharmaceuticals (2019), MSD (2019–2022), Novocure (2020–2022), Novartis (2021), Octimet Oncology NV (2019), Oncoinvent AS (2019–2022), Sanofi (2021), Seagen (2021), Sotio a.s. (2019–2022), Verastem Oncology (2020), Zentalis (2020); contracted research for Oncoinvent AS (2019–2020) and Genmab (2019–2019); and grants (corporate sponsored research) from Amgen (2019–2020) and Roche (2019–2020). AGM: consulting work for Amgen, AstraZeneca, Clovis Oncology, Eisai, F. Hoffmann-La Roche, Genmab, GSK, Immunogen, Mersana, MSD, Novocure, Novartis, Oncoinvent, Seagen, and Sotio; speaker work for AstraZeneca, GSK, Clovis, and Roche; IST funding from Roche and GSK. KNM: advisory boards for AstraZeneca, Aravive, Alkemeres, Clovis, Eisai, EMD/Serono, GSK/Tesaro, Genentech/Roche, Hengrui, Immunogen, INxmed, IMAB, Lilly, Merck, Mereo, Mersana, Myriad, Novartis, OncXerna, OncoNova, Tarveda, Verastem, and VBL Therapeutics; research funding from PTC Therapeutics, Clovis, GSK/Tesaro, Merck, and Verastem; Associate Director for GOG Partners; NRG ovarian chair; and on the GOG Foundation BOD. AO: consultancy fees from AstraZeneca, MSD/Merck, Clovis Oncology, Genmab, Immunogen, PharmaMar, Roche, Tesaro, GSK, Deciphera, Novocure, SUTRO, Akesobio, Mersana Therapeutics, and Shattucklabs; institutional financial interests (research funding) from AbbVie Deutschland, Ability Pharmaceuticals, Advaxis, Aeterna Zentaris, Amgen, SA, Aprea Therapeutics AB, Clovis Oncology, Eisai, F. Hoffmann-La Roche, and Regeneron Pharmaceuticals; travel, accommodations and expenses fees from AstraZeneca, Clovis Oncology, PharmaMar, and Roche. SD: consulting fees for AstraZeneca Pharma, Novartis Pharmaceu, Pfizer Genentech USA, Puma Biotechnology, Amgen, Lilly, AbbVie, Lexicon Pharmaceutical, Eisai, Seagen, Daiichi Sankyo, and Clovis Oncology. LJC: personal fees from Celsion Corporation, Elevar Therapeutics, Myriad Genetics, Rubius Therapeutics, Sorrento Therapeutics, Tarveda Therapeutics, Toray Industries, VBL Therapeutics, OncoNova, Inx Med, and Luzsana Biotechnology; personal fees and other from Corcept Therapeutics; grants and personal fees from GSK and Immunogen; grants from Abbvie, Advaxis, Agenus, Ajinomoto, Array BioPharm, AstraZeneca, Bristol Myers Squibb, Clovis Oncology, Deciphera Parma, Eisai, EMD Serono, ERGOMED Clinical Research, Exelixis, Genentech/Roche, Genmab, Hoffman-LaRoche, Incyte Corporation, Iovance Biotherapeutics, InVentive Health Clinical, Jansen R&D, Leap Therapeutics, Ludwig Institute for Pharmaceuticals, Merck, Mersana Therapeutics, Novocure, Novartis Pharmaceuticals, OncoQuest, PRA International, Regeneron Pharmaceuticals, Seattle Genetics, Serono, Sutro Biopharm, Tesaro (GSK), Arcus Biosciences, Sumitomo Dainippon Pharma Oncolgy, Cerulean Pharma, Karyopharm, BeiGene USA, Ovagene, Pfizer, Pharma Mar USA, Precision Therapeutics, Sanofi, Stemcentrx, TRACON Pharm, and Verastem. BJM: consultant for Acrivon, Adaptimune, Agenus, Akeso Bio, Amgen, Aravive, Bayer, Elevar, EMD Merck, Genmab/Seagen, GOG Foundation, Heng Rui, ImmunoGen, Karyopharm, Iovance, Laekna, Macrogenics, Mersana, Novartis, Novocure, OncoC4, Panavance, Pieris, Pfizer, Puma, Regeneron, Sorrento, VBL, Verastem, and Zentalis; speaker/consultant for AstraZeneca, Clovis, Eisai, Merck, Myriad, Roche/Genentech, and TESARO/GSK; consultant and investigator for Gradalis and US Oncology Research. RLC: grants from Merck, personal fees from GSK, Agenus, Regeneron, and OncoQuest; grants and personal fees from Clovis, Genmab, Roche/Genentech, Janssen, and AstraZeneca. TH: Scientific Advisory Board for AstraZeneca, Aravive, Caris, Clovis, Eisai, Epsilogen, Genentech/Roche, Gradalis, GSK, and Merck. JS and AS: employment and shares: Bayer AG. LK, ASchulz, KK, AW, BC, and CE: employment: Bayer AG., (© IGCS and ESGO 2023. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Background: Few treatment options exist for second-line treatment of malignant pleural mesothelioma. We aimed to assess the antibody-drug conjugate anetumab ravtansine versus vinorelbine in patients with unresectable locally advanced or metastatic disease overexpressing mesothelin who had progressed on first-line platinum-pemetrexed chemotherapy with or without bevacizumab., Methods: In this phase 2, randomised, open-label study, done at 76 hospitals in 14 countries, we enrolled adults (aged ≥18 years) with unresectable locally advanced or metastatic malignant pleural mesothelioma, an Eastern Cooperative Oncology Group performance status of 0-1, and who had progressed on first-line platinum-pemetrexed chemotherapy with or without bevacizumab. Participants were prospectively screened for mesothelin overexpression (defined as 2+ or 3+ mesothelin membrane staining intensity on at least 30% of viable tumour cells by immunohistochemistry) and were randomly assigned (2:1), using an interactive voice and web response system provided by the sponsor, to receive intravenous anetumab ravtansine (6·5 mg/kg on day 1 of each 21-day cycle) or intravenous vinorelbine (30 mg/m 2 once every week) until progression, toxicity, or death. The primary endpoint was progression-free survival according to blinded central radiology review, assessed in the intention-to-treat population, with safety assessed in all participants who received any study treatment. This study is registered with ClinicalTrials.gov, NCT02610140, and is now completed., Findings: Between Dec 3, 2015, and May 31, 2017, 589 patients were enrolled and 248 mesothelin-overexpressing patients were randomly allocated to the two treatment groups (166 patients were randomly assigned to receive anetumab ravtansine and 82 patients were randomly assigned to receive vinorelbine). 105 (63%) of 166 patients treated with anetumab ravtansine (median follow-up 4·0 months [IQR 1·4-5·5]) versus 43 (52%) of 82 patients treated with vinorelbine (3·9 months [1·4-5·4]) had disease progression or died (median progression-free survival 4·3 months [95% CI 4·1-5·2] vs 4·5 months [4·1-5·8]; hazard ratio 1·22 [0·85-1·74]; log-rank p=0·86). The most common grade 3 or worse adverse events were neutropenia (one [1%] of 163 patients for anetumab ravtansine vs 28 [39%] of 72 patients for vinorelbine), pneumonia (seven [4%] vs five [7%]), neutrophil count decrease (two [1%] vs 12 [17%]), and dyspnoea (nine [6%] vs three [4%]). Serious drug-related treatment-emergent adverse events occurred in 12 (7%) patients treated with anetumab ravtansine and 11 (15%) patients treated with vinorelbine. Ten (6%) treatment-emergent deaths occurred with anetumab ravtansine: pneumonia (three [2%]), dyspnoea (two [1%]), sepsis (two [1%]), atrial fibrillation (one [1%]), physical deterioration (one [1%]), hepatic failure (one [1%]), mesothelioma (one [1%]), and renal failure (one [1%]; one patient had 3 events). One (1%) treatment-emergent death occurred in the vinorelbine group (pneumonia)., Interpretation: Anetumab ravtansine showed a manageable safety profile and was not superior to vinorelbine. Further studies are needed to define active treatments in relapsed mesothelin-expressing malignant pleural mesothelioma., Funding: Bayer Healthcare Pharmaceuticals., Competing Interests: Declarations of interests HLK reports grants paid to the University of Chicago to support clinical trials for Aduro, AstraZeneca, Bayer, Blueprint, Bristol Myers Squibb, Deciphera, GlaxoSmithKline, Harpoon, Inhibrx, MacroGenics, Merck, Polaris, Seattle Genetics, and Vivace; consulting fees from Bristol Myers Squibb, Deciphera, Inventiva, Novocure, and Seattle Genetics; payment or honoraria for lectures, presentations, speaker bureaus, manuscript writing, or educational events for AstraZeneca; support for attending meetings, travel, or both from AstraZeneca and Inventiva; participation on a data safety monitoring board or advisory board for Bristol Myers Squibb, Inventiva, and Seattle Genetics; and leadership or fiduciary role on board of directors for the International Mesothelioma Interest Group. SN reports personal payment or honoraria for lectures, presentations, speaker's bureaus, manuscript writing, or educational events from Abbvie, AstraZeneca, BeiGene, Boehringer Ingelheim, Bristol Myers Squibb, Eli Lilly, Pfizer, Pharmamar, Roche, and Takeda; and personal fees for participation on a data safety monitoring board or advisory board from AstraZeneca, Bayer, Daiichi Sanko, Eli Lilly, Pfizer, Roche, Sanofi, and Takeda. AB reports payment or honoraria for lectures, presentations, speaker's bureaus, manuscript writing, or educational events from AstraZeneca, Boehringer Ingelheim, Eli-Lilly, Pfizer, Roche, and Takeda; and support for attending meetings, travel, or both for Boehringer Ingelheim, Merck Sharp and Dohme, and Roche. GLC reports personal consulting fees for their advisory role for Novocure and Zai Lab; personal speaker engagements for Astellas, AstraZeneca, Merck Sharp and Dohme, Novocure, and Zai Lab; and support for attending meetings, travel, or both for Astellas, Novocure, and Merck Sharp and Dohme. JGJVA reports consulting fees for the advisory boards for Amphera, Bayer, Bristol Myers Squibb, Eli-Lilly, and Merck Sharp and Dohme; patents issued on allogenic tumour cell lysate and on combination immuno-oncology, owned by Erasmus MC Cancer Centre; participation on a data safety monitoring board or advisory board for Biocad; unpaid leadership role for the International Association for the Study of Lung Cancer; and stock or stock options for Amphera. JSp reports clinical trial reimbursement to Guy's & St Thomas’ NHS Foundation Trust from Bayer, BergenBio, Boehringer Ingelheim, Bristol Myers Squibb, Genmab, IO Biotech, Lytix, Seattle Genetics, and Starpharma; consulting fees paid to King's College London from Apobec, AVACTA, Bristol Myers Squibb, IO Biotech, and Seattle Genetics; support for attending meetings, travel, or both from Amgen and Janssen; participation on a data safety monitoring board or advisory board for AstraZeneca and Merck; and stock or stock options (co-founder) for Epsilogen. PT reports fees for a symposium presentation from AstraZeneca; and a conference registration fee from AstraZeneca. KN reports personal fees for advisory boards from AbbVie, Amgen, AstraZeneca, Bristol Myers Squibb Belgium, and Roche Belgium; personal fees for lectures from Roche Belgium; and support for attending meetings, travel, or both from AstraZeneca, Merck Sharpe and Dohme, and Pfizer. AG reports payment to Newcastle upon Tyne Hospitals NHS Foundation Trust for the care of patients on a study from Bayer (support for this manuscript). JAB reports institutional payment to the Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital for support of investigator-initiated study from Merck Sharp and Dohme, consulting fees paid to the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital from Bristol Myers Squibb, and payment to the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital for participation on a data safety monitoring board or advisory board for Roche. AS reports consulting fees from ArQule and Sanofi; payment or honoraria for lectures, presentations, speaker's bureaus, manuscript writing, or educational events from Abbvie, Amgen, ArQule, AstraZeneca, Bayer, Bristol Myers Squibb, Celgene, Eisai, Eli-Lilly, Gilead, Merck Sharp and Dohme, Novartis, Pfizer, Roche, Sandoz, Servier, and Takeda; and participation on a data safety monitoring board or advisory board for Bayer, Bristol Myers Squibb, Eisai, Gilead, Merck Sharp and Dohme, Pfizer, and Servier. SC reports payment or honoraria for lectures, presentations, speaker's bureaus, manuscript writing, or educational events from Amphera, Boehringer Ingelheim, Bristol Myers Squibb, Hoffmann La Roche, Merck Sharp and Dohme Oncology, and Pfizer; and support for attending meetings, travel, or both from Amphera, Boehringer Ingelheim, Bristol Myers Squibb, Hoffmann La Roche, Merck Sharp and Dohme Oncology, and Pfizer. JPVM reports consultancy fees from Amgen, AstraZeneca, Boehringer Ingelheim, Pfizer, and Roche; payment and reimbursement of expenses for services and consultancy from Amgen; registration fees from AstraZeneca, Merck Sharp and Dohme Belgium, Bristol Myers Squibb, GlaxoSmithKline, and Roche; and travel and accommodation support from AstraZeneca, Bristol Myers Squibb, Merck Sharp and Dohme Belgium, and Roche. AKN reports personal fees for consulting for clinical trials, quality of life research, and tumour measurement from Bayer (support for this manuscript); grants or contracts to institution from AstraZeneca and Douglas Pharmaceuticals; consulting fees from Atara Biotherapeutics (personal), Pharmabcine (institutional), and Seagen (personal); personal payment or honoraria for lectures, presentations, speaker's bureaus, manuscript writing, or educational events from Bristol Myers Squibb; travel support from AstraZeneca; and participation on a data safety monitoring board or advisory board for Bristol Myers Squibb (personal). GBJ reports personal grants or contracts from Adaptimmune, Amgen, AstraZeneca, Bayer, BeiGene, Bristol Myers Squibb, Celgene, Daiichi Sankyo, Elelixis, Genentech, GlaxoSmithKline, Immatics, Immunocore, Incyte, Kite Pharma, Macrogenics, MedImmune, Merck, Novartis, Regeneron, Repertoire Immune Medicines, Roche, Tmunity Therapeutics, Torque, Verastem, and Xcovery; personal consulting fees for AbbVie, Adicet, Amgen, Ariad, AstraZeneca, Bayer, Bristol Myers Squibb, Celgene, Clovis Oncology, Daiichi Sankyo, Genentech, Gilead, Instil Bio, Janssen, Lilly, Maverick Therapeutics, MedImmune, Merck, Novartis, Roche, Tyme Oncology, Viogin Biotech, and Xcovery; participation on a data safety monitoring board or advisory board for Maverick Therapeutics and Virogin Biotech (personal); and stock or stock options for Virogin Biotech. GBJ also has an immediate family member employed by Johnson and Johnson and Janssen. JSi is an employee of Bayer Healthcare Pharmaceuticals with ownership of stock; and reports unpaid leadership roles for the American Statistical Association, International Society for Clinical Biostatistics, and the Pharmaceutical Industry Working Group on Estimands in Oncology. LK is an external employee of Bayer Healthcare Pharmaceuticals. KK is an employee of Bayer AG Pharma with ownership of stock. AOW is an employee of Bayer AG Pharma. BHC and CE are employees of Bayer Healthcare Pharmaceuticals. RH reports institutional support for the conduct of this study via a Cooperative Research and Development Agreement (CRADA) between Bayer and the Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA. He also has a CRADA with TCR(2) for conduct of clinical studies unrelated to this manuscript. DAF reports grants from Astex Therapeutics, Bayer, Boehringer Ingelheim, Bristol Myers Squibb, and Merck Sharp and Dohme; personal fees from Aldeyra, Atara, Bristol Myers Squibb, Inventiva, Lab21, Roche, RS Oncology, and Targovax; and non-financial support from Bristol Myers Squibb, Clovis, Eli-Lilly, and Roche. All other authors declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Purpose: This phase I study, which to our knowledge is the first-in-human study of this kind, investigates the safety, tolerability, pharmacokinetics, and clinical activity of anetumab ravtansine, an antibody-drug conjugate of anti-mesothelin antibody linked to maytansinoid DM4, in patients with advanced, metastatic, or recurrent solid tumors known to express the tumor-differentiation antigen mesothelin., Patients and Methods: This phase I, open-label, multicenter, dose-escalation and dose-expansion study of anetumab ravtansine enrolled 148 adult patients with multiple solid tumor types. Ten dose-escalation cohorts of patients with advanced or metastatic solid tumors (0.15-7.5 mg/kg) received anetumab ravtansine once every 3 weeks, and 6 expansion cohorts of patients with advanced, recurrent ovarian cancer or malignant mesothelioma received anetumab ravtansine at the maximum tolerated dose once every 3 weeks, 1.8 mg/kg once per week, and 2.2 mg/kg once per week., Results: Forty-five patients were enrolled across the 10 dose-escalation cohorts. The maximum tolerated dose of anetumab ravtansine was 6.5 mg/kg once every 3 weeks or 2.2 mg/kg once per week. Thirty-two patients were enrolled in the 6.5 mg/kg once-every-3-weeks, 35 in the 1.8 mg/kg once-per-week, and 36 in the 2.2 mg/kg once-per-week expansion cohorts. The most common drug-related adverse events were fatigue, nausea, diarrhea, anorexia, vomiting, peripheral sensory neuropathy, and keratitis/keratopathy. There were no drug-related deaths. Anetumab ravtansine pharmacokinetics were dose proportional; the average half-life was 5.5 days. Among 148 patients with mesothelioma or ovarian, pancreatic, non-small-cell lung, and breast cancers, 1 had a complete response, 11 had partial responses, and 66 had stable disease. High levels of tumor mesothelin expression were detected in patients with clinical activity., Conclusion: Anetumab ravtansine exhibited a manageable safety and favorable pharmacokinetic profile with encouraging preliminary antitumor activity in heavily pretreated patients with mesothelin-expressing solid tumors. The results allowed for the determination of recommended doses, schedules, and patient populations for anetumab ravtansine in phase II studies.

Background: Symptom assessment requires psychometrically validated questionnaires that are easy to use, relevant to the disease, and quick to administer. The MD Anderson Symptom Inventory for malignant pleural mesothelioma (MDASI-MPM) was adapted from the general (core) MDASI to assess the severity of cancer-related and treatment-related symptoms specific to patients with this condition. The MDASI-MPM includes the 13 core MDASI symptoms, which are experienced by most cancer patients, and 6 MPM-specific items developed via qualitative interviewing, a method favored by the US Food and Drug Administration for instrument item generation and development. Qualitative interviewing that summarizes the item generation and development for the MDASI-MPM is detailed in a separate report. The psychometric study reported here was the next step in developing the validation dossier for the MDASI-MPM., Results: In this secondary analysis of data from a Phase II trial, 248 patients provided MDASI-MPM data at multiple timepoints during therapy. Over time, fatigue, pain, shortness of breath, feeling of malaise, and muscle weakness were consistently the worst symptoms reported; symptoms interfered most with work and general activity and least with relations with others. Cronbach coefficient alpha values for all MDASI-MPM subscales were at least 0.88 at baseline and 0.91 during treatment, indicating good internal consistency reliability. Intraclass correlations of at least 0.86 for all MDASI-MPM subscales administered a cycle apart (n = 82) were indicative of good test-retest reliability. Correlations between MDASI-MPM subscales and LCSS-Meso scores were at least 0.70 (P < 0.001 for all comparisons). Patients with good performance status had significantly lower scores than did patients with poor performance status (all P < 0.05), supporting evidence for known-group validity and sensitivity. Effect-size differences were 0.69 and higher, indicating medium-to-large effects. The minimally important difference in the MDASI-MPM subscales ranged from 1.0 to 1.5 points on a 0-10 scale., Conclusions: Symptoms specific to a particular cancer, treatment method, or treatment site can be added to the core MDASI to create a tailored, "fit for purpose" instrument. We found the MDASI-MPM to be a valid, reliable, and responsive (sensitive) instrument for assessing the severity of symptoms of patients with MPM and their interference in patients' daily functioning.

Despite the recent advances in the treatment of ovarian cancer, it remains an area of high unmet medical need. Epithelial ovarian cancer is associated with high levels of mesothelin expression, and therefore, mesothelin is an attractive candidate target for the treatment of this disease. Herein, we investigated the antitumor efficacy of the mesothelin-targeting antibody-drug conjugate (ADC) anetumab ravtansine as a novel treatment option for ovarian cancer in monotherapy and in combination with the antitumor agents pegylated liposomal doxorubicin (PLD), carboplatin, copanlisib and bevacizumab. Anetumab ravtansine showed potent antitumor activity as a monotherapy in ovarian cancer models with high mesothelin expression. No activity was seen in mesothelin-negative models. The combination of anetumab ravtansine with PLD showed additive anti-proliferative activity in vitro , which translated into improved therapeutic in vivo efficacy in ovarian cancer cell line- and patient-derived xenograft (PDX) models compared to either agents as a monotherapy. The combination of anetumab ravtansine with the PI3Kα/δ inhibitor copanlisib was additive in the OVCAR-3 and OVCAR-8 cell lines in vitro , showing increased apoptosis in response to the combination treatment. In vivo , the combination of anetumab ravtansine with copanlisib resulted in more potent antitumor activity than either of the treatments alone. Likewise, the combination of anetumab ravtansine with carboplatin or bevacizumab showed improved in vivo efficacy in the ST081 and OVCAR-3 models, respectively. All combinations were well-tolerated. Taken together, these data support the development of anetumab ravtansine for ovarian cancer treatment and highlight its suitability for combination therapy with PLD, carboplatin, copanlisib, or bevacizumab., Competing Interests: CONFLICTS OF INTEREST Conflicts of interest: Quanz, Hagemann, Zitzmann-Kolbe, Stelte-Ludwig, Golfier, Elbi, Mumberg, Ziegelbauer and Schatz are employees of Bayer AG, Cem Elbi is an employee of Bayer US LLS. Mumberg and Ziegelbauer have ownership interest as shares in Bayer AG.

Background: Cells with homologous recombination (HR) deficiency, most notably caused by mutations in the BRCA1 or BRCA2 genes, are sensitive to PARP inhibition. Microsatellite instability (MSI) accounts for 10-15% of colorectal cancer (CRC) and is hypothesized to lead to HR defects due to altered expression of Mre11, a protein required for double strand break (DSB) repair. Indeed, others have reported that PARP inhibition is efficacious in MSI CRC., Methods: Here we examine the response to niraparib, a potent PARP-1/PARP-2 inhibitor currently under clinical evaluation, in MSI versus microsatellite stable (MSS) CRC cell lines in vitro and in vivo. We compiled a large panel of MSI and MSS CRC cell lines and evaluated the anti-proliferative activity of niraparib. In addition to testing single agent cytotoxic activity of niraparib, we also tested irinotecan (or SN-38, the active metabolite of irinotecan) activity alone and in combination with niraparib in vitro and in vivo., Results: In contrast to earlier reports, MSI CRC cell lines were not more sensitive to niraparib than MSS CRC cell lines¸ suggesting that the MSI phenotype does not sensitize CRC cell lines to PARP inhibition. Moreover, even the most sensitive MSI cell lines had niraparib EC50s greater than 10 fold higher than BRCA-deficient cell lines. However, MSI lines were more sensitive to SN-38 than MSS lines, consistent with previous findings. We have also demonstrated that combination of niraparib and irinotecan was more efficacious than either agent alone in both MSI and MSS cell lines both in vitro and in vivo, and that niraparib potentiates the effect of irinotecan regardless of MSI status., Conclusions: Our results support the clinical evaluation of this combination in all CRC patients, regardless of MSI status.

High-content image analysis captures many cellular parameters, but current methods of interpretation of acquired multiple dimensions assume a normal distribution, which is rarely seen in biological data sets. We describe a novel statistically based approach that collapses a set of cellular measurements into a single value, permitting a simplified and unbiased comparison of heterogeneous cellular populations. Differences in multiple cellular responses across two populations are measured using nonparametric Kolmogorov-Smirnov (KS) statistics. This method can be used to study cellular functions, to identify novel target genes and pharmacodynamic biomarkers, and to characterize drug mechanisms of action.

Brahma (BRM) and Brahma-related gene 1 (BRG1) are the ATP-dependent catalytic subunits of the SWI/SNF family of chromatin-remodeling complexes. These complexes are involved in essential processes such as cell cycle, growth, differentiation, and cancer. Using imaging approaches in a cell line that harbors tandem repeats of stably integrated copies of the steroid responsive MMTV-LTR (mouse mammary tumor virus-long terminal repeat), we show that BRG1 and BRM are recruited to the MMTV promoter in a hormone-dependent manner. The recruitment of BRG1 and BRM resulted in chromatin remodeling and decondensation of the MMTV repeat as demonstrated by an increase in the restriction enzyme accessibility and in the size of DNA fluorescence in situ hybridization (FISH) signals. This chromatin remodeling event was concomitant with an increased occupancy of RNA polymerase II and transcriptional activation at the MMTV promoter. The expression of ATPase-deficient forms of BRG1 (BRG1-K-R) or BRM (BRM-K-R) inhibited the remodeling of local and higher order MMTV chromatin structure and resulted in the attenuation of transcription. In vivo photobleaching experiments provided direct evidence that BRG1, BRG1-K-R, and BRM chromatin-remodeling complexes have distinct kinetic properties on the MMTV array, and they dynamically associate with and dissociate from MMTV chromatin in a manner dependent on hormone and a functional ATPase domain. Our data provide a kinetic and mechanistic basis for the BRG1 and BRM chromatin-remodeling complexes in regulating gene expression at a steroid hormone inducible promoter.

We have identified a critical role for amplified FGFR2 in gastric cancer cell proliferation and survival. In a panel of gastric cancer cell lines, fibroblast growth factor receptor 2 (FGFR2) was overexpressed and tyrosine phosphorylated selectively in FGFR2-amplified cell lines KatoIII, Snu16, and OCUM-2M. FGFR2 kinase inhibition by a specific small-molecule inhibitor resulted in selective and potent growth inhibition in FGFR2-amplified cell lines, resulting in growth arrest in KatoIII cells and prominent induction of apoptosis in both Snu16 and OCUM-2M cells. FGFR2-amplified cell lines also contained elevated phosphotyrosine in EGFR, Her2, and Erbb3, but the elevated phosphorylation in EGFR could not be inhibited by gefitinib or erlotinib. We show that the elevated EGFR, Her2, and Erbb3 phosphotyrosine is dependent on FGFR2, revealing EGFR family kinases to be downstream targets of amplified FGFR2. Moreover, shRNA to Erbb3 resulted in a loss of proliferation, confirming a functional role for the activated EGFR signaling pathway. These results reveal that both the FGFR2 and EGFR family signaling pathways are activated in FGFR2-amplified gastric cancer cell lines to drive cell proliferation and survival. Inhibitors of FGFR2 or Erbb3 signaling may have therapeutic efficacy in the subset of gastric cancers containing FGFR2 amplification.

IGF binding protein (IGFBP)-3 can induce apoptosis in human prostate cancer cells directly without sequestering IGF-I and -II. The molecular mechanisms responsible for the IGF-independent actions of IGFBP-3 remain unclear. IGFBP-3, a secreted protein, can be internalized and translocate to the nucleus. It binds to the nuclear retinoid X receptor (RXR)-alpha. Binding to RXR-alpha has been proposed to be required for IGFBP-3 to induce apoptosis. The present study tests this hypothesis in the PC-3 human prostate cancer cell line. PC-3 cells express RXR-alpha, and apoptosis is induced by incubation with RXR-specific ligand. A COOH-terminal region in IGFBP-3 (residues 215-232) contains a nuclear localization signal, and binding domains for RXR-alpha and heparin (HBD). Different combinations of the 11 amino acids in this region that differ from IGFBP-1, a related IGFBP, which does not localize to the nucleus or bind RXR-alpha, were mutated to the IGFBP-1 sequence. By confocal imaging, mutation of residues 228-KGRKR-232 in nonsecreted IGFBP-3 diminished its nuclear localization. IGFBP-3 binding to glutathione S-transferase-RXR-alpha only was lost when all 11 sites were mutated (HBD-11m-IGFBP-3). Expressed nuclear RXR-alpha did not transport cytoplasmic IGFBP-3 nuclear localization signal mutants that can bind RXR-alpha to the nucleus even after treatment with RXR ligand. Expressed HBD-11m-IGFBP-3 still induced apoptosis in PC-3 cells in an IGF-independent manner as determined by flow cytometric analysis of Annexin V staining. We conclude that in PC-3 cells, RXR-alpha is not required for the nuclear translocation of IGFBP-3 and that IGFBP-3 can induce apoptosis in human prostate cancer cells without binding RXR-alpha.

Ligand binding to the glucocorticoid receptor (GR) results in receptor binding to glucocorticoid response elements (GREs) and the formation of transcriptional regulatory complexes. Equally important, these complexes are continuously disassembled, with active processes driving GR off GREs. We found that co-chaperone p23-dependent disruption of GR-driven transcription depended on the ligand binding domain (LBD). Next, we examined the importance of the LBD and of ligand dissociation in GR-GRE dissociation in living cells. We showed in fluorescence recovery after photobleaching studies that dissociation of GR from GREs is faster in the absence of the LBD. Furthermore, GR interaction with a target promoter revealed ligand-specific exchange rates. However, using covalently binding ligands, we demonstrated that ligand dissociation is not required for receptor dissociation from GREs. Overall, these studies showed that activities impinging on the LBD regulate GR exchange with GREs but that the dissociation of GR from GREs is independent from ligand dissociation.

Androgens have key roles in normal physiology and in male sexual differentiation as well as in pathological conditions such as prostate cancer. Androgens act through the androgen receptor (AR), which is a ligand-modulated transcription factor. Antiandrogens block AR function and are widely used in disease states, but little is known about their mechanism of action in vivo. Here, we describe a rapid differential interaction of AR with target genomic sites in living cells in the presence of agonists which coincides with the recruitment of BRM ATPase complex and chromatin remodeling, resulting in transcriptional activation. In contrast, the interaction of antagonist-bound or mutant AR with its target was found to be kinetically different: it was dramatically faster, occurred without chromatin remodeling, and resulted in the lack of transcriptional inhibition. Fluorescent resonance energy transfer analysis of wild-type AR and a transcriptionally compromised mutant at the hormone response element showed that intramolecular interactions between the N and C termini of AR play a key functional role in vivo compared to intermolecular interactions between two neighboring ARs. These data provide a kinetic and mechanistic basis for regulation of gene expression by androgens and antiandrogens in living cells.

Insulin-like growth factor binding protein-3 (IGFBP-3), a secreted protein, has the intrinsic ability to induce apoptosis directly without binding insulin-like growth factors. Previous studies suggested that IGFBP-3 must be secreted to exert its biological functions. IGFBP-3 contains a nuclear localization signal (NLS), and exogenous IGFBP-3 is translocated into the nucleus, suggesting that both secretion and nuclear localization may play important roles in IGFBP-3 action. To address these questions, we fused yellow fluorescent protein (YFP) to mature IGFBP-3 lacking its signal peptide so that it would remain intracellular and mutated the C-terminal NLS of IGFBP-3, (228)KGRKR(232), to MDGEA. Following transfection of PC-3 human prostate cancer cells with these constructs, Western blots indicated that YFP-IGFBP-3 lacking a signal peptide was cell-associated and not present in the extracellular media. Moreover, the fusion protein was not N-glycosylated, indicating that it had not entered the secretory pathway. Confocal imaging showed that intracellular YFP-MDGEA-IGFBP-3 was predominantly cytoplasmic. Transient transfection of nonsecreted YFP-wild-type IGFBP-3 decreased cell viability, as assessed by staining with annexin V followed by flow cytometry. Induction of cell death was caspase-dependent, indicative of apoptosis. Apoptosis also was induced by the nonsecreted NLS mutant (YFP-MDGEA-IGFBP-3) alone and when the IGF-binding site also had been mutated. These results indicate that IGFBP-3 can induce apoptosis in an IGF-independent manner without being secreted or concentrated in the nucleus.

Eucaryotic gene transcriptional switches utilize changes both in the activity and composition of soluble transcription factor complexes, and epigenetic modifications to the chromatin template. Until recently, alternate states of promoter activity have been associated with the assembly of relatively stable multiprotein complexes on target genes, with transitions in the composition of these complexes occurring on the time scale of minutes or hours. The development of living cell techniques to characterize transcription factor function in real time has led to an alternate view of highly dynamic protein/template interactions. In addition, emerging evidence suggests that energy-dependent processes contribute significantly to the rapid movement of proteins in living cells, and to the exchange of sequence-specific DNA-binding proteins with regulatory elements. Potential mechanisms involved in the unexpectedly rapid flux of factor/template interactions are discussed in the context of a "return-to-template" model for transcription factor function.

We have identified a novel gene, six transmembrane protein of prostate 2 (STAMP2), named for its high sequence similarity to the recently identified STAMP1 gene. STAMP2 displays a tissue-restricted expression with highest expression levels in placenta, lung, heart, and prostate and is predicted to code for a 459-amino acid six transmembrane protein. Using a form of STAMP2 labeled with green flourescent protein (GFP) in quantitative time-lapse and immunofluorescence confocal microscopy, we show that STAMP2 is primarily localized to the Golgi complex, trans-Golgi network, and the plasma membrane. STAMP2 also localizes to vesicular-tubular structures in the cytosol and colocalizes with the Early Endosome Antigen1 (EEA1) suggesting that it may be involved in the secretory/endocytic pathways. STAMP2 expression is exquisitely androgen regulated in the androgen-sensitive, androgen receptor-positive prostate cancer cell line LNCaP, but not in androgen receptor-negative prostate cancer cell lines PC-3 and DU145. Analysis of STAMP2 expression in matched normal and tumor samples microdissected from prostate cancer specimens indicates that STAMP2 is overexpressed in prostate cancer cells compared with normal prostate epithelial cells. Furthermore, ectopic expression of STAMP2 in prostate cancer cells significantly increases cell growth and colony formation suggesting that STAMP2 may have a role in cell proliferation. Taken together, these data suggest that STAMP2 may contribute to the normal biology of the prostate cell, as well as prostate cancer progression.

Progesterone receptor (PR), a member of the nuclear receptor superfamily, is a key regulator of several processes in reproductive function. We have studied the dynamics of the interaction of PR with a natural target promoter in living cells through the use of fluorescence recovery after photobleaching (FRAP) analysis and also have characterized the dynamics of the interaction of PR with the mouse mammary tumor virus (MMTV) promoter reconstituted into chromatin in vitro. In photobleaching experiments, PR in the presence of the agonist R5020 exhibits rapid exchange with the MMTV promoter in living cells. Two PR antagonists, RU486 and ZK98299, have opposite effects on receptor dynamics in vivo. In the presence of RU486, PR binds to the promoter and is exchanged more slowly than the agonist-activated receptor. In contrast, PR bound to ZK98299 is not localized to the promoter and exhibits higher mobility in the nucleoplasm than the agonist-bound receptor. Significantly, PR bound to R5020 or RU486 can recruit the SWI/SNF chromatin remodeling complex to the promoter, but PR activated with ZK98299 cannot. Furthermore, we found ligand-specific active displacement of PR from the MMTV promoter during chromatin remodeling in vitro and conclude that the interaction of PR with chromatin is highly dynamic both in vivo and in vitro. We propose that factor displacement during chromatin remodeling is an important component of receptor mobility and that ligand-specific interactions with remodeling complexes can strongly influence receptor nuclear dynamics and rates of exchange with chromatin in living cells.

Genome structure and gene expression depend on a multitude of chromatin-binding proteins. The binding properties of these proteins to native chromatin in intact cells are largely unknown. Here, we describe an approach based on combined in vivo photobleaching microscopy and kinetic modeling to analyze globally the dynamics of binding of chromatin-associated proteins in living cells. We have quantitatively determined basic biophysical properties, such as off rate constants, residence time, and bound fraction, of a wide range of chromatin proteins of diverse functions in vivo. We demonstrate that most chromatin proteins have a high turnover on chromatin with a residence time on the order of seconds, that the major fraction of each protein is bound to chromatin at steady state, and that transient binding is a common property of chromatin-associated proteins. Our results indicate that chromatin-binding proteins find their binding sites by three-dimensional scanning of the genome space and our data are consistent with a model in which chromatin-associated proteins form dynamic interaction networks in vivo. We suggest that these properties are crucial for generating high plasticity in genome expression.

Through the use of novel imaging techniques, we have observed direct steroid receptor binding to a tandem array of a hormone-responsive promoter in living cells. We found that the glucocorticoid receptor (GR) exchanges rapidly with regulatory elements in the continued presence of ligand. We have also reconstituted a GR-dependent nucleoprotein transition with chromatin assembled on promoter DNA, and we discovered that GR is actively displaced from the chromatin template during the chromatin remodeling process. Using high-intensity UV laser crosslinking, we have observed highly periodic interactions of GR with promoter chromatin. These periodic binding events are dependent on GR-directed hSWI/SNF remodeling of the template and require the presence of ATP. Both the in vitro and in vivo results are consistent with a dynamic model ("hit-and-run") in which GR first binds to chromatin after ligand activation, recruits a remodeling activity, and is simultaneously lost from the template. We also find that receptor mobility in the nucleoplasm is strongly enhanced by molecular chaperones. These observations indicate that multiple mechanisms are involved in transient receptor interactions with nucleoplasmic targets.

Indirubin, a bis-indole obtained from various natural sources, is responsible for the reported antileukemia activity of a Chinese Medicinal recipe, Danggui Longhui Wan. However, its molecular mechanism of action is still not well understood. In addition to inhibition of cyclin-dependent kinases and glycogen synthase kinase-3, indirubins have been reported to activate the aryl hydrocarbon receptor (AhR), a cotranscriptional factor. Here, we confirm the interaction of AhR and indirubin using a series of indirubin derivatives and show that their binding modes to AhR and to protein kinases are unrelated. As reported for other AhR ligands, binding of indirubins to AhR leads to its nuclear translocation. Furthermore, the apparent survival of AhR-/- and +/+ cells, as measured by the MTT assay, is equally sensitive to the kinase-inhibiting indirubins. Thus, the cytotoxic effects of indirubins are AhR-independent and more likely to be linked to protein kinase inhibition. In contrast, a dramatic cytostatic effect, as measured by actual cell counts and associated with a sharp G1 phase arrest, is induced by 1-methyl-indirubins, a subfamily of AhR-active but kinase-inactive indirubins. As shown for TCDD (dioxin), this effect appears to be mediated through the AhR-dependent expression of p27(KIP1). Altogether these results suggest that AhR activation, rather than kinase inhibition, is responsible for the cytostatic effects of some indirubins. In contrast, kinase inhibition, rather than AhR activation, represents the main mechanism underlying the cytotoxic properties of this class of promising antitumor molecules.

Kallikreins (KLKs) are highly conserved serine proteases that play key roles in a variety of physiological and pathological processes. KLKs are secreted proteins that have extracellular substrates and function. For example, prostate-specific antigen (or KLK3) is a secreted protein that is widely used as a diagnostic marker for prostate cancer. KLK4 is a recently identified member of the kallikrein family that is regulated by androgens and is highly specific to prostate for expression. Here, we show that the gene product of KLK4, hK4, is the first member of the KLK family that is intracellularly localized. We provide strong evidence that the previously assigned first exon that was predicted to code for a signal peptide that would target hK4 for secretion is not part of the physiologically relevant form of KLK4 mRNA. In addition to detailed mapping of the KLK4 mRNA 5' end by RT-PCR, this conclusion is supported by predominantly nuclear localization of the hK4 protein in the cell, documented by both immunofluorescence and cell fractionation experiments. Furthermore, in addition to androgens, hK4 expression is regulated by estrogen and progesterone in prostate cancer cells. Finally, in situ hybridization on normal and hyperplastic prostate samples in tissue microarrays indicate that KLK4 is predominantly expressed in the basal cells of the normal prostate gland and overexpressed in prostate cancer. These data suggest that KLK4 has a unique structure and function compared with other members of the KLK family and may have a role in the biology and characterization of prostate cancer.

Live cell imaging has revealed the rapid mobility of steroid hormone receptors within nuclei and their dynamic exchange at transcriptionally active target sites. Although a number of other proteins have been shown to be highly mobile within nuclei, the identity of soluble factors responsible for orchestrating nuclear trafficking remains unknown. We have developed a previously undescribed in situ subnuclear trafficking assay that generates transcriptionally active nuclei, which are depleted of soluble factors required for the nuclear mobility of glucocorticoid (GR) and progesterone receptors (PR). Using this system and a fluorescence recovery after photobleaching technique, we demonstrate that nuclear mobility of GR recovered on incubation with reticulocyte lysate was inhibited by geldanamycin, a drug that blocks the chaperone activity of heat-shock protein 90. Direct proof of molecular chaperone involvement in steroid receptor subnuclear trafficking was provided by the ATP-dependent recovery of nuclear mobility of GR and PR on incubation with various combinations of purified chaperone and/or cochaperone proteins. Additionally, for both receptors, the inclusion of hormone during the recovery period leads to a retardation of nuclear mobility. Thus, our results provide a description of soluble nuclear mobility factors and furthermore demonstrate a previously unrecognized role for molecular chaperones in the regulation of steroid receptor function within the nucleus.

The p53 tumor suppressor protein plays a critical role in mediating cellular response to stress. Upon DNA damage, post-translational modifications stabilize and activate this nuclear phosphoprotein. To determine the effect of phosphorylation site mutants in the context of the whole p53 protein, we performed reporter assays in p53 and MDM2 knockout mouse embryonic fibroblasts transfected with full-length p53 constructs. We show that mutation of S37 causes a decrease in p53 transcriptional activity compared to wild-type p53. Our data further suggest that the dephosphorylation of p53 at S37 is a regulated event involving protein phosphatase 2A (PP2A). Coimmunoprecipitation and immunofluorescence microscopy studies demonstrate that PP2A and p53 associate with one another in vivo following gamma-irradiation. Consistent with these observations, phosphorylated S37 accumulates in cell extracts prepared from gamma-irradiated Molt-4 cells in the presence of okadaic acid. Furthermore, in vitro phosphatase assays show that PP2A dephosphorylates p53 at S37. These results suggest that dephosphorylation of p53 at S37 plays a role in the transcriptional regulation of the p53 protein in response to DNA damage.

BACKGROUND: Recent studies suggest that rotenone alters cell signal transduction pathways in a manner similar to glucocorticoids. Histological and biochemical markers of glucocorticoid effects in vivo, evaluated in our laboratories, provide further evidence for similarities in the activity of glucocorticoids and rotenone. The purpose of this study was to investigate the mechanism by which rotenone produces glucocorticoid-like effects. METHODS: Male B6C3F1 mice were treated for 7 days with rotenone (600 ppm in diet), the glucocorticoid antagonist RU486 (2 mg/kg/day, ip), corticosterone (2 mg/kg/day, ip), or both rotenone and RU 486. Control mice received drug-free diet and the vehicle (corn oil, ip). Following preservation in 10% neutral buffered formalin, tissues were embedded in paraffin. Sections were stained with hematoxylin, eosin, and were examined by light microscopy. Tissue sections were processed for in situ enzymatic end labeling of 3'-hydroxy-DNA strand breaks, a measure of apoptosis. Corticosterone was quantified in sera, using a solid phase radioimmunoassay kit. Cells (cell line 1470.2 derived from C127 mouse mammary adenocarcinoma cells) were transiently transfected with 5 &mgr;g of pLTRLuc and 1 &mgr;g of beta-Galactosidase expression vectors using a BTX square-wave pulser at 155 V, 4 pulses (40 ms each). Cells were then treated with dexamethasone, rotenone, or a mixture of both for 6 hr, harvested and assayed for luciferase and beta-Galactosidase activity. Using Root Mean Square (RMS) fit analysis (Alchemy trade mark, Tripose, Inc., St Louis, MO), we assessed possible structural similarities between rotenone and corticosterone, dehydrocorticosterone, glucocorticoid antagonists ZK 98.299, and RU 486. RMS fit was calculated by selecting three atoms in each of the molecules, followed by calculating the distance between these atoms. An RMS value of zero between two molecules indicates identical molecular characteristics. A positive value suggests diminished similarity with a value of 1 or higher excluding any such similarities. RESULTS: Although the stimulatory effect exerted by rotenone on hepatocellular apoptosis was in the opposite direction of that produced by the glucocorticoid antagonist RU 486, data suggested that rotenone does not directly activate the glucocorticoid receptor. Molecular fitting of rotenone to glucocorticoid receptor agonists and antagonists as well as examination of the transcriptional activation of a glucocorticoid-responsive reporter gene (Mouse MammaryTumorVirus) in response to rotenone indicated that it is highly unlikely that rotenone interacts directly with the glucocorticoid receptor. However, feeding male B6C3F1 mice a diet containing rotenone (600 ppm for 7 days) resulted in a 3-fold increase in serum levels of corticosterone relative to control animals. Corticosterone is the major glucocorticoid in rodents. CONCLUSION: Rotenone does not interact directly with the glucocorticoid receptor. Elevation of serum corticosterone levels in response to rotenone may explain the glucocorticoid-like effects of this compound, and may play a role in its anti-hepatocarcinogenic effect.

We have identified a novel gene, six transmembrane protein of prostate 1 (STAMP1), which is largely specific to prostate for expression and is predicted to code for a 490-amino acid six transmembrane protein. Using a form of STAMP1 labeled with green fluorescent protein in quantitative time-lapse and immunofluorescence confocal microscopy, we show that STAMP1 is localized to the Golgi complex, predominantly to the trans-Golgi network, and to the plasma membrane. STAMP1 also localizes to vesicular tubular structures in the cytosol and colocalizes with the early endosome antigen 1 (EEA1), suggesting that it may be involved in the secretory/endocytic pathways. STAMP1 is highly expressed in the androgen-sensitive, androgen receptor-positive prostate cancer cell line LNCaP, but not in androgen receptor-negative prostate cancer cell lines PC-3 and DU145. Furthermore, STAMP1 expression is significantly lower in the androgen-dependent human prostate xenograft CWR22 compared with the relapsed derivative CWR22R, suggesting that its expression may be deregulated during prostate cancer progression. Consistent with this notion, in situ analysis of human prostate cancer specimens indicated that STAMP1 is expressed exclusively in the epithelial cells of the prostate and its expression is significantly increased in prostate tumors compared with normal glands. Taken together, these data suggest that STAMP1 may have an important role in the normal prostate cell as well as in prostate cancer progression.

The aryl hydrocarbon receptor (AhR or dioxin receptor) is a ligand-activated transcription factor that heterodimerizes with the AhR nuclear translocator (ARNT/HIF-1beta) to form an AhR/ARNT transcription factor complex. This complex binds to specific DNA sites in the regulatory domains of numerous target genes and mediates the biological effects of exogenous ligands. Herein, we have investigated the subcellular distribution of the AhR/ARNT complex in response to ligand stimulation, by using live-cell confocal and high-resolution deconvolution microscopy. We found that unliganded AhR shows a predominantly cytoplasmic diffuse distribution in mouse hepatoma cells. On addition of ligand, AhR rapidly translocates to the nucleus and accumulates in multiple bright foci. Inhibition of transcription prevented the formation of AhR foci. Dual- and triple-immunolabeling experiments, combined with labeling of nascent RNA, showed that the foci are transcription sites, indicating that upon ligand stimulation, AhR is recruited to active transcription sites. The interaction of AhR with ARNT was both necessary and sufficient for the recruitment of AhR to transcription sites. These results indicate that AhR/ARNT complexes are recruited to specific subnuclear compartments in a ligand-dependent manner and that these foci represent the sites of AhR target genes.

The classic view of a transcriptional initiation complex is that of an assembly of factors with many protein-protein contacts, leading to a multi-component complex whose existence is a result of the stabilizing influence of the many intermolecular interactions. Recent findings from protein mobility experiments in living cells indicate that many kinds of nuclear factors move rapidly and exchange quickly with multiple targets. Two countervailing views of factor/regulatory site interactions emerge from the current literature.

Most of the steroid receptor family, with the exception of the estrogen receptor, are classically viewed as 'translocating receptors'. That is, they move from an exclusively, or principally, cytoplasmic distribution in the absence of hormone to a predominately nuclear localization in hormone stimulated cells. The estrogen receptor and the nuclear receptor family are found exclusively in the nucleus, both in hormone stimulated and hormone free cells. This behavior has now been studied with GFP-fusions in living cells, and has in general been confirmed. However, there are important exceptions, and new findings, particularly with regard to sub-nuclear localization. We propose that the intracellular distribution of both receptor classes is dependent not only on subcellular localization signals directly encoded in the receptors, but also on the nature and composition of the large, macromolecular complexes formed by each receptor. Furthermore, we find that most members of the receptor superfamily form focal accumulations within the nucleus in response to ligand, and suggest that these structures may participate in the biological life cycle of the receptors. Finally, we propose that receptor movement in the nucleus is highly dynamic, with the receptors undergoing constant exchange between genomic regulatory elements, multi-protein complexes with other transcription factor partners, and subnuclear structures that are as yet poorly defined.