• HUWE1 is a critical colonic tumour suppressor gene that prevents MYC signalling, DNA damage accumulation and tumour initiation.

      Myant, K; Cammareri, P; Hodder, M; Wills, J; Von Kriegsheim, A; Győrffy, B; Rashid, M; Polo, S; Maspero, E; Vaughan, Lynsey; et al. (2017-02)
      Cancer genome sequencing projects have identified hundreds of genetic alterations, often at low frequencies, raising questions as to their functional relevance. One exemplar gene is HUWE1, which has been found to be mutated in numerous studies. However, due to the large size of this gene and a lack of functional analysis of identified mutations, their significance to carcinogenesis is unclear. To determine the importance of HUWE1, we chose to examine its function in colorectal cancer, where it is mutated in up to 15 per cent of tumours. Modelling of identified mutations showed that they inactivate the E3 ubiquitin ligase activity of HUWE1. Genetic deletion of Huwe1 rapidly accelerated tumourigenic in mice carrying loss of the intestinal tumour suppressor gene Apc, with a dramatic increase in tumour initiation. Mechanistically, this phenotype was driven by increased MYC and rapid DNA damage accumulation leading to loss of the second copy of Apc The increased levels of DNA damage sensitised Huwe1-deficient tumours to DNA-damaging agents and to deletion of the anti-apoptotic protein MCL1. Taken together, these data identify HUWE1 as a bona fide tumour suppressor gene in the intestinal epithelium and suggest a potential vulnerability of HUWE1-mutated tumours to DNA-damaging agents and inhibitors of anti-apoptotic proteins.
    • Hybridization interactions between probesets in short oligo microarrays lead to spurious correlations.

      Okoniewski, Michal J; Miller, Crispin J; Paterson Institute For Cancer Research, Christie Hospital site, University of Manchester, Wilmslow Road, Manchester, M20 4BX, UK. MOkoniewski@PICR.man.ac.uk (2006)
      BACKGROUND: Microarrays measure the binding of nucleotide sequences to a set of sequence specific probes. This information is combined with annotation specifying the relationship between probes and targets and used to make inferences about transcript- and, ultimately, gene expression. In some situations, a probe is capable of hybridizing to more than one transcript, in others, multiple probes can target a single sequence. These 'multiply targeted' probes can result in non-independence between measured expression levels. RESULTS: An analysis of these relationships for Affymetrix arrays considered both the extent and influence of exact matches between probe and transcript sequences. For the popular HGU133A array, approximately half of the probesets were found to interact in this way. Both real and simulated expression datasets were used to examine how these effects influenced the expression signal. It was found not only to lead to increased signal strength for the affected probesets, but the major effect is to significantly increase their correlation, even in situations when only a single probe from a probeset was involved. By building a network of probe-probeset-transcript relationships, it is possible to identify families of interacting probesets. More than 10% of the families contain members annotated to different genes or even different Unigene clusters. Within a family, a mixture of genuine biological and artefactual correlations can occur. CONCLUSION: Multiple targeting is not only prevalent, but also significant. The ability of probesets to hybridize to more than one gene product can lead to false positives when analysing gene expression. Comprehensive annotation describing multiple targeting is required when interpreting array data.
    • Hydroxychloroquine/ chloroquine as a treatment choice or prophylaxis for Covid-19 at the primary care level in developing countries: A Primum non Nocere dilemma

      Medina MT; Moncada, Salvador; Faculty of Medical Sciences, National Autonomous University of Honduras, WFN Regional Director for Latin America, Tegucigalpa, Honduras. (2020)
      The Food and Drug Administration (FDA) warned against the use of Hydroxychloroquine or chloroquine for Covid-19 outside of a hospital or a clinical trial setting due to the risk of QT interval prolongation, ventricular tachycardia and the increased risk of these complications when combined with some antibiotics such as azithromycin. Several studies have reported no benefit of Hydroxychloroquine or chloroquine, when used alone or with a macrolide in COVID-19 hospitalized patients. Despite these warnings, in several developing countries the official guidelines for treatment of Covid-19 patients at the primary care level recommend Hydroxychloroquine and azithromycin, among other treatments, as the first-choice for mild symptomatic Covid-19 patients, asymptomatic contacts or for prophylaxis. In our opinion there is a primum non nocere dilemma during this Covid-19 pandemic. In order to solve this bioethical problem, we strongly recommend that a randomized controlled trial in a primary care setting be carried out as a matter of urgency in these areas of the world. Keywords: Bioethics; Clinical trials; Developing countries; Hydroxychloroquine/ chloroquine; Primary care.
    • A hypercoagulant tumour microenvironment promotes breast cancer progression, with effects inhibited by anticoagulants

      Blower, Emma; Castle, John; Santiago-Gomez, Angelica; Clarke, Robert B; Kirwan, Cliona C; Manchester Cancer and Thrombosis Team, The Oglesby Cancer Research Building, University of Manchester, Manchester, UK (2021)
      Background: Breast cancer patients have a four-fold increased risk of developing a venous thromboembolism (VTE). VTE is associated with increased mortality despite adjusting for cancer stage. Tissue Factor (TF) is expressed by breast cancer-associated ?broblasts as well as breast cancer epithelial cells. TF signals to promote cancer growth and metastasis. Rivaroxaban, a licensed oral anticoagulant that inhibits this TF-Factor VIIa (FVIIa)-Factor Xa (FXa) complex, could potentially be repurposed to target this procoagulant tumour microenvironment in breast cancer. Methods: Recombinant coagulation factors, lentivirally transduced TF over-expressing ?broblasts (TFF) and their control (CF) or conditioned media (TFFCM and CFCM), were cultured with oestrogen receptor positive (ER+) breast cancer cells (MCF-7) +/- Rivaroxaban or anti-TF antibody 10H10. Proliferation (sulforhodamine-B/EdU assay), migration (scratch/transwell assay) and stem cell activity (mammosphere forming e?ciency (MFE) assay) were assessed. The underlying mechanism was analysed with western blotting and quantitative PCR.Results: Recombinant TF,FVIIa and FXa versus control promoted proliferation and migration in MCF-7 cells (p<0.001), with these e?ects abrogated by Rivaroxaban (p<0.05). Recombinant TF,FVIIa and FXa increased phospho-ERK (p<0.01), CXCL8 (p<0.05) and VEGFA (p<0.0001) expression as compared to control, with CXCL8 and VEGFA inhibited by Rivaroxaban (p<0.01).TFFCM promoted proliferation, migration and stem cell activity in MCF-7 cells (p<0.05) as compared to CFCM, with these e?ects abrogated by 10H10 (proliferation, migration, MFE:p<0.05) and Rivaroxaban (migration, MFE:p<0.05). The cancer-promoting e?ects of TFFCM versus CFCM were associated with increased VEGFA (p<0.05) expression; which was reversed by 10H10 and Rivaroxaban (p<0.05). 3D co-culture of MCF-7s with TFF as compared to CF promoted cancer cell migration (p=0.04) and stem cell activity (MFE:p<0.0001), with these e?ects abrogated by 10H10 (migration:p=0.01, MFE:p=0.0028) and Rivaroxaban (migration:p= 0.0341, MFE:p=0.0003).Conclusion: A procoagulant microenvironment promotes proliferation, migration and stem cell activity in ER+ breast cancer in vitro which can be targeted by anticoagulants. Rivaroxaban could potentially be repurposed as anticancer therapy.
    • Hypersensitivity to very-low single radiation doses: its relationship to the adaptive response and induced radioresistance.

      Joiner, M C; Lambin, P; Malaise, E P; Robson, T; Arrand, J E; Skov, K A; Marples, Brian; Gray Laboratory, Mount Vernon Hospital, Northwood, Middlesex, UK. joiner@graylab.ac.uk (1996-11-04)
      There is now little doubt of the existence of radioprotective mechanisms, or stress responses, that are upregulated in response to exposure to small doses of ionizing radiation and other DNA-damaging agents. Phenomenologically, there are two ways in which these induced mechanisms operate. First, a small conditioning dose (generally below 30 cGy) may protect against a subsequent, separate, exposure to radiation that may be substantially larger than the initial dose. This has been termed the adaptive response. Second, the response to single doses may itself be dose-dependent so that small acute radiation exposures, or exposures at very low dose rates, are more effective per unit dose than larger exposures above the threshold where the induced radioprotection is triggered. This combination has been termed low-dose hypersensitivity (HRS) and induced radioresistance (IRR) as the dose increases. Both the adaptive response and HRS/IRR have been well documented in studies with yeast, bacteria, protozoa, algae, higher plant cells, insect cells, mammalian and human cells in vitro, and in studies on animal models in vivo. There is indirect evidence that the HRS/IRR phenomenon in response to single doses is a manifestation of the same underlying mechanism that determines the adaptive response in the two-dose case and that it can be triggered by high and low LET radiations as well as a variety of other stress-inducing agents such as hydrogen peroxide and chemotherapeutic agents although exact homology remains to be tested. Little is currently known about the precise nature of this underlying mechanism, but there is evidence that it operates by increasing the amount and rate of DNA repair, rather than by indirect mechanisms such as modulation of cell-cycle progression or apoptosis. Changed expression of some genes, only in response to low and not high doses, may occur within a few hours of irradiation and this would be rapid enough to explain the phenomenon of induced radioresistance although its specific molecular components have yet to be identified.
    • Hypofractionated breast radiotherapy for 1 week versus 3 weeks (FAST-Forward): 5-year efficacy and late normal tissue effects results from a multicentre, non-inferiority, randomised, phase 3 trial

      Murray Brunt, A; Haviland, JS; Wheatley, DA; Sydenham, MA; Alhasso, A; Bloomfield, DJ; Chan, C; Churn, M; Cleator, S; Coles, CE; et al. (2020)
      Background: We aimed to identify a five-fraction schedule of adjuvant radiotherapy (radiation therapy) delivered in 1 week that is non-inferior in terms of local cancer control and is as safe as an international standard 15-fraction regimen after primary surgery for early breast cancer. Here, we present 5-year results of the FAST-Forward trial. Methods: FAST-Forward is a multicentre, phase 3, randomised, non-inferiority trial done at 97 hospitals (47 radiotherapy centres and 50 referring hospitals) in the UK. Patients aged at least 18 years with invasive carcinoma of the breast (pT1-3, pN0-1, M0) after breast conservation surgery or mastectomy were eligible. We randomly allocated patients to either 40 Gy in 15 fractions (over 3 weeks), 27 Gy in five fractions (over 1 week), or 26 Gy in five fractions (over 1 week) to the whole breast or chest wall. Allocation was not masked because of the nature of the intervention. The primary endpoint was ipsilateral breast tumour relapse; assuming a 2% 5-year incidence for 40 Gy, non-inferiority was predefined as ?1·6% excess for five-fraction schedules (critical hazard ratio [HR] of 1·81). Normal tissue effects were assessed by clinicians, patients, and from photographs. This trial is registered at isrctn.com, ISRCTN19906132. Findings: Between Nov 24, 2011, and June 19, 2014, we recruited and obtained consent from 4096 patients from 97 UK centres, of whom 1361 were assigned to the 40 Gy schedule, 1367 to the 27 Gy schedule, and 1368 to the 26 Gy schedule. At a median follow-up of 71·5 months (IQR 71·3 to 71·7), the primary endpoint event occurred in 79 patients (31 in the 40 Gy group, 27 in the 27 Gy group, and 21 in the 26 Gy group); HRs versus 40 Gy in 15 fractions were 0·86 (95% CI 0·51 to 1·44) for 27 Gy in five fractions and 0·67 (0·38 to 1·16) for 26 Gy in five fractions. 5-year incidence of ipsilateral breast tumour relapse after 40 Gy was 2·1% (1·4 to 3·1); estimated absolute differences versus 40 Gy in 15 fractions were -0·3% (-1·0 to 0·9) for 27 Gy in five fractions (probability of incorrectly accepting an inferior five-fraction schedule: p=0·0022 vs 40 Gy in 15 fractions) and -0·7% (-1·3 to 0·3) for 26 Gy in five fractions (p=0·00019 vs 40 Gy in 15 fractions). At 5 years, any moderate or marked clinician-assessed normal tissue effects in the breast or chest wall was reported for 98 of 986 (9·9%) 40 Gy patients, 155 (15·4%) of 1005 27 Gy patients, and 121 of 1020 (11·9%) 26 Gy patients. Across all clinician assessments from 1-5 years, odds ratios versus 40 Gy in 15 fractions were 1·55 (95% CI 1·32 to 1·83, p<0·0001) for 27 Gy in five fractions and 1·12 (0·94 to 1·34, p=0·20) for 26 Gy in five fractions. Patient and photographic assessments showed higher normal tissue effect risk for 27 Gy versus 40 Gy but not for 26 Gy versus 40 Gy. Interpretation: 26 Gy in five fractions over 1 week is non-inferior to the standard of 40 Gy in 15 fractions over 3 weeks for local tumour control, and is as safe in terms of normal tissue effects up to 5 years for patients prescribed adjuvant local radiotherapy after primary surgery for early-stage breast cancer.
    • Hypoxia and angiogenic biomarkers in prostate cancer after external beam radiotherapy (EBRT) alone or combined with high-dose-rate brachytherapy boost (HDR-BTb)

      Bhattacharya, IS; Taghavi, Azar SM; Alonzi, R; Hoskin, Peter J; Institute of Cancer Research Clinical Trials and Statistics Unit (ICR-CTSU), London, United Kingdom (2019)
      PURPOSE: To investigate angiogenic and hypoxia biomarkers to predict outcome in patients receiving external beam radiotherapy (EBRT) alone or combined with high-dose-rate brachytherapy boost (HDR-BTb) for localised prostate cancer. METHODS: Prostate biopsy samples were collected prospectively in patients entered into a phase 3 randomised controlled trial of patients receiving EBRT or EBRT?+?HDR-BTb. Univariate and multivariate analyses using Cox proportional hazards model were performed to identify associations between immunohistochemical staining of hypoxia inducible factor 1 alpha (HIF1?), glucose transporter 1 (GLUT1), osteopontin (OPN) and microvessel density (MVD) using CD-34 antibody with clinical outcome. The primary endpoint was biochemical relapse free survival (BRFS) and secondary endpoint was distant metastasis free survival (DMFS). RESULTS: Immunohistochemistry was available for 204 patients. Increased OPN (Hazard ratio [HR] 2.38, 95% Confidence Interval [CI] 1.06-5.34, p?<?0.036) and GLUT1 (HR 2.36, 95%CI 1.39-4.01, p?<?0.001) expression were predictive of worse BRFS. Increased GLUT1 expression (HR 2.22, 1.02-4.84, p?=?0.045) was predictive of worse DMFS. Increased MVD (CD-34) (HR 1.82, 95%CI 1.06-3.14, p?=?0.03) and OPN (HR 1.82, 95%CI 1.06-3.14, p?=?0.03) but reduced GLUT1 expression (HR 0.40, 95%CI 0.20-0.79, p?=?0.009) were predictive of improved BRFS in patients receiving EBRT?+?HDR-BTb. CONCLUSION: Our data suggest angiogenic and hypoxia biomarkers may predict outcome and benefit of dose escalation, however further validation in prospective studies including hypoxia modification is needed. Trial registration number ISRCTN98241100, registered with ISRCTN at http://www.controlled-trials.com/isrctn/.
    • Hypoxia in head and neck cancer.

      Isa, Aidah Y; Ward, Timothy H; West, Catharine M L; Slevin, Nicholas J; Homer, Jarrod J; Department of Surgery, Christie Hospital, Manchester, UK. (2006-10)
      A high level of hypoxia in solid tumours is an adverse prognostic factor for the poor outcome of cancer patients following treatment. This review describes the status of research into finding a practical method for measuring hypoxia and treating hypoxic tumours. The application of such methodology would enable the selection of head and neck cancer treatment based on an individual's tumour oxygenation status. This individualization would include the selection not only of surgery or radiotherapy, but also of novel hypoxia-modification strategies.
    • Hypoxia response element-driven cytosine deaminase/5-fluorocytosine gene therapy system: a highly effective approach to overcome the dynamics of tumour hypoxia and enhance the radiosensitivity of prostate cancer cells in vitro.

      Marignol, Laure; Foley, Ruth; Southgate, Thomas D; Coffey, Mary; Hollywood, Donal; Lawler, Mark; Department of Haematology and Academic Unit of Clinical and Molecular Oncology, Institute of Molecular Medicine, St James's Hospital and Trinity College Dublin, Dublin, Ireland. marignol@tcd.ie (2009-02)
      BACKGROUND: We proposed to exploit hypoxia-inducible factor (HIF)-1alpha overexpression in prostate tumours and use this transcriptional machinery to control the expression of the suicide gene cytosine deaminase (CD) through binding of HIF-1alpha to arrangements of hypoxia response elements. CD is a prodrug activation enzyme, which converts inactive 5-fluorocytosine to active 5-fluorouracil (5-FU), allowing selective killing of vector containing cells. METHODS: We developed a pair of vectors, containing either five or eight copies of the hypoxia response element (HRE) isolated from the vascular endothelial growth factor (pH5VCD) or glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (pH8GCD) gene, respectively. The kinetics of the hypoxic induction of the vectors and sensitization effects were evaluated in 22Rv1 and DU145 cells in vitro. RESULTS: The CD protein as selectively detected in lysates of transiently transfected 22Rv1 and DU145 cells following hypoxic exposure. This is the first evidence of GAPDH HREs being used to control a suicide gene therapy strategy. Detectable CD levels were sustained upon reoxygenation and prolonged hypoxic exposures. Hypoxia-induced chemoresistance to 5-FU was overcome in both cell lines treated with this suicide gene therapy approach. Hypoxic transfectants were sensitized to prodrug concentrations that were ten-fold lower than those that are clinically relevant. Moreover, the surviving fraction of reoxygenated transfectants could be further reduced with the concomitant delivery of clinically relevant single radiation doses. CONCLUSIONS: This strategy thus has the potential to sensitize the hypoxic compartment of prostate tumours and improve the outcome of current therapies.
    • Hypoxia, Snail and incomplete epithelial-mesenchymal transition in breast cancer.

      Lundgren, K; Nordenskjöld, B; Landberg, Göran; Department of Laboratory Medicine, Center for Molecular Pathology, Malmö University Hospital, Lund University, Malmö SE-205 02, Sweden. (2009-11-17)
      BACKGROUND: Hypoxia is an element of the tumour microenvironment that impacts upon numerous cellular factors linked to clinical aggressiveness in cancer. One such factor, Snail, a master regulator of the epithelial-mesenchymal transition (EMT), has been implicated in key tumour biological processes such as invasion and metastasis. In this study we set out to investigate regulation of EMT in hypoxia, and the importance of Snail in cell migration and clinical outcome in breast cancer. METHODS: Four breast cancer cell lines were exposed to 0.1% oxygen and expression of EMT markers was monitored. The migratory ability was analysed following Snail overexpression and silencing. Snail expression was assessed in 500 tumour samples from premenopausal breast cancer patients, randomised to either 2 years of tamoxifen or no adjuvant treatment. RESULTS: Exposure to 0.1% oxygen resulted in elevated levels of Snail protein, along with changes in vimentin and E-cadherin expression, and in addition increased migration of MDA-MB-468 cells. Overexpression of Snail increased the motility of MCF-7, T-47D and MDA-MB-231 cells, whereas silencing of the protein resulted in decreased migratory propensity of MCF-7, MDA-MB-468 and MDA-MB-231 cells. Moreover, nuclear Snail expression was associated with tumours of higher grade and proliferation rate, but not with disease recurrence. Interestingly, Snail negativity was associated with impaired tamoxifen response (P=0.048). CONCLUSIONS: Our results demonstrate that hypoxia induces Snail expression but generally not a migratory phenotype, suggesting that hypoxic cells are only partially pushed towards EMT. Furthermore, our study supports the link between Snail and clinically relevant features and treatment response.
    • Hypoxia-induced cytotoxic drug resistance in osteosarcoma is independent of HIF-1alpha.

      Adamski, J K; Price, Andrew; Dive, Caroline; Makin, Guy W J; Clinical and Experimental Pharmacology, Paterson Institute for Cancer Research, Manchester, United Kingdom ; Institute of Cancer Sciences, Manchester Cancer Research Centre, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom ; Department of Paediatric Oncology, Royal Manchester Children's Hospital, Manchester, United Kingdom. (2013)
      Survival rates from childhood cancer have improved dramatically in the last 40 years, such that over 80% of children are now cured. However in certain subgroups, including metastatic osteosarcoma, survival has remained stubbornly poor, despite dose intensive multi-agent chemotherapy regimens, and new therapeutic approaches are needed. Hypoxia is common in adult solid tumours and is associated with treatment resistance and poorer outcome. Hypoxia induces chemotherapy resistance in paediatric tumours including neuroblastoma, rhabdomyosarcoma and Ewing's sarcoma, in vitro, and this drug resistance is dependent on the oxygen-regulated transcription factor hypoxia inducible factor-1 (HIF-1). In this study the effects of hypoxia on the response of the osteosarcoma cell lines 791T, HOS and U2OS to the clinically relevant cytotoxics cisplatin, doxorubicin and etoposide were evaluated. Significant hypoxia-induced resistance to all three agents was seen in all three cell lines and hypoxia significantly reduced drug-induced apoptosis. Hypoxia also attenuated drug-induced activation of p53 in the p53 wild-type U2OS osteosarcoma cells. Drug resistance was not induced by HIF-1α stabilisation in normoxia by cobalt chloride nor reversed by the suppression of HIF-1α in hypoxia by shRNAi, siRNA, dominant negative HIF or inhibition with the small molecule NSC-134754, strongly suggesting that hypoxia-induced drug resistance in osteosarcoma cells is independent of HIF-1α. Inhibition of the phosphoinositide 3-kinase (PI3K) pathway using the inhibitor PI-103 did not reverse hypoxia-induced drug resistance, suggesting the hypoxic activation of Akt in osteosarcoma cells does not play a significant role in hypoxia-induced drug resistance. Targeting hypoxia is an exciting prospect to improve current anti-cancer therapy and combat drug resistance. Significant hypoxia-induced drug resistance in osteosarcoma cells highlights the potential importance of hypoxia as a target to reverse drug resistance in paediatric osteosarcoma. The novel finding of HIF-1α independent drug resistance suggests however other hypoxia related targets may be more relevant in paediatric osteosarcoma.
    • Hypoxia-induced secretion stimulates breast cancer stem cell regulatory signalling pathways

      Jacobsson, H; Harrison, Hannah; Hughes, E; Persson, E; Rhost, S; Fitzpatrick, P; Gustafsson, A; Andersson, D; Gregersson, P; Magnusson, Y; et al. (2019)
      It is well known that tumor cells are dependent on communication with the tumor microenvironment. Previously, it has been shown that hypoxia induces pronounced, diverse and direct effects on cancer stem cell (CSC) qualities in different breast cancer subtypes. Here, we describe the mechanism by which hypoxia-induced secretion influence CSC spreading. Conditioned media from estrogen receptor (ER)-? positive hypoxic breast cancer cell cultures increased the fraction of CSCs compared to normal growth conditions, as determined using sets of CSC assays and model systems. In contrast, media from ER?-negative hypoxic cell cultures instead decreased this key subpopulation of cancer cells. Further, there was a striking overrepresentation of JAK-STAT-associated cytokines in both the ER?-positive and ER?-negative linked hypoxic responses as determined by a protein screen of the conditioned media. JAK-STAT inhibitors and knockdown experiments further supported the hypothesis that this pathway is critical for the CSC activating and inactivating effects induced by hypoxic secretion. We also observed that the interleukin (IL)-6 -JAK2-STAT3 axis was specifically central for the ER?-negative hypoxic behaviour. Our results underline the importance of considering breast cancer subtypes in treatments targeting JAK-STAT or hypoxia-associated processes, and indicate that hypoxia is not only a confined tumor biological event, but also influences key tumor properties in widespread normoxic microenvironments. This article is protected by copyright. All rights reserved.
    • Hypoxia-mediated down-regulation of Bid and Bax in tumors occurs via hypoxia-inducible factor 1-dependent and -independent mechanisms and contributes to drug resistance.

      Erler, Janine T; Cawthorne, Christopher; Williams, Kaye J; Koritzinsky, Marianne; Wouters, Bradley G; Wilson, Claire L; Miller, Crispin J; Demonacos, Costas; Stratford, Ian J; Dive, Caroline; et al. (2004-04)
      Solid tumors with disorganized, insufficient blood supply contain hypoxic cells that are resistant to radiotherapy and chemotherapy. Drug resistance, an obstacle to curative treatment of solid tumors, can occur via suppression of apoptosis, a process controlled by pro- and antiapoptotic members of the Bcl-2 protein family. Oxygen deprivation of human colon cancer cells in vitro provoked decreased mRNA and protein levels of proapoptotic Bid and Bad. Hypoxia-inducible factor 1 (HIF-1) was dispensable for the down-regulation of Bad but required for that of Bid, consistent with the binding of HIF-1alpha to a hypoxia-responsive element (positions -8484 to -8475) in the bid promoter. Oxygen deprivation resulted in proteosome-independent decreased expression of Bax in vitro, consistent with a reduction in global translation efficiency. The physiological relevance of Bid and Bax down-regulation was confirmed in tumors in vivo. Oxygen deprivation resulted in decreased drug-induced apoptosis and clonogenic resistance to agents with different mechanisms of action. The contribution of Bid and/or Bax down-regulation to drug responsiveness was demonstrated by the relative resistance of normoxic cells that had no or reduced expression of Bid and/or Bax and by the finding that forced expression of Bid in hypoxic cells resulted in increased sensitivity to the topoisomerase II inhibitor etoposide.
    • Hypoxia-targeted over-expression of carboxylesterase as a means of increasing tumour sensitivity to irinotecan (CPT-11).

      Matzow, Torkjel; Cowen, Rachel L; Williams, Kaye J; Telfer, Brian A; Flint, Pamela J; Southgate, Thomas D; Saunders, Mark P; Paterson Institute for Cancer Research, Christie Hospital NHS Trust, and School of Pharmacy and Pharmaceutical Sciences, University of Manchester, UK. (2007-04)
      The induced expression of carboxylesterase (CE) enzymes, which convert the prodrug irinotecan (CPT-11) into its active cytotoxic metabolite SN-38, constitutes a promising strategy for cancer gene therapy. By incorporating hypoxia-responsive elements (HREs) in conjunction with the transgene, expression can be targeted specifically to hypoxic tissues (such as solid tumours), expressing the hypoxia-inducible factor 1 (HIF-1). We have constructed a recombinant adenoviral vector, AdHRE-rCE, encoding the cDNA for the highly efficient rabbit liver CE (rCE), under the control of a HRE derived from the human phosphoglycerate kinase 1 (PGK-1) gene in conjunction with a minimal SV40 promoter. In vitro, HT1080 fibrosarcoma and SW480 colon carcinoma cells demonstrated an approximately 10-fold hypoxia-dependent induction in CE expression following pre-infection with AdHRE-rCE, which led to a15-30-fold increased sensitivity to CPT-11. Furthermore, in vivo, SW480 tumour xenografts infected with AdHRE-rCE demonstrated a 2-fold decrease in tumour doubling time, when combined with 7 days of CPT-11 treatment, in comparison to mock-infected controls, with rCE expression shown to be limited to hypoxic regions only. As the cytotoxicity of CPT-11 is reduced under hypoxic conditions, over-expression of a highly efficient CE such as rCE under hypoxia control within these hypoxic cells could reverse this effect and, therefore, form the basis for future clinical treatment strategies.
    • Hypoxic activation of glucose-6-phosphate dehydrogenase controls the expression of genes involved in the pathogenesis of pulmonary hypertension through the regulation of DNA methylation

      Joshi SR; Kitagawa A, Jacob C; Hashimoto R; Dhagia V; Ramesh A; Zheng C; Zhang H; Jordan, Allan M; Waddell, Ian D; Leopold J; et al. (2020)
    • Hypoxic human cancer cells are sensitized to BH-3 mimetic–induced apoptosis via downregulation of the Bcl-2 protein Mcl-1.

      Harrison, Luke R; Micha, Dimitra; Brandenburg, Martin; Simpson, Kathryn L; Morrow, Christopher J; Denneny, Olive; Hodgkinson, Cassandra L; Yunus, Zaira; Dempsey, Clare E; Roberts, Darren L; et al. (2011-03-01)
      Solid tumors contain hypoxic regions in which cancer cells are often resistant to chemotherapy-induced apoptotic cell death. Therapeutic strategies that specifically target hypoxic cells and promote apoptosis are particularly appealing, as few normal tissues experience hypoxia. We have found that the compound ABT-737, a Bcl-2 homology domain 3 (BH-3) mimetic, promotes apoptotic cell death in human colorectal carcinoma and small cell lung cancer cell lines exposed to hypoxia. This hypoxic induction of apoptosis was mediated through downregulation of myeloid cell leukemia sequence 1 (Mcl-1), a Bcl-2 family protein that serves as a biomarker for ABT-737 resistance. Downregulation of Mcl-1 in hypoxia was independent of hypoxia-inducible factor 1 (HIF-1) activity and was consistent with decreased global protein translation. In addition, ABT-737 induced apoptosis deep within tumor spheroids, consistent with an optimal hypoxic oxygen tension being necessary to promote ABT-737–induced cell death. Tumor xenografts in ABT-737–treated mice also displayed significantly more apoptotic cells within hypoxic regions relative to normoxic regions. Synergies between ABT-737 and other cytotoxic drugs were maintained in hypoxia, suggesting that this drug may be useful in combination with chemotherapeutic agents. Taken together, these findings suggest that Mcl-1–sparing BH-3 mimetics may induce apoptosis in hypoxic tumor cells that are resistant to other chemotherapeutic agents and may have a role in combinatorial chemotherapeutic regimens for treatment of solid tumors.
    • IAPs as a target for anticancer therapy.

      Danson, Sarah; Dean, Emma J; Dive, Caroline; Ranson, Malcolm R; Christie Hospital NHS Trust and Paterson Institute for Cancer Research, Wilmslow Road, Manchester, M20 4BX, United Kingdom. s.danson@sheffield.ac.uk (2007-12)
      The avoidance of apoptosis is one of the hallmarks of cancer cells. In addition, failure to induce apoptosis by anticancer agents, either due to limitations of the drug or the tumour cell evading apoptosis, is a reason for chemotherapeutic failure. Two general pathways for apoptotic cell death have been characterised, the extrinsic and intrinsic pathways which merge in the final common pathway. X-linked inhibitor of apoptosis protein (XIAP) is an anti-apoptotic protein in the final common pathway that inhibits caspases and suppresses apoptosis. XIAP is over-expressed in many cancer cell lines and cancer tissues. High XIAP expression has been correlated with resistance to chemotherapy and radiotherapy and to poor clinical outcome by some investigators. Manipulation of apoptosis is an attractive therapeutic concept. Much effort has been spent on inhibiting the anti-apoptotic protein, B cell lymphoma gene 2 (Bcl-2) which is part of the intrinsic pathway. Now attention is turning to inhibition of XIAP as a cancer drug target. It has been argued that it is more effective to block the final common pathway rather than just the intrinsic arm. Inhibition of XIAP can be with either antisense oligonucleotides (ASO) or small molecule inhibitors. In vitro, XIAP antagonists produce XIAP knockdown and apoptosis which is associated with sensitisation of tumour cells to radiotherapy and cytotoxic drugs. In vivo, XIAP antagonists have antitumour effects and sensitise tumours to the effects of chemotherapy. This review will summarise the preclinical data for both ASO and small molecule inhibition of XIAP and discuss emerging Phase I data. Future strategies for manipulation of XIAP and the clinical development of XIAP inhibitors will be discussed.
    • Id helix-loop-helix proteins antagonize pax transcription factor activity by inhibiting DNA binding.

      Roberts, E Claire; Deed, Richard W; Inoue, Toshiaki; Norton, John D; Sharrocks, Andrew D; Department of Biochemistry and Genetics, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom. (2001-01)
      The Id subfamily of helix-loop-helix (HLH) proteins plays a fundamental role in the regulation of cellular proliferation and differentiation. The major mechanism by which Id proteins are thought to inhibit differentiation is through interaction with other HLH proteins and inhibition of their DNA-binding activity. However, Id proteins have also been shown to interact with other proteins involved in regulating cellular proliferation and differentiation, suggesting a more widespread regulatory function. In this study we demonstrate functional interactions between Id proteins and members of the Pax-2/-5/-8 subfamily of paired-domain transcription factors. Members of the Pax transcription factor family have key functions in regulating several developmental processes exemplified by B lymphopoiesis, in which Pax-5 plays an essential role. Id proteins bind to Pax proteins in vitro and in vivo. Binding occurs through the paired DNA-binding domain of the Pax proteins and results in the disruption of DNA-bound complexes containing Pax-2, Pax-5, and Pax-8. In vivo, Id proteins modulate the transcriptional activity mediated by Pax-5 complexes on the B-cell-specific mb-1 promoter. Our results therefore demonstrate a novel facet of Id function in regulating cellular differentiation by functionally antagonizing the action of members of the Pax transcription factor family.
    • Id helix-loop-helix proteins in cell growth and differentiation.

      Norton, John D; Deed, Richard W; Craggs, Graham; Sablitzky, F; Cancer Research Campaign Dept of Gene Regulation, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, UK. JNorton@picr.man.ac.uk (1998-02)
      Id helix-loop-helix proteins function at a general level as positive regulators of cell growth and as negative regulators of cell differentiation. They act as dominant-negative antagonists of other helix-loop-helix transcription factors, which drive cell lineage commitment and differentiation in diverse cell types of higher eukaryotes. In addition, the functions of Id proteins are integrated with cell-cycle-regulatory pathways orchestrated by cyclin-dependent kinases and the retinoblastoma protein. Here, some of the recent advances that highlight the importance of Id proteins as regulatory intermediates for coordinating differentiation-linked gene expression with cell-cycle control in response to extracellular signalling are reviewed.
    • Id helix-loop-helix proteins inhibit nucleoprotein complex formation by the TCF ETS-domain transcription factors.

      Yates, Paula R; Atherton, Graham T; Deed, Richard W; Norton, John D; Sharrocks, Andrew D; Department of Biochemistry and Genetics, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH. (1999-02-15)
      The Id subfamily of helix-loop-helix (HLH) proteins plays a fundamental role in the regulation of cellular proliferation and differentiation. Id proteins are thought to inhibit differentiation mainly through interaction with other HLH proteins and by blocking their DNA-binding activity. Members of the ternary complex factor (TCF) subfamily of ETS-domain proteins have key functions in regulating immediate-early gene expression in response to mitogenic stimulation. TCFs form DNA-bound complexes with the serum response factor (SRF) and are direct targets of MAP kinase (MAPK) signal transduction cascades. In this study we demonstrate functional interactions between Id proteins and TCFs. Ids bind to the ETS DNA-binding domain and disrupt the formation of DNA-bound complexes between TCFs and SRF on the c-fos serum response element (SRE). Inhibition occurs by disrupting protein-DNA interactions with the TCF component of this complex. In vivo, the Id proteins cause down-regulation of the transcriptional activity mediated by the TCFs and thereby block MAPK signalling to SREs. Therefore, our results demonstrate a novel facet of Id function in the coordination of mitogenic signalling and cell cycle entry.