Publications by authors named "Stewart Martin"

Article Synopsis
  • Poor survival rates in periampullary cancer indicate a need for better biomarkers and new treatments.
  • A study examined the protein expressions of thioredoxin (Trx), thioredoxin-interacting protein (TxNIP), and thioredoxin reductase (TrxR) in patients with pancreatic ductal adenocarcinoma (PDAC) and other related cancers using immunohistochemistry.
  • Results showed that high TrxR expression was linked to lymph node metastasis, while higher Trx expression was associated with improved overall survival, highlighting the prognostic value of these proteins in periampullary cancers.
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Protein tyrosine kinase 7 (PTK7), originally known as colon carcinoma kinase (CCK4), is an evolutionary conserved, catalytically defective transmembrane receptor involved in Wnt signalling. PTK7 has been identified as a potential therapeutic target, and a PTK7 antibody drug conjugate (PF-06647020; cofetuzumab pelidotin) has been investigated in phase I clinical trials for triple-negative breast cancer, ovarian cancer, and non-small cell lung cancer. PTK7 protein expression was evaluated in 1136 early-stage invasive breast tumours by immunohistochemistry.

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Background: Tumour hypoxia is a recognised cause of radiotherapy treatment resistance in head and neck squamous cell carcinoma (HNSCC). Current positron emission tomography-based hypoxia imaging techniques are not routinely available in many centres. We investigated if an alternative technique called oxygen-enhanced magnetic resonance imaging (OE-MRI) could be performed in HNSCC.

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Combinations of the topoisomerase II inhibitor doxorubicin and the poly (ADP-ribose) polymerase inhibitor olaparib offer potential drug-drug synergy for the treatment of triple negative breast cancers (TNBC). In this study we performed screening of combinations of these drugs, administered directly or encapsulated within polymer nanoparticles, in both 2D and in 3D spheroid models of breast cancer. A variety of assays were used to evaluate drug potency, and calculations of combination index (CI) values indicated that synergistic effects of drug combinations occurred in a molar-ratio dependent manner.

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DARPP-32 is a key regulator of protein-phosphatase-1 (PP-1) and protein kinase A (PKA), with its function dependent upon its phosphorylation state. We previously identified DKK1 and GRB7 as genes with linked expression using Artificial Neural Network (ANN) analysis; here, we determine protein expression in a large cohort of early-stage breast cancer patients. Low levels of DARPP-32 Threonine-34 phosphorylation and DKK1 expression were significantly associated with poor patient prognosis, while low levels of GRB7 expression were linked to better survival outcomes.

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Bone Morphogenetic Protein 7 (BMP7) is an extracellular signalling protein that belongs to the transforming growth factor-β (TGF- β) superfamily. Previous transcriptomic data suggested that BMP7 expression may be disrupted in ovarian carcinoma and may play an important role in the aggressiveness of the disease. However, the protein expression in patient tumours has not been well studied.

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Article Synopsis
  • The study aimed to investigate the relationship between p53 protein expression and survival rates in women with different types of ovarian cancer, particularly high-grade serous carcinoma (HGSC), endometrioid carcinoma (EC), and clear cell carcinoma (CCC), using a large cohort from the Ovarian Tumor Tissue Analysis (OTTA) consortium.
  • It was found that abnormal p53 expression patterns were prevalent in 93.4% of HGSC cases, but in EC and CCC, these abnormal patterns were linked to a significantly higher risk of death, indicating a poor prognosis.
  • The research concluded that while abnormal p53 expression doesn't affect survival in HGSC, it serves as a strong independent prognostic marker for EC and CCC,
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Introduction: The cytoskeletal protein ezrin is upregulated in many cancer types and is strongly associated with poor patient outcome. While the clinical and prognostic value of ezrin has been previously evaluated in breast cancer, most studies to date have been conducted in smaller cohorts (less than 500 cases) or have focused on specific disease characteristics. The current study is the largest of its kind to evaluate ezrin both at the protein and mRNA levels in early-stage breast cancer patients using the Nottingham (n = 1094) and METABRIC (n = 1980) cohorts, respectively.

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Objective: Oxygen-enhanced MRI (OE-MRI) or tissue oxygen-level dependent (TOLD) MRI is an imaging technique under investigation for its ability to quantify and map oxygen distributions within tumours. The aim of this study was to identify and characterise the research into OE-MRI for characterising hypoxia in solid tumours.

Methods: A scoping review of published literature was performed on the PubMed and Web of Science databases for articles published before 27 May 2022.

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The cytochrome P450 family of enzymes metabolise a wide range of compounds and play important roles in breast cancer pathogenesis due to their involvement in estrogen metabolism and the production of carcinogenic metabolites during this process. The orphan CYPs, CYP2S1, and CYP2W1 are reportedly upregulated in breast cancer. However, their expression and association with clinicopathological and survival parameters have not been previously assessed in a large cohort of breast cancers.

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KP167 is a novel hypoxia-activated prodrug (HAP), targeting cancer cells via DNA intercalating and alkylating properties. The single agent and radiosensitizing efficacy of KP167 and its parental comparator, AQ4N, were evaluated in 2D and 3D cultures of luminal and triple negative breast cancer (TNBC) cell lines and compared against DNA damage repair inhibitors. 2D normoxic treatment with the DNA repair inhibitors, Olaparib or KU-55933 caused, as expected, substantial radiosensitization (sensitiser enhancement ratio, SER of 1.

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The thioredoxin (Trx) system, a key antioxidant pathway, represents an attractive target for cancer therapy. This study investigated the chemotherapeutic and radiosensitising effects of a novel Trx reductase (TrxR) inhibitor, IQ10, on brain cancer cells and the underlying mechanisms of action. Five brain cancer cell lines and a normal cell type were used.

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The development of new blood and lymphatic vessels, through the process of angiogenesis and lymphangiogenesis, respectively, is critical to the development and growth of tumors, and integral to the process of metastasis. Lymphatic vessel density can be assessed as a surrogate measure of lymphangiogenesis in human tissue samples. Lymphatic vessel density has been shown to be associated with lymph node metastasis and patient survival in various solid tumor types.

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Virtual reality head mounted display (VR HMD) systems are increasingly utilised in combination with electroencephalography (EEG) in the experimental study of cognitive tasks. The aim of our investigation was to determine the similarities/differences between VR HMD and the computer screen (CS) in response to an n-back working memory task by comparing visual electrophysiological event-related potential (ERP) waveforms (N1/P1/P3 components). The same protocol was undertaken for VR HMD and CS with participants wearing the same EEG headcap.

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Article Synopsis
  • - PKA and PP1 are critical proteins in various signaling pathways and can be inhibited by DARPP-32; this study looked into their expression in over 1,100 breast cancer tumors to see how they relate to patient outcomes.
  • - Low levels of PKA protein were linked to poorer survival rates in breast cancer patients, especially among those with estrogen receptor-positive tumors, while PP1 expression did not show a similar association.
  • - Additionally, analysis of mRNA levels in a separate dataset revealed specific subunits of PKA and PP1 related to cancer survival, highlighting their potential roles in influencing breast cancer prognosis.
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Despite significant advances in treatment strategies over the past decade, selective treatment of breast cancer with limited side-effects still remains a great challenge. The cytochrome P450 (CYP) family of enzymes contribute to cancer cell proliferation, cell signaling and drug metabolism with implications for treatment outcomes. A clearer understanding of CYP expression is important in the pathogenesis of breast cancer as several isoforms play critical roles in metabolising steroid hormones and xenobiotics that contribute to the genesis of breast cancer.

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Radiotherapy is an effective treatment modality for breast cancer but, unfortunately, not all patients respond fully with a significant number experiencing local recurrences. Overexpression of thioredoxin and thioredoxin reductase has been reported to cause multidrug and radiation resistance - their inhibition may therefore improve therapeutic efficacy. Novel indolequinone compounds have been shown, in pancreatic cancer models, to inhibit thioredoxin reductase activity and exhibit potent anticancer activity.

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The recent outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated serious respiratory disease, coronavirus disease 2019 (COVID-19), poses a major threat to global public health. Owing to the lack of vaccine and effective treatments, many countries have been overwhelmed with an exponential spread of the virus and surge in the number of confirmed COVID-19 cases. Current standard diagnostic methods are inadequate for widespread testing as they suffer from prolonged turn-around times (>12 h) and mostly rely on high-biosafety-level laboratories and well-trained technicians.

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Article Synopsis
  • DARPP-32 is a key protein involved in neurotransmission and has a dual role: it inhibits protein phosphatase 1 (PP1) and can also inhibit protein kinase A (PKA) under certain conditions.
  • In a study involving 428 ovarian cancer patients, low levels of DARPP-32 expression were linked to worse overall and progression-free survival rates, indicating its potential as a prognostic marker.
  • Additionally, high levels of PP1 and Cdk5 expression were associated with shorter survival, further suggesting that these proteins could be valuable in predicting clinical outcomes for ovarian cancer patients.
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The thioredoxin (Trx) system is an important enzyme family that regulates cellular redox homeostasis. Protein expression of Trx system family members has been assessed in various cancers and linked to various clinicopathological variables, disease progression, treatment response and survival outcomes but information is lacking in brain tumours. Expression of the system was therefore examined, by immunohistochemistry in different brain tumour types, adult and paediatric cases, to determine if expression was of importance to clinical outcome.

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Cyclin-dependent kinase 5 (Cdk5) is an atypical member of the cyclin-dependent kinase family and functions as a serine/threonine kinase that can be activated by non-cyclin binding activators p35 or p39. Cdk5 expression and activity has been linked with the development and progression of cancer; however, its expression in breast cancer has not been fully described. Protein expression of Cdk5 was determined in a large cohort of early-stage invasive breast cancer tumours (n = 1110) with long-term follow-up data using immunohistochemistry.

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Article Synopsis
  • DARPP-32 (encoded by the PPP1R1B gene) is a protein that inhibits certain enzymes and is present in various cells, but its specific role in breast cancer is still being studied.
  • Research involving two cohorts of breast cancer patients showed that lower levels of DARPP-32 expression are linked to shorter survival times, indicating its potential as a prognostic marker.
  • The findings suggest that DARPP-32 expression, particularly in estrogen receptor-positive breast cancer, could help predict patient outcomes and may have clinical relevance in treatment decision-making.
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Change history: In Fig. 1b and c of this Letter, the inset times in the DIC and GFP microscopy images should be in minutes ('min') instead of seconds ('s'). This has not been corrected online.

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