E3 ubiquitin ligase UBR5 modulates circadian rhythm by facilitating the ubiquitination and degradation of the key clock transcription factor BMAL1.

The circadian clock is the inner rhythm of life activities and is controlled by a self-sustained and endogenous molecular clock, which maintains a ~ 24 h internal oscillation. As the core element of the circadian clock, BMAL1 is susceptible to degradation through the ubiquitin-proteasome system (UPS). Nevertheless, scant information is available regarding the UPS enzymes that intricately modulate both the stability and transcriptional activity of BMAL1, affecting the cellular circadian rhythm. In this work, we identify and validate UBR5 as a new E3 ubiquitin ligase that interacts with BMAL1 by using affinity purification, mass spectrometry, and biochemical experiments. UBR5 overexpression induced BMAL1 ubiquitination, leading to diminished stability and reduced protein level of BMAL1, thereby attenuating its transcriptional activity. Consistent with this, UBR5 knockdown increases the BMAL1 protein. Domain mapping discloses that the C-terminus of BMAL1 interacts with the N-terminal domains of UBR5. Similarly, cell-line-based experiments discover that HYD, the UBR5 homolog in Drosophila, could interact with and downregulate CYCLE, the BMAL1 homolog in Drosophila. PER2-luciferase bioluminescence real-time reporting assay in a mammalian cell line and behavioral experiments in Drosophila reveal that UBR5 or hyd knockdown significantly reduces the period of the circadian clock. Therefore, our work discovers a new ubiquitin ligase UBR5 that regulates BMAL1 stability and circadian rhythm and elucidates the underlying molecular mechanism. This work provides an additional layer of complexity to the regulatory network of the circadian clock at the post-translational modification level, offering potential insights into the modulation of the dysregulated circadian rhythm.

Fam60a defines a variant Sin3a-Hdac complex in embryonic stem cells required for self-renewal.

Sin3a is the central scaffold protein of the prototypical Hdac1/2 chromatin repressor complex, crucially required during early embryonic development for the growth of pluripotent cells of the inner cell mass. Here, we compare the composition of the Sin3a-Hdac complex between pluripotent embryonic stem (ES) and differentiated cells by establishing a method that couples two independent endogenous immunoprecipitations with quantitative mass spectrometry. We define the precise composition of the Sin3a complex in multiple cell types and identify the Fam60a subunit as a key defining feature of a variant Sin3a complex present in ES cells, which also contains Ogt and Tet1. Fam60a binds on H3K4me3-positive promoters in ES cells, together with Ogt, Tet1 and Sin3a, and is essential to maintain the complex on chromatin. Finally, we show that depletion of Fam60a phenocopies the loss of Sin3a, leading to reduced proliferation, an extended G1-phase and the deregulation of lineage genes. Taken together, Fam60a is an essential core subunit of a variant Sin3a complex in ES cells that is required to promote rapid proliferation and prevent unscheduled differentiation.

An Insight Into the Driver Mutations and Molecular Mechanisms Underlying Mucinous Adenocarcinoma of the Rectum.

BACKGROUND: Mucinous adenocarcinoma of the rectum accounts for 10% of all rectal cancers and has an impaired response to neoadjuvant chemoradiotherapy and worse overall survival. To date, insufficient genomic research has been performed on this histological subtype. OBJECTIVE: This study aims to define the mismatch repair deficiency rate and the driver mutations underpinning mucinous adenocarcinoma of the rectum and to compare it with rectal adenocarcinoma not otherwise specified. DESIGN: Immunohistochemistry and sequencing were performed on tumor samples from our tumor biobank. SETTINGS: This study was conducted across 2 tertiary referral centers. PATIENTS: Patients with mucinous adenocarcinoma and rectal adenocarcinoma not otherwise specified who underwent rectal resection between 2008 and 2018 were included. MAIN OUTCOME MEASURES: Mismatch repair status was performed by immunohistochemical staining. Mutations in the panel of oncogenes and tumor suppressor genes were determined by sequencing on the MiSeq V3 platform. RESULTS: The study included 33 patients with mucinous adenocarcinoma of the rectum and 100 patients with rectal adenocarcinoma not otherwise specified. Those with mucinous adenocarcinoma had a mismatch repair deficiency rate of 12.1% compared to 2.0% in the adenocarcinoma not otherwise specified cohort (p = 0.04). Mucinous adenocarcinoma and adenocarcinoma not otherwise specified rectal tumors had similar mutation frequencies in most oncogenes and tumor suppressor genes. No difference was found in the KRAS mutation rate (50.0% vs 37.1%, p = 0.29) or BRAF mutation rate (6.7% vs 3.1%, p = 0.34) between the cohorts. No difference was found between the cohorts regarding recurrence-free (p = 0.29) or overall survival (p = 0.14). LIMITATIONS: The major limitations of this study were the use of formalin-fixed, paraffin-embedded tissue over fresh-frozen tissue and the small number of patients included, in particular, in the mucinous rectal cohort. CONCLUSIONS: Most mucinous rectal tumors develop and progress along the chromosomal instability pathway. Further research in the form of transcriptomics, proteomics, and analysis of the effects of the mucin barrier may yield valuable insights into the mechanisms of resistance to chemoradiotherapy in this cohort. See Video Abstract at http://links.lww.com/DCR/B464. UNA PERCEPCIN SOBRE MUTACIONES IMPULSORAS Y MECANISMOS MOLECULARES SUBYACENTES AL ADENOCARCINOMA MUCINOSO DEL RECTO: ANTECEDENTES:El adenocarcinoma mucinoso del recto, representa el 10% de todos los cánceres rectales y tiene una respuesta deficiente a la quimioradioterapia neoadyuvante y una peor supervivencia en general. A la fecha, se han realizado muy pocas investigaciones genómicas sobre este subtipo histológico.OBJETIVO:Definir la tasa de deficiencia en la reparación de desajustes y mutaciones impulsoras, que sustentan el adenocarcinoma mucinoso del recto y compararlo con el adenocarcinoma rectal no especificado de otra manera.DISEÑO:Se realizaron inmunohistoquímica y secuenciación en muestras tumorales de nuestro biobanco de tumores.AJUSTE:El estudio se realizó en dos centros de referencia terciarios.PACIENTES:Se incluyeron pacientes con adenocarcinoma mucinoso y adenocarcinoma no especificado de otra manera, sometidos a resección rectal entre 2008 y 2018.PRINCIPALES MEDIDAS DE RESULTADO:El estado de reparación de desajustes se realizó mediante tinción inmunohistoquímica. Las mutaciones en el panel de oncogenes y genes supresores de tumores, se determinaron mediante secuenciación en la plataforma MiSeq V3.RESULTADOS:El estudio incluyó a 33 pacientes con adenocarcinoma mucinoso del recto y 100 pacientes con adenocarcinoma del recto no especificado de otra manera. Aquellos con adenocarcinoma mucinoso, tenían una tasa de deficiencia de reparación de desajustes del 12,1% en comparación con el 2,0% en la cohorte de adenocarcinoma no especificado de otra manera (p = 0,04). El adenocarcinoma mucinoso y el adenocarcinoma no especificado de otra manera, tuvieron frecuencias de mutación similares en la mayoría de los oncogenes y genes supresores de tumores. No se encontraron diferencias en la tasa de mutación de KRAS (50,0% frente a 37,1%, p = 0,29) o la tasa de mutación de BRAF (6,7% frente a 3,1%, p = 0,34) entre las cohortes. No se encontraron diferencias entre las cohortes con respecto a la supervivencia libre de recurrencia (p = 0,29) o la supervivencia global (p = 0,14).LIMITACIONES:Las mayores limitaciones de este estudio, fueron el uso de tejido embebido en parafina y fijado con formalina, sobre el tejido fresco congelado y el pequeño número de pacientes incluidos, particularmente en la cohorte mucinoso rectal.CONCLUSIONES:La mayoría de los tumores rectales mucinosos se desarrollan y progresan a lo largo de la vía de inestabilidad cromosómica. La investigación adicional en forma transcriptómica, proteómica y análisis de los efectos de la barrera de la mucina, puede proporcionar información valiosa sobre los mecanismos de resistencia a la quimioradioterapia, en esta cohorte. Consulte Video Resumen en http://links.lww.com/DCR/B464.

FKBPL-based peptide, ALM201, targets angiogenesis and cancer stem cells in ovarian cancer.

BACKGROUND: ALM201 is a therapeutic peptide derived from FKBPL that has previously undergone preclinical and clinical development for oncology indications and has completed a Phase 1a clinical trial in ovarian cancer patients and other advanced solid tumours. METHODS: In vitro, cancer stem cell (CSC) assays in a range of HGSOC cell lines and patient samples, and in vivo tumour initiation, growth delay and limiting dilution assays, were utilised. Mechanisms were determined by using immunohistochemistry, ELISA, qRT-PCR, RNAseq and western blotting. Endogenous FKBPL protein levels were evaluated using tissue microarrays (TMA). RESULTS: ALM201 reduced CSCs in cell lines and primary samples by inducing differentiation. ALM201 treatment of highly vascularised Kuramochi xenografts resulted in tumour growth delay by disruption of angiogenesis and a ten-fold decrease in the CSC population. In contrast, ALM201 failed to elicit a strong antitumour response in non-vascularised OVCAR3 xenografts, due to high levels of IL-6 and vasculogenic mimicry. High endogenous tumour expression of FKBPL was associated with an increased progression-free interval, supporting the protective role of FKBPL in HGSOC. CONCLUSION: FKBPL-based therapy can (i) dually target angiogenesis and CSCs, (ii) target the CD44/STAT3 pathway in tumours and (iii) is effective in highly vascularised HGSOC tumours with low levels of IL-6.

Dysregulated mitogen-activated protein kinase signalling as an oncogenic basis for clear cell sarcoma of the kidney.

The oncogenic mechanisms and tumour biology underpinning clear cell sarcoma of the kidney (CCSK), the second commonest paediatric renal malignancy, are poorly understood and currently, therapy depends heavily on doxorubicin with cardiotoxic side-effects. Previously, we characterized the balanced t(10;17)(q22;p13) chromosomal translocation, identified at that time as the only recurrent genetic aberration in CCSK. This translocation results in an in-frame fusion of the genes YWHAE (encoding 14-3-3ϵ) and NUTM2, with a somatic incidence of 12%. Clinico-pathological features of that cohort suggested that this aberration might be associated with higher stage and grade disease. Since no primary CCSK cell line exists, we generated various stably transfected cell lines containing doxycycline-inducible HA-tagged YWHAE-NUTM2, in order to study the effect of expressing this transcript. 14-3-3ϵ-NUTM2-expressing cells exhibited significantly greater cell migration compared to isogenic controls. Gene and protein expression studies were indicative of dysregulated MAPK/PI3K-AKT signalling, and by blocking these pathways using neutralizing antibodies, the migratory advantage conferred by the transcript was abrogated. Importantly, CCSK tumour samples similarly show up-regulation/activation of these pathways. These results support the oncogenic role of 14-3-3ϵ-NUTM2 in CCSK and provide avenues for the exploration of novel therapeutic approaches. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The Emerging Role of Non-traditional Ubiquitination in Oncogenic Pathways.

The addition of ubiquitin to a target protein has long been implicated in the process of degradation and is the primary mediator of protein turnover in the cell. Recently, however, many non-proteolytic functions of ubiquitination have emerged as key regulators of cellular homeostasis. In this review, we will describe the various non-traditional functions of ubiquitination, with particular focus on how they can be used as signaling entities in cancer formation and progression. Elaboration of this topic can lead to a better understanding of oncogenic mechanisms, as well as the discovery of novel druggable proteins within the ubiquitin pathway.

De novo post-diagnosis statin use, breast cancer-specific and overall mortality in women with stage I-III breast cancer.

BACKGROUND: Prior evidence suggests a role for statins in the management of cancer. However, the benefit of statin use in the adjuvant setting remains uncertain. This study investigates associations between statin use initiated after a breast cancer diagnosis and mortality. METHODS: Women with stage I-III breast cancer were identified from the National Cancer Registry of Ireland (N=4243). Post-diagnostic statin initiators were identified from pharmacy claims data (N=837). Multivariate models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between de novo statin use and mortality. RESULTS: The median duration of statin use was 6.7 years. No association was found between post-diagnostic statin use and breast cancer-specific (HR 0.88, 95% CI 0.66, 1.17) or all-cause mortality (HR 1.00, 95% CI 0.82, 1.21). CONCLUSIONS: The results from our study suggest that initiating statin use after a diagnosis of stage I-III breast cancer is not associated with a reduction in breast cancer-specific mortality.

A novel mechanism of regulation of the anti-metastatic miR-31 by EMSY in breast cancer.

miR-31 is well known as an anti-metastatic microRNA (miRNA) in the context of breast cancer. However, to date the mechanism of regulation of this miRNA has yet to be elucidated. The recent publication by Viré et al. in Molecular Cell demonstrates for the first time that one mechanism of regulation of miR-31 is through the putative oncogene EMSY, whose amplification in breast cancer patients correlates with reduced expression of the miRNA. This regulation is dependent on the DNA-binding transcription factor ETS-1 which recruits EMSY and the histone demethylase KDM5B to the miR-31 promoter, thus repressing its transcription.

Peroxiredoxin-1 protects estrogen receptor α from oxidative stress-induced suppression and is a protein biomarker of favorable prognosis in breast cancer.

INTRODUCTION: Peroxiredoxin-1 (PRDX1) is a multifunctional protein, acting as a hydrogen peroxide (H2O2) scavenger, molecular chaperone and immune modulator. Although differential PRDX1 expression has been described in many tumors, the potential role of PRDX1 in breast cancer remains highly ambiguous. Using a comprehensive antibody-based proteomics approach, we interrogated PRDX1 protein as a putative biomarker in estrogen receptor (ER)-positive breast cancer. METHODS: An anti-PRDX1 antibody was validated in breast cancer cell lines using immunoblotting, immunohistochemistry and reverse phase protein array (RPPA) technology. PRDX1 protein expression was evaluated in two independent breast cancer cohorts, represented on a screening RPPA (n = 712) and a validation tissue microarray (n = 498). In vitro assays were performed exploring the functional contribution of PRDX1, with oxidative stress conditions mimicked via treatment with H2O2, peroxynitrite, or adenanthin, a PRDX1/2 inhibitor. RESULTS: In ER-positive cases, high PRDX1 protein expression is a biomarker of improved prognosis across both cohorts. In the validation cohort, high PRDX1 expression was an independent predictor of improved relapse-free survival (hazard ratio (HR) = 0.62, 95% confidence interval (CI) = 0.40 to 0.96, P = 0.032), breast cancer-specific survival (HR = 0.44, 95% CI = 0.24 to 0.79, P = 0.006) and overall survival (HR = 0.61, 95% CI = 0.44 to 0.85, P = 0.004). RPPA screening of cancer signaling proteins showed that ERα protein was upregulated in PRDX1 high tumors. Exogenous H2O2 treatment decreased ERα protein levels in ER-positive cells. PRDX1 knockdown further sensitized cells to H2O2- and peroxynitrite-mediated effects, whilst PRDX1 overexpression protected against this response. Inhibition of PRDX1/2 antioxidant activity with adenanthin dramatically reduced ERα levels in breast cancer cells. CONCLUSIONS: PRDX1 is shown to be an independent predictor of improved outcomes in ER-positive breast cancer. Through its antioxidant function, PRDX1 may prevent oxidative stress-mediated ERα loss, thereby potentially contributing to maintenance of an ER-positive phenotype in mammary tumors. These results for the first time imply a close connection between biological activity of PRDX1 and regulation of estrogen-mediated signaling in breast cancer.

Dynamic and influential interaction of cancer cells with normal epithelial cells in 3D culture.

BACKGROUND: The cancer microenvironment has a strong impact on the growth and dynamics of cancer cells. Conventional 2D culture systems, however, do not reflect in vivo conditions, impeding detailed studies of cancer cell dynamics. This work aims to establish a method to reveal the interaction of cancer and normal epithelial cells using 3D time-lapse. METHODS: GFP-labelled breast cancer cells, MDA-MB-231, were co-cultured with mCherry-labelled non-cancerous epithelial cells, MDCK, in a gel matrix. In the 3D culture, the epithelial cells establish a spherical morphology (epithelial sphere) thus providing cancer cells with accessibility to the basal surface of epithelia, similar to the in vivo condition. Cell movement was monitored using time-lapse analyses. Ultrastructural, immunocytochemical and protein expression analyses were also performed following the time-lapse study. RESULTS: In contrast to the 2D culture system, whereby most MDA-MB-231 cells exhibit spindle-shaped morphology as single cells, in the 3D culture the MDA-MB-231 cells were found to be single cells or else formed aggregates, both of which were motile. The single MDA-MB-231 cells exhibited both round and spindle shapes, with dynamic changes from one shape to the other, visible within a matter of hours. When co-cultured with epithelial cells, the MDA-MB-231 cells displayed a strong attraction to the epithelial spheres, and proceeded to surround and engulf the epithelial cell mass. The surrounded epithelial cells were eventually destroyed, becoming debris, and were taken into the MDA-MB-231 cells. However, when there was a relatively large population of normal epithelial cells, the MDA-MB-231 cells did not engulf the epithelial spheres effectively, despite repeated contacts. MDA-MB-231 cells co-cultured with a large number of normal epithelial cells showed reduced expression of monocarboxylate transporter-1, suggesting a change in the cell metabolism. A decreased level of gelatin-digesting ability as well as reduced production of matrix metaroproteinase-2 was also observed. CONCLUSIONS: This culture method is a powerful technique to investigate cancer cell dynamics and cellular changes in response to the microenvironment. The method can be useful for various aspects such as; different combinations of cancer and non-cancer cell types, addressing the organ-specific affinity of cancer cells to host cells, and monitoring the cellular response to anti-cancer drugs.

Analysis of cell free DNA to predict outcome to bevacizumab therapy in colorectal cancer patients.

To predict outcome to combination bevacizumab (BVZ) therapy, we employed cell-free DNA (cfDNA) to determine chromosomal instability (CIN), nucleosome footprints (NF) and methylation profiles in metastatic colorectal cancer (mCRC) patients. Low-coverage whole-genome sequencing (LC-WGS) was performed on matched tumor and plasma samples, collected from 74 mCRC patients from the AC-ANGIOPREDICT Phase II trial (NCT01822444), and analysed for CIN and NFs. A validation cohort of plasma samples from the University Medical Center Mannheim (UMM) was similarly profiled. 61 AC-ANGIOPREDICT plasma samples collected before and following BVZ treatment were selected for targeted methylation sequencing. Using cfDNA CIN profiles, AC-ANGIOPREDICT samples were subtyped with 92.3% accuracy into low and high CIN clusters, with good concordance observed between matched plasma and tumor. Improved survival was observed in CIN-high patients. Plasma-based CIN clustering was validated in the UMM cohort. Methylation profiling identified differences in CIN-low vs. CIN high (AUC = 0.87). Moreover, significant methylation score decreases following BVZ was associated with improved outcome (p = 0.013). Analysis of CIN, NFs and methylation profiles from cfDNA in plasma samples facilitates stratification into CIN clusters which inform patient response to treatment.

Identification of transcription factors associated with castration-resistance: is the serum responsive factor a potential therapeutic target?

BACKGROUND: Advanced prostate cancer is treated by hormone ablation therapy. However, despite an initial response, the majority of men relapse to develop castration-resistant disease for which there are no effective treatments. We have previously shown that manipulating individual proteins has only minor alterations on the resistant phenotype so we hypothesize that targeting the central transcription factors (TFs) would represent a better therapeutic approach. METHODS: We have undertaken a transcriptomic analysis of gene expression differences between the androgen-dependent LNCaP parental cells and its castration-resistant Abl and Hof sublines, revealing 1,660 genes associated with castration-resistance. Using effective bioinformatic techniques, these transcriptomic data were integrated with TF binding sites resulting in a list of TFs associated with the differential gene expression observed. RESULTS: Following validation of the gene-chip results, the serum response factor (SRF) was chosen for clinical validation and functional analysis due to its recent association with prostate cancer progression. SRF immunoreactivity in prostate tumor samples was shown for the first time to be associated with castration-resistance. SRF inhibition by siRNA and the small molecule inhibitor CCG-1423 resulted in decreased proliferation. CONCLUSION: SRF is a key TF by which resistant cells survive with depleted levels of androgens representing a target for therapeutic manipulation.

Complexation of histone deacetylase inhibitor belinostat to Cu(II) prevents premature metabolic inactivation in vitro and demonstrates potent anti-cancer activity in vitro and ex vivo in colon cancer.

PURPOSE: The histone deacetylase inhibitor (HDACi), belinostat, has had limited therapeutic impact in solid tumors, such as colon cancer, due to its poor metabolic stability. Here we evaluated a novel belinostat prodrug, copper-bis-belinostat (Cubisbel), in vitro and ex vivo, designed to overcome the pharmacokinetic challenges of belinostat. METHODS: The in vitro metabolism of each HDACi was evaluated in human liver microsomes (HLMs) using mass spectrometry. Next, the effect of belinostat and Cubisbel on cell growth, HDAC activity, apoptosis and cell cycle was assessed in three colon cancer cell lines. Gene expression alterations induced by both HDACis were determined using RNA-Seq, followed by in silico analysis to identify master regulators (MRs) of differentially expressed genes (DEGs). The effect of both HDACis on the viability of colon cancer patient-derived tumor organoids (PDTOs) was also examined. RESULTS: Belinostat and Cubisbel significantly reduced colon cancer cell growth mediated through HDAC inhibition and apoptosis induction. Interestingly, the in vitro half-life of Cubisbel was significantly longer than belinostat. Belinostat and its Cu derivative commonly dysregulated numerous signalling and metabolic pathways while genes downregulated by Cubisbel were potentially controlled by VEGFA, ERBB2 and DUSP2 MRs. Treatment of colon cancer PDTOs with the HDACis resulted in a significant reduction in cell viability and downregulation of stem cell and proliferation markers. CONCLUSIONS: Complexation of belinostat to Cu(II) does not alter the HDAC activity of belinostat, but instead significantly enhances its metabolic stability in vitro and targets anti-cancer pathways by perturbing key MRs in colon cancer. Complexation of HDACis to a metal ion might improve the efficacy of clinically used HDACis in patients with colon cancer.

Maternal and fetal cocaine- and amphetamine-regulated transcript in diabetic and non-diabetic pregnancy.

Cocaine- and amphetamine-regulated transcript (CART) is a leptin-regulated anorectic neuropeptide. Increased levels of leptin in cord blood of diabetic mothers have previously been described. The aim of this study was to quantify maternal and fetal serum CART levels in type 1 diabetes mellitus (T1DM, n = 10) and non-diabetic pregnancy (n = 10). Matched maternal serum samples (n = 20) were obtained at 36-weeks gestation and cord samples from the umbilical vein at delivery (n = 20), CART was quantified using a competitive enzyme immunoassay. Statistical analysis was performed using Spearmans correlation and t test. There was no difference in maternal CART levels at 36-weeks gestation between T1DM (mean = 331.13 pg/ml, Standard Error of the Mean (SEM) = 114.54) and non-diabetic pregnancy (mean = 195.01 pg/ml SEM = 29.37) (p = 0.106). Fetal CART levels in the umbilical vein were similar in T1DM (mean = 199.27 pg/ml, SEM = 39.81) and non-diabetic pregnancy (mean = 149.76 pg/ml, SEM = 26.08) (p = 0.143). Maternal serum CART levels measured at 36-weeks gestation correlated with maternal BMI at booking (Spearmans ρ = 0.332) (p = 0.001) irrespective of diabetes. Serum CART can be detected in both diabetic and non-diabetic human pregnancy and may play an important role in body mass regulation in pregnancy.

Master Transcription Regulators and Transcription Factors Regulate Immune-Associated Differences Between Patients of African and European Ancestry With Colorectal Cancer.

Background and Aims: Individuals of African (AFR) ancestry have a higher incidence of colorectal cancer (CRC) than those of European (EUR) ancestry and exhibit significant health disparities. Previous studies have noted differences in the tumor microenvironment between AFR and EUR patients with CRC. However, the molecular regulatory processes that underpin these immune differences remain largely unknown. Methods: Multiomics analysis was carried out for 55 AFR and 456 EUR patients with microsatellite-stable CRC using The Cancer Genome Atlas. We evaluated the tumor microenvironment by using gene expression and methylation data, transcription factor, and master transcriptional regulator analysis to identify the cell signaling pathways mediating the observed phenotypic differences. Results: We demonstrate that downregulated genes in AFR patients with CRC showed enrichment for canonical pathways, including chemokine signaling. Moreover, evaluation of the tumor microenvironment showed that cytotoxic lymphocytes and neutrophil cell populations are significantly decreased in AFR compared with EUR patients, suggesting AFR patients have an attenuated immune response. We further demonstrate that molecules called "master transcriptional regulators" (MTRs) play a critical role in regulating the expression of genes impacting key immune processes through an intricate signal transduction network mediated by disease-associated transcription factors (TFs). Furthermore, a core set of these MTRs and TFs showed a positive correlation with levels of cytotoxic lymphocytes and neutrophils across both AFR and EUR patients with CRC, thus suggesting their role in driving the immune infiltrate differences between the two ancestral groups. Conclusion: Our study provides an insight into the intricate regulatory landscape of MTRs and TFs that orchestrate the differences in the tumor microenvironment between patients with CRC of AFR and EUR ancestry.

Implementing subtype-specific pre-clinical models of breast cancer to study pre-treatment aspirin effects.

BACKGORUND: Prior data suggest pre-diagnostic aspirin use impacts breast tumour biology and patient outcome. Here, we employed faithful surgical resection models of HER2+ and triple-negative breast cancer (TNBC), to study outcome and response mechanisms across breast cancer subtypes. METHOD: NOD/SCID mice were implanted with HER2+ MDA-MB-231/LN/2-4/H2N, trastuzumab-resistant HER2+ HCC1954 or a TNBC patient-derived xenograft (PDX). A daily low-dose aspirin regimen commenced until primary tumours reached ~250 mm3 and subsequently resected. MDA-MB-231/LN/2-4/H2N mice were monitored for metastasis utilising imaging. To interrogate the survival benefit of pre-treatment aspirin, 3 weeks post-resection, HCC1954/TNBC animals received standard-of-care (SOC) chemotherapy for 6 weeks. Primary tumour response to aspirin was interrogated using immunohistochemistry. RESULTS: Aspirin delayed time to metastasis in MDA-MB-231/LN/2-4/H2N xenografts and decreased growth of HER2+ /TNBC primary tumours. Lymphangiogenic factors and lymph vessels number were decreased in HER2+ tumours. However, no survival benefit was seen in aspirin pre-treated animals (HCC1954/TNBC) that further received adjuvant SOC, compared with animals treated with SOC alone. In an effort to study mechanisms responsible for the observed reduction in lymphangiogenesis in HER2+ BC we utilised an in vitro co-culture system of HCC1954 tumour cells and mesenchymal stromal cells (MSC). Aspirin abrogated the secretion of VEGF-C in MSCs and also decreased the lymph/angiogenic potential of the MSCs and HCC1954 by tubule formation assay. Furthermore, aspirin decreased the secretion of uPA in HCC1954 cells potentially diminishing its metastatic capability. CONCLUSION: Our data employing clinically relevant models demonstrate that aspirin alters breast tumour biology. However, aspirin may not represent a robust chemo-preventative agent in the HER2+ or TNBC setting.

Tumor-specific HMG-CoA reductase expression in primary premenopausal breast cancer predicts response to tamoxifen.

INTRODUCTION: We previously reported an association between tumor-specific 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) expression and a good prognosis in breast cancer. Here, the predictive value of HMG-CoAR expression in relation to tamoxifen response was examined. METHODS: HMG-CoAR protein and RNA expression was analyzed in a cell line model of tamoxifen resistance using western blotting and PCR. HMG-CoAR mRNA expression was examined in 155 tamoxifen-treated breast tumors obtained from a previously published gene expression study (Cohort I). HMG-CoAR protein expression was examined in 422 stage II premenopausal breast cancer patients, who had previously participated in a randomized control trial comparing 2 years of tamoxifen with no systemic adjuvant treatment (Cohort II). Kaplan-Meier analysis and Cox proportional hazards modeling were used to estimate the risk of recurrence-free survival (RFS) and the effect of HMG-CoAR expression on tamoxifen response. RESULTS: HMG-CoAR protein and RNA expression were decreased in tamoxifen-resistant MCF7-LCC9 cells compared with their tamoxifen-sensitive parental cell line. HMG-CoAR mRNA expression was decreased in tumors that recurred following tamoxifen treatment (P < 0.001) and was an independent predictor of RFS in Cohort I (hazard ratio = 0.63, P = 0.009). In Cohort II, adjuvant tamoxifen increased RFS in HMG-CoAR-positive tumors (P = 0.008). Multivariate Cox regression analysis demonstrated that HMG-CoAR was an independent predictor of improved RFS in Cohort II (hazard ratio = 0.67, P = 0.010), and subset analysis revealed that this was maintained in estrogen receptor (ER)-positive patients (hazard ratio = 0.65, P = 0.029). Multivariate interaction analysis demonstrated a difference in tamoxifen efficacy relative to HMG-CoAR expression (P = 0.05). Analysis of tamoxifen response revealed that patients with ER-positive/HMG-CoAR tumors had a significant response to tamoxifen (P = 0.010) as well as patients with ER-positive or HMG-CoAR-positive tumors (P = 0.035). Stratification according to ER and HMG-CoAR status demonstrated that ER-positive/HMG-CoAR-positive tumors had an improved RFS compared with ER-positive/HMG-CoAR-negative tumors in the treatment arm (P = 0.033); this effect was lost in the control arm (P = 0.138), however, suggesting that HMG-CoAR predicts tamoxifen response. CONCLUSIONS: HMG-CoAR expression is a predictor of response to tamoxifen in both ER-positive and ER-negative disease. Premenopausal patients with tumors that express ER or HMG-CoAR respond to adjuvant tamoxifen.

Characterisation and manipulation of docetaxel resistant prostate cancer cell lines.

BACKGROUND: There is no effective treatment strategy for advanced castration-resistant prostate cancer. Although Docetaxel (Taxotere®) represents the most active chemotherapeutic agent it only gives a modest survival advantage with most patients eventually progressing because of inherent or acquired drug resistance. The aims of this study were to further investigate the mechanisms of resistance to Docetaxel. Three Docetaxel resistant sub-lines were generated and confirmed to be resistant to the apoptotic and anti-proliferative effects of increasing concentrations of Docetaxel. RESULTS: The resistant DU-145 R and 22RV1 R had expression of P-glycoprotein and its inhibition with Elacridar partially and totally reversed the resistant phenotype in the two cell lines respectively, which was not seen in the PC-3 resistant sublines. Resistance was also not mediated in the PC-3 cells by cellular senescence or autophagy but multiple changes in pro- and anti-apoptotic genes and proteins were demonstrated. Even though there were lower basal levels of NF-κB activity in the PC-3 D12 cells compared to the Parental PC-3, docetaxel induced higher NF-κB activity and IκB phosphorylation at 3 and 6 hours with only minor changes in the DU-145 cells. Inhibition of NF-κB with the BAY 11-7082 inhibitor reversed the resistance to Docetaxel. CONCLUSION: This study confirms that multiple mechanisms contribute to Docetaxel resistance and the central transcription factor NF-κB plays an immensely important role in determining docetaxel-resistance which may represent an appropriate therapeutic target.

A new effector pathway links ATM kinase with the DNA damage response.

The related kinases ATM (ataxia-telangiectasia mutated) and ATR (ataxia-telangiectasia and Rad3-related) phosphorylate a limited number of downstream protein targets in response to DNA damage. Here we report a new pathway in which ATM kinase signals the DNA damage response by targeting the transcriptional cofactor Strap. ATM phosphorylates Strap at a serine residue, stabilizing nuclear Strap and facilitating formation of a stress-responsive co-activator complex. Strap activity enhances p53 acetylation, and augments the response to DNA damage. Strap remains localized in the cytoplasm in cells derived from ataxia telangiectasia individuals with defective ATM, as well as in cells expressing a Strap mutant that cannot be phosphorylated by ATM. Targeting Strap to the nucleus reinstates protein stabilization and activates the DNA damage response. These results indicate that the nuclear accumulation of Strap is a critical regulator in the damage response, and argue that this function can be assigned to ATM through the DNA damage-dependent phosphorylation of Strap.