Expression of the stem cell marker ALDH1 in BRCA1 related breast cancer

Introduction The BRCA1 protein makes mammary stem cells differentiate into mature luminal and myoepithelial cells. If a BRCA1 mutation results in a differentiation block, an enlarged stem cell component might be present in the benign tissue of BRCA1 mutation carriers, and these mammary stem cells could be the origin of BRCA1 related breast cancer. Since ALDH1 is a marker of both mammary stem cells and breast cancer stem cells, we compared ALDH1 expression in malignant tissue of BRCA1 mutation carriers to non-carriers. Methods Forty-one BRCA1 related breast cancers and 41 age-matched sporadic breast cancers were immunohistochemically stained for ALDH1. Expression in epithelium and stroma was scored and compared. Results Epithelial (P=0.001) and peritumoral (P=0.001) ALDH1 expression was significantly higher in invasive BRCA1 related carcinomas compared to sporadic carcinomas. Intratumoral stromal ALDH1 expression was similarly high in both groups. ALDH1 tumor cell expression was an independent predictor of BRCA1 mutation status. Conclusion BRCA1 related breast cancers showed significantly more frequent epithelial ALDH1 expression, indicating that these hereditary tumors have an enlarged cancer stem cell component. Besides, (peritumoral) stromal ALDH1 expression was also more frequent in BRCA1 mutation carriers. ALDH1 may therefore be a diagnostic marker and a therapeutic target of BRCA1 related breast cancer

Lympho-vascular invasion in BRCA related breast cancer compared to sporadic controls

<p>Abstract</p> <p>Background</p> <p>Germline mutations in the BRCA1 gene predispose to the development of breast cancer, exhibiting a specific histological phenotype. Identification of possible hallmarks of these tumors is important for selecting patients for genetic screening and provides inside in carcinogenetic pathways.</p> <p>Since BRCA1-associated breast cancers have pushing borders that prevent them from easily reaching vessels and are often of the medullary (like) type that is known to have a low rate of lympho-vascular invasion (LVI), we hypothesized that absence of LVI could characterize BRCA1 related breast cancer.</p> <p>Methods</p> <p>A population of 68 BRCA1 related invasive breast cancers was evaluated for LVI by an experienced breast pathologist blinded to mutation status, and compared to a control group matched for age, grade and tumor type.</p> <p>Results</p> <p>LVI was present in 25.0% of BRCA1 related cases, compared to 20.6% of controls (P = 0.54, OR = 1.29, CI 0.58-2.78).</p> <p>Conclusion</p> <p>LVI is frequent in BRCA1 germline mutation related breast cancers, but seems to occur as often in sporadic controls matched for age, grade and tumor type. Apparently, these hereditary cancers find their way to the blood and lymph vessels despite their well demarcation and often medullary differentiation.</p

DDX3 in cancer : Identifying motives, targets and partners in crime

The protein DDX3 is a member of the DEAD box family of RNA helicases, which have the ability to unwind complex RNA secondary structures and hereby facilitate RNA related cellular processes, like mRNA translation. DDX3 is a DEAD box RNA helicase that plays an oncogenic role in several cancer subtypes. RK-33 is developed as a small molecule inhibitor of DDX3. In this thesis we evaluate different aspects of DDX3 and the effect of inhibition with RK-33 in cancer cells. First, we studied why cancer cells are dependent on DDX3 for performing oncogenic tasks by using (phospho-)proteomics. We found that DDX3 inhibition reduces mitochondrial translation activity in cancer cells, which is increasingly recognized as a viable target for anti-cancer therapeutics. The mitochondria have their own translational machinery for synthesis of oxidative phosphorylation proteins. Interestingly, recent studies have shown that irradiated cancer cells increase oxidative phosphorylation to facilitate DNA repair and hereby induce resistance to radiation therapy. We found RK-33 to antagonize the increase in oxygen consumption and ATP production observed after exposure to ionizing radiation, and to reduce DNA repair in breast cancer cells. Our results explain the selective anti-cancer activity observed after RK-33 treatment, especially in combination with radiation therapy, and put inhibition of mitochondrial translation forward as a novel radiosensitization strategy. In addition, RK-33 was found to sensitize cells to treatment with PARP inhibitors. Next, we evaluated DDX3 sensitivity in different (sub)types of cancer. DDX3 inhibition reduces oncogenic Wnt-signaling and DDX3 seems to be a promising therapeutic target in a subset of colorectal cancers. DDX3 expression is also upregulated in breast cancer metastases, when compared to the corresponding primary tumor. In addition, we found that both cytoplasmic and nuclear DDX3 expression of the tumor correlate with shorter survival of breast and colorectal cancer patients, suggesting that they may serve as biomarkers to select patients that would benefit most from DDX3 inhibition. Last, we put DDX3 inhibitors in a broader perspective by reviewing the literature on the all DEAD/H box RNA helicase family members as potential therapeutic targets in oncogenic mRNA translation. Overall we conclude that DDX3 inhibition can be a promising therapeutic strategy in cancer cells

DDX3 in cancer : Identifying motives, targets and partners in crime

The protein DDX3 is a member of the DEAD box family of RNA helicases, which have the ability to unwind complex RNA secondary structures and hereby facilitate RNA related cellular processes, like mRNA translation. DDX3 is a DEAD box RNA helicase that plays an oncogenic role in several cancer subtypes. RK-33 is developed as a small molecule inhibitor of DDX3. In this thesis we evaluate different aspects of DDX3 and the effect of inhibition with RK-33 in cancer cells. First, we studied why cancer cells are dependent on DDX3 for performing oncogenic tasks by using (phospho-)proteomics. We found that DDX3 inhibition reduces mitochondrial translation activity in cancer cells, which is increasingly recognized as a viable target for anti-cancer therapeutics. The mitochondria have their own translational machinery for synthesis of oxidative phosphorylation proteins. Interestingly, recent studies have shown that irradiated cancer cells increase oxidative phosphorylation to facilitate DNA repair and hereby induce resistance to radiation therapy. We found RK-33 to antagonize the increase in oxygen consumption and ATP production observed after exposure to ionizing radiation, and to reduce DNA repair in breast cancer cells. Our results explain the selective anti-cancer activity observed after RK-33 treatment, especially in combination with radiation therapy, and put inhibition of mitochondrial translation forward as a novel radiosensitization strategy. In addition, RK-33 was found to sensitize cells to treatment with PARP inhibitors. Next, we evaluated DDX3 sensitivity in different (sub)types of cancer. DDX3 inhibition reduces oncogenic Wnt-signaling and DDX3 seems to be a promising therapeutic target in a subset of colorectal cancers. DDX3 expression is also upregulated in breast cancer metastases, when compared to the corresponding primary tumor. In addition, we found that both cytoplasmic and nuclear DDX3 expression of the tumor correlate with shorter survival of breast and colorectal cancer patients, suggesting that they may serve as biomarkers to select patients that would benefit most from DDX3 inhibition. Last, we put DDX3 inhibitors in a broader perspective by reviewing the literature on the all DEAD/H box RNA helicase family members as potential therapeutic targets in oncogenic mRNA translation. Overall we conclude that DDX3 inhibition can be a promising therapeutic strategy in cancer cells

Nuclear DDX3 expression predicts poor outcome in colorectal and breast cancer

Marise R Heerma van Voss,1,2 Farhad Vesuna,2 Guus M Bol,1,2 Jan Meeldijk,1,3 Ana Raman,4 G Johan Offerhaus,1 Horst Buerger,5 Arvind H Patel,6 Elsken van der Wall,7,8 Paul J van Diest,1,8 Venu Raman1,2,8 1Department of Pathology, University Medical Center Utrecht, Utrecht, the Netherlands; 2Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 3Laboratory of Translational Immunology, University Medical Center Utrecht, Utrecht, the Netherlands; 4Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 5Institute of Pathology, Paderborn, Germany; 6Centre for Virus Research, MRC-University of Glasgow, Glasgow, UK; 7Cancer Center, University Medical Center Utrecht, Utrecht, the Netherlands; 8Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA Purpose: DEAD box protein 3 (DDX3) is an RNA helicase with oncogenic properties that shuttles between the cytoplasm and nucleus. The majority of DDX3 is found in the cytoplasm, but a subset of tumors has distinct nuclear DDX3 localization of yet unknown biological significance. This study aimed to evaluate the significance of and mechanisms behind nuclear DDX3 expression in colorectal and breast cancer.Methods: Expression of nuclear DDX3 and the nuclear exporter chromosome region maintenance 1 (CRM1) was evaluated by immunohistochemistry in 304 colorectal and 292 breast cancer patient samples. Correlations between the subcellular localization of DDX3 and CRM1 and the difference in overall survival between patients with and without nuclear DDX3 were studied. In addition, DDX3 mutants were created for in vitro evaluation of the mechanism behind nuclear retention of DDX3.Results: DDX3 was present in the nucleus of 35% of colorectal and 48% of breast cancer patient samples and was particularly strong in the nucleolus. Nuclear DDX3 correlated with worse overall survival in both colorectal (hazard ratio [HR] 2.34, P&lt;0.001) and breast cancer (HR 2.39, P=0.004) patients. Colorectal cancers with nuclear DDX3 expression more often had cytoplasmic expression of the nuclear exporter CRM1 (relative risk 1.67, P=0.04). In vitro analysis of DDX3 deletion mutants demonstrated that CRM1-mediated export was most dependent on the N-terminal nuclear export signal.Conclusion: Overall, we conclude that nuclear DDX3 is partially CRM1-mediated and predicts worse survival in colorectal and breast cancer patients, putting it forward as a target for therapeutic intervention with DDX3 inhibitors under development in these cancer types. Keywords: RNA helicase, DDX3X, nuclear export, CRM