Browsing by Author "Steeg, Patricia S."

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    DNA Double-Strand Break Repair Genes and Oxidative Damage in Brain Metastasis of Breast Cancer
    (Oxford University Press) Woditschka, Stephan; Evans, Lynda; Duchnowska, Renata; Reed, L. Tiffany; Palmieri, Diane; Qian, Yongzhen; Badve, Sunil; Sledge, George; Gril, Brunilde; Aladjem, Mirit I.; Fu, Haiqing; Flores, Natasha M.; Gökmen-Polar, Yesim; Biernat, Wojciech; Szutowicz-Zielińska, Ewa; Mandat, Tomasz; Trojanowski, Tomasz; Och, Waldemar; Czartoryska-Arlukowicz, Bogumiła; Jassem, Jacek; Mitchell, James B.; Steeg, Patricia S.; Department of Medicine, IU School of Medicine
    Background Breast cancer frequently metastasizes to the brain, colonizing a neuro-inflammatory microenvironment. The molecular pathways facilitating this colonization remain poorly understood. Methods Expression profiling of 23 matched sets of human resected brain metastases and primary breast tumors by two-sided paired t test was performed to identify brain metastasis–specific genes. The implicated DNA repair genes BARD1 and RAD51 were modulated in human (MDA-MB-231-BR) and murine (4T1-BR) brain-tropic breast cancer cell lines by lentiviral transduction of cDNA or short hairpin RNA (shRNA) coding sequences. Their functional contribution to brain metastasis development was evaluated in mouse xenograft models (n = 10 mice per group). Results Human brain metastases overexpressed BARD1 and RAD51 compared with either matched primary tumors (1.74-fold, P < .001; 1.46-fold, P < .001, respectively) or unlinked systemic metastases (1.49-fold, P = .01; 1.44-fold, P = .008, respectively). Overexpression of either gene in MDA-MB-231-BR cells increased brain metastases by threefold to fourfold after intracardiac injections, but not lung metastases upon tail-vein injections. In 4T1-BR cells, shRNA-mediated RAD51 knockdown reduced brain metastases by 2.5-fold without affecting lung metastasis development. In vitro, BARD1- and RAD51-overexpressing cells showed reduced genomic instability but only exhibited growth and colonization phenotypes upon DNA damage induction. Reactive oxygen species were present in tumor cells and elevated in the metastatic neuro-inflammatory microenvironment and could provide an endogenous source of genotoxic stress. Tempol, a brain-permeable oxygen radical scavenger suppressed brain metastasis promotion induced by BARD1 and RAD51 overexpression. Conclusions BARD1 and RAD51 are frequently overexpressed in brain metastases from breast cancer and may constitute a mechanism to overcome reactive oxygen species–mediated genotoxic stress in the metastatic brain.
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    Identification and validation of genes with expression patterns inverse to multiple metastasis suppressor genes in breast cancer cell lines
    (Springer-Verlag, 2014-10) Marino, Natascia; Collins, Joshua W.; Shen, Changyu; Caplen, Natasha J.; Merchant, Anand S.; Gökmen-Polar, Yesim; Goswami, Chirayu P.; Hoshino, Takashi; Qian, Yongzhen; Sledge, George W.; Steeg, Patricia S.; Department of Pathology and Laboratory Medicine, IU School of Medicine
    Metastasis suppressor genes (MSGs) have contributed to an understanding of regulatory pathways unique to the lethal metastatic process. When re-expressed in experimental models, MSGs block cancer spread to, and colonization of distant sites without affecting primary tumor formation. Genes have been identified with expression patterns inverse to a single MSG, and found to encode functional, druggable signaling pathways. We now hypothesize that common signaling pathways mediate the effects of multiple MSGs. By gene expression profiling of human MCF7 breast carcinoma cells expressing a scrambled siRNA, or siRNAs to each of 19 validated MSGs (NME1, BRMS1, CD82, CDH1, CDH2, CDH11, CASP8, MAP2K4, MAP2K6, MAP2K7, MAPK14, GSN, ARHGDIB, AKAP12, DRG1, CD44, PEBP1, RRM1, KISS1), we identified genes whose expression was significantly opposite to at least five MSGs. Five genes were selected for further analysis: PDE5A, UGT1A, IL11RA, DNM3 and OAS1. After stable downregulation of each candidate gene in the aggressive human breast cancer cell line MDA-MB-231T, in vitro motility was significantly inhibited. Two stable clones downregulating PDE5A (phosphodiesterase 5A), an enzyme involved in the regulation of cGMP-specific signaling, exhibited no difference in cell proliferation, but reduced motility by 47 and 66 % compared to the empty vector-expressing cells (p = 0.01 and p = 0.005). In an experimental metastasis assay, two shPDE5A-MDA-MB-231T clones produced 47-62 % fewer lung metastases than shRNA-scramble expressing cells (p = 0.045 and p = 0.009 respectively). This study demonstrates that previously unrecognized genes are inversely related to the expression of multiple MSGs, contribute to aspects of metastasis, and may stand as novel therapeutic targets.
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    A phase II study of medroxyprogesterone acetate in patients with hormone receptor negative metastatic breast cancer: translational breast cancer research consortium trial 007
    (SpringerLink, 2014-11) Miller, Kathy D.; Althouse, Sandra K.; Nabell, Lisle; Rugo, Hope; Carey, Lisa; Kimmick, Gretchen; Jones, David R.; Merino, Maria J.; Steeg, Patricia S.; Medicine, School of Medicine
    Preclinical data suggest that medroxyprogesterone acetate (MPA) has both anti-metastatic and anti-angiogenic activity in the absence of hormone receptors (HR). This phase II trial assessed the activity of MPA alone or in combination with low-dose chemotherapy in patients with metastatic HR-negative breast cancer. Postmenopausal women with HR-negative disease were eligible if they had not received more than 3 chemotherapy regimens for metastatic disease. All patients were treated with MPA 1,000-1,500 mg/day orally; patients in cohort two also received low-dose oral cyclophosphamide and methotrexate (ldCM, 50 mg/day and 2.5 mg twice daily on Days 1 and 2 each week). Tissue and circulating biomarkers were assessed serially. The primary endpoint was clinical benefit response defined as objective response or stable disease >6 months. Thirty patients were enrolled (14 MPA monotherapy; 16 MPA + ldCM); median age was 55 (35-80); nearly all had visceral involvement. Despite dose escalation in 90 % of patients, only 17 (57 %) patients ever achieved MPA trough concentrations >50 ng/ml. One patient developed grade 4 renal failure in the setting of rapid disease progression and dehydration. There were no objective responses. One patient in each cohort (~7 %) had stable disease for > 6 months. Skin Nm23 expression increased after 4 weeks of MPA + ldCM, but there were no significant changes in TSP-1, PAI-1 antigen, or PAI-1 activity. MPA had limited activity and does not warrant further development in patients with HR-negative advanced breast cancer. Poor bioavailability limited exposure despite dose escalation.
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    Predicting early brain metastases based on clinicopathological factors and gene expression analysis in advanced HER2-positive breast cancer patients
    (Springer US, 2015-03) Duchnowska, Renata; Jassem, Jacek; Goswami, Chirayu Pankaj; Dundar, Murat; Gökmen-Polar, Yesim; Li, Lang; Woditschka, Stephan; Biernat, Wojciech; Sosińska-Mielcarek, Katarzyna; Czartoryska-Arłukowicz, Bogumiła; Radecka, Barbara; Tomasevic, Zorica; Stępniak, Piotr; Wojdan, Konrad; Sledge, George W. Jr.; Steeg, Patricia S.; Badve, Sunil; Department of Medical & Molecular Genetics, IU School of Medicine
    The overexpression or amplification of the human epidermal growth factor receptor 2 gene (HER2/neu) is associated with high risk of brain metastasis (BM). The identification of patients at highest immediate risk of BM could optimize screening and facilitate interventional trials. We performed gene expression analysis using complementary deoxyribonucleic acid-mediated annealing, selection, extension and ligation and real-time quantitative reverse transcription PCR (qRT-PCR) in primary tumor samples from two independent cohorts of advanced HER2 positive breast cancer patients. Additionally, we analyzed predictive relevance of clinicopathological factors in this series. Study group included discovery Cohort A (84 patients) and validation Cohort B (75 patients). The only independent variables associated with the development of early BM in both cohorts were the visceral location of first distant relapse [Cohort A: hazard ratio (HR) 7.4, 95 % CI 2.4–22.3; p < 0.001; Cohort B: HR 6.1, 95 % CI 1.5–25.6; p = 0.01] and the lack of trastuzumab administration in the metastatic setting (Cohort A: HR 5.0, 95 % CI 1.4–10.0; p = 0.009; Cohort B: HR 10.0, 95 % CI 2.0–100.0; p = 0.008). A profile including 13 genes was associated with early (≤36 months) symptomatic BM in the discovery cohort. This was refined by qRT-PCR to a 3-gene classifier (RAD51, HDGF, TPR) highly predictive of early BM (HR 5.3, 95 % CI 1.6–16.7; p = 0.005; multivariate analysis). However, predictive value of the classifier was not confirmed in the independent validation Cohort B. The presence of visceral metastases and the lack of trastuzumab administration in the metastatic setting apparently increase the likelihood of early BM in advanced HER2-positive breast cancer.