Browsing by Subject "Breast Cancer"

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Antibody Conjugated Nanoparticles for Targeting Metastatic Triple Negative Breast Cancer
(2016-09) Khanna, Vidhi Devendra
Early detection and the availability of new treatments have improved the survival rates of patients presenting with local or regional breast cancer to as high as 99% and 85%, respectively. On the contrary, patients with metastatic disease have a dismal 5-year survival rate of 17%.1 Thus, there is an urgent need for treatment strategies directed towards metastasis. Our lab has developed antibodies (Clone 6 and AM6) capable of recognizing tumor cells that have undergone epithelial-to-mesenchymal transition (EMT), a key step in the generation of circulating tumor cells and metastasis. The goal of the current study was to determine whether we use these antibodies as targeting ligands for directing anticancer drug-loaded polymeric nanoparticles to metastatic triple negative breast cancer cells as a novel therapeutic option. Polymeric PLGA nanoparticles loaded with paclitaxel, a chemotherapeutic agent, were functionalized with the antibodies using thiol-maleimide chemistry. We optimized the conjugation reaction in order to achieve maximal cell uptake of nanoparticles without compromising antibody binding. In vitro studies were carried out in an MDA-MB-231 derivative cell line with enhanced lung metastatic potential as well as a melanoma metastatic cell line M12. Clone 6 nanoparticles and AM6 nanoparticles showed significant improvement in cellular uptake as well as retention. A competition experiment confirmed target-mediated uptake of nanoparticles. Cytotoxicity studies showed improved cell kill using Clone 6 nanoparticles and AM6 nanoparticles. Based on these promising in vitro results, we are currently carrying out in vivo studies in mice. The development of a targeted drug delivery system for the treatment of metastatic triple negative breast cancer can significantly enhance the survival rate for patients who often times have a life-expectancy of less than one year.2
Biosynthetic and Energetic Lethality of Targeting Metabolic Plasticity for Cancer Treatment
(2020-08) Ronayne, Conor
Solid tumors are composed of numerous heterogeneous tissue types with a diverse molecular pathology. Uncontrolled replication and division, along with nutrient and oxygen gradients across the tumor, dictate dynamic intratumoral phenotypes that are reinforced by molecular hallmarks of cancer; largely shaping modern clinical treatment regimens. Importantly, deregulated energetics and reprogrammed tumor metabolism enable constitutive growth in challenging microenvironments. The ability of malignant cells to switch between numerous metabolic phenotypes (metabolic plasticity) allows for the generation of energy, appropriation of biosynthetic building blocks, and control of redox equilibrium. Hence, therapeutic targeting of metabolic plasticity with small molecules holds promise as a novel and enduring therapeutic strategy. In this regard, the current thesis work describes efforts toward developing novel small molecule mitochondrial pyruvate carrier inhibitors to induce bioenergetic and synthetic lethality in cancer cells.
Development of 2-(alkoxycarbonyl)-allyl esters as anticancer agents
(2018-01) Ronayne, Conor
Cancer is the second leading cause of human mortality in the United States, with the standard treatment options being surgery, cytotoxic chemotherapy, and radiation therapy. Recently, there has been strong emphasis in developing targeted small molecule therapies which has led to the development of numerous anticancer drugs. However, many of the current cancer chemotherapeutic options are burdened with toxicity and treatment resistance and hence novel therapies with reduced side effects are urgently needed. In the current work, a structurally diverse library of Baylis-Hillman reaction derived 2-(alkoxycarbonyl)-allyl esters have been synthesized, evaluated for their in vitro cell proliferation inhibition properties, in vitro cellular and molecular mechanisms of action, in vivo systemic toxicity study in CD-1 mice, and in vivo anticancer efficacy study in a triple negative breast cancer MDA-MB-231 xenograft model in NOD SCID mice. Several of the synthesized compounds exhibit promising in vitro anticancer properties. Further, the lead candidate compound is well tolerated in healthy mice as indicated by normal body weight changes, and exhibits similar if not slightly better tumor growth inhibition properties than clinically available cancer drug doxorubicin.
Effect of N1-hexyl-N5-benzyl-biguanide mesylate (HBB) on Immediate Early Hormonal Signaling in MCF-7 Breast Cancer Cells
(2016) Ji, Michelle, M
HBB is a chemical compound being tested as a possible drug to treat breast cancer in addition to other hormone therapies. However, its mechanism remains unclear. This set of experiments was done to understand how HBB treated cells react upon exposure to either estradiol or progesterone. By using western blot assays, it was determined that phosphorylated ERK levels increased in cells treated with HBB.
Factors affecting treatment choice in HER2 positive metastatic breast cancer.
(2009-03) Gallagher, Eva
Women with HER2 positive breast cancer have decreased overall survival and may have a poorer response to treatment. Evidence suggests that disparities exist in treatment and outcomes in individuals with diverse racial and ethnic backgrounds, the elderly, individuals that are obese, hormone receptor positive, those with comorbid conditions, those treated in various regions of the country, and in different treatment settings. Trastuzumab (Herceptin®) is an anti-HER2 monoclonal antibody and was the first targeted therapy developed for the treatment of HER2 positive metastatic breast cancer. With its approval by the U.S. Federal Drug Administration in 1998, trastuzumab became the standard of care for treatment of HER2 positive MBC. This study examined differences in treatment, specifically trastuzumab use, and outcomes in these various groups treated for HER2 positive metastatic breast cancer. A conceptual framework guided by the fourth version of Andersen's health service utilization model was developed to better understand treatment patterns in these various groups. A prospective observational database called RegistHER was the source of the data. The first outcome evaluated was whether the frequency of use of optimal therapy (antibody) varied by group. Using logistic regression, this study showed no difference in use of optimal treatment in participants based on region of the country, race, obesity status or comorbid conditions. Differences in these groups might be seen given larger sample sizes. There were differences seen in individuals treated in different settings, the elderly, and those in that are ER/PR positive. Although women who are hormone receptor positive are eligible for treatment with hormones, consideration should be given to concurrent or sequential treatment with antibody therapy in those women that are HER2 positive. The second outcome evaluated was the time to start of treatment (in days). Logistic regression showed no variables were significant for this outcome indicating that race, age, obesity status, treatment setting, region of the country, hormone receptor status, the presence of cardiac disease and comorbid conditions did not affect time to start of treatment in this sample of patients from the RegistHER database. The third outcome evaluated was time to progression of disease. Using Cox regression, those who were ER/PR positive had a reduced risk of having progressive disease than their ER/PR negative counterparts. Not surprisingly, those with ER/PR positive disease did better than those that were ER/PR negative since those that have HR negative disease typically have a poorer prognosis than their HR positive counterparts. An unplanned sub-analysis showed that when you look at just those that are HR positive and compare those who got antibody to those that did not get antibody, both groups progressed at about the same rate. RegistHER, a registry with the largest cohort of HER2 positive MBC patients followed to date, is important because it provides a unique opportunity to characterize treatment patterns in this subset of individuals with breast cancer. In this evaluation of the database, important information regarding use of optimal treatment and time to progressive disease for women with HER2- positive breast cancer was described. Given the findings, this additional data may guide clinical decision-making for healthcare providers and their HER2 positive breast cancer patients and ultimately improve outcomes.
Follow-up Care After Breast Cancer
(2009-05-06) Harris, Donald G.
Women who have been treated for Stage I, II, or III breast cancer who are asymptomatic should receive follow-up care consisting of regular doctor’s visits and mammograms. Further testing, such as chest x-rays or blood tests, are not appropriate for routine follow-up and do not provide any survivorship benefit.
High-throughput Screening and Chemical Synthesis for the Discovery of APOBEC3 DNA Cytosine Deaminase Inhibitors
(2015-09) Olson, Margaret
APOBEC3 (APOBEC3A-APOBEC3H) enzymes catalyze single-stranded (ss)DNA cytosine-to-uracil (C-to-U) deamination as a function of innate immune defense against foreign DNA. Host cellular protection results from APOBEC3-catalyzed lethal mutagenesis of the offending genome. When misregulated, however, APOBEC3 enzymes have been demonstrated to drive the genetic evolution of numerous cancers and HIV-1. Specifically, sub-lethal levels of APOBEC3D/F/G/H-catalyzed mutation can enable HIV-1 escape from immune defense and antiretroviral therapies. Moreover, APOBEC3B over-expression in breast, bladder, cervical, lung, and head/neck cancers generates high levels of C-to-U mutation, which drives tumor formation, metastasis, and chemotherapeutic resistance. Thus, small molecule inhibition of APOBEC3-catalyzed deamination may provide a novel strategy for HIV-1 and cancer drug development. This thesis highlights efforts to discover small molecule inhibitors of the APOBEC3s through high-throughput screening (HTS) and chemical synthesis. Chapter 2 discusses an HTS of 168,192 compounds against APOBEC3B and APOBEC3G. In this effort, MN23 was discovered as a potent inhibitor of APOBEC3B (IC50 = 150 nM) and APOBEC3G (IC50 = 5.5 µM). Chapter 2 also reports a novel synthesis of MN23, and preliminary efforts to elucidate its mechanism of inhibition. Chapter 3 presents a class of covalent APOBEC3G-specific inhibitors based on a 1,2,4-triazole-3-thiol substructure. This compound class is predicted to inhibit APOBEC3G by covalently binding C321, forcing an inhibitory conformational change within the enzyme active site. Chapter 4 reports the discovery of a novel APOBEC3G inhibitory chemotype, which was discovered from the deconvolution of an impure HTS hit. In this effort, we also identified a previously unreported Pan Assay Interference Scaffold (PAINS), and characterized the mechanism by which compounds of this class undergo oxidative decomposition. Finally, Chapter 5 describes how benzthiazolinone-based APOBEC3 inhibitors are being developed into probes of APOBEC3 structure and function. Brief descriptions of two unrelated projects performed concurrent with these studies are also detailed in the Appendices.
Identification of Putative Fatty Acid Binding Protein 4 Receptors on Breast Cancer Epithelial Cells
(2023-05) Chen, Dongmei
Fatty acid binding protein 4 (FABP4) is a small 15-kDa cytoplasmic lipid carrier protein regulating fatty acid trafficking and metabolism. It is one of the most abundant proteins in mature adipocytes and can be secreted into the extracellular environment upon lipolytic stimulus, functioning as an adipokine. Elevated circulating FABP4 levels have been associated with obesity-related and inflammation-related diseases. Recent studies have indicated FABPP4 as a potential biomarker in cancer diagnosis and prognosis. FABP4 upregulation or exogenous FABP4 (eFABP4) administration has been found to promote cancer growth, invasion and metastasis, while FABP4 inhibition reduced cancer progression. Understanding the molecular mechanism underlying FABP4 effects in cancer is critical for developing anticancer drugs. Although exogenous FABP4 has been found to exert pro-tumorigenic effects, there is no known FABP4 receptor that transduces its signaling into intracellular responses. Identifying a FABP4 receptor would be significant for targeting FABP4 in cancers. Furthermore, although fatty acids have been found to be essential in FABP4 function, the mechanisms explaining their collaboration remain largely unknown. This thesis aims to identify putative FABP4 receptors on cancer cell plasma membrane to understand FABP4 signaling in breast cancer cells. Our work reveals that eFABP4 binds to the extracellular domain of desmoglein 2 to mediate breast cancer epithelial cell growth via an ERK-NRF2 axis, suggesting desmoglein 2 as a FABP4 receptor. We also find that fatty acids enhance the interaction between FABP4 and desmoglein 2, which may explain why non-fatty acid binding mutants of FABP4 abolish FABP4 effects and support the role of fatty acids in FABP4 signaling. In conclusion, our findings provide new insights into the mechanism of FABP4 in the development and progression of obesity-associated cancers.
Post-translationally Modified Glucocorticoid Receptors and Protein Tyrosine Kinase 6 Modulate Triple Negative Breast Cancer Phenotypes
(2020-07) Perez Kerkvliet, Carlos
Triple negative breast cancer (TNBC) is the most metastatic and deadly breast cancer subtype, accounting for 20-30% of all breast cancer cases. There is a critical need to identify molecular targets that could be exploited as new biomarkers of TNBC prognosis and for improving therapies. Although TNBC lacks estrogen and progesterone receptors, 15-40% of TNBC patients express the glucocorticoid receptor (GR). Women with TNBC that express high levels of GR have poor outcomes. We hypothesize that GR is a key mediator of advanced cancer phenotypes in TNBC. Altered signaling pathways typify breast cancer and serve as direct inputs to steroid hormone receptor “sensors.” We previously reported that phospho-Ser134-GR (pS134-GR) species are elevated in TNBC and cooperate with hypoxia-inducible factors, providing a novel avenue for activation of GR in response to local or cellular stress. Specifically, we propose that GR acts as a “sensor” for stress signaling pathways commonly activated by soluble factors that are abundant within the tumor microenvironment (TME) of TNBC. Herein, we show that in the absence of GR ligands, GR is transcriptionally activated via p38-dependent phosphorylation of Ser134 as a mechanism of homeostatic stress-sensing and regulated upon exposure of TNBC cells to TME-derived agents. The ligand-independent pS134-GR transcriptome encompasses Transforming Growth Factor β1 (TGFβ1) and Mitogen Activated Protein Kinase (MAPK) signaling gene sets associated with TNBC cell survival and migration/invasion. Accordingly, pS134-GR was essential for TNBC cell anchorage-independent growth in soft-agar, migration, invasion, and tumorsphere formation, an in vitro readout of cancer stemness properties. Both pS134-GR and expression of the MAPK-scaffolding molecule 14-3-3ζ were essential for a functionally intact p38 MAPK signaling pathway downstream of MAP3K5/ASK1, indicative of a feed-forward signaling loop wherein self-perpetuated GR phosphorylation enables cancer cell autonomy. A 24-gene pS134-GR-dependent signature induced by TGFβ1 predicts shortened overall survival in breast cancer patients. Additionally, GR is known to induce the expression of PTK6, a soluble protein tyrosine kinase important in mediating signaling in response to cellular stress. PTK6 is overexpressed in 86% of breast cancer patients, regardless of subtypes. Although GR is known to modulate PTK6 expression in TNBC, PTK6-driven signaling events in the context of TNBC are largely undefined. We sought to delineate the functions of downstream of PTK6. To do this, we created kinase-dead (KM) and kinase-intact domain structure mutants of PTK6 via in frame deletions of the N-terminal SH3 or SH2 domains. While the PTK6 kinase domain contributed to soft-agar colony formation, PTK6 kinase activity was entirely dispensable for cell migration. Specifically, TNBC models expressing a PTK6 variant lacking the SH2 domain (SH2-del PTK6) were unresponsive to growth factor-stimulated cell motility relative to SH3-del, KM or wild-type PTK6 controls. Reverse phase protein array revealed that the SH2 domain of PTK6 mediates TNBC cell motility via activation of the RhoA and/or AhR signaling pathways. Inhibition of RhoA and/or AhR blocked TNBC cell migration as well as the branching/invasive morphology of PTK6+/AhR+ primary breast tumor tissue organoids. The combination of AhR and Rho inhibitors enhanced paclitaxel cytotoxicity in TNBC cells, including a taxane-refractory TNBC model. In conclusion, our results identified pS134-GR as a critical downstream effector of p38 MAPK signaling and TNBC migration/invasion, survival, and stemness properties. Our studies define a ligand-independent role for GR as a homeostatic “sensor” of intrinsic stimuli as well as extrinsic factors rich within the TME (TGFβ1) that enables potent activation of the p38 MAPK stress-sensing pathway and nominate pS134-GR as a therapeutic target in aggressive TNBC. Additionally, we identified that PTK6 (SH2-domain), a downstream gene of GR, is a potent effector of advanced cancer phenotypes in TNBC. We identified both RhoA and AhR as novel therapeutic targets in PTK6+ breast tumors since these two proteins are downstream effectors of PTK6 functions in TNBC.
Postoperative Radiotherapy Breast Cancer Treatment: Musculoskeletal and Functional Implications
(2023-09) Braudy, Renata
ABSTRACT Purpose/Hypotheses: The overall purpose of this study was to better understand the effect of post-lumpectomy radiation therapy (RT) on skeletal muscle morphology, shoulder kinematics, and shoulder function following treatment for unilateral breast cancer. We hypothesized that within the same breast cancer survivor, the affected (treated) side would demonstrate significantly different shoulder kinematics and skeletal muscle morphology than the unaffected (untreated) side. We also hypothesized that RT dose delivered to specific muscles within the radiation field would adversely affect self-reported shoulder function. A small study was first performed on healthy volunteers to determine intra-rater reliability of a novel method of skeletal muscle B-mode ultrasonography (US) to evaluate echo intensity (EI) and cross-sectional area (CSA) of three muscles within the radiation field that have the potential to affect shoulder function. Number of Participants: 31 (5 healthy volunteers for US reliability, 26 breast cancer survivors for main study) Materials and Methods: This was a single center, non-therapeutic, observational cross-sectional study with two parts. First, 5 healthy volunteers participated in the US reliability study which involved three repeated measures of the pectoralis major (PMaj), pectoralis minor (PMin), and serratus anterior (SA) bilaterally. Second, 26 breast cancer survivors who were at least 1-year post-completion of RT following lumpectomy plus sentinel lymph node biopsy for the treatment of unilateral breast cancer then participated in the main study. Three-dimensional kinematic data were collected using electromagnetic sensors during forward shoulder flexion and abduction. Musculoskeletal US was used to determine skeletal muscle CSA and EI of the PMaj, PMin, and SA muscles of the treated and untreated sides. Radiation dose analyses were performed for those same 3 muscles using pre-existing computed tomography radiation simulation scans. The Penn Shoulder Score (PSS) and a custom questionnaire were also given to participants. Data were analyzed using Wilcoxon rank sum tests to determine difference across sides and groups, Spearman correlation to examine associations between variables, and multiple linear regression to examine covariate effects. Ultrasound intrarater reliability was performed on the healthy participants using intraclass correlation coefficient (ICC) analysis. Statistical significance cutoff value was set at 0.05 for all tests. Results: PMaj and PMin CSA and EI were reliable (ICC > 0.70) and used in the breast cancer survivor study. SA CSA and EI were not reliable (ICC < 0.7) and were used in the main study as exploratory analyses only. Breast cancer survivors demonstrated more sternoclavicular elevation during arm elevation on their affected side vs. their unaffected side. No significant differences existed between the affected and unaffected sides for other shoulder kinematic variables nor for ultrasound EI and CSA. In general, Penn Shoulder Score values were high, but a few specific functional movements were more commonly noted as being difficult which has clinical implications. Some PMin, PMaj, and SA radiation values were significantly correlated with multiple aspects of the PSS (total score and subscales). Trends were found for the PMin radiation dose and total radiation dose to affect the PSS, although correction for multiple testing made these statistically insignificant. Conclusions: Our data suggests that there may be a significant effect of postoperative RT on shoulder function in breast cancer survivors after unilateral lumpectomy and sentinel lymph node biopsy. Kinematic analysis demonstrated increased clavicle elevation on the affected side vs the unaffected side during arm elevation, but clinical relevance is uncertain. B-mode US was a reliable method of quantifying PMaj and PMin CSA and EI, but it was not reliable for the SA. B-mode US may not be sensitive enough to detect significant differences in EI and CSA in these muscles following RT. The PMaj, PMin, and SA receive a significant amount of radiation during treatment which may affect patient-reported shoulder pain. Although PSS scores were generally high, participants consistently reported ‘some difficulty’ with certain functional tasks that highlight the specific impairments many breast cancer survivors have following treatment. Additionally, breast cancer survivors complained not just of ‘shoulder pain’ but also stiffness, tightness, achiness, and other impairments in their shoulder, chest wall, and arm that need to be recognized and addressed by medical providers. This research demonstrates potential relationships between adjuvant RT and shoulder function which need to be further investigated to provide breast cancer survivors with the highest quality of life possible.
Progesterone Receptor Isoform Signaling In Ovarian Cancer Cellular Senescence
(2015-08) Campion, Caroline
As the deadliest of all gynecologic malignancies, ovarian cancer has a death rate of more than 50% due to late detection and diagnosis of the disease and intrinsic or acquired resistance to current therapeutic regimens. The identification of robust biomarkers for early detection will have a substantial impact on survival rates, while prognostic molecular markers may allow for efficacious targeted therapeutic strategies. Progesterone plays a pivotal role in the development and progression of hormone-regulated tumors. In the breast, progesterone promotes a proliferative, pro-survival response, but inhibits growth in the uterus and ovary. The opposing biology in ovarian versus breast cancer cells may be largely dependent on cell context. The paradoxical effects of progesterone observed in ovarian relative to breast cancer cells may be attributed to actions of the nuclear progesterone receptor (PR) and its isoforms, PR-B and PR-A and their relative regulation (i.e. by post-translational modifications and co-factor binding partners), differential cross-talk between PR and growth factor-mediated signaling pathways (i.e. protein kinases), and/or altered expression levels in the target cells. In contrast to breast cancer, the detailed mechanisms of progesterone action in ovarian cancer are poorly understood. The goals of our studies were to determine the level of PR isoform expression in primary and cell models of ovarian cancer, to define the biological consequences of PR expression and activity on ovarian cancer cell biology, and to identify the key cofactor(s) required for mediating PR-dependent signaling actions. We demonstrated that ligand-activated PR-B induced a non-proliferative cell fate, known as cellular senescence, through a FOXO1-dependent mechanism in ovarian cancer cells. PR-B and FOXO1 were co-recruited to the same PRE-containing region of the upstream promoter of p21 upon progestin (R5020) treatment. Both proteins are required to cooperatively activate p21 expression based on data from PR-null control cells and lentiviral-delivered shRNA FOXO1-knockdown studies. Stable knock-down of FOXO1 inhibited progestin-induced p21 expression in ES-2 cells stably expressing GFP-tagged PR-B and blocked PR-dependent cellular senescence. Next, we investigated the biological consequences of PR isoform-specific gene regulation in ovarian cancer models, as well as directly compared PR isoform-selective transcriptomes between ovarian and breast cancer models. In ovarian cancer cells, PR-A is relatively insensitive to hormone, and PR-B (but not PR-A) is capable of inducing FOXO1 and p21 expression required for progestin-mediated cellular senescence in ovarian cancer cells. Furthermore, our studies revealed FOXO1 as a critical cofactor and determinant for the regulation of PR hormone sensitivity. Namely, activated FOXO1 confers PR-B-like behavior to PR-A, and in the presence of FOXO1, PR-A trans-activates classical PR-B target genes and induces robust cellular senescence. Finally, we utilized a novel ex vivo explant culture system of human primary ovarian tumors that recapitulated our in vitro findings. Significantly, identifying the mechanisms governing PR-A versus PR-B specific gene regulation driven by FOXO1 may provide a means to promote PR-B driven cellular senescence in ovarian cancer and provide clues to inducing the protective actions of PR-A in other hormone-driven cancers, such as breast and uterine. PR-targeted strategies could provide a safe and useful means to improve treatment outcomes and increase overall ovarian cancer patient survival.
Regulation of breast tumor Kinase (Brk/PTK6) downstream of Met receptor signaling leads to breast cancer cell migration.
(2010-08) Castro, Nancy Elizabeth
Protein tyrosine kinases (PTKs) play a critical role in the regulation of normal cell growth and differentiation and contribute to neoplastic transformation. Breast tumor kinase (Brk/PTK6) is a non-receptor or "soluble" tyrosine kinase that was cloned from a human metastatic breast tumor and found to be overexpressed in a majority (86%) of human breast tumors and cell lines. While Brk is abundant in normal differentiating epithelial cells of the GI tract and skin, it is essentially absent from normal mammary epithelial or stromal cell compartments. We hypothesize that Brk expression contributes to breast cancer progression. Previous studies in the Lange lab identified the importance of the ErbB ligand, heregulin-β1, in activating Brk kinase activity downstream of rac-1 and upstream of ERK5 and p38 MAP kinases. Stable knockdown of Brk decreased heregulin-β1-induced activation of ERK5 and p38 MAP kinases. Thus, indicating the requirement for Brk in breast cancer cell migration downstream of Her2/Her3 signaling. We sought to further probe Brk regulation as part of signaling pathways relevant to both normal and neoplastic cells. As Brk is abundantly expressed in skin, we examined Brk regulation in response to hepatocyte growth factor (HGF), and macrophage stimulating protein (MSP), peptide ligands specific for Met and Ron receptors, mediators of wound healing in skin cells and cancer cell migration during metastasis. Herein we show HGF and MSP activate Brk kinase activity in Brk+ keratinocytes (HaCaT cells) and breast cancer cell lines (MDA-MB-231 and T47D cells). HaCaT keratinocytes and several Brk-positive human breast cancer cell lines co-express high levels of Met and Brk mRNA and protein; HGF stimulates cell migration in these models. In vitro Brk kinase assays revealed that HGF treatment rapidly activated Brk in HaCaT, MDA-MB-231 and T47D cells, as demonstrated by increased levels of Brk autophosphorylation and phosphorylation of a recombinant Brk substrate, Sam68. Brk gene silencing studies revealed that HGF, but not MSP, induced robust Brk-dependent cell migration. Brk, ERK5, and Sam68 associated in HGF-induced protein complexes in both cell types; these complexes formed independently of Brk kinase activity in COS cells and independently of ERK5 kinase activity in MDA-MB-231 cells. However, ERK5 kinase activity was required for HGF-induced cell migration in MDA-MB-231 cells. ERK5 was required for breast cancer cell, but not keratinocyte cell migration, which became ERK1/2-dependent upon ERK5 knock-down. Notably, the protein tyrosine kinase activity of Brk was not required for HGF-induced cell migration, as indicated by rescue experiments. Further, expression of either wt or kinase-inactive Brk in Brk-null MDA-MB-435 cells activated ERK5 and conferred increased HGF-induced cell migration. Sam68 gene silencing (siRNA) experiments demonstrated that both Brk and its nuclear substrate, Sam68 are required for HGF-induced skin and breast cancer cell migration. We also identified the requirement for Sam68 phosphorylation on threonine/serine residues using a phospho-mutant Sam68 in response to HGF for increased breast cancer cell migration. Phosphorylation of Sam68 on threonine/serine residues mediates splicing of specific mRNAs. We conclude that Brk-dependent signaling to ERK5 and Sam68 mediates cell migration in response to HGF stimulation of Met receptor signaling. Met receptors are emerging as important therapeutic targets for advanced breast cancer. Targeting downstream ERK5 kinase activity or inhibiting the formation of Brk/ERK5/Sam68 complexes may provide an additional means of blocking cell migration associated with breast cancer progression towards metastasis.
Risk Factors for Breast Cancer among American Indian Women
(2016-12) Nadeau, Melanie
Objective: This study was designed to identify risk factors associated with breast cancer among American Indian women, as the first step for developing a risk prediction model similar to the Gail model established for non-Hispanic white women. Methods: A case-control study design was undertaken. Cases and controls were selected from among women undergoing mammograms at the Quentin N. Burdick Medical Care Facility (Indian Health Service) in Belcourt ND. For each woman with breast cancer (n=141), two controls were selected when possible (n=278). All women completed a breast cancer risk questionnaire at the time of their mammogram. This questionnaire was the primary source of data, supplemented by electronic and medical chart files. The risk factors examined were those included in the Gail model, including woman’s age, age at first live birth, age of menarche, the number of previous benign breast biopsies, and the total number of first-degree relatives with breast cancer. In addition, body mass index and parity were also collected. Odds ratios and 95% confidence intervals were calculated using logistic regression. Results: I did not find an association for American Indian women in North Dakota between most of the risk factors commonly identified in other populations and breast cancer. The majority of the associations were weakly positive with confidence intervals including the null value. Of all the risk factors examined, nulliparity was the only one that consistently showed a positive significant association. Conclusion: Disparities in breast cancer incidence, mortality and screening among Northern Plains American Indians emphasize the need to better understand the risk factors associated with breast cancer in this population. It is my hope that this study will contribute to the development of a National Cancer Institute Breast Cancer Risk Assessment Tool that reflects the risk of breast cancer among American Indian women. Based on the results of my study, the value of risk prediction models in American Indian communities is uncertain and clinicians should be cautious in using the current Gail Breast Cancer Risk Assessment Tool to inform their American Indian patients of their risk for breast cancer.
Self-‐Breast Examinations Are Not Recommended
(2012-07-23) Davison, Scott
Targeting The Janus Kinase Pathway In Tumor Associated Macrophages In Breast Cancer
(2023-07) Bapat, Aditi
Interactions between tumor cells and the tumor microenvironment are critical for tumor growth, progression, and response to therapy. Effective targeting of oncogenic signaling pathways in tumors requires an understanding of how these therapies impact both tumor cells and cells within the tumor microenvironment. One such pathway is the Janus kinase (JAK)/signal transducer and activator or transcription (STAT) pathway, which is activated in both breast cancer cells and in tumor associated macrophages. Inhibitors for the JAK/STAT pathway are currently being investigated to ‘turn off’ the oncogenic signaling in the tumor cells. The studies performed in this dissertation aim to investigate the role of the JAK/STAT pathway in cells of the tumor microenvironment, specifically the tumor-associated macrophages. We have demonstrated that exposure of macrophages to JAK inhibitors leads to activation of NF-κB signaling, which results in increased expression of genes known to be associated with therapeutic resistance. Furthermore, inhibition of the NF-κB pathway improves the ability of ruxolitinib to reduce mammary tumor growth in vivo. We have further investigated the role of STAT5 in macrophages, and its contributions to mammary tumor progression and metastasis. We demonstrate that macrophages regulate the immune environment within the tumor in a STAT5 dependent manner and control metastasis of the primary tumor to distant sites. Thus, the impact of the tumor microenvironment is an important consideration in studying breast cancer and understanding such mechanisms of resistance is critical to development of effective targeted therapies.
There’s a Lump in My Breast…Now What?
(2009-05-01) Martin, Angela Beale
When a patient finds a breast lump either accidentally or by breast self exam, there are many different imaging modalities and/or invasive procedures that may be done to determine if breast disease is present. This pamphlet describes many of the possible options a patient and physician may face to “work-up” a breast lump.

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