Angiogenesis and Growth Control
Research Project Awards
- Investigation of Improved Drug Delivery in Breast Cancer – Orhan Nalcioglu, Ph.D., University of California, Irvine
- MRI Detection of Microvascular Status in Breast Cancer – Robert C. Brasch, M.D., University of California, San Francisco
- Prevention of Breast Cancer by Blocking Integrin Function – Jeffrey W. Smith, Ph.D., La Jolla Cancer Research Foundation
Investigation of Improved Drug Delivery in Breast Cancer
Orhan Nalcioglu, Ph.D.
University of California, Irvine
Improved delivery of diagnostic and therapeutic drugs to breast tumors is important for early detection and prevention of the progression of breast cancer. In this investigation, we will employ various vaso-active drugs to increase the preferential delivery of drugs to the tumors. If these drugs are used in conjunction with agents that are employed for imaging purposes they would increase the accuracy of the early detection of breast cancer. On the other hand, if they are used in combination with certain types of drugs for treatment they would deliver a larger proportion of their effect to the tumor while not damaging the surrounding normal tissues. The assessment of the accuracy of the new technique will be measured by dynamic magnetic resonance imaging (dMRI). The proposed investigation will specifically deal with the following BCRP priority areas: 1) pathogenesis of breast cancer (breast cancer biology), 2) prevention of disease progression by predicting the outcome of treatment, and finally 3) improvement of early detection of breast cancer by exploiting vascular properties of such tumors. In order to achieve the above goals, we will exploit the fact that tumor microvasculature is hyperpermeable (hyper-leaky) to large molecular weight imaging and therapeutic drugs as compared with normal blood vessels. We will also use our previous finding that MRI techniques combined with pharmacokinetic modeling can be used to measure the permeability in tumors as a function of spatial location. We will test the effect of drugs that alter the permeability of tumor vessels temporarily so that large molecular weight agents can be trapped in the extravascular space and spend a longer time in the tumor. The proposed studies will employ animal tumor models to understand the performance of the proposed approach in controllable tumor models so that the application of the technique can be extended to human breast cancer. Characterizing tumor permeability and other tumor transport parameters in breast cancer is important for the understanding of the pathogenesis of the disease, improved detection during the early stages due to the angiogenesis of neovasculature and corresponding vascular leakage, and in addition may aid in the prediction of bioavailability of chemotherapeutic agents to prevent the progression of disease. The successful outcome of the proposed research will positively impact all of the areas mentioned above.
MRI Detection of Microvascular Status in Breast Cancer
Robert C. Brasch, M.D.
University of California, San Francisco
Favored possibilities to reduce breast cancer mortality and associated suffering include 1) the accurate detection of cancer at an earlier stage when the arrest of tumor growth and/or metastasis is more often successful, 2) a more effective utilization of available therapies to prevent progression, and 3) the institution of new and improved prevention strategies. The proposed research in this application and its clinical implementation have the potential to advance all three approaches. Program goals are to investigate the potential of a new class of diagnostic drugs, macromolecular contrast media, and new magnetic resonance imaging (MRI) techniques for improved detection and staging of breast carcinoma. The proposed MRI technique should provide high sensitivity and improved specificity for breast cancer detection over currently available detection methods. MRI, a technique which is decreasing in price and is becoming more widely available to the California patient population, offers several advantages over conventional radiographic mammography including absence of ionizing radiation, images in multiple planes, and superb soft tissue contrast; MRI is particularly beneficial for the 25% of women with radiographically dense breasts.
Small vessels within cancers are known to have unique anatomic and functional features; the new MRI techniques under development provide a non-invasive method to detect these pathological microvascular characteristics. This project is relevant to the BCRP priority issues in several ways. Knowledge about breast cancer micro vessels can be clinically useful 1) to permit earlier detection and more accurate differentiation of cancers from other mass lesions, 2) to determine the aggressiveness and metastatic potential of an individual cancer and thus to more accurately predict the clinical course, and 3) to choose the most appropriate drugs to prevent progression based on micro vessel permeability. A further benefit of this research should be the better understanding of breast cancer biology and specifically of tumor angiogenesis (growth of new vessel into tumors), a process critical to uncontrolled growth and metastasis of cancer. Dynamic MRI contrast enhancement patterns in four mammary cancers, presenting a spectrum of aggressiveness, microvascular densities, and endothelial permeabilities, will be compared to each other and to normal tissues. MRI techniques will be correlated with measured invasiveness including pathology, accumulation of antineoplastic drugs, and tracer kinetics. To improve the quantitative aspects and clinical practicality of the MRI microvascular characterizations, new and faster MRI acquisition and data analysis techniques will be tested and compared. The project is multidisciplinary, requiring contributions in physics, chemistry, pharmacology, radiology, pathology and oncology.
Prevention of Breast Cancer by Blocking Integrin Function
Jeffrey W. Smith, Ph.D.
La Jolla Cancer Research Foundation
The primary danger in breast cancer is the spread of the tumor to other organs in the body. Tumor cells use adhesion molecules to migrate, or in essence to "crawl," to other regions of the body. If the activity of such adhesion molecules could be inhibited, then the metastasis of breast cancer could be considerably slowed and perhaps eliminated. Thus, the identification and targeting of adhesion molecules involved in breast cancer should be a high priority.
The central hypothesis of this grant is that adhesion molecules called integrins are key mediators of the metastasis of breast cancer. Integrins were so named because they provide an "integral" link between the inside and outside of the cell. Integrins are produced in all normal cells, but when produced at improper times or locations, like in breast cancer, integrins change cell behavior. We hypothesize that 1) in breast cancer integrins are required for the physical migration of tumor cells to distant organs, 2) that integrins are involved in the changes in gene function within the tumor cells as the tumor cell encounters new environments during metastasis and 3) that inhibitors of integrins can be applied to stop the metastasis of breast cancer.
As the first step in the project, the integrin adhesion molecules that are involved in the migration of breast cancer cells will be identified. Data in the literature correlate the production of integrins possessing the av subunit with invasive breast cancer. This information is an excellent start, but provides only a corelation. We aim to determine if there is a causal relationship between the presence of av-integrins and invasive breast cancer. In the initial phase of the project the ability of each of the four known av-integrins to enable tumor cell migration and tumor metastasis will be measured. Results from these experiments will be the first measure of the ability of these adhesive molecules to increase tumor cell motility and metastasis. The integrins that are found to cause tumor invasion will be designated as targets for inhibition of metastasis.
The progression of breast cancer is known to be the result of a series of genetic changes. In the second phase of the project we will examine the possibility that integrin adhesion molecules actually signal the cell to begin these genetic changes. Such a hypothesis is suggested because the integrins mediate the physical contact between the cell and its environment. As the tumor cell migrates to different locations, the integrin contacts different matrices. We hypothesis that integrins "sense" the environment of the tumor cell and signal corresponding genetic changes that could actually "feed the fire," initiating further aberrant genetic alterations in the tumor cell.
The final phase of the study will be a test to determine whether two powerful inhibitors of av-integrins can block the metastasis of mammary carcinoma in vivo. One inhibitor is a small organic molecule that binds the adhesive site on the av-integrins. The other inhibitor is a human antibody that we have engineered to inhibit the adhesive activity of integrins. Results from these experiments will indicate the potential for blocking breast cancer metastasis by interfering with integrin function.
Innovative Developmental and Exploratory Awards (IDEAs)
Platelet Factor 4: A Marker for Malignant Breast Tumors
Per Borgström, Ph.D.
La Jolla Institute for Experimental Medicine
Angiogenesis, a fundamental process by which new blood vessels are formed, is rare in adults under normal physiological conditions. However, in pathophysiological conditions like cancer, unrestrained angiogenesis occurs. Rapid tumor growth is dependent on angiogenesis to support the metabolic need of the fast-growing transformed tumor cells and the growth of the tumor beyond a certain size requires angiogenesis. In breast cancer there is a significant association between the density of vessels in the tumor (a consequence of the angiogenic process) and overall survival as well as relapse-free survival in both node-negative and node-positive patients. Since the density of vessels in a tumor is an independent prognostic indicator in breast cancer, specific markers suitable for imaging of angiogenesis could contribute to the early detection of malignant breast tumors. We have previously shown that platelet factor 4 (PF4) selectively binds to newly formed vessels, i.e., sites of angiogenesis, and the overall goal of this project is to investigate the potential of PF4 as an imaging marker for breast cancer angiogenesis.
Our first goal is to characterize a suitable human breast cancer cell line using our newly developed in vivo video-microscopy technique. Our technique allows detailed repeated in vivo real time observations of tumor microvasculature, and permits quantitative evaluation of tumor growth and tumor angiogenesis in vivo. Currently there is no reliable information on in vivo angiogenic behavior of breast cancer, and the results from this investigation will inevitably provide new and important results which are a prerequisite for the evaluation of PF4 as an angiogenesis marker.
Our second goal is to investigate binding characteristics of systemically injected fluorescently labeled PF4 (FITC-PF4) to the microvasculature of human breast tumors. In the present investigation, we are using video-microscopy and fluorescently labeled PF4 which will allow us to characterize in detail the binding characteristics of intravascular PF4 which is a prerequisite for future use of other PF4 conjugates in clinical screening techniques. To the extent that we find that FITC-PF4 selectively labels the vessels of human breast cancer cell lines, such results would lend strong support for the use of PF4 as an in vivo marker for breast cancer angiogenesis. The proposed studies provide a systematic approach to evaluate the potential of PF4 as an imaging marker for breast cancer angiogenesis and thus could be an important step towards the development of novel screening techniques to improve the early detection of malignant breast tumors.
New Investigator Awards
Growth Inhibition of Breast Cancer Cells by Interferons
Ke Shuai, Ph.D.
University of California, Los Angeles
Interferons (IFNs) have antiproliferative actions and can inhibit the growth of many tumor cells including breast cancer cells. Unfortunately, clinical trials using IFN as a single drug for breast cancer have not been satisfactory due to a wide range of side effects resulting from the usage of high doses of IFNs. However, it has been shown that the strategy to use tamoxifen in combination with IFN can greatly enhance the effects of tamoxifen on breast cancer. Based on our most current understanding of the molecular basis of IFN action, we have recently discovered a protein molecule which can greatly enhance the antiproliferative effects of IFNs. The overall goal of this project is to study the effects of this protein molecule on the growth inhibition of breast cancer cells. We will also test our hypothesis that this protein molecule can greatly enhance the antigrowth effects of tamoxifen on breast cancer cells. This research will lead to the design of rational preventative strategies for breast cancer employing IFNs.
To study the effects of this molecule on the growth inhibition of breast cancer cells, we will first introduce this protein into breast cancer cells using a system in which we can control the level of this protein. We will then analyze the growth of breast cancer cells in the presence of different levels of this protein molecule. The optimal concentrations of IFNs for growth inhibition of breast cancer cells in the presence of this protein will also be determined. Next, we will investigate the possibility that this protein molecule can greatly enhance the anti-proliferative effects of tamoxifen on breast cancer cells. The growth inhibition of breast cancer cells by tamoxifen in the presence or absence of this protein molecule will be determined and analyzed. We will also determine the potential effects of this protein molecule on the level of estrogen receptor by Northern blot and Western blot analysis.
Postdoctoral Fellowship Awards
Growth Factor Control of Breast Tumor Cell Proliferation
Richard C. Kurten, Ph.D.
University of California, San Diego
The normal cyclic renewal of breast tissues is accompanied by variations in epithelial cell proliferation that are regulated by steroid hormones and peptide growth factors which are produced elsewhere in the body. I recently discovered two new human genes involved in the action of epidermal growth factor (EGF), a regulator of cell proliferation in breast tissues. I propose to evaluate their potential utility as targets for controlling the growth of breast tumor cells in tissue culture. This research is intended to provide a new foundation on which to design strategies for preventing disease progression and for treating advanced breast cancer in women. The potential impact of the planned research would be to provide another line of defense against breast cancer. Epidermal growth factor (EGF) regulates cell proliferation by binding its receptor, a large protein spanning the thickness of the cell membrane. The receptor protein has several sections, each of which performs a different, but related function. On the outside of the cell is a section that binds to EGF. When that binding occurs, a section on the inside of the cell becomes active as an enzyme to catalyze reactions. This section of the receptor will be studied in this project because it regulates some protein interactions that preceed cell division. The genes I isolated code for two proteins, corkii-1 and corkii-2, that bind the enzymatic section of the molecule and regulate its level of activity. In so doing, corkii-1 and corkii-2 appear capable of controlling the ability of the EGF receptor to transmit information deeper into the cell. Most importantly, by controlling catalytic efficiency, these molecules set the sensitivity of a cell to EGF and determine the rate at which the cell divides; cells that divide too rapidly form tumors.
I plan to measure the levels of corkii-1 and corkii-2 in normal and malignant cultured cells derived from human breast tissue to establish the relationship between their levels and cellular proliferation rates. In a second line of investigation, molecular approaches employing antisense DNA technology and transfer of synthetic genes will be used to change the level of corkii-1 and corkii-2 in cultured breast tumor cells. The effects of these manipulations on proliferation of cultured breast tumor cells will serve as indicators of the potential utility of DNA-based drugs in slowing or eliminating tumor growth.
