SCIENTIFIC FOCUS AND GOALS
1. Overview of Program Themes The scientific focus of the Cell Growth and Survival (CGS) Program begins where that of the DNA Damage and Cellular Defense Program leaves off. It is widely appreciated that oncogenesis is initiated by mutational changes in DNA that result in loss of normal cellular growth control. However, the ability to cause cancer also involves progressive changes in the cellular signals that mediate cell survival, proliferation and death. This latter area constitutes the scientific focus of the CGS Program. This area includes both the extracellular signals that mediate cell growth versus cell death, as well as the network of intracellular signaling pathways that mediate these critical decisions as to a cell’s fate. The focus on proliferative signaling mechanisms that regulate cell growth leads directly to new strategies for cancer prevention by inhibiting or delaying the progression to cancer. Likewise, the focus on mechanisms of cell death leads directly to new strategies for cancer treatment by developing new approaches for killing cancer cells.
The CGS Program is divided approximately evenly between those investigators primarily investigating regulation of cell growth versus those primarily interested in regulation of cell death. These two areas constitute the major themes of the program. Within each of these, there are key areas of scientific focus that are generating ground-breaking, novel concepts. These areas are also intense areas of collaboration across CCCWFU Programs. A number of novel contributions from the CGS Program to the national cancer effort have emerged since the previous review. These themes directly reflect the value-added as a result of Cancer Center funding: thematic development and recruiting by the Cancer Center leadership; sheparding the development of these themes by the Program Director; a high degree of collaboration within the CGS and with other Programs, major participation in the Centers of Excellence, and effective use of shared facilities.
2. Scientific focus and goals of each theme
Regulation of cell growth
A major focus of collaborative research among those interested in regulation of cell growth is the role of dietary factors on the regulation of cell proliferation. The goal of this research is to understand the mechanisms by which dietary factors can send signals that inhibit cell proliferation. This understanding will form the basis for dietary interventions in the prevention and treatment of cancer.
Goal 1. Understand the mechanism of regulation of cell proliferation by vitamin D and soy isoflavones
The antiproliferative effects of vitamin D and a fascinating synergy with soy isoflavones are particularly active areas of investigation within the CGS Program, and provide a basis for thematic integration with members of the Cancer Control and Clinical Research Programs and within the Prostate Center of Excellence. The antiproliferative effects of dietary soy and their interaction with estrogenic factors are also a major focus of collaborative activity within the Breast Center of Excellence. This research shows strong synergy with the complementary and alternative medicine (CAM) theme within CCCWFU.
Much of the emphasis on vitamin D is in its potential to contribute to control of prostate cancer, due to the presence in normal prostate epithelial cells of one of the key enzymes which converts the vitamin Dprohormone to its active form. This is a robust area of collaboration among CGS members, and has matured into one with a high degree of translational research (see diagram, next page). This area began as a classic example of translational research from the bedside to the bench, in which the epidemiological studies of vitamin D and prostate cancer of Dr. Gary Schwartz’s group stimulated basic research on vitamin D and prostate biology by Dr. Scott Cramer and other members of the CGS Program. This productive collaboration has led to additional translational research projects, from the bench to the bedside, such as the Zemplar trial (a less calcemic analog of vitamin D) in the Clinical Research Program. It has also led to a collaborative project within the CGS Program on vitamin D and radio sensitization, and to a collaboration within the CGS Program on the synergism between vitamin D and soy isoflavones.
Research on the beneficial effects of soy originated in Dr. Mark Cline’s work in primate and rodent models of cancer, which has a translational outgrowth in a project to determine the effects of dietary soy on biomarkers in human prostate cancer. Furthermore, the new discovery of the synergism between vitamin D and soy isoflavones has led to the development of clinical trials to develop novel dietary interventions for the control of prostate cancer, currently planned in collaboration with Dr. Peter Clark and members of the Cancer Control and Clinical Research Programs.
Core facilities have played key roles in the development of this theme. The acquisition of samples of prostatectectomy specimens through the Tumor Tissue Core has been critical for generating primary cultures of normal prostatic epithelial cells and prostate cancer cells for studies on the role of vitamin D and soy isoflavones on cell proliferation. The Biostatistics Core plays a major role in the collaboration of CGS members with Cancer Control and Clinical Research Programs in the translational research projects.
Goal 2. Elucidate the role of dietary lipids in regulating cancer cell proliferation and metastasis.
For more than 2 decades, epidemiologic studies have reported associations between dietary fat and the risk of prostate cancer. These epidemiologic findings have been translated into basic research projects to determine the role of dietary lipids in regulating cancer cell proliferation and metastasis. These are major themes in collaborative projects within the Prostate and Breast Centers of Excellence. Building on traditional strengths of WFUSM in lipid signaling, as well as the interests of recently recruited faculty, a particularly strong interdisciplinary team has been developed within the CGS program to pursue this important connection between dietary lipids and cancer of the prostate and breast. This team consists of Drs. Yong Chen, Isabel Berquin, Joseph O’Flaherty, Larry Daniel, Iris Edwards and Robert Wykle. The research is focused on how n-3polyunsaturated fatty acids (PUFAs) inhibit (whereas n-6 PUFAs stimulate) prostate cancer cell growth. There is also an important connection of PUFAs with bioactive lipids such as platelet activating factor (PAF) in breast and prostate cancer that is another major focus of investigation.
The development of this theme depended heavily on recruiting new faculty into the CGS program during the present funding period. The recruitment of Drs. Chen and Berquin to WFUSM was one of the keys to development of this theme. Another key was the recruitment to the CGS Program of Drs. Edwards, O’Flaherty, and Wykle, who were already on the faculty of WFUSM. The research of these investigators was previously focused on heart disease and inflammation, but has become cancer-focused as a result of thematic development within the CGS Program under Dr. Lyles’ leadership.
The Biomolecular Resource Facility has played a large role in the development of this theme by providing sophisticated mass spectrometry analysis of lipids and other metabolites. This is a major strength that distinguishes the research in lipids and cancer at WFUSM.
Goal 3. Understand the role of reactive oxygen species in regulating cell proliferation
It is widely appreciated that cells produce reactive oxygen species (ROS) as by-products of metabolism, and as a result of inflammatory processes, and that these ROS can have cell damaging and mutagenic effects that promote oncogenesis. The origins and expertise of research on ROS is primarily attributable to investigators in the DNA Damage and Cellular Defense (DDCD) Program. This has been a major area of translational research in the CCCWFU, with basic research on ROS damage conducted in the DDCD Program, and clinical research such as the lycopene trial done in the Clinical Research Program. However, the phenomenal success of Dr. Leslie Poole’s work spans both the DDCD and the CGS Programs in a key interdisciplinary effort.
A major change in our thinking about ROS has come about with the realization that ROS production by most cells serves as a signaling mechanism. This revolution has come about through the discovery (by Dr. Poole and others) of reversible mechanisms of protein modification by ROS involving the formation of cysteine sulfenic acids, and other modifications, that alter the activity of key proliferative signaling molecules, such asphosphatases and transcription factors. The focus of research on ROS proliferative signaling is on discovering the key molecules that are affected and the mechanisms of generation and inactivation of ROS during proliferative signaling. This is a particularly “hot” area of research involving collaboration between members of the CGS program (Drs. Daniel and Grayson) and the DDCD program (Dr. Poole). This focus on redox biology includes a substantial computational biology component (Dr. Jacqueline Fetrow, in Mathematics and Computer Science at WFU, DDCD Program member), and a major systems-biology effort in modeling redox signaling pathways conducted in collaboration with the Virginia Bioinformatics Institute at Virginia Tech.
The Biomolecular Resource Facility plays a key role in making this work possible. Mass spectrometry analysis of proteins (proteomics) is important for analyzing protein modifications to identify cysteine sulfenic acids. This facility is also important for establishing the identity of unknown proteins containing modified cysteine sulfenic acid using proteomics technology.
Regulation of cell death
The regulation of programmed cell death or apoptosis is a critical theme in cancer biology, involving both the suppression of apoptotic signaling during oncogenesis and the induction of apoptosis during cancer therapy. The CGS program has had a strong emphasis on apoptotic signaling centering around the efforts of Dr. Costas Koumenis, who has focused on signaling in hypoxia and radiotherapy, and Dr. Mark Willingham, a widely recognized expert on apoptosis. Targeted recruiting in the area of cell death (first Dr. Thorburn, and more recently Drs. George Kulik and Jason Grayson) has substantially strengthened thematic development in this area.
The Microscopy Core Laboratory directed by Dr. Willingham is a key facility that serves as a focus of collaboration on the induction of apoptosis. The availability of time-lapse, fluorescence, confocal, and electron microscopy facilities is critically important for determining the morphological changes that accompany apoptosis, and for cellular localization of important molecular targets.
Goal 4. Determine how translational control and endoplasmic reticulum-based stress responses in hypoxia lead to alterations in apoptotic signaling
Solid tumors are seldom homogeneous, but instead have different microenvironments that can profoundly influence therapeutic approaches. Perhaps the best studied component of the tumor microenvironment is the presence of low oxygen tension, or hypoxia. Hypoxic areas within the tumor mass provide significant difficulties for standard anticancer therapy, as these areas present a physical barrier to chemotherapeutic agents, and are more resistant to radiation therapy because of the lack of ionizable oxygen. As a result, tumor hypoxia correlates with an overall poor patient prognosis. The transcriptional control of hypoxia-inducible genes has been an area of focus by cancer biologists for many years. The work of Dr. Costas Koumenis has shown that control of gene expression in hypoxic tumor cells also occurs at the level of translation. Further, this translational control reflects the activation of an endoplasmic reticulum stress response that serves to protect cells from the harmful effects of hypoxia. This is also a “hot” area of research that has led to a series of active collaborations, both with members of the CGS program, such as Drs. Lyles and Steven Kridel, as well as with others outside of WFUSM.
Goal 5. Determine the mechanisms of genetic control of innate antitumor immune mechanisms
Among the group focused on regulation of cell death, a major common theme is the relationship between signaling in cancer and inflammation. It has been appreciated for many years that immune/inflammatory mechanisms constitute a promising avenue for inducing cell death in tumors. Recent collaborative research in the CGS program has yielded striking new potential to identify innate and adaptive immune mechanisms that may be involved in genetic resistance to cancer as well as avenues for tumor therapy. As shown in the diagram at left, this multidisciplinary effort involves a group of investigators in the CGS Program working on mechanisms of innate and adaptive immunity, including Toll-like receptors (TLRs), dendritic cells, and T lymphocytes (Drs. Liwu Li, Martha Alexander-Miller, and Grayson). New recruits to the CGS program include Drs. Li and Grayson. Together with Dr. Alexander-Miller, their research provides the background and expertise for collaborations with geneticists, cancer biologists, virologists, and biochemists to exploit the relationship between immune/inflammatory mechanisms and the control of cancer.
The genetic control of innate immunity in prostate cancer has emerged as a new thrust of translational research in the Cancer Center through the collaboration of Dr. Li with Dr. Jianfeng Xu’s group in the WFU Center for Human Genomics Center (Cancer Control Program). The initial finding of polymorphisms in genes for TLRs that are genetically linked to the occurrence of prostate cancer has stimulated a major effort to define other genes in inflammatory pathways that are involved in resistance/susceptibility to prostate cancer in humans.
Another striking example of the genetic control of innate antitumor mechanisms was the discovery at Wake Forest of mutant mice with a previously unrecognized, genetically determined cancer resistance trait that is mediated through cytolytic death of cancer cells (Drs. Zheng Cui and Willingham). Tumor cell death occurs through an innate immune response that is T cell independent. The focus of this research is on identifying the genetic basis for cancer resistance, as well as the immune mechanisms involved. This research involves major collaborations among members of the CGS program, such as Dr. Alexander-Miller, and investigators in the Cancer Control Program who are part of the WFU Center for Human Genomics.
Goal 6. Understand the antagonism between innate inflammatory and antiviral signals and cell proliferation, and develop novel oncolytic viruses
Recent research on intracellular signaling by members of the CGS Program has suggested that the antagonistic relationship between cancer and inflammation extends well-beyond concepts such as “immune surveillance”. For example, it is now known that there is a generally antagonistic relationship between proliferative signaling pathways and antiviral pathways. As a result, many cancer cells down-regulate their antiviral pathways during tumor development. This makes them correspondingly more susceptible to virus infection and killing. This novel idea has led to the rapid growth of the field of “oncolytic viruses,” which constitutes a major focus of collaborative research between virologists (Drs. Lyles, Griffith Parks, and David Ornelles), cancer biologists (Drs. Cramer, Chen, Koumenis, and Kulik), and immunologists (Drs. Alexander-Miller and Grayson) in the CGS Program. The development of novel replication-competent oncolytic viruses for the treatment of prostate cancer is a major focus of collaborations with members of the Clinical Research program in the Prostate Cancer Center of Excellence. An emerging area of focus is also the development of novel oncolytic viruses for the treatment of breast cancer, which involves collaboration in the Breast Center of Excellence, and glial tumors, which involves collaboration within the Brain Tumor Center of Excellence (Dr. Waldemar Debinski).
In addition to the Microscopy Core Laboratory described above, this group consists of heavy users of the Cell Culture and Viral Vector Core Laboratory. This facility provides critical support for the production and characterization of recombinant viral vectors for the research of this group. The Biomolecular Resource Facility is important for DNA sequencing of mutant viral genomes, and the Micro array Core Laboratory has emerged as a powerful element in the analysis of tumor antiviral responses and the induction of apoptosis. The assistance of the Biostatistics Core has been very important for analyzing data from treatment of tumors in mice with oncolytic viruses.