Bryan C. Fuchs, Ph.D. - US grants

DESCRIPTION (provided by applicant): Overexpression of epidermal growth factor (EGF) in the liver induces transformation to hepatocellular carcinoma (HCC) in animal models. A single nucleotide polymorphism (A to G transition at position 61) has been identified in the EGF gene. We have demonstrated increased mRNA stability of the G allele both in hepatoma cell lines and primary human hepatocytes which may serve as a mechanism by which individuals with the G/G genotype have increased serum and liver tissue levels. Our analysis of the distribution of allelic frequencies in cirrhosis populations from both Massachusetts and France revealed that the G/G genotype was significantly associated with risk of HCC relative to the A/A genotype. Currently, the source of excess EGF is unknown. The majority of HCCs develop in the setting of cirrhosis. Therefore, the goal of Specific Aim 1 is to investigate the effects of cirrhosis on EGF expression in serum and the various liver cell populations as monitoring of EGF levels could be used to identify cirrhosis patients at high-risk for HCC. HCC is increasing in incidence both in the United States and worldwide. Given the lack of successful treatment options for HCC, chemoprevention in high-risk patients has been proposed as an alternative strategy. Exceedingly little is known about the molecular pathways leading to hepatocellular transformation. Therefore, the goal of Specific Aim 2 is to examine the signaling pathways initiated during EGF-induced transformation as a means to identify potential therapeutic targets. Small molecule EGF receptor (EGFR) tyrosine kinase inhibitors have proven effective as chemopreventive agents in a rat model of HCC. The goal of Specific Aim 3 is to identify resistance mechanisms in the residual tumors in order to design more effective chemoprevention strategies. The broad long-term objective of this proposal is to develop chemopreventive therapies that can be used to lower EGF levels and/or inhibit EGF-induced hepatocellular transformation. The data obtained from these experiments have broad implications as overexpression of the EGFR is a common event in neoplastic transformation, and we hypothesize that targeting of the EGF pathway may be a novel strategy for chemoprevention.

DESCRIPTION (provided by applicant): The goal of this proposal is to develop an effective magnetic resonance (MR) probe for noninvasive, molecular imaging of renal fibrosis. Renal fibrosis is a hallmark of all chronic kidney diseases (CKD). It is estimated that 500 million peopl worldwide are currently suffering from CKD and many of these patients will progress to end- stage renal disease (ESRD), a devastating disorder that requires dialysis or kidney transplantation. The incidence of ESRD has doubled over the last 25 years in the United States, and in fact, treatment of CKD and ESRD accounted for 27% ($60 billion) of Medicare expenses in 2005. Clinical studies have demonstrated a strong correlation between ESRD and the extent of renal fibrosis. Quantification of renal fibrosis should predict long-term outcome of renal function in CKD patients and could also be used to monitor response to new anti- fibrotic therapies. Currently, biopsy is the gold standard for diagnosing renal fibrosis. However, biopsy is not suitable for monitoring disease progression in CKD patients as it is invasive and subject to sampling error. Therefore, there is a major unmet medical need to develop noninvasive strategies to detect and monitor progression of renal fibrosis. This proposal is in response to RFA-DK-13-026, Novel Methods for Detection and Measurement of Organ Fibrosis in Kidney, Bone Marrow, and Urological Diseases. In particular it responds to the specific need for Novel minimally invasive imaging methods for the detection and measurement of organ fibrosis and to detect changes in fibrosis that quantify progression, stabilization, and/or regression over time and to Correlate fibrotic status with organ dysfunction, recovery, and/or regression Renal function progressively declines in response to the excessive accumulation of extracellular matrix proteins. Myofibroblasts secrete collagens, as well as the enzyme lysyl oxidase (LOX) which crosslinks the collagen fibrils. Recently, we have developed a prototype small molecule magnetic resonance (MR) probe, termed Gd-Hyd, with specificity to cross-linked collagen. In preliminary data we have demonstrated that Gd- Hyd can accurately detect renal, liver and pulmonary fibrosis in small animal models. Since LOX-mediated crosslinking of collagen is an aspect of active disease, our hypothesis is that molecular imaging of LOX-mediated collagen crosslinking accurately reflects renal fibrogenesis and thus can be used to detect renal fibrosis and monitor disease progression and response to therapy. The importance of these studies cannot be overstated as CKD is a major worldwide health problem. The accomplishment of our Specific Aims would lead to a new methodology for identifying fibrotic patients at high- risk for disease progression and poor survival and also for monitoring response to anti-fibrotic therapies.

? DESCRIPTION (provided by applicant): Liver fibrosis is the common result of virtually all chronic liver injuries. During fibrosis, the ongoing cycles of injury and repair lead to accumulation of extracellular matrix rich in fibrillar collagen and eventually disruption of the normal tissue architecture and function. If the underlying cause of disease is suppressed or removed early enough, liver fibrosis has the potential to regress to a lesser stage or even reverse to a normal architecture. However, if left unchecked, fibrosis will progress to cirrhosis, an advanced stage of the disease estimated to affect 1-2% of the world's population. The major clinical consequences of cirrhosis are organ failure and development of hepatocellular carcinoma (HCC), and over a million people worldwide die each year from cirrhosis and HCC. Accumulation of collagen is a hallmark of liver fibrosis. For this reason, collagen deposition is assessed histologically by staining in liver biopsies in order to score disease by traditional pathology methods. However, biopsy is an imperfect gold standard as it can lead to complications, suffers from intra/inter-observer variability, and is associated with sampling error The broad, long-term objective of this proposal is to develop in vivo molecular imaging probes that can be used to non-invasively quantify fibrotic burden and active fibrogenesis over the entire liver. We have recently reported that a collagen-targeted magnetic resonance (MR) probe can accurately quantify fibrotic burden and stage liver fibrosis in a standard carbon tetrachloride mouse model. In this project, we will not only expand upon our studies with the collagen- targeted MR probe but also test a new molecular imaging probe that detects lysyl oxidase-mediated collagen crosslinking - a characteristic of active fibrogenesis. The goal of Specific Aim I is to non-invasively stage fibrosis in several animal models using molecular MR imaging as liver fibrosis results from a variety of different etiologies. In addition, progression of underlyig liver fibrosis is the greatest risk factor for liver failure and HCC. The goal of Specific Aim II therefore is to determine whether assessments of fibrotic burden and/or active fibrogenesis at early time points can predict late-stage liver outcomes including HCC. A few antifibrotic drugs are starting to move into clinical trials. Because disease progression is slow, there is an enormous cost risk to development of these drugs, since clinical trials require large patient populations treated for long periods of time to reach a clinically significant endpoint. The goal o Specific Aim III is to determine whether an imaging biomarker that assesses active fibrogenesis could be used to establish an earlier endpoint which would enable a much larger pool of candidate therapies to move into pivotal clinical trials. Our hypothesis is that molecular imaging of collagen and lysyl oxidase-mediated collagen crosslinking will accurately reflect fibrotic burden and active fibrogenesis and thus can be used to monitor disease progression and response to therapy. The data obtained from these experiments will have immediate impact on the millions of people living with chronic liver disease and should have broad implications as collagen deposition is a common event in organ fibrosis.