Siyuan Zhang - US grants

Project Summary/Abstract Title: Dissecting the Role of Src Family Kinases in Breast Cancer Brain Metastasis PI: Siyuan Zhang, M.D., Ph.D., The University of Texas M.D. Anderson Cancer Center I received my M.D. in 1998 from Peking University Health Science Center and a Ph.D. degree in Cancer Biology from the National University of Singapore in 2005. My Ph.D. training was focused on deciphering the molecular mechanisms of the anti-cancer activity of parthenolide - an active component in natural product feverfew. I was the first author in 7 of the 9 papers I published during Ph.D. training. I joined Dr. Dihua Yu's group at The University of Texas M.D. Anderson Cancer (MDACC) in 2007 to pursue my goal of making discoveries of clinical impact. My research elucidated a key mechanism of trastuzumab resistance and led to the development of a novel clinically-translatable combinatorial regimen for trastuzumab-resistant patients. Meanwhile, I am also investigating the role of PTEN loss in breast cancer brain metastasis. My current research goal is to study the role of certain genetic alterations in breast cancer brain metastasis and establish myself as an independent researcher through K99 funding. My long-term research goal will be focused on two important areas: (1) Basic research, investigate the mechanisms of metastasis by focusing on the contribution of the pre-metastatic microenvironment; and (2) Translational research, based on basic research findings to identify, design and pre-clinically test novel therapeutic regimens for treatment of cancer metastasis. To achieve my short-term and long-term career goals, during the K99 mentored phase of this grant, I will receive comprehensive training based in an unmatched training environment for cancer research- MDACC. I will cooperate with my mentors and actively participate in formal courses, workshops and seminars to broaden my knowledge and skills, particularly in genetically-engineered mouse models. The career development training in scientific writing, research ethics, lab management and leadership skills will further facilitate my transition as an independent scientist. My research plan is focused on the role of Src family kinases (SFK) in breast cancer brain metastasis. Among 1.3 million women diagnosed with breast cancer every year worldwide, about 10- 16% will develop brain metastases. Even with most advanced clinical care, the overall survival for brain metastasis patients is less than 14 months from diagnosis. At present, no effective treatment exists for patients with refractory metastatic breast cancer brain metastasis. Therefore, novel and effective therapeutic approaches are urgently needed for this population. Unfortunately, developing effective therapeutics for brain metastasis is largely hampered by a shortage of in-depth understanding of the basic mechanisms of brain metastasis. Our preliminary studies suggest that Src family kinase c-Src plays an important role in both metastatic tumor cells and brain metastasis microenvironments. The major goal of the proposed project is to use innovative approaches to dissect the role of Src family kinases in the brain metastasis process and develop novel therapies for breast cancer brain metastasis patients. We propose three comprehensive aims: 1) Aim 1 (K99 phase): Determine the role of tumor SFK activation in breast cancer brain metastasis. 2) Aim 2 (R00 Phase): Determine the impact of SFK activation in the brain pre-metastatic microenvironment on breast cancer brain metastasis. 3) Aim 3 (R00 Phase): Investigate the pre-clinical efficacy of novel SFK-targeting therapeutic regimens in the treatment of breast cancer brain metastasis. Success of the project will promote my career transition from my position as a mentored postdoctoral fellow to becoming an independent scientist with my own research direction. More importantly, novel insights from this study into the mechanisms of breast cancer brain metastasis will guide the development of novel clinically-translatable regimens that offer fresh opportunities for the treatment of a devastatingly intractable disease.

? DESCRIPTION (provided by applicant): Every single cancer survivor fears relapse. While being free of the primary tumor after treatment is encouraging, it is emotionally devastating to step out of the clinic after a yearly checkup with a diagnosis of metastatic disease. Approximately 90% of cancer lethality is due to metastasis - the spreading of primary tumor cells to distant organs. Despite a dramatic increase in early screening methods and comprehensive treatment regimens for primary breast tumors, the overall mortality of patients who relapsed with metastatic cancer in the US has not changed in the past two decades. Clinical failure in treating metastatic tumors is largely due to the evolutionary nature of tumor metastasis. In order to survive and establish secondary tumors in a different tissue microenvironment at distant organs, disseminated tumor cells have to adapt (metastatic evolution) to the host environment. Clinically, metastatic tumors exhibit drastically different characteristics from their primary counterpart. Therefore, current cancer treatments, designed based on the features of primary tumors, are rarely effective. Optimal design of breakthrough anti-metastasis therapies relies on our in-depth understanding of the common and functionally important traits during the early metastatic evolution. In this proposed study, we will use breast cancer brain metastasis as model system and take state-of-the-art approaches to trace and analyze a single cancer cell within its precise metastatic microenvironment from the initial moment of metastatic colonization. This collaborative effort from a multidisciplinary team, including a cancer biologist, a computational biologist, a mathematician and a bioinformatician will allow us to: 1) depict the dynamics of gene transcription during the different stages of brain metastasis at single cell level; 2) visualize th behavior of a single colonized metastatic tumor cell and its interaction with the microenvironment through real-time intravital imaging and deep tissue imaging; 3) mathematically integrate molecular (RNA-seq), behavioral (intravital) and structural (deep tissue imaging) information to identify the common and functionally important early metastatic evolutionary traits during the breast cancer brain metastasis in its native tissue context. Shifting the current clinical treatment model relies on new in-depth mechanistic insight obtained through basic and pre-clinical innovative research. Utilizing cutting-edge sequencing and imaging modality in our proposed study, we will have the capacity to systematically dissect traits of early metastatic behavior and discover potential novel therapeutic targets for paradigm-shifting novel adjuvant therapy tailored to specific target metastatic evolution. The conceptual validation from our bold and pioneering attempt proposed in this study will serves as a blueprint for a new category of adjuvant therapies for effective anti-metastasis treatment.

Project Summary Title: Mechanisms of neuroinflammation in brain metastasis progression Despite significant progress in early cancer screening and treatment regimens for primary tumors, the overall mortality of patients with metastatic relapse has not improved in the past two decades. Many sites of metastatic relapse are commonly diagnosed in the clinic, but brain metastasis is the most devastating with a median survival of fewer than six months. Thriving in a sanctuary protected by the blood-brain barrier (BBB), brain metastases are shielded from most anti-cancer drugs. As a result, the incidence of brain metastasis is increasing, despite increasing control of primary tumors. Thus, to reduce cancer mortality, rationally designed therapeutics, based on a mechanistic understanding of metastasis in the context of the unique brain microenvironment, are urgently needed for brain metastasis patients. The immune system has indisputable and ubiquitous roles in regulating both primary tumors and metastases. Traditionally viewed as immunoprivileged organ, the role of neuroinflammation in brain tumor progression is largely underexplored. In this proposed study, we will use transgenic mouse models and state-of-the-art genomics and imaging approach to trace and analyze the role of highly heterogeneous cell types involved in neuroinflammation and their roles in regulating brain metastatic outgrowth. This collaborative effort from a multidisciplinary team, including a cancer biologist, an expert in neuroinflammation, a computational biologist and a bioinformatician and will allow us to: 1) dissect distinct contribution subpopulation of myeloid cells in regulating brain metastasis at phenotypical level (Aim 1); 2) visualize and quantitatively measure the behavior of brain microenvironmental niche and transcriptome heterogeneity of inflammatory myeloid cell that that nurtures metastasis in brain (Aim 2). 3) Targeting pro-inflammatory myeloid cells as means of brain metastasis prevention. Shifting the current clinical treatment model relies on new in-depth mechanistic insights obtained through basic and pre-clinical innovative research. Utilizing cutting-edge sequencing and imaging modality coupled with classic transgenetic models and clinical tissue samples, we now have the unprecedented capacity to systematically dissect the traits of metastatic behavior and discover potential novel therapeutic targets for paradigm-shifting novel adjuvant therapy for brain metastasis patients.

Project Summary Title: Neural Niche in Promoting Brain Metastatic Tumor Progression Metastatic progression at the brain is a multi-step, evolutionary process that is accomplished through a consistent interplay between disseminated tumor cells and brain microenvironment - the niche. Despite significantly improved control of primary tumors, the incidence of brain metastasis is increasing! To reduce cancer mortality, rationally-designed therapeutics, based on a mechanistic understanding of metastasis in at the unique brain metastatic niche, are urgently needed for brain metastasis patients. What's the brain metastatic niche? In the brain microenvironment - the niche - is a myriad of diverse cell types that have been speculated to contribute to the brain tumor and brain metastasis development, including endothelial cells, astrocytes, neural stem/progenitor cells (NSC hereafter) and increasingly appreciated brain immune cells. Despite studies of astrocytes, how do the NSC and its progenies respond to brain metastatic colonization and regulate brain immune landscape and the metastatic outcome has yet to be systematically investigated. Our preliminary studies have demonstrated that NSC migrates to colonized tumor cells and NSC is functionally essential for brain metastasis progression. Intriguingly, ample evidence from in the field of neuroscience suggests an immune suppressive role of NCS during the brain inflammation. Thus, in this proposal, we hypothesize that NSC and its progenies' brain metastasis tropism and potentially consequential immunosuppressive activity could contribute to an immune-suppressive metastatic niche, facilitating brain metastasis progression. In this proposed study, we will use transgenic mouse models and state-of-the-art genomics and imaging approach to trace and analyze the role of highly heterogeneous cell types involved in NSC differentiation and immune suppression and their roles in regulating brain metastatic outgrowth. This collaborative effort integrating multidisciplinary expertise, including cancer biology, neuroscience, computational biology, allow us to: 1) examine and trace the NSC differentiation response to brain metastasis at the phenotypical level; 2) visualize and quantitatively measure the behavior of brain metastatic niche cells and their transcriptome heterogeneity; 3) examine the mechanism by which neural cells derived from NSC promotes brain metastasis progression. New in-depth mechanistic insights obtained through basic and pre- clinical innovative research will pave the way to future brain metastases treatments.

Project Summary Metastasis is the major cause of cancer mortality, with brain metastasis being the most aggressive and incurable form of metastatic recurrence. The prognosis for breast cancer patients with brain metastasis is devastatingly poor with a median survival of less than six months. Brain metastasis relapse depends on the intricate interplay between disseminated tumor cells and components of the brain metastatic microenvironment - the niche. To combat breast cancer mortality, it is imperative to develop rationally-designed strategies to prevent brain metastasis relapse. The immune system plays a significant role in regulating both primary and metastatic tumors. The gut microbiota - an ecological community of commensal, symbiotic, and pathogenic microorganisms consistently primes and reshapes the immune surveillance system during aging. Mounting evidence in the neuroscience field demonstrated a clear connection between gut microbiota dysbiosis and brain inflammation as well as various neurological diseases. As brain metastasis relapse often occurs in aged breast cancer survivors, in this proposed study, we will focus on delineating mechanisms by which the microbiota-host immune interaction influences metastatic progression in the aged female population. We postulate that age-related gut dysbiosis may reshape the brain immune metastatic niche to influence brain metastatic relapse. Our overarching goal is to dissect the mechanistic connection between gut dysbiosis and brain metastasis relapse and identify clinically actionable probiotics modulation strategies tailored to aged breast cancer survivors to prevent brain metastatic relapse. Based on well-established aging models, cutting-edge single-cell genomics, and metagenomics approaches, we will examine molecular changes in brain metastatic tumors with gut microbiota alterations in the aged host. Then design and test targeted microbiota-modulation strategies to prevent brain metastatic relapse in aged hosts. This project is the first attempt to explore the mechanistic link between the gut microbiota and breast cancer brain metastatic niche in the aging context. From the cancer prevention perspective, mechanistic insights via examining age-associated dysbiosis in regulating brain metastasis relapse will guide personalized microbiota-modulation strategy that is tailored to each breast cancer survivor to prevent deadly brain metastatic relapse.