Research in the Mark Liu Lab explores several areas of pulmonary and respiratory medicine. Our studies primarily deal with allergic inflammation, chronic obstructive pulmonary disease (COPD) and asthma, specifically immunologic responses to asthma. We have worked to develop a microfluidic device with integrated ratiometric oxygen sensors to enable long-term control and monitoring of both chronic and cyclical hypoxia. In addition, we conduct research on topics such as the use of magnetic resonance angiography in evaluating intracranial vascular lesions and tumors as well as treatment of osteoporosis by deep sea water through bone regeneration.

The bony skeleton is one of the most common sites of metastatic spread of cancer and a significant source of morbidity in cancer patients, causing pain and pathological fracture, impaired ambulatory ability and poorer quality of life.

In our continuous investigation of the mechanism of metastasis in spine tumors and of developing animal models and treatments, our team seeks to understand how cancer cells metastasize to the bony spine.

Our laboratory develops novel techniques to evaluate our animal models of metastatic spine disease.

Our lab currently focuses on three areas of immunotherapy research: gaining a deeper knowledge of the biological underpinnings of human autoimmune response; discovering biomarkers that will help us identify which patients and tumor types are most likely to respond to various immune therapies; and developing immune-based treatment combinations that could deliver a more powerful anti-tumor response than monotherapies.

The Johns Hopkins comprehensive Subependymoma and Ependymoma Research Center divideS its efforts into three areas: basic science, translational research and clinical practice. Each division works separately but shares findings and resources openly with each other and our collaborators. The goal of our united efforts is to optimize current treatments to affect the care received by patients with subependymomas and ependymomas. Also, our clinical, translational and basic science teams work to develop novel therapies to improve and extend the lives of those with these rare tumors.

Effective immune responses are critical for control of a variety of infectious disease including bacterial, viral and protozoan infections as well as in protection from development of tumors. Central to the development of an effective immune response is the T lymphocyte which, as part of the adaptive immune system, is central in achieving sterilization and long lasting immunity. While the normal immune responses is tightly regulated there are also notable defects leading to pathologic diseases. Inactivity of tumor antigen-specific T cells, either by suppression or passive ignorance allows tumors to grow and eventually actively suppress the immune response. Conversely, hyperactivation of antigen-specific T cells to self antigens is the underlying basis for many autoimmune diseases including: multiple sclerosis; arthritis; and diabetes. Secondary to their central role in a wide variety of physiologic and pathophysiologic responses my lab takes a broad-based approach to studying T cell responses.

The main research goals of my laboratory are: (1) to identify and study the biology of novel cancer selective targets whose enzymatic function can be exploited for therapeutic and diagnostic purposes; (2) to develop methods to target novel agents for activiation by these cancer selective targets while avoiding or minimizing systemic toxicity; (3) to develop novel agents for imaging cancer sites at earliest stages. To accomplish these objectives the lab has originally focused on the development of prodrugs or protoxins that are inactive when given systemically via the blood and only become activated by tumor or tissue specific proteases present within sites of tumor. Using this approach, we are developing therapies targeted for activation by the serine proteases prostate-specific antigen (PSA), human glandular kallikrein 2 (hK2) and fibroblast activation protein (FAP) as well as the membrane carboxypeptidase prostate-specific membrane antigen (PSMA). One such approach developed in the lab consists of a potent bacterial protoxin that we have reengineered to be selectively activated by PSA within the Prostate. This PSA-activated toxin is currently being tested clinically as treatment for men with recurrent prostate cancer following radiation therapy. In a related approach, a novel peptide-cytotoxin prodrug candidate that is activated by PSMA has been identified and is this prodrug candidate is now entering early phase clinical development. In addition, we have also identified a series of potent inhibitors of PSA that are now under study as drug targeting and imaging agents to be used in the treatment and detection of prostate cancer.

The Systems Biology Lab applies methods of multiscale modeling to problems of cancer and cardiovascular disease, and examines the systems biology of angiogenesis, breast cancer and peripheral artery disease (PAD). Using coordinated computational and experimental approaches, the lab studies the mechanisms of breast cancer tumor growth and metastasis to find ways to inhibit those processes. We use bioinformatics to discover novel agents that affect angiogenesis and perform in vitro and in vivo experiments to test these predictions. In addition we study protein networks that determine processes of angiogenesis, arteriogenesis and inflammation in PAD. The lab also investigates drug repurposing for potential applications as stimulators of therapeutic angiogenesis, examines signal transduction pathways and builds 3D models of angiogenesis. The lab has discovered over a hundred novel anti-angiogenic peptides, and has undertaken in vitro and in vivo studies testing their activity under different conditions. We have investigated structure-activity relationship (SAR) doing point mutations and amino acid substitutions and constructed biomimetic peptides derived from their endogenous progenitors. They have demonstrated the efficacy of selected peptides in mouse models of breast, lung and brain cancers, and in age-related macular degeneration.

Our lab is focused on using comprehensive gene expression, methylation and sequencing and metabolomics analysis to identify alterations in breast cancer, and exploiting these for early detection and therapy. Among deferentially expressed genes, our lab has focused on the HOX genes. HOX genes are intimately involved in the development of resistance to both chemotherapy and to agents targeting the estrogen receptor. Our work explores the alternate pathways that are activated by HOX proteins leading to this resistance and novel treatments to overcome resistance in both tissue culture and xenograft models. In addition, epigenetically silenced genes and a metabolic reprogramming in tumors also trigger novel early detection and therapeutic strategies. We are testing the utility of differentiation therapy through reactivating RAR-beta in breast cancer using histone deacetylase inhibitors with great success. Also, we are targeting enzymes involved in gluconeogenesis and glycolysis with small molecule FDA-approved antimetabolites to achieve antitumor effects.

Our scientists pursue out-of-the-box approaches at the very edge of knowledge to: 1) Elucidate the molecular/cellular/physiological landscapes of ovarian and uterine cancers. 2) Understand the earliest events in their development and mechanisms of tumor evolution/dormancy and drug resistance. 3) Deliver promises for better prevention, detection and treatment to women who have diseases or are at an increased risk to have these cancers.