Research Focus of the Laboratory: The main focus of investigation in our laboratory is on the Tumor Microenvironment (TME) and its contribution to cancer progression and metastasis (Borriello et al., Cancer Lett. 2016). The main objective of the laboratory is to understand fundamental mechanisms of communication between tumor cells and stromal cells in the TME in order to identify targets for therapeutic intervention that can be tested in relevant pre-clinical models. These data are then used to design early phase clinical trials in children with cancer through collaboration with clinical investigators at the USC-Norris Comprehensive Cancer Center and Children’s Hospital Los Angeles (CHLA). A major focus is on Neuroblastoma (NB), the second most common solid tumor in children and a cancer that is highly metastatic. Our research approach combines cell and molecular biology with pre-clinical animal models in mice. Our research program has 3 major directions:
1. Contribution of cancer-associated fibroblasts (CAF) to neuroblastoma progression: Our laboratory has recently identified in neuroblastoma tumors, CAFs that share phenotypic and functional properties of bone marrow mesenchymal stromal cells (MSC). These cells are educated by NB cells toward a pro-tumorigenic function that enhance NB cell proliferation, survival and drug-resistance through the production of several pro-tumorigenic cytokines and chemokines such as IL-6, IL-8, VEGF, SDF1 and MCP1 (Borriello et al., Cancer Res. 2017, in press). Downstream of these cytokines is the activation of STAT3 and ERK1/2 in NB cells. Ongoing work investigates the effect of blocking STAT3 and ERK1/2 in combination with chemotherapy and immunotherapy to enhance therapeutic response and prevent resistance.
2. Contribution of exosomes and extracellular vesicles to the education of CAFs, MSCs and macrophages by tumor cells: Stromal cells in the TME are educated by tumor cells and polarized toward a pro-tumorigenic function (these cells from being foes learn to become friends of the tumor cells). Extracellular vesicles and in particular exosomes released by tumor cells are captured by stromal cells and contribute to their education not only in primary tumors but also in the pre-metastatic niche. Our laboratory has recently shown (Nakata et al., Journal of Extracellular Vesicles 2017, in press) that exosomes released by NB cells are captured by MSCs and macrophages and contribute to the production of pro-tumorigenic cytokines by these cells. Ongoing work is studying the mechanism involved in the capture of tumor-derived exosomes by MSCs and macrophages with a focus on galectin-3 binding protein and integrins in collaboration with Dr. Lyden at Cornell (NYU) and on identifying ways to inhibit the production of exosomes by tumor cells and its effect on tumor progression and metastasis in pre-clinical mouse models.
3. Role of plasminogen activator inhibitor-1 (PAI-1) in cancer progression: PAI-1 is a serine protease inhibitor which has been shown to have a paradoxically positive effect in cancer progression by promoting angiogenesis and protecting tumor cells from drug-induced apoptosis (Placencio et al., Cancer Res, 2016). More recent work in our laboratory shows that PAI-1 contributes to inflammation in cancer by promoting the recruitment of macrophages into tumors and their polarization (or education) toward a pro-tumorigenic (M2) phenotype.
Funding of the Laboratory: Our laboratory has been funded by the NIH without interruption since 1986. Current funding incudes 2 R01 grants (work on exosomes described under #2, and work on PAI-1 described under #3), and a project in a larger multi-institutional program project grant on neuroblastoma (work under #1).
Environment: Our laboratory is located on the 5th floor of the Smith Research Tower at The Saban Research Institute (TSRI) of Children’s Hospital Los Angeles (CHLA). Our research program is part of the Tumor Microenvironment Program of the USC Norris Comprehensive Cancer Center (USC-Norris) and the neuroblastoma research group of the Children’s Center for Cancer and Blood Diseases at CHLA. Both TSRI and USC-Norris provide a rich and interactive environment for the conduct of innovative research in the area of the TME. We have collaborations with faculty at USC, Cornell, City of Hope, Harvard and Children’s Hospital of Philadelphia. The laboratory has trained 10 graduate students and 25 postdoctoral fellows, many presently working at academic institutions and in industry. Career development of highly motivated and dedicated students is an integral part of the research experience in the laboratory.