Biography
Dr. Takuma Hayashi
Dr. Takuma Hayashi
National Hospital Organization Kyoto Medical Center, Japan
Title: Initialization of epithelial cells by tumor cells in a metastatic microenvironment
Abstract: 
The development of metastasis is a multistage process with several rate-limiting steps. The interaction between stromal cells and infiltrating tumor cells is an important step in metastatic colonization. Cancer cells that travel to a distant site may prompt normal neighboring cells at that location to create a tumor-promoting microenvironment. We previously examined niches for promoting metastatic colonization using the generation of human-in-mouse ovarian cancer xenograft models, i.e., CD34+ lineage ovarian cancer stem-like cells were injected into the mammary fat pads of BALB/c nu/nu mice. CD90 may be used as a marker for a number of stem cells. S100A4 secreted by ovarian cancer cells, supports tumorigenesis by stimulating angiogenesis. Pathological examinations revealed the existence of S100A4-negative and CD90-positive stem-like cells in normal neighboring alveolar epithelial cells. Similarly, the initialization of mimicry may represent the incomplete differentiation of normal alveolar epithelial cells towards the stem-like lineage. Our results also support the presence of cancer-associated parenchymal cells that exhibit stem cell-like features. The result showing that ovarian cancer cells form a metastatic niche near alveolar stem cells is reminiscent of a previous finding demonstrating that when prostate cancer cells metastasize to bone, they settle near stem cells in bone marrow, which promotes the development of a metastatic environment that supports tumor growth. The therapeutic targeting of metastatic cells is the most challenging goal in clinical oncology. The prevention of de novo niche formation may be a novel strategy for the clinical treatment of metastatic disease.
Biography: 
Dr. Hayashi is professor at Shinshu University Graduate School of Medicine since 2002, and also Section Head, National Hospital Organization Kyoto Medical Center, Japan. He received his Ph.D. from Inst. for Medical Science, University of Tokyo in 1994. He was research training as a resident staff in Virology Division, at National Cancer Center, Tokyo Japan for 3 years until 1994 and joined Whitehead Institute for Biomedical Research (WI)/Mass.Inst.Tech.(M.I.T.) that year. He did postdoctoral training in the laboratory of Dr. Rick A. Young (Membership in the National Academy of Sciences, WI/M.I.T.), and also was a research member of USA Project of AIDS vaccine development (Project Leader: Dr. David Baltimore, Nobel Laureate, Cal.Tech.). After postdoctoral training, he got faculty position Lecture, Mass. General Hospital (MGH)/Harvard Medical School (HMS) in 1997. He has been studying the antigen presentation system by MHC class I with LMP2-deficient mice, under the cooperation of Dr. Susumu Tonegawa (Nobel Laureate, M.I.T.). He identifies diagnostic biomarkers, LMP2, Cyclin B1 and Cyclin E, for malignant tumor, i.e. uterine leiomyosarcoma, and BRCA1 and S100A4 for ovarian carcinoma. Current research focus: molecular approach of tumorigenesis of uterine leiomyosarcoma and ovarian cancer.