Intrinsic metabolic as well as extrinsic therapeutic stress during conventional cancer treatment induces cancer cells to overexpress Damage-Associated Molecular Pattern molecules (DAMPs). Their increased release into necrotic or injured regions within the tumor microenvironment regulates cell death (e.g. apoptosis) and cell survival (e.g. autophagy) in both adjacent and distant (systemic) tissues. The prototypic DAMP, High Mobility Group Box 1 (HMGB1), is a highly conserved nuclear protein with multiple intracellular and extracellular functions, including transcriptional regulation and modulation of inflammation and immunity. We recently demonstrated that HMGB1 is an essential regulator of autophagy, a cellular catabolic process that facilitates the degradation of cytoplasmic components using the lysosomal machinery. Based on our findings, we hypothesize that our central hypothesis is that HMGB1 overexpression and release in response to cancer therapy activates autophagy thereby increasing resistance to therapy and promoting tumor growth. To test this hypothesis, genetic, biochemical and cell biological studies will be utilized to characterize whether and how HMGB1 increases resistance of pancreatic cancer cells to chemotherapeutic agents such as gemcitabine through autophagic regulation. The experimental approach to specifically target HMGB1 will utilize novel HMGB1 pancreatic conditional knockout mice that we have created, HMGB1 neutralizing antibodies, and HMGB1 specific shRNA. The long term goal of this project is to improve the outcome of patients receiving cancer therapies by developing a novel strategy to target pancreatic cancer, a disease associated with low survival rates as well as a high degree of intrinsic and/or acquired resistance to therapy. These studies will provide new insights into HMGB1 signaling and the role of autophagy in tumor therapy. This deeper understanding will be used to improve the effectiveness of existing pancreatic cancer therapies.
During the past several years, it has become increasingly clear that the understudied cellular process of autophagy is an important regulator of cancer development and response to treatment. Increasing evidence suggests that autophagy is an important resistance mechanism in established cancers in response to chemotherapy, radiation therapy, and immunotherapy. The focus of the proposed study is to investigate the molecular basis of sustained autophagy in the setting of tumor treatment with a specific focus on a novel pro- autophagic protein, HMGB1, which contributes to the efficacy of various anti-cancer agents and provides a rationale for the manipulation of autophagy during cancer treatment.
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