title: Pathophysiological mechanisms of death resistance in colorectal carcinoma.
abstract: Colon cancers develop adaptive mechanisms to survive under extreme conditions and display hallmarks of unlimited proliferation and resistance to cell death. The deregulation of cell death is a key factor that contributes to chemoresistance in tumors. In a physiological context, balance between cell proliferation and death, and protection against cell damage are fundamental processes for maintaining gut epithelial homeostasis. The mechanisms underlying anti-death cytoprotection and tumor resistance often bear common pathways, and although distinguishing them would be a challenge, it would also provide an opportunity to develop advanced anti-cancer therapeutics. This review will outline cell death pathways (i.e., apoptosis, necrosis, and necroptosis), and discuss cytoprotective strategies in normal intestinal epithelium and death resistance mechanisms of colon tumor. In colorectal cancers, the intracellular mechanisms of death resistance include the direct alteration of apoptotic and necroptotic machinery and the upstream events modulating death effectors such as tumor suppressor gene inactivation and pro-survival signaling pathways. The autocrine, paracrine and exogenous factors within a tumor microenvironment can also instigate resistance against apoptotic and necroptotic cell death in colon cancers through changes in receptor signaling or transporter uptake. The roles of cyclooxygenase-2/prostaglandin E2, growth factors, glucose, and bacterial lipopolysaccharides in colorectal cancer will be highlighted. Targeting anti-death pathways in the colon cancer tissue might be a promising approach outside of anti-proliferation and anti-angiogenesis strategies for developing novel drugs to treat refractory tumors.
authors.affiliation: Ching-Ying Huang, Linda Chia-Hui Yu, Graduate Institute of Physiology, National Taiwan University College of Medicine, Taipei 100, Taiwan.
authors.forename: Ching-Ying
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Ching-Ying Huang, Linda Chia-Hui Yu, Graduate Institute of Physiology, National Taiwan University College of Medicine, Taipei 100, Taiwan.
authors.forename: Linda Chia-Hui
authors.initials: LC
authors.lastname: Yu
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D019008:Drug Resistance, Neoplasm; D006801:Humans; D009336:Necrosis; D015398:Signal Transduction / Q000187:drug effects; D059016:Tumor Microenvironment
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D018797:Cell Cycle Proteins
keywords: Anti-apoptosis; Anti-necroptosis; Chemoresistance; Colon cancer; Cytoprotection; Tumorigenesis