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Harrison's Internal Medicine Chapter 80. Cancer Cell Biology and Angiogenesis Cancer Cell Biology and Angiogenesis: Introduction Two characteristic features define a cancer: unregulated cell growth and tissue invasion/metastasis. Unregulated cell growth without invasion is a feature of benign neoplasms, or new growths. Cancer is a synonym for malignant neoplasm. Cancers of epithelial tissues are called carcinomas; cancers of nonepithelial (mesenchymal) tissues are called sarcomas. Cancers arising from hematopoietic or lymphoid cells are called leukemias or lymphomas. Cancer is a genetic disease. The malignant phenotype often requires mutations in several different genes that regulate cell proliferation, survival, DNA repair, motility, invasion,. | Chapter 080. Cancer Cell Biology and Angiogenesis Part 1 Harrison s Internal Medicine Chapter 80. Cancer Cell Biology and Angiogenesis Cancer Cell Biology and Angiogenesis Introduction Two characteristic features define a cancer unregulated cell growth and tissue invasion metastasis. Unregulated cell growth without invasion is a feature of benign neoplasms or new growths. Cancer is a synonym for malignant neoplasm. Cancers of epithelial tissues are called carcinomas cancers of nonepithelial mesenchymal tissues are called sarcomas. Cancers arising from hematopoietic or lymphoid cells are called leukemias or lymphomas. Cancer is a genetic disease. The malignant phenotype often requires mutations in several different genes that regulate cell proliferation survival DNA repair motility invasion and angiogenesis Table 80-1 . Cancer-causing mutations often activate signal transduction pathways leading to aberrant cell proliferation and perturbations of tissue-specific differentiation programs. The normal cell has protective mechanisms that lead to the repair of DNA damage that occurs during DNA synthesis and mitosis and in response to environmental mutagens these repair pathways are often abnormal in cancer cells. When a normal cell has sustained too much damage to repair the cell activates a suicide pathway to prevent damage to the organ. These cell death pathways are also commonly altered in cancer cells leading to the survival of damaged cells that would normally die. Cancer cells often exist under conditions of low oxygen tension hypoxia and nutrient deprivation and selective pressure leads to the outgrowth of neoplastic variants that can survive under these conditions through the upregulation of a series of hypoxia-inducible genes see below . The acquisition of novel phenotypic characteristics includes those that facilitate invasion and metastasis such as the ability to break through basement membranes migrate through the extracellular matrix and into the vascular .
