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PROLIFERAZIONE CELLULARE E RESISTENZA AI FARMACI. CANCER. Cancer is characterized by abnormal, unrelated cell proliferation Cancer invades healthy tissues and compete with normal cells for oxygen, nutrients, and space
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PROLIFERAZIONE CELLULARE E RESISTENZA AI FARMACI
CANCER • Cancer is characterized by abnormal, unrelated cell proliferation • Cancer invades healthy tissues and compete with normal cells for oxygen, nutrients, and space • Abnormal cells reproduce in the same way as normal cells, but they do not have the regulatory mechanisms to control growth • The abnormal cell growth proliferates in an uncontrolled and unrestricted way.
CANCER • Tumors are also classified according to their cell of origin and whether their growth is benign or malignant • BENIGN tumors remain at their site of origin • They may grow large, but their growth rate is slower than that of malignant tumors • They usually do not cause death unless their location impairs the function of a vital organ • MALIGNANT tumors grow rapidly are likely to undergo metastasis (See table 20-2)
Epithelial cells = carcinomasConnective tissues or muscle = sarcomasHemopoietic cells = leukemiasPigments producing cells of the skin = melanoma
6 key behaviors of cancer cells • They disregard the external and internal signals that regulate cell proliferation • They are resistant to apoptosis • The avoid limitations to proliferation, such as differentiation and senescence • They are genetically unstable • They are invasive (escape home tissue) • The metastasize (survive and proliferate in foreign tissues)
Clonal Evolution
Normal and deranged control of cell production from stem cells
Telomerase is reactivated in Human cancers