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Topic 28-cancer- reading summary

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Western University
Biochemistry 2280A
Eric Ball

Topic 28: Cancer reading (parts of Ch. 20) Our bodies can renew and repair themselves. However, the mechanism can go wrong leading to disruption of the body’s structure. Cancer is now the major cause of death in NA. ~ 1:3 to1:4 will die of cancer. Causes and Mechanism of cancer: Cancer Cell Proliferate, Invade & Metastasize Individual cell adjust its needs according to the need of the whole organism. Divide or not, live or kill itself, maintain appropriate specialized character, occupy its proper place. If 1 cell misbehaves  no harm, but if the cell has genetic alteration that allows it to survive and divide when it should not, producing many more cell of its kind. The whole tissue organism may be disrupted. Types of cell misbehaviour that contribute to cancer progress Cancer cells are defined by 2 heritable properties: 1- proliferate with less regard to the normal constraints, 2- invade and colonize areas reserved for other cells.  both make it lethal. Cells with property (1) only are benign (remain clustered in a single mass), it can be removed surgically. Malignant tumors invade surrounding cells, enter the bloodstream or lymphatic vessels and form secondary tumors (metastases) at other sites. spreadharder to cure. Metastasis: Cells of primary tumor in an epithelium cross the basal lamina  migrate through connective tissue get into bloodstream or lymphatic vessels exit and survive in a new site. Preventable Causes of Cancer: Epidemiology Factors in Env Trigger cancer and help it to progress. It is where ppl Live not where they were born that determine their risk. e.g.: cervical cancer: virus  preventable by vaccine? (still under research) Obesity:  risk. Smoking: 30% of all cancer, and 90% of lung cancer, bladder. Ionizing radiation mutagens (cause change in DNA’s nucleotides) Carcinogens mutagens (cause change in DNA’s nucleotides) Cancer Develop by an Accumulation of Mutations 1 Cancer is genetic; it is a consequence of pathological changes in DNA info. The mutations are usually somatic mutations (occurs in individual cells of the mature body), not germ-line mutations (handed down via the germ cells from which the entire multicellular organism develops). Mutations will occur spontaneously as a result of inaccurate DNA replication and repair. Spontaneous mutations are 10 mutations/gene/cell division w/o involvement of external mutagens. With 10 cell division in the human body during life time  10 mutations9 are possible; however, it take more than one mutation to turn a normal cell into a cancer cell (over many years). Cancer is typicaaly a disease of old age. Most human cancers do not only contain many mutations but are also genetically unstable; results from mutation that 1-interfere with accurate replication of the genome mutation rate, 2-efficiency of DNA repair, 3-occurrence of chromosome breaks and rearrangements resulting in a grossly abnormal and unstable karyotype. Cancer Properties Mutations that lead to cancer make natural selection favors mutant cells carrying mutations to enhance cell proliferation and survival, regardless of effects on neighbors. Nun-mutagenic environmental (life style factors), such as obesity, favor the development of cancer by altering the selection pressures that operates in the tissue of the body, helping mutant cells to survive and proliferate  as a result, abnormal cells required for cancer will emerge. A cancer cell must acquire a whole range if abnormal properties (subversive new skills) as it evol
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