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 originThey may grow large, but their growth rate is slower

than that of malignant tumorsThey usually do not cause death unless their location

impairs the function of a vital organMALIGNANT tumors grow rapidly are likely to

undergo metastasis (See table 20-2)

Benign vs malignant

Epithelial cells = carcinomas

Connective tissues or muscle = sarcomas

Hemopoietic cells = leukemias

Pigments producing cells of the skin = melanoma

6 key behaviors of cancer cells

1. They disregard the external and internal signals that regulate cell proliferation

2. They are resistant to apoptosis3. The avoid limitations to proliferation, such

as differentiation and senescence4. They are genetically unstable5. They are invasive (escape home tissue)6. The metastasize (survive and proliferate in

foreign tissues)

Clonal Evolution

Genetic Instability and Tumor Progression

Normal and deranged control of cell production from stem cells

Dominant and recessive cancer genes

Ways to make a proto-oncogene overactive

The genetic mechanisms underlying retinoblastoma

Rb Protein

Major signaling pathways relevant to cancer

p53

Telomerase is reactivated in Human cancers