Download Diapositiva 1

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)
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 apoptosis
3. The avoid limitations to proliferation, such
as differentiation and senescence
4. They are genetically unstable
5. 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