Test 4. Lecture 39 Flashcards
Cancer results from a ___________ that
govern normal cell behavior.
Cancer cells grow and divide in an uncontrolled manner, spreading
throughout the body and interfering with the function of normal tissues
and organs.
The loss of growth control exhibited by cancer cells is the net result of
accumulated abnormalities in multiple cell regulatory systems.
It is reflected in several aspects of cell behavior that distinguish cancer
cells from their normal counterparts
breakdown of the regulatory mechanisms
There are more than ______ of cancer
100 types
A _________is any abnormal proliferation of cells.
tumor
___________ remain CONFINED TO ORIGINAL LOCATION neither invading surrounding
normal tissue nor spreading to distant body sites.
Benign tumors
A ___________ can
- invade surrounding normal tissue and
- spread throughout the body via the circulatory or lymphatic systems (_________).
Only malignant tumors are properly referred to as cancers
malignant tumor
metastasis
Most cancers are in three main groups
carcinomas
sarcomas
leukemias and lymphomas
Tumors are further classified according to _________
tissue of origin and
type of cell involved
_________—malignancies of epithelial cells (about 90% of
human cancers)
Carcinomas
___________—solid tumors of connective tissue such as muscle,
bone, cartilage, and fibrous tissue (rare in humans).
Sarcomas
________ and __________ arise from the blood-forming cells
and immune system cells, respectively.
Leukemias
lymphomas
Only a few types of cancer occur frequently.
The four most common cancers are ____,______,______,_______
prostate, breast, lung, and colon/rectum
________, by far the most lethal, is responsible for nearly 30% of all cancer
deaths.
Lung cancer
____________, by far the most lethal, is responsible for nearly 30% of all cancer
deaths.
Lung cancer
A fundamental feature of cancer is\_\_\_\_\_\_\_\_— tumors develop from single cells that begin to proliferate abnormally.
The single-cell origin has been demonstrated by analysis of X chromosome
inactivation patterns.
tumor clonality
At the cellular level, development of cancer is a multistep process: Mutation and selection for cells with progressively increasing capacity for \_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_
proliferation, survival, invasion, and
metastasis.
___________: mutation leads to abnormal proliferation of a single cell,
which grows into a population of clonal
tumor cells.
Tumor initiation
_________: additional mutations
occur within cells of the tumor population.
Tumor progression
velopment and Causes of Cancer
Cancer cells have characteristic properties that distinguish them
from normal cells and contribute to malignancy: (8)
- Uncontrolled proliferation
- Reduced dependence on growth factors
- Reduced cell adhesion molecules
- Secretion of proteases
- Promotion of angiogenesis
- Abnormal differentiation
- Failure to undergo apoptosis
- Capacity for unlimited replication
In culture, normal cells display ____________:
They proliferate until reaching a finite cell density, determined partly by availability
of growth factors.
They then cease proliferating and are arrested in the G0 stage of the cell cycle.
Cancer cells are not restricted by growth factor availability or cell–cell contact.
They don’t respond to the signals that cause normal cells to cease proliferation, but
grow to high densities in culture.
density-dependent inhibition
Normal fibroblasts show contact inhibition:
They migrate across a culture dish until making contact with a neighboring cell.
_________ cells adhere to each other, forming an orderly array.
_________ cells continue moving after contact, migrating over adjacent cells, growing in
disordered, multilayered patterns.
Normal
Tumor
Many cancer cells can grow in the absence of growth factors required by normal
cells.
Some cancer cells produce growth factors that stimulate their own proliferation
(___________).
Reduced growth factor dependence can also result from abnormalities in intracellular
signaling systems.
autocrine growth stimulation
Cancer cells are less regulated by cell– cell and cell–matrix
interactions.
Most cancer cells are less adhesive than normal cells, due to
reduced expression of cell surface adhesion molecules.
Loss of__________ is important in development of carcinomas
(epithelial cancers).
Reduced adhesion molecules make cancer cells less restrained by
interactions with other cells and the matrix, contributing to their
ability to invade and metastasize.
Many tumor cells are rounder than normal; they are less firmly attached to either the matrix or neighboring cells.
E-cadherin
Cancer cells secrete _____that digest extracellular matrix
components, allowing them to invade adjacent normal tissues.
Example: Proteases that digest collagen allow carcinomas to
penetrate the basal laminae and invade underlying connective
tissue.
proteases
Cancer cells secrete growth factors that promote formation of
new blood vessels (___________).
angiogenesis
When a tumor reaches about a million cells, new blood vessels
are needed to supply oxygen and nutrients.
The new capillaries are easily penetrated by tumor cells,
contributing to metastasis
general
Growth of leukemias, and some solid tumors, may be driven by
proliferation of a subpopulation of cancer stem cells, rather
than proliferation of all cells in the tumor.
Chronic myeloid leukemia arises from oncogenic transformation
of the hematopoietic stem cells.
Many cancer cells fail to undergo ______________or ____ and have longer life spans than normal cells.
Tumor cells are often able to survive in the absence of growth
factors required by normal cells
programmed cell death or
apoptosis
Normal cells also undergo apoptosis following DNA damage,
while many cancer cells do not.
This contributes to resistance of cancer cells to irradiation and
many chemotherapeutic drugs, which act by damaging DNA.
Normal cells have limited amounts of telomerase and gradually
lose telomeres, leading to cessation of replication.
Cancer cells express high levels of __________, allowing them to
maintain chromosome ends for an indefinite number of
divisions.
telomerase
