Biomedical Engineering Reference
In-Depth Information
Table 2
. Comparison of the process by which a cancer cell acquires the traits
necessary for metastasis and how humans successfully colonize
Human organism—
Trait to allow growth
Cancer cell—clonal
civilization expansion
and dissemination
expansion (unconscious)
(conscious)
Unlimited replicative
Asexual reproduction,
Sexual reproduction, desire
potential
activation of telomerase
for survival
Adaptation
Genetic instability, natural
Evolution, natural selectio
selection
Protection from death
Loss of apoptotic pathway
Safety in numbers, city
activation
walls, castles
No growth inhibition
Anchorage independent
Ability to move about as
growth
individuals or groups
without constraint
Nutrient supply
Stimulate new blood
Building of water reservoirs
vessel growth
and aqueducts to bring
water to the population
Population expansion
Activation of proteases to
Expansion/invasion into
break down surrounding
neutral territory
tissue
Evasion of enemies
Evasion of the immune
Avoiding contact with
surveillance system, e.g., as
hostile forces that want to
cells circulate prior to
prevent colonization, e.g.,
establishing themselves
warships trying to prevent
in a new organ
colonial expansion
Successful colonization
Adaptation to the use of
Building a new site,
growth factors in the new
learning to eat new foods,
environment and applying
and applying all of the traits
all of the traits above in a
outlined above in a new
new environment
environment
clock, termed telomeres, built onto the end of each chromosome (14). Telomeres
are specific strands of DNA that shorten with each cell division. At a critical
shortened length, the cells undergo apoptosis, or programmed cell death. Cancer
cells reactivate an enzyme, telomerase, that maintains the length of telomeres
with each cell division by adding base pairs back onto the telomeres, thereby
maintaining length integrity.
3.2. Adaptation, Mutation, and Natural Selection
A fundamental characteristic of cancer is the generation of tumor cell het-
erogeneity, i.e., cells with multiple mutated phenotypes, through a mechanism of
