Cancer Characteristics L25

Cancer Characteristics L25 - Chapter
11
...

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Unformatted text preview: Chapter
11
 Cancer
Characteris.cs
 Signal
Transduc.on
 Signal
transduc.on
is
the
process
by
which
cells
communicate
with
other
cells
 and
with
their
environment
 –  cells
need
to
be
aware
of
food,
toxins
and
neighboring
cells
 surrounding
them
 External
signals
translated
into
a
cellular
response
 –  for
example,
if
a
toxin
is
present
in
the
environment,
a
cell
needs
to
 detect
the
toxin
and
then
produce
defenses
against
the
toxin
 External
signal
 Cell

 response
 Ac.n
Cytoskeleton
 The
ac.n
cytoskeleton
is
a
network
of
proteins
in
a
cell
 –  serves
as
a
structural
frame
or
support

 –  helps
provide
cell
shape
 The
ac.n
cytoskeleton
is
involved
in
many
cellular
processes
 –  adhesion
 –  mo.lity
 –  chemotaxis
or
directed
cell
movement
 –  cancer
progression
and
metastasis
 Cancer
 Cancer
is
the
leading
cause
of
death
in
the
United
States.
 Nearly
one‐third
of
us
will
develop
cancer
in
our
life.mes.
 Cancer
is
not
a
single
disease
 –  more
than
100
specific
diseases
are
lumped
together
under
the
term
 cancer
 Cancer
 Our
bodies
produce
cancerous
cells
each
day,
but
most
are
killed
by
our
 immune
system
 Cancer
cells
have
unlimited
poten.al
to
replicate
 –  normal
cells
are
programmed
to
die
if
their
DNA
is
damaged
or
if
they
 replicate
too
many
.mes
 Programmed
cell
death
is
called
apoptosis
 –  cancer
cells
avoid
apoptosis
and
become
“immortal”
 Characteris.cs
of
Cancer
Cells
 Cancer:
uncontrolled
cell
replica.on
due
to
a
breakdown
in
the
normal
cell
 regula.on
mechanisms
 –  cancer
cells
either
disregard
or
don’t
receive
the
chemical
signals
that
 tell
them
it
is
.me
to
stop
dividing
and
die
 Cancer
cells
lack
differen.a.on
 –  no
specified
func.on
or
contribu.on
to
the
overall
func.oning
of
a
 par.cular
body
part
 –  no
homeosta.c
func.on
in
the
body
 –  have
abnormal
nuclei
and
chromosomes
 Characteris.cs
of
Cancer
Cells
 Normal epithelial
cells
of
the
cervix
 Regular shaped cells Small nucleus located in center Cancerous
epithelial
cells
of
the
cervix
 Irregular shaped cells Very large nucleus Tumor‐suppressor
Genes
and
 Protooncogenes
 Tumor‐suppressor
genes:
stop
or
arrest
growth

 Proto‐oncogenes:
growth
promoters
 –  these
can
suffer
random
muta.ons
 –  if
both
the
tumor
suppressor
genes
and
proto‐oncogenes
in
the
same
 cell
are
altered,
the
result
could
be
cancer
 Tumor‐suppressor
Genes
and
 Protooncogenes
 Tumor‐suppressor
gene
muta.ons

 –  no
longer
regulates
the
cell
cycle
 –  will
not
promote
apoptosis
 –  such
muta.ons
are
referred
to
as
“loss‐of
func.on”
muta.ons
 Proto‐oncogenes
muta.ons
 –  form
oncogenes,
or
genes
that
cause
cancer
 –  disrupt
cellular
func.on
 –  because
there
are
many
proto‐oncogenes
in
each
cell,
it
is
possible
to
 form
many
oncogenes
in
one
cell
 –  the
more
oncogenes
in
one
cell,
the
worse
off
that
cell
will
be

 TP53
 TP53 is
a
tumor‐suppressor
gene
which
gives
direc.ons
for
the
making
the
 protein
p53
 Many
cancer
cells
can
have
faulty
or
mutated
TP53
genes
 –  cells
achieves
a
kind
of
immortality,
since
they
do
not
receive
or
 respond
to
the
signals
telling
them
to
die
 p53
serves
as
a
general
manager
for
cell
func.on
 –  it
halts
cell
division
in
an
abnormal
cell
unless
and
un.l
any
damaged
 DNA
can
be
repaired
 –  if
it
cannot
be
repaired,
the
TP53
gene
and
its
protein,p53,
ini.ate
a
 series
of
physiological
changes
that
ul.mately
lead
to
the
cell’s
death
 P53
and
the
Cell
Cycle
 P53

 reference.canadaspace.com/search/p53/ Telomeres
 Telomeres
are
.ny
pieces
of
DNA
located
at
the
.ps
of
chromosomes
and
are
 maintained
by
an
enzyme
called
telomerase
 –  each
.me
a
cell
replicates,
a
liSle
bit
of
the
telomere
is
snipped
off
 –  a
typical
cell
replicates
50
or
60
.mes
before
the
en.re
telomere
is
 gone
 –  at
that
point
the
cell
stops
replica.ng,
and
eventually
it
wears
out
and
 dies

 If
telomerase
is
present
in
the
cell,
the
telomere
is
repaired
aVer
every
 division,
and
the
cell
can
con.nue
to
divide
indefinitely
 –  the
cell
that
develops
the
ability
to
maintain
telomerase
in
its
 cytoplasm
lives
“forever,”
and
is
on
its
way
to
being
a
cancerous
cell
 –  many
cancer
cells
con.nue
to
have
telomerase
 Tumor
Forma.on
 A
tumor
is
a
group
of
cancer
cells
 –  in
addi.on
to
uncontrolled
cell
division,
cancer
cells
lose
normal
 inhibi.ons
and
are
more
adhesive
to
surrounding
cells
 –  cancer
cells
adhere
to
other
cells
and
form
a
tumor
 Benign
tumors
 –  these
tumors
do
not
spread
to
other

 Malignant
tumors
are
harmful
 –  these
tumors
invade
other
.ssues
 –  can
spread
throughout
body

 Cancer
Progression
 Cancer
Progression
 Once
they
have
overcome
the
body’s
defenses,
cancer
cells
can
exploit
their
 advantage

 –  cancer
cells
con.nue
to
grow
and
mul.ply
unchecked
 –  carry
many
muta.ons
which
originate
from
a
single
muta.on
in
a
 control
gene
 –  these
mutated
cells
can
successfully
outcompete
normal
cells
for
 space
and
nourishment
 –  carcinogenesis,
or
cancer
development,
has
begun
 Cancer
Progression
 When
a
malignant
cancerous
growth
reaches
about
1
million
cells
 (approximately
1
or
2
millimeters
in
diameter),
the
cells
in
the
interior
can
 no
longer
receive
enough
nutrients
 –  cells
begin
to
deposit
waste
products
within
the
cell
cluster
 –  this
ball
of
cells
is
called
a
carcinoma
in situ (“cancer
in
place”)
 –  it
needs
its
own
blood
supply

 –  it
produces
its
own
growth‐enhancing
proteins
and
secre.ng
 chemicals
called
angiogenic
compounds
that
lure
blood
vessels
into
 the
tumor
 Angiogenesis
is
the
process
by
which
new
blood
vessels
are
formed
to
feed
a
 tumor
 –  once
it
has
a
blood
supply,
the
tumor
becomes
immortal
 –  unless
it
is
cut
out,
killed
with
chemicals,
damaged
by
radia.on
or
 another
substance,
or
starved
of
its
nutrient
supply,
the
tumor
will
 grow
and
spread
un.l
it
kills
its
host
 Carcinogenesis
 Carcinogenesis
 Cancer
Progression
 Cancer
tumors
can
invade
almost
any
body
.ssue
 –  from
skin
and
bone
to
organs
like
the
lungs,
liver,
and
intes.ne
 Once
a
tumor
has
become
firmly
established
in
such
a
“primary
site,”
 cancerous
cells
oVen
break
away
from
the
original
massand
travel
 through
the
bloodstream
or
lymph
 –  metastasis
is
the
process
by
which
the
original
cancerous
tumor
 spreads
throughout
the
body
 –  traveling
cells
are
deposited
at
“secondary
sites,”
where
other
tumors
 may
develop
 –  metasta.c
tumors
may
con.nue
to
grow
even
if
the
primary
tumor
is
 killed
or
removed
 ...
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This note was uploaded on 10/27/2010 for the course BIOL 125 taught by Professor Klein during the Spring '10 term at CUNY Hunter.

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