Cancer Causes L26

Cancer Causes L26 - 5/7/10...

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Unformatted text preview: 5/7/10 Cancer:
Causes
and
Effects
 Chapter
11
 Cancer:
Causes
 There
is
NO
single
cause
for
an
individual
cancer
 –  many
factors
play
a
role
in
ini8a8ng
and
 promo8ng
cancer
 •  heredity
 •  environment
 •  viruses
 •  diet
 Cancer:
Causes
and
Effects
 Most
cancer
causing
muta8ons
are
the
result
of
the
 body’s
cells
“accidentally”
damaging
their
own
genes
 in
the
normal
course
of
cellular
respira8on
 Cancer:
Ini4ator
and
Promoters
 Ini8ator
 –  Causes
cancerous
changes
in
cellular
func8oning
 Promoter
 –  Increases
likelihood
that
an
ini8ator
will
affect
cellular
 func8oning
 An
ini8ator
needs
to
be
present
to
trigger
change
and
 secondary
muta8ons
necessary
for
cancer
to
develop
in
 these
individuals.
 –  Agents
can
be
ini8ators
and
promoters
 Heredity
and
Cancer
 Numerous
gene8c
markers
predispose
individuals
to
 one
or
another
form
of
cancer

 –  breast
cancer
gene
1
and
2,
or
BRCA1
and
BRCA2,
 are
tumor‐suppressor
genes
 –  Re8noblastoma
gene
or
RB
is
another
tumor‐ suppressor
gene
 –  RET
gene
 Mutated
BRCA1
or
BRCA2
gene
can
be
inherited
from
either
 parent
 –  Mutated
gene
in
every
cell
of
body
 –  Mutated
gene
not
be
expressed;
chance
of
developing
 breast
cancer
are
no
higher
than
rest
of
popula8on
 –  If
second
BRCA1
or
BRCA2
muta8on
occurs,
chances
of
 developing
cancer
increase
over
those
of
the
general
 popula8on
 –  If
the
second
muta8on
develops
in
breast
8ssue
cells,
 the
result
is
breast
cancer;
ovary
=
ovarian
cancer
 Heredity
and
Cancer:
BRCA
 1 5/7/10 RB gene
linked
to
re8noblastoma
=
cancer
of
the
re8na
 –  RB
is
a
tumor‐suppressor
gene
 –  Both
copies
of
RB
must
be
mutated
to
increase
an
 individual’s
risk
of
contrac8ng
this
cancer
 For
some
genes,
only
one
mutated
copy
increases
risk
 of
developing
cancer
 –  Thyroid
cancer
is
greatly
enhanced
if
the
 individual
has
a
muta8on
in
one
copy
of
the
RET gene
present
in
every
cell
 Heredity
and
Cancer:
RB
and
RET Heredity
and
Cancer
 Environment
and
Cancer
 Es8mate
that
more
than
50
percent
of
all
cancers
are
 caused
by
environmental
carcinogens
 –  Carcinogen:
environmental
agent
that
can
cause
 cancer
 –  Environmental
carcinogens
act
by
causing
cellular
 muta8on

 –  Mutated
genes
can
then
be
passed
from
parent
to
 child
in
the
egg
or
sperm,
and
they
may
then
 predispose
the
child
to
developing
cancer
 –  Cause
muta8ons
in
developing
child
 Environment
and
Cancer
 Some
environmental
carcinogens
act
only
as
ini8ators,
 whereas
others
act
as
both
ini8ators
and
promoters
 The
two
most
prevalent
forms
of
environmental
 carcinogens
are
chemicals
and
radia8on
 Environment
and
Cancer
 Tobacco
smoke,
contains
many
chemicals
iden8fied
as
a
 carcinogen
 –  Even
paper
used
in
cigareVes
includes
harmful
chemicals
 that
are
released
when
the
cigareVe
is
burned
 –  Cancer
deaths
linked
to
cigareVe
smoke:
30%
to
80%

 Only
about
2
percent
of
cancer
deaths
are
linked
to
exposure
 to
industrial
pollutants
 –  Majority
of
these
cancers
occur
in
people
who
work
in
 an
industry
that
uses
the
carcinogenic
substances

 –  Not
in
people
whoare
exposed
to
diffuse
environmental
 pollu8on
 Environment
and
Cancer
 2 5/7/10 Environment
and
Cancer
 Pregnant
women
and
fetuses
are
especially
suscep8ble
to
 some
kinds
of
industrial
pollu8on
 –  Ac8ve
cellular
growth
and
differen8a8on
 –  Fetus
affected
by
minute
quan88es
of
carcinogen
 •  Ethics?
 •  Discrimina8on?

 –  GINA:
Gene8c
informa8on
Nondiscrimina8on
Act
 Environment
and
Cancer
 Environmental
radia8on:
 •  Ionizing
and
non‐ionizing
 •  Radon,
a
colorless,
odorless
gas
that
is
released
by
water,
 soil,
and
rocks
in
varying
amounts
and
intensi8es
in
 different
geographic
areas
 •  Nuclear
fuel,
whether
used
to
generate
power
or
to
 produce
bombs,
has
been
linked
to
cancer
 •  Diagnos8c
 Environment
and
Cancer
 Radia8on’s
two
forms:
ionizing
and
non‐ionizing
 –  sunlight
is
most
prevalent
source
of
ionizing
radia8on
 •  over
80
percent
of
skin
cancers
are
caused
by
 exposure
to
higher‐frequency
ultraviolet
B
(UVB)
rays
 of
sunlight
 –  many
people
believe
that
the
non‐ionizing
radia8on
 created
by
electric
power
lines,
household
appliances,
 and
cell
phones
is
also
carcinogenic
 •  currently,
there
is
no
scien8fic
evidence
to
support
 this
no8on
 Environment
and
Cancer
 Take
command
of
a
cell’s
gene8c
machinery
in
order
to
copy
 themselves,
they
can
also
promote
cancerous
muta8ons
 –  Alter
expression
 –  Lysogeny
 –  Weaken
immune
system
 Some
viruses
have
been
linked
to
par8cular
cancers:
 –  human
papilloma
virus
(HPV):

cervical
cancer
 –  Epstein–Barr
virus
(EBV):
lymphoma
 –  Hepa88s
B
and
C
viruses:
liver
cancer
 –  HIV:
non‐Hodgkin’s
lymphoma
and
Kaposi’s
sarcoma
 Viruses
and
Cancer
 Diet
and
Cancer
 Obesity
linked
with
an
increase
(50
percent
or
more)
in
 the
incidence
of
colon
cancer
among
both
men
and
 women
and
(50
percent
or
more)
in
the
risk
of
breast
 and
uterine
cancer
among
women
 Diets
high
in
animal
fat
from
beef,
pork,
and
dairy
foods
 associated
with
an
increased
risk
of
colon
cancer
 3 5/7/10 Diet
and
Cancer
 Nitrites
(converted
into
nitrosamines
are
oien
used
as
 a
preserva8ve
in
luncheon
meats
and
other
foods
 –  Diet
high
in
nitrites
has
been
linked
to
a
higher
risk
 of
cancer
 –  diets
high
in
nitrates

 Smoked
meats,
which
contain
chemical
carcinogens
 similar
to
those
found
in
tobacco
smoke
 Diet
and
Cancer
 Fish
and
mollusks
that
feed
in
waters
contaminated
by
 chemicals
or
heavy
metals
store/incorporate
 carcinogenic
substances
in
their
flesh/organs
 Excessive
alcohol
consump8on
linked
to
increases
in
 many
cancers,
especially
cancers
of
the
mouth,
 throat,
and
esophagus
 –  breast
and
liver
cancers
have
also
been
linked
to
 excessive
alcohol
use
 Certain
foods
may
help
guard
against
cancer
 •  free
radicals
are
generally
detoxified
by
the
body’s
natural
 processes,
but
if
inefficient,
free
radicals
build
up
in
the
 body
and
cause
cellular
damage:
including
to
DNA
 •  an8oxidant
vitamins
counteract
the
effects
of
the
free
 radicals
 –  Green,
leafy
vegetables
contain
a
precursor
to
vitamin
A
 called
beta‐carotene,
which
is
an
an8oxidant

 –  Vitamin
C,
found
incitrus
fruit,
is
another
an8oxidant
 Diet
and
Cancer
 Cancers
 Cancers
are
classified
according
to
their
loca8on
and
the
type
 of
8ssue
in
which
they
appear
 –  carcinomas
are
cancers
of
the
epithelial
8ssues
 –  adenomas
are
cancers
of
the
glandular
8ssues
 –  sarcomas
are
cancers
of
the
connec8ve
and
muscular
 8ssues
 –  blastomas
are
cancers
of
the
embryonic
8ssues
 –  leukemias
are
cancers
involving
the
blood
 –  lymphomas
are
cancers
involving
the
lympha8c
system
 Cancers
 Cancers
 4 ...
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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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