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Mao Jia-Yang
TALKING ABOUT
THE
CELLULAR MECHANISM
OF
CHEMICAL CARCINOGENSIS
The word "carcinogensis"
is
used
to describe the
process
of
cancer
for-
mation. Much attention is paid to the
environmental
factors
-
chemical,
physical and biological.
As the causa-
tion
is mostly
multiJactorial
and
the
la-
tent period
is
very long, the progress of
cancer causation studies
is
slow
and
many theories abound.
Chemical
carcinogensis has
3
main steps, initia-
tion,
promotion and development. Suf-
ficient
amounts
of
chemical carcino-
gens can cause cancer
on
it own;
in
lesser quantities, there
is
at least initia-
tion. Best-known carcinogens are ciga-
rette smoke, aflatoxin, chemicals
in
betel nut
chewing, arsenic,
chromium,
nickel compounds, coal
lar
and asbes-
tos
etc. There are 3 main theories of
cellular
mechanism
for
chemical
carcinogensis: genetic, non-genetic and
oncogene/proto-oncogene. Oncogenes
would transform cells to cancer ones
il
activated; on the other hand, the deac-
tivation of proto-oncogenes would also
transform cells
to
cancer ones. Most
probably, chemical carcinogensis
in-
volves
more than one mechanism and
not to
the exclusion
of
the others. Much
work must
be
undertaken to solve such
highly complex issues.
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