 hile caffeine's role as a carcinogen
is widely debated, a new study suggests that caffeine may act as an advocate
to cancer cells, extending their lives and allowing them to spread throughout
the body.
 A Brigham Young University researcher
found that while it doesn't fit the classic model of a carcinogen one that
damages healthy cells in some circumstances, caffeine may protect cancer
cells from death.
"Cancer is a disease where cell
division has gone out of control. In some cases, the cell does not know
how to die. We have found that caffeine may inhibit the apoptotic mechanism
the cell's own defensive mechanism and keep damaged cells alive when they
should die," says microbiologist Kim O'Neill of BYU's Cancer Research
Center in Provo, UT. The report is published in the December 1997 issue
of Cancer Letters.
O'Neill says the study is interesting
basic science but that it does not provide enough information to determine
whether consuming caffeine poses any health risk.
"This is just a small piece
of work indicating that, under certain conditions, caffeine may suppress
apoptosis or the induction of apoptosis in vitro. However, the relevance
of that may not be known for several years," he says.
One of the body's main defense mechanisms,
the process of apoptosis or "cell suicide" helps eliminate damaged
cells before they threaten the body. Virtually every cell in the body is
pre-programmed to undergo apoptosis when DNA is damaged, or when the cell
is no longer needed. Some cells, such as skin cells, die and are replaced
frequently while others, such as nerve cells, are with the body from birth
to death. Generally, when DNA from a cell is damaged, by chemicals or other
means, the cell's own internal apoptotic mechanism switches on.
"Apoptosis is the efficient
way for a cell to die because it will pass on some of its good contents
to neighboring cells and eliminate damaged cells that could pass on defective
DNA. The apoptotic mechanism allows the cells to protect their DNA, keep
it intact and pure, so damaged DNA won't be passed on to the next generation,"
says O'Neill.
Many new cancer therapies aim to
activate the cell's own preprogrammed "suicide" mechanism to eliminate
cancer cells. By intentionally creating breaks in the DNA, the therapies
send a message to the damaged cells to initiate apoptosis. O'Neill says
that if the cell is not allowed to undergo apoptosis, then cancerous cells
may be allowed to spread, and precancerous cells may be allowed to progress.
"If you had, for example, a
damaged pre-cancerous cell and the cell is saying I've gotta die, I've gotta
die,' and you stop the method by which it can die, then there's a chance
that the cell will become cancerous," says O'Neill.
For the caffeine tests, O'Neill dosed
leukemia cells with caffeine and then followed a common heat shock procedure
designed to induce cell death. Under normal conditions, the test would show
breaks in the DNA, followed by a sequence of events that lead to cell death.
But when the cancer cells were boosted with caffeine before receiving the
deadly heat shock, they refused to die.
"Normally by exposing cells
to heat shock for about an hour, 12 hours later those cells will undergo
apoptotic death. By adding caffeine to the medium, you prevent the death
of the cancer cells and therefore give them protection against this programmed
cell death. Since they appear unaffected by the heat shock, the cancerous
cells can continue to replicate," he says.  | 
byu.edu. See also http://www.byu.edu/news/Jan/caffeine.html.