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(By the author of "Cancer Chronicles", a book I reviewed a while back:
http://www.counterpunch.org/2014/08/29/cancer-politics-and-capitalism/)
NY Times, July 28 2015
Cellular ‘Cheaters’ Give Rise to Cancer
by George Johnson
Maybe it was in “some warm little pond,” Charles Darwin speculated in
1871, that life on Earth began. A few simple chemicals sloshed together
and formed complex molecules. These, over great stretches of time,
joined in various combinations, eventually giving rise to the first
living cell: a self-sustaining bag of chemistry capable of dividing and
spawning copies of itself.
While scientists still debate the specifics, most subscribe to some
version of what Darwin suggested — genesis as a fortuitous chemical
happenstance. But the story of how living protoplasm emerged from
lifeless matter may also help explain something darker: the origin of
cancer.
As the primordial cells mutated and evolved, ruthlessly competing for
nutrients, some stumbled upon a different course. They cooperated
instead, sharing resources and responsibilities and so giving rise to
multicellular creatures — plants, animals and eventually us.
Each of these collectives is held together by a delicate web of
biological compromises. By surrendering some of its autonomy, each cell
prospers with the whole.
But inevitably, there are cheaters: A cell breaks loose from the
interlocking constraints and begins selfishly multiplying and expanding
its territory, reverting to the free-for-all of Darwin’s pond. And so
cancer begins.
Although we are getting better at preventing or controlling these
rebellions, cancer is an inescapable consequence of multicellularity. A
fascinating review, published last month in Philosophical Transactions
B, shows how cancer and similar kinds of cellular cheating arise not
only in mammals, birds, reptiles, fish, insects and other animals, but
also in plants, fungi — in most, if not all, multicellular organisms.
In “Cancer Across the Tree of Life: Cooperation and Cheating in
Multicellularity,” researchers at the Institute for Advanced Study in
Berlin show how maverick cells in species after species engage in the
kind of pathological behavior that can bring down any society.
In a healthy organism, a cell replicates only as frequently as needed to
maintain the population and allow for modest growth. Cancer cells begin
reproducing wildly, consuming more than their share of resources and
spewing poisons that degrade the environment and reshape it to their own
advantage.
Through a process called differentiation, normal cells specialize,
becoming skin cells, nerve cells, bone cells and so forth. There is a
division of labor. But cancer cells “dedifferentiate,” abandoning their
assigned roles and pursuing a course beneficial only to themselves.
Under normal circumstances, a cell that goes berserk is quickly
eliminated through a mechanism called programmed cell death, or cellular
suicide. Cancer cells defeat this safeguard. They refuse to die.
No wonder cancer has become a metaphor for human excess — overpopulation
and consumption, environmental pollution, the concentration of resources
among a hyperacquisitive 1 percent.
The paper in Philosophical Transactions describes cancerlike phenomena
in almost every niche of the biosphere. There is even a kind of growth,
calicoblastic epithelioma, occurring among colonies of corals.
A photograph included in the paper shows a tumorous protrusion on the
mushroom Agaricus bisporus. In another image, the top of a saguaro
cactus erupts in elaborate curlicues of uncontrolled growth called
fasciations — pathological but so visually arresting that “crested
cacti” are valued by collectors.
The writhing distortions reminded me of those I’ve induced in weeds I
sprayed with an herbicide called triclopyr. According to the
manufacturer’s literature, the chemical is believed to work by mimicking
growth hormones called auxins, causing plant cells to crazily multiply.
It’s like chemotherapy in reverse, inducing something akin to cancer.
Not all biologists would agree that every instance described in the
paper should be classified as cancerlike. What is clear from the
abundance of examples is that multicellular life is a continual struggle
between competition and cooperation. Tip the balance too far, and the
result might be a malignancy.
In the long run of evolution, the trade-offs between cellular freedom
and communalism have frequently paid off. Multicellularity, imperfect as
it must be, can be so advantageous that it has evolved independently a
number of times during the history of the biosphere.
Most of Earth’s biomass still consists of individual actors — bacteria
and other single-celled creatures. Often, however, these microbes also
cede some of their independence, banding into primitive collectives,
like the invisible biofilms that coat surfaces of hospital equipment or
thrive in our mouths as dental plaques. These mutual support societies
can be all but invincible to antibiotics.
Yet here too, some research suggests, cooperation can give rise to
cheating. Taking advantage of the sustenance and shelter provided by the
biofilm, some bacteria will squander resources and thrive at the expense
of the others — a microscopic tragedy of the commons.
Even cancer cells, once they gain the upper hand, may also begin
cooperating with one another — to the benefit of the tumor and to the
peril of its host.
As the cancerous cells divide and mutate, they diverge into separate
lineages, or “subclones,” each with different abilities. In a deadly
symbiosis, one family of cells might manufacture a substance that
benefits the others, which in turn makes other chemicals the tumor needs
to grow and colonize remote parts of the body.
Through a complex chemical dance, cancer cells can even beguile healthy
cells into doing their bidding, acting in ways that promote the
malignancy. It’s a strategy all too familiar in life: cooperate just
enough to gain your competitors’ trust and then betray them for your own
advantage.
In the end, there are no winners. The cancer destroys its own ecosystem
and dies with its host.
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