Anoikis,
Dehydroepiandrosterone, Cancer, and Metastasis
Copyright
2011, James Michael Howard, Fayetteville, Arkansas, U.S.A.
“Anoikis
is a form of programmed cell death which is induced by anchorage-dependent cells
detaching from the surrounding extracellular matrix (ECM). Usually cells stay close to the tissue to
which they belong since the communication between proximal cells as well as
between cells and ECM provide essential signals for growth or survival. When
cells are detached from the ECM, i.e.
there is a loss of normal cell-matrix interactions, they may undergo anoikis.
However, metastatic tumor cells may escape from anoikis and invade other
organs.” (“Anoikis,” Wikipedia on the
web)
(Note: This may sound contradictory as you read, so
keep in mind that I am writing of “relatively” different amounts of DHEA. Even
if DHEA is “low,” the relative amount of DHEA a cell may absorb may actually be
“increased” when a cell's surface is increased.)
It
is my hypothesis that evolution selected DHEA because it optimizes replication
and transcription of DNA. Therefore DHEA
levels positively affect all tissues, including cancer. Basically, I suggest cell surface access to
DHEA determines whether a cell simply divides or enters into differentiation
and becomes part of a tissue. That is,
as tissues form, the amount of available DHEA determines the amount of DNA
activity. A large amount of DHEA can
stimulate the genes which control mitosis while reduced DHEA activates less
DHEA activity. The amount would change
as the cell becomes part of a tissue matrix which would reduce the cell surface
area necessary to absorb DHEA. As
tissues develop, cell adhesions increase which reduce cell surface area. These adhesions would be characteristic of
the differentiated state of the tissue level.
It follows that as the embryo develops and grows, different genes would
be activated sequentially because of this mechanism.
I
think low DHEA triggers
cancer oncogenes.
DHEA naturally begins to decline around the ages of twenty to
twenty-five, reaching very low levels in old age. Most cancers develop in old age; I think it
is because of low DHEA. As DHEA
declines, the ability to maintain tissues also declines. This reduces the cell adhesions within the
tissues and exposes some cells to the extra cellular milieu. This exposes some cells to increased DHEA
availability, that is, their cell surfaces increase and they absorb a
“relatively” increased amount of DHEA compared to that required to maintain the
differentiated state. If the cell
contains oncogenes, that is, genes which are turned on by extra DHEA
inappropriately, then they begin to divide and cancer is initiated. (Early on in our development, our very early
cells exhibit increased free surface areas so mitosis occurs more than
differentiation; the ratio is changed as tissues develop.)
If
DHEA declines and cell adhesions decline, then a cell's surface area may
increase. If the cell contains oncogenes
which start mitosis, the extra absorbed DHEA would drive mitosis; cancer in
situ would form. If, in some of the
cells, cell adhesions are reduced significantly to the point that the cell is
released, then the cancer would metastases.
Metastatic cells avoid the “programmed cell death” of anoikis because
they are able to duplicate. If the
released cells do not start mitosis, then they are simply free differentiated
cells and cannot survive because they do not duplicate, and they appear to
exhibit “programmed cell death.”
(Note:
All cells compete for available DHEA.
This competition is part of our developmental pattern; for example, I
think the human brain takes DHEA at the expense of the body. This is why our brains are big but our bodies
are smaller compared to other
primates.
Since
cancer cells exhibit increased surface areas, cancer can absorb DHEA at the
expense of other tissues. I suggest this
is how cancer causes cachexia, the decline of the body during cancer and is
especially increased in the elderly who are not producing DHEA in large
amounts.)