Cancer cells divide out of contol side effects of chemotherapy and
radition therapy that fight cancers include loss of hair and of the
gastrointestinal lining, producing severe nausea. Note that cells in
hair follicles and intestinal lining divide frequently. What can you
infer about the mechanisms of these treatments? What would you look
for in an improved cancer therapy?

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Request for Question Clarification by pafalafa-ga on 08 May 2004 18:51 PDT

Hello pat53-ga,

Many of the main chemotherapy agents work principally by inhibiting
cell division.  Since cancer cells divide so rapidly, they are
susceptible to these drugs, but - unfortunately -- so are other cells
that actively divide, such as follicle cells and gastrointestinal
cells.  The thrust of a lot of current research to improve
chemotherapy is to find or design drugs that will specifically target
cancer cells, without affecting non-cancerous healthy cells.

What sort of details would you like a researcher to provide in order
to provide you a full answer to your question?  Your subject asks "How
cells reproduce"..is that the question you want us to focus on...?

Let us know, and perhaps we can assist you.

pafalafa-ga

pafalafa-ga

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Clarification of Question by pat53-ga on 08 May 2004 19:36 PDT

What can you infer about the mechanisms of these treatment? What would
you look for in improved cancer therapy?

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Request for Question Clarification by pafalafa-ga on 08 May 2004 20:19 PDT

I would infer that the current treatments target cell-division in all
cell types, whether cancer cells or normal healthy cells.

I would look for improved therapies that distinguish cancer-cells from
non-cancer cells, and only target the cancer cells.

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Clarification of Question by pat53-ga on 09 May 2004 19:07 PDT

I want to take the subject to Cancer cells dividing out of
control,because of the chemotherapy and the radition. \Note that the
cells in hair follicles and intestinal lining is dividing frequently.
What is causing it? And what can you onfer about the mechanisms of
these treatments (chemotherapy and radiation)? What would you look for
in an improving cancer therapy?

Chemotherapy and Radiation therapy both target rapidly dividing cells,
as has been amply discussed.  With regards to your last clarification,
cancer cells aren't growing out of control because of the chemo and
radiation (although, interestingly, these are the same agents that can
cause cancer) they are dividing out of control because of defects
typically in cell-division-cycle genes, or in the various
cell-division-cycle checkpoints.  Hair follicles and intestinal lining
recieve growth signals, or mitogens, that specifically cause them to
rapidly divide.  This is a normal process; and is necessary, as these
tissues are subject to lots of trauma and need to be replaced often. 
The mechanism of chemotherapy and radiation, based on the fact that
they interfere with rapidly dividing cells, we can infer, is that they
interefere in someway with the cell-cycle.  This could include
preventing DNA replication, preventing transciptional or translation
of certain proteins.  Improvements in cancer therapy are moving away
from the traditional treatments, and towards a process called
angiogenesis.  Angiogenesis is the process by which new blood vessels
are formed.  In order for a tumor to survive, it must be able to
recruit ample blood supply.  Anti-angiogenesis drugs would prevent
thet formation of these blood vessels, in effect they would starve a
tumor to death.  Other treatments include looking for cell-surface
markers that distinguish cancer cells from non-cancer cells, and drugs
that can send a cell down the pathway to cell death, called apoptosis.