Dr. Norman Nevin from the Queen's University of
Belfast has announced that for the first
me, gene therapy has been used to cure a woman who
was dying of ovarian
cancer. The
treatmenttook place some four years ago at the Royal
Marsden Hospital in London but it has
taken until now to determine that the woman was successfully
cured as the cancer has not returned.
In the study, the scientists modified a simple cold virus to
carry human genetic material. The cance-rous cells were then
infected with the virus. Amazingly, the modified virus was able
to stop the can-cer cells from continuing to multiply. Thousands
of women develop ovarian cancer each year and a significant
number of these women die from the disease. The tumors typically
develop "obscurely" and are difficult to detect until
they have reached a critical size. This treatment raises hope
as ovarian cancer is one of the most difficult forms of cancer
to treat. Generally speaking, a person who is alive four years
after the last incidence of ovarian cancer is considered cured,
hence the long duration between the treatment and the announcement
of success by the researchers.
Adenovirus, a mild pathogen that can cause
a cold, similar to the virus used in the study. Image courtesy
of Linda M. Stannard, University of Cape Town.
This was the first successful use of gene therapy to cure a
person of cancer. The researchers hope that it will soon be
tested and applied to other forms of cancer. Current trials
for a very similar gene therapy technique are underway at the
University of Kentucky and at the University of Texas Southwestern
Medical Center. What do you think? How close do you think this
puts us to finding a cure for all forms of cancer? Do you think
that the techniques used will be applicable to other forms of
cancer? Come on over to the Biology Forum and share your thoughts,
opinions and feelings. Till next time...
Genetically-Engineered Adenovirus
That Kills Cancer Cells
Introduction
This article is about something really exciting that may offer
hope for our ability to specifically target certain cancer cells,
and kill them - without harm to our normal cells. You have probably
read in the newspaper or heard on various news broadcasts recently,
about a virus which has been purposefully genetically altered
for use in treating cancer patients. And, you may have
heard that certain clinical trials have been started to examine
this virus for possible use as a therapy for cancer patients.The
present article is based upon recent research published in the
October 18, 1996 issue of the scientific journal Science. TheScience
article is:
Bischoff, J.R., D.H. Kirn, A. Williams, C. Heise, S. Horn,
M. Muna, L. Ng, J. Nye, A. Sampson-Johannes, A. Fattaey, and,
F. McCormick. 1996. An Adenovirus Mutant That Replicates Selectively
in p53-Deficient Human Tumor Cells. Science 274: 373-376
All of these scientists listed are or were associated with
ONYX Pharmaceuticals, 3031 Research Drive, Richmond, California94806.
The Science article is pretty technical, so, I thought you might
wish to know what is going on here in a bit less technicallanguage....
why this particular approach has been taken, and why this approach
offers some hope for future therapeutic approaches. To explain
this information, we need to examine some background, and then
we'll talk about specifics. I must tell you that I am going
to leave out certain precise things - and, I will not be absolutely,
scientifically accurate in my explanations. However, I won't
take too much latitude with my explanations. So, I hope the
information I give may help you to understand this system a
little better.
Our Cells and Cell Division
Except for certain skin cells, cells which appear from our bone
marrow, and certain immune system cells, most normal human cells
are usually quiescent, e.g., not dividing. And, even when certain
of our cells are specifically triggered to divide when they
are supposed to divide (like our activated immune system cells
which help us to fight infections, etc.,) the number of cell
divisions "allowed" is usually pre-programmed, and
limited. Our cells have thus evolved in such a way that results
in a system which essentially protects the body from any cell
which no longer has cell division under strict regulatory control
- the loss of such regulation is of course the condition we
call, cancer. If a single one of the over 65 trillion cells
in the human body loses
the ability to regulate cell division, this loss of regulation
can of course eventually lead to the formation of a tumor, or
many, many cells which do not necessarily aggregate but disperse
throughout the body.
What is the Cell Division Regulatory
System?
Fortunately for us, there is a suppressor system within each
of the over 65 trillion (over 200 different types) of cells
within our body. One of the major components of this division
suppression system is the protein known as p53 (protein of 53,000
molecular weight). A certain amount of functional p53 must be
available within each of these cells to maintain this condition
of cell division suppression. In the presence of p53, a cell
will enter what is known as G0 or will enter what is known as
G1 arrest at the appropriate time.
