Weakened RNA interference reduces survival in ovarian cancer

Dec 18, 2008 | Posted by: roboblogger | Full story: Physics Org

Levels of two proteins in a woman's ovarian cancer are strongly associated with her likelihood of survival, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reports in ...

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1 - 12 of 12 Comments Last updated Jan 13, 2009

Since: Dec 05

Union, NJ

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#1
Dec 22, 2008
 
Microarrays (gene chips) examine what genes are expressed in cancer cells. It is mainly used for screening/gene discovery work. You screen 50,000 genes to discover an association and then you focus in on only a few hundred or so for more careful study by some other method like real time polymerase chain reaction (RT-PCR).

Genes make proteins, the molecules that comprise and maintain all the body's tissues. Genes produce their effect by sending molecules called messenger RNA to the protein-making machinery of a cell. They set the protein-making machinery in motion through a "gofer" messenger called RNA (or mRNA).

The technique called RNA interference (RNA-i) allows scientists to "silence" certain genes. In RNA interference, certain molecules trigger the destruction of RNA from a particular gene, so that no protein is produced. Thus, the gene is effectively silenced. RNA interference is already being widely used in basic science as a method to study the function of genes and it is being studied as a treatment for cancer.

This RNA interference occurs naturally in plants, animals, and humans. RNA interference is important for regulating the activity of genes (a fundamental mechanism for controlling the flow of genetic information). RNA interference (RNAi) interferes with mRNA, a natural molecular switch, regulating gene expression in plants, animals and humans, by "silencing" over-active or malfunctioning genes.

The ability to introduce foreign DNA into cultured cells with DNA gene sequences has allowed us to assign functions to different genes and understand the mechanisms that activate or redress their function. It has made gene therapy research possible, like with the proteins Dicer and Drosha.

However, giving instructions on the genetic differences that determine how a person responds to a drug will still have cancer medicine being prescribed on a "trial-and-error" basis, with adverse drug reactions remaining a major cause of injury and hospitalizations.

All the gene mutation or amplification studies can tell us is whether or not the cells are potentially susceptible to this mechanism of attack. The don't tell you if one drug is better or worse than some other drug which may target this.

The cell is a system, an intergrated, interacting network of genes, proteins and other cellular constituents that produce functions. You need to analyze the systems' response to drug treatments, before you find clinical responders.

Genetic profiles cannot discriminate differing levels of anti-tumor activity occurring among different targeted therapy drugs. Nor can they identify situations in which it advantageous to combine a targeted drug with other types of conventional cancer drugs.

Two years ago, three federal agencies, NCI, FDA, and CMS, announced a program to try to identify biological indicators, or biomarkers, which may indicate whether a cancer patient is likely to benefit from a given anti-cancer therapy, or even whether they will suffer from certain side effects.

We have the biomarkers for who will respond so we don't give these powerful and expensive medicines to those who won't. Technologies, developed over the last twenty years by private researchers, hold the key to solving some of the problems confronting a healthcare system that is seeking ways to best allocate available resources while accomplishing the critical task of matching individual patients with the treatments most likely to benefit them.
Gail Perry

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#2
Dec 22, 2008
 
"
Genetic profiles cannot discriminate differing levels of anti-tumor activity occurring among different targeted therapy drugs."

Not YET.

We do not have all the needed biomarkers. New ones are being found literally every day. In addition, tumors change their response over time. Once a tumor has been removed, the stray cells that remain can be quite tough, find places to hide and spring into action as long as 15 year later, and at that point cures are extremely rare.

The health care system is not at fault here. There are literally thousands of different kinds of cancers. It isn't just one disease, and they're researching as fast as they can. If the tests you imagined actually existed, someone somewhere would be using them if for no other reason than that they would be highly profitable.

You have kludged together things you have read selectively and over-interpreted in order to draw the conclusions you want. If this is not true, properly footnote your claims so those of us who like to verify what we read can do so.

Since: Dec 05

Union, NJ

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#3
Dec 26, 2008
 
The era of personalized medicine based on validated biomarkers is indeed at hand. As the increasing numbers and types of cancer drugs are developed, oncologists become more and more likely to misuse them in their practice. Developing a good and clinically practical drug selection system is no less important than the discovery of new drugs or how to put them into the body.
Gail Perry

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#4
Dec 26, 2008
 
Yes, gdp. My care was QUITE personalized. however, the test you keep ranting about is still in development.

I think you have a financial interest in these tests. I think you've invested in them ... or are being paid to post about them.

Since: Dec 05

Union, NJ

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#5
Dec 27, 2008
 
Why is it that you make up stories Gail?
Gail Perry

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#6
Dec 27, 2008
 
I think you have a financial interest in these tests, gdp. Either you have invested in them or you are being paid to post.

Since: Dec 05

Union, NJ

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#7
Dec 31, 2008
 
I would appreciate you stop lying Gail. Please seek help.
Gail Perry

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#8
Dec 31, 2008
 
gdp I think you have a financial interest in these tests. Either that or you are being paid to post. That's not a lie (learn some English) because I stated that it was my opinion.

Since: Dec 05

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#9
Jan 7, 2009
 
Remember, all the gene amplification studies can tell us is whether or not the cells are potentially susceptible to a pathway or mechanism of attack (Dicer and/or Drosha). They don't tell you if one drug is better or worse than another drug which may target these.

Assessing gene expression is important in order to identify new therapeutic targets and thereby to develop useful new drugs. However, it is still years away from working successfully in predicting treatment reponse for individual patients.

The signaling pathways in solid tumors are very complex and many. Cancer cells can use any of dozens of biochemical pathways to proliferate and spread. Stop one or two pathways and the cells can turn on a different pathway.

The challenge is to figure out which patients to give new targeted drugs to. Targeted therapies are typically not very effective when used singularly or even in combination with conventional chemotherapies. The targets are so narrow that cancer cells are likely to eventually find ways to bypass them.

We do have effective cell-based profiling methods, which exist today and is not hampered by the problems associated with gene expression tests. It measures the net effect of everything which goes on (the entire genome of a cancer cell).

They analyze the systems' response to drug treatments, not just one or a few targets or pathways, not just Dicer and Drosha.
Gail Perry

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#10
Jan 8, 2009
 
"Remember, all the gene amplification studies can tell us is whether or not the cells are potentially susceptible to a pathway or mechanism of attack (Dicer and/or Drosha). They don't tell you if one drug is better or worse than another drug which may target these."

And, they can't, because cancer cells are highly sensiitive to their environment, and that can't be tested in a test tude.

Gene amplification studies are only useful for research and for finding two specific genes. They don't have one for the one they JUST found that allows cancer cells to grow and spread. Gene replication studies can't tell us how cancer cells will die *in our bodies* because ... they aren't in bodies when they're in a lab.

Folks, gdp is telling us science fiction -- in other words, POSSIBLE science of the future -- not some treatment that is available now. He keeps insisting that they can take our cells, test them, and determine with precision what chemotherapy we will respond to.

Go to your oncologist and ask. You'll find we're not to that point yet.

A lot of this research is extremely promising, but there have been a lot of promising approaches in the past that didn't pan out in real life with real people.

I really think gdp must have some financial interest in all this -- either heavily investing in the companies doing this research, or being paid to post about them. This technology does not yet exist. PLEASE, folks, if you're facing cancer, talk to your oncologist. Get a second opinion, but don't rely on things you read on line from strangers (that includes websites as well as blogs). The way to effectively fight breast cancer is to catch it early and throw everything that is appropriate at it. Give yourself the best possible chance from the very beginning to keep it from spreading.

Since: Dec 05

Union, NJ

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#11
Jan 12, 2009
 
Gail, your paranoia is only exceeded by your ignorance.
Gail Perry

United States

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#12
Jan 13, 2009
 
I used every tool available for my type of breast cancer. Now it's 27 months later and there is absolutely no sign of its return.

That could change tomorrow, but if it does, I will at least know I did everything I could to prevent it.

That is the course of action I suggest for people faced with breast cancer: face it square on. Deal with it, and then ... get on with life. A hundred other things could kill me before breast cancer does even if it does eventually return. The gift was the knowledge of how important every day truly is.

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