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Researchers have been investigating how to control the transcriptional activation of gene expression in cancer. Identifying how a transcription factor binds, or a pathway that activates where a gene can be turned off, has led to new drugs and new ways to treat cancer. In breast cancer, for example, many proteins are overexpressed. This can lead to increased phosphorylation of key transcription factors that increase transcription. One such example is the overexpression of the epidermal growth factor receptor (EGFR) in a subset of breast cancers. The EGFR pathway activates many protein kinases that, in turn, activate many transcription factors that control genes involved in cell growth. New drugs that prevent the activation of EGFR have been developed and are used to treat these cancers.

Cancer and post-transcriptional control

Changes in the post-transcriptional control of a gene can also result in cancer. Recently, several groups of researchers have shown that specific cancers have altered expression of miRNAs. Because miRNAs bind to the 3' UTR of RNA molecules to degrade them, overexpression of these miRNAs could be detrimental to normal cellular activity. Too many miRNAs could dramatically decrease the RNA population leading to a decrease in protein expression. Several studies have demonstrated a change in the miRNA population in specific cancer types. It appears that the subset of miRNAs expressed in breast cancer cells is quite different from the subset expressed in lung cancer cells or even from normal breast cells. This suggests that alterations in miRNA activity can contribute to the growth of breast cancer cells. These types of studies also suggest that if some miRNAs are specifically expressed only in cancer cells, they could be potential drug targets. It would, therefore, be conceivable that new drugs that turn off miRNA expression in cancer could be an effective method to treat cancer.

Cancer and translational/post-translational control

There are many examples of how translational or post-translational modifications of proteins arise in cancer. Modifications are found in cancer cells from the increased translation of a protein to changes in protein phosphorylation to alternative splice variants of a protein. An example of how the expression of an alternative form of a protein can have dramatically different outcomes is seen in colon cancer cells. The c-Flip protein, a protein involved in mediating the cell death pathway, comes in two forms: long (c-FLIPL) and short (c-FLIPS). Both forms appear to be involved in initiating controlled cell death mechanisms in normal cells. However, in colon cancer cells, expression of the long form results in increased cell growth instead of cell death. Clearly, the expression of the wrong protein dramatically alters cell function and contributes to the development of cancer.

New drugs to combat cancer: targeted therapies

Scientists are using what is known about the regulation of gene expression in disease states, including cancer, to develop new ways to treat and prevent disease development. Many scientists are designing drugs on the basis of the gene expression patterns within individual tumors. This idea, that therapy and medicines can be tailored to an individual, has given rise to the field of personalized medicine. With an increased understanding of gene regulation and gene function, medicines can be designed to specifically target diseased cells without harming healthy cells. Some new medicines, called targeted therapies, have exploited the overexpression of a specific protein or the mutation of a gene to develop a new medication to treat disease. One such example is the use of anti-EGF receptor medications to treat the subset of breast cancer tumors that have very high levels of the EGF protein. Undoubtedly, more targeted therapies will be developed as scientists learn more about how gene expression changes can cause cancer.

Career connection

Clinical trial coordinator

A clinical trial coordinator is the person managing the proceedings of the clinical trial. This job includes coordinating patient schedules and appointments, maintaining detailed notes, building the database to track patients (especially for long-term follow-up studies), ensuring proper documentation has been acquired and accepted, and working with the nurses and doctors to facilitate the trial and publication of the results. A clinical trial coordinator may have a science background, like a nursing degree, or other certification. People who have worked in science labs or in clinical offices are also qualified to become a clinical trial coordinator. These jobs are generally in hospitals; however, some clinics and doctor’s offices also conduct clinical trials and may hire a coordinator.

Section summary

Cancer can be described as a disease of altered gene expression. Changes at every level of eukaryotic gene expression can be detected in some form of cancer at some point in time. In order to understand how changes to gene expression can cause cancer, it is critical to understand how each stage of gene regulation works in normal cells. By understanding the mechanisms of control in normal, non-diseased cells, it will be easier for scientists to understand what goes wrong in disease states including complex ones like cancer.

Questions & Answers

what is abiotic and biotic factors?
Hira Reply
which of the following shows the correct sequence of the cell cycle
Kameishia Reply
who is name virus
Shivam Reply
centromere consist of
Shivam
meeting point of two chromatids
Cffrrcvccgg
Explain the function of nematocysts in cnidarians?
Israel Reply
The nemotocyst is used by Cnidarians (hydra, jellyfish, sea anemones) to sting their prey and any threatening enemy.
Lee
photosynthesis in plants is an example of what ? (a) excretion (b) irritability (c) nutrition (d) reproduction
Lee Reply
If a Hox 13 gene in a mouse was replaced with a Hox 1 gene, how might this alter animal development?
Israel Reply
Which of the following organisms is most likely to be a diploblast?
Israel
what are reactions of photosynthesis?
Maria Reply
what are the probabilities of blood genotypes for the offspring from a cross between a mother lAlA blood and a father with lBi blood?
dayana Reply
what is matter
Emmanuel Reply
matter is anything that has mass and can occupied space
Alice
weight
Alice
example of matter
Oyekemi
You serves as an example of matter Because matter is anything that has mass and occupy space e.g man and every other things that exist on earth.. So think of every other things around you ...
Biola
and you too
Oyekemi
We generally
Biola
What is ecological management
Oyekemi
how the kidney functions as osmoregulatory organ
Sam Reply
That true
Banda
what is the major connection for sugars in glycolysis?
Ibrahim Reply
Simple term of science
Palesa Reply
what does it mean
gopal
it's means what do u know about biology?
Phathu
what is immunisation
Melysa
the action of making a person immune to infections ,for immunisation
Kalia
what is the biology? what do you know about biology
Phathu Reply
biology is the study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution.
Julia
The study of all aspects of life. The study of all living organisms (such as animal cells and plant cells) in greater detail (their structure and how they function). It's a very broad science.
juanita
what is prokaryotic
Bhaskar Reply
what is pathogens
Bhaskar
pathogens are a bacterium, virus, or other microorganism that can cause disease.
Lee
transistion metals....
Wasik Reply

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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