Wednesday, 21 March 2012

Gene expression profiling to revolutionise cancer diagnosis and treatment




Gene expression profiling to revolutionise cancer diagnosis and treatment
Christie Younger 42898739

The onset of cancer can be sudden. We like think that "it won't happen to us" but the thing is, we have a 1 in 2 chance of developing cancer in our life time (National Cancer Institute 2011). The worst part is that we can't predict it or prevent it. Plus, it can be difficult to diagnose cancer in its early stages as seen in how basal cell carcinomas, a common type of skin cancer, can become widely spread before clinical signs occur (Tomas 2009). The good thing is advancements in cancer research. Scientists are currently undergoing research to identify genes that, when expressed, cause the development of cancer (University of Utah, 2012a). The procedure they use is called gene expression profiling. This procedure is widely used in cancer research as scientists across the globe try to understand cancer and discover ways to try and predict, diagnose and treat it.

Figure 1.0 A microarray slide. 
(University of Utah 2012b)
Gene expression profiling is a procedure that aims to identify genes that are activated and record why they are activated (University of Utah 2012a). By cataloging the genes and their purpose, scientists aim to find genes that when triggered contribute to the development of cancer and other diseases. The technique used to determine whether or not a gene is activated is called microarray analysis.




Figure 2.0 A microarray scanner (University of Utah, 2012b)
Microarray analysis is a technique used to determine if a gene is activated or not (University of Utah 2012b). This is done collecting a sample of the same cell type from different individuals of an organism (University of Utah 2012b). From these samples, the mRNA is extracted from DNA as the presence of mRNA indicates an activated gene (University of Utah 2012b). From here, the mRNA is used to create DNA copies of the activated genes (University of Utah 2012b). These copies are then placed on a microarray, which is similar to a microscope slide (University of Utah 2012b). The microarray is then placed in a microarray scanner and the scanner will then search for all similarities and differences between the activated genes (University of Utah 2012b). Similarities and differences are shown by coloured dots: same coloured dots means the same gene is expressed, different coloured dots means different genes are expressed (University of Utah 2012b). Microarray analysis allows for large numbers of genes to be processed at once, which makes it quite effective technique to use (University of Utah 2012b).

Figure 3.0 List of activated genes (University of Utah 2012a).
In the real world, gene profiles from a patient with cancer can be compared to a person without cancer to see if there is a gene or a combination of genes that, when activated, contribute to the development of cancer. In the journal article 'Gathering insights on disease ... from gene expression profiles of healthy tissues', which was only published last December, researchers from the University of Liverpool used gene expression profiling to identify a number of genes that held a connection with cancer incidence (Berres et all. 2011). These genes were involved in ribosomal and transcriptional activity, along with translation and protein synthesis (Berres et all. 2011). They also found that organs that were less likely to develop cancer had low levels of suspected cancer related genes than organs that were more likely to be cancerous (Berres et all. 2011). Through gene expression profiling, the patient’s genes can be compared to the genes that indicate cancer to check if the patient has a genetic disposition to have cancer (University of Utah 2012a).

Through research, scientists are gaining a deeper understanding of cancer through using techniques such as genetic expression profiles. Genetic expression profiles are revolutionising the way cancer is diagnosed and even allows for the probability of cancer incidence to be predicted by checking if a patient has cancer-associated genes.  

Bibliography
Books
  Berres, S, van Dam, S, de Magalhaes, JP,  McArdle, A, Silva, AS,  and Wood, SH, 2011, Gathering insights on disease etiology from gene expression profiles of healthy tissues. Oxford University Press. Oxford.

Websites
  National Cancer Institute 2011, Lifetime Risk (Percent) of being Diagnosed with Cancer by Site and Race/ Ethnicity, viewed 18 March 2012, < seer.cancer.gov/csr/1975_2008/results_merged/topic_lifetime_risk_diagnosis.pdf >
  Tomas, S 2009, Difficult to diagnose skin cancer, viewed 18 March 2012, < www.racgp.org.au/afp/200907/200907tomas.pdf >
  University of Utah 2012a, Gene Expression, viewed 18 March 2012 < http://learn.genetics.utah.edu/content/labs/microarray/expression/ >
University of Utah 2012b, Profiling Technique: Microarray Analysis, viewed 18 March 2012 < http://learn.genetics.utah.edu/content/labs/microarray/analysis/ >

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