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Discovering Various Gene Expressions
Gene expression means whether or not a gene (part of the patient's tumor cell's DNA) is expressed, meaning its RNA being made from the gene (RNA is the intermediary which codes for protein synthesis and it is the activity of proteins which determine the behavior of a tumor cell).
In chemotherapy selection, gene and protein analysis examines a single process within the cell or a relatively small number of porcesses. The "aim" of gene and protein expression testing is to tell if there is a theoretical predisposition to drug reponse. The goal is to look for patterns of normal and abnormal gene expression which could "suggest" that certain proteins might or might not be produced within a cell. Just because a gene is present, it does not mean that an associated protein has been produced.
Protein testing goes one step further by testing to see if the relevant protein actually has been produced. However, even protein testing cannot tell us if a protein is "functional" or how it will interact with other proteins in the presence of targeted anti-cancer drugs. Functional Tumor Cell Profiling tests not only for the presence of genes and proteins but also for their "functionality," for their interaction with other genes, proteins and processes occurring within the cell, and for their response to targeted anti-cancer drugs.
Gene and protein analysis cannot discriminate among the activities of different drugs within the same class. Instead, gene and protein examination assumes that all drugs within a class will produce precisely the same effect, even though from clinical experience, this is not the case. Nor can gene and protein tesing tell us anything about drug combinations. Functional Tumor Cell Profiling measures genes before and after drug exposure. Gene Expression Profiles measure the gene expression only in the "resting" state, prior to drug exposure.
Given the technical and conceptual advantages of Functional Profiling Assays together with their performance and the modest efficacy of therapy prediction based on analysis of genome express, there is reason for a renewal in its interest for optimized use of medical treatment of malignant disease. The assay can actually integrate all the gene expression into one convenient test result.
It's not an either/or situation. Cancer is a complex disease and needs to be attacked on many fronts. The best thing to do is to combine these and other different tests (protein function, cell function and disease analysis) in ways which make the most sense.
Reference: Cell Function Analysis
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