CISN - Molecular Diagnostics

Overview

Traditional clinical diagnostic assays monitor the chemical and cellular biomarkers of diseases in the blood or other body fluids. These are the tests we all receive when we go in for our annual medical exam - liver enzymes, cholesterol, etc.

This began to change in 1985 with advances in gene amplification technologies and bioinformatics resulting from the Human Genome Project. Based on the data generated through this multi-nation project scientists now believe the human genome holds approximately 23,000 genes directing the blueprints of more than 100,000 proteins.

Industry analysts estimate that if just 5% of these genes and proteins have diagnostic significance, 1,500 gene and 5,000 protein based-tests could be marketed commercially. A portion of these will be cancer specific.

Cancer molecular diagnostics involves the measurement of DNA, RNA, proteins, or metabolites to detect a person's genetic makeup. Any changes in the DNA of a cell, or changes in chemical processes associated with it, may soon be used to determine the presence of cancer. Specifically, molecular diagnostics incorporates genomics and proteomics to evaluate expression patterns of genes and proteins.

Background: The importance of cell communication

Crucial for all normal cell growth is a communications network that functions properly. This network is an intricate collection of pathways built with interactive proteins. The genetic changes involved in cancer result in alterations in the proteins that disrupt the cell's communication network.

Image courtesy of the National Cancer Institute

As cancer develops, altered proteins along many different pathways cause signals to be garbled, intercepted, amplified, or misdirected. These changes hijack what was once normal communication and use it to achieve uncontrolled tumor growth.

Don't worry about the many small pathways shown in the image above - just remember that cancer disrupts these pathways and the resulting proteins can be found and measured using molecular diagnostics.

Molecular diagnostic use

In the field of cancer diagnostics, it is hoped that early detection using screening programs with highly sensitive and extremely specific cancer diagnostic protocols will translate to accurate and appropriately targeted therapy selection.

While the incidence of cancer and the deaths due to cancer still remain high, novel cancer molecular diagnostics (CMD) are allowing physicians and pathologists to more accurately diagnose cancers, identify predisposition, and select targeted and individualized therapeutic regimens (targeted therapy and biomarkers).

While the traditional pathological examination of cancer remains an essential clinical tool, newer technologies such as microarrays, real time PCR (RT-PCR, - process of DNA amplification and quantification), mass spectrometric proteomic analyses, and protein chips are moving to center stage, although not yet routinely used by all or in all cancer types.