Tracking Proteins in Cancer Cells

In a paper published in the Journal of the American Medical Association, scientists at the National Cancer Institute (NCI) and the Food and Drug Administration have reported on advances in a new and extremely promising field of cancer research-proteomics.

Proteomics involves the study of proteins in living cells, in this case focusing on how proteins in cancer cells differ from those in normal cells, and how they will respond to different cancer treatments.

"This program is the only one in the world where we can monitor the protein status of a patient before, during, and after treatment for cancer," said J. Carl Barrett, Ph.D., director of NCI's Center for Cancer Research.

"The great challenge now in proteomics research is to begin to apply these technologies to clinical care," added co-author Emanuel Petricoin, Ph.D., of the FDA's Center for Biologics Evaluation and Research. "We hope to take these techniques out of the lab to assess their benefit for people with cancer, in a true bench-to-bedside clinical research program."

The specific goal of proteomics research is to characterize the information flow within the cancer cell. The researchers hope to generate "protein fingerprints" that may provide early indications of a drug's effectiveness and side effects before it is given to an individual patient.

The potential benefits of their clinical proteomics research include:

• Developing individualized therapies that have been predetermined to be effective for each patient;
• Determining the toxic and beneficial effects of treatments in the lab before using them in patients;
• Diagnosing cancer earlier than is now possible; and,
• Improving the understanding of tumors at the protein level, leading to better treatments.

The researchers have already identified more than 140 proteins in cancer cells tissues of the breast, ovary, prostate, and esophagus that change in amount as the cells in these tissues grow abnormally.

Furthermore, they have been able to take biopsied cells from cancer patients before and after treatment using a special Laser Capture Microdissection Microscope. The microscope allows them to isolate pure normal cells, pre-cancerous cells, and tumor cells from the same patient. By capturing cells directly from the tissue, the original protein pattern of the cells is maintained, which is not the case with traditional methods of isolating cells.

They then analyze the patterns of proteins in the extracted tumor cells after the patient has been treated. The researchers are trying to determine how a particular treatment changes the network or circuitry of the proteins in a cell, and whether the protein patterns change if the tumor returns after treatment.

SOURCES:
Journal of the American Medical Association, November 14, 2001; 286:18
National Cancer Institute (http://www.nci.nih.gov)

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