By Stephen Ornes
The Molecules That Make Your Cancer Your Own
The proteins in a patient’s cancer cells may hold the key to personalized treatment
By Stephen Ornes
For cancer patients, the disease and its treatment are nothing if not personal. But to cancer researchers, the idea of “personalized medicine” means something a little different, even something hopeful: The premise that in the future, rather than treating a person’s type of cancer, doctors will be able to precisely tailor a patient’s therapy to match his or her particular tumor. Personalized medicine is built on the idea—reinforced by study after study—that cancer isn’t just one disease, as was long believed.
This means that there will probably never be one single cure for cancer. Instead, what researchers now believe is that there will come a time when we treat cancers by assessing and then disrupting the biochemical processes that make a specific tumor lethal. This could mean that one day a man diagnosed with prostate cancer may learn that he needs no treatment and can live with the disease worry free for the rest of his life, while his neighbor may be advised that he has an early but aggressive prostate cancer that requires prompt treatment with a specific drug, and that he will be monitored, in real time, so that his oncologist can see how well the tumor responds to therapy and modify the dosage as needed.
The key to diagnosing, treating and monitoring cancer this precisely hinges on understanding how proteins operate. Proteins are the blue-collar workers deep inside the body. Molecules that construct, maintain and repair cells, proteins provide structure, act as enzymes and hormones, and transport important cargo like oxygen. They also regulate genes and act as antibodies that fight against disease. In essence, proteins are the builders of the body’s cells, which means they’re also the builders of cancer—a role that makes them natural targets for research. Encompassing this research is the field of science called proteomics: the large-scale study of all the protein molecules in a cell—their interactions, their activity, their jobs, their shapes.
Proteins & Prognosis
When the prostate-specific antigen (PSA) test was first introduced in 1986, researchers were hopeful that it would reduce prostate cancer deaths. But it’s now clear that while the test can indeed find lethal cancers, it is also detecting slow-growing tumors that will never harm the patient—or even conditions like prostatitis that have no proven link to cancer.
“It’s very difficult to identify the patients early on who have aggressive cancers and those who do not,” says Richard Caprioli, a proteomics researcher at Vanderbilt University in Nashville, Tenn.
Distinguishing among subtypes of cancers—whether among kinds of prostate cancers or breast cancers or lung cancers—is something of a holy grail for cancer researchers. And proteins play a starring role in these efforts: As tumors grow, they release certain kinds of proteins into bodily fluids like blood, urine or saliva. Like molecular dispatches from the tumor, these proteins convey identifying information about the disease.
Caprioli, for one, wants to find a way to understand that information. He is developing a technology—a new version of mass spectrometry (see the sidebar "Tools of the Trade")—that might help researchers distinguish among outwardly similar tumors based on protein patterns. Caprioli hopes that his tool will be able to find and decode the protein patterns associated with different types of tumors—giving doctors information about a tumor’s size or aggressiveness that could be used to drive treatment decisions.
(photo: © James King-Holmes / Photo Researchers Inc.)