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Inside job: new radioactive agents for colon cancer work inside cells
October 10, 2007Johns Hopkins scientists have developed a potentially novel way to fight colorectal cancer using tiny molecules to deliver potent barrages of radiation inside cancer cells, unlike current treatments that bind to the surface of cells and attack from the outside and cause unwanted side effects.
In laboratory studies with normal and cancer cells, the new radiation delivery system proved able to specifically target colon cancer cells, and what's left over is likely to be easily filtered out by the kidneys because the delivery system's molecules are so small.
As reported online in PLoS One on October 3, Hopkins colorectal cancer specialists John Abraham, Ph.D., and Stephen Meltzer, M.D. -working with the notion that small molecules generally make better treatment packages-designed small bits of protein only 10 amino acids long as the foundation for their drugs. By contrast, antibodies used to deliver radiation or chemicals can be over one thousand amino acids long.
The team attached radioactive phosphorous, P32, as a test of how well their peptides worked and "to our surprise, our first tests showed that cells were ingesting these molecules, thus transferring the radiation inside and killing them by breaking up their DNA and proteins," Abraham says.
While cautioning that the new radiation delivery system is still far from ready for use in people, Abraham notes that P32 gives off high energy that can penetrate through 5 millimeters of human tissue, making it a good candidate to tackle colon cancer since colon cancer cells can often form large, thick tumors into which drugs may not penetrate very well. In addition, P32-labeled peptides may serve another valuable use: to find small metastases or recurrences of colon tumors while they are still small enough to treat. Images of the body can be taken of the labeled peptides as they bind, revealing where stray tumor cells may be nesting.
Abraham, Meltzer and their team then designed and tested a variety of P32-peptides on 18 normal and cancerous human cell samples. The most potent peptide, MA5, could bind to adenocarcinoma cells, which make up 95 percent of all colon cancers, 150 times more strongly than other cell types and be transferred inside cells within 2 hours.
Johns Hopkins Medical Institutions
The team attached radioactive phosphorous, P32, as a test of how well their peptides worked and "to our surprise, our first tests showed that cells were ingesting these molecules, thus transferring the radiation inside and killing them by breaking up their DNA and proteins," Abraham says.
While cautioning that the new radiation delivery system is still far from ready for use in people, Abraham notes that P32 gives off high energy that can penetrate through 5 millimeters of human tissue, making it a good candidate to tackle colon cancer since colon cancer cells can often form large, thick tumors into which drugs may not penetrate very well. In addition, P32-labeled peptides may serve another valuable use: to find small metastases or recurrences of colon tumors while they are still small enough to treat. Images of the body can be taken of the labeled peptides as they bind, revealing where stray tumor cells may be nesting.
Abraham, Meltzer and their team then designed and tested a variety of P32-peptides on 18 normal and cancerous human cell samples. The most potent peptide, MA5, could bind to adenocarcinoma cells, which make up 95 percent of all colon cancers, 150 times more strongly than other cell types and be transferred inside cells within 2 hours.
Johns Hopkins Medical Institutions
Colon Cancer News and Current Colon Cancer Events RSSVariation of normal protein could be key to resistance to common cancer drug
Researchers at the Moores Cancer Center at the University of California, San Diego (UC SD) in La Jolla have found evidence explaining why a common chemotherapy drug, cisplatin, may not always work for every cancer patient. They have shown that when a variant version of a key protein that normally causes cell death is active, patients may be resistant to the cancer-killing drug.
Anti-Cancer Flower Power
Could a substance from the jasmine flower hold the key to an effective new therapy to treat cancer?
Scientists discover major genetic cause of colorectal cancer
About one-third of colorectal cancers are inherited, but the genetic cause of most of these cancers is unknown. The genes linked to colorectal cancer account for less than 5 percent of all cases.
Experimental chemotherapy regimen shows promise in treating advanced lung cancer
A combination of chemotherapy agents that have been tested in other tumor types appears to be a promising alternative to standard treatment for advanced non-small cell lung cancer, according to a report in the August 15 issue of Clinical Cancer Research, a journal of the American Association for Cancer Research.
Exercise Pill is No Replacement for Exercise
Recently, researchers at the Salk Institute for Biological Studies, a research organization focused on biology and its relation to health, published a study in the journal Cell on the results of a substance that increased exercise endurance without daily exertion when tested in mice.
Researchers identify gene responsible for rare childhood disease
The chromosomal abnormality that causes a rare, but often fatal, disorder that affects infants has been identified by researchers at the University of California, San Diego School of Medicine, who happened to treat two young children with the disease in San Diego - two of perhaps a dozen children in the entire country diagnosed with the disorder.
'Smothered' genes combine with mutations to yield poor outcome in cancer patients
Johns Hopkins Kimmel Cancer Center researchers have identified a set of genes in breast and colon cancers with a deadly combination of traditional mutations and "smothered" gene activity that may result in poor outcomes for patients.
Study finds that significant proportion of men told wife's cancer was incurable late or not at all
A study conducted in Sweden found that more than 40 percent of widowers in that country whose wives died from cancer four or five years earlier reported they were either never told that their spouse's cancer was incurable, or they heard this information during the last week of her life.
Different type of colon cancer vaccine reduces disease spread, Jefferson scientists show
Taking advantage of the fact that the intestines have a separate immune system from the rest of the body, scientists at the Kimmel Cancer Center at Jefferson in Philadelphia have found a way to immunize mice against the development of metastatic disease.
Weight-loss surgery can cut cancer risk
Successful bariatric surgery allows morbidly obese patients to lose up to 70 percent of their excess weight and to maintain weight loss.
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