Inside job. When mice with cancer cells which have a green fluorescent protein within them were given antibody against GFP, they have developed less lung tumors compared to control mice ( left ).
Ke Guo et al., Science Translational Medicine, 3 (7 September 2011)
Researchers may have found a way to get inside of head cancer or at least his body. The cancer cell has long been considered impervious to antibodies that could target for destruction. But a new study suggests that some antibodies may pass after all, which could open a vast new range of cancer treatments.
When a foreign virus or bacteria enters the body, immune cells start cranking out antibodies, which latch onto the invaders, signaling the immune system of the ship. The antibodies may also be used to treat cancer, for example, the drug Herceptin against breast cancer is an antibody that targets the HER2 receptor, a protein on the surface of breast tumor cells stimulates the growth of cells. However, researchers have not tried to develop drugs against cancer proteins in cells because they thought that the antibodies were too large to pass through the membrane of most cell types.
The new study challenges conventional wisdom. Cancer biologist Qi Zeng of the Institute of Molecular Biology and Cell Singapore and colleagues first injected mice with cancer cells so that tumors began to form. Two days later they started to inject the mice twice per week with antibody to one of the two proteins present in cancer cells: PRL-3 or mT. Over 17 days, the mice treated with the antibody lost weight more slowly and has developed metastatic tumors less than control mice.
The Singapore team also tried a different strategy: Before the mouse cancer, they injected either PRL-3 mT or so that their immune systems would make its own antibodies against these proteins . This style vaccine treatment has slowed the spread of cancer and, in one experiment, extended the life span of mice by 20%, the team published today in Science Translational Medicine .
Using antibodies to target cancer intracellular proteins could "expand the scope to tailor cancer therapy, as well as the advent of a new era of vaccines against the custom cancer," says Zeng. his team recognizes, however, that he did not understand how the treatment works. It is possible that some of the target proteins in cancer cells are somehow transported to the cell surface, and, as with Herceptin, the latch and trigger the immune system to kill cancer cells antibodies. Or antibodies could enter cancer cells and cause them to self-destruction, as has been observed with certain autoimmune diseases.
immunologist Mark Smyth from the Peter MacCallum Cancer Centre in Melbourne, Australia, is skeptical that the antibodies are really slipped inside the cancer cells. the results "are quite heretical in terms of what we know about the immunology, "he said. Yet cancer researcher Michel Tremblay of McGill University in Montreal, Canada, who studies PRL-3 and related proteins, said the study shows promise. The work is "exciting" because it suggests a more specific way of targeting these internal cell proteins that supposedly small molecule drugs, he said, not well so far.
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