Advertisement

A complement for cancer?

A protein belonging to part of the immune system that researchers once hoped to harness to attack cancer cells actually spurs tumor growth, according to a study reported in linkurl:__Nature Immunology.__;http://www.nature.com/ni/journal/vaop/ncurrent/full/ni.1655.html Researchers knocked out a receptor for one of a group of 30 proteins called linkurl:complement proteins,;http://www.the-scientist.com/article/display/23823/ part of the body's normal immune defense repertoire, and observed decrea

By | September 29, 2008

A protein belonging to part of the immune system that researchers once hoped to harness to attack cancer cells actually spurs tumor growth, according to a study reported in linkurl:__Nature Immunology.__;http://www.nature.com/ni/journal/vaop/ncurrent/full/ni.1655.html Researchers knocked out a receptor for one of a group of 30 proteins called linkurl:complement proteins,;http://www.the-scientist.com/article/display/23823/ part of the body's normal immune defense repertoire, and observed decreased tumor growth in a mouse model. "This elegant study puts complement in the row of factors that can enhance tumor growth," said Arko Gorter, an immunologist at Leiden University Medical Center in the Netherlands, who was not involved in the study. Complement cascade is made up of about 30 proteins that cleave one another in a series of reactions that radiates from an initial binding site on a pathogen. Best known for its action against bacteria, complement proteins can kill a bacterium without the help of immune cells by burrowing into the bacterial membrane and creating a doughnut-shaped hole. Researchers had thought complement could be used to fight cancers as part of an antibody-based vaccine, as antibody binding is one of the factors that can set off a complement cascade. However, some complement components, such as complement 5a (C5a), act as strong mediators of inflammation. Because in some cases inflammation can promote cancer growth, John Lambris at the University of Pennsylvania and colleagues decided to investigate whether C5a instigated tumor growth through an inflammatory pathway. Lambris' team developed a knock-out mouse for the C5a receptor, which is expressed on a number of tissue types. They observed less tumor growth, as well as an increase in anti-tumor CD8+ T cells. The result suggested that the absence of the C5a receptor on suppressor cells blocks the activation of these cells, allowing the tumor fighting cells to attack the tumor. But according to Gorter, this mechanism may not be the only way that complement excites tumor growth. Tumor microenvironments are complex, said Gorter: "A tumor consists of the real cancer cells, the stroma, and a third component: the inflammatory cells," which can be active or suppressed. While it's clear that complement plays an important role in tumor growth, given the complexity of the tumor microenvironment, it's not completely clear how complement exerts its function, or what triggers it, he said. What remains to be seen, said Gorter, is "how general this mechanism is." Is the C5a effect the researches observed particular to the mouse model used? Will it be true for other cancers? Would it translate to human disease? Despite these questions, which must be addressed with further studies, said Gorter, "It is still an impressive study showing to my knowledge for the first time that complement (C5a) can promote tumor progression." Correction (September 30): When originally posted, the article read that a knockout of one of a group of nine proteins resulted in a decrease in tumor growth. The paragraph should have read that a receptor for one of the 30 proteins was knocked out, resulting in a decrease - rather than an increase - in tumor growth. The problem was corrected. __The Scientist__ regrets the error.
Advertisement

Comments

Avatar of: anonymous poster

anonymous poster

Posts: 1

September 30, 2008

hi,\n\nI think there is a typing error in this section:\n\n"Researchers knocked out one of a group of nine proteins called complement proteins, part of the body's normal immune defense repertoire, and observed INCREASED tumor growth in a mouse model."\n\nIn this context INCREASED is wrong, it's rather DECREASED instead or do I have misunderstood this?
Avatar of: anonymous poster

anonymous poster

Posts: 5

September 30, 2008

Not only did the story actually report a decrease in tumor growth, but the knock-out was of a complement RECEPTOR not the complement protein itself. Doesn't anyone edit these stories?
Avatar of: Adrian Gonzalez

Adrian Gonzalez

Posts: 2

October 2, 2008

Tumors.... a tumor is our body's way of protecting itself from cancer. Just like a scab is our bodies way of protecting a wound. Tumors for years have been thought to be "bad" and the allopathic world always wants to cut the tumor out or shrink it. Is it possible that by enhancing the immune system, we may see an increase in tumor growth until the problem is eradicated by other means or (oh my) the bodies own defenses?

Follow The Scientist

icon-facebook icon-linkedin icon-twitter icon-vimeo icon-youtube
Advertisement

Stay Connected with The Scientist

  • icon-facebook The Scientist Magazine
  • icon-facebook The Scientist Careers
  • icon-facebook Neuroscience Research Techniques
  • icon-facebook Genetic Research Techniques
  • icon-facebook Cell Culture Techniques
  • icon-facebook Microbiology and Immunology
  • icon-facebook Cancer Research and Technology
  • icon-facebook Stem Cell and Regenerative Science
Advertisement
Advertisement
Life Technologies