'Innocent bystanders' can be the cause of tumor development

Mar 03, 2008

Tumor growth has commonly been viewed as a result of mutations in a given cell that will therefore proliferate uncontrollably. However, a study conducted at the University of Helsinki, Finland, has demonstrated that in certain type of gastrointestinal polyps, the cause of tumor development are mutations in the smooth muscle cells, previously regarded as “innocent bystanders”. The results emphasize the importance of interactions between tissue types, and open up possibilities to develop new treatment strategies targeting the intercellular signaling.

Gastrointestinal polyps are tumors that can both block the digestion and progress to cancer. The cell-type making up the bulk of the polyps and therefore responsible for the adverse effects are the hyper proliferating epithelial cells, which normally line the inner surface of the gastrointestinal tract.

Therefore studies addressing the possible mechanisms of polyp development have traditionally focused on epithelial cells. However, the results from professor Tomi Mäkelä’s research group demonstrate that origin of at least certain polyps is found elsewhere than in the pathologically growing epithelium. By restricting the mutations in mice to the smooth muscle cells that encircle the epithelium, researcher Pekka Katajisto discovered that deletion of the tumor suppressor gene Lkb1 leads to excessive proliferation of neighboring epithelial cells and tumor development.

The results demonstrate that Lkb1 deletion in smooth muscle cells disturbes the signaling between cells. Normally the smooth muscle cells appear to hold-back the proliferation of their neighboring epithelial cells by signals mediated by the growth factor TGFß, but this signaling is reduced in the studied tumors. As a consequence, the epithelium undergoes accelerated proliferation. The same intercellular signaling defect was also noted in the Peutz-Jeghers polyposis caused by hereditary LKB1 mutations.

The study results has been published in Nature Genetics (online) 2nd March, 2008.

Source: University of Helsinki

Explore further: Computational biologists simplify diagnosis for hereditary diseases

add to favorites email to friend print save as pdf

Related Stories

NASA Mars spacecraft prepare for close comet flyby

45 minutes ago

NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data, as Comet C/2013 A1 Siding Spring heads toward a close flyby of Mars on Oct. 19.

Giant anteaters kill two hunters in Brazil

48 minutes ago

Giant anteaters in Brazil have killed two hunters in separate incidents, raising concerns about the animals' loss of habitat and the growing risk of dangerous encounters with people, researchers said.

US plans widespread seismic testing of sea floor

51 minutes ago

(AP)—The U.S. government is planning to use sound blasting to conduct research on the ocean floor along most of the East Coast, using technology similar to that which led to a court battle by environmentalists in New Jersey.

Giant crater in Russia's far north sparks mystery

16 minutes ago

A vast crater discovered in a remote region of Siberia known to locals as "the end of the world" is causing a sensation in Russia, with a group of scientists being sent to investigate.

Recommended for you

Gene research targets scarring process

Jul 28, 2014

Scientists have identified three genes that may be the key to preventing scar formation after burn injury, and even healing existing scars.

Researchers find new mechanism for neurodegeneration

Jul 24, 2014

A research team led by Jackson Laboratory Professor and Howard Hughes Investigator Susan Ackerman, Ph.D., have pinpointed a surprising mechanism behind neurodegeneration in mice, one that involves a defect in a key component ...

User comments : 0