'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: Scientists discover an on/off switch for aging cells

add to favorites email to friend print save as pdf

Related Stories

Atomic structure of key muscle component revealed

Jul 24, 2014

Actin is the most abundant protein in the body, and when you look more closely at its fundamental role in life, it's easy to see why. It is the basis of most movement in the body, and all cells and components ...

Rare parasitic fungi could have anti-flammatory benefits

Nov 14, 2012

Scientists at The University of Nottingham have discovered that a rare parasitic fungus that lives on hibernating caterpillars in Tibet could have a role to play in anti-inflammatory drugs for conditions such as asthma.

Why salad helps you say yes to 'NO'

Mar 23, 2011

Disorders of the circulatory system- vascular diseases- are common in the developed world, and can lead to heart attacks, strokes and even death. However, treatments for these disorders, such as bypass surgery and angioplasty, ...

Recommended for you

Scientists discover an on/off switch for aging cells

Sep 20, 2014

(Medical Xpress)—Scientists at the Salk Institute have discovered an on-and-off "switch" in cells that may hold the key to healthy aging. This switch points to a way to encourage healthy cells to keep dividing ...

Gene variant that dramatically reduces 'bad' lipids

Sep 16, 2014

In the first study to emerge from the UK10K Project's cohort of samples from the general public, scientists have identified a rare genetic variant that dramatically reduces levels of certain types of lipids in the blood. ...

New diagnostic method identifies genetic diseases

Sep 16, 2014

People with genetic diseases often have to embark on an odyssey from one doctor to the next. Fewer than half of all patients who are suspected of having a genetic disease actually receive a satisfactory diagnosis. Scientists ...

User comments : 0