Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A gene that fights cancer, but causes it too

17.05.2011
Over-activation of a single gene promotes leukemia, but its loss causes liver cancer

An international team of researchers, led by scientists at the University of California, San Diego School of Medicine, and the Eastern Hepatobiliary Surgery Hospital in China, say a human gene implicated in the development of leukemia also acts to prevent cancer of the liver.


In this low-magnification micrograph, normal liver architecture is disrupted by hepatocellular carcinoma, the most common type of liver cancer. Fibrotic late-stage cirrhosis is stained blue; tell-tale Mallory bodies (keratin filament proteins) are stained pink. Credit: UC San Diego School of Medicine

Writing in the May 17 issue of the journal Cancer Cell, Gen-Sheng Feng, PhD, UCSD professor of pathology, and colleagues in San Diego, Shanghai and Turin report that an enzyme produced by the human gene PTPN11 appears to help protect hepatocytes (liver cells) from toxic damage and death. Conversely, the same enzyme, called Shp2, is a known factor in the development of several types of leukemia.

"The new function for PTPN11/Shp2 as a tumor suppressor in hepatocellular carcinoma (HCC) stands in contrast to its known oncogenic effect in leukemogenesis," said Feng. "It's a surprising finding, but one that we think provides a fresh view of oncogenesis. The same gene can have oncogenic or anti-oncogenic effects, depending upon cellular context."

Previous studies had determined that PTPN11 was a proto-oncogene. That is, dominant active mutations in the gene had been identified in several types of leukemia patients, as was an over-expression of the gene product Shp2. Feng and colleagues looked to see what happened when Shp2 was knocked out specifically in hepatocytes in a mouse model.

The result wasn't good: The mice got liver cancer.

Strikingly, deficient or low expression of PTPN11 was detected in a sub-fraction of human HCC patient samples by researchers at the Eastern Hepatobiliary Surgery Hospital in Shanghai, China. That work was led by Hongyang Wang, MD, PhD and a professor of molecular biology.

"The liver is a most critical metabolic organ in mammals, including humans," said Feng. "It has a unique regenerative capacity that allows it to resist damage by food toxins, viruses and alcohol. Shp2 normally acts to protect hepatocytes. Removing Shp2 from these liver cells leads to their death, which in turn triggers compensatory regeneration and inflammatory responses. That results in enhanced development of HCC induced by a chemical carcinogen."

Feng said the findings highlight the unique mechanism underlying HCC, but more broadly, they reveal new complexities in how different types of cancer begin. Indeed, the researchers say their work also uncovered pro- and anti-oncogenic activities in a gene transcription factor called Stat3.

"Our results indicate a requirement for Stat3 in promoting HCC development, which is consistent with the literature saying Stat3 is pro-oncogenic. But we also found that deletion of Stat3 in hepatocytes resulted in a modest, but significant, increase in HCC."

Feng said the findings underscore the need for caution in designing therapeutic strategies for treating HCCs and other types of cancers because the answer might also be the problem.

Funding for this study came, in part, from the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institutes of Health and the National Natural Science Foundation of China.

Co-authors of the paper include Emilie A. Bard-Chapeau, UCSD Department of Pathology and Division of Biological Sciences and Sanford/Burnham Medical Institute, La Jolla; Shuangwei Li, Sharon S. Zhang, Helen H. Zhu, Diane D. Fang and Nissi M. Varki, UCSD Department of Pathology and Division of Biological Sciences; Jin Ding, Tao Han and Hongyang Wang, Laboratory of Signal Transduction, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China; Frederic Princen and Beatrice Bailly-Maitre, Sanford/Burnham Medical Research Institute; Valeria Poli, Department of Genetics, Biology and Biochemistry, University of Turin, Italy.

Scott LaFee | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden

nachricht The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>