Navigation Links
St. Jude identifies the specific cell that causes eye cancer, disproving long-held theory
Date:10/18/2007

Investigators at St. Jude Children's Research Hospital have identified the cell that gives rise to the eye cancer retinoblastoma, disproving a long-standing principle of nerve growth and development. The finding suggests for the first time that it may one day be possible for scientists to induce fully developed neurons to multiply and coax the injured brain to repair itself.

A report of this work appears in the Oct. 19 issue of the journal Cell. Michael Dyer, Ph.D., an associate member in the St. Jude Department of Developmental Neurobiology, is the reports senior author.

Retinoblastoma arises in the retinathe multi-layered, membrane lining the back of the eye that responds to light by generating nerve impulses that are carried into the brain by the optic nerve.

The immediate importance of the St. Jude finding is that it unexpectedly showed that retinoblastoma can arise from fully matured nerves in the retina called horizontal interneurons. This disproves the scientific principle that fully formed, mature nerves cannot multiply like young, immature cells, Dyer said. Human neurodegenerative disorders such as Alzheimers disease can occur when differentiated nerves in the brain try to multiply, and in the process, trigger a self-destruct program called apoptosis. Differentiation is the process by which cells lose their primitive, stem-cell-like properties that include the ability to grow and multiply, and instead develop specialized shapes and functions.

For the past 100 years, its been ingrained among scientists that differentiated mature nerves are so elaborate that they cant divide, and if they try to divide, they undergo apoptosis, Dyer said. There was no exception to this rule until now. This is the first time that anyone has shown that under certain conditions, a fully mature and differentiated nerve can undergo cell division and multiply.

The discovery that fully differentiated horizontal interneurons can multiply to form retinoblastoma also challenges the established scientific belief that cancer cells are most aggressive when they are undifferentiated, Dyer said. For example, the leukemic cells of chronic myelogeneous leukemia (CML) are much less aggressive when they are differentiated; and it is generally not aggressive until the tumor cells sustain mutations that block differentiation.

On the contrary, we showed that when certain genes are inactivated in the retina, horizontal neurons that are already differentiated and fully integrated into the brain can start multiplying rapidly and produce a very aggressive cancer, Dyer said. This opens an exciting new chapter in the study of neurons and brain tumors.

An important implication of this finding is that if researchers were able to alter the activity of certain genes in fully developed neurons, they might be able to trigger them to multiply temporarily and replace the neighboring neurons that were lost as a result of neurodegenerative diseases such as Alzheimers, Dyer said. Having nerves duplicate themselves might be more efficient than trying to stimulate nerve replacement by inserting stem cells into the brain, since the existing nerves would already be in the right place to restore missing brain cells, he said. However, there is still a lot of research required to determine if it is possible to control gene activity to make this approach practical.

Dyers group made their discovery by developing different populations of mice whose retinas lacked one or more members of the Rb family of genes that include Rb, p107 and p130. This family of related genes is critical to the ability of an immature cell to stop dividing and begin to differentiate so it acquires certain specific characteristics required to do its job in the body.

The St. Jude researchers showed that when the mouse retina had reduced Rb family function, fully differentiated horizontal neurons could multiply while retaining all of the differentiated features of normal horizontal neurons.

As part of the study, the St. Jude team conducted microscopic and biochemical studies to prove that the multiplying cells were horizontal interneurons. Using such techniques, the researchers showed that as the horizontal interneurons multiplied their numbers up to 50-fold, they maintained their normal position in the retina as well as their normal connections to other cells.

If the horizontal interneuron cell division was allowed to proceed unchecked, highly differentiated tumors formed that resembled normal horizontal neurons. Unexpectedly, these tumors were aggressive and spread rapidly.

The investigators concluded that the Rb familys only task is to prevent mature horizontal interneurons from multiplying as they did when they were immature cells.


'/>"/>

Contact: Summer Freeman
summer.freeman@stjude.org
901-495-3061
St. Jude Children's Research Hospital
Source:Eurekalert

Related biology news :

1. Study identifies predictors of HIV drug resistance in patients beginning triple therapy
2. New lab technique identifies high levels of pathogens in therapy pool
3. Study identifies gene in mice that may control risk-taking behavior in humans
4. Researcher at UGA College of Veterinary Medicine identifies new way of combating viral diseases
5. U. of Colorado researcher identifies tracks of swimming dinosaur in Wyoming
6. Model identifies genes that induce normal skin cells to become abnormal
7. New study identifies key gene in development of connections between brain and spinal cord
8. New HIV study identifies high-risk subgroups of adolescents
9. Research identifies protein in mice that regulates bone formation
10. Study identifies new role for breast cancer susceptibility gene
11. New strategy rapidly identifies cancer targets
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/3/2016)... Lithuania , May 3, 2016  Neurotechnology, ... released the MegaMatcher Automated Biometric Identification System ... of large-scale multi-biometric projects. MegaMatcher ABIS can process ... accuracy using any combination of fingerprint, face or ... MegaMatcher SDK and MegaMatcher Accelerator ...
(Date:4/28/2016)... -- First quarter 2016:   , Revenues ... first quarter of 2015 The gross margin was 49% ... and the operating margin was 40% (-13) Earnings per ... from operations was SEK 249.9 M (21.2) , Outlook ... 7,000-8,500 M. The operating margin for 2016 is estimated ...
(Date:4/26/2016)... , April 27, 2016 ... "Global Multi-modal Biometrics Market 2016-2020"  report to their ... , The analysts forecast the global ... of 15.49% during the period 2016-2020.  ... of sectors such as the healthcare, BFSI, transportation, ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... Houston Methodist Willowbrook Hospital has signed ... to serve as their official health care provider. ... will provide sponsorship support, athletic training services, and ... volunteers, athletes and families. "We are ... and to bring Houston Methodist quality services and ...
(Date:6/23/2016)... , June 23, 2016  The Prostate Cancer Foundation (PCF) is ... treatments and faster cures for prostate cancer. Members of the Class of 2016 ... countries. Read More About the Class of 2016 PCF ... ... ...
(Date:6/23/2016)... SAN FRANCISCO , June 23, 2016   ... it has secured $1 million in debt financing from ... to ramp up automation and to advance its drug ... for its new facility. "SVB has been ... goes beyond the services a traditional bank would provide," ...
(Date:6/23/2016)... , ... June 23, 2016 , ... STACS DNA Inc., ... Leader at the Arkansas State Crime Laboratory, has joined STACS DNA as a Field ... DNA team,” said Jocelyn Tremblay, President and COO of STACS DNA. “In further expanding ...
Breaking Biology Technology: