Contagious Cancer: Genome Study Reveals How Tasmanian Devil Cancer Has Spread

tasmanian_devil_cancer_genome Image courtesy of Save the Tasmanian Devil Program

A killer cancer that is threatening to wipe Tasmanian devils off the map for good has been spreading from an original infected female 15 years ago via live cancer cells, according to evidence from genome sequences of the cancer and the animal, published online Thursday in Cell. Finding out how this happened could help save this species from extinction and it could also prepare researchers for the unlikely event that a contagious cancer ever appeared in humans.

The facial cancer, which is spread through bites, has plagued this animal’s precarious population for more than a decade. Tasmanian devils (Sarcophilus harrisii) are the largest surviving carnivorous marsupials and live on Australia’s island state Tasmania. [Read more about this scourge in "The Devil's Cancer," from Scientific American's June 2011 issue.] All of the tumors afflicting the animals today contain cells from one original devil, genetic sequences show. “I call her the immortal devil,” Elizabeth Murchison, a researcher at the Wellcome Trust Sanger Institute and co-author of the new paper, said in a prepared statement. “Her cells are living on long after she died.”

An earlier version of the Tasmanian devil genome was published last year in Proceedings of the National Academy of Sciences and revealed some secrets about why the cancer hasn’t killed off the species already. One of the two devils sequenced, named Cedric, showed resistance to at least two strains of the cancer, although he later succumbed to a third.

“The Tasmanian devil cancer is the only cancer that is threatening an entire species with extinction,” Murchison said. After the first tumor appears on the doomed animals face, it will likely die within three months.

But by turning to genetics, researchers and conservationists hope to be able to find clues to at least slow the cancer’s spread. The researchers studied tumors from 104 tumors collected from Tasmanian devils from various locations on the island and found that there were separate geographic groups of cancer types but that all of them contained cells from the original female. “Sequencing the genome of this cancer has allowed us to catalogue the mutations that caused this cancer to arise and to persist,” Murchison said. More detailed genetic details could point the way to targeted cancer drugs. It might also suggest how the cancer is able to sneak past the immune system and start its explosive growth so quickly.

“Tracing the evolutionary history and spread of this cancer helps us to understand not only what caused this disease but also to predict how it might behave in the future,” David Bentley, chief scientist at Illumina Cambridge, Ltd. and study co-author, said in a prepared statement.

The Tasmanian devil’s cancer has more than 17,000 mutations. “This is fewer mutations that are found in some human cancers and indicates that cancers do not need to be extremely unstable in order to become contagious,” Bentley said. Only one other type of contagious cancer is known a venereal tumor that infects dogs and wolves. The next step is “to use the genome sequence to understand more about how this cancer became transmissible,” Michael Stratton, director of the Wellcome Trust Sanger Institute and study co-author, said in a prepared statement. “Cancers that transmit through populations are obviously incredibly rare, he said, but we should use the Tasmanian devil example to be prepared in the extremely unlikely event that such an epidemic ever occurs in humans.”

Do you follow Scientific American (@SciAm) on Twitter to stay informed on scientific research and discoveries? Please nominate us for a Shorty Award in Science: Vote Here.

Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
© 2012 ScientificAmerican.com. All rights reserved.

View the original article here

Aspirin could beat cancer spread: Australian study

Aspirin and other household drugs may inhibit the spread of cancer because they help shut down the chemical "highways" which feed tumours, Australian researchers said Tuesday.

Scientists at Melbourne's Peter MacCallum Cancer Centre said they have made a biological breakthrough helping explain how lymphatic vessels -- key to the transmission of tumours throughout the body -- respond to cancer.

"We've shown that molecules like the aspirin... could effectively work by reducing the dilation of these major vessels and thereby reducing the capacity of tumours to spread to distant sites," researcher Steven Stacker said.

Doctors have long suspected that non-steroidal anti-inflammatory drugs such as aspirin may help inhibit the spread of cancer but they have been unable to pinpoint exactly how this is done.

By studying cells in lymphatic vessels, the researchers found that a particular gene changed its expression in cancers which spread, but not when the cancer did not spread.

The results published in Cancer Cell journal reveal that the gene is a link between a tumour's growth and the cellular pathway which can cause inflammation and dilation of vessels throughout the body.

Once these lymphatic vessels widen, the capacity for them to act as "supply lines" to tumours and become more effective conduits for the cancer to spread is increased.

But aspirin acts to shut down the dilation of the vessels.

"So it seems like we have found a pivotal junction point in a biochemical sense between all these different contributors," Stacker said.

The discovery could lead to new and improved drugs which could help contain many solid tumours, including breast and prostate cancer, as well as potentially provide an "early warning system" before a tumour begins to spread.

Last year, a study published in medical journal The Lancet found that rates of cancer of the colon, prostate, lung, brain and throat were all reduced by daily aspirin use.

Many doctors recommend regular use of aspirin to lower the risk of heart attack, clot-related strokes and other blood flow problems. A downside of extended daily use is the risk of stomach problems.

mfc/mp/jms

View the original article here

Parents urge more tests as twitches spread at New York school

LE ROY, New York (Reuters) - State health officials have added three more names to a growing list of students in this working-class town who are experiencing mysterious tics and twitching, while authorities on Saturday sought to assure parents the community's high school is safe.

Although the symptoms are typically associated with Tourette Syndrome, that has been ruled out in all but one case, causing fear and confusion among many residents of Le Roy, N.Y., about 50 miles east of Buffalo.

"The building is safe for the community," District Superintendent Kim Cox told several hundred residents gathered in the auditorium of Le Roy Junior-Senior High School on Saturday.

The Le Roy Central School District scrambled to conduct environmental testing for air quality and mold when an initial 12 students developed tics and impulsive verbal outbursts last fall. But state health investigators ruled out environmental factors, latent side-effects from drugs or vaccines like Gardasil, trauma or genetic factors.

Instead, doctors say conversion disorder - once called mass hysteria - is to blame among an expanding list of patients. Three more unconfirmed cases have been added to the original list of students exhibiting the symptoms, and others are being examined.

Air quality and mold surveys at the school have all come back negative, according to district officials and representatives of Leader Professional Services Inc., a company hired to conduct environmental testing at the school after the symptoms first surfaced.

Senior Industrial Hygienist Mary Ellen Holvey on Saturday said air and water tests turned up nothing, and recommended follow-up testing of air inside the school.

She said that would help determine whether a soil review will be conducted - a test demanded by those residents who believe environmental factors are to blame.

One parent, Melissa Cianci, said her daughter no longer wants to attend school in light of the outbreak. She said students should be moved to another location as the investigation continues.

"She doesn't know if it's safe," Cianci said, adding her daughter had perfect attendance prior to the incidents. "I'm done listening to you," she yelled at the panel before storming out, later criticizing the district for being less than candid early in the investigation and demanding that soil tests be conducted of school grounds.

Though there is no evidence of environmental contamination, for some residents environmental concerns were heightened by the district's recent disclosure of six natural gas wells on school property, as well as possible contamination from the nearby site of a 1970 train derailment and chemical spill.

Regarding the wells on school land, William Albert, of the district's law firm Harris Beach, said, "It's not unusual. We're out in the country."

Several representatives of renowned environmentalist Erin Brockovich were barred recently from collecting soil samples near the school by local police.

State health officials note that all of the patients have had significant stress factors, which can worsen the condition. Three of them had pre-existing medical conditions, including one confirmed case of Tourette's Syndrome. Just one of the patients in male.

Congresswoman Kathy Hochul, who represents the district, sent a letter to the environmental Protection Agency on Monday calling for a review of the Superfund site, which the EPA said is regularly monitored, including testing scheduled later this month.

(Editing by Paul Thomasch)

View the original article here