Virus linked to fungi & possible cancer connection

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Virus Link to Rare Form of Prostate Cancer Revives

Suspicions of ...

New York Times - United States

.... have speculated that a virus could be involved in

some prostate cancer. ... More than 1,000 viruses,

from humans, animals, plants, fungi and bacteria, have

been ...

COMMENT: if virus from fungi are thought to

contribute to cancer, why isn't there any studies from

cancer groups regarding mold in the environment and

it's connection to cancer?

February 25, 2006

Virus Link to Rare Form of Prostate Cancer Revives

Suspicions of Medical Detectives

By LAWRENCE K. ALTMAN

A team of scientists in Cleveland and San Francisco

said yesterday that they had discovered a new virus in

patients who had a rare form of prostate cancer. The

patients all had a particular genetic mutation.

But the researchers, who reported their finding at a

meeting of the American Society of Clinical Oncology

in San Francisco, do not know whether the virus causes

prostate cancer, infection or any other ailment in

humans. The virus, called XMRV, could prove to be

harmless.

Still, finding a virus in a rare form of prostate

cancer intrigues scientists because of growing

suspicions that prostate cancer might result from

chronic inflammation caused by bacteria or a virus.

Other viruses cause certain cancers of the liver and

the cervix.

If researchers someday prove that a virus causes at

least some prostate cancers, the finding would raise

the possibility of developing new drug therapies and a

vaccine, Dr. A. Klein of the Cleveland Clinic

said in a telephone news conference. Dr. Klein is a

co-author of the report with scientists from the

University of California, San Francisco.

The XMRV virus is closely related to a group of

retroviruses found in mice and known as xenotropic

murine leukemia virus. (Xenotropic means the virus

crossed species.) Though such viruses can cause

disease in animals other than mice, there has been no

documented human infection until the new report.

Prostate cancer causes 30,000 deaths a year in this

country, making it the second-leading cause of cancer

deaths in men, behind lung cancer.

One reason for the uncertainty about the meaning of

the findings is that, so far, the scientists have

searched for XMRV only among patients with familial

prostate cancer. This form is defined as three or more

cases of prostate cancer in a family of first-order

relatives below age 55. This form accounts for 9

percent of all prostate cancers.

Now the researchers want to expand their tests for

XMRV in other human tissues.

The researchers found the virus 25 times more often

among a small group of men with the particular genetic

mutation and prostate cancer than among men without

the mutation.

The discovery came from a collaboration between

scientists in different fields: genetics in Cleveland

and virology in San Francisco.

About 10 years ago, in Cleveland, Dr. H.

Silverman discovered a gene called RNAsel that is

present in all people and that helps fight viruses.

But men with the mutation are at greater risk for

prostate cancer.

Because of the gene's antiviral role, some scientists

have speculated that a virus could be involved in some

prostate cancer.

Two years ago, in San Francisco, Dr. Don Ganem and Dr.

Joe DeRisi created a virus chip with the goal of

discovering unknown viruses that might cause human

disease.

More than 1,000 viruses, from humans, animals, plants,

fungi and bacteria, have been identified. By using a

robot to deposit about a dozen different pieces of DNA

from each of all known viruses, the scientists can

compare the genetic material with that in a sample of

what might contain an unknown virus.

In 2003, the chip technique confirmed that a

previously unknown coronavirus caused SARS.

Human-to-human transmission is much more likely than

contact with mice as the source of the murine virus

detected in the prostate tissue, the researchers said.

The scientists began their collaboration after Dr.

Silverman read about the virus chip. " Bob called me up

and told me about his findings. " Dr. Ganem said in an

interview. " Instantly, we were both thinking the same

thing, " he said, referring to whether the mutation

might be a clue to a viral infection in patients with

familial prostate cancer.

Using the chip, the researchers in California tested

tissue removed at surgery from 86 prostate cancer

patients. Among the 20 prostate tumor samples from men

with mutations in both copies of the RNAsel viral

defense gene, eight — or 40 percent — had the virus.

This compared with only 1 of 66 (1.5 percent) tumors

from men with at least one normal copy of the gene.

Tests showed that the viruses in the patients were the

same, even though there was no relationship between

any of the patients.

" While we can't state that this virus causes prostate

cancer, these are remarkable findings because of the

association of the virus with the mutation, " Dr.

Silverman said.

Three decades ago, the mouse virus was nettlesome to

scientists seeking viral causes of cancer. When they

grew various animal viruses in laboratories, the mouse

viruses often popped up. But because they were usually

contaminants, this line of research was largely

abandoned.

Dr. Ganem said the team was puzzled by a number of

factors. A particular mystery is why laboratory tests

show that XMRV is absent from the cancerous prostate

cells, yet present in surrounding tissue known as

stroma. Another puzzle is why only 1 percent of the

stroma cells are infected.

That small percentage suggests that the virus causes

more extensive infection elsewhere in the body.

In recent years, Dr. Ganem said, scientists have begun

to speculate about the role of stroma in cancer. In

the past, the tissue was thought to have no crucial

function, but scientists now suspect that some

molecules in the stroma play a role in producing

prostate cancer.

The XMRV virus acts differently from viruses known to

cause cancers, Dr. Ganem said. In known links, the

virus is in the cancer cell, not in the stroma, and

every cell in the tumor is infected.

The scientists are sure that infection was linked to

the gene mutation, Dr. Ganem said, adding: " That means

that either people with that mutation are more likely

to acquire infection than others, or that they are

less likely to clear the virus than someone without

it. "

The team hopes to conduct studies to determine what

percentage of men have evidence of the virus and

whether it causes any prostate cancers or other

disease. Future research will also try to determine

any links between the virus and a patient's sexual

activity and personal and family medical history.

The findings will be published in the journal PLoS

Pathogens.

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