Another of my mildly **OT** 'editorials'? Actually, pretty interesting stuff, IMO! Pax et Bonum, mch
BALTIMORE, MD -- March 2, 1999 -- Nearly 90 percent of prostate cancers are
linked to a previously unsuspected but common genetic process that could be
reversible, Johns Hopkins researchers say.
The process looks to be a fundamental one in cancer and appears in other common
forms of the disease, like breast cancer.
Unlike cancers due to mutations that make structural changes in a gene, such as the
colon cancers that run in families, most prostate cancer may involve a process called
gene switching, the researchers said. Switching occurs when certain members of a
family of genes are switched on while others in the family shut down.
"It's a process common during embryonic development," said molecular pathologist
Shrihari Kadkol, M.D., Ph.D., one of the researchers in a study appearing today in
Nature Medicine. "We believe this is the first time anyone's definitively linked gene
switching within a family of genes, with cancer."
"Most important is that someday, it's likely we can reverse switching with drugs," said
molecular pathologist Gary Pasternack, M.D., Ph.D., who led the Hopkins research
team. "This means one of the commonest cancers in men has the potential of being
corrected without using typical gene therapy."
In their work, the scientists used molecular probes to highlight and compare the gene
activity in cancer patients' normal prostate tissue with that of their tumours. The
investigators found clear evidence that a gene called pp32 was switched on in normal
cells but generally switched off in cancer cells. Earlier studies by the team showed
pp32 acts as a suppressor and keeps cells from turning malignant.
Yet close relatives of the gene, to the researchers' surprise, act like pp32's genetic evil
twins and encourage tumour growth. The pp32r1 and pp32r2 genes are present and
turned on in perhaps 90 percent of the prostate cancers the team studied.
"We first thought pp32 had just mutated but the types of differences between it and the
variant genes told us this wasn't the case," Kadkol said.
The researchers added switching could be a fundamental process in cancer and they've
already linked it with common forms of breast cancer. "In the breast cancer patients
we've examined we saw this same pp32 switching pattern," Kadkol explained.
"If we can understand how the switching process works, what controls it we can
potentially reverse it,” Pasternack added. "That's our next task."
If their work goes smoothly, he adds, they could screen and find drugs for this purpose
within two years. Then the candidate investigational drug would undergo the usual
FDA-sponsored tests in people.
"We also believe this work may have a role in diagnosis or in predicting disease
outcome," Pasternack said. "Prostate specific antigen, the present common screen for
prostate cancer, doesn't always tell the complete story or, particularly in older men,
doesn't let us make a clear prognosis. This might help." |
