Cancer therapy may treat kidney disease

UC SANTA BARBARA (US) — A transcription factor known to be an important drug target for cancer therapy may also be effective in treating inherited kidney disease.

Autosomal-dominant polycystic kidney disease, or ADPKD, is characterized by the proliferation of cysts that eventually debilitate the kidneys, causing kidney failure in half of all patients by the time they reach age 50.

The disease afflicts more than 600,000 people in the U.S. and 12 million people worldwide.

Currently, no treatment exists to prevent or slow cyst formation, and most ADPKD patients require kidney transplants or lifelong dialysis for survival, says Thomas Weimbs, associate professor of molecular, cellular and developmental biology at University of California, Santa Barbara

The research is published in the journal Proceedings of the National Academy of Sciences.

Weimbs and colleagues discovered that polycystin-1, a protein that is mutated in ADPKD patients, regulates a well-known transcription factor called STAT3. Transcription factors transcribe information from DNA to RNA, from specific genes.

“The clinical significance of these discoveries lies in the fact that STAT3 is also known to be aberrantly activated in many forms of cancer and is considered an important drug target for cancer therapy,” Weimbs says.

“Numerous STAT3 inhibitors are currently being developed and tested, and several experimental drugs are already available.

Our results suggest that STAT3 activation is a driving force for the cyst growth that leads to polycystic kidneys in ADPKD. Therefore, STAT3 may be a highly promising drug target for the treatment of ADPKD.

STAT3 is a signaling molecule that is activated in response to many different growth factors binding to specific receptors on the surface of kidney cells.

In response to these growth factors hitting the cell, STAT3 is activated, causing it to turn on the expression of certain genes, further causing the cells to proliferate, as they do in cancer.

“In polycystic kidney disease, we have strong proliferation, but it is similar to having benign tumors––where the tumor stays in place,” says Weimbs.

“The cysts keep growing, but they do not metastasize or invade other tissues as do cancerous tumors.

“Polycystic kidneys are full of small, benign tumors or cysts. This is still very destructive, because eventually the disease will destroy the kidney.”

The research team is currently testing STAT3 as a drug target in mice with ADPKD.

Researchers from Johns Hopkins University contributed to the study, that was funded by the National Institutes of Health.

Activated STAT3 in a mouse polycystic kidney is stained dark brown. (Credit: Weimbs lab)

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