A novel strategy for targeting tumors

Xiaohua Peng, an assistant professor of chemistry and biochemistry, looks for new drugs that destroy the DNA of cancer cells exclusively. Current drugs target the DNA of all cells.

In designing better drugs to treat cancer, Xiaohua Peng’s goal is to kill the tumor cells – not the surrounding healthy cells.

By exploiting two distinctive features of tumors, Peng, a UWM biochemist has developed compounds that can “recognize” and release active drugs only to cancer cells.

“The compounds we’ve developed are not toxic by themselves,” she says. “They are activated under tumor-specific conditions – increased oxidative stress and hypoxia [a lack of oxygen].”

For her novel strategies in designing tumor-targeting drugs, Peng has recently received a Shaw Scientist Award from the Greater Milwaukee Foundation. The Shaw Scientist program awards unrestricted grants of $200,000 each year to scientists from UWM and UW-Madison who are working to advance important research in genetics, biology, biochemistry and cancer.

Oxidative stress occurs naturally in the body during processes like metabolism. But in cancer, cells are growing and dividing so fast that the dramatically quicker pace of metabolism leads to formation of high levels of hydrogen peroxide and free radicals, causing cellular damage and disease.

Peng has created two compounds that release a chemotherapy agent at the exact site of increased oxidative stress. The compounds she and her lab members have developed using this mechanism showed a 60-90% inhibition of various kinds of cancer cells, while normal cells were not affected.

Regions of hypoxia are also characteristic of tumors. These form in parts of the tumor farther removed from the blood vessels that supply oxygen. So Peng is creating drugs that induce damage to the cancer cells’ DNA under conditions of little or no oxygen.

There is a particular interest in focusing on hypoxia for cancer treatment, she says, because low oxygen supply has been associated with cancer cells’ resistance to radiation treatment.

Peng received a bachelor’s degree from China’s Nanchang University and a Ph.D. from the University of Osnabrueck in Germany. As a postdoctoral fellow at Johns Hopkins University, she studied DNA damage and repair. In 2010, she received a research award from the National Institutes of Health.

The Shaw Scientist program started in 1982 thanks to a $4.3 million bequest from Dorothy Shaw, widow of James Shaw, a prominent Milwaukee attorney. In addition to $2 million in special grants, the fund has given out more than $11 million to 60 scientists whose research might one day lead to new drugs and treatments.