Old Blood Pressure Drug Shows Remarkable New Promise Against Deadly Brain Cancers

In a stunning development for cancer research, scientists have uncovered a novel function for one of the oldest and most widely used medications for high blood pressure. The drug, hydralazine, previously a cornerstone in treating hypertension and preeclampsia—a serious pregnancy complication—may now offer a new weapon against aggressive brain tumors like glioblastoma.

Uncovering a Hidden Mechanism

The research, published in the prestigious journal Science, was led by a team at the University of Pennsylvania. They pinpointed that hydralazine works by inhibiting a crucial enzyme known as 2-aminoethanethiol dioxygenase (ADO). This enzyme acts as a vital oxygen sensor within the body, triggering immediate biochemical responses when oxygen levels drop.

“It’s one of the oldest vasodilators ever developed, and it remains a first-line treatment for preeclampsia,” noted Kyosuke Shishikura, a physician-scientist at the University of Pennsylvania. Despite its widespread use, the precise molecular mechanism behind its effectiveness had remained elusive until now.

Megan Matthews, a postdoctoral advisor on the project, explained that the ADO enzyme acts like an alarm system, signaling when oxygen levels dip. What hydralazine does is effectively silence this alarm by binding to and inhibiting ADO. This inhibition prevents the degradation of key regulatory proteins, known as RGS proteins, allowing them to accumulate.

The consequence of this protein buildup is profound: blood vessels are signaled to relax, which lowers intracellular calcium levels—a critical regulator of vascular tension. This leads to the relaxation of smooth muscle in blood vessel walls, ultimately reducing blood pressure.

A New Frontier in Cancer Treatment

The research also shed light on ADO’s role in the survival of glioblastoma cells. In the oxygen-deficient environment of a tumor, ADO helps cancer cells adapt their metabolism. While high levels of ADO have been linked to tumor aggressiveness, a truly effective inhibitor for studying its effects was missing until now.

By blocking ADO, hydralazine not only influences vascular function but crucially, it induces a state of senescence in glioblastoma cells. Senescence is a state where cells stop dividing, effectively halting tumor growth without causing additional inflammation—a common challenge with other treatments—or leading to resistance.

This discovery holds significant implications for both oncology and cardiovascular medicine. Collaborations with scientists from the University of Texas, who used X-ray crystallography to visualize hydralazine’s interaction with ADO, and neuroscientists from the University of Florida, who assessed the drug’s impact on brain tumor cells, were instrumental in these findings.

Future Directions and Broader Impact

“Understanding hydralazine’s molecular mechanism opens pathways towards safer and more selective treatments for pregnancy-related hypertension, with the potential to improve outcomes for high-risk patients,” Matthews stated. The research also paves the way for developing new, more targeted ADO inhibitors that could potentially cross the blood-brain barrier, enhancing the treatment of brain tumors while minimizing side effects.

The team plans to design highly selective ADO inhibitors that can precisely target brain tumor tissue. This research exemplifies the ongoing effort within the scientific community to delve deeper into the mechanisms of established treatments, uncovering new therapeutic applications that could significantly impact public health.