One of the most common types of brain tumors in adults, glioblastoma multiforme, is one of the most devastating. Even with recent advances in surgery, radiation and chemotherapy, the aggressive and invasive tumors become resistant to treatment, and median survival of patients is only about 15 months. In a study published in Neuro-Oncology, researchers at Mayo Clinic identify an important association between the naturally occurring enzyme Kallikrein 6, also known as KLK6, and the malignant tumors.
Our study of Kallikrein 6 showed that higher levels of this enzyme in the tumor are negatively associated with patient survival, and that the enzyme functions by promoting the survival of tumor cells," says senior author Isobel Scarisbrick, Ph.D., of Mayo Clinic's Department of Physical Medicine and Rehabilitation.
The findings introduce a new avenue for potential treatment of deadly glioblastomas: targeting the function of KLK6. The tumor cells became more susceptible to treatment when researchers blocked the receptors where the KLK6 enzyme can dock and initiate the survival signal.
Researchers looked at 60 samples of grade IV astrocytomas -- also known at this stage as glioblastomas -- as well as less aggressive grade III astrocytomas. They found the highest levels of KLK6 were present in the most severe grade IV tumors. Looking at the tumor samples, researchers found higher levels of KLK6 associated with shorter patient survival. Those with the highest levels lived 276 days, and those with lower levels lived 408 days.
"This suggests that the level of KLK6 in the tumor provides a prognosticator of patient survival," Dr. Scarisbrick says.
The group also investigated the mechanism of the enzyme to determine whether it plays a significant role in tumor growth. Researchers also found glioblastoma cells treated in a petri dish with KLK6 become resistant to radiation and chemotherapy treatment.