Researchers at the University of California, San Francisco announced on March 12 that they have discovered the SRC enzyme, previously thought to exist only inside cells, also appears on the surface of various tumor cells. This finding could open new avenues for cancer treatment.
The discovery is significant because it reveals a potential new target for immunotherapies. The SRC enzyme has been known for decades as a driver of cancer growth, but its presence outside the cell was unexpected and may allow therapies to attack tumors more precisely.
According to Jim Wells, PhD, professor of Pharmaceutical Chemistry at UCSF and senior author of the paper published in Science, "No one thought to look for it on the outside. Our discovery enables us to test proven immunotherapies on this new tumor target." Researchers found that as cancer cells divide rapidly, their waste disposal systems become overwhelmed. This causes some cellular waste, including SRC, to be expelled onto the cell surface where it becomes accessible to antibody-based therapies.
Corleone Delaveris, PhD, first author of the paper and now at Inversion Therapeutics, said: "We saw that SRC was getting swept out onto the outer membrane, where it sat exposed like a red flag." The team observed that SRC appeared on bladder tumor cells from patients but not on healthy tissue or immune cells. This specificity suggests that targeted therapies could minimize harm to normal cells.
The research team tested antibodies carrying radioactive payloads or designed to summon immune cells against SRC in mice with human tumors. These treatments shrank tumors by killing cancer cells. UCSF has licensed these antibodies and related molecules to Inversion Therapeutics for further development.
Wells said: "We went all the way from the discovery to developing two preclinical therapies that target SRC - and they worked. It's truly exciting." The findings may lead to broader applications in treating different types of cancers if further studies confirm their effectiveness.
