Salmonella does not exactly enjoy a good reputation as it is deemed pathogenic and often implicated in food poisoning cases. But what happens when you recruit the bacterial strain in the mission to kill tumors?
Scientists from Duke University genetically tweaked salmonella to help scour and destroy tumors, a development that can potentially help fight the deadliest form of brain cancer.
Using genetically modified Salmonella typhimurium, tests reflected a 20 percent survival rate among rats in a 100-day period, roughly equating to 10 years in humans.
The Scourge Of Glioblastoma
Experts are looking for new treatments for glioblastoma, the most aggressive form of the cancer.
The blood-brain barrier, which is a protective layer that separates brain tissue from blood vessels, makes it difficult for drugs to work effectively, while surgery can leave small remnants that can eventually develop into new tumors. Chemotherapy and radiation therapy — the most recommended for all kinds of the condition — can kill the leftover tumor cells post-surgery.
“[S]ince few survive a glioblastoma diagnosis indefinitely, a 20 percent effective cure rate is phenomenal and very encouraging,” said study author and Ph.D. student Johnathan Lyon in a statement.
Currently, glioblastoma patients survive 15 months at an average, while a mere 10 percent live five years after getting diagnosed.
Earlier this year, a new drug has been discovered by scientists to potentially treat glioblastoma multiforme, a grade IV brain cancer deemed the most fatal because of its invasive nature. It may emerge in any of the brain’s lobes and can manifest mostly in adults through symptoms like nausea, continued headaches, blurred vision, appetite loss, vomiting, personality changes, and memory loss, to name a few.
How The Bacteria Worked
The team injected a detoxified strain of salmonella into rat brains, as previous research showed that bacterial presence can cause the immune system to recognize and start attacking tumors. The selected strain was lacking in the important enzyme purine, which forced the bacteria to find resources elsewhere.
Tumors happened to be a rich purine source, leading bacteria to troop to them.
In another series of genetic maneuverings, the team led the bacteria to give off compounds azurin and p53, which instruct cell death with low oxygen levels present. This was an opportune time since cancer cells multiply rapidly and tumors, as a result, had environments starved of oxygen.
As they are detoxified, the bacteria were not expected to mess with the immunity and cause disease, since their food source was practically destroyed once the tumors are killed off.
In the remaining 80 percent that failed to survive, the novel treatment did not alter length of survival, and the team speculated that either the bacteria worked inconsistently or the aggressive growth of tumors outwitted the agent.
The next step for the researchers, who discussed their findings in the journal Molecular Therapy–Oncolytics, is to condition the bacteria to produce various drugs that might induce stronger tumor reactions.
Salmonella can cause serious, sometimes fatal infections among young children, the elderly, sick and immune-compromised persons, and usually pass after four to seven days without being treated in health individuals.
