Immunotherapy has shown great potential in the treatment of some cancers. However, it does not suit all patients, and some types of medication can cause serious side effects.
Using a new approach to the treatment, scientists from the School of Medicine, University of California San Diego is transformed into cells that produce antibodies to the "factory", which collect and secrete vesicles that contain microRNAs. These small pieces of genetic material weakening a gene that promotes tumor growth. In the mouse mammary tumor treated with the new treatment were significantly smaller than untreated tumors.
The study was published in «Scientific Reports».
"We believe that the new approach can be used in situations where the immunotherapy does not work. The advantage of this type of treatment is that the treatment is localized, ie the patient has fewer side effects. Furthermore, the treatment is durable, i.e. the patient does not need frequent injections or infusion. Perhaps, the new approach will work against a number of different types of tumors, including breast cancer , ovarian, stomach, pancreatic and hepatocellular carcinoma "- the researchers reported.
MicroRNAs do not code for proteins. Instead they bind messenger RNA, which encode the proteins, inhibiting their movement or accelerating their degradation. Normal cells using microRNA to configure a set of genes. MicroRNAs are generally less active in cancer cells, allowing the proteins associated with the growth, "run wild".
In the new study, researchers used miR-335, a microRNA that specifically weakens SOX4, a transcription factor that promotes tumor growth. They added precursor miR-335 to B-cells in vitro. Once inside cells transformed precursor to a mature active miR-335 and its packaged in vesicles - small coated membrane bags that extend from cells. Each cell can produce 100 000 containing miR-335 vesicles per day - enough to treat 10 cancer cells.
To test the new system, the researchers treated human breast cancer cells vesicles with miR-335 in vitro. Then they transplanted tumor cells in mice. After 60 days, 100% (5/5) of mice in the control group had large tumors that while only 44% (4/9) of rodents treated with vesicle-miR-335, developed tumors. On average, the tumor treated mice were more than 260 times less than in the mice from the control group.
In this case, the effect of the treatment was long - miR-335 levels are still elevated in the treated mice 60 days after transplantation of the vesicles and cancer cells.
"We found that even small changes in gene expression of cancer cells after treatment were associated with a specific suppressive effect of molecules that promote tumor growth" - the researchers noted.
The next task of scientists - to ensure that the B cells and vesicles were as close as possible to the tumor. Currently, researchers are working to improve the delivery system, improve treatment efficacy and reduce side effects.