Researchers at the Bellvitge Biomedical Research Institute of Bellvitge, the Catalan Institute of Oncology, and the University Hospital of Bellvitge have participated in an international study published recently that describes how exosomes secreted by tumor cells contain protein and microRNA molecules capable of transform neighboring cells into tumoral cells promoting tumor growth.
What are exosomes?
Exosomes are small vesicles which are secreted by all cells and contain proteins and messenger RNAs and microRNAs. At first it was thought that they only functioned as cellular debris warehouses. But in recent years it has been learned that they could have an important role as a messenger between cells of the body. Now many groups focus their research on the role that exosomes could play in various diseases, including cancer.
The study shows that exosomes from tumor cells of breast cancer (and other tumor types such as ovarian and endometrial) are different in size and composition than those of healthy cells. According to the head of the research group of chemoresistance and predictors of tumor response and stromal environment ICO-IDIBELL, Alberto Villanueva, "tumor exosomes contain certain proteins (Dicer, TRBP and Ago2) able to process microRNAs that can alter around the tumor cells transforming them into tumoral cells."
The pathologist of the Department of Pathology at the University Hospital of Bellvitge August Vidal explained that "this tumorigenic transformation depends on Dicer protein that could serve as a marker for the presence of tumor cells, or as a therapeutic target."
In human samples and in mice
Researchers have isolated exosomes from tumors and from blood of patients with breast cancer, and from blood of mice with human tumors grown after breast implantation in mice, called ortoxenogratfs.
"This finding," Villanueva said, "opens the door to developing new biomarkers and new therapeutic strategies exploiting these characteristics of exosomes in breast tumors, and other tumors such as ovarian and endometrial cancer among others."
Illustration: Mice orthotopical breast xenograft serum exosomes. –IDIBELL.
IDIBELL-Bellvitge Biomedical Research Institute News Release (11/13/14)
Science Daily (11/13/14)
Abstract (Cancer Cell; Vol. 26, Issue 5, 707-721 (11/10/14))