CBM-12EXOSOMAL PTEN DETECTION IN GLIOMA PATIENTS

BACKGROUND: Tyrosine kinases (TKs) are key regulators of intracellular signaling including cellular differentiation and proliferation. Phosphatase and tensin homologue deleted in chromosome 10 (PTEN) is a potent tumor suppressor protein, an inhibitor of PI3K signaling pathway. Gliomas are associated with a reduction or loss of PTEN expression. It has been recently shown that PTEN is transported through exosomes in various cancers. Herein, we report incorporation of PTEN in exosomal glioma cargo for the first time. METHODS: Serum and paired glioma tissue biopsies with a confirmed histopathology were collected as per approved ethics protocol. Both serum exosomal RNA and biopsy tissue RNA was isolated using commercial kits (Invitrogen). PTEN expression was quantified using a semi-nested PCR with GAPDH as an internal control. Clinical pathology was correlated with tissue and exosomal PTEN expression. RESULTS: Analysis of exosomal RNA isolated from exosomes showed the presence of small RNA. Exosomal PTEN was detected in 13 of the 72 glioma patients in the exosomal fraction, confirmed with sequencing. Exosomal PTEN was detected in 26% of Grade II, 22 % of Grade III, and 12% of Grade IV patients. Tissue PTEN could not be detected in 11 of the 72 glioma patients. CONCLUSION: These data suggest that PTEN expression can be detected in exosomes of glioma and that its expression correlates with the extent of tissue grade. Thus, PTEN detection through a simple blood test could be a promising clinical tool for early tumor diagnosis.