Tumor-derived exosomes (TDEs) as communicators for cancer development and metastasis.

Abstract

e13031 Background: Comprehensive targeting of cancer communication through inhibition of Tumor-derived exosomes (TDEs) secretion by tumor cells and blocking the selective uptake by recipient cells could potentially control cancer progression. We evaluated the effect of inhibiting TDEs secretion on restricting tumor progression. Methods: Cells of triple-negative breast cancer (MDA MB-231) were cultured in a conditioned culture medium either supplemented with or without 100 µg/ml of pantoprazole for 24 hours. TDEs were isolated using exosome isolation kit from conditioned culture media harvested 24 hours after treating cells with pantoprazole. Transmission Electron Microscope (TEM), and Western blot analysis were used to characterize TDEs, while micro-RNA analysis was performed to assess TDEs cargo. Cell proliferation analysis for the experiment and control groups were conducted on day 3 of cell culture. A 2-tailed Student's unpaired t-test with a 95% confidence interval (CI) with a p-value less than 0.05was used to compare the means of two data sets that were taken between the experimental and the control groups. Results: The assessment conducted using the TEM scanning, and Western Blot analysis verified that the particles we isolated were indeed TDEs. Pantoprazole reduced the proliferation of MDA MB-231 cells. The mean difference in cellular proliferation between the experimental and control groups was -9000 ± 2887 cells/ml (S.E), (P-value = 0.089). The 95% CI was also determined to be (-21421, 3421). Pantoprazole also inhibited TDE secretion, the mean difference in TDE secretion between the experimental group and the control was -3.697 x 10 9 ± 3.722 x 10 8 particles/ml (S.E), P-value = 0.01 and the 95% CI was -5.2 x 10 9 to -2.1 x 10 9 . Furthermore,, pantoprazole was found to reduce the negative surface charge of TDEs. The mean difference in zeta potential between the experimental and control groups was 4.1 ± 0.57 mV (S.E), with a 95% CI ranging from 1.64 to 6,571, and a P-value was 0.019. This indicates that pantoprazole affected the surface charge of TDEs, by rendering them less negative hence affecting the electrostatic binding of TDEs to targeted cells, consequently impairing their uptake. The evaluation of molecular cargo shuttled by TDEs indicated that TDEs carries oncogenic biomolecules that support tumor growth and metastasis. In our research, we identified hsa-miR-372-3p, which is transported by TDEs and is essential in the carcinogenesis of several human cancers. Conclusions: Our preliminary work established that inhibition of TDEs secretion restricted growth of cancer cells by impairing exchange of oncogenic cargo. A novel and comprehensive strategy of targeting TDEs secretion and uptake by recipient cells is required for effective treatment of cancer.