PB2106 LOCKED NUCLEIC ACID MODIFIED OLIGONUCLEOTIDE MIMICKING MIR‐15A SUPPRESSES TUMOR CELLS PROLIFERATION IN VITRO

Background: Recent studies have highlighted not only the importance of these genetic events but also epigenetic aberrations including DNA methylation, histone modifications, and non‐coding RNAs in the biology of multiple myeloma (MM). Our previous study has shown that non‐coding RNA miR‐15a inhibited the proliferation and promoted the apoptosis of MM cells. The level of miR‐15a was down‐regulated in MM cells and correlated with poor survival of myeloma patients. So, we speculated that up‐regulation the level of miR‐15a would promote MM cells death and prolong patient survival. Aims: To identify whether oligonucleotide mimicking miR‐15a (OMM‐15a) would be worked as an effective agent in the treatment of multiple myeloma and other cancer cells. Methods OMM‐15a was artificial synthesized in two different forms, the native form and the modified form with locked nucleic acid at the both end of native OMM‐15a (LNA‐OMM‐15a). The anti‐tumor proliferation effects of OMM‐15a and their modified ones were detected in MM cell lines ARP1, OCI‐My5 and breast cancer cell line MCF7. The OMM‐15a was transfected into these cells. At the different time point after the transfection (24 hrs, 48 hrs and 72 hrs), the cell proliferation and apoptosis was detected. The quantitative real‐time PCR and western blot were performed to detect the down‐stream signaling pathway of miR‐15a. Results: Our data indicated that the native form of OMM‐15a could work as hsa‐miR‐15a, but its function was weak and short duration. It could only downregulate part of the target genes expression of hsa‐miR‐15a, PHF19 and BCL2. Only PHF19 in one (ARP1) of the 3 cell lines was downregulated in the protein level at the 24 hrs point after transfection. It could not suppress tumor cells proliferation and increase their apoptosis. However, LNA modification at the both ends of the native form OMM‐15a could increase the stability and the function of OMM‐15 and prolonged their anti‐tumor effects. After modification, VEGFA were downregulated in addition to PHF19 and BCL2. And what's more, the proteins of PHF19 and BCL2 were all downregulated in all the 3 cell lines. Moreover, the LNA‐OMM‐15a showed significant effects on suppression of the tumor cells proliferation and on promotion of cells apoptosis. Summary/Conclusion: Treatment with LNA‐OMM‐15a significantly inhibited the proliferation of tumor cells. Cell apoptosis were up‐regulated notably in MM and other tumor cells. This preclinical study indicates that the LNA‐OMM‐15a would be work as a potential effective agent for tumor treatment.