mir-155 down regulation by lna inhibitor can reduce cell growth and proliferation in pc12 cell line

micrornas (mirnas) are a class of small non coding regulatory rnas that have key functions in multiple cell processes. deregulation of these tiny mirnas are involved in various human diseases. mir-155 is one of the multifunctional mirna that its over-expression has been found to be associated with different kinds of cancer such as leukemia, breast and colon cancers. it is thought that deregulation and over-expression of this microrna may be associated with pc12 cell proliferation. so, the aim of this study was to investigate the role of mir-155 expression on pc12 cell growth. for this reason, pc12 cells were cultured and transfected by 3 different concentration (25, 50 and 75 nmol) of either lna anti-mir-155 or scramble antisense in 24-well plate. then, total rna was extracted from transfected cells. mirna cdnas were synthesized from isolated total rna. in the second step, mir-155 expression level was analyzed using the quantitative real-time polymerase chain reaction (qrt-pcr). mtt test was performed to evaluate cell viability. in the next step, apoptosis assay was assessed to investigate anti mir-155 effect on pc12 cells death. obtained results were analyzed with t-test. mtt test revealed that cell viability of transfected cells with 75 nm of anti-mir- 155 to be reduced by half of the control and scramble groups (0.5 vs. 0.97 and 0.94). our data suggest that mir-155 over-expression is associated with pc12 cell growth. so, mir-155 down regulation by anti-mir-155 could open up new ways to restrain brain tumor growth, as anti-mir-155 causes pc12 cells to repress.