ABSTRACT
<p><b>AIM</b>To explore the effects of tRNA on the growth of mammalian cells.</p><p><b>METHODS</b>L929, NIH3T3, MCF-7 and PC12 cells were seeded in 96 well culture plate individually, and incubated at 37 degrees C in 5% CO2 for 4 h, the tRNAs from different species were added to the culture media individually. After certain time of incubation, the viability of the cells was evaluated by the MTT methods. Sub-confluent L929 cells were incubated with 200 microg/ml ytRNA for different times, then the cells were pooled and analyzed with flow cytometry assay.</p><p><b>RESULTS</b>tRNA specifically inhibited the growth of L929 cells in a dose-dependent manner. The sizes of tRNA-treated cells showed larger sizes and longer processes than those of untreated cells. Flow cytometric analysis further showed that most of tRNA-treated cells were arrested in S phase of the cell cycle.</p><p><b>CONCLUSION</b>The cell growth inhibitory effects of tRNAs were caused mainly by their degraded fragments. The results suggested that tRNA or its degraded fragments might play important roles in regulation of cell proliferation.</p>