Knockdown of STAiR18, an IL-6/STAT3-induced long noncoding RNA, in INA-6 multiple myeloma cells

STAiR18, an mRNA-like STAT3-induced long noncoding RNA shows ubiquitous expression. RNAi-mediated knockdown of STAiR18 led to a dramatic decrease in INA-6 cell vitality. Furthermore, STAiR18 knockdown reduced the STAT3 RNA and protein levels in these cells, suggesting a positive feedback loop between STAT3 and its target ncRNA STAiR18. Microarray analyses of INA-6 cells after STAiR18 or STAT3 knockdown revealed overlapping changes of transcription patterns indicating a close functional interplay between the two molecules. Taken together, STAiR18 represents a novel noncoding RNA that is likely to play an important role for the oncogenic function of the STAT3 pathway. STAT3- and STAiR18-dependent gene expression in human multiple myeloma cell line INA-6 was measured 40 hours after transfection with either a negative control siRNA, an siRNA to STAT3 or an siRNA to STAiR18. Four independent experiments were performed for each siRNA approach, yielding 12 approaches in total.