miR‐3941: A novel microRNA that controls IGBP 1 expression and is associated with malignant progression of lung adenocarcinoma

Immunoglobulin ( CD 79a) binding protein 1 ( IGBP 1) is universally overexpressed in lung adenocarcinoma and exerts an anti‐apoptotic effect by binding to PP 2Ac. However, the molecular mechanism of IGBP 1 overexpression is still unclear. In the present study, we used a micro RNA (mi RNA ) array and TargetScan Human software to detect IGBP 1‐related mi RNA s that regulate IGBP 1 expression. The mi RNA array analysis revealed more than 100 mi RNA s that are dysregulated in early invasive adenocarcinoma. On the other hand, in silico analysis using TargetScan Human revealed 79 mi RNA s that are associated with IGBP 1 protein expression. Among the mi RNA s selected by mi RNA array analysis, six (miR‐34b, miR‐138, miR‐374a, miR‐374b, miR‐1909, miR‐3941) were also included among those selected by TargetScan analysis. Real‐time reverse transcription PCR (real‐time RT ‐ PCR ) showed that the six micro RNA s were downregulated in invasive adenocarcinoma ( IGBP 1+) relative to adjacent normal lung tissue ( IGBP 1−). Among these micro RNA s, only miR‐34b and miR‐3941 depressed luciferase activity by targeting 3′ UTR ‐ IGBP 1 in the luciferase vector. We transfected miR‐34b and miR‐3941 into lung adenocarcinoma cell lines (A549, PC ‐9), and both of them suppressed IGBP 1 expression and cell proliferation. Moreover, the transfected miR‐34b and miR‐3941 induced apoptosis of a lung adenocarcinoma cell line, similarly to the effect of si IGBP 1 RNA . As well as miR‐34b, we found that miR‐3941 targeted IGBP 1 specifically and was able to exclusively downregulate IGBP 1 expression. These findings indicate that suppression of miR‐3941 has an important role in the progression of lung adenocarcinoma at an early stage.