| Background:Multiple myeloma(MM)is one of the most common malignancies in the blood system and is a malignant clonal proliferative disease of plasma cells.With the aggravation of China’s population aging and the improvement of diagnostic techniques,the incidence of patients with MM shows a significant upward trend,and their long-term survival rate is still not favorable,with the median survival only 3-5years.Although autologous bone marrow transplantation,radiotherapy,chemotherapy,and cellular immunotherapy can improve the prognosis of MM,the MM is still incurable,and elderly patients are generally suffering from adverse reactions caused by chemotherapy.As a result,there is an urgent need to explore effective drugs with low side effects to treat MM.Numerous studies have shown that metformin can play an anti-tumor effect through many mechanisms,but its role in MM is poorly identified.miRNA is a hot molecule involved in tumorigenesis and progression in recent years.Studies,for example,suggest that miR-379 plays a suppressor role in multiple solid tumors,but its role in MM has not been reported.In addition,metformin has been shown to regulate miRNA expression and thus exert anti-tumor effects.Therefore,the aim of our study was to explore on the effect and mechanism of miR-379 on metformin against MM.First,clarifying the biological role of miR-379 in MM and explore the mechanism of its possible regulation MM biological effects.Then,clarifying the role of metformin in MM and explore the molecular mechanism of miR-379 in metformin against MM.This study will provide new ideas for MM treatment and new experimental data for metformin against MM.Methods:We detected the expression levels of miR-379 in normal bone marrow-derived plasma cell n PCs and myeloma cell lines(RPMI-8226,U266 and NCI-H929)using RT-PCR method.The proliferation and apoptosis of myeloma cell line were detected by CCK8 experiment,flow cytometry and Western blot among normal control,miR-379 mimics,and miR-379 inhibitor groups.miR-379 targeted genes were confirmed by bioinformatics and luciferase reporter experiments.In addition,we detected the effect of metformin against MM using clonal formation and transwell experiments in vivo and in vitro.Results:Compared with normal bone marrow-derived plasma cell n PCs,the m RNA expression level of miR-379 significantly decreased in myeloma cell lines.We transfer miR-379 mimics to myeloma cells to further study the biological effects of miR-379 on MM.Compared to the negative controls,the activity and proliferation rate of myeloma cells decreased significantly in miR-379 mimics group,the proportion of G2/M stage and S stage decreased significantly,and the apoptosis rate increased significantly,The expression of cleaved Caspase-3 and Bax protein was significantly increased and the expression of Bcl-2 protein was significantly decreased.These results suggest that miR-379 can inhibit the proliferation of myeloma cells and promote apoptosis.To explore miR-379 possible mechanism of MM,bioinformatics and luciferase reporter experiments showed that YBX1 was a direct target of miR-379.Next,we investigated the role and possible mechanism of metformin against MM.The results showed that metformin inhibited the viability of myeloma cells in a dose-dependent and time-dependent manner and induced apoptosis in myeloma cells in a dose-dependent manner.In addition,the results of human myeloma cell transplantation mouse model suggest that metformin can significantly reduce the volume and weight of transplanted tumor.To further elucidate the mechanism of metformin against MM,metformin intervention in myeloma cells found that metformin can significantly up-regulate miR-379 expression and inhibit YBX1 expression.The rescue experiment(transfection miR-379inhibitor)can partly restore metformin to inhibit the proliferation,invasion and migration of myeloma cells.These results suggest that metformin can play an anti-MM role through regulatory miR-379.Finally,we explored the mechanism of miR-379/YBX1 axis in metformin antiMM.The effect of metformin on the proliferation,migration and invasion of myeloma cells was more significant in si-YBX1 group than in metformin alone.moreover,we found that both metformin intervention and si-YBX1 expression inhibited p-PI3 K and p-Akt expression,and the inhibition was more obvious in Met si-YBX1 group than in the alone intervention group.Therefore,the above results show that metformin regulates PI3K/Akt signaling pathway through the miR-379/YBX1 axis and then plays an anti-MM role.Conclusions :1.miR-379 can inhibit the proliferation of myeloma cells,and promote myeloma cells apoptosis,and thus play an anti-MM role.2.miR-379 plays an anti-MM role through directly regulating YBX1.3.Metformin can play an anti-MM role through the miR-379/YBX1 axis;4.PI3K/Akt signaling pathway is involved in metformin regulation of the miR-379/YBX1 axis. |
