Effect Of ATRA Combined With IFN-α On The Growth Of Multiple Myeloma Cells And Expressions Of GRIM-19 And STAT3

ATRA and IFN are frequently used for hematology malignant tumors, they perform their effect mainly through inducing the tumor cell to apoptosis and differentiate. But, a new research showed that a combination of IFN-βand RA can induce cell death in several cancer cell lines. A few genes that possibly are involved in this process have been identified and named as GRIM (genes associated with retinoid±IFN-induced mortality). GRIM-19 is a member of GRIM'S family. It codes for a novel protein with a Mr- 16 kDa. GRIM-19 homologues are present in most multicellular organisms. IFN/RA-treatment induced the expression of GRIM-19 mRNA and protein. IFN-weakly induced the mRNA, which was enhanced by the presence of RA. Several research indicate that GRIM-19's tumor suppressor functions appear to be modulated through an inactivation of one known oncogenic protein, that is, STAT3. GRIM-19 inhibits transcription driven by activation of STAT3,. Mutational analysis indicates that the transactivation domain of STAT3, especially residue S727, is required for GRIM-19 binding.Multiple myeloma (MM) is characterized by the accumulation of malignant plasmal cells in the bone marrowproducing a monoclonal immunoglobulin. It occupies 10% of all kinds of hematology malignant tumors. The standard conventional therapy is chemotherapy and autollogous stem cell transplantation. The response rate of traditional chemotherapy is 40-60%, complete response rate is lower than 5%, and median survival time is approximately less than 3 years. At the same time, many patients cannot accept stem cell transplantation for several reasons. So we need to search for more effective drug to treat MM.We take human multiple myeloma cell lines 8226 as our study object, to watch the growth inhibiting effect of ATRA combined with IFN, and screen the best drug dose and time, study the mechanism of their synergistic effect. Thus to provide the experiment evidence for searching for more effective drug to treat MM.8226 cells were treated with ATRA in combination or not with INF-αin vitro. Cell proliferation was evaluated by MTT assay. The results showed that the proliferation of 8226 cell line was significantly inhibited by the combination of ATRA and IFN. Statistical significance was also observed in the combined groups compared with the control groups.The semi-quantitative RT-PCR was used to examine the gene expression level of GRIM19. The results showed that the expression of GRIM19mRNA was significantly enhanced in combined groups. Statistical significance was also observed in the combined groups compared with the control groups.GRIM-19 and STAT3 protein expression was determined by Western blot. the result showed that GRIM-19 protein expression was increased but STAT3 protein expression was decreased after ATRA plus IFN-αtreatment (P <0.05).According to our research result, we can draw our conclusion that:1. ATRA in combination with INF-αsuppressed the proliferation of 8226 cells synergistically. 2.ATRA in combination with INF-αcan upregulate GRIM-19 gene expression 3. ATRA in combination with INF-αcan upregulate of GRIM-19 protein expression and down- regulate of STAT3 expression .