The Effects Of Atrial Natriuretic Peptide On The Proliferation Of Myeloma Cells And The Expression Of MiR-21

Objective:1. To observe the effects of Atrial Natriuretic Peptide on the proliferation andthe cell cycle of Myeloma cells (MM1.S).2. To detect the expression of miR-21in MM1.S cells and explore the anticancereffects of ANP and its mechanism.Methods:1. The human MM1.S cell line was incubated conventionally, and the cells inlogarithmic phase were used to perform study.2. CCK-8assay was used to evaluate the effects of ANP on the proliferativeinhibition of MM1.S cells after treated by various concentrations of ANP for24h,48h,72h.3. Flow cytometry was used to analyse the cell cycle of MM1.S cells treated byvarious concentrations of ANP for24h.4. Western blotting was needed to detect whether the natriuretic peptidereceptor-A (NPR-A) and natriuretic peptide receptor-C (NPR-C) were expressedin MM1.S cells.5. qRT-PCR was employed to analyze the mRNA expression levels of miR-21inMM1.S cells before and after treated with various concentrations of ANP for24h.Results:1. ANP could inhibit growth and proliferation of MM1.S cells in a significantlydose-dependent (1.0-100umol/L) manner（P<0.01），and the inhibition was themost obvious after treated with ANP by24hours.2. After the treatment of1.0umol/L,10umol/L,50umol/L and100umol/L ANP onMM1.S cells for24h, percentage of cells in G1phase increased significantlyaccompanying cell cycle arrest in G1phase compared with the control group（P<0.01）, while the percentage of S and G2phase cells decreased（P<0.05）.Significant differences were observed among the four ANP-treated MM1.S cells groups (p<0.05).3. When MM1.S cells were evaluated by Western blots, the NPR-A and NPR-Creceptors were demonstrated to be present.4. After the treatment of1.0umol/L,10umol/L,50umol/L and100umol/L ANP onMM1.S cells for24h, qRT-PCR examination indicated that miR-21wasdownregulated compared with the control group (P <0.05). ANP (1.0-100umol/L)reduced the expression of miR-21by8.6,24.2,37.5and49%respectively.Conclusions:1. ANP has been found to inhibit the proliferation of MM1.S cells in adose-dependent manner, and the inhibitory effect was the most obvious at thetime of24h.2. ANP has the potent to arrest cell cycle of MM1.S cells in G1phase, therebyinhibiting the synthesis of cellular DNA.3. The NPR-A and NPR-C receptors were present on MM1.S cells.4. The anti-tumor effect of ANP in MM1.S cells could be partly ascribed toinhibiting the expression of miR-21.