Synergistic Inhibitory Effect Of 9-cis Retinoic Acid And 1, 25-Dihydroxy Vitamin D3 On Growth Of Neuroblastoma Cell Line In Vitro

Objective: This study was to investigate the effects of 9-cis retinoic acid(9-cis RA) and 1,25(OH)₂D₃ on growth , differentiation and apoptosis of human neuroblastoma (NB) SK-N-SH cell line in vitro, explore the synergistic effects and molecular mechanismMethods: T The cells were divided into four groups and treated with 9-cis RA, 1,25(OH)₂D₃ alone or in combination.At the desired time following treatment,neuronal cell differentiation was counted by evaluating morphological change;the growth inhibition rate was measured through MTT assay, the cell apoptosis was assayed with a Flow cytometry(FCM),and the expression of RARβmRNA was determined by reverse transcription-polymerasw chain reaction(RT-PCR).Results: 9-cis RA and 1,25(OH)₂D₃, used alone or in combination,inhibited the growth of SK-N-SH cells in a time-dependent manner. The inhibition was more obvious in the combination group than in 9-cis RA group and 1,25(0H)₂D₃ group (P<0.05),and morphological differentiation obvious.It displayed that combination group can significantly improve the NB cell's inhibition ration than medication alone group by MTT determined. Annexin V/7-AAD staining confirmed the significant synergistic effects of the combination on inducing cell apoptosis. RT-PCR found that the expression of RARβmRNA of the combination is great higher than the others groups.Conclusion: The combination of 9-cisRA and 1,25 (OH)₂D₃ can produce significant synergistic inhibitory effect on the growth, differentiation, apoptosis of NB SK-N-SH cells in vitro.It has outstanding therapeutic efficacy in low dose and outstrip used alone significantly.It suggests that its synergistic mechanism could be through an increase of the mRNA expression level of RARβto inhibit tumor growth ,and it also provides a rational basis and guidance for establishing a combination therapeutic approach for clinical use in the treatment of NB.