All-trans retinoic acid arrests cell cycle in leukemic bone marrow stromal cells by increasing intercellular communication through connexin 43-mediated gap junction

Yao Liu,Lei Gao,Jia-Li Li,Shi-Jie Yang,Cheng Zhang,Xing-Hua Chen,Xi Zhang,Kai Wan,Xi-Xi Xiang,Qin Wen,Xue-Lian Chen,Li Gao,Jiang-Fan Zhong

doi:10.1186/s13045-015-0212-7

Abstract

BackgroundGap junctional intercellular communication (GJIC) is typically decreased in malignant tumors. Gap junction is not presented between hematopoietic cells but occurred in bone marrow stromal cells (BMSCs). Connexin 43 (Cx43) is the major gap junction (GJ) protein; our previous study revealed that Cx43 expression and GJIC were decreased in acute leukemic BMSCs. All-trans retinoic acid (ATRA) increases GJIC in a variety of cancer cells and has been used to treat acute promyelocytic leukemia, but the effects of ATRA on leukemic BMSCs is unknown. In this study, we evaluated the potential effects of ATRA on cell cycle, proliferation, and apoptosis of leukemic BMSCs. Effects of ATRA on Cx43 expression and GJIC were also examined.MethodsHuman BMSCs obtained from 25 patients with primary acute leukemia, and 10 normal healthy donors were cultured. Effects of ATRA on cell cycle, cell proliferation, and apoptosis were examined with or without co-treatment with amphotericin-B. Cx43 expression was examined at both the mRNA and protein expression levels. GJIC was examined by using a dye transfer assay and measuring the rate of fluorescence recovery after photobleaching (FRAP).ResultsATRA arrested the cell cycle progression, inhibited cell growth, and increased apoptosis in leukemic BMSCs. Both Cx43 expression and GJIC function were increased by ATRA treatment. Most of the observed effects mediated by ATRA were abolished by amphotericin-B pretreatment.ConclusionsATRA arrests cell cycle progression in leukemic BMSCs, likely due to upregulating Cx43 expression and enhancing GJIC function.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-015-0212-7) contains supplementary material, which is available to authorized users.

Highlights

Gap junctional intercellular communication (GJIC) is typically decreased in malignant tumors
These findings suggested that Connexin 43 (Cx43) expression and GJIC function in bone marrow stromal cells (BMSCs) are likely to be a dynamic process and regulated by many factors in vivo and in vitro
All-trans retinoic acid (ATRA) increases Cx43 mRNA Quantitative reverse transcription polymerase chain reaction analysis showed that treatment with ATRA (10 uM) increased Cx43 mRNA levels in leukemic BMSCs by >50 % (p < 0.01) to a level closed to normal BMSCs (p < 0.05, Fig. 1)

Summary

Introduction

Gap junctional intercellular communication (GJIC) is typically decreased in malignant tumors. Connexin 43 (Cx43) is the major gap junction (GJ) protein; our previous study revealed that Cx43 expression and GJIC were decreased in acute leukemic BMSCs. All-trans retinoic acid (ATRA) increases GJIC in a variety of cancer cells and has been used to treat acute promyelocytic leukemia, but the effects of ATRA on leukemic BMSCs is unknown. Our previous studies revealed decreased Cx43 expression and GJIC function of acute leukemic BMSCs, which could recover after adopting effective chemotherapy or transfection with Cx43 gene [18, 19]. These findings suggested that Cx43 expression and GJIC function in BMSCs are likely to be a dynamic process and regulated by many factors in vivo and in vitro. This hypothesis has been verified by some studies which demonstrated that some hormones, cytokines, and drugs could affect the expression of Cxs between coupling cells [20,21,22,23]

Results

Discussion

Conclusion