Suppressed CCL2 expression inhibits the proliferation of leukemia cells via the cell cycle protein Cyclin D1: preliminary in vitro data

S.-Y. Wu, J. Yang, D. Hong, P.-F. Xiao, J. Lu, L. Gao, Y.-X. Hu, M. Wang, X.-J. Shao, C.-Y. Zhou, J.-Q. Li, J. Pan, J. Ling, W.-Y. Gu, R.-H. Chen, S.-Y. Hu

Department of Hematology, Children’s Hospital of Soochow University, Suzhou, Jiangsu, China. hsy139@126.com

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• Hematology

OBJECTIVE: Chemokine (C-C motif) ligand 2 (CCL2) is a member of the CC subfamily, which displays chemotactic activity for monocytes and basophils. This molecule plays a very important role in many solid tumors and shows changes in the bone marrow microenvironment. However, its role in acute myeloid leukaemia (AML) is still unclear.

MATERIALS AND METHODS: In this study, we established a HL-60 cell line with CCL2 knockdown to explore its effect on leukemogenesis. Lentivirus with CCL2-knockdown was successfully constructed after screening effective CCL2 short hairpin RNA (shRNA) sequences and was transfected into HL-60 cells, which was further validated at the mRNA and protein levels by real-time polymerase chain reaction (PCR) and Western blotting, respectively.

RESULTS: Low expression of CCL2 significantly decreased HL-60 cell growth by increasing the cell arrest at G1 phase by 12% more than controls. We applied RNA sequencing technology to discriminate the gene expression profiles between the cells with CCL2 knockdown and the controls, and Cyclin D1 was selected for further experiments as its expression level was significantly downregulated, which was validated at the mRNA and protein levels. Cyclin D1 knockdown experiments showed that the cell proliferation rate was evidently decelerated, and cell cycle analysis also indicated a similar pattern for CCL2.

CONCLUSIONS: Our study revealed that Cyclin D1 is an effector that mediates CCL2’s function in cell proliferation by blocking cells at G1 phase.

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