Cudrania tricupidata Bureau (CTB) Glycoprotein Inhibits Proliferation by Di(2-ethylhexyl) phthalate in Primary Splenocytes: Responses in Cell Proliferation Signaling

Abstract

The aim of the present study was to evaluate inhibitory effect of CTB glycoprotein isolated from Cudrania tricuspidata Bureau on DEHP-induced cell proliferation in lymphocytes. Our results revealed that DEHP increased lymphocyte proliferation as confirmed by increasing [³H]thymidine incorporation, and proliferating cell nuclear antigen (PCNA), cyclin D1, and cyclin-dependent kinase (CDK)-4 expression. This was accompanied by induced intracellular Ca²⁺ level, protein kinase C (PKC) translocation from cytosol to membrane, ERK1/2 phosphorylation, and nuclear factor (NF)-κB transcriptional activation in DEHP-treated cells. However, CTB glycoprotein (100 μg/ml) reduced labeled thymidine incorporation and PCNA expression in DEHP-treated cells. Additionally CTB glycoprotein reduced Ca²⁺ level, PKC translocation, ERK1/2 phosphorylation, NF-κB transcriptional activation, cell cycle proteins (cyclin D1 and CDK4) expression in cells. The activation of NF-κB was collectively blocked by pretreatment with PKC inhibitor (staurosporine) and ERK1/2 inhibitor (PD98059), respectively. The results from these experiments indicate that CTB glycoprotein inhibits cell proliferation via down regulations of Ca²⁺/PKC, ERK1/2, and cell cycle proteins induced by DEHP. Therefore, we suggest that the CTB glycoprotein might be one component for prevention of cell proliferation-related immune diseases.

Keywords:

• Cudrania tricuspidata Bureau (CTB) glycoprotein
• Di (2-ethylhexyl) phthalate
• PKC
• Lymphocyte proliferation

ACKNOWLEDGMENT

This work was partially supported by Biotechnology Research Institute, Chonnam National University in 2010.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.