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Open Access Highly Accessed Research article

Benzyl butyl phthalate induces migration, invasion, and angiogenesis of Huh7 hepatocellular carcinoma cells through nongenomic AhR/G-protein signaling

Cheng-Fang Tsai1, Tsung-Hua Hsieh1, Jau-Nan Lee2, Chia-Yi Hsu1, Yu-Chih Wang2, Feng-Jie Lai3, Kung-Kai Kuo4, Hua-Lin Wu567, Eing-Mei Tsai128* and Po-Lin Kuo9*

Author Affiliations

1 Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City 807, Taiwan

2 Department of Obstetrics and Gynecology Kaohsiung Medical University Hospital, Kaohsiung Medical University, No. 100, Zihyou 1st Rd., Sanmin District, Kaohsiung City 807, Taiwan

3 Department of Dermatology, Chi-Mei Medical Center, 901 Chung Hwa Road, Yung Kang City, Tainan 701, Taiwan

4 Division of Hepatobiliary Pancreatic Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

5 Department of Biochemistry and Molecular Biology, National Cheng Kung University, Tainan, Taiwan

6 Cardiovascular Research Center, College of Medicine, National, Cheng Kung University, Tainan, Taiwan

7 Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan

8 Center for Resources, Research and Development, Kaohsiung Medical University, Kaohsiung City 807, Taiwan

9 Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, No. 100, Zihyou 1st Rd., Sanmin District, Kaohsiung, Taiwan

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BMC Cancer 2014, 14:556  doi:10.1186/1471-2407-14-556

Published: 1 August 2014

Abstract

Background

The widespread use of phthalates as plasticizers has raised public health concerns regarding their adverse effects, including an association with cancer. Although animal investigations have suggested an association between phthalate exposure and hepatocellular carcinoma, the mechanisms are unknown.

Methods

The hepatocellular carcinoma cell line Huh7 was treated with benzyl butyl phthalate (BBP), and then analyzed by total internal reflection fluorescence microscopy, confocal microscopy and double immunogold transmission electron microscopy. Following BBP treatment, mRNA levels were measured by RT-PCR, protein levels were measured using western blot, and vascular endothelial growth factor levels were measured by an enzyme-linked immunosorbent assay. Cell migration and invasion assays were evaluated by transwell, and angiogenesis were performed by a tube formation assay. Nude mice were used to investigate metastasis and angiogenesis in vivo.

Results

BBP affected hepatocellular carcinoma progression through the aryl hydrocarbon receptor (AhR) and that benzyl butyl phthalate (BBP) stimulated AhR at the cell surface, which then interacted with G proteins and triggered a downstream signaling cascade. BBP activated AhR through a nongenomic action involving G-protein signaling rather than the classical genomic AhR action. BBP treatment promoted cell migration and invasion in vitro and metastasis in vivo via the AhR/Gβ/PI3K/Akt/NF-κB pathway. In addition, BBP induced both in vitro and in vivo angiogenesis through the AhR/ERK/VEGF pathway.

Conclusions

These findings suggest a novel nongenomic AhR mechanism involving G-protein signaling induced by phthalates, which contributes to tumor progression of hepatocellular carcinoma.

Keywords:
Phthalate; Aryl hydrocarbon receptor; Angiogenesis; Migration; Hepatocellular carcinoma