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Open Access Research

The role of globular heads of the C1q receptor in HPV 16 E2-induced human cervical squamous carcinoma cell apoptosis is associated with p38 MAPK/JNK activation

Ling-juan Gao1, Ping-qing Gu1, Wei Zhao1, Wen-yan Ding1, Xue-qing Zhao1, Shu-yu Guo2 and Tian-ying Zhong1*

Author Affiliations

1 State Key Laboratory of Reproductive Medicine, Department of Clinical Laboratory, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Tianfei Alley, Nanjing Mochou Road, Nanjing, 210004, P.R. China

2 National Center for Epidemiology and Population Health, The Australian National University, Canberra, ACT, 0200, Australia

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Journal of Translational Medicine 2013, 11:118  doi:10.1186/1479-5876-11-118

Published: 8 May 2013

Abstract

Background

Human papillomavirus type 16 (HPV 16) E2 protein is a multifunctional DNA-binding protein. HPV 16 E2 regulates many biological responses, including DNA replication, gene expression, and apoptosis. The purpose of this study was to investigate the relationship among the receptor for globular heads of the human C1q (gC1qR) gene expression, HPV 16 E2 transfection and apoptosis regulation in human cervical squamous carcinoma cells (C33a and SiHa).

Methods

gC1qR expression was examined in C33a and SiHa cells using real-time PCR and Western blot analysis. Apoptosis of C33a and SiHa cells was assessed by flow cytometry. C33a and SiHa cell viability, migration and proliferation were detected using the water-soluble tetrazolium salt (WST-1) assay, a transwell assay and 3H-thymidine incorporation into DNA (3H-TdR), respectively.

Results

C33a and SiHa cells that were transfected with a vector encoding HPV 16 E2 displayed significantly increased gC1qR gene expression and p38 mitogen-activated protein kinase (p38 MAPK)/ c-jun N-terminal kinase (JNK) activation as well as up-regulation of cellular apoptosis, which was abrogated by the addition of gC1qR small interfering RNA (siRNA). Furthermore, the changes in C33a and SiHa cell viability, migration and proliferation that were observed upon HPV 16 E2 transfection were abrogated by SB203580 (a p38 MAPK inhibitor) or SP600125 (a JNK inhibitor) treatment.

Conclusion

These data support a mechanism whereby HPV 16 E2 induces apoptosis by silencing the gC1qR gene or inhibiting p38 MAPK/JNK signalling in cervical squamous cell carcinoma.

Keywords:
Human papillomavirus type 16 (HPV 16) E2; Receptor for the globular heads of the human C1q (gC1qR); Apoptosis; Human cervical squamous carcinoma cells