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Open Access Research article

Transcription factor AP-1 in esophageal squamous cell carcinoma: Alterations in activity and expression during Human Papillomavirus infection

Showket Hussain1, Alok C Bharti1, Irfana Salam2, Mohammad Akbar Bhat3, Mohammad Muzaffar Mir2, Suresh Hedau1, Mushtaq A Siddiqi4, Seemi Farhat Basir5 and Bhudev C Das16*

Author Affiliations

1 Division of Molecular Oncology, Institute of Cytology & Preventive Oncology (ICMR), I-7, Sector-39, Noida, India

2 Department of Clinical Biochemistry, Sher-I-Kashmir Institute of Medical Sciences, Soura, Srinagar, Jammu and Kashmir, India

3 Department of Cardiovascular and Thoracic Surgery, Sher-I-Kashmir Institute of Medical Sciences, Soura, Srinagar, Jammu and Kashmir, India

4 Department of Immunology and Molecular Medicine Sher-I-Kashmir Institute of Medical Sciences, Soura, Srinagar, Jammu and Kashmir, India

5 Department of Biosciences, Jamia Millia Islamai; New Delhi, India

6 Dr. B.R. Ambedkar Research Centre for Biomedical Research (ACBR), University of Delhi (North Campus), Delhi, India

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BMC Cancer 2009, 9:329  doi:10.1186/1471-2407-9-329

Published: 16 September 2009

Abstract

Background

Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths in Jammu and Kashmir (J&K) region of India. A substantial proportion of esophageal carcinoma is associated with infection of high-risk HPV type 16 and HPV18, the oncogenic expression of which is controlled by host cell transcription factor Activator Protein-1 (AP-1). We, therefore, have investigated the role of DNA binding and expression pattern of AP-1 in esophageal cancer with or without HPV infection.

Methods

Seventy five histopathologically-confirmed esophageal cancer and an equal number of corresponding adjacent normal tissue biopsies from Kashmir were analyzed for HPV infection, DNA binding activity and expression of AP-1 family of proteins by PCR, gel shift assay and immunoblotting respectively.

Results

A high DNA binding activity and elevated expression of AP-1 proteins were observed in esophageal cancer, which differed between HPV positive (19%) and HPV negative (81%) carcinomas. While JunB, c-Fos and Fra-1 were the major contributors to AP-1 binding activity in HPV negative cases, Fra-1 was completely absent in HPV16 positive cancers. Comparison of AP-1 family proteins demonstrated high expression of JunD and c-Fos in HPV positive tumors, but interestingly, Fra-1 expression was extremely low or nil in these tumor tissues.

Conclusion

Differential AP-1 binding activity and expression of its specific proteins between HPV - positive and HPV - negative cases indicate that AP-1 may play an important role during HPV-induced esophageal carcinogenesis.