Overexpression of the alpha v beta 6 integrin in cervical squamous cell carcinoma is a prognostic factor for decreased survival

Abstract

Cervical squamous cell carcinomas are composed histologically of tumour cell islands surrounded by varying amounts of tumour stroma, the amount and composition of which are influenced by local TGF-beta(1). TGF-beta(1) is secreted in an inactive complex with latency-associated peptide (LAP). Both LAP and the extracellular matrix (ECM) protein fibronectin are important ligands for the integrin receptor alpha v beta 6. While alpha v beta 6 is only weakly expressed by normal epithelia, it is up-regulated in different carcinomas where it generally reflects a more aggressive phenotype. In cervical cancer, the expression of alpha v beta 6 has not thus far been investigated. Given the ability of alpha v beta 6 both to activate TGF-beta(1) and to interact with fibronectin, we studied correlations between the expression of these components and disease parameters in a large cohort of cervical cancer specimens. We analysed alpha v beta 6 expression using immunohistochemistry in primary cervical squamous carcinomas of FIGO stage IA to IIB patients and correlated the findings with formerly investigated fibronectin and TGF-beta(1) expression and clinico-pathological parameters. alpha v beta 6 expression was also examined in cervical intra-epithelial neoplasia (CIN) and lymph node metastases. alpha v beta 6 was only weakly expressed in normal epithelium but clearly up-regulated in CIN lesions. In carcinomas, strong expression of alpha v beta 6 in tumour cells correlated with different clinico-pathological parameters and with worse overall and disease-free survival. Furthermore, alpha v beta 6 expression correlated positively with TGF-beta(1) mRNA expression as well as with fibronectin expression. Overexpression of alpha v beta 6 in cervical squamous carcinomas is an unfavourable prognostic factor. This might reflect an increased capacity of alpha v beta 6-expressing tumour cells to migrate in a fibronectin-rich ECM and/or to activate TGF-beta(1) at the tumour/stroma interface, both of which processes may contribute to cervical cancer progression.