The E2 protein of human papillomavirus type 8 increases the expression of matrix metalloproteinase-9 in human keratinocytes and organotypic skin cultures

Abstract

Non-melanoma skin cancer (NMSC) is the most frequent human cancer of Caucasian populations. Although the ultraviolet irradiation is a key contributor to the establishment of this keratinocyte malignancy, the infection by some types of human papillomavirus (HPV) has also been implicated in NMSC development. Cancers occur as a result of a complex series of interactions between the cancer cell and its surrounding matrix. The matrix metalloproteinases (MMPs) play a role in degrading the extracellular matrix. MMP9 is an important gelatinase involved in processes such as cell migration, invasion and metastasis. In this report, we demonstrated by EMSA experiments that the MMP9 promoter contains a binding site for the transcriptional regulator E2 of HPV8. Transient reporter gene assays showed that HPV8-E2 activated the MMP9 promoter in a dose-dependent manner in human epidermal keratinocytes. An E2 transactivation-defective mutant (I73L) as well as a DNA-binding deficient mutant (R433K) demonstrated no activation of the MMP9 promoter, suggesting that both an intact transactivation and DNA-binding domain are required for E2 activation of the MMP9-promoter. The functional role of the E2 binding site within the MMP9 promoter was also confirmed by mutating the E2 binding site. In organotypic cultures of human skin, an overexpression of MMP9 was observed in suprabasal layers of the HPV8 E2-expressing epidermis thus confirming the results of the monolayer cultures. These results demonstrate that the early gene E2 of HPV8 is able to increase the expression of MMP9 by direct activation of the MMP9-promoter.

BRD4 Phosphorylation Regulates HPV E2-Mediated Viral Transcription, Origin Replication, and Cellular MMP-9 Expression

“…Since an E2BS situated in the MMP-9 promoter-proximal region also containing one NFκB and three AP-1 sites (Figure 7D, top drawing) is known to regulate MMP-9 expression (Akgül et al, 2011), we performed ChIP in these three Ker-CT lines to analyze whether BRD4 is implicated in the recruitment of E2, NFκB, and AP-1 to their cognate sites in regulating MMP-9 gene transcription. In proliferating keratinocytes, binding of E2 was detected at its cognate site in region 2, but also in E2BS-devoid regions 1, 3 and 4 (Figure 7D, middle).…”

Involvement of Brd4 in different steps of the papillomavirus life cycle

“…In the presence of E2, MMP-9 expression is increased (Akgul et al, 2011; Behren et al, 2005; Gasparian et al, 2007; Muhlen et al, 2009). However, Behren et al (2005) showed that specific binding of E2 to the −670 bp upstream region of the MMP-9 promotor was not necessary for activation and that transcription was rather mediated through a mechanism involving AP-1 binding.…”

Gelatinase B/MMP-9 in Tumour Pathogenesis and Progression

“…In general, gelatinase B/MMP-9 transcription with few exceptions depends upon the concerted interaction between several transcriptional cis elements and cognate transcription factors, with particular important roles highlighted for AP1 (−79) and NF-κB (−600) elements, with NF-κB and SP1 transcription factors specific determinant for gelatinase B/MMP-9 expression. Recently, a functional binding site for the E2 protein expressed by human oncogenic papilloma virus 8 has been characterised at position −1100 of the human MMP-9 promoter and shown to promote MMP-9 transcription [134]. …”