Differential regulation of MMPs by E2F1, Sp1 and NF-kappa B controls the small cell lung cancer invasive phenotype

Abstract

BackgroundE2F1 transcription factor plays a vital role in the regulation of diverse cellular processes including cell proliferation, apoptosis, invasion and metastasis. E2F1 overexpression has been demonstrated in small cell lung cancer (SCLC), and extensive metastasis in early phase is the most important feature of SCLC. In this study, we investigated the involvement of E2F1 in the process of invasion and metastasis in SCLC by regulating the expression of matrix metalloproteinases (MMPs).MethodsImmunohistochemistry was performed to evaluate the expression of E2F1 and MMPs in SCLC samples in a Chinese Han population. The impact of E2F1 on invasion and metastasis was observed by transwell and wound healing experiments with depletion of E2F1 by specific siRNA. The target genes regulated by E2F1 were identified by chromatin immunoprecipitation (ChIP)-to-sequence, and the expressions of target genes were detected by real time PCR and western blotting. The dual luciferase reporter system was performed to analyze the regulatory relationship between E2F1 and MMPs.ResultsE2F1 is an independent and adverse prognosis factor that is highly expressed in SCLC in a Chinese Han population. Knockdown of E2F1 by specific siRNA resulted in the downregulation of migration and invasion in SCLC. The expressions of MMP-9 and −16 in SCLC were higher than other MMPs, and their expressions were most significantly reduced after silencing E2F1. ChIP-to-sequence and promoter-based luciferase analysis demonstrated that E2F1 directly controlled MMP-16 expression via an E2F1 binding motif in the promoter. Although one E2F1 binding site was predicted in the MMP-9 promoter, luciferase analysis indicated that this binding site was not functionally required. Further study demonstrated that E2F1 transcriptionally controlled the expression of Sp1 and p65, which in turn enhanced the MMP-9 promoter activity in SCLC cells. The associations between E2F1, Sp1, p65, and MMP-9 were validated by immunohistochemistry staining in SCLC tumors.ConclusionsE2F1 acts as a transcriptional activator for MMPs and directly enhances MMP transcription by binding to E2F1 binding sequences in the promoter, or indirectly activates MMPs through enhanced Sp1 and NF-kappa B as a consequence of E2F1 activation in SCLC.

E2F-1 targets miR-519d to regulate the expression of the ras homolog gene family member C

“…We also observed that E2F1 increased Bcl-2, cyclin D1, survivin, MMP2, and MMP9 expression in ovarian carcinoma, but did not alter p53 expression. These results are similar to the oncogenic role of E2F1 in small cell lung cancer [28] and clear cell renal cell carcinoma [29], but differ from the suppressive effect of E2F1 in gastric cancer [17–19] and Hodgkin lymphoma [25]. Our findings suggest that E2F1 functions as an oncogene in ovarian carcinoma in part by upregulating Bcl-2, cyclin D1, survivin, MMP2, and MMP9 expression.…”

Sp1 Plays an Important Role in Vascular Calcification Both In Vivo and In Vitro

“…We previously found that Sp1 mediates the antifibrotic effects of miR‐7a/b in angiotensin II–stimulated cardiac fibroblasts by targeting collagen I . Meanwhile, the MMP‐9 expression level was shown to be transcriptionally regulated by Sp1 . MMP‐9 plays a crucial role in elastin degradation, which is highly pro‐calcific.…”

Silencing of gelatinase expression delays myoblast differentiation in vitro

“…Most of such studies focused on cancer cells in which silencing of selected MMP expression resulted in the inhibition of the cell migration and invasion to other tissues (Sun et al, 2008;Tsung et al, 2008;Shen et al, 2012;Tang et al, 2013;Li et al, 2014). Most of such studies focused on cancer cells in which silencing of selected MMP expression resulted in the inhibition of the cell migration and invasion to other tissues (Sun et al, 2008;Tsung et al, 2008;Shen et al, 2012;Tang et al, 2013;Li et al, 2014).…”