Abstract 118: Relationship of MMP11 to Gli1 and prognosis in breast cancer.

Abstract

Abstract Background: Gli1 is a transcription factor and oncogene that was first described in the context of Hedgehog signaling. We have previously shown that nuclear localization of Gli1 is predictive of a poor prognosis in estrogen receptor (ER)-negative (ER-), but not ER-positive (ER+) breast carcinomas (BrCa) [Xu et al. Breast Cancer ResTreat 2010:59]. In addition, we demonstrated that overexpression of Gli1 in ER- BrCa cell lines increases cell migration and invasion and, conversely, silencing of Gli1 decreases migration, invasion and metastasis [Kwon et al. Clinical Exp Metastasis 2011:437]. We also found that MMP11 is a down-stream target of Gli1 that is, at least in part, responsible for the pro-invasive/metastatic activity of Gli1. Methods: To extend these findings, we immunostained a microarray of 140 clinically-annotated BrCa for MMP11 and analyzed the results with regard to expression of Gli1 and prognosis. MMP11 was assessed in cancer epithelial cells and associated stromal cells. To study the function of Gli1 and MMP11 in metastasis, we derived a highly invasive variant of the ER- cell line SUM1315 by serial invasion-selection and compared expression of Gli1 and MMP11 in the parental cells and invasive variant. Results: There was no significant correlation between epithelial expression of MMP11 and nuclear localization of Gli1 (p=0.193, r=0.112) in cancer epithelium. However, stromal expression of MMP11 was positively correlated with nuclear localization of Gli1 in cancer epithelium (p=0.001, r=0.284), possibly due to increased secretion of MMP11 by Gli1-positive (i.e., those with nuclear Gli1) BrCa. In addition, stromal expression of MMP11 was higher in Gli1-positive than Gli1-negative BrCa (p=0.05). By Kaplan-Meier analysis, neither stromal nor epithelial expression of MMP11 alone was predictive of a poorer overall survival when considering all BrCa, ER+ and ER- BrCa. However, in ER- BrCa, high (> mean) epithelial expression of MMP11 and Gli1 nuclear localization identified a group with a particularly poor overall survival (p=0.035, Log-rank test), although Gli1 nuclear localization alone in ER- BrCa was also predictive of a poor overall survival (p=0.014, Log-rank test). By transwell invasion assay, the invasive variant of SUM1315 was approximately 3 times more invasive than parental cells. Expression of Gli1 by quantitative RT-PCR was similar in invasive variant and parental SUM1315, while expression of MMP-11 was 2-fold higher in the invasive variant. Conclusions: Stromal expression of MMP11 was higher in Gli1-positive than Gli-negative BrCa. Yet, expression of MMP11 alone was not a prognostic indicator nor did MMP11 expression improve the prognostic value of Gli1. Expression of MMP11 was modestly elevated in invasive variants of SUM1315. These findings suggest that MMP11 alone is not responsible for the increased invasion and poor prognosis resulting from Gli1 activity in BrCa. Funding provided by Susan G. Komen for the Cure Citation Format: Kun Yuan, Jenny L. Raines, Devanshu D. Kaushik, Andra R. Frost. Relationship of MMP11 to Gli1 and prognosis in breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 118. doi:10.1158/1538-7445.AM2013-118