ABSTRACT
Balance between pro-tumor and anti-tumor effects may be affected by molecular interactions within tumor microenvironment. On this basis we searched for molecular partners of ADAMTS-12, a secreted metalloprotease that shows both oncogenic and tumor-suppressive effects. Using its spacer region as a bait in a yeast two-hybrid screen, we identified fibulin-2 as a potential ADAMTS-12-interacting protein. Fibulins are components of basement membranes and elastic matrix fibers in connective tissue. Besides this structural function, fibulins also play crucial roles in different biological events, including tumorigenesis. To examine the functional consequences of the ADAMTS-12/fibulin-2 interaction, we performed different in vitro assays using two breast cancer cell lines: the poorly invasive MCF-7 and the highly invasive MDA-MB-231. Overall our data indicate that this interaction promotes anti-tumor effects in breast cancer cells. To assess the in vivo relevance of this interaction, we induced tumors in nude mice using MCF-7 cells expressing both ADAMTS-12 and fibulin-2 that showed a remarkable growth deficiency. Additionally, we also found that ADAMTS-12 may elicit pro-tumor effects in the absence of fibulin-2. Immunohistochemical staining of breast cancer samples allowed the detection of both ADAMTS-12 and fibulin-2 in the connective tissue surrounding tumor area in less aggressive carcinomas. However, both proteins are hardly detected in more aggressive tumors. These data and survival analysis plots of breast cancer patients suggest that concomitant detection of ADAMTS-12 and fibulin-2 could be a good prognosis marker in breast cancer diagnosis.
Subject(s)
ADAM Proteins/metabolism , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Calcium-Binding Proteins/metabolism , Extracellular Matrix Proteins/metabolism , ADAM Proteins/analysis , ADAM Proteins/genetics , ADAMTS Proteins , Animals , Breast Neoplasms/chemistry , Calcium-Binding Proteins/analysis , Calcium-Binding Proteins/genetics , Cell Movement , Cell Proliferation , Extracellular Matrix/metabolism , Extracellular Matrix Proteins/analysis , Extracellular Matrix Proteins/genetics , Female , Humans , Kaplan-Meier Estimate , MCF-7 Cells , Mice , Neoplasm Invasiveness , Prognosis , Spheroids, Cellular , Tumor Burden , Tumor MicroenvironmentABSTRACT
The human fibulin family consists of seven complex extracellular glycoproteins originally characterized as components of elastic fibers in connective tissue. However, beyond its structural role, fibulins are involved in complex biological processes such as cell adhesion, migration or proliferation. Indeed, they have proved to be essential elements in normal physiology, as shown by mouse models lacking these proteins, that evidence several developmental abnormalities and pathological features. Their relevance is also apparent in tumorigenesis, an aspect that has started to be intensely studied. Distinct fibulins are expressed in both tumor and stromal cells and are subjected to multiple expression regulations with either anti or pro-tumor effects. The mechanistic insights that underlie these observations are now commencing to emerge, portraying these proteins as very versatile and active constituents of connective tissue. The aim of this review is to highlight the most relevant connections between fibulins and cancer.
