Plasminogen Activator Inhibitor 1 (PAI1) Promotes Actin Cytoskeleton Reorganization and Glycolytic Metabolism in Triple-Negative Breast Cancer

Abstract

Migration and invasion of cancer cells constitute fundamental processes in tumor progression and metastasis. Migratory cancer cells commonly upregulate expression of plasminogen activator inhibitor 1 (PAI1), and PAI1 correlates with poor prognosis in breast cancer. However, mechanisms by which PAI1 promotes migration of cancer cells remain incompletely defined. Here we show that increased PAI1 drives rearrangement of the actin cytoskeleton, mitochondrial fragmentation, and glycolytic metabolism in triple-negative breast cancer (TNBC) cells. In two-dimensional environments, both stable expression of PAI1 and treatment with recombinant PAI1 increased migration, which could be blocked with the specific inhibitor tiplaxtinin. PAI1 also promoted invasion into the extracellular matrix from coculture spheroids with human mammary fibroblasts in fibrin gels. Elevated cellular PAI1 enhanced cytoskeletal features associated with migration, actin-rich migratory structures, and reduced actin stress fibers. In orthotopic tumor xenografts, we discovered that TNBC cells with elevated PAI1 show collagen fibers aligned perpendicular to the tumor margin, an established marker of invasive breast tumors. Further studies revealed that PAI1 activates ERK signaling, a central regulator of motility, and promotes mitochondrial fragmentation. Consistent with known effects of mitochondrial fragmentation on metabolism, fluorescence lifetime imaging microscopy of endogenous NADH showed that PAI1 promotes glycolysis in cell-based assays, orthotopic tumor xenografts, and lung metastases. Together, these data demonstrate for the first time that PAI1 regulates cancer cell metabolism and suggest targeting metabolism to block motility and tumor progression.Implications: We identified a novel mechanism through which cancer cells alter their metabolism to promote tumor progression.

Tumor-secreted PAI-1 promotes breast cancer metastasis via the induction of adipocyte-derived collagen remodeling

“…Moreover, in triple negative breast cancer (TNBC), PAI-1-secreted by TNBC cells could stimulate the expression and secretion of CCL5 from endothelial cells, which then enhanced TNBC cells migration, invasion, and metastasis [44]. Overexpression of PAI-1 in TNBC cells further promoted alignment of collagen perpendicular to the margin of tumor, suggesting PAI-1 might exert roles in surrounding tumor microenvironment in orthotopic breast cancer [48]. Interestingly, our present study indicated breast cancer cells secreted PAI-1 led to the activation of PLOD2 expression in adipocytes microenvironment, while the addition of tiplaxtinin further abrogated PLOD2 activation in CAAs (Fig.…”

The role of collagen in cancer: from bench to bedside

“…MMP-1 COLI Regulated to facilitate melanoma cell growth and invasion [227,228] COLIV Regulated to foster breast cancer cell invasion in response to prolactin [229] MMP-2 COLI Modulating MMP-2 activation in osteosarcoma [230] COL4A2 Modulating MMP-2 activation and activity in liver cancer [231] COLI and COLIV Regulated by the knockdown of MMP-2 to induce cancer metastases [232,233] Collagen organization Regulated to enhance malignant glioma recurrence and resistance to vemurafenib [234,235] MMP carcinoma [166,167]. TACS-3 was shown to be driven by increased plasminogen activator inhibitor 1 via ERK signaling and promoted the migration of triple-negative breast cancer cells [168]. The elevated density and depth of collagen deposition showed high proliferation and invasion of cancer cells [169,170].…”

Enhanced mitochondrial fission suppresses signaling and metastasis in triple-negative breast cancer

“…To identify the activity of ERK and Akt, we used the kinase translocation reporter (KTR) for ERK and Akt as previously described [17,18]. This KTR construct contains H2B fused to mCherry (H2B-mCherry), the Akt-KTR reporter (Aquamarine), the ERK-KTR reporter (mCitrine), and a puromycin selection marker all separated by P2A linker sequences cloned into the Piggyback transposon vector as described previously (pHAEP) [18].…”