Decreased expression of the plasminogen activator inhibitor type 1 is involved in degradation of extracellular matrix surrounding cervical cancer stem cells

Abstract

Abstract. The plasminogen activator (PA) system consists of plasminogen activator inhibitor type 1 (PAI-1), urokinase-type plasminogen activator and its receptor (uPA and uPAR). PAI-1 inhibits the activation of uPA (which converts plasminogen to plasmin), and is involved in cancer invasion and metastasis, by remodeling the extracellular matrix (ECM) through regulating plasmin. Cancer stem cells (CSCs) are a small subset of cells within tumors, and are thought to be involved in tumor recurrence and metastasis. Considering these facts, we investigated the relationship between PAI-1 and cervical CSCs. We used ALDH1 as a marker of cervical CSCs. First, we demonstrated that culturing ALDH1-high cells and ALDH-low cells on collagen IV-coted plates increased their expression of active PAI-1 (ELISA), and these increases were suggested to be at mRNA expression levels (RT-qPCR). Secondly, we demonstrated PAI-1 was indeed involved in the ECM maintenance. With gelatin zymography assays, we found that ALDH1-high cells and ALDH-low cells expressed pro-matrix metalloproteinase-2 (pro-MMP-2) irrespective of their coatings. With gelatinase/collagenase assay kit, we confirmed that collagenase activity was increased when ALDH1-low cells were exposed to TM5275, a small molecule inhibitor of PAI-1. Putting the data together, we hypothesized that cancer cells adhered to basal membrane secrete abundant PAI-1, on the other hand, cancer cells (especially CSCs rather than non-CSCs) distant from basal membrane secrete less PAI-1, which makes the ECM surrounding CSCs more susceptible to degradation. Our study could be an explanation of conflicting reports, where some researchers found negative impacts of PAI-1 expression on clinical outcomes and others not, by considering the concept of CSCs.

RRAD, IL4I1, CDKN1A, and SERPINE1 genes are potentially co-regulated by NF-κB and p53 transcription factors in cells exposed to high doses of ionizing radiation

“…Hence, it is important to note that two of them – RRAD [ 40 ] and CDKN1A [ 41 ] were reported to affect the activation of stem cell factors OCT4, NANOG, and SOX2. Moreover, the activity of SERPINE1 was involved in the promotion of the stem cell-like phenotype of cancer cells [ 42 ]. Furthermore, IL4I1 expressed in tumor-associated myeloid cells was involved in immune evasion of cancer cells [ 43 ].…”

Regeneration of cervical reserve cell-like cells from human induced pluripotent stem cells (iPSCs): A new approach to finding targets for cervical cancer stem cell treatment

“…However, we showed a new approach for cervical CSC research, and in that sense, we can conclude that iRCs are potentially useful. Indeed, we focused on the relationship between cervical CSCs and PAI-1 from the cytokine analysis data (Figure 5), and, using the conventional cervical cancer cell lines CaSki and SiHa, we have already shown that PAI-1 plays a role in the maintenance of the extracellular matrix surrounding cervical CSCs [46]. In addition, we found the discrepancies between extracellular HLA-G expression and intracellular HLA-G expression.…”

Prostaglandin E2 receptor 3 (EP3) signaling promotes migration of cervical cancer via urokinase-type plasminogen activator receptor (uPAR)

“…PGE 2 can increase mRNA and protein levels of PAI-1 by binding with EP1/EP3 receptor in rat ventricular fibroblasts, contributing to elevated fibrin deposition in aortic stenosis (Kassem et al 2014 ). However, Sato et al suggested that TM5275 (a small molecular inhibitor of PAI-1) can increase the collagenase activity of SiHa and CaSki cells (Sato et al 2016 ), implying that lower expression of PAI-1 benefits the ECM degration and cervical cancer migration. The latter study was in accordance with our study that silencing EP3 increased the production of PAI-1 and decreased the migration in HeLa and SiHa cells.…”

“…The latter study was in accordance with our study that silencing EP3 increased the production of PAI-1 and decreased the migration in HeLa and SiHa cells. Conflicting effects of PAI-1 on migration might due to the different distances of cervical cancer cells from basal membrane (Sato et al 2016 ).…”

“…Overexpressions of both PAI-1 (Hazelbag et al 2004 ; Horn et al 2002 ) and uPA (Fujishiro et al 1994 ; Sugimura et al 1992 ) are associated with poor prognosis in cervical cancer patients. However, Sato et al proposed that lower levels of PAI-1 are produced in cervical cancer cells that distant from the basal membrane, especially in cervical cancer stem cells (Sato et al 2016 ). These conflicting reports indicate the complex roles of PAI-1 in cervical carcinoma development, which requires further investigations.…”