Protein Disulphide Isomerase A1 Is Involved in the Regulation of Breast Cancer Cell Adhesion and Transmigration via Lung Microvascular Endothelial Cells

Abstract

Cancer cell cross-talk with the host endothelium plays a crucial role in metastasis, but the underlying mechanisms are still not fully understood. We studied the involvement of protein disulphide isomerase A1 (PDIA1) in human breast cancer cell (MCF-7 and MDA-MB-231) adhesion and transendothelial migration. For comparison, the role of PDIA1 in proliferation, migration, cell cycle and apoptosis was also assessed. Pharmacological inhibitor, bepristat 2a and PDIA1 silencing were used to inhibit PDIA1. Inhibition of PDIA1 by bepristat 2a markedly decreased the adhesion of breast cancer cells to collagen type I, fibronectin and human lung microvascular endothelial cells. Transendothelial migration of breast cancer cells across the endothelial monolayer was also inhibited by bepristat 2a, an effect not associated with changes in ICAM-1 expression or changes in cellular bioenergetics. The silencing of PDIA1 produced less pronounced anti-adhesive effects. However, inhibiting extracellular free thiols by non-penetrating blocker p-chloromercuribenzene sulphonate substantially inhibited adhesion. Using a proteomic approach, we identified that β1 and α2 integrins were the most abundant among all integrins in breast cancer cells as well as in lung microvascular endothelial cells, suggesting that integrins could represent a target for PDIA1. In conclusion, extracellular PDIA1 plays a major role in regulating the adhesion of cancer cells and their transendothelial migration, in addition to regulating cell cycle and caspase 3/7 activation by intracellular PDIA1. PDIA1-dependent regulation of cancer–endothelial cell interactions involves disulphide exchange and most likely integrin activation but is not mediated by the regulation of ICAM-1 expression or changes in cellular bioenergetics in breast cancer or endothelial cells.

Inhibitors of ERp44, PDIA1, and AGR2 induce disulfide-mediated oligomerization of Death Receptors 4 and 5 and cancer cell death

“…Because of the relative structural simplicity of DDA molecules, the mechanisms responsible for their target protein selectivity are of interest. PDIA1 has been investigated as a target for anticancer therapeutics, and PDIA1 inhibitors have established anticancer efficacy in preclinical models [46, 47]. AGR2 contributes to tumor progression by facilitating EGFR disulfide bonding and surface presentation [48].…”

Roles of Protein Disulfide Isomerase in Breast Cancer

“…Extracellular PDIA1 enhances the adhesion and migration of breast cancer cells (MCF-7 and MDA-MB-231) by potentially activating β integrins through thiol switches [78]. Also, PDIA1 increases cancer cell adhesion to the endothelial monolayer and collagen type I rather than PDIA3 [78]. The function of AGR2 to promote metastasis is demonstrated in a rat model of overexpressing AGR2 by enhancing the adhesive property of the cells [92].…”

“…However, it is also involved in lobuloalveolar development due to its ability to stimulate cell proliferation [77]. In the recent proteomic study reported by Stojak et al, PDIA1 is identified as a major isoform of PDIs present in human breast cancer cells (MDA-MB-231 and MCF-7) [78]. PDIA3 (ERp57) is found to be the second most abundant isoform in both cell lines.…”

“…Multiple lines of evidence corroborate the involvement of specific PDIs in the process of breast cancer invasion and metastasis. Extracellular PDIA1 enhances the adhesion and migration of breast cancer cells (MCF-7 and MDA-MB-231) by potentially activating β integrins through thiol switches [78]. Also, PDIA1 increases cancer cell adhesion to the endothelial monolayer and collagen type I rather than PDIA3 [78].…”

“…PDIs localized in the endoplasmic reticulum are involved in UPR pathways that determine cell survival or cell death through redox regulation of UPR stress receptors such as IRE1 [57], PERK [57], or ATF6 [62], and regulation of ERAD and autophagy. PDIs located at the cell surface are involved in cell adhesion and migration as evidenced in breast cancer [78,93,95] or glioblastoma [138,150]. Inhibition of extracellular PDIs could impair cell adhesion and migration by inhibiting the activation of metallo-proteases and integrins.…”