Inhibition of PDIs Downregulates Core LINC Complex Proteins, Promoting the Invasiveness of MDA-MB-231 Breast Cancer Cells in Confined Spaces In Vitro

Young, Natalie; Gui, Zizhao; Mustafa, Suleiman; Papa, Kleopatra; Jessop, Emily; Ruddell, Elizabeth; Bevington, Laura; Quinlan, Roy A.; Benham, Adam M.; Goldberg, Martin W.; Obara, Boguslaw; Karakesisoglou, Iakowos

Abstract

Eukaryotic cells tether the nucleoskeleton to the cytoskeleton via a conserved molecular bridge, called the LINC complex. The core of the LINC complex comprises SUN-domain and KASH-domain proteins that directly associate within the nuclear envelope lumen. Intra- and inter-chain disulphide bonds, along with KASH-domain protein interactions, both contribute to the tertiary and quaternary structure of vertebrate SUN-domain proteins. The significance of these bonds and the role of PDIs (protein disulphide isomerases) in LINC complex biology remains unclear. Reducing and non-reducing SDS-PAGE analyses revealed a prevalence of SUN2 homodimers in non-tumorigenic breast epithelia MCF10A cells, but not in the invasive triple-negative breast cancer MDA-MB-231 cell line. Furthermore, super-resolution microscopy revealed SUN2 staining alterations in MCF10A, but not in MDA-MB-231 nuclei, upon reducing agent exposure. While PDIA1 levels were similar in both cell lines, pharmacological inhibition of PDI activity in MDA-MB-231 cells led to SUN-domain protein down-regulation, as well as Nesprin-2 displacement from the nucleus. This inhibition also caused changes in perinuclear cytoskeletal architecture and lamin downregulation, and increased the invasiveness of PDI-inhibited MDA-MB-231 cells in space-restrictive in vitro environments, compared to untreated cells. These results emphasise the key roles of PDIs in regulating LINC complex biology, cellular architecture, biomechanics, and invasion.

Citation

Young, N., Gui, Z., Mustafa, S., Papa, K., Jessop, E., Ruddell, E., …Karakesisoglou, I. (2024). Inhibition of PDIs Downregulates Core LINC Complex Proteins, Promoting the Invasiveness of MDA-MB-231 Breast Cancer Cells in Confined Spaces In Vitro. Cells, 13(11), Article 906. https://doi.org/10.3390/cells13110906

• Journal Article Type: Article
• Acceptance Date: May 18, 2024
• Online Publication Date: May 24, 2024
• Publication Date: Jun 1, 2024
• Deposit Date: Jun 13, 2024
• Publicly Available Date: Jun 13, 2024
• Journal: Cells
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 13
• Issue: 11
• Article Number: 906
• DOI: https://doi.org/10.3390/cells13110906
• Keywords: intermediate filaments, nucleus, nuclear mechanics, lamin, PDI, SUN2, PACMA31, LINC complex, 16F16, nesprins, SUN1
• Public URL: https://durham-repository.worktribe.com/output/2480477