The lysophosphatidic acid-regulated signal transduction network in ovarian cancer cells and its role in actomyosin dynamics, cell migration and entosis

Kaire Ojasalu; Sonja Lieber; Anna M Sokol; Andrea Nist; Thorsten Stiewe; Imke Bullwinkel; Florian Finkernagel; Silke Reinartz; Sabine Müller-Brüsselbach; Robert Grosse; Johannes Graumann; Rolf Müller

doi:10.7150/thno.81656

The lysophosphatidic acid-regulated signal transduction network in ovarian cancer cells and its role in actomyosin dynamics, cell migration and entosis

Theranostics. 2023 Mar 21;13(6):1921-1948. doi: 10.7150/thno.81656. eCollection 2023.

Authors

Affiliations

¹ Department of Translational Oncology, Center for Tumor Biology and Immunology, Philipps University, Marburg, Germany.
² Biomolecular Mass Spectrometry, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany.
³ Genomics Core Facility, Philipps University, Marburg, Germany.
⁴ Bioinformatics Core Facility, Philipps University, Marburg, Germany.
⁵ Institut for Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs University, Freiburg, Germany.
⁶ Institute for Translational Proteomics, Philipps University, Marburg, Germany.

Abstract

Lysophosphatidic acid (LPA) species accumulate in the ascites of ovarian high-grade serous cancer (HGSC) and are associated with short relapse-free survival. LPA is known to support metastatic spread of cancer cells by activating a multitude of signaling pathways via G-protein-coupled receptors of the LPAR family. Systematic unbiased analyses of the LPA-regulated signal transduction network in ovarian cancer cells have, however, not been reported to date. Methods: LPA-induced signaling pathways were identified by phosphoproteomics of both patient-derived and OVCAR8 cells, RNA sequencing, measurements of intracellular Ca²⁺ and cAMP as well as cell imaging. The function of LPARs and downstream signaling components in migration and entosis were analyzed by selective pharmacological inhibitors and RNA interference. Results: Phosphoproteomic analyses identified > 1100 LPA-regulated sites in > 800 proteins and revealed interconnected LPAR1, ROCK/RAC, PKC/D and ERK pathways to play a prominent role within a comprehensive signaling network. These pathways regulate essential processes, including transcriptional responses, actomyosin dynamics, cell migration and entosis. A critical component of this signaling network is MYPT1, a stimulatory subunit of protein phosphatase 1 (PP1), which in turn is a negative regulator of myosin light chain 2 (MLC2). LPA induces phosphorylation of MYPT1 through ROCK (T853) and PKC/ERK (S507), which is majorly driven by LPAR1. Inhibition of MYPT1, PKC or ERK impedes both LPA-induced cell migration and entosis, while interference with ROCK activity and MLC2 phosphorylation selectively blocks entosis, suggesting that MYPT1 figures in both ROCK/MLC2-dependent and -independent pathways. We finally show a novel pathway governed by LPAR2 and the RAC-GEF DOCK7 to be indispensable for the induction of entosis. Conclusion: We have identified a comprehensive LPA-induced signal transduction network controlling LPA-triggered cytoskeletal changes, cell migration and entosis in HGSC cells. Due to its pivotal role in this network, MYPT1 may represent a promising target for interfering with specific functions of PP1 essential for HGSC progression.

Keywords: DOCK7; MYPT1; entosis; lysophosphatidic acid; migration.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Actomyosin* / metabolism
Cell Movement / physiology
Entosis
Female
Humans
Neoplasm Recurrence, Local
Ovarian Neoplasms* / metabolism
Signal Transduction

Substances

Actomyosin
lysophosphatidic acid