Evidence for a role of MRCK in mediating HeLa cell elongation induced by the C1 domain ligand HMI-1a3.

Abstract

Diacylglycerol (DAG) is a central mediator of signaling pathways that regulate cell proliferation, survival and apoptosis. Therefore, C1 domain, the DAG binding site within protein kinase C (PKC) and other DAG effector proteins, is considered a potential cancer drug target. Derivatives of 5-(hydroxymethyl)isophthalic acid are a novel group of C1 domain ligands with antiproliferative and differentiation-inducing effects. Our previous work showed that these isophthalate derivatives exhibit antiproliferative and elongation-inducing effects in HeLa human cervical cancer cells. In this study we further characterized the effects of bis(3-trifluoromethylbenzyl) 5-(hydroxymethyl)isophthalate (HMI-1a3) on HeLa cell proliferation and morphology. HMI-1a3-induced cell elongation was accompanied with loss of focal adhesions and actin stress fibers, and exposure to HMI-1a3 induced a prominent relocation of cofilin-1 into the nucleus regardless of cell phenotype. The antiproliferative and morphological responses to HMI-1a3 were not modified by pharmacological inhibition or activation of PKC, or by RNAi knock-down of specific PKC isoforms, suggesting that the effects of HMI-1a3 were not mediated by PKC. Genome-wide gene expression microarray and gene set enrichment analysis suggested that, among others, HMI-1a3 induces changes in small GTPase-mediated signaling pathways. Our experiments revealed that the isophthalates bind also to the C1 domains of β2-chimaerin, protein kinase D (PKD) and myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK), which are potential mediators of small GTPase signaling and cytoskeletal reorganization. Pharmacological inhibition of MRCK, but not that of PKD attenuated HMI-1a3-induced cell elongation, suggesting that MRCK participates in mediating the effects of HMI-1a3 on HeLa cell morphology.

• Authors: Virpi Talman, Gergana Gateva, Marja Ahti, Elina Ekokoski, Pekka Lappalainen, Raimo K Tuominen
• Journal: European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences (Eur J Pharm Sci) Vol. 55 Pg. 46-57 (May 13 2014) ISSN: 1879-0720 [Electronic] Netherlands
• PMID: 24486483 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical References

• CFL1 protein, human
• Cofilin 1
• Phthalic Acids
• Protein Kinase Inhibitors
• bis(3-trifluoromethylbenzyl) 5-(hydroxymethyl)isophthalate
• CDC42BPA protein, human
• protein kinase D
• Myotonin-Protein Kinase
• Protein Serine-Threonine Kinases
• Protein Kinase C

Topics

• Cell Proliferation (drug effects)
• Cell Shape (drug effects)
• Cofilin 1 (metabolism)
• Dose-Response Relationship, Drug
• Focal Adhesions (drug effects, enzymology)
• HeLa Cells
• Humans
• Myotonin-Protein Kinase
• Phenotype
• Phosphorylation
• Phthalic Acids (pharmacology)
• Protein Kinase C (antagonists & inhibitors, genetics, metabolism)
• Protein Kinase Inhibitors (pharmacology)
• Protein Serine-Threonine Kinases (antagonists & inhibitors, genetics, metabolism)
• RNA Interference
• Signal Transduction (drug effects)
• Stress Fibers (drug effects, enzymology)
• Time Factors
• Transfection