Cytosolic Phospholipase A2 Alpha Regulates TLR Signaling and Migration in Metastatic 4T1 Cells

Abstract

Metastatic disease is the leading cause of death in breast cancer patients. Disrupting the cancer cell’s ability to migrate may be a strategy for hindering metastasis. Cytosolic phospholipase A2 α (cPLA2α), along with downstream proinflammatory and promigratory metabolites, has been implicated in several aspects of tumorigenesis, as well as metastasis, in various types of cancer. In this study, we aim to characterize the response to reduced cPLA2α activity in metastatic versus non-metastatic cells. We employ an isogenic murine cell line pair displaying metastatic (4T1) and non-metastatic (67NR) phenotype to investigate the role of cPLA2α on migration. Furthermore, we elucidate the effect of reduced cPLA2α activity on global gene expression in the metastatic cell line. Enzyme inhibition is achieved by using a competitive pharmacological inhibitor, cPLA2α inhibitor X (CIX). Our data show that 4T1 expresses significantly higher cPLA2α levels as compared to 67NR, and the two cell lines show different sensitivity to the CIX treatment with regards to metabolism and proliferation. Inhibition of cPLA2α at nontoxic concentrations attenuates migration of highly metastatic 4T1 cells, but not non-metastatic 67NR cells. Gene expression analysis indicates that processes such as interferon type I (IFN-I) signaling and cell cycle regulation are key processes regulated by cPLA2a in metastatic 4T1 cells, supporting the findings from the biological assays. This study demonstrates that two isogenic cancer cell lines with different metastatic potential respond differently to reduced cPLA2α activity. In conclusion, we argue that cPLA2α is a potential therapeutic target in cancer and that enzyme inhibition may inhibit metastasis through an anti-migratory mechanism, possibly involving Toll-like receptor signaling and type I interferons.

The Quantitative Proteomics Analysis in Glioblastoma After HULC Silencing

“…Phospholipase can hydrolyze membrane phospholipids to arachidonic acid, which is further involved in many Pathological and physiological processes, including inducing in ammation, transmitting signals, and promoting cell growth, etc. Although one study has shown that down expression of PLA2G4A can promote the migration and invasion of esophageal squamous cell carcinoma [24], most researchers considered that PLA2G4A was an oncogene [25][26][27], which was consistent with our results. The data showed that the expression level of PLA2G4A notably decrease after HULC silencing.…”

Ceramide Kinase Is Upregulated in Metastatic Breast Cancer Cells and Contributes to Migration and Invasion by Activation of PI 3-Kinase and Akt

“…The cPLA 2 is another intracellular target of C1P, which, upon C1P binding, is activated to release arachidonic acid and thereby increases prostaglandin E 2 (PGE 2 ) formation [32]. Chronic inflammation is a well-known risk factor for cancer development and, in view of our previous findings that the metastatic sublines 4175 and 1833 produce much higher amounts of PGE 2 [26] and that cPLA 2 is implicated in breast cancer cell migration [35,36], it is plausible that the pro-migratory effect of CerK/C1P involves cPLA 2 . However, in our breast cancer model, neither inhibition of CerK with NVP-231 nor CerK knockdown could attenuate PGE 2 formation ( Figure S10), thus excluding the notion that high PGE 2 production in metastatic cells is due to enhanced C1P production by CerK.…”

Arachidonic Acid Attenuates Cell Proliferation, Migration and Viability by a Mechanism Independent on Calcium Entry

“…Cytosolic phospholipase A 2 (PLA 2 ) degrades membrane phospholipids to generate AA and lysophosphatidic acid [23]. Interestingly, PLA 2 was also reported to be overexpressed in certain cancer cell lines, particularly in the murine breast cancer cell line 4T1 [24] and in basal breast cancer cell lines of human origin such as in MDA-MB-231 and SKBR3 [25][26][27].…”