Aspirin Inhibition of Group VI Phospholipase A2 Induces Synthetic Lethality in AAM Pathway Down-Regulated Gingivobuccal Squamous Carcinoma.

Kshama Pansare,Ranjeeta Dhotre,Bhabani Mohanty,Nilesh Gardi,Ruby Alhans,Priyanka Sahu,Rucha Dugge,Neha Gupta,Poonam Gera,Saili Parab,Pradnya Kowtal,Rajiv Sarin,Pradip Chaudhari,Aafrin M Pettiwala

doi:10.3390/cells11010123

Abstract

Background: To elucidate the role of iPLA2/PLA2G6 in gingivobuccal squamous cell carcinoma (GB-SCC) and to ascertain the synthetic lethality-based chemoprevention role of aspirin in arachidonic acid metabolism (AAM) pathway down-regulated GB-SCC. Methods: The in vitro efficacy of aspirin on GB-SCC cells (ITOC-03 and ITOC-04) was assessed by cell proliferation, colony formation, apoptosis, cell migration, cell cycle assay and RNA-seq, while inhibition of PLA2G6 and AAM pathway components was affirmed by qPCR, Western blot and immunofluorescence staining. The in vivo effect of aspirin was evaluated using NOD-SCID mice xenografts and immunohistochemical analysis. Results: We found that aspirin, which has been reported to act through the COX pathway, is inhibiting PLA2G6, and thereby the COX and LOX components of the AAM pathway. The findings were validated using PLA2G6 siRNA and immunohistochemical marker panel. Moreover, a pronounced effect in ITOC-04 cells and xenografts implied aspirin-induced synthetic lethality in the AAM pathway down-regulated GB-SCC. Conclusions: This study reveals that aspirin induces the anti-tumor effect by a previously unrecognized mechanism of PLA2G6 inhibition. In addition, the effect of aspirin is influenced by the baseline AAM pathway status and could guide precision prevention clinical trials of AAM pathway inhibitors.

Highlights

Gingivobuccal squamous cell carcinoma (GB-SCC) is the most common cancer in Southeast Asia where smokeless tobacco use is highly prevalent
In the arachidonic acid metabolism (AAM) pathway, phospholipids are hydrolyzed by cytosolic phospholipase and intracellular calcium independent phospholipase into arachidonic acid (AA), a 20-carbon unsaturated fatty acid
A significant dose- and time-dependent decrease in cell viability was observed in both ITOC-03 and ITOC-04 cells and the inhibitory effect was significantly higher in the AAM pathway down-regulated ITOC-04 cells (Figure 1A,B and Figure S1A,B)

Summary

Introduction

Gingivobuccal squamous cell carcinoma (GB-SCC) is the most common cancer in Southeast Asia where smokeless tobacco use is highly prevalent. In the arachidonic acid metabolism (AAM) pathway, phospholipids are hydrolyzed by cytosolic phospholipase (cPLA2) and intracellular calcium independent phospholipase (iPLA2) into arachidonic acid (AA), a 20-carbon unsaturated fatty acid. To elucidate the role of iPLA2/PLA2G6 in gingivobuccal squamous cell carcinoma (GB-SCC) and to ascertain the synthetic lethality-based chemoprevention role of aspirin in arachidonic acid metabolism (AAM) pathway down-regulated GB-SCC. Results: We found that aspirin, which has been reported to act through the COX pathway, is inhibiting PLA2G6, and thereby the COX and LOX components of the AAM pathway. A pronounced effect in ITOC-04 cells and xenografts implied aspirin-induced synthetic lethality in the AAM pathway down-regulated GB-SCC. Conclusions: This study reveals that aspirin induces the anti-tumor effect by a previously unrecognized mechanism of PLA2G6 inhibition. The effect of aspirin is influenced by the baseline AAM pathway status and could guide precision prevention clinical trials of AAM pathway inhibitors

Methods

Results

Discussion

Conclusion