Cytosolic phospholipase A2 group IVA (cPLA2α)-deficient mice are resistant to collagen-induced arthritis, suggesting that cPLA2α is an important therapeutic target. Here, the anti-inflammatory effects of the AVX001 and AVX002 cPLA2α inhibitors were investigated. In vitro enzyme activity was assessed by a modified Dole assay. Effects on inhibiting IL-1β-induced release of arachidonic acid (AA) and prostaglandin E2 (PGE2) were measured using SW982 synoviocyte cells. In vivo effects were studied in prophylactic and therapetic murine collagen-induced arthritis models and compared to methotrexate (MTX) and Enbrel, commonly used anti-rheumatic drugs. The in vivo response to treatment was evaluated in terms of the arthritis index (AI), histopathology scores and by plasma levels of PGE2 following 14 and 21 days of treatment. Both cPLA2α inhibitors are potent inhibitors of cPLA2α in vitro. In synoviocytes, AVX001 and AVX002 reduce, but do not block, release of AA or PGE2 synthesis. In both CIA models, the AI and progression of arthritis were significantly lower in the mice treated with AVX001, AVX002, Enbrel and MTX than in non- treated mice. Several histopathology parameters of joint damage were found to be significantly reduced by AVX001 and AVX002 in both prophylactic and therapeutic study modes; namely articular cavity and peripheral tissue inflammatory cell infiltration; capillary and synovial hyperplasia; articular cartilage surface damage; and periostal and endochondral ossification. In comparison, MTX did not significantly improve any histopathology parameters and Enbrel only improved ossification. Finally, as a biomarker of inflammation and as an indication that AVX001 and AVX002 blocked the cPLA2α target, we determined that plasma levels of PGE2 were significantly reduced in response to the AVX inhibitors and MTX, but not Enbrel. AVX001 and AVX002 display potent anti-inflammatory activity and disease-modifying properties in cellular and in vivo models. The in vivo effects of AVX001 and AVX002 were comparable to, or superior, to those of MTX and Enbrel. Taken together, this study suggests that cPLA2α inhibitors AVX001 and AVX002 are promising small molecule disease-modifying anti-rheumatic therapies.

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.

Cytosolic phospholipase A2α (cPLA2α) is the rate-limiting enzyme in releasing arachidonic acid and biosynthesis of its derivative eicosanoids. Thus, the catalytic activity of cPLA2α plays an important role in cellular metabolism in healthy as well as cancer cells. There is mounting evidence suggesting that cPLA2α is an interesting target for cancer treatment; however, it is unclear which cancers are most relevant for further investigation. Here we report the relative expression of cPLA2α in a variety of cancers and cancer cell lines using publicly available datasets. The profiling of a panel of cancer cell lines representing different tissue origins suggests that hematological malignancies are particularly sensitive to the growth inhibitory effect of cPLA2α inhibition. Several hematological cancers and cancer cell lines overexpressed cPLA2α, including multiple myeloma. Multiple myeloma is an incurable hematological cancer of plasma cells in the bone marrow with an emerging requirement of therapeutic approaches. We show here that two cPLA2α inhibitors AVX420 and AVX002, significantly and dose-dependently reduced the viability of multiple myeloma cells and induced apoptosis in vitro. Our findings implicate cPLA2α activity in the survival of multiple myeloma cells and support further studies into cPLA2α as a potential target for treating hematological cancers, including multiple myeloma.