Differential effects of sPLA2-GV and GX on cellular proliferation and lipid accumulation in HT29 colon cancer cells

Abstract

Secretory phospholipase A (sPLA) group of enzymes have been shown to hydrolyze phospholipids, among which sPLA Group V (GV) and Group X (GX) exhibit high selectivity towards phosphatidylcholine-rich cellular plasma membranes. The enzymes have recently emerged as key regulators in lipid droplets formation and it is hypothesized that sPLA-GV and GX enhanced cell proliferation and lipid droplet accumulation in colon cancer cells (HT29). In this study, cell viability and lipid droplet accumulation were assessed by Resazurin assay and Oil-Red-O staining. Interestingly, both sPLA-GV and GX enzymes reduced intracellular lipid droplet accumulation and did not significantly affect cell proliferation in HT29 cells. Incubation with varespladib, a pan-inhibitor of sPLA-Group IIA/V/X, further suppressed lipid droplets accumulation in sPLA-GV but have no effects in sPLA-GX-treated cells. Further studies using catalytically inactive sPLA enzymes showed that the enzymes intrinsic catalytic activity is required for the net reduction of lipid accumulation. Meanwhile, inhibition of intracellular phospholipases (iPLA-γ and cPLA-α) unexpectedly enhanced lipid droplet accumulation in both sPLA-GV and GX-treated cells. The findings suggested an interconnected relationship between extracellular and intracellular phospholipases in lipid cycling. Previous studies indicated that sPLA enzymes are linked to cancer development due to their ability to induce release of arachidonic acid and eicosanoids as well as the stimulation of lipid droplet formation. This study showed that the two enzymes work in a distinct manner and they neither confer proliferative advantage nor enhanced the net lipid droplet accumulation in HT29 cells.

Biological Evaluation, Molecular Docking Analyses, and ADME Profiling of Certain New Quinazolinones as Anti-colorectal Agents

“…Recently, colorectal cancer (CRC) has shown a more drastic increase in its incidence and mortality particularly in the younger population worldwide. , Several enzymes have been proposed to contribute to colorectal carcinogenesis, in particular the human secretory phospholipases A 2 : hsPLA 2 -G-IIA, hsPLA 2 -G-V, and hsPLA 2 -G-X. The pro-tumorigenic roles , of these isoforms are attributed to their potency to cleave the sn-2 ester bond of membrane glycerophospholipids, thus releasing the free fatty acid (mainly arachidonic acid, AA) and lysophospholipids. Further, AA is the precursor for the production of pro-inflammatory mediators termed eicosanoids, which comprise leukotrienes (LTs) and prostaglandins (PGs) including PGE2 under the catalytic effects of lipoxygenases (LOXs) and cyclooxygenase enzymes (COX-1 and COX-2), respectively.…”

Secretory Phospholipase A2 Digital Expression Analysis in Colon Adenocarcinoma

“…Because the enzyme acts as a key regulator of lipid droplets formation, another study explored its role in lipid droplet accumulation in colon cancer cell lines. They detected differences in extracellular/intracellular phospholipases, but the exact mechanism of their implication in CA development and progression is still under investigation (17). The involvement of SPLA2 in CA neo-angiogenesis, invasion/metastasis, and deregulated cell proliferation/apoptosis pathways is another target for research.…”

A reliable and reproducible assay for determining the effect of natural product on macrophages lipid uptake and cholesterol efflux: A case study of maslinic acid

“…14. Analyze the stained intracellular lipids in THP-1 macrophages by using ImageJ analysis software [23] . Oil red O staining is a lychrosome and it is commonly used for detection of neutral triglycerides and lipids within cultured cells and tissues [13,26] .…”