Hexadecenoic Fatty Acid Positional Isomers and De Novo PUFA Synthesis in Colon Cancer Cells

Abstract

Palmitic acid metabolism involves delta-9 and delta-6 desaturase enzymes forming palmitoleic acid (9cis-16:1; n-7 series) and sapienic acid (6cis-16:1; n-10 series), respectively. The corresponding biological consequences and lipidomic research on these positional monounsaturated fatty acid (MUFA) isomers are under development. Furthermore, sapienic acid can bring to the de novo synthesis of the n-10 polyunsaturated fatty acid (PUFA) sebaleic acid (5cis,8cis-18:2), but such transformations in cancer cells are not known. The model of Caco-2 cell line was used to monitor sapienic acid supplementation (150 and 300 μM) and provide evidence of the formation of n-10 fatty acids as well as their incorporation at levels of membrane phospholipids and triglycerides. Comparison with palmitoleic and palmitic acids evidenced that lipid remodelling was influenced by the type of fatty acid and positional isomer, with an increase of 8cis-18:1, n-10 PUFA and a decrease of saturated fats in case of sapienic acid. Cholesteryl esters were formed only in cases with sapienic acid. Sapienic acid was the less toxic among the tested fatty acids, showing the highest EC50s and inducing death only in 75% of cells at the highest concentration tested. Two-photon fluorescent microscopy with Laurdan as a fluorescent dye provided information on membrane fluidity, highlighting that sapienic acid increases the distribution of fluid regions, probably connected with the formation of 8cis-18:1 and the n-10 PUFA in cell lipidome. Our results bring evidence for MUFA positional isomers and de novo PUFA synthesis for developing lipidomic analysis and cancer research.

Omega-3 Versus Omega-6 Polyunsaturated Fatty Acids in the Prevention and Treatment of Inflammatory Skin Diseases

“…We have mentioned sapienic acid, a product of ∆6-FADS on palmitic acid which has long been attributed to the sebaceous gland. It is important to point out that nowadays, sapienic acid is becoming a new marker for the FAs metabolism [166,167].…”

The n-10 Fatty Acids Family in the Lipidome of Human Prostatic Adenocarcinoma Cell Membranes and Extracellular Vesicles

“…Moreover, sapienic acid formation increases for the delta-9 desaturase inhibition [5] or its reduced transcription, as well as for a decreased presence of linoleic acid, such as in the case of an accelerated beta-oxidation in sebocytes, as thoroughly discussed by Prouty and Pappas [16]. For the first time, we reported sapienic acid in the cell membrane phospholipids of a human cancer cell line (Caco-2) and, upon sapienic supplementation, we identified its metabolism, to 8cis-C18:1 and 5cis, 8cis-C18:2 (sebaleic acid) (see Figure 1) [17]. By using Laurdan two-photon microscopy, we demonstrated the change of fluidity features, comparing supplementations of the two positional isomers, palmitoleic and sapienic acids, to Caco-2 cells [17].…”

“…Cell membrane pellets of PC3 (n = 8) and LNCaP (n = 8), and corresponding PC3-EVs (n = 8) and LNCaP-EVs (n = 8), were first examined for the lipid classes, identifying phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylcholine (PC), together with cholesterol (CHO) and sphingomyelins (SM), by appropriate methods and standard references (Table S1 in the Supplementary Information). Phospholipids (PE, PS, PC) have fatty acid residues, and under known conditions of transesterification, give fatty acid methyl esters (FAME) [12,13,17]. Fatty acids were recognized by appropriate standards and quantified by GC analysis as µg/mL (Table S2 of the Supplementary Information; see Figures S1-S3 in the Supplementary Information as representative examples of GC chromatograms and peak identification).…”

“…For the first time, we reported sapienic acid in the cell membrane phospholipids of a human cancer cell line (Caco-2) and, upon sapienic supplementation, we identified its metabolism, to 8cis-C18:1 and 5cis, 8cis-C18:2 (sebaleic acid) (see Figure 1) [17]. By using Laurdan two-photon microscopy, we demonstrated the change of fluidity features, comparing supplementations of the two positional isomers, palmitoleic and sapienic acids, to Caco-2 cells [17]. Sebaleic acid is a positional isomer of the It is worth noting that a high sapienic/palmitoleic acid ratio was observed only in primary sebocytes undergoing differentiation and lipogenesis (pediatric source), thus becoming similar to adult sebocytes [15].…”

“…Based on these premises, we decided to perform untargeted lipidomic analysis, with specific attention to the n-10 fatty acid series, in two human prostate cancer cell lines with a high and low metastatic potentials, PC3 and LNCaP (PC3: prostate cancer; LNCaP: Prostate Derived From Metastatic Site: Left Supraclavicular Lymph Node) respectively, widely studied for whole-genome sequencing [24], and their released EVs [25]. In the present work, we use analytical detection by GC (gas chromatography) and GC/MS (gas chromatography/mass spectrometry) under known conditions that allow for separation and characterization of positional/geometrical isomers [17]. In parallel, elongation and desaturation enzyme expressions were determined in the two cell lines.…”