Epithelial-to-mesenchymal transition involves triacylglycerol accumulation in DU145 prostate cancer cells

Abstract

aEpithelial to mesenchymal transition (EMT) is a biological process that plays a crucial role in cancer metastasis. Although studies regarding the EMT mechanisms are usual in terms of gene expression and protein functions, little is known about the involvement of lipids in EMT. In this work, an untargeted lipidomic analysis was performed to reveal which lipids are involved in the EMT process. DU145 prostate cancer cells were treated with TNFα, a well-known EMT inducer. After 6 hours of treatment, a decrease of cell membrane E-cadherin as well as a reduction in its gene expression were observed. Also, the mesenchymal markers Vimentin and Snail were up-regulated, suggesting that EMT started below 6 hours of treatment. Lipid extracts of untreated and TNFα-treated cells at short times were analyzed using ultra-performance liquid chromatography coupled to high-resolution mass spectrometry (UPLC-MS). Multivariate data analysis methods were applied to decipher which lipids presented significant changes after EMT induction. Among the results obtained, a significant increase of twelve unsaturated triacylglycerides (TAGs) was observed. This increase of TAGs was also observed for cells treated with TGFβ (another EMT inducer), suggesting that this feature is a common mechanism in the EMT process. In conclusion, this work reported for the first time a TAG accumulation through EMT induction. These TAG lipids could have a key role in providing cells with the energy, cell membrane components and signaling lipids necessary to guarantee the enhanced cell migration and proliferation of metastatic cells.

Targeting the Metabolic Reprogramming That Controls Epithelial-to-Mesenchymal Transition in Aggressive Tumors

“…In addition to the above discussed increase in TAGs, a reduction of C16:0 ceramide levels was also associated with EMT (148, 156). A recent study documented that TGF-β-induced EMT in human breast epithelial cells downregulates the expression of ceramide synthase 6 (CerS6), which produces C16:0 ceramide, further metabolized to C16:0 sphingolipids, such as sphingomyelin and glycosphingolipids, both enriched in the PM microdomains (156).…”

“…A lipidomic approach performed on prostate cancer cells that underwent EMT following TNFα treatment revealed a significant increase in the synthesis of triacylglicerols (TAGs), sustained by a concomitant upregulation of fatty acid synthase (FASN) (148). It is conceivable that the newly synthesized TAGs, stored into LDs, may act not only as a reservoir of energy, but also of fatty acids (FAs), which could serve for protein modification, cell membrane remodeling, and the generation of pro-tumorigenic signals which support EMT-induced cell motility.…”

Phenotypic and lipidomic characterization of primary human epidermal keratinocytes exposed to simulated solar UV radiation

“…After 24 h of each irradiation endpoint, cells were harvested using trypsin, centrifuged at 1300 rpm for 3 min at 4 C and cell pellets were washed twice with cold PBS 1 Â . Two types of extraction were used in this work, one to extract all lipids and another to specifically extract sphingolipids, as previously described [16].…”

“…This method allowed the simultaneous resolution of all the elution and MS spectral profiles of the different sample lipid constituents [24,25]. MCR-ALS has been previously applied for the resolution of the elution and spectral profiles of the constituents of complex sample mixtures analysed by LC-MS and it has been extended more recently to omic studies [16,[26][27][28][29][30][31][32].…”

Discovery of Unexpected Sphingolipids in Almonds and Pistachios with an Innovative Use of Triple Quadrupole Tandem Mass Spectrometry

“…The total lipid extracts were prepared as described elsewhere [9]. Briefly, after the addition of 10 µL of IS (Cer C12, gluCer C12 20 mM), the powder (250 mg) was extracted in a microtube with an O-ring seal screw with 500 µL of methanol, 100 µL water, and 250 µL chloroform [32]. The samples were sonicated for 30 min and incubated overnight in an oscillator bath at 48 • C. The supernatant was evaporated under a stream of nitrogen.…”