Background: The aim of our study was to determine the role of sphingolipids, which control proliferation and apoptosis, in the placenta of pregnant women with pregnancy-associated breast cancer (PABC) after chemotherapy compared with healthy patients. Methods: We analyzed (by the PCR method) the gene expression of key sphingolipid metabolism enzymes (sphingomyelinases (SMPD1 and SMPD3), acid ceramidase (ASAH1), ceramide synthases (CERS 1–6), sphingosine kinase1 (SPHK1), sphingosine-1-phosphate lyase 1 (SGPL1), and sphingosine-1-phosphate receptors (S1PR1, S1PR2, and S1PR3)) and the content of subspecies of ceramides, sphingosine, and sphingosine-1-phosphate in seven patients with PABC after chemotherapy and eight healthy pregnant women as a control group. Results: We found a significant increase in the expression of genes of acid ceramidase (ASAH1), sphingosine-1-phosphate lyase 1 (SGPL1), sphingosine kinase (SPHK1), and ceramide synthases (CERS 1-3, 5, 6) in the samples of patients with PABC during their treatment with cytostatic chemotherapy. The increase in the expression of the enzymes’ genes was not accompanied by changes in the content of the studied sphingolipids. Such significant changes in the expression of genes controlling the level of CER, sphingosine, and S1P may indicate their ability to initiate the metabolism of pro-apoptotic and anti-apoptotic sphingolipids in the placenta of pregnant women with cancer undergoing chemotherapy in order to maintain levels typical of the placenta of healthy women. Conclusions: Our results may indicate the promising mechanism of placenta protection during chemotherapy for pregnant women with breast cancer and, consequently, of the newborn. This protective effect of the placenta and especially for the newborn has been discovered for the first time and requires more careful study.

This article represents the first consideration of the peculiarities of the fatty acid (FAs) composition and structure of storage triacylglycerols (TAGs) of the relict plant Lunaria rediviva L. The composition of storage TAGs was found to comprise 21 individual FAs, with an unsaturated FA content of 96.8%. Additionally, monounsaturated acids with a very long chain (VLCFAs), specifically C20:1–C24:1, constituted over 60% of the total FAs. The ethylene bond position isomers of unsaturated FAs were accurately identified and the presence of unusual isomers, including 20:1$\Delta$13, 22:1$\Delta$15, and 24:1$\Delta$17 acids. Furthermore, the unusual minor 24:2$\Delta$15,18 acid was identified and characterised for the first time. The pathways of the mentioned VLCFA’s biosynthesis have been proposed. The distribution of FA acyls between the sn positions of triacylglycerols was found to be highly specific. Thus, VLCFAs exclusively acylate the $\alpha$ positions of the carbon atoms of the glycerol residue of the TAG molecule (sn-1 and sn-3 positions), while unsaturated C18 acids exclusively acylate the $\beta$-carbon atom (sn-2 position). The composition of the molecular species of TAGs was analysed using a calculation method based on the Vander Wal model and by RP-HPLC-ESI-MS. A significant discrepancy from the statistical model was observed, indicating a preference for the formation of symmetrical TAGs, such as sn-1,3-dierucoyl-2-oleoyl-glycerol and related molecular species. This observation led to the formulation of a hypothesis regarding the potential existence of at least two specialised enzyme isoforms involved in the biosynthesis of such TAGs via the Kennedy pathway, exhibiting unusual substrate specificity. Consequently, this plant can be regarded not only as a producer of unusual molecular types of triacylglycerols but also as a source of genetic material for the search of genes encoding the aforementioned enzymes with unusual substrate specificity.