Identification of Receptor Ligands in Apo B100 Reveals Potential Functional Domains

Tetra-cationic platinum(II) porphyrins like a candidate photosensitizers to bind, selective and drug delivery for metastatic melanoma

Photodynamic therapy (PDT) is an expanding treatment modality due to its minimally invasive localized activity and few adverse effects. This therapy requires photosensitive compounds, which have high sensitivity to light exposure. Thus, in this work, the in vitro antitumor activity of meso-tetra(3- and 4-pyridyl)porphyrins (3-TPyP and 4-TPyP) in metastatic melanoma cell (WM1366 line) and non-tumoral Ovarian lineage Chinese Hamister (CHO) was evaluated using photodynamic process. Cell viability tests, molecular docking, annexin V, confocal microscopy and qRT-PCR were performed. Our results show that both porphyrins inhibited the viability of metastatic melanoma cells when exposed to light and did not alter viability in the dark. In addition, they did not demonstrate cytotoxicity in non-tumor cells. Molecular coupling demonstrated platinum porphyrin affinity for the N-terminal region of APO B-100, LDL receptor, and therefore of the cells under study. Genes such as Caspase 3 and 9, P21, Bax / BCL2, MnSod and GSH showed increased expression. For meta isomer 3-PtTPyP treatment, caspase-9 and caspase-3 expression levels showed a 4.89 and 3.23-fold increase, respectively, while for the para isomer 4-PtTPyP, this change was 3.77 and 12.16-fold, respectively. We also observed an upregulated expression of p21, a protein well-known by its action in cell cycle arrest in a p53-dependent manner. Conclusion: 3-PtTPyP and 4-PtTPyP demonstrated antitumor effect on WM1366 cells, inducing apoptosis and significant alteration of cell cytoskeleton actin. Our work shows that platinum(II) porphyrins may be promising photosensitizers for the treatment of metastatic melanoma by PDT.

Could ornithine supplementation be beneficial to prevent the formation of pro-atherogenic carbamylated low-density lipoprotein (c-LDL) particles?

Carbamylation (or carbamoylation) is a non-enzymatic post-translational modification process of lysine residues and protein N-termini, which occurs throughout the lifespan of both various plasma proteins and low-density lipoprotein (LDL) particles. Carbamylation results from the binding of isocyanates spontaneously derived from high levels of blood urea, environmental pollutants, nutritional sources and leads to the formation of potentially atherogenic carbamylated-LDL (c-LDL) particles. The carbamylation of LDL apolipoproteins is associated unfavorable downstream effects. Ornithine is a non-proteinogenic amino acid, which plays a central role at the urea cycle function. The primary use of ornithine in supplements is to support athletic performance, liver function and wound recovery. Ornithine is structurally highly similar to lysine, and is only one carbon atom shorter in its side-chain. Therefore, we hypothesize that supplemented ornithine could compete with ε-amino groups of lysine residues found in apolipoproteins of native LDL particles in their binding to isocyanates and decrease c-LDL formation. This issue still remains unresolved in current literature and needs to be elucidated in experimental studies.