In silico analysis of the binding properties of solasonine to mortalin and p53, and in vitro pharmacological studies of its apoptotic and cytotoxic effects on human HepG2 and Hep3b hepatocellular carcinoma cells

Abstract

Liver cancer, of which human hepatocellular carcinoma (HCC) is the most common type, represents the second most common cause of death from cancer worldwide. To date, treatments remain mostly ineffective and efforts are made to discover new molecules or therapeutic strategies against HCC. Mortalin, an hsp70 chaperone protein, is overexpressed in various cancer, including HCC. Mortalin sequesters p53 into the cytoplasm, thereby inhibiting its translocation to the nucleus and consequently, its cellular functions. Inhibition of mortalin–p53 interactions, which should activate the apoptotic process and the subsequent cell death, has thus been proposed as an anticancer strategy. In silico screening of a database of 354 natural compounds identified solasonine, a steroidal glycoalkaloid from Solanaceae, as a potent inhibitor of p53–mortalin interactions. Pharmacological studies confirmed that solasonine was able to inhibit efficiently mortalin–p53 interaction in HCC HepG2 cell line that expresses both mortalin and p53. This resulted in p53 translocation to the nucleus. Solasonine‐induced apoptosis and cell death of HCC cell lines either expressing p53 (HepG2) or not (Hep3b), indicating that apoptotic activities of solasonine can be mediated not only through p53‐dependent but also p53‐independent pathways. The cytotoxic effects of solasonine correlated in part with its apoptotic properties and differed in the two HCC cell lines, being reversed by pifithrin‐α, an inhibitor of p53 functions, in HepG2 cells but not in Hep3b cells. Nonapoptotic cell death was also observed, notably in Hep3b cells.

In Silico Assessment and Molecular Docking Studies of Some Phyto-Triterpenoid for Potential Disruption of Mortalin-p53 Interaction

“…For the examination, the two known inhibitors including Withanone and Withaferin A were chosen from various studies in the literature. The two inhibitors were docked within the possible p53 binding site of Mortalin in a range of 423 to 597 residues (PDB ID: 3N8E), which include key amino acids Leu450, Ala475, Gln479, Arg513 and Glu 577, respectively [19][20][21]. The docking-simulated region for model PDB ID: 4KBO focus on domain 253-282 with key amino acids Asp136, Asn139, Glu270, Phe272, Asp277 and Arg284, respectively [15,19].…”

“…Compound 21 displayed the best pharmacophore fit scores compared to the others, which formed four H-bonds with Leu450; Glu483; Arg513; Asn583 (Figures 3 and S2). Compound 22 formed 3 hydrogen bonds with key residues: Glu448, Glu483 and Arg513, whereas compound 19 formed two H-bonds with Ser473-both [19,20]. Arg 513, due to its position of the "latch" between the "lid and cleft regions" of mortalin, has been highlighted as the key residue determining the chaperone function of the protein [34].…”

“…Applying Lipinski's Rule of Five and pharmacokinetic parameters in combination with obtained dock score, nine compounds were considered as promising for further drug development including compounds 14, 16, 17, 18, 19, 21, 22, 34 and 38. The stereoview of the binding mode of nine potential inhibitors of protein Mortalin is depicted in Figure S2.It was shown that the occurrence of Mortalin-p53 binding abrogation on Mortalin model 3N8E requires interaction on key amino acid residues, such as Leu450, Ser473, Gln479 and Arg513 at the active site of protein[19,20]. Arg 513, due to its position of the "latch" between the "lid and cleft regions" of mortalin, has been highlighted as the key residue determining the chaperone function of the protein[34].…”

High affinity of 4‐(4‐(dimethylamino)styryl)‐N‐methylpyridinium transport for assessing organic cation drugs in hepatocellular carcinoma cells

“…Human hepatocellular carcinoma cell line derived from HepG2 has been widely used as an in vitro model for drug toxicity screening and the regulation of drug‐metabolizing enzymes due to reproducibility, ease of handling, and commercial availability . Upregulated efflux transporter hABCB1, also known as multidrug resistance protein 1 (MDR1), in hypoxic condition reversed apoptosis induced by doxorubicin in HepG2 cells .…”

Quantitative MALDI-MSI combined with LC-MS/MS metabolomics analysis to study the inhibition of solasonine in lung cancer

“…Most patients are diagnosed with advanced or intermediate stages, and effective treatment options for advanced HCC are limit, so their 5-year survival rate is very low (Park et al, 2015). Pharmacological studies have confirmed (Pham et al, 2019) that solasonine can effectively inhibit the interaction of Hepg2 cells that simultaneously express p53 and mortalin (hsp70 chaperone protein, lethal protein) and activate the apoptotic process. MSI results suggest that the efficacy of solasonine in orthotopic liver lesions may be highly correlated with the high permeability and sustained maintenance of the drug.…”