Effect of GnT-V knockdown on the proliferation, migration and invasion of the SMMC7721/R human hepatocellular carcinoma drug-resistant cell line.

Hepatocellular carcinoma (HCC) is a commonly occurring malignant tumor, with a high incidence rate. The present study aimed to investigate the effect of knocking down the N­glycosyltransferase­V (GnT­V) protein on the proliferation, migration and invasion of the human HCC drug­resistant cell line, SMMC7721/R. SMMC7721/R cells with GnT­V­knockdown (SMMC­7721/R­GnT­V) were constructed using the method of lentiviral transfection. The expression of GnT­V was assessed using reverse transcription­quantitative polymerase chain reaction (RT­qPCR) and western blotting. Cell proliferation was determined using an MTT assay, and the extent of cellular apoptosis was assessed using flow cytometric analysis. Additionally, the metastatic ability of the cells in vitro was analyzed using cell adhesion and invasion assays. Western blotting was used to investigate the protein expression levels of caspase­3, caspase­9, Bcl­2, Bax, matrix metalloproteinase (MMP)­2 and MMP­9, and RT­qPCR was used to determine the mRNA expression levels of the genes for the breast cancer resistance protein and P­glycoprotein in the SMMC­7721/R cells. Taken together, the results of the present study revealed that the knockdown of GnT­V significantly suppressed the proliferation, migration and invasion (P<0.05) of the SMMC­7721/R cells. Furthermore, the possible mechanism underlying these phenomena may be associated with the induction of mitochondria­mediated apoptosis, inhibition of the degradation of the extracellular matrix and an enhancement of the drug-sensitivity. GnT­V­knockdown may therefore be used to treat drug­resistant HCC in the future.

Interaction of Apolipoprotein Model Peptides with Liposomes: A High Performance Liquid Chromatography Study.

The apparent partition constants of two amphiphilic peptides, Amp1 and Amp2, for partitioning into phosphatidylglycerol/phosphatidylcholine bilayer were measured using size-exclusion high performance liquid chromatograph. The exposed amino groups of vesicle-bound peptides were studied by TNBS assay. It was proposed that their N-terminals were exposed to the aqueous phase, and that the main explanation for the stronger interaction of Amp1 with lipid bilayer compared with Amp2 was its stronger lipid binding ability, though Amp1 was also buried deeper in the lipid membrane. It was also found that the two peptides were polymerized in buffer, with their amino groups almost totally buried within the polymers.

Interaction of the Apolipoprotein A-I Model Peptides with Liposomes.

Two amphiphilic peptides, Amp1 and Amp2, were synthesized according to the sequence of the lipid-binding domain in apolipoprotein. Amp2 has a Val residue substituted for the Lys at the 4th position of Amp1. Intrinsic fluorescence spectra, peptide-induced leakage of calcein-laoded liposomes, quenching of tryptophan fluorescene by iodide and acrylamide, circular dichroism spectra, and measurement of the membrane penetration depth of tryptophan residue with spin-labeled phospholipids indicate unexceptionally that Amp1 interacted more strongly with the lipid bilayer than Amp2. It is proposed that class A amphiphilic alpha-helix is buried in the membrane in such a way that its long axis is oriented parallel to the membrane plane, and the electrostatic interaction between the positively charged residues located at the polar-nonpolar interface of the amphiphilic helix with the negatively charged head groups of phospholipids is important to the lipid affinity of the amphiphilic peptide.

Influence of Lipid Composition on the Interaction of Apolipoprotein Model Peptides with Liposomes.

Two amphiphilic peptides, Ampl and Amp2, were synthesized according to the sequence of the lipid-binding domain in apoliporotein. Amp2 has a Val residue substituted for the Lys at the 4th position of Ampl. Interaction between Ampl / Amp2 and liposomes with different lipid compositions were compared by studying the blue shifts of the intrinsic fluorescence emission maxima, the peptide-induced lipsome leakage and the quenching of tryptophan fluorescence by acrylamide. The influence of temperature on interactions was studied as well. Ampo1 interacted stronger with acidic lipids while Amp2 interacted stronger with zwitterionic lipids. The interaction was reinforced with the increasing extent of lipid unsaturation as well as with the increase of temperature. The lipid unsaturation had amore prominent effect.