Lactoferrin, a protein from bovine milk belonging to the transferring family proteins, contains 2 bound Fe(+3) ions. Recent research has revealed that lactoferrin exhibits not only antimicrobial activity by its high affinity for Fe(+3) but also remarkable anticancer capacity in cancer cell lines. Meanwhile, increasing evidence suggests that aberrant activation of Akt is involved in both normal cells and human cancers and that inhibition of Akt signaling pathway might be a promising strategy for cancer treatment. In the present study, we investigated the effect of the antitumor induced by exposing stomach cancer cell SGC-7901 to lactoferrin for 24 and 48 h. The cell viability was assessed by 3-(4,5)-dimethylthiahiazo(-z-yl)-3,5-di-phenytetrazoliumromide (MTT) assay and apoptosis was quantified by propidium iodide uptake and Annexin V-fluorescein isothiocyanate fluorescent probe label through flow cytometry. Our investigation indicates that inhibitory ratio of 50 microM lactoferrin for proliferation of stomach cancer cell SGC-7901 is much higher than 12.5 and 25 microM, and for the extended treatment time, the concentration of 50 microM has more efficiency than 100 microM lactoferrin. To elucidate a mechanism involved in its antitumor effect, we studied the Akt cell signaling pathway of SGC-7901 while treated by 50 microM of lactoferrin after 0, 24, and 48 h, particularly Akt phosphorylation of 2 individual residues, Ser473 and Thr308, Akt/glycogen synthase kinase-3beta, forkhead in human rhabdomyosarcoma, and nuclear factor-kappaB proteins, respectively, activated by Western blot. The expressions of Akt, phosphorylated Akt Ser473, phosphorylated Akt Thr308, phosphorylated nuclear factor-kappa b p65 Ser536, and Bcl-2 significantly decreased; however, the expressions of phosphorylated glycogen synthase kinase-3beta Ser9, phosphorylated forkhead in human rhabdomyosarcoma Ser256, and phosphorylated caspase-9 Ser196 increased in response to lactoferrin treatment in SGC-7901. These results suggest that lactoferrin inhibits Akt activation and modulates its downstream proteins phosphorylation in apoptosis of SGC-7901 human stomach cancer cells.

The present study investigated the effect of silibinin, the principal potential anti-inflammatory flavonoid contained in silymarin, a mixture of flavonolignans extracted from Silybum marianum seeds, on palmitate-induced insulin resistance in C2C12 myotubes and its potential molecular mechanisms. Silibinin prevented the decrease of insulin-stimulated 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose) uptake and the downregulation of glutamate transporter type 4 (GLUT4) translocation in C2C12 myotubes induced by palmitate. Meanwhile, silibinin suppressed the palmitate-induced decrease of insulin-stimulated Akt Ser473 phosphorylation, which was reversed by wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K). We also found that palmitate downregulated insulin-stimulated Tyr632 phosphorylation of insulin receptor substrate 1 (IRS-1) and up-regulated IRS-1 Ser307 phosphorylation. These effects were rebalanced by silibinin. Considering several serine/threonine kinases reported to phosphorylate IRS-1 at Ser307, treatment with silibinin downregulated the phosphorylation of both c-Jun N-terminal kinase (JNK) and nuclear factor-κB kinase β (IKKβ), which was increased by palmitate in C2C12 myotubes mediating inflammatory status, whereas the phosphorylation of PKC-θ was not significantly modulated by silibinin. Collectively, the results indicated that silibinin prevented inhibition of the IRS-1/PI3K/Akt pathway, thus ameliorating palmitate-induced insulin resistance in C2C12 myotubes.