Artemicapillasins A-N, cytotoxic coumaric acid analogues against hepatic stellate cell LX2 from Artemisia capillaris (Yin-Chen).

Under the guidance of bioassay against HSC-LX2, the EtOH extract and the EtOAc fraction of Artemisia capillaris (Yin-Chen) exhibited cytotoxic activity against HSC-LX2 with inhibitory ratios of 39.7% and 68.7% at the concentration of 400.0 µg/mL. Bioassay-guided investigation of Fr. D (the active fraction) yielded 14 new coumaric acid analogues, artemicapillasins A-N (1-14). The structures of the isolates were elucidated by spectroscopic analyses involving UV, IR, MS, 1D and 2D NMR spectra and ECD calculations. Cytotoxic activity against HSC-LX2 cells of these isolates was performed to reveal that 12 compounds demonstrated cytotoxicity with inhibitory ratios more than 50% at 400 µM. The most active artemicapillasin B (2) gave an IC50 value of 24.5 µM, which was about 7 times more toxic than the positive drug silybin (IC50, 162.3 µM). Importantly, artemicapillasin B (2) showed significant inhibition on the deposition of human collagen type I (Col I), human laminin (HL) and human hyaluronic acid (HA) with IC50 values of 11.0, 14.4 and 13.8 µM, which was about 7, 11 and 5 times more active than silybin. Artemicapillasin B (2) as an interesting antihepatic fibrosis candidate is worth in-depth study.

Laminin-1-derived scrambled peptide AG73T disaggregates laminin-1-induced ovarian cancer cell spheroids and improves the efficacy of cisplatin.

We found previously that the laminin-1-derived synthetic peptide AG73 (LQVQLSIR) promoted ovarian cancer cell metastasis in vivo. We have now studied the role of this metastasis-promoting peptide in vitro using TAC3 ovarian cancer cells, which display anchorage-independent growth and form multicellular spheroids. Our goal is to better understand how this peptide can regulate metastasis in vivo. We found that the exogenous addition of either laminin-1 or peptide AG73 stimulated the formation and growth of the spheroids. Western blot analysis indicated that laminin-1 enhanced the expression of integrin beta1, and that AG73 peptide enhanced expression of syndecan-1 and downstream effectors, including mitogen-activated protein kinase (MAPK) and extracellular signal-related kinase (ERK), and also phosphatidylinositol (PI)-3 kinase/AKT activity signaling. The soluble peptide AG73T, which is a scramble peptide of AG73, was able to disaggregate the laminin-1-induced spheroids. Furthermore, the disaggregated cells were twice as sensitive to cisplatin as the intact spheroids. The AG73T peptide in the presence of laminin-1 suppressed expression of integrin beta1 and its downstream effectors, including MAPK/ERK and PI3/AKT activity signaling. The MEK inhibitor U0126 reduced TAC3 cell growth more effectively in the presence of both laminin-1 and AG73T than in the presence of laminin-1 alone. Inhibition of the PI3-K cascade with LY294002 was also more effective in the presence of laminin-1 and AG73T. The increased sensitivity to cisplatin in the presence of AG73T may be due to the greater bioavailability of the drug to the free-floating cells over the spheroids. These findings suggest a novel function of AG73T in ovarian cancer and help to define mechanisms important in ovarian cancer spheroid formation and spread.

Monoclonal antibodies against the 43,000 Da glycoprotein from Paracoccidioides brasiliensis modulate laminin-mediated fungal adhesion to epithelial cells and pathogenesis.

The surface glycoprotein gp43, a highly immunogenic component of Paracoccidioides brasiliensis, is used in the serodiagnosis of paracoccidioidomycosis (PCM) and has recently been shown to specifically bind the extracellular matrix protein laminin. Binding to laminin induces the increased adhesion of the fungus to epithelial cells; a hamster testicle infection model has shown that the gp43-dependent binding of fungal cells to laminin enhances their pathogenicity in vivo. We report on the production and characterization of 12 monoclonal antibodies against the gp43 that recognize peptide sequences in the molecule detecting at least three different epitopes as well as different isoforms of this antigen. MAbs interfered in the fungal pathogenicity in vivo either by inhibiting or enhancing granuloma formation and tissue destruction. Results suggest that P. brasiliensis propagules may start infection in man by strongly adhering to human lung cells. Thus, laminin-mediated fungal adhesion to human lung carcinoma (A549) cells was much more intense than to Madin-Darby canine kidney cells (MDCK), indicating differences in binding affinity. Subsequent growth of fungi bound to the lung cells could induce the granulomatous inflammatory reaction characteristic of PCM. Both steps are greatly stimulated by laminin binding in infective cells expressing gp43.