tachyplesin-peptide--tachypleus-tridentatus and Adenocarcinoma

The importance of the antitumor activity of some antimicrobial peptides (AMPs) is being increasingly recognized. The antimicrobial peptide, tachyplesin, has been shown to exhibit anticancer properties and a linear, cysteine deleted analogue (CDT), was found to retain its antibacterial function.. The objective was to test CDT and related analogues against normal mammalian, bacterial, and cancer cells to determine their effectiveness and then utilize specific assays to determine a possible mechanism of action.. We used sequence reversal and D-amino acids to synthesize four CDT analogues by solid phase peptide synthesis. A number of assays were used including liposome dye-leakage, antibacterial activity against both Gram-positive and Gram-negative bacterial strains, hemolytic assays, methyl thiazolyl tetrazolium (MTT), and apoptosis to examine their effectiveness as both AMPs and anti-cancer peptides (ACPs). We then tested the analogues for their ability to inhibit proliferation of the human lung cancer cell line, A549.. We found that D-CDT exhibited the best bactericidal properties of those tested and was not damaging to red blood cells. Both D-CDT and reverse D-CDT showed a dose-dependent reduction of cell viability. However, D-CDT was most effective with an IC50 of 9.814 μM, a value 9-fold lower than that calculated for reverse D-CDT (90.16 μM). Apoptosis does not appear to be a mechanism by which D-CDT exerts its anticancer properties since > 100 μM was required to increase activation of caspase 3. Moreover, the ERK1/2 pathway is also unlikely since only a modest (20%) decrease of activity was observed with > 100 μM D-CDT. However, D-CDT was found to operate via a hyaluronan (HA)-dependent mechanism as pretreatment of the cells with hyaluronidase decreased the cytotoxic effects of D-CDT on A549 cells and increased its IC50 29-fold to 283.9 μM.. D-CDT is both an effective AMP and ACP, and likely exerts its anticancer effects through both membranolytic as well as an HA-mediated mechanism.

Topics: A549 Cells; Adenocarcinoma; Adenocarcinoma of Lung; Amino Acid Sequence; Amino Acids; Antimicrobial Cationic Peptides; Apoptosis; Cell Proliferation; Cysteine; DNA-Binding Proteins; Drug Screening Assays, Antitumor; Gram-Negative Bacteria; Humans; Lung Neoplasms; MAP Kinase Signaling System; Peptides, Cyclic

To investigate the effects of tachyplesin and n-sodium butyrate on proliferation and gene expression of human gastric adenocarcinoma cell line BGC-823.. Effects of tachyplesin and n-sodium butyrate on proliferation of BGC-823 cells were determined with trypan blue dye exclusion test and HE staining. Effects of tachyplesin and n-sodium butyrate on cell cycle were detected by flow cytometry. Protein levels of c-erbB-2, c-myc, p53 and p16 were examined by immunocytochemistry.. The inhibiting effects were similar after 2.0 mg/L tachyplesin and 2.0 mmol/L n-sodium butyrate treatment, the inhibitory rate of cellular growth was 62.66% and 60.19% respectively, and the respective maximum mitotic index was decreased by 49.35% and 51.69% respectively. Tachyplesin and n-sodium butyrate treatment could markedly increase the proportion of cells at G(0)/G(1) phase and decrease the proportion at S phase. The expression levels of oncogene c-erbB-2, c-myc, and mtp53 proteins were down-regulated while the expression level of tumor suppressor gene p16 protein was up-regulated after the treatment with tachyplesin or n-sodium butyrate. The effects of 1.0 mg/L tachyplesin in combination with 1.0 mmol/L n-sodium butyrate were obviously superior to their individual treatment in changing cell cycle distribution and expression of c-erbB-2, c-myc, mtp53 and p16 protein. The inhibitory rate of cellular growth of BGC-823 cells after combination treatment was 62.29% and the maximum mitotic index was decreased by 51.95%.. Tachyplesin as a differentiation inducer of tumor cells has similar effects as n-sodium butyrate on proliferation of tumor cells, expression of correlative oncogene and tumor suppressor gene. It also has a synergistic effect on differentiation of tumor cells.

Topics: Adenocarcinoma; Antimicrobial Cationic Peptides; Butyrates; Cell Cycle; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p16; DNA-Binding Proteins; Drug Synergism; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Mitotic Index; Peptides, Cyclic; Proto-Oncogene Proteins c-myc; Receptor, ErbB-2; Stomach Neoplasms; Tumor Suppressor Protein p53