Antitumor Activity And Immunomodulatory Effect Of Tachyplesin-Ⅰ From Tachypleus Tridentatus (Chinese Horseshoe Crab)

Tachyplesin-I(T-SS),a cationic peptide consisting of 17 residues,was isolated from acid extracts of horseshoe crab(Tachypleus tridentatus,Chinese horseshoe crab)hemocyte debris.T-SS acts as antimicrobial peptide.It has a strong antimicrobial effect on the growth of Gram-negative R-type bacteria and shows antivirus and antitumor activity.In this study,the character of antitumor activity of T-SS in vivo and in vitro was analyzed.The antitumor immunity activity against sarcoma 180 in mice,immunomodulatory effect in normal and immunosuppressive mice were studied.1.The growth inhibition rate of BEL-7402 cells and Hela cells in vitro in response to T-SS treatment for 48h was determined using MTT method.The cell viability after treatment of T-SS was decreased.The 50%inhibitory concentration of BEL-7402 and Hela cells to T-SS was 6.25μg/ml and 5.26μg/ml respectively.Similarly,the cell inhibition rate of BEL-7402 cells increased gradually with increment of T-SS concentration,from 17.62%at T-SS concentration of 2μg/ml to 62.76%at 10μg/ml.The cell inhibition rates of Hela cells also increased gradually with increment of T-SS concentration from 21.85%at T-SS concentration of 2μg/ml to 65.46%at 8μg/ml,but for a concentration above 8μg/ml,the inhibition rate did not exhibit further increase.2.The antitumor effect and antitumor immunity activity of T-SS were evaluated in Kunmin mice bearing sarcoma S-180 and ascitic fluid-type hepatocarcinoma H-22 implanted tumor.The thymus index and spleen index were counted by immune organ weighting method.The morphology of thymus and spleen were examined under light microscope.The spleen T lymphocyte reproductive activity induced by Con A was detected by MTT method.Carbon clearance test was used to analysis the phagocytosis of monocytes.White blood cell count was calculated with cytometry.T-SS given by intraperitoneal injection significantly inhibited the growth of S-180 solid tumor,and the inhibition rate reached to 67.8%at 0.15mg/kg.However,the inhibition rate decreased with the increment of T-SS concentration.Furthermore,it seems that T-SS may promote the immune function of the mice bearing sarcoma 180. T-SS can markedly prolong the survival time of mice bearing ascitic fluid-type hepatocarcinoma H-22.Similarly,the rate of life prolongation decreased with the increment of T-SS concentration.3.An immunosuppressive animal model induced by cyclophosphamide in mice was established to estimate the immunomodulatory effect of T-SS.In addition,normal mice were used to analyse the effect.The methods used in the evaluation of antitumor and antitumor immunity activity of T-SS in vivo analyzing the effect the antitumor immunity activity were used here.Although T-SS revealed immunomodulatory effect overall at the dose of 0.15mg/kg and 0.6mg/kg on normal and immunosuppressive mice,the immune function could not get back to normal levels at the dose of 0.6mg/kg.Above all,T-SS showed some inhibitive effect on BEL-7402 and Hela tumor cells in vitro,living murine S-180 and H-22 cells in vivo,and its mechanism may be related to the increase of immune function and to the cytotoxic effect.The immunomodulatory effect of T-SS on normal and immunosuppressive mice may testify this.T-SS showed antitumor activity, antitumor immunity activity and immuomodulatory effect.