In Vivo Phycocyanin Treatment of S180 Bearing-Mice: Increase in Immunic Function and Inhibition of Tumor Growth.

Objectives: To explore the effect of Phycocyanin (PC), with or without Cyclophosphamide(CY), on the growth inhibition of S180 cells and on the immunity improvement of S180-burdened mice. And to explore the anti-tumor mechanism of Phycocyanin.

Methods: Each 0.2ml of S180 cells, a sarcoma cell line cells, at the concentration of 2×107 cells/ml, were inoculated into the right axilla of each test mouse. These mice were randomizely divided into 4 groups: PC-treated group (including 50−, 75− and 100mg/kg·d- subgroups); CY-treated group (20mg/kg·d); PC plus CY-treated group and normal saline(NS)-treated group which served as control group. 24 hours after the inoculation, PC or CY or PC plus CY or NS, at a final volume of 0.2ml, were injected to the abdominal cavity of each mouse in different group, and consecutively for 7 days. These mice were killed after the seventh treatment, then the peripheral blood, the whole tumor and the spleen were collected from each mouse. Each mouse’s tumor weight was measured and blood routine exam was done. The serum level of IL-2, IFN-γ and TNF-α in each mouse was measured with ELISA method and the result was shown as pg/ml. Spleen cells from each mouse were collected and cultured respectively with ConA for 36 hours, and splenic T lymphocyte proliferation was measured.

Results: PC inhibited the growth of S180 cells at all three tested dosages, 50mg/kg·d, 75mg/kg·d and 100mg/kg·d, and the inhibition rates were 41.41%, 37.37% and 36.36%, respectively. PC-treatment increased WBC counts in PB of tumor-bearing mice. The results also showed that PC-treatment and tumor-bearing situation increased the spleen weight and enhanced the splenic T lymphocyte proliferation induced by ConA. PC-treatment did not reduce the body weight of tumor-bearing mice. Among these three dosage, 50mg/kg·d was shown to have the best effect in the above mentioned parameters, as well as in the increase of IL-2, IFN-γ and TNF-α secretion. PC at dosages of 75mg/kg·d and 100mg/kg·d just increased the serum level of IFN-γ and TNF-α, without the increase of IL-2. Compared with PC-treatment, CY-treatment diminished serum level of IL-2, IFN-γ and TNF-α. PC (75mg/kg·d) combined with CY-treatment increased the tumor inhibition rate to 92.93%.

Conclusions: 1, PC-treatment inhibited the growth of S180 cells. PC plus CY treatment showed more potential effect of growth inhibition. 2, PC enhanced markedly the immune function of S180-bearing mice in terms of increasing the spleen weight and the serum level of IFN-γ and TNF-α, and enhancing T lymphocyte proliferation induced by ConA. Those might account for the anti-tumor mechanism of PC. 3, PC-treatment antagonized the decrease in WBC count induced by CY-treatment. No obvious side effect of PC was found in the present study. Therefore, PC alone or combine with other chemotherapy drugs may offer a new approach in the treatment of hematological malignancies.