Background:

C-phycocyanin is a water-soluble protein pigment which is also widely used as an excellent nutrient supplement for human beings.

For the combination experiments, when cells treated with All-trans retinoic acid (ATRA) combined with C-phycocyanin, the IC50 value is lower than that in ATRA group. But under the same IC50, the more C-phycocyanin is used, the less ATRA is needed. Results demonstrate that C-phycocyanin combined with ATRA can significantly decrease CDK-4 mRNA level (P<0.05). The combination index (CI) value of the C-phycocyanin+ATRA combination group is 0.852 which is less than 1, indicating that the two drugs are synergetic under the action concentration (88 μg/L C-phycocyanin+0.102 mM ATRA). Compare with control group, the Integrated optical density (IOD) in C-phycocyanin or ATRA treated group is increased, and the differences are statistically significant (P<0.05) and the differences are further exaggerated in combination group (P<0.01). The expression of caspase-3 in C-phycocyanin group is more than that in the control group but is similar to that in ATRA group, whereas the expression in combination group is maximum[1].

Compare with control group, the average tumor weights of mice in solely C-phycocyanin or ATRA treatment groups are significantly decreased, and further reduced in C-phycocyanin+ATRA synergy group. Results show that single C-phycocyanin can increase the spleen weight of mice but the effects of ATRA are just opposite. C-phycocyanin can also promote the growth of immune organs in mice and increase the body’s immune function. C-phycocyanin and ATRA alone can significantly inhibit Cyclin D1 expression, and when being combined, the inhibitory effect is more obvious[1].

[1]. Li B, et al. The synergistic antitumor effects of all-trans retinoic acid and C-phycocyanin on the lung cancer A549 cells in vitro and in vivo. Eur J Pharmacol. 2015 Feb 15;749:107-14.