Background: CS5931, a novel marine peptide, was extracted and purified from the sea
squirt Ciona savignyi. Our previous studies showed that recombinant CS5931 can significantly inhibit
tumor growth both in vitro and in vivo. However, its molecular targets have not been elucidated.
Methods: The target of the recombinant CS5931 was identified by pull-down/SDS-PAGE/MS approaches
and confirmed by Western blot and surface plasmon resonance analysis. Transwell experiments
were used to detect whether the recombinant CS5931 inhibited cancer migration and invasion
via enolase 1. Dot blotting analysis was used to detect the effect of CS5931 on the interaction of enolase
1 and plasminogen, as well as enolase 1 and uPA/uPAR.
Results: Enolase 1 was identified as the molecular target interacting with the recombinant CS5931.
Transwell experiment showed that the recombinant CS5931 was able to inhibit migration and invasion
of HCT116 cells and enolase 1 overexpression reversed the effects of the recombinant CS5931 on migration
and invasion of cancer cells. Dot blotting analysis revealed that the recombinant CS5931
interfered with the interaction among enolase 1 and plasminogen as well as enolase 1 and uPA/uPAR.
Conclusion: Our present study showed that the recombinant CS5931 could inhibit tumor invasion and
matastasis via interacting with enolase 1, suggesting that the new marine polypeptide CS5931 possesses
the potential to be developed as a novel anticancer agent.