Lunasin potentiates the effect of oxaliplatin preventing outgrowth of colon cancer metastasis, binds to α ₅β ₁ integrin and suppresses FAK/ERK/NF-κB signaling

The effect of lunasin on colon cancer metastasis was studied using three human colon cancer cell lines in vitro and a liver metastasis model of colon cancer in vivo. Lunasin bound with α ₅β ₁ integrin and internalized into the nucleus of KM12L4 human colon cancer cells. Lunasin (10μM) inhibited the activation of focal adhesion kinase (FAK) by 28%, 39% and 60% in RKO, HCT-116 and KM12L4 human colon cancer cells, respectively. Lunasin caused an increase in the expression of the inhibitor of kappa B alpha (IκB-α), a decrease in nuclear p50 NF-κB and a reduction in the migration of cancer cells. Lunasin (4mg/kg bw) inhibited metastasis and potentiated the effect of oxaliplatin by reducing the expression of proliferating cell nuclear antigen. Liver metastatic nodules were reduced from 28 (PBS) to 14 (lunasin, P=0.047) while combination of lunasin and oxaliplatin to 5 (P=0.004). The tumor burden was reduced from 0.13 (PBS) to 0.10 (lunasin, P=0.039) to 0.04 (lunasin+oxaliplatin, P<0.0001). Moreover, lunasin potentiated the effect of oxaliplatin in modifying expression of proteins involved in apoptosis and metastasis including Bax, Bcl-2, IKK-α and p-p65. Lunasin inhibited metastasis of human colon cancer cells by direct binding with α ₅β ₁ integrin suppressing FAK/ERK/NF-κB signaling, and potentiated the effect of oxaliplatin in preventing the outgrowth of metastasis.