Efficient inhibition of growth of metastatic cancer cells after resection of primary colorectal cancer by soluble Flt-1.

Removal of primary tumors often leads to increases in growth of metastatic tumor cells. Thus, development of an efficient treatment to inhibit the growth of metastatic tumor cells after resection of primary tumors appears to be critical for cancer therapy. Here, we reported that administration of a Chinese medicine Shiquandabutao (SQDBT) after removal of the primary cancer significantly inhibited the growth of metastatic cancer cells in mouse liver. Further analyses showed that the effect of SQDBT resulted from one of its main component, Siwutang (SWT), rather than from another main component, Sijunzitang (SJZT). Moreover, we found that the soluble Flt-1 from SWT neutralized the increased placental growth factor (PLGF) secreted by the metastatic cancer cells after primary cancer resection and subsequently inhibited the cancer neovascularization to suppress the metastatic cancer growth. Thus, our study reveals an essential role of SQDBT in inhibiting the growth of metastatic cancer after removal of primary cancer and further highlights PLGF as a potential target for metastatic cancer treatment.