Effects And Mechanisms Of Carica Papaya Seed Extract Benzyl Isothiocyanate On Malignant Behavior Of Liver Cancer Cells

Benzyl isothiocyanate (BITC), one of the ITCs, is abundant in the seeds of papaya. It has been shown to induce apoptotic cell death and cell cycle arrest in several different human cancer cell types such as breast cancer cells, bladder cancer cells, prostate cancer cells, ovarian cancer cells, and leukemia cells, what's more, it has been shown to inhibit the invasiveness and migaration of tumor cells. a-fetoprotein(AFP) is synthesized with high specifity in liver cancer cells and it plays important role on the resistance to drug induced apoptosis of HCC.Multiple methods including MTT assay, DAPI staining, flow cytometry(FCM), wound healing, tranwell assay, lipofectin transfection, Western Blot and enzymatic activity assay were used to investigate the effects of BITC on liver cancer cells' malignant behavior and the function of AFP played in it. The results showed as follows:Frist, BITC could inhibit liver cacer cells Bel7402and HLE's proliferation, induce their morphological change, apoptosis and G2/M cell cycle arrest in a dose dependent manner.BITC induced apoptosis of Bel7402and HLE cells by promoting caspase-3enzymatic activity and inhibiting the expression of inhibitor of apoptosis protein Survivin; induced HLE cell G2/M cycle arrest by down regulating the expression of Cyclin B1, CDK1, and Cdc25c and upregulating the expression of p21and weel.Second, the inhibitory effects of BITC on cell growth and the induction of apoptosis and G2/M cell cycle arrest could be enhanced by interfering the expression of AFP in Bel7402cell, however, such effects of BITC could be attenuated by overexpressing the expression of AFP in HLE cells. The apoptosis induction effect of BITC could be improved by enhanced caspase-3activity result from the interfering of AFP in Bel7402cell and it could be weakened by reduced caspase-3activity result from the over expressing of AFP in HLE cell. The degree of G2/M cell cycle arrest induced by BITC could be increased by the up regulation of p21and down regulation of CDK1due to the interfering of AFP in Bel7402cell and it could be reduced by the down regulation of p21and up regulation of CDK1due to the overexpressing of AFP in HLE cell.Third, the wound healing, miagaration and invasiveness ability of liver cancer cells Bel7402and HLE could be repressed by BITC via down regulating the expression of MMP-2,-9and CXCR4and inhibiting the the enzymatic activity of MMP-2and MMP-9.Fourth, interfering the expressing of AFP in Bel7402cell could up regulate the expression of PTEN, block the PI3K/AKT signal pathway and further down regulate the expression of MMP-2,-9and CXCR4and further inhibit the the enzymatic activity of MMP-2and MMP-9, which result in the enhancement of inhibitory effect of BITC on the migaration and invasiveness ability in Bel7402cell. On the contary, overexpressing the expressing of AFP in HLE cell could down regulate the expression of PTEN, activate PI3K/AKT signal pathway and up regulate the expression of MMP-2,-9and CXCR4and incresase the enzymatic activity of MMP-2and MMP-9, which resulted in the declinement of inhibitory effect of BITC on the migaration and invasiveness ability in HLE cell.Taken together, our results indicate that BITC could inhibit the maliganant behavior of liver cancer cells and AFP could against this function of BITC; AFP maybe a key molecular of maliganant behavior in liver cancer cells.