Inhibition of angiogenesis and intrahepatic growth of colon cancer by TAC-101.

We demonstrated in this study that inhibition of intra-hepatic growth of colon cancer by TAC-101 is mediated by inhibition of angiogenesis. In vitro experiments showed that TAC-101 inhibited the proliferation of murine hepatic sinusoidal endothelial (HSE) cells induced by coculture with murine colon 26-L5 (L5) cells. HSE cell proliferation was also enhanced by conditioned medium of L5 cells (CM-L5), and this enhancement of proliferation was abrogated by anti-vascular endothelial growth factor antibody. CM-L5 also induced in vitro tube formation of HSE cells on Matri-gel, and this activity of CM-L5 was abrogated by TAC-101 in a concentration-dependent manner. On the other hand, p.o. administration of TAC-101 inhibited tumor-induced angiogenesis in vivo and decreased the weights of L5 tumors in the mouse liver. Reverse transcriptase-PCR analysis using in vivo tumor tissue suggested that repression of vascular endothelial growth factor expression by TAC-101 was associated with the antiangiogenic activity. TAC-101 alone and 5-fluorouracil (5-FU)/D,L-leucovorin (LV) significantly inhibited the intrahepatic growth of L5 tumors (P = 0.002 and 0.001, respectively), whereas 5-FU alone did not (P = 0.088). When TAC-101 was administered with 5-FU/LV, marked enhancement of antitumor activity was observed (95% inhibition; P<0.001). This enhanced antitumor effect was also observed in experiments using Co-3 human colon adenocarcinoma. Concurrent treatment with TAC-101 and 5-FU/LV and sequential treatment with 5-FU/LV followed by TAC-101 resulted in significant augmentation of antitumor activity against Co-3 (overall P = 0.007 and 0.015, respectively). These findings indicate that TAC-101 inhibits tumor angiogenesis and suggest that it may be effective against hepatic metastasis of colon cancer.

Invasiveness of hepatocellular carcinoma cell lines: contribution of membrane-type 1 matrix metalloproteinase.

Intrahepatic metastasis is one of the malignant features of hepatocellular carcinoma (HCC). Matrix metalloproteinases (MMPs) and urokinase-type plasminogen activator (u-PA)/plasmin, are known to be associated with the invasive properties of various types of tumor cells. In this study, we examined which proteinases play a role in the metastatic invasion of human HCC cell lines. JHH-5 and JHH-6 cells constitutively expressed mRNAs for both membrane-type 1 matrix metalloproteinase (MT1-MMP) and u-PA and invaded through reconstituted MATRIGEL in vitro, whereas JHH-7 cells expressed u-PA mRNA but not MT1-MMP and did not invade. However, hepatocyte growth factor (HGF) induced MT1-MMP expression on the surface of JHH-7 cells and markedly increased invasiveness of JHH-7 in a concentration-dependent manner. Moreover, cleavage activity for pro-MMP-2 was induced in HGF-treated JHH-7 cells. MMP inhibitor, rather than serine proteinase inhibitor, potently inhibited HCC cell invasion. Intrahepatic injection of HCC cell lines into athymic nude mice caused visible intrahepatic metastases in vivo. Moreover, JHH-7 tumors showed expression of MT1-MMP mRNA, while in vitro cultured JHH-7 cells did not. These findings suggest that MT1-MMP plays an important role in the invasive properties of HCC cells, and that HGF modifies the invasive properties of noninvasive HCC cells.

4-[3,5-Bis(trimethylsilyl)benzamido] benzoic acid (TAC-101) inhibits the intrahepatic spread of hepatocellular carcinoma and prolongs the life-span of tumor-bearing animals.

We examined the in vivo anti-tumor activity of the benzoic acid derivative, TAC-101 (4-[3,5-bis(trimethylsilyl)benzamido] benzoic acid), for intrahepatic spread of JHH-7 human hepatocellular carcinoma (HCC) cells and its mechanism of action. Oral administration of TAC-101 markedly inhibited liver tumor of JHH-7 cells and prolonged the life-span of tumor-bearing mice without affecting the body weight. The life-prolonging effect of TAC-101 was more effective than that of other anti-cancer agents including CDDP, 5-FU, and CPT-11 (T/C (%) of life-span; 181 to 219, 128, 133, and 142%, respectively). In vitro, TAC-101 at the concentration of more than 10 microM showed direct cytotoxicity against JHH-7 cells caused by induction of apoptosis. Hepatocyte growth factor (HGF) enhanced the invasive ability of JHH-7 cells without affecting the cell viability. Non-cytotoxic concentrations of TAC-101 inhibited the JHH-7 invasion induced by HGF and down-regulated the expression of c-MET protein in a concentration-dependent manner. In summary, these results suggest that TAC-101 would be useful for a new class of therapeutic agents and that it may improve the prognosis of patients with liver-tumors including metastasizing tumor and HCC.

Effect of 4-[3,5-bis(trimethylsilyl)benzamido] benzoic acid (TAC-101) on the liver metastasis of colon 26-L5 carcinoma cells.

We found that oral administration of the benzoic acid derivative, TAC-101 ¿4-[3,5-bis(trimethylsilyl)benzamido] benzoic acid¿ significantly inhibited experimental liver metastasis of murine colon 26-L5 carcinoma cells, whereas all-trans-retinoic acid (ATRA) did not show any inhibitory effect. Treatment with more than 10 microM TAC-101 for 24 h showed direct cytotoxicity against tumor cells in vitro. In contrast, ATRA did not have any direct cytotoxicity. TAC-101 also inhibited the tumor cell invasion enhanced by TPA (12-O-tetradecanoylphorbol-13-acetate; AP-1 activator) in a concentration-dependent manner, whereas ATRA did not. Furthermore, zymographic analysis revealed that noncytotoxic concentrations (< 10 microM) of TAC-101 inhibited TPA-induced production of urokinase-type plasminogen activator (u-PA) and matrix metalloproteinase (MMP)-9 from tumor cells, which is considered to be associated with their invasive and metastatic potentials. These results suggest that such an inhibitory effect is partly due to the ability of TAC-101 to bind a retinoic acid receptor (RAR)-alpha and consequently inhibit metastasis-related gene transcription by interfering with AP-1/DNA binding, as we showed previously. On the other hand, TAC-101 also inhibited the production of MMP-2, which is not affected by TPA. Therefore, the antimetastatic effect of TAC-101 includes an alternative regulatory mechanism for MMP production. These results indicate that the in vivo antimetastatic effect of TAC-101 is partly due to the cytotoxicity against tumor cells, which may be caused by the induction of apoptosis, and inhibition of the production of invasion-associated proteolytic enzymes.

Anti-metastatic and immunomodulating properties of the water extract from Celosia argentea seeds.

We have investigated the anti-metastatic effect of Celosia argentea seed extracts (CAE), which have traditionally been used as a therapeutic drug for eye and hepatic diseases in China and Japan. Intraperitoneal (i.p.) administration of CAE for 7 d before tumor inoculation significantly inhibited liver metastasis caused by intraportal injection of colon 26-L5 carcinoma cells in a dose-dependent manner. CAE also showed concentration dependent mitogenic activity on BALB/c whole splenocytes, whereas incubation of the non-adherent fraction of splenocytes with CAE did not induce this activity. CAE has the ability to induce interleukin (IL)-12 production from macrophages in vitro. Following i.p. administration of CAE the maximal levels of IL-12 and interferon (IFN)-gamma production in serum were achieved at 2-3 and 6 h, respectively. Experiments using macrophage- or NK cell-deficient mice revealed that CAE-induced IL-12 in serum was not mediated by macrophages and that IFN-gamma production was mainly dependent on natural killer (NK) cells. Since CAE was inactive when the contributions of macrophages were removed in our system, its inhibitory mechanism is likely to be mainly associated with the activation of macrophages to an anti-metastatic state rather than NK cells. CAE administration resulted in increased production of IL-2, IFN-gamma and decreased production of a Th2 cytokine (IL-4) from splenocytes stimulated by PMA and A23187. Thus, the anti-metastatic effect by CAE is based on its immunomodulating properties including induction of cytokines such as IL-12, IL-2 and IFN-gamma leading to a Th1 dominant immune state and activating macrophages to the tumoricidal state. This may provide a basis for the inhibition of cancer metastasis.

Oral administration of a Kampo (Japanese herbal) medicine Juzen-taiho-to inhibits liver metastasis of colon 26-L5 carcinoma cells.

We have investigated the inhibitory effect of oral administration of Juzen-taiho-to, a Kampo Japanese herbal medicine, on liver metastasis by the inoculation of a liver-metastatic variant (L5) of murine colon 26 carcinoma cells into the portal vein. Oral administration of Juzen-taiho-to for 7 days before tumor inoculation resulted in dose-dependent inhibition of liver tumor colonies and significant enhancement of survival rate as compared with the untreated control, without side effects. We also found that liver metastasis of L5 cells was enhanced in BALB/c mice pretreated with anti-asialo GM1 serum or 2-chloroadenosine, and in BALB/c nu/nu mice, compared to normal mice. This indicates that NK cells, macrophages, and T-cells play important roles in the prevention of metastasis of tumor cells. Juzen-taiho-to significantly inhibited the experimental liver metastasis of colon 26-L5 cells in mice pretreated with anti-asialo GM1 serum and untreated normal mice, whereas it did not inhibit metastasis in 2-chloroadenosine-pretreated mice or T-cell-deficient nude mice. Oral administration of Juzen-taiho-to activated peritoneal exudate macrophages (PEM) to become cytostatic against the tumor cells. These results show that oral administration of Juzen-taiho-to inhibited liver metastasis of colon 26-L5 cells, possibly through a mechanism mediated by the activation of macrophages and/or T-cells in the host immune system. Thus, Juzen-taiho-to may be efficacious for the prevention of cancer metastasis.