am-555s and Colonic-Neoplasms

4-[3,5-Bis(trimethylsilyl)benzamido] benzoic acid (TAC-101) is a novel retinobenzoic acid derivative. The chemopreventive effect and the mechanism of action of TAC-101 were investigated using a rat chemical colon carcinogenesis model.. Colon tumors were induced using intra-rectal instillation of N-methyl-N-nitrosourea (MNU) in F344 rats. These rats were divided into five groups, control, high dose (TAC-101 8 mg/kg)-long period (four weeks), high dose-short period (one week), low dose (TAC-101 0.8 mg/kg)-long period and low dose-short period. After the large bowels were resected at 20 weeks, the number of aberrant crypt foci (ACF) and tumors in the colon were counted. Proliferating cell nuclear antigen (PCNA) positive index, apoptotic index (AI) and Fas expression were also evaluated using immunohistochemistry.. The tumor incidence and the tumor number in the high dose-long period group were decreased in comparison to those in the other groups, but not significantly. However, the number of ACF or PCNA positive indices in the high dose-long period group was significantly decreased in comparison to that in the other groups. On the other hand, the AI and the Fas expression pattern in the tumor and the normal appearing mucosa were not changed in any of the groups.. TAC-101 might inhibit MNU induced colon carcinogenesis via a decrease of ACF. The mechanism of this chemoprevention may be related to a reduction in cell proliferation, but is not directly associated with apoptosis.

Topics: Adenocarcinoma; Alkylating Agents; Animals; Apoptosis; Benzoates; Cell Proliferation; Colonic Neoplasms; fas Receptor; Immunoenzyme Techniques; Male; Methylnitrosourea; Proliferating Cell Nuclear Antigen; Rats; Rats, Inbred F344; Trimethylsilyl Compounds

4-[3,5-bis(trimethylsilyl)benzamido] Benzoic acid (TAC-101) has potent antiproliferative, antiangiogenic, and antitumor effects in vitro and in vivo. These effects might be due to TAC-101 binding to retinoic acid receptor alpha (RAR-alpha) and interfering with the binding of activator protein-1 (AP-1) to DNA. However, little is known about the detailed mechanism of TAC-101 function. We investigated the mechanism of the antiangiogenic effect of TAC-101 using a rat hepatic metastatic model in vivo and DLD-1 human colon cancer cells in vitro. Liver metastases were induced by portal injection of RCN-9 rat colonic cancer cells into F344 rats. TAC-101 (8 mg/kg) was orally administered 5 days per week for 4 weeks and then hepatic tumors were immunohistochemically evaluated for microvessel density (MVD) and vascular endothelial growth factor (VEGF). TAC-101 significantly reduced both MVD and VEGF expression. Northern blot analysis and ELISA indicated that TAC-101 efficiently inhibited production of VEGF mRNA and protein in DLD-1 cells in a time- and dose-dependent manner. These findings suggest that TAC-101 may inhibit progression and metastasis in colon cancer by interfering with tumor production of VEGF.

Topics: Angiogenesis Inhibitors; Animals; Benzoates; Cell Line, Tumor; Colonic Neoplasms; Dose-Response Relationship, Drug; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms, Experimental; Neovascularization, Pathologic; Rats; Rats, Inbred F344; Trimethylsilyl Compounds; Vascular Endothelial Growth Factor A

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.

Topics: Adenocarcinoma; Angiogenesis Inhibitors; Animals; Antineoplastic Combined Chemotherapy Protocols; Benzoates; Cell Division; Colonic Neoplasms; Endothelial Growth Factors; Endothelium, Vascular; Female; Fluorouracil; Humans; Leucovorin; Liver Neoplasms; Lymphokines; Male; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Neovascularization, Pathologic; Trimethylsilyl Compounds; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

We examined the anti-tumor effect of a novel benzoic acid derivative, TAC-101 (4-[3,5-bis(trimethylsilyl) benzamide] benzoic acid) on models with liver metastasis. Oral administration of TAC-101 significantly inhibited spontaneous liver metastasis of AZ-521 (human gastric cancer ) by orthotopic implantation to athymic nude mice. It also inhibited both the liver metastasis of AZ-521 induced by intrasplenic injection and the secondary lung metastasis from the liver. In addition, TAC-101 inhibited the proliferation of Co-3 (human colon adenocarcinoma) that formed a single nodule in the liver of athymic nude mice by intrahepatic implantation. The growth inhibitory effect of TAC-101 on AZ-521 experimental liver metastasis was observed when treatment was started on day 7, 14, or 21 which may correspond to the progressive stage of liver metastasis in clinical settings. Multiple administration of TAC-101 (8 mg/kg/day) significantly prolonged survival time of the animals with liver metastasis by intrasplenic injection of AZ-521 (T/C = 230%) and A549 (human lung adenocarcinoma; T/C = 186%). These effects of TAC-101 were stronger than those of 5-FU, CDDP or ATRA. Furthermore, TAC-101 inhibited the binding of AP-1 to DNA on electrophoretic mobility shift assay using nuclear extract of AZ-521 cells, although ATRA did not inhibit. These findings suggested that TAC-101 may be a candidate for a new class of anti-cancer agents for liver metastasis.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Benzoates; Cell Division; Cell Nucleus; Colonic Neoplasms; DNA-Binding Proteins; Drug Administration Schedule; Gastrointestinal Neoplasms; Humans; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation; Neoplasms, Experimental; Splenic Neoplasms; Survival Analysis; Transcription Factor AP-1; Trimethylsilyl Compounds; Tumor Cells, Cultured

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.

Topics: Animals; Anticarcinogenic Agents; Antineoplastic Agents; Apoptosis; Benzoates; Collagenases; Colonic Neoplasms; Female; Gelatinases; Liver Neoplasms, Experimental; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Metalloendopeptidases; Mice; Mice, Inbred BALB C; Neoplasm Invasiveness; Neoplasm Transplantation; Tretinoin; Trimethylsilyl Compounds; Tumor Cells, Cultured; Urokinase-Type Plasminogen Activator