CORELATION BETWEEN HEPATIC SINUSOIDAL ENDOTHELIAL CELLS AND HUMAN COLORECTAL CARCINOMA CELLS IN LIVER METASTASIS

The liver is the major site for metastasis by colorectal carcinoma(CRC)and may have different mechanisms that inhibit CRC growth.We have used a tumor cell-sinusoidal endothelial cell(SEC)coculture system to evaluate whether SEC are cytotoxic to weakly or highly metastatic CRC cells.SEC were isolated from the livers of normal Swiss mice by a portal vein enzymatic infusion method and established as monolayers in96well microtiter plates.Confluent SEC monolayers contained93%endothelial cells(by low density lipoprotein(LDL)receptor staining)and 7%Kupffer cells。When CRC cells were prelabeled with the vital fluorescent dyes rhodamine-dextran and calcein AM and then cocultured with confluent SEC monolayers to assess viability，the%metabolic activity of Clone A cells，a weakly metastatic CRC，was significantly lower than that of CX-1cells，a highly metastatic CRC，after4hrs of coculture(p&lt；0.05)。Pretreatment of SEC gadolinium chloride(GaCl I D 23核D2)，an inhibitor of Kupffer cell function，did not block the effect of SEC on Clone A cell.After 24hrs of coculture with Clone A，SEC produced 114±5.0 nM nitrite vs 123±5.0 and 8±2.0 for SEC and Clone A cells cultured alone，respectively.Furthermore，when 10 I D1-6 I D1 to 1 mM N I D 1 G I D 1-methyl-L-arginine(NMMA)was added to SEC and Clone A cocultures，toxicity to Clone A cells was blocked as nitrite production was inhibited by dose greater than 10 I D1-2 ii D1 mM。Unstimulated murine SEC are more toxic to the weakly metastatic Clone A cells than highly metastatic CX-1cells.Thus，hepatic SEC may be a major host effector cell population that eliminates weakly metastatic CRC through the production of nitric oxide.

The liver is the major site for metastasis by colorectal carcinoma (CRC) and may have different mechanisms that inhibit CRC growth. We have used a tumor cell-sinusoidal endothelial cell (SEC) coculture system to evaluate whether SEC are cytotoxic to weakly or highly metastatic CRC cells. SEC were isolated from the livers of normal Swiss mice by a portal vein enzymatic infusion method and established as monolayers in 96 well microtiter plates. Confluent SEC monolayers contained 93% endothelial cells (by low density lipoprotein (LDL) receptor staining) and 7% Kupffer cells. When CRC cells were prelabeled with the vital fluorescent dyes rhodamine-dextran and calcein AM and then cocultured with confluent SEC monolayers to assess viability, the % metabolic activity of Clone A cells, a weakly metastatic CRC, was significantly lower than that of CX-1 cells, a highly metastatic CRC, after 4 hrs of coculture (p<0.05). Pretreatment of SEC gadolinium chloride (GaClィイD23ィエD2), an inhibitor of Kupffer cell function, did not block the effect of SEC on Clone A cell. After 24 hrs of coculture with Clone A, SEC produced 114±5.0 nM nitrite vs 123±5.0 and 8±2.0 for SEC and Clone A cells cultured alone, respectively. Furthermore, when 10ィイD1-6ィエD1 to 1 mM NィイD1GィエD1-methyl-L-arginine (NMMA) was added to SEC and Clone A cocultures, toxicity to Clone A cells was blocked as nitrite production was inhibited by dose greater than 10ィイD1-2ィエD1 mM. Unstimulated murine SEC are more toxic to the weakly metastatic Clone A cells than highly metastatic CX-1 cells. Thus, hepatic SEC may be a major host effector cell population that eliminates weakly metastatic CRC through the production of nitric oxide.