Colchicine does not provide a sustained blockage of collagen and plasma protein secretion by rat hepatocytes

Colchicine has been reported to disrupt microtubules and thereby inhibit collagen secretion. Because of this "anti-collagen" activity, colchicine has been suggested for use in the treatment of hepatic fibrosis. Using biochemical and immunohistochemical techniques, our laboratory has identified the hepatocyte as one possible source of collagen in the liver. The present study examined the direct effect of colchicine on collagen secretion by hepatocytes in culture. Parenchymal cells were isolated from the livers of adult rats four days following a two-thirds hepatectomy. Total collagen and the fraction secreted into the medium were quantitated as incorporation of [3H]-proline into bacterial collagenase-sensitive protein. Treatment of the hepatocytes with 100 microM colchicine (2-3 hours) resulted in a substantial inhibition of collagen secretion. However, upon longer exposure of the hepatocytes to the drug (24 hours and 8 days), the inhibitory effect on collagen secretion was abolished. The anti-protein secretion activity of the colchicine in the conditioned medium removed from the hepatocytes was still present as verified by a 2.5 hour fibroblast-collagen secretion bioassay. The secretion of the plasma proteins albumin, fibrinogen and the third component of complement was not altered by the presence of colchicine. We conclude that the hepatocyte is a highly efficient secretory cell, and is not entirely dependent upon microtubules as organelles for protein secretion. Therefore, to the extent that hepatocytes may contribute to the hepatic fibrosis, the therapeutic use of colchicine to block collagen secretion might be expected to have only limited effectiveness.