Retinoids: effects on growth, differentiation, and nuclear receptor expression in human pancreatic carcinoma cell lines

Abstract

Background & aims: Advanced pancreatic carcinoma has a dismal prognosis despite extensive chemotherapeutic trials. The aim of this study was to evaluate the role of retinoids as an experimental therapeutic approach for pancreatic cancer.

Methods: Four ductal and one acinar pancreatic tumor cell lines were investigated. Growth was determined by cell number and a human tumor clonogenic assay. In vivo growth was assessed by xenografts transplanted into nude mice. Differentiation was characterized by immunofluorescence microscopy and carbonic anhydrase II gene expression. Retinoid receptors were characterized by Northern blotting and reverse-transcriptase polymerase chain reaction.

Results: Retinoid treatment results in a time- and dose-dependent growth inhibition in vitro and in vivo of ductal but not acinar pancreatic tumor cells. Retinoid treatment induces a more differentiated phenotype in ductal tumor cells as shown by morphological criteria and increased expression of carbonic anhydrase II. All pancreatic tumor cell lines expressed a broad panel of cellular retinoid binding proteins and nuclear retinoid receptors. Retinoic acid receptor gamma and cellular retinoic acid binding protein II were found in all retinoid-sensitive ductal tumor cell lines but not in the retinoid-resistant acinar cell lines.

Conclusions: Detailed knowledge of nuclear retinoid receptor expression may provide rational strategies for retinoid treatment of pancreatic cancer.