OBJECTIVETo explore the inhibitory effects of endoplasmic reticulum-retained intrabody on the secretion of type IV collagenase and the invasion of human pulmonary giant cell carcinoma PG cells in vitro.

METHODSTwo expression plasmids were constructed, pcDNA3.1-CP.scFv and pcDNA3.1-ER.scFv encoding cytoplasm-retained and endoplasmic reticulum-retained single chain antibodies against the type IV collagenase, respectively. The intracellular antibody genes were transfected into the human pulmonary giant cell carcinoma PG cells. Western blot was performed to detect the expression of pcDNA3.1-CP.scFv and pcDNA3.1-ER.scFv. Gelatin zymography was performed to detect seretion of type IV collagenase in PG cells and Matrigel assay was employed for determination of the cell invasiveness.

RESULTSBoth of cytoplasm-retained and endoplasmic reticulum-retained introbodies, CP.scFv and ER.scFv, were expressed in PG cells. ER.scFv, significantly inhibited the secretion of type IV collegenase. As shown, matrix metalloproteinase 9 and matrix metalloproteinase 2 were inhibited by 85.7% and by 51.2%, respectively. However, CP.scFv did not show such inhibitory effect. The ER.scFv encoding gene-transfected PG cells were much less invasive than parental or vector control cells, the inhibition rate was 76.3% (P < 0.05), whereas CP.scFv encoding gene-transfected PG cells showed no reduction in invasiveness.

CONCLUSIONThose findings demonstrate that endoplasmic reticulum (ER)-retained intracellular antibody technology may selectively abrogate the activity of type IV collagenase in the protein trafficking and secretory pathway and effectively inhibit tumor cell invasion in vitro. Anti-type IV collagenase intrabody may be further used in cancer gene therapy.