Background & objective: Previous study of our laboratory showed that 67kD laminin receptor (67LR) from SMMC-7721 hepatocellular carcinoma (HCC) cells had higher binding affinity with laminin than that from L-02 normal hepatic cells; however, the expression level of 67LR in HCC cells and normal hepatic cells was still unknown. The aim of this study was to investigate the relationship between laminin binding activity and the expression of mRNA and protein of 67kD laminin receptor in SMMC-7721,HepG2 HCC cells, and L-02 hepatic cells.
Methods: (1) The binding of laminin with three kinds of cells was quantified by (131)I-labeled laminin. (2)The expression of 67kD laminin receptor was determined by the reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry.
Results: (1) Under the same condition, the amount of radiolabelled laminin bound to SMMC-7721, HepG2 HCC cells was 17.54+/-0.49 ng per 10(5) cells and 11.18+/-0.53 ng per 10(5) cells, respectively, which were significantly higher than that to L-02 hepatic cells (8.36+/-0.48 ng per 10(5) cells). The binding of laminin with HCC cells is specific and saturable, and the cells bound exogenous laminin with high affinity. (2) 67 LR showed notably increased expression on the surface of L-02 hepatic cells (55.3%), compared with SMMC-7721 HCC cells (34.7%) by flow cytometry. HepG2 did not express membrance 67 LR. (3) The expression of 67LR mRNA in SMMC-7721 and HepG2 HCC cells was higher than that in L-02 cells.
Conclusion: The conflict of laminin binding activity and the expression of 67 LR in the three cell lines suggested SMMC-7721 HCC cells may express 67 LR with higher laminin affinity than L-02 hepatic cells, and other laminin receptors were involved in laminin binding.