Analysis of matrix metalloproteinase mRNAs expressed in hepatocellular carcinoma cell lines

To analyze matrix metalloproteinase (MMP) mRNAs that are expressed in hepatocellular carcinoma cell lines, the kinds of MMP mRNAs were surveyed in HepG2 and Hep3B cells and normal liver by a reverse transcription-polymerase chain reaction using two degenerate primer pairs, derived from conserved domains of known MMPs. The level for each MMP mRNA was examined by Northern blot analysis in HepG2 and Hep3B cells, as well as in normal tissues. It was also examined by a reverse transcription-polymerase chain reaction analysis in 8 different hepatocellular carcinoma cell lines. MMP-2, MMP-14, and MMP-15 mRNAs were expressed at elevated levels in most of the cell lines studied, reflecting that these MMPs would play an important role in the invasion and metastasis of hepatocellular carcinoma. MMP-1, MMP-3, MMP-8, MMP-10, MMP-11, and MMP-13 mRNAs were also expressed in some or most of the cell lines. Interestingly, MMP-9 mRNA, as well as its polypeptide, was undetected in all of the cell lines studied. This implies that MMP-9, which was suggested as a tumor marker for hepatocellular carcinoma, would be expressed in stromal cells, rather than tumor cells. These results provide information for the basal levels of MMP mRNAs in various hepatocellular carcinoma cell lines. It will also facilitate study on the transcriptional regulation of each MMP mRNA by oncogenes.