[Relationship between TIMP-3 expression and promoter methylation of TIMP-3 gene in hepatocellular carcinoma].
OBJECTIVE
To investigate further the possible mechanism of carcinogenesis and portal invasion of hepatocellular carcinoma (HCC).


METHODS
Samples of the primary tumors, cancer cells emboli in the portal veins and normal liver tissues adjacent to the tumor were collected from 20 cases of primary HCC. Expression of TIMP-3 (tissue inhibitor of metalloproteinases-3) protein was detected using Western blot. Expression of TIMP-3 mRNA was detected by RT-PCR. Methylation of TIMP-3 gene promoter was detected using methylation-specific PCR (MSP).


RESULTS
Expression of TIMP-3 protein and mRNA were obtained in all of the normal liver tissues adjacent to tumor. However, loss of TIMP-3 protein expression was found in 5 and 36 cases respectively in the primary tumors and tumor cell emboli in portal veins. Expression of TIMP-3 protein and mRNA in primary tumors and tumor emboli were significantly lower than that in the normal liver tissues. Promoter methylation of TIMP-3 gene could be detected in primary tumors (7 cases) and cancerous emboli (9 cases) in HCC, while no methylation found in normal liver tissues. In all the HCC cases with promoter gene methylation including primary tumors and cancerous emboli in portal veins, 13 cases showed complete loss and 6 cases showed low expression of TIMP-3 protein and mRNA. Promoter methylation of TIMP-3 was noticed not related with the histological grading of HCC.


CONCLUSIONS
There is a close relationship between loss or low expressions of TIMP-3 and carcinogenesis and portal invasion of HCC. The loss and low expression of TIMP-3 gene and protein were caused by methylation of the gene promoter.
Lü
Guo-li
GL
Department of Pathology, Zhongshan Medical College, Sun Yat-sen University, Guangzhou 510080, China.
Wen
Jian-ming
JM
Xu
Jian-min
JM
Zhang
Meng
M
Xu
Ruo-bing
RB
Tian
Bao-ling
BL
D000328:Adult; D000368:Aged; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000737:chemistry / Q000235:genetics*; D018899:CpG Islands; D019175:DNA Methylation; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000032:analysis / Q000235:genetics*
D019717:Tissue Inhibitor of Metalloproteinase-3