| Carcinogenesis of primary liver tumor has ever been attributed to dedifferentiation of mature cells; however, recent studies hold that it might be caused by disdifferentiation of hepatic stem cell (HSC). HSC is an undifferentiated cell that can renew itself unlimitedly and capable of multi-potential differentiation. HSC not only can be intrahepatic origin, of which hepatic oval cell (HOC) is the representative one, but also can be derived from bone marrow (BM) or peripheral circulatory system. HSC takes a great role in the repair of damaged liver; however, it also gives rise to tumor and preserves specific immunological markers during certain periods when abnormal differentiation appears. Activation, proliferation, and differentiation of stem cell is determined by histological microenvironment, so there are inevitably some factors regulating primary liver carcinoma arising from HSC. In this research, we take an initial study about the expression of HSC in primary liver carcinoma and about factors of induction differentiation of liver cancer. This would be helpful to provide theoretical support for pathological diagnosis, molecular targeting therapy or differentiation therapy, and prognosis assessment in primary liver carcinoma. In the first part of this experiment, 53 cases of primary hepatic carcinoma were observed through hematoxylin-eosin (HE) dyeing and immunohistochemistry, with 5 cases of sclerosing liver and 4 cases of normal liver tissues as experimental control. Meanwhile, 6 cases of hepatocellular carcinoma (HCC), 1 cases of intrahepatic cholangiocarcinoma (ICC), 4 cases of sclerosing liver and 4 cases of normal liver were observed under transmitting electron microscopy. Results: (1) HOCs were observed and transformed into carcinoma in liver. (2) cytokeratin (CK)7,CK19,c-kit,Thy-1,alpha fetoprotein(AFP) are expressed at different intensity in primary liver carcinoma. (3) Small cell type, intermediate type and pseudoductular type of HCC were observed with less differentiation and stronger immunological expression. In the second part, a hepatic carcinoma cell line--HepG2 was cultured in vitro with supernatants from fetal liver cells (FLCS) and bone marrow mesenchymal stem cells (BMMSC) and leukemia serum at different concentration. The techniques of inverted microscope, electron microscopy, immunohistochemistry, flow cytometry and reverse transcript polymerase chain reaction (RT-PCR) were applied to investigate the alternations of HepG2 cells under those conditioned cultures. Results: (1) HepG2 cells expressed CK7, CK19, AFP, vimentin, c-kit, Thy-1, CD34 and the corresponding mRNA as well. (2) In the group cultured with FLCS, HepG2 cells were inhibited and showed differentiation. Growth fraction declined when the dose of supernatant increased. (3) In the group from BMMSC and leukemia serum, HepG2 cells grew in quicker pace and showed differentiation. Also, growth fraction increased with supernatant. Conclusions 1. There were HSCs showing typically oval-cell shape in cancerous tissues and paracancerous tissues. HSCs might result in carcinoma by disdifferentiation. 2. HSCs might be multi-source, derived from intrahepatic origin and BM or circulating pluripotent stem cells. 3. Primary liver carcinoma displaying different histological structure might be caused by the heterogeneity and different differentiation of HSCs. 4. HepG2 cells shared stem cell phenotype provided further evidence for theory of the origin of stem cell in hepatoma. 5. The growth of HepG2 cells that could be regulated and induced by FLCS, BMMSC and leukemia serum might imply the hepatoma cells hold the possibility of induction differentiation.
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