Features Of Insulin-like Growth Factor-II Expression And Dynamic Alteration Of Apoptotic-related Protein (bcl-2) During Malignant Transformation Of Hepatocytes

Objective Hepatocellular carcinoma (HCC) is a common hepatic malignancy worldwide. Its nature of rapid growth results in a grave prognosis. The progression of HCC is closely associated with over- expression of hepatic growth factors. However, the molecular mechanisms and alteration features of growth factors are still largely unknown. In the present study, the gene expression profiling, dynamic expression of insulin-like growth factor-II (IGF-II), IGF-binding protein-3 (IGFBP-3) and B-cell lymphomas-2 (bcl-2) were investigated during development of HCC for exploring its molecular mechanism and the clinical significance of early diagnosis.Methods Rat hepatoma models were induced with 2-fluorenylacetamide (2-FAA) on male Sprague-Dawley (SD) rats. Gene expression profiling was analyzed by rat DNA array, morphological changes were observed by pathological examinations (HE staining), dynamic alterations of liver IGF-II and bcl-2 at different stages of HCC were analyzed by immunohisto- chemistry. Simultaneously, liver and serum IGF-II,liver IGFBP-3,and bcl-2 were also quantitatively analyzed by enzyme linked immunosorbent assay (ELISA).RESULTS The up-regulated expressions of 2898 genes at early stages and 3208 genes at end stages were found by DNA array analysis among total 28000 genes during the course of HCC formation and development. The hepatocytes showed vacuole-like denaturation at the early stages, then hyperplastic nodal appearance at middle stage, and finally progression to tubercles of cancerous nest with highly differentiated hepatocyte cancers during development of rat hepatoma. Rat hepatocytes from granule-like degeneration to a typical hyperplasia to HCC and the progressing increasing of the levels of hepatic IGF-II after induced by 2-FAA. The levels of IGF-II in hepatoma and sera were significantly higher than any of other groups. The positive correlation of IGF-II was found between liver and sera (P<0.01). The IGFBP-3 levels in hepatoma were significantly lower than that in other groups (P<0.01),and the progressing increasing of the levels of hepatic bcl-2 expression during the course. The levels of bcl-2 in hepatoma tissues were significantly higher than those in normal and degeneration ones. The immunohistochemistry evidences indicated the positive expression and hepatocyte distribution of bcl-2 in rat hepatoma.CONCLUSIONS Multigenes including hepatic IGF-II would participate in multistages during the course of hepatocyte canceration with the increases of IGF-II and bcl-2 expression and reducing IGFBP-3, they maybe accelerate the occurrence and development of HCC. The significantly expressions of hepatic IGF-II and bcl-2 at the early stage of HCC formation could be useful sensitive molecular markers for monitoring the malignant transformation of hepatocyte.