[Effect of siRNA-mediated inhibition of nuclear transcription factor-kappa B on apoptosis of hepatocarcinoma cells].

OBJECTIVE: To investigate the effect of siRNA-mediated inhibition of NF-κB on apoptosis of hepatocarcinoma cells. METHODS: Specific small interfering RNA Targeting NF-κB gene was synthesized and transfected into HepG2 cells by liposomes. Nested RT-PCR and quantitative RT-PCR were used to detect the mRNA expression of NF-κB. Immunohistochemistry, enzyme-linked immunosorbent assay and Western blot were performed to examine the protein expression of NF-κB. Annexin V-FITC was used to test cell apoptosis. RESULTS: The expression of NF-κB in HepG2 cells (1.13+/-0.03) was significantly higher (t=27.02, P<0.05) than that in normal hepatocytes (0.29+/-0.07). The down-regulation of NF-κB expression was depended on the dosage of siRNA and the time after transfection. 72 h after siRNA transfection, NF-κB expression reduced by 93% and 62% at the mRNA and protein levels, respectively. The apoptosis of HepG2 cells increased by 85% with NF-κB inhibition. CONCLUSIONS: NF-κB is abnormally active in HepG2 cells and NF-κB inhibition mediated by siRNA promotes HepG2 cells apoptosis. It suggested that NF-κB could be a potential target for HCC prevention gene therapy.

Characteristics of hepatic nuclear-transcription factor-kappa B expression and quantitative analysis in rat hepatocarcinogenesis.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. We analyzed the expression of nuclear-transcription factor-kappa B (NF-kappaB) during hepatocarcinogenesis in order to evaluate its dynamic expression and its clinical value in the development and diagnosis of HCC. METHODS: Hepatoma models were induced by oral administration of 2-acetamidoflurene (2-FAA) to male Sprague-Dawley rats. Morphological changes were observed after hematoxylin and eosin staining. The cellular distribution of NF-kappaB expression during different stages of cancer development was investigated by immunohistochemistry, and the level of NF-kappaB expression in liver tissues was quantitatively analyzed by ELISA. The gene fragments of hepatic NF-kappaB were amplified by nested-polymerase chain reaction assay. RESULTS: Hepatocytes showed vacuole-like degeneration during the early stages, then had a hyperplastic nodal appearance during the middle stages, and finally progressed to tubercles of cancerous nests with high differentiation. The NF-kappaB-positive material was buff-colored, fine particles localized in the nucleus, and the incidence of NF-kappaB-positive cells was 81.8% in degeneration, 83.3% in precancerous lesions, and 100% in cancerous tissues. All of these values were higher than those in controls (P<0.01). Hepatic NF-kappaB expression and hepatic NF-kappaB-mRNA were also higher during the course of HCC development (P<0.01). CONCLUSION: The NF-kappaB signal transduction pathway is activated during the early stages of HCC development, and its abnormal expression may be associated with the occurrence of HCC.

[Dynamic expression and quantitative analysis of hepatic nuclear factor-kappa B and its gene during the development of hepatocellular carcinoma].

OBJECTIVE: To investigate the kinetic expression and alteration of nuclear transcription factor-kappa B (NF-kappaB) and its gene in hepatocellular carcinoma (HCC) development. METHODS: A hepatoma model was established with N-(2-fluorenyl) acetamide (2-FAA) using male SD rats. Morphological changes and dynamic alterations of NF-kappaB and NF-kappaB mRNA of the rat livers at different stages of HCC development were observed by pathological examinations. The liver specimens from HCC patients were collected by self-control method. The expression of NF-kappaB was quantitatively analyzed by ELISA. RESULTS: Hepatocytes showed vacuole-like denaturation, atypical hyperplasia, and transformation into highly differentiated cancerous hepatocytes with increasing tendencies of liver NF-kappaB and NF-kappaB mRNA expressions. The NF-kappaB positive material was granule-like and stained brown, with dot-nest-like staining localized in the nuclei and cytoplasm of HCC cells, but only in the cytoplasm of the cells of park cancer tissues. Its expression in HCC cells was stronger than that in their surrounding tissues (chi2 = 13.1, P less than 0.01). No positive relationship was found between NF-kappaB expression and histological grades, the number of tumors, or size of the tumors. CONCLUSION: The expression of NF-kappaB and its gene are associated with the development of HCC. To inhibit the expression may be useful to HCC therapy.

Reversal of multidrug resistance of hepatocellular carcinoma cells by metformin through inhibiting NF-κB gene transcription.

AIM: To interfere with the activation of nuclear factor-κB (NF-κB) with metformin and explore its effect in reversing multidrug resistance (MDR) of hepatocellular carcinoma (HCC) cells. METHODS: Expression of P-glycoprotein (P-gp) and NF-κB in human HepG2 or HepG2/adriamycin (ADM) cells treated with pCMV-NF-κB-small interference RNA (siRNA) with or without metformin, was analyzed by Western blot or fluorescence quantitative PCR. Cell viability was tested by CCK-8 assay. Cell cycle and apoptosis were measured by flow cytometry and Annexin-V-PE/7-AnnexinV apoptosis detection double staining assay, respectively. RESULTS: P-gp overexpression in HepG2 and HepG2/ADM cells was closely related to mdr1 mRNA (3.310 ± 0.154) and NF-κB mRNA (2.580 ± 0.040) expression. NF-κB gene transcription was inhibited by specific siRNA with significant down-regulation of P-gp and enhanced HCC cell chemosensitivity to doxorubicin. After pretreatment with metformin, HepG2/ADM cells were sensitized to doxorubicin and P-gp was decreased through the NF-κB signaling pathway. The synergistic effect of metformin and NF-κB siRNA were found in HepG2/ADM cells with regard to proliferation inhibition, cell cycle arrest and inducing cell apoptosis. CONCLUSION: Metformin via silencing NF-κB signaling could effectively reverse MDR of HCC cells by down-regulating MDR1/P-gp expression.