Increased expression of c-jun gene during spontaneous hepatocarcinogenesis in LEC rats

Bioinformatics analysis identifies miR-221 as a core regulator in hepatocellular carcinoma and its silencing suppresses tumor properties

Hepatocellular carcinoma (HCC) is a worldwide malignancy; however, there is a lack of effective targeted therapies. We and others have found that miR-221 is one of the most consistently overexpressed miRNAs in liver cancer. However, the roles of miR-221 in hepatocellular carcinogenesis are still not fully elucidated. In the present study, we used bioinformatics tools, gain- and loss-of-function methods to determine the roles of miR-221 in HCC. Bioinformatics analysis showed that miR-221 is a core miRNA which targets a large number of HCC-related genes and has formed many feed-forward regulatory loops combining transcription factors (TFs) to regulate HCC-related genes. Inhibition of miR-221 in liver cancer cells decreased cell proliferation, clonogenicity, migration/invasion and also induced G1 arrest and apoptosis. In addition, we demonstrated that miR-221 bound directly to the 3'-untranslated region of BMF, BBC3 and ANGPTL2, and inhibited the expression of BMF, BBC3 and ANGPTL2. In a mouse model, lentivirus‑mediated miR-221 silencing could significantly suppress the growth of hepatoma xenografts in nude mice. In conclusion, we showed that miR-221 is a critical modulator in the HCC signaling pathway, and miR-221 silencing inhibits liver cancer malignant properties in vitro and in vivo, which may benefit the treatment for patients with unresectable HCC.

Cucurbitacin B induces apoptosis and S phase cell cycle arrest in BEL-7402 human hepatocellular carcinoma cells and is effective via oral administration

Cucurbitacin B is an anti-cancer drug candidate and its efficacy has been demonstrated in hepatocellular carcinoma (HCC). To explore its mechanism against HCC, BEL-7402 cells were treated with cucurbitacin B in vitro. Treatment with cucurbitacin B induced S phase arrest and apoptosis. The growth inhibition effect was associated with cyclin D1 and cdc-2 down regulations. Western blotting analysis of cell signaling molecules indicated that cucurbitacin B inhibited c-Raf activation without affecting STAT3 phosphorylation. Moreover, in vivo study demonstrated that cucurbitacin B is effective against BEL-7402 xenograft when administrated orally.

Protein kinase p-JNK is correlated with the activation of AP-1 and its associated Jun family proteins in hepatocellular carcinoma

To study the role of c-Jun N-terminal kinase (JNK) and its relation to transcription factor AP-1 and Jun family proteins in hepatocellular carcinoma (HCC) with or without hepatitis B virus (HBV) infection. Immunohistochemical and in situ hybridization techniques were performed for studying phosphorylated JNK (p-JNK), c-Jun, JunB, JunD and AP-1 in 40 cases of human HCC and corresponding nontumoral tissues. Positive staining of nucleus for p-JNK, c-Jun, JunD and AP-1 was presented in 28 (70%), 29 (72.5%), 32 (80%) and 25 (62.5%) in cancer cells respectively, while 0%, 28%, 17.5% and 10% in adjacent non-tumor tissues. The expression levels of p-JNK, c-Jun, JunD and AP-1 were significantly and positively correlated with each other and with HBsAg positive rate (P<0.05). JunB was negative staining in both cancer cells and non-tumor tissues of all cases. JNK phosphorylation may correlate with AP-1 activation and the expression of c-Jun and JunD in HCC. JNK/c-Jun/JunD/AP-1 signaling pathway may play an important role in the pathogenesis of HBV-associated HCC. JunB may not be involved in the process.

Accumulation of diacylglycerol in the liver membrane of the Long-Evans Cinnamon (LEC) rat with hepatitis: FT-IR spectroscopic and HPLC detection

Long-Evans Cinnamon (LEC) rats develop severe hepatitis and subsequent hepatoma with excess accumulation of copper in the liver with increasing age. Lipids extracted from the LEC rat liver membrane were studied using FT-IR spectroscopy and an HPLC technique at the stages of pre-hepatitis and hepatitis, i.e. at 10 and 16 weeks of age, respectively. The 10-week-old rats exhibited an IR spectrum characteristic of a phosphatidylcholine and phosphatidylethanolamine mixture with a ratio of 2:1. The 16-week-old rats developed new absorption bands at 1161 and 1070 cm(-1), which were assigned to the spectra of triglyceride, neutral lipid, and diacylglycerol, an endogenous activator of protein kinase C, respectively. The diacylglycerol was estimated to amount to ca. 10% (w/w) of phospholipid extract by comparing the spectrum with those of model compounds. This was confirmed using an HPLC assay. Previously, we found that a serum response factor is activated by copper in the LEC rat liver, and suggested that it must mediate proto-oncogene c-fos induction. The results obtained here suggest that accumulation of diacylglycerol plays an important role in development of hepatoma in LEC rats by mediating proto-oncogene c-fos induction.

Activation of serum response factor in the liver of Long-Evans Cinnamon (LEC) rat

We have studied the DNA binding activities of transcription factors in the liver of Long-Evans Cinnamon (LEC) rats, an animal model of Wilson's disease. Owing to a genetic defect, this strain of rats accumulates excessive copper in the liver and develops severe hepatitis and hepatocellular carcinoma. We found that the DNA binding activity of the serum response factor (SRF) was higher in the liver of LEC rats (approximately 2-fold) than in that of Wistar rats. There was a close correlation between the intensity of the activity and the concentrations of copper in the nuclear protein. The DNA binding activity of Sp1, on the other hand, showed similar levels in both LEC and Wistar rats. SRF may play an important role in the development of hepatocellular carcinoma in LEC rats by mediating the proto-oncogene c-fos induction. We suggest that the copper in nuclear protein may be involved in the activation of SRF.