Hepatocellular carcinoma

Effects of the combination of As2O3 and AZT on proliferation inhibition and apoptosis induction of hepatoma HepG2 cells following silencing of Egr-1

Context

Previous studies have demonstrated that 3′-azido-3′-deoxythymidine (AZT) and arsenic trioxide (As₂O₃), traditional chemotherapy agents, can synergically inhibit the growth of hepatocellular carcinoma cells. However, the molecular mechanisms underlying As₂O₃ and AZT anti-hepatoma activity are unknown.

Objective

This study aimed to investigate the role of early growth response protein 1 (Egr-1) in the process of As₂O₃ combined with AZT inhibiting proliferation and inducing apoptosis of human hepatocellular carcinoma HepG2 cells, and explore the possible mechanism.

Materials and methods

The expression of Egr-1 was silenced using siRNA, and then HepG2 cells were treated with As₂O₃ (2 μM) and AZT (20 μM). The rates of cell inhibition and apoptosis were determined by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) method and flow cytometry, respectively. The mRNA and protein expression of p53, caspase-3, and Egr-1 were detected by real-time quantitative polymerase chain reaction and Western blotting, respectively.

Results

The inhibitory rate of As₂O₃ (2 μM) combined with AZT (20 μM) on proliferation of HepG2 cells was significantly higher than that of As₂O₃ alone. The combination index (CI) values were 0.2<CI<0.4, showing strong synergic effect. After silencing Egr-1, the proliferation inhibition and proapoptotic ability of As₂O₃ combined with AZT on HepG2 cells were decreased, and the CI value was greater than 1, showing antagonistic effect. In addition, the expression of p53 and caspase-3 mRNA/protein was also significantly decreased.

Conclusion

The present results show that AZT could increase the sensitization of As₂O₃ for inhibiting proliferation and promoting apoptosis of HepG2 cells through regulating the expression of Egr-1, which may control the expression of p53 and caspase-3.

Effect of iron chelators on proliferation and iron uptake in hepatoma cells

BACKGROUND

The siderophore desferrioxamine mesylate (DFO) is used routinely in clinical practice to treat diseases of iron (Fe) overload. Recent studies suggest that DFO and other chelators may have potential in the treatment of cancer. The current study reports the findings obtained when a number of chelators with varying membrane permeability, Fe-binding affinity, and preference for either Fe(3+) or Fe(2+) were assessed for their antineoplastic potential in vitro against hepatocellular carcinoma cells (HCC) because to the authors' knowledge there are few effective treatment methods for this aggressive neoplasm.

METHODS

A number of criteria were investigated, including the effects of the chelators on cell proliferation, selectivity, Fe uptake, toxicity, and cell cycle progression.

RESULTS

The results obtained showed that Fe binding affinity did appear to influence Fe chelator activity but was not an absolute factor, and that certain ferric and ferrous, membrane-permeable and membrane-impermeable Fe chelators demonstrated antiproliferative activity and selectivity against HCC. All effective chelators inhibited Fe uptake from Tf-(59)Fe in both hepatoma cells and normal hepatocytes. However, these chelators all had much lower effects on the survival of normal proliferating and nonproliferating cells. The effects on cell cycle were more varied between chelators, as were levels of toxicity.

CONCLUSIONS

The results of the current study indicate that a number of different Fe chelators have the potential to treat HCC, and that further investigation into their mechanisms of action is warranted.

The National Cancer Data Base Report on treatment patterns for hepatocellular carcinomas: improved survival of surgically resected patients, 1985-1996

BACKGROUND

The Commission on Cancer data from the National Cancer Data Base (NCDB) has previously reported data evaluating time trends in various cancers, including such elements as stage of disease at diagnosis, treatment, and survival for multiple tumor sites. In this report, data collected from 1985, 1986, 1990, 1991, 1995, and 1996 for primary hepatocellular carcinoma (HCC) tumors are presented.

METHODS

The data presented in this review were collected from hospital cancer registries from across the U.S. Eight calls for data have yielded a total 6.9 million cases for the years 1985-1996, including 1158 HCC cases in 1985-1986, 3319 cases in 1990-1991, and 5683 cases in 1994-1995 from hospital cancer registries across the U. S. These data represent approximately 4.3%, 11.2%, and 14.8% of the estimated cases of carcinomas of the liver and biliary tract diagnosed in the U.S. in each of the three respective time periods.

RESULTS

The outcome for patients diagnosed with HCC remains poor, with only 10% of patients with American Joint Committee on Cancer Stage I disease surviving 5 years. Approximately 50% of patients received no therapy for their HCC, even those with early stage disease. Over these three time periods, the use of chemotherapy appears to have decreased. Among patients diagnosed with Stage II and III disease a difference in survival was noted between those treated with surgery only and those treated with chemotherapy only. Women appear to have a limited survival advantage over men.

CONCLUSIONS

In spite of an overall poor prognosis, subsets of patients with HCC appear to benefit from surgical resection/ablation of their tumor. The decreasing use of chemotherapy and the early reports of newer ablative techniques (e.g., cryotherapy) suggest that other treatment modalities are emerging. These NCDB data provide a baseline for HCC treatment from which prospective studies are being developed to assess the newer treatments as well as the underlying causes.

Management options for primary hepatocellular carcinoma. An overview

Hepatocellular carcinoma (HCC) is the seventh most common cancer in men and the ninth most common cancer in women with 500,000 to 1,000,000 new cases per year. Several risk factors (sex hormones, alcohol, thorotrast, aflatoxin B1, hepatitis B or C, haemochromatosis, alpha 1-antitrypsin deficiency, tyrosinemia, porphyria cutanea tarda, acute intermittent porphyria, Wilson's disease) associated with the development of HCC have been identified from epidemiological studies. The diagnosis is usually based on a combination of clinical and laboratory findings together with radiographic and histopathologic characteristics. HCC remains difficult to treat with a median survival of 3 to 6 months after the onset of symptoms. Surgical resection is the mainstay of treatment for HCC. Transcatheter arterial embolization and percutaneous ethanol injection have been used but neither therapy has been evaluated in a prospective randomized study. Combination treatment (e.g. chemotherapy and resection) may be of value but randomized controlled trials with long-term follow-up are still needed. Liver transplantation should be reserved for carefully selected patients.

Hepatitis in the tropics

Viral hepatitis, caused by one of five different viruses, is an important cause of illness in tropical countries and a significant cause of death. Vaccines against hepatitis A and B are now available and, if used widely, have the potential virtually to eliminate both these diseases (and also hepatitis D). Vaccines against hepatitis C and E are being developed.