Chronic hepatitis B in hepatocarcinogenesis

Viruses associated with human cancer

It is estimated that viral infections contribute to 15-20% of all human cancers. As obligatory intracellular parasites, viruses encode proteins that reprogram host cellular signaling pathways that control proliferation, differentiation, cell death, genomic integrity, and recognition by the immune system. These cellular processes are governed by complex and redundant regulatory networks and are surveyed by sentinel mechanisms that ensure that aberrant cells are removed from the proliferative pool. Given that the genome size of a virus is highly restricted to ensure packaging within an infectious structure, viruses must target cellular regulatory nodes with limited redundancy and need to inactivate surveillance mechanisms that would normally recognize and extinguish such abnormal cells. In many cases, key proteins in these same regulatory networks are subject to mutation in non-virally associated diseases and cancers. Oncogenic viruses have thus served as important experimental models to identify and molecularly investigate such cellular networks. These include the discovery of oncogenes and tumor suppressors, identification of regulatory networks that are critical for maintenance of genomic integrity, and processes that govern immune surveillance.

Vaccines: an innovative approach to treating cancer

Recent scientific advances have expanded our understanding of the immune system and its response to malignant cells. Clinical trials are under way that attempt to translate this knowledge into effective cancer therapies. Vaccine therapy, an innovative approach to cancer treatment, attempts to activate the immune system to recognize cancer cells and eliminate them from the body. Preventive vaccines that already have been approved will have an impact on the incidence of certain cancers, and research is ongoing into treatment vaccines for various cancers.

Biochemical Rather than Virologic Response to Interferon Therapy may be More Closely Associated with Decrease of Hepatocellular Carcinoma Incidence in Patients with Chronic Hepatitis B

BACKGROUND/AIMS

The authors examined whether the response to interferon (IFN) therapy can affect the development of hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) patients.

METHODS

Out of 353 biopsy-proven CHB patients, 229 (65%) were treated with IFN-alpha for 6 to 12 months. They were followed for a median period of 75 months (range, 6-120). In patients treated with IFN, biochemical and virologic responses were evaluated at the end of treatment (EOT). The cumulative incidence rates of HCC were calculated and analyzed in relation to baseline characteristics as well as biochemical and virologic responses to IFN therapy.

RESULTS

The overall cumulative incidence of HCC was 0%, 0.8%, 3.7% and 5.5% at 3, 5, 7 and 8 years, respectively. Age, serum AFP levels and the stage of fibrosis were significantly associated with the occurrence of HCC. As a whole, IFN therapy did not affect the occurrence of HCC. Among the patients treated with IFN, biochemical responders had low HCC incidence rates compared with non-responders (p=0.018). However, the HCC incidence rates of virologic responders were not different from non-responders (p=0.203).

CONCLUSIONS

Biochemical rather than virologic response to IFN therapy may be more closely associated with decrease of HCC incidence in CHB patients.

New molecular targets for hepatocellular carcinoma: the ErbB1 signaling system

Hepatocellular carcinoma (HCC) is a major cause of cancer-related deaths. This malignancy is often diagnosed at an advanced state, when most potentially curative therapies are of limited efficacy. In addition, HCC is a type of tumor highly resistant to available chemotherapeutic agents, which leaves HCC patients with no effective therapeutic options and a poor prognosis. From a molecular perspective, HCC is a heterogeneous type of tumor. However, in most cases, HCC emerges on a background of persistent liver injury, inflammation and hepatocellular proliferation, which is characteristic of chronic hepatitis and cirrhosis. Recent studies have revealed that dysregulation of a limited number of growth and survival-related pathways can play a key role in HCC development. The epidermal growth factor receptor (ErbB1) can be bound and activated by a broad family of ligands, and can also engage in extensive cross talk with other signaling pathways. This system is considered as an important defense mechanism for the liver during acute tissue injury; however, accumulating evidences suggest that its chronic stimulation can participate in the neoplastic conversion of the liver. Agents that target the ErbB1 receptor have shown antineoplastic activity in other types of tumors, but their efficacy either alone or in combination with other compounds has just started to be tested in experimental and human HCC. Here, we review the evidences that support the involvement of the ErbB1 in HCC development and that provide a rationale for ErbB1 targeting in HCC prevention and treatment.