In vivo anti-lymphoma activity of an agonistic human recombinant anti-TRAIL-R2 minibody

The Strategy of Conditionally Replicating Adenovirus-Mediated PreS2 Mini-Antibody Expression Has Dual Effects of Inhibiting HBV Infection and Preventing Hepatocellular Carcinoma

Aim

To investigate the inhibitory effect of hepatitis B virus (HBV) preS2 mini-antibody (mPreS2) against HBV infection, HBV-associated liver injury and HBV-associated hepatic carcinogenesis.

Methods

A recombinant adenovirus vector with the human survivin promoter and mPreS2 gene, Ad5SVP-mPreS2, was constructed. Fluorescence microscopy examination and TCID 50 analysis were utilized to determine the specific proliferation of recombinant adenovirus in liver cancer cells. Western blot analysis was used to determine the mPreS2 expression levels. Enzyme-linked immunosorbent assay (ELISA) was used to examine HBsAg levels to evaluate the inhibitory effect of mPreS2 against HBV infection. The protective effects on hepatic function and preventive effects against hepatic carcinogenesis of Ad5SVP-mPreS2 were studied in diethylnitrosamine (DEN)-treated HBV transgenic Imprinting Control Region mice.

Results

The recombinant adenovirus regulated by the human survivin promoter proliferated exclusively in liver cancer cells rather than normal liver cells. The expression levels of mPreS2 were increased in liver cancer cells compared with normal liver cells, and mPreS2 could be used to recognize liver cells from HBV transgenic mice. ELISA showed that HBsAg levels were decreased in the group treated with Ad5SVP-mPreS2. Ad5SVP-mPreS2 had a protective effect on hepatic function in a DEN-induced liver injury model because of lower serum levels of alanine transaminase and aspartate transaminase. Additionally, HBV transgenic mice treated with Ad5SVP-mPreS2 had fewer and smaller cancerous nodes after induction with DEN than untreated mice.

Conclusion

Conditionally replicating adenovirus-mediated mPreS2 expression inhibited HBV infection and had an inhibitory effect on liver injury and hepatocellular carcinogenesis in HBV transgenic mice.

Molecular Mode of Action of TRAIL Receptor Agonists-Common Principles and Their Translational Exploitation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its death receptors TRAILR1/death receptor 4 (DR4) and TRAILR2/DR5 trigger cell death in many cancer cells but rarely exert cytotoxic activity on non-transformed cells. Against this background, a variety of recombinant TRAIL variants and anti-TRAIL death receptor antibodies have been developed and tested in preclinical and clinical studies. Despite promising results from mice tumor models, TRAIL death receptor targeting has failed so far in clinical studies to show satisfying anti-tumor efficacy. These disappointing results can largely be explained by two issues: First, tumor cells can acquire TRAIL resistance by several mechanisms defining a need for combination therapies with appropriate sensitizing drugs. Second, there is now growing preclinical evidence that soluble TRAIL variants but also bivalent anti-TRAIL death receptor antibodies typically require oligomerization or plasma membrane anchoring to achieve maximum activity. This review discusses the need for oligomerization and plasma membrane attachment for the activity of TRAIL death receptor agonists in view of what is known about the molecular mechanisms of how TRAIL death receptors trigger intracellular cell death signaling. In particular, it will be highlighted which consequences this has for the development of next generation TRAIL death receptor agonists and their potential clinical application.