No abstract

Chronic hepatitis C virus (HCV) infection is associated with the production of serum cytokines, including transforming growth factor (TGF)-␤2. Despite the occurrence of hepatic angiogenesis in liver conditions, the role of HCV proteins in this context is currently unknown. We demonstrated that the development of hepatic neoangiogenesis in patients infected with HCV is associated with the expression of TGF-␤2 and vascular endothelial growth factor (VEGF) and with activation of endothelial cells, as evidenced by CD34 expression. The analysis of liver biopsies of HCV-positive and HCV-negative patients using immunostaining showed significant elevation of TGF-␤2, VEGF, and CD34 expression in patients who were HCV-positive. Using an HCV established culture system, we confirmed further the production of both TGF-␤2 and VEGF proteins, in the hepatoma cell lines HepG2 and Huh7 by transfection with full-length HCV RNA (JFH1) or by the regulated expression of core. In addition, regulated expression of core protein in HepG2 or Huh7 cells was found to induce expression and activation of the transcription factor E2F1 and apoptosis signal-regulating kinase 1 (ASK1), activation of c-jun-N-terminal kinase (JNK) and p38, and extracellular-regulated kinase (ERK), and transcription factors activator protein 1 (AP-1), activating transcription factor 2 (ATF-2), cyclic adenosine monophosphate response element binding (CREB), E2F1, hypoxia inducing factor 1 alpha (HIF-1␣), and specificity protein 1. Furthermore, data obtained from inhibitor experiments revealed the importance of E2F1 and ASK1 in the modulation of core-induced activation of JNK and p38 pathways and suggested an essential role for JNK, p38, and ERK pathways in the regulation of core-induced production of TGF-␤2 and VEGF proteins. Thus, our data provide insight into the molecular mechanisms whereby core protein mediates the development of hepatic angiogenesis in patients with chronic HCV infection.

Although chemotherapeutic drugs could theoretically target all metastatic sites, current treatments do not provide complementary therapeutics. Therefore, the development of an alternative approach replacing the traditional therapy is urgently needed. To assess the killing efficiency of the functionally identified apoptosis-related protein (APR)-1 in melanoma cells, we established a system for the regulated expression of APR-1. The induction of APR-1 expression caused apoptosis of melanoma cells via the interaction with the juxtamembrane region of p75 neurotrophin receptor (p75NTR), and possible also via the competition with tumour necrosis factor receptor-associated factor-6 (TRAF6) and the catalytic receptor of neurotrophin (Trk) for the same p75NTR interacting site. The accumulation of APR-1 in melanoma cells may block the physical association of p75NRT with TRAF6 and/or Trk, leading to the disruption of both NF-κB and extracellular signal-regulated kinase (ERK) pathways. Also, accumulation of APR-1 protein enhanced the activity of both c-Jun-N-terminal kinase (JNK) and p38 pathways. However, the analysis of APR-1-modulated pathways demonstrated the involvement of apoptosis-regulating kinase 1-JNK/p38 pathway in the induction of Bax expression leading to both mitochondrial dysregulation [as demonstrated by the loss of mitochondrial membrane potential, the release of both cytochrome c and apoptosis-inducing factor into cytoplasm, and cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP)] and endoplasmic reticulum stress as demonstrated by the increase of intracellular Ca2+ release. Thus, besides the analysis of its pro-apoptotic function, our data provide insight into the molecular mechanism of APR-1-induced apoptosis of melanoma cells.