New prospects for drug development: the hedgehog pathway revealed. Focus on hematologic malignancies

Procyanidin B2 inhibits the activation of hepatic stellate cells and angiogenesis via the Hedgehog pathway during liver fibrosis

Background

Liver fibrosis is a wound‐healing process of liver featured by the over‐deposition of extracellular matrix (ECM) and angiogenesis. However, the effective treatment is lacking. Procyanidin B2 (PB2) is a flavonoid extract abundant in grape seeds with anti‐oxidant, anti‐inflammatory and anti‐cancer properties. The present study aimed to determine effects of PB2 on liver fibrosis.

Method

The CCl4‐induced mouse liver fibrosis model and a human hepatic stellate cell (HSC) line (LX2 cells) were used to study the activation, ECM production and angiogenesis of HSCs through Western blotting analysis, immunohistochemistry, immunofluorescence staining, flow cytometry and tubulogenesis assay. A Hedgehog (Hh) pathway inhibitor (cyclopamine) and Smoothened agonist (SAG) were used to investigate the role of PB2 on Hh pathway.

Results

The results showed that PB2 could inhibit the proliferation and induce apoptosis of HSCs. PB2 could also down‐regulate the expressions of VEGF‐A, HIF‐1α, α‐SMA, Col‐1 and TGF‐β1 of HSCs in vivo and in vitro. The application of SAG and cyclopamine proved that PB2 targets on Hh pathway.

Conclusions

PB2 inhibited the Hh pathway to suppress the activation, ECM production and angiogenesis of HSCs, therefore reverses the progression of liver fibrosis in vivo and in vitro.

Anti-proliferation of breast cancer cells with itraconazole: Hedgehog pathway inhibition induces apoptosis and autophagic cell death

Itraconazole is a common antifungal which may have promise for treating various human cancers. We report that itraconazole was cytotoxic to MCF-7 and SKBR-3 breast cancer cell lines via apoptosis by altering mitochondria membrane potential, reducing BCL-2 expression and elevating caspase-3 activity. Itraconazole also induced autophagic cell death via LC3-II expression upregulation, P62/SQSTM1 degradation, autophagosome formation and increases in autophagic puncta. Itraconazole treatment inhibited hedgehog pathway key molecular expression, such as SHH and Gli1, resulting in promotion of apoptosis and autophagy. The anti-proliferation effect of itraconazole-induced apoptosis and autophagy via hedgehog pathway inhibition was confirmed with Gli1 inhibitor GANT61 and SHH siRNA, GANT61 and SHH siRNA synergistically enhanced cytotoxicity induced by itraconazole. A human xenograft nude mouse model corroborated the anti-breast cancer activity as evidenced by reduced tumor size, and increased tumor tissue apoptosis and autophagy. Thus, itraconazole has a potent anti-breast cancer activity that may be improved when combined with hedgehog pathway inhibitors.

Hypoxia-mediated autophagic flux inhibits silver nanoparticle-triggered apoptosis in human lung cancer cells

Solid tumors are frequently associated with resistance to chemotherapy because the fraction of hypoxic tumor cells is substantial. To understand the underlying mechanism of hypoxia on silver nanoparticle (AgNPs)-induced apoptosis, the expression of hypoxia-inducible factor (HIF)-1α, a hallmark of hypoxia, was measured in the presence and absence of AgNPs. The results showed that HIF-1α expression was upregulated after AgNPs treatment under both hypoxic and normoxic conditions. Cell viability assays showed that AgNPs promoted cell death in cancer cells but not in non-cancer cells, as cancer cells are slightly more acidic than normal cells. However, reactive oxygen species generation induced by AgNPs in lung cancer cells caused high susceptibility to oxidative stress, whereas pre-exposure to hypoxia blocked AgNPs-induced oxidative stress. Notably, HIF-1α inhibited AgNPs-induced mitochondria-mediated apoptosis by regulating autophagic flux through the regulation of ATG5, LC3-II, and p62. Further, cell viability after treatment of cancer cells with AgNPs under hypoxic conditions was lower in HIF-1α siRNA-transfected cells than in control siRNA-transfected cells, indicating that HIF-1α knockdown enhances hypoxia induced decrease in cell viability. Our results suggest that hypoxia-mediated autophagy may be a mechanism for the resistance of AgNPs-induced apoptosis and that strategies targeting HIF-1α may be used for cancer therapy.

Synthesis and evaluation of novel N-3-benzimidazolephenylbisamide derivatives for antiproliferative and Hedgehog pathway inhibitory activity

7m, as a novel Hedgehog inhibitor, interacted closely with the smoothened receptor at the co-crystallized ligand (taledegib) site.

Hedgehog signaling pathway as key player in liver fibrosis: new insights and perspectives

INTRODUCTION

Activation of hepatic stellate cells (HSCs) is a pivotal cellular event in liver fibrosis. Therefore, improving our understanding of the molecular pathways that are involved in these processes is essential to generate new therapies for liver fibrosis. Greater knowledge of the role of the hedgehog signaling pathway in liver fibrosis could improve understanding of the liver fibrosis pathogenesis.

AREAS COVERED

The aim of this review is to describe the present knowledge about the hedgehog signaling pathway, which significantly participates in liver fibrosis and HSC activation, and look ahead on new perspectives of hedgehog signaling pathway research. Moreover, we will discuss the different interactions with hedgehog signaling pathway-regulated liver fibrosis.

EXPERT OPINION

The hedgehog pathway modulates several important aspects of function, including cell proliferation, activation and differentiation. Targeting the hedgehog pathway can be a promising direction in liver fibrosis treatment. We discuss new perspectives of hedgehog signaling pathway activation in liver fibrosis and HSC fate, including DNA methylation, methyl CpG binding protein 2, microRNA, irradiation and metabolism that influence hedgehog signaling pathway transduction. These findings identify the hedgehog pathway as a potentially important for biomarker development and therapeutic targets in liver fibrosis. Future studies are needed in order to find safer and more effective hedgehog-based drugs.