Therapeutic modulation of signal transduction pathways

Gastric cancer and Hedgehog signaling pathway: emerging new paradigms

Ever since its initial discovery in Drosophila, hedgehog signaling has been linked to foregut development, The mammalian genome expresses three Hedgehog paralogues, sonic hedgehog (Shh), Indian Hedgehog, and desert hedgehog. In the mucosa of the embryonic and adult foregut, Shh expression is the highest. It has now become clear that hedgehog signaling is of pivotal importance in gastric homeostasis. Aberrant activation of hedgehog signaling is associated with a range of pathological consequences including various cancers. Also in gastric cancer, clinical and preclinical data support a role of Hedgehog signaling in neoplastic transformation, and gastrointestinal cancer development, also through cancer stroma interaction. Technological advance are facilitating monitoring Hedgehog signaling broadening options for the more efficient screening of individuals predisposed to eventually developing gastric cancer and targeting Hedgehog signaling may provide opportunities for prophylactic therapy once atrophic gastritis develops. Nevertheless, convincing evidence that Hedgehog antagonists are of clinically useful in the context of gastric cancer is still conspicuously lacking. Here we analyze review the role of Hedgehog in gastric physiology and the potential usefulness of targeting Hedgehog signaling in gastric cancer.

Impact of Procyanidins from Different Berries on Caspase 8 Activation in Colon Cancer

Scope. The aim of this work is to identify which proapoptotic pathway is induced in human colon cancer cell lines, in contact with proanthocyanidins extracted from various berries. Methods and Results. Proanthocyanidins (Pcys) extracted from 11 berry species are monitored for proapoptotic activities on two related human colon cancer cell lines: SW480-TRAIL-sensitive and SW620-TRAIL-resistant. Apoptosis induction is monitored by cell surface phosphatidylserine (PS) detection. Lowbush blueberry extract triggers the strongest activity. When tested on the human monocytic cell line THP-1, blueberry Pcys are less effective for PS externalisation and DNA fragmentation is absent, highlighting a specificity of apoptosis induction in gut cells. In Pcys-treated gut cell lines, caspase 8 (apoptosis extrinsic pathway) but not caspase 9 (apoptosis intrinsic pathway) is activated after 3 hours through P38 phosphorylation (90 min), emphasizing the potency of lowbush blueberry Pcys to eradicate gut TRAIL-resistant cancer cells. Conclusion. We highlight here that berries Pcys, especially lowbush blueberry Pcys, are of putative interest for nutritional chemoprevention of colorectal cancer in view of their apoptosis induction in a human colorectal cancer cell lines.

Toll-like receptors are potential therapeutic targets in rheumatoid arthritis

Toll-like receptors (TLRs) are found on the membranes of pattern recognition receptors and not only play important roles in activating immune responses but are also involved in the pathogenesis of inflammatory disease, injury and cancer. Furthermore, TLRs are also able to recognize endogenous alarmins released by damaged tissue and necrosis and/or apoptotic cells and are present in numerous autoimmune diseases. Therefore, the release of endogenous TLR ligands plays an important role in initiating and driving inflammatory diseases. Increasing data suggest a role for TLR signaling in rheumatoid arthritis, which is an autoimmune disease. Although their involvement is not comprehensively understood, the TLRs signaling transducers may provide potential therapeutic targets.

Activated protein C, an anticoagulant polypeptide, ameliorates severe acute pancreatitis via regulation of mitogen-activated protein kinases

BACKGROUND

Our aim was to investigate the changes of mitogen-activated protein kinases (MAPKs) by activated protein C (APC) treatment in rats with severe acute pancreatitis (SAP), and relate them to changes in SAP severity, thus providing evidence for developing clinical therapies.

METHODS

Sprague-Dawley rats were given an intravenous injection of saline (SAP group), APC (50 microg/kg or 10 microg/kg), or CNI1493 just before SAP induction. One group of rats underwent a sham operation (control group). Experimental samples were harvested 16 h after SAP induction. The gene expression of pancreatic MAPKs was evaluated by cDNA microarrays. The mRNA and protein/phosphorylated protein levels of p38 MAPK, extracellular signal-regulated protein kinase (ERK) 1/2, and c-Jun N-terminal kinase (JNK) and the protein levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta were determined in pancreatic tissue. The severity of disease was evaluated by pancreatic histology, the pancreatic wet/dry weight ratio, and the serum amylase level.

RESULTS

In rats treated with APC (50 microg/kg) or CNI1493, the severity of pancreatitis and expression of pancreatic TNF-alpha and IL-1beta proteins were attenuated by the decreased expression and activity of p38 MAPK and JNK (vs. the SAP group, P < 0.01). The expression and activity of ERK1/2 were increased in APC-treated rats, especially in the group treated with APC 50 microg/kg (vs. the SAP or CNI1493-treated group, P < 0.01, respectively).

CONCLUSIONS

Inhibition of expression of pancreatic p38 MAPK and JNK and upregulation of ERK1/2 expression by APC treatment may protect against pancreatic injury, thus ameliorating severity of the disease.

Biological therapy in the management of recent-onset Crohn's disease: why, when and how?

Crohn's disease is a chronic inflammatory bowel disease that may involve any part of the gastrointestinal tract. Conventional therapy consists of corticosteroids, azathioprine or methotrexate, but the clinical management of Crohn's disease is significantly hampered by adverse effects. With the introduction of biological agents (such as infliximab), the goals of therapy have advanced, including induction of remission with bowel healing as well as reduction in the rate of complications, surgeries and mortality. Current therapy for moderate to severe Crohn's disease is based on 'step-up' algorithms, which initiate treatment with corticosteroids followed by immunomodulatory agents, and defer therapy with biological agents until patients become refractory to conventional therapeutics. Recently, it has been shown that induction therapy with infliximab and azathioprine in recent-onset Crohn's disease (i.e. 'top-down' approach) is superior to current step-up algorithms to induce clinical remission. The underlying molecular mechanisms responsible for these differences in clinical outcome remain to be defined. Experimental studies have demonstrated that corticosteroids are able to induce impaired apoptosis of immune cells, including T cells and dendritic cells, resulting in loss of tolerance and subsequent autoimmunity. Further research will have to determine whether corticosteroid therapy augments the mechanism of loss of tolerance in Crohn's disease, which could complicate future clinical management.

Specific inhibition of c-Raf activity by semapimod induces clinical remission in severe Crohn's disease

There is a substantial need for novel treatment strategies in Crohn's disease (CD), a chronic relapsing inflammatory disease of the gut. In an earlier study, we reported clinical efficacy of a 2-wk treatment with semapimod (CNI-1493) in 12 patients with therapy resistant CD. The aim of this study was to identify the cellular target underlying semapimod action. In vitro experiments with murine macrophages showed impaired MAPK signaling and decreased cytokine production due to semapimod treatment. In vitro kinase assays revealed c-Raf as a direct molecular target of semapimod, and semapimod did not affect b-Raf enzymatic activity. Immunohistochemistry performed on paired colon biopsies obtained from CD patients (n = 6) demonstrated increased expression of phospho-MEK, the substrate of Raf. Strikingly, phospho-MEK levels were significantly decreased in patients with a good clinical response to semapimod, but no decrease in phospho-MEK expression was observed in a clinically nonresponsive patient. In conclusion, this study identifies c-Raf as a molecular target of semapimod action and suggests that decreased c-Raf activity correlates with clinical benefit in CD. Our observations indicate that c-Raf inhibitors are prime candidates for the treatment of CD.