Alteration of angiogenesis in Helicobacter heilmannii-induced mucosa-associated lymphoid tissue lymphoma: interaction with c-Met and hepatocyte growth factor

Clinicopathologic analysis of gastric mucosa-associated lymphoid tissue lymphoma with or without c-Met expression

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach is mainly associated with Helicobacter pylori infection, and H. pylori eradication therapy is often effective. However, 20-30% of the cases of MALT lymphoma are resistant to the eradication therapy, and translocation of the API2-MALT1 gene is often found in these cases. Most cases without translocation of API2-MALT1 are localized to the stomach, whereas some cases with this translocation are a more advanced stage of MALT lymphoma that spreads to other organs. The c-Met receptor is a prognostic factor involved in infiltration and metastasis in many malignant tumors, including gastric, pancreatic, lung, and kidney cancer. In the present study, the expression of c-Met in 43 cases of gastric MALT lymphomas was immunohistochemically examined and compared with clinicopathological factors. To elucidate the significance of c-Met in MALT lymphoma, the expression intensity of c-Met in 22 API2-MALT1 translocation-positive and 21 API2-MALT1 translocation-negative cases was scored, compared, and examined. The immunohistochemistry analysis revealed strong staining for c-Met in 21 API2-MALT1 translocation-positive cases and in 1 translocation-negative case (P = 0.00). This result indicates the relationship between strong expression of c-Met and the progression of MALT lymphoma with API2-MALT1 gene translocation.

Hepatocyte growth factor in physiology and infectious diseases

Hepatocyte growth factor (HGF) is a pleiotropic cytokine composed of an α-chain and a β-chain, and these chains contain four kringle domains and a serine protease-like structure, respectively. The receptor for HGF was identified as the c-met proto-oncogene product of transmembrane receptor tyrosine kinase. HGF-induced signaling through the receptor Met provokes dynamic biological responses that support morphogenesis, regeneration, and the survival of various cells and tissues, which includes hepatocytes, renal tubular cells, and neurons. Characterization of tissue-specific Met knockout mice has further indicated that the HGF-Met system modulates immune cell functions and also plays an inhibitory role in the progression of chronic inflammation and fibrosis. However, the biological actions that are driven by the HGF-Met pathway all play a role in the acquisition of the malignant characteristics in tumor cells, such as invasion, metastasis, and drug resistance in the tumor microenvironment. Even though oncogenic Met signaling remains the major research focus, the HGF-Met axis has also been implicated in infectious diseases. Many pathogens try to utilize host HGF-Met system to establish comfortable environment for infection. Their strategies are not only simply change the expression level of HGF or Met, but also actively hijack HGF-Met system and deregulating Met signaling using their pathogenic factors. Consequently, the monitoring of HGF and Met expression, along with real-time detection of Met activation, can be a beneficial biomarker of these infectious diseases. Preclinical studies designed to address the therapeutic significance of HGF have been performed on injury/disease models, including acute tissue injury, chronic fibrosis, and cardiovascular and neurodegenerative diseases. Likewise, manipulating the HGF-Met system with complete control will lead to a tailor made treatment for those infectious diseases.

The role of HGF/c-MET signaling pathway in lymphoma

Inappropriate activation of c-mesenchymal-epithelial transition (MET), the receptor tyrosine kinase (RTK) for hepatocyte growth factor (HGF), has been implicated in tumorigenesis and represented a promising therapeutic target for developing anticancer agents. In contrast to other solid tumors, there are limited data describing the functional role of HGF/c-MET signaling pathway in lymphoma. In the current review, we summarize recent findings about the expression, cellular mechanisms/functions, and therapeutic application of HGF/c-MET in different types of lymphoma, especially B cell lymphoma, T and NK cell lymphoma, and Hodgkin lymphoma. We also discuss the existing problems and future directions about studying the HGF/c-MET pathway in lymphoma cells.

Emerging treatments in neurogastroenterology: Acotiamade, a novel treatment option for functional dyspepsia

BACKGROUND

Acotiamide hydrochloride (Z-338) is a new therapeutic agent for functional dyspepsia (FD). In 2013, the use of acotiamide was approved by the Japanese health insurance system.

PURPOSE

The aim of this review is to summarize the present staus of basic and clinical approach to acotiamide for the treatment of functional dyspepsia. The agent inhibits acetylcholinesterase in vitro and enhances muscle motility ex vivo. In phase-II studies, 100 mg three times daily (t.i.d.) was determined to be the optimal dose for the treatment of FD. In phase-III studies, overall treatment efficacy (OTE) was significantly better in the acotiamide group (52.2%) than in the placebo group (34.8%). However, the mechanism of its efficacy needs to be further elucidated. Acotiamide effectively improved FD symptoms, particularly postprandial distress syndrome symptoms, without causing major adverse effects.

The Other Helicobacters

In the past year, a substantial number of (putative) novel Helicobacter species have been described, including Helicobacter himalayensis colonizing the Himalayan marmot and Helicobacter apodemus, colonizing the Korean striped field mouse. In addition, a putative novel gastric Helicobacter species was identified in wild gorillas and chimpanzees, for which the name "Candidatus H. homininae" was proposed. A high incidence of gastric non-H. pylori Helicobacter infection was described in China and multiple case reports have described the involvement of enterohepatic Helicobacter species, especially Helicobacter cinaedi, in a wide range of diseases. Several studies in rodent models further elucidated the mechanisms underlying the development of gastric mucosa-associated lymphoid tissue lymphoma during infection with gastric non-H. pylori Helicobacters. The effects of infection with gastric Helicobacters on the development of neuroinflammation were investigated and several enterohepatic Helicobacter species were shown to affect the composition of the gut microbiota, to influence vaccine efficiency as well as the progression of cancer in distant sites of the body.