Silencing of MAP4K4 by short hairpin RNA suppresses proliferation, induces G1 cell cycle arrest and induces apoptosis in gastric cancer cells.

Gastric cancer (GC) is the second most common cause of cancer­associated mortality worldwide. Previous studies suggest that mitogen­activated protein kinase kinase kinase kinase isoform 4 (MAP4K4) is involved in cancer cell growth, apoptosis and migration. In the present study, bioinformatics analysis and reverse transcription­quantitative polymerase chain reaction were performed to determine if MAP4K4 was overexpressed in GC. The knockdown of MAP4K4 by RNA interference in GC cells markedly inhibited cell proliferation, which may be mediated by cell cycle arrest in the G1 phase. The silencing of MAP4K4 also induced cell apoptosis by increasing the ratio of Bax/Bcl­2. In addition, Notch signaling was markedly reduced by MAP4K4 silencing. The results of the present study suggested that inhibition of MAP4K4 may be a therapeutic strategy for GC.

Effect of RTKN on progression and metastasis of colon cancer in vitro.

Like many epithelial-derived cancers, colon cancer results from a multistep tumorigenic process. However, the detailed mechanisms involved in colon cancer formations are poorly characterized. In the present study, we investigated the role of RTKN in colon cancer and explored underlying mechanisms. The results showed that RTKN expression was significantly increased in colon cancer tissues when compared with the adjacent tissues of patients in Shanghai People's hospital and in TCGA independent dataset. Furthermore, silencing of RTKN inhibited cell proliferation, migration, invasion, and arrested cell cycle at G1 phase in LOVO cells. Bioinformatics analysis demonstrated that DNA replication and cell cycle were involved in the regulation of RTKN. MCM2/3/5, CDK1/2 and PCNA expression had a direct relationship with the reduction of RTKN. RTKN could affect the proliferation and metastasis of colon cancer by reducing expression of MCM2/3/5, CDK1/2 and PCNA, suggesting that RTKN was a potential target for treating colon cancer.

Ponicidin induces apoptosis via JAK2 and STAT3 signaling pathways in gastric carcinoma.

Ponicidin has a variety of biological effects such as immunoregulatory and anti-inflammatory functions as well as anti-viral functions especially in the upper respiratory tract infection. This study was aimed to elucidate the antitumor effect of ponicidin in gastric carcinoma MKN28 cells and the possible molecular mechanism involved. Cell viability was measured by the Cell Count Kit-8 (CCK8). Cell apoptosis was assessed by flow cytometry as well as cell cycle and reactive oxygen species (ROS) analysis. Western blot analysis was used to detect the active form of caspase-3 as well as Bax and B-cell lymphoma-2 (Bcl-2) expressions after cells were treated with different concentrations of ponicidin. The results revealed that ponicidin could inhibit the growth of MKN28 cells significantly in both a time- and dose-dependent manner. The cell cycle was blocked and ROS generation was increased after the cells were treated with ponicidin. Bcl-2 expression was down-regulated remarkably while Bax expression and the active form of caspase-3 were increased after apoptosis occurred. We therefore conclude that ponicidin exhibited significant growth inhibition of gastric carcinoma cell line MKN28 and induced apoptosis of MKN28 cells via the signaling pathway regulated by Janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3). Ponicidin may serve as a potential therapeutic agent for gastric carcinoma.

[Changes of tight junction claudin-1,-3,-4 protein expression in the intestinal mucosa in patients with irritable bowel syndrome].

OBJECTIVE: To investigate the changes of intestinal mucosal tight junction proteins claudin-1, -3, -4 in patients with irritable bowel syndrome (IBS), and elucidate its possible role in the bowel evacuation habit changes and formation in these patients. METHODS: Western blotting was employed to determine tight junction protein claudin-1,-3,-4 levels in the intestinal mucosa of patients in the control group, diarrhea-predominant IBS (D-IBS) group and constipation-predominant IBS (C-IBS) group. RESULTS: Compared with the control group, D-IBS patients showed significantly decreased claudin-1 protein levels in both the small intestinal and colonic mucosae (P<0.05), whereas C-IBS patients had significantly elevated claudin-1 protein levels (P<0.05). No significant difference was found in claudin-3 protein expression in the both small intestinal and colonic mucosae between the D-IBS group and the control group (P>0.05), but claudin-3 protein level was shown to increase significantly in C-IBS patients (P<0.05). Claudin-4 protein followed the same pattern of alteration as claudin-1. CONCLUSION: Down-regulated claudin-1 and -4 expressions can be associated with bowel evacuation habit changes and formation in patients with D-IBS, but up-regulated claudin-1, -3 and -4 expressions may relate to such bowel changes in patients with C-IBS.

[Changes in tight junction of intestinal mucosa in patients with irritable bowel syndrome: a study with tracing electron microscope].

OBJECTIVE: To investigate the presence of tight junction (TJ) changes of the intestinal mucosa, and elucidate the possible mechanism for changes in bowel evacuation in patients with irritable bowel syndrome (IBS). METHODS: In 10 normal control subjects, 10 patients with constipation predominant IBS (C-IBS) and 10 with diarrhea predominant IBS (D-IBS), biopsies were taken from the terminal ileum and ascending colon. Lanthanum nitrate tracing electron microscope and cytochemical technique were employed to observe TJ changes in the intestinal mucosa. RESULTS: Like the control subjects, C-IBS patients had normal TJ structure in the intestinal mucosa, whereas D-IBS patients exhibited some abnormalities in TJ structure either in their terminal ileum (7 in 10) or ascending colon (8 in 10), revealed by TJ gap widening with lanthanum nitrate extravasation into the surrounding tissue. Such changes were also observed in 3 of the 4 patients with a history of acute infectious diarrhea. CONCLUSION: The changes in the intestinal mucosal TJ structure and function might contribute to altered bowel evacuation in patients with irritable bowel syndrome.

Effect of change in an inhibitory neurotransmitter of the myenteric plexus on the pathogenetic mechanism of irritable bowel syndrome subgroups in rat models.

OBJECTIVE: In order to investigate the effect of change in an inhibitory neurotransmitter of the myenteric plexus on irritable bowel syndrome (IBS) subgroups, the amounts of nitric oxide (NO) in constipation-predominant (C-IBS) and diarrhea-predominant (D-IBS) IBS models in rats were studied. METHODS: The D-IBS model was created in rats by intracolonic instillation of acetic acid and by restraint stress. The D-IBS control group underwent intracolonic instillation with saline instead. The C-IBS model was created in rats by gastric instillation of 0-4 degrees C cool water daily for 14 days. The C-IBS control group underwent gastric instillation with saline instead. A blank control group was also made. Viscerosomatic sensitivity was assessed with electromyographic (EMG). Abdominal contractions induced by distension of a colonically inserted balloon (0-1.6 mL) was recorded in rats by implanting electrodes in the abdominal external oblique muscle. An India ink gastric instillation experiment was used to detect the bowel movement and fecal pellets formation. Histological analysis of colonic tissue was performed. Nicotinamide dinucleotide phosphate (NADPH)-diaphorase staining was used to detect positive NO neurons in the myenteric plexus. RESULTS: When the balloon was distended by high volume, there were significantly more contractions of abdominal muscle in D-IBS compared with C-IBS and the control groups (P < 0.05). When the balloon was distended by low volume, there were significantly fewer contractions of abdominal muscle in C-IBS compared with D-IBS and the control groups (P < 0.05). The wet weight and water content of the feces expelled by the rats in the C-IBS and the C-IBS control groups were significantly lower than those in the blank control group (P < 0.05). The time before the first black stool in the C-IBS group was significantly longer than that in the blank control group and C-IBS control group (P < 0.05). Histological analysis of the colon showed no colonic inflammation in any group. The number of NO-positive neurons in the C-IBS group was significantly greater than in the D-IBS and control groups (P < 0.01), although there was no significant difference in the number of neurons between the D-IBS and the control groups (P > 0.05). CONCLUSIONS: Enhanced inhibitory neurotransmitter NO in the myenteric plexus of the colon is related to IBS subgroups, visceral sensitivity and motility dysfunction. The results reveal that NO plays a role in the pathogenetic mechanism of IBS subgroups.