He-Sheng Luo

Phosphoinositide 3‐kinase/Akt pathway plays an important role in chemoresistance of gastric cancer cells against etoposide and doxorubicin induced cell death

The major obstacle to successful treatment of gastric cancer is chemotherapy resistance. Our study was designed to investigate the role of phosphoinositide 3‐kinase (PI3K)/Akt pathway in the development of chemoresistance in gastric cancer. In the present study, elevated Akt expression and Akt phosphorylation (Ser 473), as well as decreased PTEN expression were observed in 28 cases of gastric cancer tissues. Etoposide and doxorubicin stimulated Akt and PI3K activities in 2 gastric cancer cell lines (BGC‐823 and SGC‐7901), and the activities were concentration and time‐dependent. Up‐regulation of PTEN expression in BGC‐823 cells by PEAK8‐PTEN transient transfection obviously decreased the basal and anticancer drugs induced Akt activities, then sensitized BGC‐823 cells to etoposide and doxorubicin. Pretreatment of BGC‐823 and SGC‐7901 cells with wortmannin, a PI3K inhibitor, attenuated cellss resistance to etoposide and doxorubicin. In addition, pretreatment of wortmannin blocked etoposide and doxorubicin induced IkappaB‐α degradation, NFkappaB activation, phosphorylation of Akt, MDM‐2 and forkhead transcription factors. Wortmannin pretreatment also promoted the accumulation of p27/Kip, but inhibited the Mcl‐1 expression. Furthermore, wortmannin promoted etoposide and doxorubicin induced caspase‐3, caspase‐9 activation and poly ADP‐ribose polymerase cleavage. Taken together, the observations indicate the PI3K/Akt pathway plays an important role in the chemoresistance of gastric cancer cells. A new strategy for combined chemotherapy of gastric cancer should be designed to more specifically block PI3K/Akt pathway and then decrease the amount of resistant cells.

Increased Expression of RelA/Nuclear Factor-κB Protein Correlates with Colorectal Tumorigenesis

Objective: To identify the role of RelA/nuclear factor-ĸB, an important inhibitor of apoptosis in colorectal tumorigenesis, we examined the expression of RelA in normal colorectal mucosa (n = 10), colorectal adenomas (n = 30) and colorectal adenocarcinomas (n = 30). Furthermore, the association of RelA expression with tumor cell apoptosis, proliferation, and expression of Bcl-2/Bcl-xL was also studied. Methods: Paraffin sections were stained with monoclonal antibodies directed against RelA, Bcl-2, Bcl-xL, and Ki-67 to assess protein expression patterns in normal, adenomatous and colon cancer tissue. Apoptotic cells were detected by terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labeling (TUNEL) using an in situ detection kit. Results: The results of immunohistochemical staining revealed that expression of RelA, Bcl-2, Bcl-xL, and Ki-67 labeling index (LI) significantly increased in the transition from adenoma with low dysplasia to adenocarcinoma. This transition was associated with a significant decrease in the apoptotic index (AI) and a significant increase in the Ki-67 LI. The expression of RelA correlated inversely with the AI and correlated positively with the expression of Bcl-2, Bcl-xL, and Ki-67 LI in the transition from low-grade dysplasia to adenocarcinoma. Conclusion: Our results suggest that increased expression of RelA/nuclear factor-ĸB plays an important role in the transition from colorectal adenoma with low-grade dysplasia to adenocarcinoma in the pathogenesis of colon cancer in humans.

Melatonin Reduces Inflammatory Injury Through Inhibiting NF-κB Activation in Rats With Colitis

Proinflammatory mediators are important in the pathogenesis of IBD, which are regulated by activation of NF-κB. The aim of this study was to investigate whether melatonin reduces inflammatory injury and inhibits proinflammatory molecule and NF-κB in rats with colitis. Rat colitis model was established by TNBS enema. NF-κB p65, TNF-α, ICAM-1, and IκBαin colon tissue were examined by immunohistochemistry, EMSA, RT-PCR, and Western blot analysis. Expression of proinflammatory molecule and activation of NF-κB were upregulated and IκB level decreased in rats with colitis. Melatonin reduces colonic inflammatory injury through downregulating proinflammatory molecule mediated by NF-κB inhibition and blockade of IκBα degradation.

The effects of acetylsalicylic acid on proliferation, apoptosis, and invasion of cyclooxygenase-2 negative colon cancer cells

Background Acetylsalicylic acid (ASA, aspirin), the most common nonsteroidal anti‐inflammatory drug (NSAID), has been shown to have a protective effect against the incidence and mortality of colorectal cancer. However, the mechanism of its anticancer function remains unclear. The aim of this study was to determine the effects of acetylsalicylic acid on proliferation, apoptosis, and invasion in human cyclooxygenase‐2 (COX‐2) negative colorectal cancer cell lines.

Increased abundance of cyclooxygenase-2 correlates with vascular endothelial growth factor-A abundance and tumor angiogenesis in gastric cancer

To understand the role of cyclooxygenase-2 (COX-2) in gastric cancer, we examined the abundance of COX-2, vascular endothelial growth factor-A (VEGF-A), and CD34 in 45 surgically resected human gastric cancers and paired normal gastric mucosa by immunohistochemical analysis. In addition, the message RNA (mRNA) expression of COX-2 and VEGF-A was evaluated in ten fresh surgically resected human gastric cancers and paired normal gastric mucosas using semi-quantitative reverse transcriptional polymerase chain reaction analysis. Our results confirmed an increased abundance of COX-2 and VEGF-A, and the microvessel density, which was assessed by CD34 abundance, in gastric cancer tissues compared with normal paired mucosa. Abundance of COX-2 and VEGF-A was significantly associated with tumor-node-metastasis (TNM) stage (P<0.05) and lymph node metastasis (P<0.001). In addition, abundance of VEGF-A associates with distance metastasis. A significant correlation was found between COX-2 and VEGF-A abundances (P<0.001). Both abundance of COX-2 and VEGF-A were significantly correlated with microvessel density (P<0.001, respectively). In six of ten cancerous tissues and in one of ten paired normal mucosas, the mRNA expression of COX-2 and VEGF-A was detected in the same specimen. In one other cancerous tissue, only COX-2 mRNA was detected. This study indicates that COX-2 is related to tumor angiogenesis in gastric cancer. VEGF-A might play a main role in the COX-2 angiogenic pathway.

Therapeutic Effects and Molecular Mechanisms of Ginkgo Biloba Extract on Liver Fibrosis in Rats

Oxidative stress can be implicated as a cause of liver fibrosis. In this sense, Ginkgo Biloba Extract (EGB), an antioxidant, may be beneficial in restraining liver fibrosis. The aim of this study was to evaluate the effects of EGB on experimental liver fibrosis. Rat liver fibrosis was induced by intraperitoneal injection of carbon tetrachloride (CCl4) twice a week for 8 weeks. Three groups of rats received EGB (0.25, 0.5 and 1.0 g/kg, respectively) by stomach everyday. CCl4 administration induced liver fibrosis, which was inhibited by EGB in a dose-dependent manner. The histopathologic score of fibrosis, liver function and the levels of plasma hyaluronic acid (HA) and laminin (LN) were significantly improved in rats treated with CCl4 + EGB, compared with those treated with CCl4 only (p < 0.01 or p < 0.05). The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were notably elevated, while malondialdehyde (MDA) content was significantly decreased in the rats treated with CCl4 + EGB (p < 0.01 or p < 0.05). Inhibition of hepatic stellate cell (HSC) activation and nuclear factor kappaBP65 (NF-kappaBP65) expression was demonstrated in the livers of EGB-treated rats. The activation of NF-kappaB was significantly suppressed in EGB-treated rats determined by electrophoretic mobility shift assay (EMSA). Furthermore, EGB reduced expressions of transforming growth factor-beta1 (TGF-beta1) and collagen I mRNA. In conclusion, EGB is able to ameliorate liver injury and prevent rats from CCl4-induced liver fibrosis by suppressing oxidative stress. This process may be related to inhibiting the induction of NF-kappaB on HSC activation and the expression of TGF-beta1.

The therapeutic effect of recombinant human trefoil factor 3 on hypoxia-induced necrotizing enterocolitis in immature rat

Trefoil peptides are a new class of regulatory peptides involved in mucosal protection and repair in the gastrointestinal tract. Among them, trefoil factor 3 (TFF3) (intestinal trefoil factor) is known to be cytoprotective in the gut. The aim of this study was to determine the effect of recombinant human trefoil factor 3 (rhTFF3) on hypoxia-induced necrotizing enterocolitis (NEC) in immature rats. In the present study, thirty-two 1-day-old Wistar rat pups were randomly divided into four groups. Group 1 served as nonhypoxic controls. Group 2 rats were subjected to hypoxia reoxygenation (H/O) and then were returned to their mothers. Groups 3 and 4 rats were subjected to H/O, were returned to their mothers, and were treated with rhTFF3 intraperitoneally (0.5 mg) and subcutaneously (0.2 mg), respectively, for the next 3 days. All animals were killed on day 4, and intestine specimens were obtained to determine the histological changes, tissue level of interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-alpha), malondialdehyde (MDA), prostaglandin E2 (PGE2), tromboxane B2 (TXB2), and nitric oxide (NO). In addition, the effects of rhTFF3 on abundance of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) were also investigated. In neonatal NEC (group 2), necrosis of villi and crypts and, in some cases, transmural necrosis was observed under light microscopy. Tissue level of interleukin-8, tumor necrosis factor-alpha, malondialdehyde, prostaglandin E2, tromboxane B2, and nitric oxide were significantly higher than group 1. In addition, abundance of inducible nitric oxide synthase and cyclooxygenase 2 was markedly increased. In groups 3 and 4, only very slight intestinal injury was observed. The tissue level of interleukin-8, tumor necrosis factor-alpha, malondialdehyde, prostaglandin E2, tromboxane B2, and nitric oxide were significantly decreased in comparison to the group 2. Meanwhile, the abundance of inducible nitric oxide synthase and cyclooxygenase 2 was also marked decreased in comparison to group 2. The current study suggests a therapeutic role of TFF3 in an experimental model of NEC. Our findings may open a new insight into the treatment of NEC in newborns.

Enhanced expression of cholecystokinin‐2 receptor promotes the progression of colon cancer through activation of focal adhesion kinase

Focal adhesion kinase (FAK) is suggested to be intimately involved in the progression of malignancies. Our previous research has demonstrated that activation of cholecystokinin‐2 receptor (CCK2R) by gastrin stimulates a rapid activation of FAK pathway in human colon cancer cells. The purpose of this study is to determine the role of CCK2R and FAK in the progression of colon cancer. In this study, matched tissue samples of primary colon cancer and adjacent normal colon mucosa from the same patient were collected from 45 patients with colon cancer undergoing surgical resection. The gastrin expression was detected using reverse transcription polymerase chain reaction (RT‐PCR). The CCK2R expression was examined by in situ hybridization and RT‐PCR. The expression of FAK and phosphorylated FAK at tyrosine 397 (phospho‐FAK) were detected using immunohistochemistry and immunoblotting. Colo320 and SW787, 2 colon cancer cell lines with or without CCK2R expression, were recruited in this study. Antisense oligonucleotide of FAK was used to block the expression of FAK. Invasiveness and motility of colon cancer cells were detected by Boyden chamber. In this series, enhanced expression of gastrin, CCK2R, FAK and phospho‐FAK were observed in colon cancer tissues. CCK2R expression correlated with expression of phospho‐FAK. Coexpression of CCK2R and phospho‐FAK associated with invasion and lymph node metastasis. Increased invasion and motility was induced by gastrin in Colo320 cells. Overexpression of CCK2R by stable transfection of CCK2R plasmid amplified this increase and incubation with 1 μM L‐365,260, a specific CCK2R antagonist, completely inhibited the effect of gastrin. FAK antisense largely blocked the increase of invasion and motility in Colo320 cells. Our data represent the evidence for the CCK2R regulating invasion and motility of colon cancer cells, and support a role of CCK2R in the progression of colon cancer. FAK play a critical role in this CCK2R‐mediated effect.

Increased expression of nuclear factor-κB/RelA is correlated with tumor angiogenesis in human colorectal cancer

Background and aimsRecent studies have shown that nuclear factor-κ B/RelA (NF-κ B/RelA) is involved in tumor angiogenesis. This study examined whether NF-κ B/RelA expression is associated with vascular endothelial growth factor (VEGF) expression and microvessel density in human colorectal cancer.Materials and methodsTen specimens from normal colorectal mucosa and 52 colorectal adenocarcinomas were obtained by surgery or endoscopy. Immunohistochemical expression of NF-κ B/RelA, VEGF, and CD34 was detected on paraffin-embedded tissue sections.ResultsNF-κ B/RelA and VEGF were significantly overexpressed and associated with microvessel density in colorectal cancer. A significant association was found between NF-κ B/RelA and VEGF expression. Clinicopathological features were not correlated with NF-κ B/RelA, VEGF expression, or microvessel density.ConclusionOur results suggest that increased expression of NF-κ B/RelA contributes to tumor angiogenesis in colorectal cancer. VEGF may play an important role in mediating the NF-κ B/RelA angiogenic pathway.

Ginkgo biloba extract alleviates liver fibrosis induced by CCl4 in rats

Abstract: Aims: To investigate the protective effect of Ginkgo biloba extract (GbE) on liver fibrosis induced by carbon tetrachloride (CCl4) in rats and expressions of transforming growth factor β1 (TGF‐β1) and collagen I during this period.