Lycium barbarum polysaccharide alleviates DSS-induced chronic ulcerative colitis by restoring intestinal barrier function and modulating gut microbiota

PURPOSE

This study examined the protective effects and mechanism of Lycium barbarum polysaccharides (LBP) in the context of intestinal barrier function and intestinal microbiota in mice with dextran sulfate sodium (DSS)-induced chronic ulcerative colitis (UC).

METHODS

C57BL/6J male mice were assigned to a standard normal diet without DSS (control group), a normal diet with DSS (DSS group, 2% DSS given discontinuously for 3 weeks) or a normal diet supplemented with LBP (1% dry feed weight, LBP group, 2% DSS given discontinuously for 3 weeks) for a total of 8 weeks, at which point colonic tissues and caecal contents were collected.

RESULTS

LBP exerted a significant effect against colitis by increasing body weight, colon length, DAI and histopathological scores. LBP inhibited proinflammatory cytokines (IL-1β, IL-6, iNOS and TNF-α) expression, improved anti-inflammatory cytokine (IL-10) expression, promoted the expression of tight junction proteins (Occludin and ZO-1) via nuclear factor erythroid 2-related factor 2 (Nrf2) activation and decreased Claudin-2 expression to maintain the intestinal mucosal barrier. In addition, the abundances of some probiotics (Ruminococcaceae, Lactobacillus, Butyricicoccus, and Akkermansia) were decreased with DSS treatment but increased obviously with LBP treatment. And LBP reduced the abundance of conditional pathogens associated with UC (Mucispirillum and Sutterella). Furthermore, LBP improved the production of short-chain fatty acids (SCFAs), including acetic acid, propionic acid, butyric acid and isobutyric acid.

CONCLUSION

LBP can alleviate DSS-induced UC by regulating inflammatory cytokines and tight junction proteins. Moreover, LBP promotes probiotics, suppresses conditional pathogens and increases SCFAs production, showing a strong prebiotic effect.

Development and validation of a risk prediction score for the severity of acute hypertriglyceridemic pancreatitis in Chinese patients

BACKGROUND

The frequency of acute hypertriglyceridemic pancreatitis (AHTGP) is increasing worldwide. AHTGP may be associated with a more severe clinical course and greater mortality than pancreatitis caused by other causes. Early identification of patients with severe inclination is essential for clinical decision-making and improving prognosis. Therefore, we first developed and validated a risk prediction score for the severity of AHTGP in Chinese patients.

AIM

To develop and validate a risk prediction score for the severity of AHTGP in Chinese patients.

METHODS

We performed a retrospective study including 243 patients with AHTGP. Patients were randomly divided into a development cohort (n = 170) and a validation cohort (n = 73). Least absolute shrinkage and selection operator and logistic regression were used to screen 42 potential predictive variables to construct a risk score for the severity of AHTGP. We evaluated the performance of the nomogram and compared it with existing scoring systems. Last, we used the best cutoff value (88.16) for severe acute pancreatitis (SAP) to determine the risk stratification classification.

RESULTS

Age, the reduction in apolipoprotein A1 and the presence of pleural effusion were independent risk factors for SAP and were used to construct the nomogram (risk prediction score referred to as AAP). The concordance index of the nomogram in the development and validation groups was 0.930 and 0.928, respectively. Calibration plots demonstrate excellent agreement between the predicted and actual probabilities in SAP patients. The area under the curve of the nomogram (0.929) was better than those of the Bedside Index of Severity in AP (BISAP), Ranson, Acute Physiology and Chronic Health Evaluation (APACHE II), modified computed tomography severity index (MCTSI), and early achievable severity index scores (0.852, 0.825, 0.807, 0.831 and 0.807, respectively). In comparison with these scores, the integrated discrimination improvement and decision curve analysis showed improved accuracy in predicting SAP and better net benefits for clinical decisions. Receiver operating characteristic curve analysis was used to determine risk stratification classification for AHTGP by dividing patients into high-risk and low-risk groups according to the best cutoff value (88.16). The high-risk group (> 88.16) was closely related to the appearance of local and systemic complications, Ranson score ≥ 3, BISAP score ≥ 3, MCTSI score ≥ 4, APACHE II score ≥ 8, C-reactive protein level ≥ 190, and length of hospital stay.

CONCLUSION

The nomogram could help identify AHTGP patients who are likely to develop SAP at an early stage, which is of great value in guiding clinical decisions.

The effect of quality of segmental bowel preparation on adenoma detection rate

Background

The effectiveness in surveillance colonoscopy largely depends on the quality of bowel preparation. We aimed to investigate the quality of bowel preparation segmentally and its effect on Adenoma Detection Rate (ADR) and Advanced Adenoma Detection Rate (AADR) at corresponding bowel segments.

Methods

This is a single-centered and cross-sectional study. A consecutive of 5798 patients who underwent colonoscopy examination were included. Bowel preparation was evaluated based on Bowel Bubble Scale (BBS) in general and Boston Bowel Preparation Scale (BBPS) in each segment (right side, transverse and left side of colon) and total BBPS scores. The quality of bowel preparation was correlated with ADR and AADR.

Results

Four thousand nine hundred forty colonoscopies (14,820 bowel segments) were included in the final analysis. In which 30.9% scored 3, 57.5% scored 2, 11.2% scored 1 and 0.4% scored 0 on basis of BBPS. For each score, ADR were 10.8, 7.7, 4.9 and 3.2%, respectively; whereas AADR were 4.5, 2.8,1.8 and 1.6% (P < 0.05). 36.9% of the colonoscopies showed presence of minimal bubbles and 34.3% with no bubble. For bowels without bubbles and with a large amount of bubbles, ADR were 28.3 and 20.0% respectively; and AADR were 13.3 and 7.1% respectively.

Conclusions

Segmental bowels’ cleanliness and the amount of bubbles in bowels significantly affect ADR and AADR. The better the bowel preparation at each segment is and the less bubbles in the bowel there are, the higher ADR and AADR we got. We suggest repeating colonoscopy if any segment of the bowel preparation is poor, or if there is more bubbles, even if the total score of BBPS indicates good or fair bowel preparation.

[Changes of intestinal mucosal barrier in mice with chronic ulcerative colitis]

Objective: To study the damage and mechanism of intestinal mucosal barrier function in mice with ulcerative colitis induced by Dextran sulphate sodium (DSS). Methods: Mice models of chronic ulcerative colitis induced by DSS were established. The mice were completely randomized into normal control group and DSS group, 25 mice in each group. The body weight and colon length of the mice were monitored. The pathological examination of colon tissue was confirmed the success of the model and assessed the integrity of the colonic mucosal barrier; Evan's Blue's intestinal permeability analysis assessed the function of colon mucosal barrier; immunofluorescence staining and Western blot were used to evaluate the expression of intestinal mucosal barrier integrity-related proteins. Results: Compared with the normal control group, the DSS group had lower body weight [(25.6±0.7)g vs (23.5±0.7)g, t=2.14, P<0.05], and the colon length was shorter [(7.3±0.4)cm vs (5.6±0.2)cm, t=3.975, P<0.001]; colonic pathological results showed that the intestinal mucosa became thinner and part of the intestinal mucosa was defective; Evan's Blue instilled into the intestinal lumen was more abundant into the intestinal mucosa, and the optical density at 620 nm (OD(620))/colon tissue weight (g) was higher [(0.11±0.01) vs (0.15±0.01), t=4.174, P<0.05]; immunofluorescence and Western blot results showed lower expression of ZO-1, Claudin-1, and F-actin in colonic mucosa. Conclusion: The structure and function of intestinal mucosal barrier in DSS-induced chronic ulcerative colitis mice is impaired.

Efficacy and safety of using premedication with simethicone/Pronase during upper gastrointestinal endoscopy examination with sedation: A single center, prospective, single blinded, randomized controlled trial

BACKGROUND AND AIM

To investigate the efficacy and safety of premedication with simethicone/Pronase during esophagogastroduodenoscopy (EGD) with sedation.

METHODS

Six hundred and ten patients were randomly allocated to two groups based on type of premedication given. Premedication used in the control group was 10 mL lidocaine hydrochloride mucilage (LHM, N = 314) and premedication used in the intervention group was 80 mL simethicone/Pronase solution plus 10 mL lidocaine hydrochloride mucilage (SP/LHM, N = 296). EGD was done under sedation. Visibility scores, number of mucosal areas that needed cleansing, water consumption for cleansing, time taken for examination, diminutive lesions, pathological diagnosis, patients' gag reflex and oxygenation (pulse oximetry) were recorded.

RESULTS

SP/LHM has significantly lower total visibility score than LHM (7.978 ± 1.526 vs 6.348 ± 1.097, P < 0.01). During the procedure, number of intragastric areas that needed cleansing and amount of water consumed were significantly less in the SP/LHM than in the LHM group (P < 0.01). In SP/LHM (P = 0.01), endoscopy procedure duration was significantly longer. Although there was no significant difference in rate of detection of diminutive lesions between LHM and SP/LHM, the endoscopist carried out more biopsies in SP/LHM. This led to a higher rate of diagnosis of atrophic gastritis (P = 0.014) and intestinal metaplasia (P = 0.024). There was no significant difference in gag reflex (P = 0.604) and oxygenation during the endoscopy procedure for either group of patients.

CONCLUSION

Routine use of premedication with simethicone/Pronase should be recommended during EGD with sedation.

CacyBP/SIP nuclear translocation regulates p27Kip1 stability in gastric cancer cells

AIM: To investigate the mechanism of calcyclin binding protein/Siah-1 interacting protein (CacyBP/SIP) nuclear translocation in promoting the proliferation of gastric cancer (GC) cells.

METHODS: The effect of CacyBP/SIP nuclear translocation on cell cycle was investigated by cell cycle analysis. Western blot analysis was used to assess the change in expression of cell cycle regulatory proteins and proteasome-mediated degradation of p27Kip1. Co-immunoprecipitation (co-IP) analysis was performed to examine the binding of CacyBP/SIP with Skp1. A CacyBP/SIP truncation mutant which lacked the Skp1 binding site was constructed and fused to a fluorescent protein. Subsequently, the effect on Skp1 binding with the fusion protein was examined by co-IP, while localization of fluorescent fusion protein observed by confocal laser microscopy, and change in p27Kip1 protein expression assessed by Western blot analysis.

RESULTS: CacyBP/SIP nuclear translocation induced by gastrin promoted progression of GC cells from G1 phase. However, while CacyBP/SIP nuclear translocation was inhibited using siRNA to suppress CacyBP/SIP expression, cell cycle was clearly inhibited. CacyBP/SIP nuclear translocation significantly decreased the level of cell cycle inhibitor p27Kip1, increased Cyclin E protein expression whereas the levels of Skp1, Skp2, and CDK2 were not affected. Upon inhibition of CacyBP/SIP nuclear translocation, there were no changes in protein levels of p27Kip1 and Cyclin E, while p27Kip1 decrease could be prevented by the proteasome inhibitor MG132. Moreover, CacyBP/SIP was found to bind to Skp1 by immunoprecipitation, an event that was abolished by mutant CacyBP/SIP, which also failed to stimulate p27Kip1 degradation, even though the mutant could still translocate into the nucleus.

CONCLUSION: CacyBP/SIP nuclear translocation contributes to the proliferation of GC cells, and CacyBP/SIP exerts this effect, at least in part, by stimulating ubiquitin-mediated degradation of p27Kip1.

Difference of clinical characteristics of inflammatory bowel disease in different age groups of patients: A single-center analysis

AIM: To compare the characteristics of inflammatory bowel disease (IBD) in different age groups of patients to provide a vigorous basis for the clinical diagnosis and treatment of this disease.

METHODS: Five hundred and sixty-seven IBD patients treated at the General Hospital of Ningxia Medical University from January 2002 to December 2014 were divided into four groups according to the age at diagnosis: <17 years, 17-39 years, 40-59 years and >60 years. Gender, disease duration, clinical symptoms, extra-intestinal manifestations and complications were retrospectively compared in the four groups.

RESULTS: The hospitalization rate for each group showed an upward trend in recent years, and it was more common in men. The disease condition was more serious in the >60 age group than other groups, and most of the cases (85.39%) in the >60 age group belonged to the severe type. Crohn's disease activity index (CDAI) scores for CD patients in each group were similar, and most CD patients had a disease in remission or with moderate activity. With regard to the lesion location, UC in the <17 and 17-39 age groups was characterized by proctitis (100% and 53.25%, respectively), ascending colitis was more prevalent in the 40-59 age group (57.69%), and the whole colon was often involved in the >60 age group (79.78%). For CD, the terminal ileum inflammation was more common in the <17 and >60 age groups (50% and 46.67%, respectively), while colitis dominated in the 17-39 and 40-59 age groups (51.52% and 46.67%, respectively).

CONCLUSION: The <17 and >60 age groups have different clinical features and disease characteristics from those in the 17-39 and 40-59 age groups.

CacyBP/SIP nuclear translocation induced by gastrin promotes gastric cancer cell proliferation

AIM: To investigate the role of nuclear translocation of calcyclin binding protein, also called Siah-1 interacting protein (CacyBP/SIP), in gastric carcinogenesis.

METHODS: The expression of CacyBP/SIP protein in gastric cancer cell lines was detected by Western blot. Immunofluorescence experiments were performed on gastric cancer cell lines that had been either unstimulated or stimulated with gastrin. To confirm the immunofluorescence findings, the relative abundance of CacyBP/SIP in nuclear and cytoplasmic compartments was assessed by Western blot. The effect of nuclear translocation of CacyBP/SIP on cell proliferation was examined using MTT assay. The colony formation assay was used to measure clonogenic cell survival. The effect of CacyBP/SIP nuclear translocation on cell cycle progression was investigated. Two CacyBP/SIP-specific siRNA vectors were designed and constructed to inhibit CacyBP/SIP expression in order to reduce the nuclear translocation of CacyBP/SIP, and the expression of CacyBP/SIP in stably transfected cells was determined by Western blot. The effect of inhibiting CacyBP/SIP nuclear translocation on cell proliferation was then assessed.

RESULTS: CacyBP/SIP protein was present in most of gastric cancer cell lines. In unstimulated cells, CacyBP/SIP was distributed throughout the cytoplasm; while in stimulated cells, CacyBP/SIP was found mainly in the perinuclear region. CacyBP/SIP nuclear translocation generated a growth-stimulatory effect on cells. The number of colonies in the CacyBP/SIP nuclear translocation group was significantly higher than that in the control group. The percentage of stimulated cells in G1 phase was significantly lower than that of control cells (69.70% ± 0.46% and 65.80% ± 0.60%, control cells and gastrin-treated SGC7901 cells, P = 0.008; 72.99% ± 0.46% and 69.36% ± 0.51%, control cells and gastrin-treated MKN45 cells, P = 0.022). CacyBP/SIPsi1 effectively down-regulated the expression of CacyBP/SIP, and cells stably transfected by CacyBP/SIPsi1 were then chosen for further cellular assays. In CacyBP/SIPsi1 stably transfected cells, CacyBP/SIP was shown to be distributed throughout the cytoplasm, irregardless of whether they were stimulated or not. After CacyBP/SIP nuclear translocation was reduced, there had no major effect on cell proliferation, as shown by MTT assay. There had no enhanced anchorage-dependent growth upon stimulation, as indicated by colony formation in flat plates. No changes appeared in the percentage of cells in G0-G1 phase in either cell line (71.09% ± 0.16% and 70.86% ± 0.25%, control cells and gastrin-treated SGC7901-CacyBP/SIPsi1 cells, P = 0.101; 74.17% ± 1.04% and 73.07% ± 1.00%, control cells and gastrin-treated MKN45-CacyBP/SIPsi1 cells, P = 0.225).

CONCLUSION: CacyBP/SIP nuclear translocation promotes the proliferation and cell cycle progression of gastric cancer cells.

Clinical significance of expression of CacyBP/SIP in colorectal tissues

AIM: To detect the expression of CacyBP/SIP [Calcyclin (S100A6)-binding protein/Siah-1 interacting protein] in normal colorectal tissue, colorectal hyperplastic polyps, colorectal adenoma and colorectal cancer.

METHODS: Immunohistochemistry was used to analyze the expression of CacyBP/SIP in 10 normal colorectal tissue samples, 17 samples of colorectal hyperplastic polyps, 26 samples of colorectal adenomas and 50 samples of colorectal cancer. Four frozen tissue samples of colorectal cancer and adjacent noncancerous tissues were used in Western blot to detect CacyBP/SIP expression. Immunohistochemical results were compared against patient data and pathological analysis of tissue slices. Slices were assessed for associations with gender, age, degree of tumor differentiation and TNM stage.

RESULTS: CacyBP/SIP was detected in 0 (0/10) of normal tissue samples, 17.7% (7/26) of colorectal hyperplastic polyps, 26.9% (7/26) of colorectal adenomas, and 52% (26/50) of colorectal cancer tissues by immunohistochemistry. The expression of CacyBP/SIP in colorectal adenomas and colorectal cancer tissues was higher than that in the normal colon tissue and colorectal hyperplasic polyps (0 vs 26.9%, 0 vs 52%, 17.7% vs 26.9%, 17.7% vs 52%, P < 0.05 for all). The expression of CacyBP/SIP was also higher in cancerous tissue than in adjacent noncancerous colorectal tissue, as revealed by Western blot (P < 0.05). There was no association between CacyBP/SIP expression and patient age, gender, degree of tumor differentiation or TNM stage (P > 0.05 for all).

CONCLUSION: These results suggest that CacyBP/SIP may be involved in the progression of colorectal cancer.

Potent inhibition of human gastric cancer by HER2-directed induction of apoptosis with anti-HER2 antibody and caspase-3 fusion protein

BACKGROUND AND AIMS

HER2, an oncogene, has been found to be over-expressed in 10-40% of human gastric carcinomas. The aims of this study were to investigate if a fusion protein consisting of anti-HER2 sFv and constitutively active caspase-3 was capable of inducing apoptosis in HER2-expressing human gastric cancer cells and blocking the growth of human gastric cancer xenografts in nude mice.

METHODS

NIH3T3 cells stably transduced with the pcDNA3.1-HER-PE-CP3 recombinant plasmid containing a secretion signal, a single-chain anti-HER2 monoclonal antibody fragment, a Pseudomonas exotoxin A translocation domain and a constitutively active caspase-3 molecule were used to induce apoptosis in human gastric cancer cells both in vitro and in vivo. Immunofluorescence staining and western blotting were used to examine the expression of the recombinant protein HER-PE-CP3. Apoptosis was determined by flow cytometry and TUNEL assay.

RESULTS

Co-cultivation of HER-PE-CP3/ NIH3T3 with human gastric cancer cells led to internalisation of HER-PE-CP3 and apoptosis in HER2-expressing human gastric cancer cells but not in HER2-negative cancer cells. Inoculation of HER-PE-CP3/NIH3T3 in nude mice resulted in potent inhibition of human gastric cancer xenografts and much prolonged survival time of the tumour-bearing mice compared with the control. Significantly more apoptotic cells were detected in xenografts in mice receiving HER-PE-CP3/NIH3T3 than in control mice.

CONCLUSIONS

The HER-PE-CP3 chimeric molecule could induce selective apoptosis and potent growth inhibition of HER2-positive human gastric cancer cells and might represent a novel HER2-directed treatment option for human gastric cancer.

Expression and nucleus translocation of calcyclin binding protein in colon cancer cells

AIM: To verify expression and location of CacyBP/SIP in colon cancer cells, so to explore the role of CacyBP/SIP in colon cancer.

METHODS: The expression of CacyBP/SIP in the three colon cancer cell lines was detected using Western blot. The location of CacyBP/SIP in the colon cancer cell and location after stimulation by KCl, gastrin(10^-8 mol/L) were determined separately by indirect immunofluorescence. The change of Ca²⁺ concentration in the colon cancer cells stimulated by gastrin was detected by laser copolymerization focal.

RESULTS: CacyBP/SIP was detected in the HT29 and SW480 colon cancer cells and undetected in the Lovo colon cancer cells. CacyBP/SIP was located in the cytoplasm of colon cancer cells. After stimulation by KCl, CacyBP/SIP translocated into nucleus; after KCl was washed off, CacyBP/SIP was relocated in the cytoplasm. Upon stimulation by gastrin, CacyBP/SIP also translocated into the nucleus. Compared with the colon cancer cell without gastrin, intra-cellular Ca²⁺ concentration with gastrin was increased (25.33 ± 0.57 vs 21 ± 1, P < 0.05).

CONCLUSION: CacyBP/SIP is expressed in the colon cancer cells and located in the cytoplasm. CacyBP/SIP could translocate into the nucleus after increased intra-cellular Ca²⁺ concentration. These results suggest that CacyBP/SIP may be involved in the progression of colon cancer through nuclear translocation.

Effects of essential oil from Croton tiglium L. on intestinal transit in mice

AIM OF THE STUDY

Croton tiglium (Croton tiglium L., Euphorbiaceae) is widely used as a herb for treatment of gastrointestinal disturbances. Previous studies established its purgative and inflammational properties. The present study aimed to investigate the effects of Croton tiglium oil (CO) on intestinal transit in mice.

MATERIALS AND METHODS

Gastrointestinal transit in mice and contractile characteristics of isolated intestinal strips from mice were evaluated. Intestinal inflammation was confirmed by histological examination.

RESULTS

Low dose of CO increased the gastrointestinal transit of charcoal and barium meal as well as the production of fecal pellets in mice. In contrast, high dose exerted inhibitory effects. For normal colonic circular strips, both high and low dose of CO inhibited the contractile frequency. Low doses (0-20 microg/ml) of CO enhanced the phasic contractions, while high doses (>40 microg/ml) reduced them. Colonic longitudinal strips in CO-treated mice were less sensitive to electrical field stimulation than those in control mice. The contraction of colonic longitudinal, colonic and jejunal circular strips in CO-treated mice was more sensitive to atropine than that in control mice.

CONCLUSIONS

CO might modulate gastrointestinal motility and induce intestinal inflammation related to immunological milieu and motor activity. Our findings may highlight the ethno-medical uses of Croton tiglium on intestinal disorders.

[Prokaryotic expression and purification of RPS13 and preparation of polyclonal antibody against RPS13]

AIM

To construct prokaryotic expression plasmid of RPS13, express and purify the protein for the preparation of polyclonal antibody.

METHODS

RPS13 gene was amplified by reverse transcription polymerase chain reaction (RT-PCR) from the highly expressed cell of gastric multidrug cell SGC7901/VCR. After sequenced, the gene was cloned into the expression vector pET-28a(+) to construct RPS13 expression plasmid pET-28a(+)-RPS13. The expression plasmid was transformed into the E.coli BL21 and screened by ampiline, and then the E.coli BL21 containing the expression plasmid was induced by IPTG and the protein was purifed by Histag column. BALB/c mice were immunized by the immunogen His-RPS13. The titer was measured by ELISA and the polyclonal antibody was obtained.

RESULTS

The expression plasmid pET-28a(+)-RPS13 was constructed. The 19 kDa recombined protein was successfully expressed in the E.coli BL21 by IPTG for 3 hours, purified by Histag column and confirmed by SDS-PAGE and Western blot. The polyclonal anti-His-RPS13 antibody was obtained by immunizing the mice with RPS13 protein. RPS13 could be specifically recognized by the antibody based on Western blot.

CONCLUSION

RPS13 has bene expressed and purified successfully and polyclonal anti-His-RPS13 antibody has been prepared. Our study can be used for the preparation of monoclonal anti-His-RPS13 antibody and for further research of the function of the RPS13 protein in tumor.

Potential involvement of the cyclooxygenase-2 pathway in hepatocellular carcinoma-associated angiogenesis

Angiogenesis plays a crucial role in tumor development and growth. The present study was carried out to investigate the potential involvement of the cyclooxygenase-2 (Cox-2) pathway in the regulation of angiogenesis in hepatocellular carcinoma (HCC). We inhibited Cox-2 expression in HCC cell line HuH-7 by selective Cox-2 inhibitor (SC-58635) or Cox-2 siRNA. Conditioned media (CMs) from HuH-7 cells were used in angiogenic assays in vitro and in vivo. Compared with CMs from untreated and negative siRNA treated HuH-7 cells, CMs from SC-58635 and Cox-2 siRNA treated HuH-7 dramatically suppressed the proliferation, migration, and differentiation of human umbilical vein endothelial cells (HUVECs) in vitro and neovascularization in vivo. These inhibitory effects could be partially reversed by the addition of exogenous PGE2 to CMs. Furthermore, Cox-2 inhibition by SC-58635 resulted in PGE2 reduction accompanied by the down-regulation of four PGE2 receptor (EP receptor) subtypes. Treatment with SC-58635 led to the down-expression of proangiogenic factors such as VEGF, HGF, FGF2, ANGPT1 and ANGPT2 in HCC. An approximately 78% reduction of VEGF level has been found in the CM from SC-58635 treated HuH-7. Our results suggest an involvement of Cox-2 in the control of HCC-associated angiogenesis. PGE2 as a vital angiogenic factor may act directly on endothelial cells to promote HuH-7-stimulated angiogenic process. Moreover, Cox-2/PGE2/EP/VEGF pathway possibly also contributes to tumor angiogenesis in HCC. This study provides the rationale for clinical studies of Cox-2 inhibitors on the treatment or chemoprevention of HCC.

Apoptosis-inducing effect of recombinant Caspase-3 expressed by constructed eukaryotic vector on gastric cancer cell line SGC7901

AIM: To investigate the apoptosis-inducing effect of Caspases-3 expressed by constructed eukaryotic vector on gastric cancer cell line SGC7901.

METHODS: PCR was employed to amplify the sequences of both small and large subunits of Caspases-3. Its products were separately cloned into the Sma I site of pBluescript KS⁺ to generate both plasmids pBS/SS and pBS/LS. The small subunit fragment was excised from plasmid pBS/SS with BamH I and then inserted into the BamH I site of plasmid pBS/LS preceding that of the large subunit to yield plasmid pBS/Rev-Caspase-3. Rev-Caspase-3 cDNA was excised with Kpn I + Xba I and then subcloned into plasmid pcDNA3.1 (+) to construct Rev-Caspase-3 eukaryotic expression vector pcDNA/Rev-Caspase-3, which was used to transiently transfect SGC7901 cell line. Cell count, MTT assay and electron microscopy were used to confirm the antiproliferation and apoptosis-inducing effect of Rev-Caspase-3 expression on gastric cancer cells.

RESULTS: Plasmid pBS/Rev-Caspase-3 and eukaryotic expression vector pcDNA/Rev-Caspase-3 were successfully constructed. SGC7901 cells were transiently transfected by either pcDNA/Rev-Caspase-3 or pcDNA3.1 (+) for 24, 48, 72, and 96 h respectively. Cell growth was measured by cell count and MTT assay. In cell count assay, the cell numbers were 1.8 × 10⁶, 1.55 × 10⁶, 2.0 × 10⁶, and 3.1 × 10⁶ in the experimental group and 2.5 × 10⁶, 3.1 × 10⁶, 4.0 × 10⁶, and 5.7 × 10⁶ in the control group at 24, 48, 72 and 96 h respectively. The growth of SGC7901 cells was suppressed by Rev-Caspase-3 in a time-dependent manner (P < 0.05). The results of MTT assay were similar to that of cell count (P < 0.05). The characteristics of apoptosis such as chromatin condensation, crescent formation and margination were seen and more obvious with time in the given-experimental period in the experimental group, but not easily observed in the control group.

CONCLUSION: The expression of Rev-Caspase-3 by the constructed eukaryotic vector can significantly induce apoptosis of gastric cancer cell line SGC7901, which may exhibit a potential way in gastric cancer gene therapy.