Yanglin Pan

miR-15b and miR-16 modulate multidrug resistance by targeting BCL2 in human gastric cancer cells

microRNAs are endogenous small noncoding RNAs that regulate gene expression negatively at posttranscriptional level. This latest addition to the complex gene regulatory circuitry revolutionizes our way to understanding physiological and pathological processes in the human body. Here we investigated the possible role of microRNAs in the development of multidrug resistance (MDR) in gastric cancer cells. microRNA expression profiling revealed a limited set of microRNAs with altered expression in multidrug‐ resistant gastric cancer cell line SGC7901/VCR compared to its parental SGC7901 cell line. Among the downregulated microRNAs are miR‐15b and miR‐16, members of miR‐15/16 family, whose expression was further validated by qRT‐PCR. In vitro drug sensitivity assay demonstrated that overexpression of miR‐15b or miR‐16 sensitized SGC7901/VCR cells to anticancer drugs whereas inhibition of them using antisense oligonucleotides conferred SGC7901 cells MDR. The downregulation of miR‐15b and miR‐16 in SGC7901/VCR cells was concurrent with the upregulation of Bcl‐2 protein. Enforced mir‐15b or miR‐16 expression reduced Bcl‐2 protein level and the luciferase activity of a BCL2 3′ untranslated region‐based reporter construct in SGC7901/VCR cells, suggesting that BCL2 is a direct target of miR‐15b and miR‐16. Moreover, overexpression of miR‐15b or miR‐16 could sensitize SGC7901/VCR cells to VCR‐induced apoptosis. Taken together, our findings suggest that miR‐15b and miR‐16 could play a role in the development of MDR in gastric cancer cells at least in part by modulation of apoptosis via targeting BCL2.

MiR-218 Inhibits Invasion and Metastasis of Gastric Cancer by Targeting the Robo1 Receptor

MicroRNAs play key roles in tumor metastasis. Here, we describe the regulation and function of miR-218 in gastric cancer (GC) metastasis. miR-218 expression is decreased along with the expression of one of its host genes, Slit3 in metastatic GC. However, Robo1, one of several Slit receptors, is negatively regulated by miR-218, thus establishing a negative feedback loop. Decreased miR-218 levels eliminate Robo1 repression, which activates the Slit-Robo1 pathway through the interaction between Robo1 and Slit2, thus triggering tumor metastasis. The restoration of miR-218 suppresses Robo1 expression and inhibits tumor cell invasion and metastasis in vitro and in vivo. Taken together, our results describe a Slit-miR-218-Robo1 regulatory circuit whose disruption may contribute to GC metastasis. Targeting miR-218 may provide a strategy for blocking tumor metastasis.

Cellular prion protein promotes invasion and metastasis of gastric cancer

Cellular prion protein (PrPc) is a glycosylphosphatidylinositol (GPI) ‐anchored membrane protein that is highly conserved in mammalian species. PrPc has the characteristics of adhesive molecules and is thought to play a role in cell adhesion and membrane signaling. Here we investigated the possible role of PrPc in the process of invasiveness and metastasis in gastric cancers. PrPc was found to be highly expressed in metastatic gastric cancers compared to nonmetastatic ones by immunohistochemical staining. PrPc significantly promoted the adhesive, invasive, and in vivo metastatic abilities of gastric cancer cell lines SGC7901 and MKN45. PrPc also increased promoter activity and the expression of MMP11 by activating phosphorylated ErK1/2 in gastric cancer cells. MEK inhibitor PD98059 and MMP11 antibody (Ab) significantly inhibited in vitro invasive and in vivo metastatic abilities induced by PrPc. N‐terminal fragment (amino acid 24–90) was suggested to be an indispensable region for signal transduction and invasion‐promoting function of PrPc. Taken together, the present work revealed a novel function of PrPc that the existence of N‐terminal region of PrPc could promote the invasive and metastatic abilities of gastric cancer cells at least partially through activation of MEK/ERK pathway and consequent transactivation of MMP11.—Pan, Y., Zhao, L., Liang, J., Liu, J., Shi, Y., Liu, N., Zhang, G., Jin, H., Gao, J., Xie, H., Wang, J., Liu, Z., Fan, D. Cellular prion protein promotes invasion and metastasis of gastric cancer. FASEB J. 20, E1205–E1215 (2006)

Reversal of the Malignant Phenotype of Gastric Cancer Cells by Inhibition of RhoA Expression and Activity

Purpose: The small GTPase RhoA has been implicated in the regulation of cell morphology, motility, and transformation, but the role of RhoA protein in the carcinogenesis of gastric cancer remains unclear. In the present study, we have analyzed the expression status of the RhoA protein in human gastric cancer cells and tissues and investigated the possible involvement of RhoA in regulating the malignant phenotype of gastric cancer cells. Experimental Design: RhoA expression was analyzed by immunohistochemistry and Western blot in gastric cancer tissues and cell lines. The RhoA-specific small interfering RNA (siRNA) vector was designed and constructed. We examined the role of RhoA in the malignant phenotype of gastric cancer cells by using siRNA knockdown and dominant-negative RhoA mutant suppression of endogenous RhoA activity. Results: RhoA was found frequently overexpressed in gastric cancer tissues and cells compared with normal tissues or gastric epithelial cells. RhoA-specific siRNA could specifically and stably reduce RhoA expression up to 90% in AGS cells. Both RhoA-specific siRNA and dominant-negative RhoA expressions could significantly inhibit the proliferation and tumorigenicity of AGS cells and enhance chemosensitivity of the cancer cells to Adriamycin and 5-fluorouracil. Conclusion: RhoA may play a critical role in the carcinogenesis of gastric cancer, and the interference of RhoA expression and/or activity could provide a novel avenue in reversing the malignant phenotype of gastric cancer cells.

Overexpression and significance of prion protein in gastric cancer and multidrug-resistant gastric carcinoma cell line SGC7901/ADR.

In our previous work, cellular prion protein (PrPc) was identified as an upregulated gene in adriamycin‐resistant gastric carcinoma cell line SGC7901/ADR compared to its parental cell line SGC7901. Here we investigate the expression of PrPc in gastric cancer and whether it was involved in multidrug resistance (MDR) of gastric cancer. We demonstrated that PrPc was ubiquitously expressed in gastric cancer cell lines and tissues. PrPc conferred resistance of both P‐glycoprotein (P‐gp)‐related and P‐gp‐nonrelated drugs on SGC7901, which was accompanied by decreased accumulation and increased releasing amount of adriamycin in PrPc‐overexpressing cell line. Inhibition of PrPc expression by antisense or RNAi technology could partially reverse multidrug‐resistant phenotype of SGC7901/ADR. PrPc significantly upregulated the expression of the classical MDR‐related molecule P‐gp but not multidrug resistance associated protein and glutathione S‐transferase pi. The PrPc‐induced MDR could be partially reversed by P‐gp inhibitor verapamil. PrPc could also suppress adriamycin‐induced apoptosis and alter the expression of Bcl‐2 and Bax, which might be another pathway contributing to PrPc‐related MDR. The further study of the biological functions of PrPc may be helpful for understanding the mechanisms of occurrence and development of clinical gastric carcinoma and PrPc‐related MDR and developing possible strategies to treat gastric cancer.

miR-206 inhibits gastric cancer proliferation in part by repressing cyclinD2.

In this study, we detected miR-206 expression in gastric cancer (GC) and further investigated its effects on GC cell growth in vitro and in vivo. miR-206 expression was found to be significantly decreased in 30 GC samples and GC cell lines by real time-PCR. Restoration of miR-206 reduced cell growth and colony forming ability in GC cells with G0/G1 cell cycle arrest. Further studies demonstrated that miR-206 could suppress GC cells proliferation at least partially through targeting the cyclinD2 (CCND2). Therefore, we provided evidence that miR-206 was a potential tumor suppressor and may be used as a therapeutic target for gastric cancer.

Telephone-based re-education on the day before colonoscopy improves the quality of bowel preparation and the polyp detection rate: a prospective, colonoscopist-blinded, randomised, controlled study

Background Despite advances in bowel preparation methods, the quality of bowel preparation in some patients undergoing colonoscopy remains unsatisfactory. The effect of telephone re-education (TRE) on the day before colonoscopy on the quality of bowel preparation and other outcome measures had not been studied. Methods A prospective colonoscopist-blinded study was conducted. All patients received regular instructions during a visit to discuss colonoscopy. Those scheduled for colonoscopy were randomly assigned to receive TRE on the day before colonoscopy (TRE group) for bowel preparation or no TRE (control group). The primary outcome was the rate of adequate bowel preparation. The secondary outcomes included polyp detection rate (PDR), non-compliance with instructions, and willingness to repeat bowel preparation. Results A total of 605 patients were randomised, 305 to the TRE group and 300 to the control group. In an intention-to-treat analysis of the primary outcome, adequate preparation was found in 81.6% vs 70.3% of TRE and control patients, respectively (p=0.001). PDR was 38.0% vs 24.7% in the TRE and control group, respectively (p<0.001). Among patients with successful colonoscopy, the Ottawa scores were 3.0±2.3 in the TRE group and 4.9±3.2 in the control group (p<0.001). Fewer patients who showed non-compliance with instructions were found in the TRE group (9.4% vs 32.6%, p<0.001). No significant differences were observed between the two groups with regard to willingness to have a repeat bowel preparation (p=0.409). Conclusions TRE about the details of bowel preparation on the day before colonoscopy significantly improved the quality of bowel preparation and PDR.

Cellular prion protein promotes proliferation and G1/S transition of human gastric cancer cells SGC7901 and AGS

The function of cellular prion protein (PrPC), the essential protein for the pathogenesis and transmission of prion diseases, is still largely unknown. The putative roles of PrPC are thought to be related to cell signaling, survival, and differentiation. In a previous study, we showed that PrPC was overexpressed in gastric cancer tissues. In the present report, we show that ectopic expression of PrPC could promote tumor‐igenesis, proliferation, and G1/S transition in gastric cancer cells. Furthermore, CyclinD1, a protein related to cell cycle, was shown to be significantly up‐regulated by PrPC at both mRNA and protein levels. PI3K/Akt pathway mediated above PrPC signal since PrPC increased the expression of phosphorylated Akt, and the specific inhibitor of Akt, LY294002, could markedly suppress growth of SGC7901 and transactivation of CyclinD1 induced by PrPC. Octapeptide repeat region played a vital role in this function, as deletion of this region abolished or reduced these effects. Collectively, this study demonstrates that overexpression of PrPC might promote the tumorigenesis and proliferation of gastric cancer cells at least partially through activation of PI3K/Akt pathway and subsequent transcriptional activation of CyclinD1 to regulate the G1/S phase transition, in which octapeptide repeat region might be an indispensable region.–Liang, J., Pan, Y., Zhang, D., Guo, C., Shi, Y., Wang, J., Chen, Y., Wang, X., Liu, J., Guo, X., Chen, Z., Qiao, T., Fan, D. Cellular prion protein promotes proliferation and G1/S transition of human gastric cancer cells SGC7901 and AGS. FASEB J. 21, 2247–2256 (2007)

Routine pre-procedural rectal indometacin versus selective post-procedural rectal indometacin to prevent pancreatitis in patients undergoing endoscopic retrograde cholangiopancreatography: a multicentre, single-blinded, randomised controlled trial.

BACKGROUND Rectal indometacin decreases the occurrence of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). However, the population most at risk and the optimal timing of administration require further investigation. We aimed to assess whether pre-procedural administration of rectal indometacin in all patients is more effective than post-procedural use in only high-risk patients to prevent post-ERCP pancreatitis. METHODS We did a multicentre, single-blinded, randomised controlled trial at six centres in China. Eligible patients with native papilla undergoing ERCP were randomly assigned in a 1:1 ratio (with a computer-generated list) to universal pre-procedural indometacin or post-procedural indometacin in only high-risk patients, with stratification by trial centres and block size of ten. In the universal indometacin group, all patients received a single dose (100 mg) of rectal indometacin within 30 min before ERCP. In the risk-stratified, post-procedural indometacin group, only patients at predicted high risk received rectal indometacin, immediately after ERCP. Investigators, but not patients, were masked to group allocation. The primary outcome was overall ocurrence of post-ERCP pancreatitis. The analysis followed the intention-to-treat principle. This study was registered with ClinicalTrials.gov, number NCT02002650. FINDINGS Between Dec 15, 2013, and Sept 21, 2015, 2600 patients were randomly assigned to universal, pre-procedural indometacin (n=1297) or risk-stratified, post-procedural indometacin (n=1303). Overall, post-ERCP pancreatitis occurred in 47 (4%) of 1297 patients assigned to universal indometacin and 100 (8%) of 1303 patients assigned to risk-stratified indometacin (relative risk 0·47; 95% CI 0·34-0·66; p<0·0001). Post-ERCP pancreatitis occurred in 18 (6%) of 305 high-risk patients in the universal group and 35 (12%) of 281 high-risk patients in the risk-stratified group (p=0·0057). Post-ERCP pancreatitis was also less frequent in average-risk patients in the universal group (3% [29/992]), in which they received indometacin, than in the risk-stratified group (6% [65/1022]), in which they did not receive the drug (p=0·0003). Other than pancreatitis, adverse events occurred in 41 (3%; two severe) patients in the universal indometacin group and 48 (4%; one severe) patients in the risk-stratified group. The most common adverse events were biliary infection (22 [2%] patients vs 33 [3%] patients) and gastrointestinal bleeding (13 [1%] vs ten [1%]). INTERPRETATION Compared with a risk-stratified, post-procedural strategy, pre-procedural administration of rectal indometacin in unselected patients reduced the overall occurrence of post-ERCP pancreatitis without increasing risk of bleeding. Our results favour the routine use of rectal indometacin in patients without contraindications before ERCP. FUNDING National Key Technology R&D Program, National Natural Science Foundation of China.

Elevated plasma osteopontin level is predictive of cirrhosis in patients with hepatitis B infection

Background:  Osteopontin (OPN) was shown to play an important role in the pathogenesis of various inflammatory and fibrotic processes and elevated in fibrotic liver of mouse model. However, the significance of OPN in hepatitis B virus (HBV)‐induced liver cirrhosis (LC) remains unclear and is therefore evaluated in this study.