Yu-Yun Wu

miR-1182 attenuates gastric cancer proliferation and metastasis by targeting the open reading frame of hTERT

In humans, telomerase reverse transcriptase (hTERT) determines the activity of telomerase. hTERT is an ideal anticancer target because it is universally expressed in cancer cells and plays a crucial role in carcinogenesis. In this study, we report the miR-1182-mediated post-transcriptional regulation of hTERT. Over-expression of miR-1182 in different gastric cancer cells decreased hTERT protein levels. Bioinformation and dual-luciferase assays revealed that miR-1182 modulated hTERT by binding to its open reading frame (ORF), and this miRNA recognizes elements in the nucleotide region between 2695 and 2719 of hTERT mRNA. Over-expression of hTERT by transfecting pIRES2-hTERT into U2OS cells was abolished by miR-1182, while pIRES2-hTERT-MT, in which miR-1182 target site was synonymously mutated, failed to respond to miR-1182. Further investigation revealed that miR-1182 inhibited gastric cancer proliferation and migration by targeting the ORF1 of hTERT. We also found that miR-1182 could attenuate the proliferative and metastatic potential of SGC-7901 cell in vivo. Moreover, we found a statistically significant inverse correlation between miR-1182 and hTERT protein levels in tissues from 42 gastric cancer patients. These data indicate that miR-1182 suppresses TERT, and thus it could be an effective target for the treatment of gastric cancer.

Hepatocyte growth factor (HGF) upregulates heparanase expression via the PI3K/Akt/NF-κB signaling pathway for gastric cancer metastasis.

Heparanase (HPA) is an endoglucuronidase that can promote the shedding of associated cytokines in several types of tumors. However, little is known about what controls the expression of HPA or its role in gastric cancer. In this study, we report for the first time that HGF regulates HPA expression to promote gastric cancer metastasis. In this study, HGF and HPA were found to be significantly expressed in 58 gastric cancer patients. High expression of both HGF and HPA was positively associated with TNM stage, invasion depth and poor prognosis. In MKN74 cells, exogenous HGF significantly increased HPA expression at both the mRNA and protein levels. Further study revealed that HGF first activated PI3K/Akt signaling. NF-κB signaling was activated downstream of PI3K/Akt and promoted HPA expression. However, when c-met, PI3K/Akt or NF-κB signal inhibitors were used, HPA expression was significantly decreased. All of these results indicate that HGF regulates HPA expression by PI3K/Akt and downstream NF-κB signaling. Using bioinformatics and the ChIP assay, p65 was observed to bind to the HPA promoter. Furthermore, HGF significantly induced tumor cell migration, whereas treatment with an NF-κB inhibitor decreased migration. Moreover, when HPA was overexpressed in MKN74 cells, migration was significantly enhanced, and the HGF concentration was increased. However, when HPA was down-regulated in MKN45 cells, migration and HGF levels decreased. Together, these results demonstrate that HGF/c-met can activate PI3K/Akt and downstream NF-κB signaling to promote HPA expression and subsequent tumor metastasis.

miR-149 represses metastasis of hepatocellular carcinoma by targeting actin-regulatory proteins PPM1F

microRNAs have been implicated in hepatocellular carcinoma (HCC) metastasis, which is predominant cause of high mortality in these patients. Although an increasing body of evidence indicates that miR-149 plays an important role in the growth and metastasis of multiple types of cancers, its role in the progression of HCC remains unknown. Here, we demonstrated that miR-149 was significantly down-regulated in HCC, which was correlated with distant metastasis and TNM stage with statistical significance. A survival analysis showed that decreased miR-149 expression was correlated with a poor prognosis of HCC as well. We found that over-expression of miR-149 suppressed migration and invasion of HCC cells in vitro. In addition, we identified PPM1F (protein phosphatase, Mg2+/Mn2+-dependent, 1F) as a direct target of miR-149 whose expression was negatively correlated with the expression of miR-149 in HCC tissues. The re-expression of PPM1F rescued the miR-149-mediated inhibition of cell migration and invasion. miR-149 regulated formation of stress fibers to inhibit migration, and re-expression of PPM1F reverted the miR-149-mediated loss of stress fibers. Moreover, we demonstrated that over-expression of miR-149 reduced pMLC2, a downstream effector of PPM1F, in MHCC-97H cells. In vivo studies confirm inhibition of HCC metastasis by miR-149. Taken together, our findings indicates that miR-149 is a potential prognostic biomarker of HCC and that the miR-149/PPM1F regulatory axis represents a novel therapeutic target for HCC treatment.

Multiple Antigenic Peptides of Human Heparanase Elicit a Much More Potent Immune Response against Tumors

Peptide vaccination for cancer immunotherapy requires an ideal immune response induced by epitope peptides derived from tumor-associated antigens (TAA). Heparanase is broadly expressed in various advanced tumors. Accumulating evidence suggests that heparanase can serve as a universal TAA for tumor immunotherapy. However, due to the low immunogenicity of peptide vaccines, an ideal immune response against tumors usually cannot be elicited in patients. To increase the immunogenicity of peptide vaccines, we designed three 4-branched multiple antigenic peptides (MAP) on the basis of the human leukocyte antigen (HLA)-A2–restricted cytotoxic T lymphocyte (CTL) epitopes of human heparanase that we identified previously as antigen carriers. Our results show that MAP vaccines based on the HLA-A2–restricted CLT epitopes of human heparanase were capable of inducing HLA-A2–restricted and heparanase-specific CTL in vitro and in mice. Moreover, compared with their corresponding linear peptides, heparanase MAP vaccines elicited much stronger lysis of tumor cells by activating CD8+ T lymphocytes and increasing the releasing of IFN-γ. However, these heparanase-specific CTLs did not lyse heparanase-expressing autologous lymphocytes and dendritic cells, which confirm the safety of these MAP vaccines. Therefore, our findings indicate that MAP vaccines based on CTL epitopes of human heparanase can be used as potent immunogens for tumor immunotherapy because of advantages such as broad spectrum, high effectiveness, high specificity, and safety. Cancer Prev Res; 4(8); 1285–95. ©2011 AACR.

Noninvasive and real-time monitoring of the therapeutic response of tumors in vivo with an optimized hTERT promoter

Telomerase is commonly recognized as an effective anticancer target. The human telomerase reverse transcriptase (hTERT), the rate‐limiting component of telomerase, is expressed in most malignant tumors, but it is not found in most normal somatic cells. Here, we report a real‐time and noninvasive method to monitor tumor response to a lentivirus‐based hTERT‐conditional suicidal gene therapy.

An hTERT/ZEB1 complex directly regulates E-cadherin to promote epithelial-to-mesenchymal transition (EMT) in colorectal cancer.

In human cancer, high telomerase expression is correlated with tumor aggressiveness and metastatic potential. Telomerase activation occurs through telomerase reverse transcriptase (hTERT) induction, which contributes to malignant transformation by stabilizing telomeres. Previous studies have shown that hTERT can promote tumor invasion and metastasis of gastric cancer, liver cancer and esophageal cancer. Epithelial-to-mesenchymal transition (EMT), a requirement for tumor invasion and metastasis, plays a key role in cancer progression. Although hTERT promotes EMT through Wnt signaling in several cancers, it is unknown if other signaling pathways are involved. In the present study, we found that hTERT and ZEB1 form a complex, which directly binds to the E-cadherin promoter, and then inhibits E-cadherin expression and promots EMT in colorectal cancer cells. hTERT overexpression in HCT116 and SW480 cells could induce E-cadherin down-regulation. However, E-cadherin expression was recovered when ZEB1 function was impaired even during hTERT overexpression. Taken together, our findings suggest that hTERT can promote cancer metastasis by stimulating EMT through the ZEB1 pathway and therefore inhibiting them may prevent cancer progression.

SDF-1/CXCR4 Axis Promotes MSCs to Repair Liver Injury Partially through Trans-Differentiation and Fusion with Hepatocytes

MSCs have become a popular target for developing end-stage liver therapies. In this study, two models of bone marrow chimeric mice were used to construct the liver failure models. Then it was found that MSCs can transdifferentiate into hepatocyte-like cells and these hepatocyte-like cells can significantly express albumin. Furthermore it was also found that MSCs can fuse with the hepatocytes and these cells had the proliferation activity. However, the percentage of transdifferentiation was significantly higher than fusion. So it was considered that MSCs which transdifferentiated into hepatocyte-likes cells played important roles for repairing the injuring liver function.

hTERT mediates gastric cancer metastasis partially through the indirect targeting of ITGB1 by microRNA-29a.

Human telomerase reverse transcriptase (hTERT) plays a key role in tumor invasion and metastasis, but the mechanism of its involvement in these processes is not clear. The purpose of this study is to investigate the possible molecular mechanism of hTERT in the promotion of gastric cancer (GC) metastasis. We found that the up-regulation of hTERT in gastric cancer cells could inhibit the expression of miR-29a and enhance the expression of Integrin β1 (ITGB1). In addition, the invasive capacity of gastric cancer cells was also highly increased after hTERT overexpression. Our study also found that the restoration of miR-29a suppressed the expression of ITGB1 and inhibited GC cell metastasis both in vitro and in vivo. Taken together, our results suggested that hTERT may promote GC metastasis through the hTERT-miR-29a-ITGB1 regulatory pathway.

Antitumor effect of new multiple antigen peptide based on HLA‐A0201‐restricted CTL epitopes of human telomerase reverse transcriptase (hTERT)

The development of peptide vaccines aimed at enhancing immune responses against tumor cells is becoming a promising area of research. Human telomerase reverse transcriptase (hTERT) is an ideal universal target for novel immunotherapies against cancers. The aim of this work was to verify whether the multiple antigen peptides (MAP) based on HLA‐A0201‐restricted CTL epitopes of hTERT could trigger a better and more sustained CTL response and kill multiple types of hTERT‐positive tumor cells in vitro and ex vivo. Dendritic cells (DC) pulsed with MAP based on HLA‐A0201‐restricted CTL epitopes of hTERT (hTERT‐540, hTERT‐865 and hTERT‐572Y) were used to evaluate immune responses against various tumors and were compared to the immune responses resulting from the use of corresponding linear epitopes and a recombinant adenovirus‐hTERT vector. A 4‐h standard 51Cr‐release assay and an ELISPOT assay were used for both in vitro and ex vivo analyses. Results demonstrated that targeting hTERT with an adenovector was the most effective way to stimulate a CD8+ T cell response. When compared with linear hTERT epitopes, MAP could trigger stronger hTERT‐specific CTL responses against tumor cells expressing hTERT and HLA‐A0201. In contrast, the activated CTL could neither kill the hTERT‐negative tumor cells, such as U2OS cells, nor kill HLA‐A0201 negative cells, such as HepG2 cells. We also found that these peptide‐specific CTL could not kill autologous lymphocytes and DC with low telomerase activity. Our results indicate that MAP from hTERT can be exploited for cancer immunotherapy.

An Optimized Telomerase-Specific Lentivirus for Optical Imaging of Tumors

Advances in medical imaging techniques, such as ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography, have made great progress in detecting tumors. However, these imaging techniques are unable to differentiate malignant tumors from benign ones. Recently developed optical imaging of tumors in small animals provides a useful method to distinguish malignant tumors from their surrounding normal tissues. Human telomerase reverse transcriptase (hTERT) is normally inactivated in most somatic cells, whereas it is commonly reactivated in many cancer cells. In this study, we constructed a lentiviral vector that expresses green fluorescent protein (GFP) driven by an optimized hTERT promoter to create a noninvasive tumor-specific imaging methodology. The activity of this optimized hTERT promoter was found to be equal to the activity of SV40 and cytomegalovirus promoters. In vitro experiments showed that GFP was only expressed in telomerase-positive tumor cells infected with this lentivirus, whereas there was no GFP expression in telomerase-negative tumor cells or normal somatic cells. We also found that subcutaneous telomerase-positive tumors could be visualized 24 hours after an intratumoral injection with this lentivirus by using a charge-coupled device (CCD) camera. In contrast, telomerase-negative tumors could not be imaged after an intratumoral injection even for 30 days. These results suggest that infection with lentivirus containing this optimized hTERT promoter might be a useful diagnostic tool for the real-time visualization of macroscopically invisible tumor tissues using a highly sensitive CCD imaging system.