Gli-1 siRNA induced apoptosis in Huh7 cells

Essential role of Card11 in airway hyperresponsiveness in high-fat diet-induced obese mice

A high-fat diet (HFD) can induce airway hyperresponsiveness (AHR) in obese mice, independent of allergic sensitization. This study aimed to identify the key molecules related to AHR in HFD-induced obese mice. In a cluster analysis of time series gene expression in the adipose and lung tissues of HFD-induced obese mice, we identified the Caspase Recruitment Domain Family Member 11 (Card11) gene as an essential molecule. We measured CARD11 expression in peripheral blood mononuclear cells (PBMCs) from obese individuals with asthma and performed Card11 signal inhibition in HFD-induced obese mice via Card11 siRNA. Card11 expression was significantly increased in M1 macrophages (IL-1β+CD11c+CD206- in CD11b+) in adipose tissue and in ILC3s (RORγt+ in IL7R+ of Lin-) in lung tissue from HFD-induced obese mice. In addition, CARD11+ populations among ILC3s and LPS-stimulated IL-1β+CD16+ monocytes from the PBMCs of obese individuals with asthma were significantly greater than those from obese controls or nonobese individuals with asthma. AHR in HFD-induced obese mice disappeared when we inhibited the Card11 signaling pathway by administering Card11 siRNA during the first or last seven weeks of the 13-week HFD feeding. Finally, we confirmed that Card11 siRNA decreased the number of M1 macrophages in adipose tissue and the number of ILC3s in lung tissue in vitro. Card11 significantly contributes to the development of AHR in HFD-induced obese mice by affecting immune cells in both adipose and lung tissues. The middle stage of HFD feeding seemed to be critical for these processes.

Natural cordycepin induces apoptosis and suppresses metastasis in breast cancer cells by inhibiting the Hedgehog pathway

In the study, we investigated the role of the hedgehog (Hh) pathway in cordycepin's effects on human breast cancer cells, with respect to cell growth, apoptosis and metastasis. We found cordycepin to have low toxicity but significant anticancer effects. Cordycepin-induced apoptosis led to increased PUMA, CYTO-C, FAS, DR4/5, and cleaved caspase-3; and decreased BCL-2, XIAP and PDGFR-α. Cordycepin inhibited metastasis, which was associated with up-regulated E-cadherin, and down-regulated N-cadherin, SNAIL, SLUG and ZEB1. Cordycepin also inhibited expression of Hh pathway components and GLI transcriptional activity. Inversely, knockout of GLI blocked cordycepin-mediated effects on the apoptotic, epithelial-mesenchymal transition (EMT) and Notch pathways, which indicates that GLI is crucial for cordycepin's effects against breast cancer. Inhibition of GLI enhanced cordycepin's effect on breast cancer cell growth. To our knowledge, this is the first study of cordycepin's effect on the Hh pathway in breast cancer, and provides preliminary data for the in vivo study, and possible therapeutic use, of cordycepin.

Mismatch repair deficiency and aberrations in the Notch and Hedgehog pathways are of prognostic value in patients with endometrial cancer

The aim of this study was to investigate the prognostic value of the Hedgehog (Gli, Patched-1, Shh, Smo) and Notch (Jag1, Notch2, Notch3) pathway members, in comparison to a panel of proteins (ER, PgR, HER2/neu, Ki67, p53, p16, PTEN and MMR) previously suggested to be involved in the pathogenesis of endometrial cancer, in association with clinical outcome and standard clinicopathological characteristics. A total of 204 patients with histological diagnosis of endometrial cancer treated from 2004 to 2013 were included. The evaluation of protein expression was assessed by immunohistochemistry. Univariate analysis showed that higher Ki67 labeling, expression of PTEN, p16, Notch2 and Notch3 proteins, as well as MMR proficiency were associated with increased relapse and mortality rate. Additionally, Patched-1 protein expression was associated with worse DFS, while p53 overexpression was associated with worse OS. In multivariate analyses, patients with MMR proficient tumors had more than double risk for death than patients with MMR deficient (MMRd) tumors (adjusted HR = 2.19, 95% CI 1.05–4.58, p = 0.036). Jag1 positivity conferred reduced mortality risk (HR = 0.48, 95% CI 0.23–0.97, p = 0.042). However, as shown by hierarchical clustering, patients fared better when their tumors expressed high Jag1 protein in the absence of Notch2 and Notch3, while they fared worse when all three proteins were highly expressed. Patched-1 positivity conferred higher risk for relapse (HR = 2.04, 95% CI 1.05–3.96, p = 0.036).

Aberrant expression of key components of the Notch and Hedgehog signaling pathways, as well as MMRd may serve as independent prognostic factors for recurrence and survival in patients with endometrial cancer.

Glaucocalyxin A exerts anticancer effect on osteosarcoma by inhibiting GLI1 nuclear translocation via regulating PI3K/Akt pathway

Osteosarcoma, the most common malignant bone tumor with recurring disease or lung metastases, has become one of the leading causes of death in humans. In the current study, we made an investigation on the anticancer effect of glaucocalyxin A, a bioactive ent-kauranoid diterpenoid isolated from Rabdosia japonica var., and unraveled the underlying mechanisms. Here, we found that Glaucocalyxin A inhibited the cell viability of numerous osteosarcoma cells. Our results showed that Glaucocalyxin A exerted the pro-apoptotic effect on human osteosarcoma cells, MG-63 and HOS cells. Glaucocalyxin A induced apoptosis by mitochondrial apoptotic pathway through several steps including increasing the Bax/Bcl-2 ratio, triggering the intracellular reactive oxygen species (ROS) generation, reducing mitochondrial membrane potential (MMP), and inducing cleavage of caspase-9 and caspase-3. We demonstrated that Glaucocalyxin A induced apoptosis via inhibiting Five-zinc finger Glis 1 (GLI1) activation by overexpression and knockdown of GLI1 in vitro. We also found that Glaucocalyxin A inhibited GLI1 activation via regulating phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) signaling pathway. We further confirmed our findings by using PI3K activator and inhibitor to verify the inhibitory effect of Glaucocalyxin A on PI3K/Akt/GLI1 pathway. Moreover, our in vivo study revealed that glaucocalyxin A possessed a remarkable antitumor effect with no toxicity in the xenograft model inoculated with HOS tumor through the same mechanisms as in vitro. In conclusion, our results suggested that Glaucocalyxin A induced apoptosis in osteosarcoma by inhibiting nuclear translocation of GLI1 via regulating PI3K/Akt signaling pathway. Thus, Glaucocalyxin A might be a potential candidate for human osteosarcoma in the future.

Sonic hedgehog signaling pathway mediates development of hepatocellular carcinoma

Although abnormal activation of the sonic hedgehog (Shh) signaling pathway has been demonstrated in human hepatocellular carcinoma (HCC) patients and in most HCC cell lines, the mechanism by which the Shh pathway promotes the development of HCC remains uncertain. Using a liver cancer model induced by diethylnitrosamine (DEN) which mimics the process from liver injury, abnormal hepatocyte proliferation, and hepatocirrhosis to hepatocyte canceration, we investigated the abnormal activation of the Shh pathway by examining the expression of Shh, patched-1 (Ptch), smoothened (SMO), and glioma-associated oncogene-1 (Gli1) genes. During this process, the expression of CDK1 and cyclin B1 protein, which are two components of the M-phase promoting factor (MPF) controlling G2/M transition, was also examined to explore the potential relationship between Shh activation and cell cycle progression. We observed that the cells with Shh, Ptch, and Gli1 protein expression were mainly distributed in hyperplastic nodule, cancerous node, the epithelia of interlobular bile duct, and precancerous tissues. A gradually increasing tendency of the positive expression rate of Shh, Ptch, and Gli1 proteins in the process from the beginning normal tissue to the final cancer formation was revealed. The cyclin B1 and CDK1 expression level was higher in the DEN-induced rats as compared with normal rats, and their expression was mainly distributed in the portal area of the liver, hyperplastic nodule, cancerous node, and precancerous tissues. Our results suggested that the Shh signaling pathway is activated during liver carcinogenesis, and activated Shh signaling promotes the cell proliferation by facilitating the G2/M transition through increasing the expression of cyclin B1 and CDK1 protein, which eventually results in the development of liver cancer. Better understanding of the Shh signaling pathway in HCC may contribute to the development of novel therapeutic strategies in inhibiting cell proliferation and promoting cell cycle arrest.

FOXR2 contributes to cell proliferation and malignancy in human hepatocellular carcinoma

Forkhead box R2 (FOXR2), a member of forkhead box (FOX) family, has been identified as an oncogene in medulloblastoma and breast cancer recently. However, the expression and function of FOXR2 in hepatocellular carcinoma cell (HCC) are still unclear. Here, we report that FOXR2 is frequently upregulated in 25/42 (59.5 %) of HCC specimens compared with neighboring non-cancerous tissues in messenger RNA (mRNA) level and further confirmed by immunohistochemistry analysis in protein level. Cellular function analyses revealed that FOXR2 promoted cell growth and colony formation, whereas knockdown of FOXR2 by RNA inference inhibited cell growth and decreased the growth ability of HCC cells in soft agar. Moreover, we also found FOXR2 overexpression facilitated the development of tumor xenografts in nude mice model. In addition, we validated β-catenin, Skp2, c-Myc, and Gli-1 as the potential downstream effectors of FOXR2 in the regulation of cell proliferation and malignancy by quantitative real-time PCR analysis. Collectively, our data suggest that FOXR2 promotes cell proliferation and malignancy in HCC and could be a novel promising therapeutic target for this disease.

Mitochondria-derived reactive oxygen species drive GANT61-induced mesothelioma cell apoptosis

Gli transcription factors of the Hedgehog (Hh) pathway have been reported to be drivers of malignant mesothelioma (MMe) cell survival. The Gli inhibitor GANT61 induces apoptosis in various cancer cell models, and has been associated directly with Gli inhibition. However various chemotherapeutics can induce cell death through generation of reactive oxygen species (ROS) but whether ROS mediates GANT61-induced apoptosis is unknown. In this study human MMe cells were treated with GANT61 and the mechanisms regulating cell death investigated. Exposure of MMe cells to GANT61 led to G1 phase arrest and apoptosis, which involved ROS but not its purported targets, GLI1 or GLI2. GANT61 triggered ROS generation and quenching of ROS protected MMe cells from GANT61-induced apoptosis. Furthermore, we demonstrated that mitochondria are important in mediating GANT61 effects: (1) ROS production and apoptosis were blocked by mitochondrial inhibitor rotenone; (2) GANT61 promoted superoxide formation in mitochondria; and (3) mitochondrial DNA-deficient LO68 cells failed to induce superoxide, and were more resistant to apoptosis induced by GANT61 than wild-type cells. Our data demonstrate for the first time that GANT61 induces apoptosis by promoting mitochondrial superoxide generation independent of Gli inhibition, and highlights the therapeutic potential of mitochondrial ROS-mediated anticancer drugs in MMe.

Heterogeneity of hepatocellular carcinoma contributes to cancer progression

Hepatocellular carcinoma (HCC) is a highly heterogeneous disease displaying differences in angiogenesis, extracellular matrix proteins, the immune microenvironment and tumor cell populations. Additionally, genetic variations and epigenetic changes of HCC cells could lead to aberrant signaling pathways, induce cancer stem cells and enhance tumor progression. Thus, the heterogeneity in HCC contributes to disease progression and a better understanding of its heterogeneity will greatly aid in the development of strategies for the HCC treatment.

P162 enhances radiosensitivity of esophageal carcinoma Eca109 cells by inhibiting Hedgehog signaling transcription factor Gli-1

AIM: To investigate whether P162 enhances radiosensitivity of esophageal carcinoma cell line Eca109 by inhibiting Hedgehog signaling transcription factor Gli-1.

METHODS: Eca109 cells (a total dose of 60 Gy) to induce radioresistant esophageal carcinoma cell line Eca109R. The inhibition of cell proliferation was determined by Cell Counting Kit assay. The expression of Gli-1 was detected by immunohistochemistry and immunofluorescence. HE staining was employed to observe the changes in cell morphology. Western blot was employed to determine the nuclear expression of Gli-1 and dynamic changes of Gli-1 in irradiated Eca109 cells. Apoptosis was determined by flow cytometry. The following four groups were included in the experiments: untreated cells, P162-treated cells, irradiated cells, and P162-treated irradiated cells. Eca109 and Eca109R cells were included in each group.

RESULTS: Eca109R possessing certain radiation resistance displayed lower ability of growth inhibition than Eca109 cells. Nuclear Gli-1 expression was significantly higher in Eca109R cells than in Eca109 cells (0.45 ± 0.01 vs 0.32 ± 0.01, P < 0.0001). On days 2 and 14 after irradiation, the nuclear expression of Gli-1 in Eca109 cells was higher than that in control cells (0.0882 ± 0.011, 0.3560 ± 0.015 vs 0.2552 ± 0.0103, P < 0.05). In both Eca109R and Eca109 cells, the nuclear expression of Gli-1 was reduced after treatment with 20 µmol/L P162 [0.2553 ± 0.011, 0.2578 ± 0.014 (non-irradiation); 0.1324 ± 0.012, 0.0595 ± 0.011(2 d after irradiation); 0.1741 ± 0.013, 0.2397 ± 0.112 (14 d after irradiation), P < 0.0001]. P162 combined with radiotherapy facilitated cells apoptosis.

CONCLUSION: Nuclear Gli-1 expression is related to radioresistance of esophageal cancer cells. P162 enhances radiosensitivity of Eca109 cell possibly by inhibiting Gli-1 expression and promoting apoptosis.

Treatment of etoposide combined with 15-deoxy-Δ12,14-prostaglandin J2 exerted synergistic antitumor effects against renal cell carcinoma via peroxisome proliferator-activated receptor-γ-independent pathways

Renal cell carcinoma (RCC) is characterized by diverse clinical manifestations, few early warning signs and a resistance to radiotherapy and chemotherapy. Although several clinical trials have investigated potential effective therapeutic strategies for RCC, the chemoresistance of RCC has not yet been overcome. An endogenous ligand for the peroxisome proliferator-activated receptor-γ (PPARγ), 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂), was shown to induce apoptosis in RCC. The aim of the present study was to investigate the synergistic effects of carcinostatics on the antitumor activity of 15d-PGJ₂ in the Caki-2 human RCC cell line with the MTT assay. Our results demonstrated that the topoisomerase-II inhibitor etoposide (VP-16) exhibited cytotoxic effects synergistically with 15d-PGJ₂. Furthermore, the presence of the PPARγ antagonist GW9662 did not protect Caki-2 cells against 15d-PGJ₂-induced cytotoxicity. Additionally, it was observed that the combined treatment of VP-16 and 15d-PGJ₂ activated caspase-3 more efficiently compared to each treatment alone. Therefore, the combined treatment with 15d-PGJ₂ and VP-16 exhibited synergistic antitumor activity independently of PPARγ.

Hedgehog signaling inhibitor cyclopamine induces apoptosis by decreasing Gli2 and Bcl2 expression in human salivary pleomorphic adenoma cells

Pleomorphic adenoma is the most common benign neoplasm of the salivary gland. Few studies are currently available on pleomorphic adenoma cell apoptosis. The aim of this study was to investigate the effect of cyclopamine induction apoptosis in human salivary pleomorphic adenoma (HSPA) cells and the impact on Gli2 and Bcl2 mRNA levels. Cells were quantified and cell morphology was visualized under microscope. Flow cytometry was used to detect the apoptotic rate. Cyclopamine is considered an efficient blocker of the hedgehog (Hh) signaling pathway. Following treatment with 10 μmol/l cyclopamine for 48 h, the number of cells were reduced, and nuclear pycnosis or fragmentation, as well as chromatospherite disfiguration apoptotic morphology were observed under microscope. One-way ANOVA test results revealed a significantly greater decrease (P<0.01) of Gli2 and Bcl2 mRNA levels in the cyclopamine-treated group as compared to the blank control group and dimethyl sulfoxide (DMSO)-treated group. Following treatment with 10 μmol/l cyclopamine for 24 h, the apoptotic rate of the cyclopamine-treated group was significantly higher than that of the blank control and DMSO-treated group (P<0.01). Findings of this study showed that cyclopamine affected the mechanism of HSPA cell apoptosis, which may be associated with the downregulation of Gli2 and Bcl2 mRNA expression levels and the activation of the mitochondrial apoptotic pathways.

Diindolylmethane-mediated Gli1 protein suppression induces anoikis in ovarian cancer cells in vitro and blocks tumor formation ability in vivo

Anoikis is a cell death that occurs due to detachment of a cell from the extracellular matrix (ECM). Resistance to anoikis is a primary feature of a cell that undergoes metastasis. In this study for the first time, we demonstrated the potential role of Gli1 in anoikis resistance. Treatment of various ovarian cancer cells by different concentrations of diindolylmethane (DIM), an active ingredient of cruciferous vegetables, reduced the anoikis resistance in a concentration-dependent manner. Reduction in anoikis resistance was associated with a decrease in the expression of Gli1 and an increase in the cleavage of poly(ADP-ribose) polymerase (PARP). Sonic hedgehog (Shh) treatment not only increased the expression of Gli1, but also blocked anoikis induced by DIM and abrogated the change in the expression of Gli1 and cleaved PARP by DIM. To confirm the role of Gli1, hedgehog inhibitor cyclopamine, Gli1 siRNA and Gli1(-/-) mouse embryonic fibroblasts (MEFs) were used. Cyclopamine treatment alone significantly reduced anoikis resistance in A2780 and OVCAR-429 cells. Cyclopamine-mediated reduction in anoikis resistance was associated with reduced expression of Gli1 and induction of cleaved PARP. Shh treatment blocked cyclopamine-induced anoikis. Silencing Gli1 expression induced anoikis and cleavage of PARP in A2780 and OVCAR-429 cells. Furthermore, Gli1(-/-) MEFs were more sensitive to anoikis compared with Gli1(+/+) MEFs. Our in vivo studies established that DIM- or cyclopamine-treated ovarian cancer cells under suspension culture conditions drastically lost their ability of tumor formation in vivo in mice. Taken together, our results establish that Gli1 is a critical player in anoikis resistance in ovarian cancer.

Gli inhibitor GANT61 causes apoptosis in myeloid leukemia cells and acts in synergy with rapamycin

Aberrant reactivation of Gli signaling has been described in a wide variety of human cancers and rapamycin can down-regulate Gli pathway in some solid tumors. In this study, we attempt to define the cytotoxic effect of Gli inhibitor on AML cells. And the regulation action of rapamycin on Gli in AML cells also has been assessed. Gli inhibitor GANT61 caused growth arrest and apoptosis in AML cells. Rapamycin decreased not only the Gli protein and mRNA expressions but also expression of the Gli-luciferase reporter in AML cells. Synergism effect between GANT61 and rapamycin was found in Kasumi-1, HL-60 and U937 cell lines. The results suggest that aberrant Gli activation is a feature of some myeloid leukemic cells and Gli activiation can be down-regulated by rapamycin.

Polymeric nanoparticle-encapsulated hedgehog pathway inhibitor HPI-1 (NanoHHI) inhibits systemic metastases in an orthotopic model of human hepatocellular carcinoma

PURPOSE

To illustrate the prognostic significance of hedgehog (Hh) signaling in patients with hepatocellular carcinoma (HCC) and to evaluate the efficacy of a novel nanoparticle-encapsulated inhibitor of the Hh transcription factor, Gli1 (NanoHHI) using in vitro and in vivo models of human HCCs.

EXPERIMENTAL DESIGN

Patched1 (Ptch1) expression was detected in tumor tissue microarrays of 396 patients with HCC who underwent curative surgical resection during February 2000 to December 2002. Prognostic significance was assessed using Kaplan-Meier survival estimates and log-rank tests. The effects of NanoHHI alone and in combination with sorafenib were investigated on HCC cell lines. Primary HCC tumor growth and metastasis were examined in vivo using subcutaneous and orthotopic HCC xenografts in nude mice.

RESULTS

Elevated expression of Ptch1 in HCC tissues was significantly related to disease recurrence, as well as a shorter time to recurrence in patients with HCC. In vitro, NanoHHI significantly inhibited the proliferation and invasion of HCC cell lines. NanoHHI potently suppressed in vivo tumor growth of HCC xenografts in both subcutaneous and orthotopic milieus, and in contrast to sorafenib, resulted in significant attenuation of systemic metastases in the orthotopic setting. Furthermore, NanoHHI significantly decreased the population of CD133-expressing HCC cells, which have been implicated in tumor initiation and metastases.

CONCLUSION

Downstream Hh signaling has prognostic significance in patients with HCC as it predicts early recurrence. Gli inhibition through NanoHHI has profound tumor growth inhibition and antimetastatic effects in HCC models, which may provide a new strategy in the treatment of patients with HCC and prevention post-operative recurrence.

shRNA-mediated silencing of Gli2 gene inhibits proliferation and sensitizes human hepatocellular carcinoma cells towards TRAIL-induced apoptosis

Aberrant activation of the Hedgehog (Hh) signaling pathway has been reported in various cancer types including hepatocellular carcinoma (HCC). As a key effector of this signaling, Gli2 plays a crucial role in carcinogenesis, including the activation of genes encoding apoptosis inhibitors and cell-cycle regulators. In this study, we examined the role of Gli2 proliferation and survival of HCC cells. First, the expression levels of Hh pathway components were detected in a subset of HCC cell lines. To establish the role of Gli2 in maintaining the tumorigenic properties of HCC cells, we developed small hairpin RNA (shRNA) targeting Gli2 and transfected it into SMMC-7721 cell, which was selected with high level of Hh signaling expression. Next, effects of Gli2 gene silencing, on cell proliferation and on the expression of cell cycle-related proteins were evaluated, then, whether down-regulation of Gli2 renders HCC cell susceptible to TRAIL was examined in vitro. Knockdown of Gli2 inhibited cell proliferation and induced G1 phase arrest of cell cycle in SMMC-7721 cell through down-regulation of cyclin D1, cyclinE2, and up-regulation of p21-WAF1. Also, Gli2 gene siliencing sensitized SMMC-7721 cell to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by reducing the expression of the long and short isoform of c-FLIP and Bcl-2, and then augmented the activation of initiator caspases-8/-9 and effector caspases-3, which induces PARP cleavage. In conclusion, our data suggest that Gli2 plays a predominant role in the proliferation and apoptosis resistance of HCC cells, and that knockdown of Gli2 may be a novel anticancer strategy for the treatment of HCC.

GLI2 is a potential therapeutic target in pediatric medulloblastoma

To determine whether the zinc finger transcription factors GLI1 to GLI3 and suppressor of fused (SUFU) components of the Sonic hedgehog signaling pathway may be prognostic markers and potential therapeutic targets in pediatric medulloblastoma (MB), we investigated the relationship of the expression of these proteins to prognosis in the MB of 124 patients who had undergone surgery at the Hospital for Sick Children (Toronto, Ontario, Canada). The expressions of GLI1 (p = 0.011) and GLI2 (p = 0.003), but not of GLI3 (p = 0.774) or SUFU (p = 0.137), in the MB were associated with a worse overall survival by Kaplan-Meier analysis. Overall survival of patients positive for GLI1 and GLI2 was 6.01 ± 0.85 years and 5.27 ± 1.44 years, respectively, versus 10.11 ± 1.52 years and 10.18 ± 0.22 years for patients negative for GLI1 and GLI2, respectively. Knockdown of GLI2 in 3 MB cell lines resulted in decreased cell number and viability, as determined by the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay; knockdown of GLI1 had no effect. The decrease in cell number with GLI2 knockdown was caused by G0 cell cycle arrest; there was no induction of apoptosis. These results suggest that targeting the Sonic hedgehog pathway in positive patients may be a useful adjuvant therapeutic strategy for MB.

15-Deoxy-Δ12,14-prostaglandin J2 enhanced the anti-tumor activity of camptothecin against renal cell carcinoma independently of topoisomerase-II and PPARγ pathways

Renal cell carcinoma (RCC) is chemoresistant cancer. Although several clinical trials were conducted to explore effective medications, the chemoresistance of RCC has not yet been conquered. An endogenous ligand for peroxisome proliferator-activated receptor-γ (PPARγ), 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)), induces apoptosis in RCC. Here, we examined synergistic effects of several carcinostatics on the anti-tumor activity of 15d-PGJ(2) in Caki-2 cell line by MTT assay. A topoisomerase-I inhibitor, camptothecin (CPT), exhibited synergistically toxicity with 15d-PGJ(2), but neither 5-fluorouracil nor cisplatin did. The combination of 15d-PGJ(2) and a topoisomerase-II inhibitor, doxorubicine, did not cause synergistic cell growth inhibition. The synergistic effect of topoisomerase-I and II inhibitors was not also detected. A PPARγ antagonist, GW9662, did not prevent Caki-2 from undergoing 15d-PGJ(2)-induced cytotoxicity. The treatment of CPT combined with 15d-PGJ(2) activated caspase-3 more than the separate treatment. These results suggest that 15d-PGJ(2) exhibited the anti-tumor activity synergistically with CPT independent of topoisomerase-II and PPARγ.

A novel microRNA mmu-miR-466h affects apoptosis regulation in mammalian cells

This study determined the changes in microRNA (miRs) expression in mammalian Chinese hamster ovary (CHO) cells undergoing apoptosis induced by exposing the cells to nutrient-depleted media. The apoptosis onset was confirmed by reduced cell viability and Caspase-3/7 activation. Microarray comparison of known mouse and rat miRs in CHO cells exposed to fresh or depleted media revealed up-regulation of the mouse miR-297-669 cluster in CHO cells subjected to depleted media. The mmu-miR-466h was chosen for further analysis as the member of this cluster with the highest overexpression and its up-regulation in depleted media was confirmed with qRT-PCR. Since miRs suppress mRNA translation, we hypothesized that up-regulated mmu-miR-466h inhibits anti-apoptotic genes and induces apoptosis. A combination of bioinformatics and experimental tools was used to predict and verify mmu-miR-466h anti-apoptotic targets. 8708 predicted targets were obtained from miRecords database and narrowed to 38 anti-apoptotic genes with DAVID NCBI annotation tool. Several genes were selected from this anti-apoptotic subset based on nucleotide pairing complimentarity between the mmu-miR-466h seed region and 3' UTR of the target mRNAs. The qRT-PCR analysis revealed reduced mRNA levels of bcl2l2, dad1, birc6, stat5a, and smo genes in CHO cells exposed to depleted media. The inhibition of the mmu-miR-466h increased the expression levels of those genes and resulted in increased cell viability and decreased Caspase-3/7 activation. The up-regulation of mmu-miR-466h in response to nutrients depletion causes the inhibition of several anti-apoptotic genes in unison. This suggests the pro-apoptotic role of mmu-miR-466h and its capability to modulate the apoptotic pathway in mammalian cells.

NKX3.1 potentiates TNF-alpha/CHX-induced apoptosis of prostate cancer cells through increasing caspase-3 expression and its activity

NKX3.1, a prostate-specific homeobox gene, plays an important role in prostate cancer and usually functions as tumor suppressor gene. Previously we have demonstrated that forced expression of NKX3.1 reduced cell growth and invasion in prostate cancer cell line PC-3. Presently, we investigated the effect of NKX3.1 on the sensitivity of the prostate cancer cells to apoptosis inducer tumor necrosis factor-alpha (TNF-alpha) and cycloheximide (CHX). PC-3 cells were transfected with NKX3.1 expression plasmid (pcDNA3.1-NKX3.1) and LNCaP cells were transfected with siRNA expression plasmid (pRNAT-RNAi1) targeting NKX3.1. The cell morphology and apoptotic rate were analyzed by Hoechst 33342 staining and Flow Cytometry in absence or presence of TNF-alpha and CHX. The activity of caspase-3 was determined using DEVD-pNA as substrate. Simultaneously, the effect of NKX3.1 on caspase-3 expression was detected using RT-PCR and Western blot. The results showed that ectopic expression of NKX3.1 promoted TNF-alpha/CHX-induced apoptosis in PC-3 cells, whereas knockdown of NKX3.1 protected LNCaP cells from apoptosis induced by TNF-alpha/CHX. The pro-apoptosis activity of NKX3.1 might partially contribute to its elevation of caspase-3 expression and activity. Manipulating NKX3.1 expression should be a promising therapeutic strategy for treating both androgen-dependent and androgen-independent prostate cancer.

Curcumin suppresses PPARδ expression and related genes in HT-29 cells

AIM: To investigate the effects of curcumin on the expression of peroxisome proliferator-activated receptorδ (PPARδ) and related genes in HT-29 cells.

METHODS: HT-29 cells were treated with curcumin (0-80 &mgr;mol/L) for 24 h. The effects of curcumin on the morphology of HT-29 cells were studied by Hoechst 33342 staining. The activity of caspase-3 was determined using DEVD-pNA as substrate. The levels of peroxisome PPARδ, 14-3-3epsilon and vascular endothelial growth factor (VEGF) in HT-29 cells were determined by Western blotting analysis and their mRNA expression was determined by real-time quantitative RT-PCR.

RESULTS: Treatment with 10-80 &mgr;mol/L curcumin induced typical features of apoptosis and activated the caspase-3 in HT-29 cells. The expression of PPARδ, 14-3-3epsilon and VEGF was reduced and the activity of β-catenin/Tcf-4 signaling was inhibited by curcumin treatment.

CONCLUSION: Curcumin can induce apoptosis of HT-29 cells and down-regulate the expression of PPARδ, 14-3-3epsilon and VEGF in HT-29.

Expression patterns and polymorphisms of PTCH in Chinese hepatocellular carcinoma patients

Aberrant activation of Hedgehog signaling pathway leads to pathological consequences in a variety of human tumors. PTCH (PTCH1), the receptor of Hedgehog pathway, is reported to function as a gatekeeper in tumor formation. Here we report, by semi-quantitative RT-PCR, PTCH expression was found in 38 hepatocellular carcinoma (HCC) patients (66%). Evidences from real time quantitative RT-PCR further indicate that compared to their matched nontumorous liver tissue, PTCH exhibit a higher expression in well and moderate differentiated tumor, but a lower expression in poorly differentiated tumor. Immunohistochemical staining showed PTCH protein was detected in the cytoplasm of 56.3% HCC samples (9/16). For the first time, we investigate the polymorphisms of PTCH in HCC. First we sequenced the recognized mutation hot spots regions of PTCH of 38 HCC samples. Two previously reported single nucleotide polymorphisms (SNPs) and a novel SNP A1056G were identified. Then we examined these three SNPs in 171 HCC samples and 162 normal liver samples. However, statistic analysis showed none of these SNPs was statistically significant for association with HCC. In conclusion, our data suggest that PTCH is involved in early stage tumor development and the Hh pathway in Chinese HCC is activated by ligand expression but not by mutation.