[Show abstract][Hide abstract] ABSTRACT: X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1), a XIAP-binding protein, is a tumor suppressor gene. XAF1 was silent or expressed lowly in most human malignant tumors. However, the role of XAF1 in hepatocellular carcinoma (HCC) remains unknown. In this study, we investigated the effect of XAF1 on tumor growth and angiogenesis in hepatocellular cancer cells. Our results showed that XAF1 expression was lower in HCC cell lines SMMC-7721, Hep G2 and BEL-7404 and liver cancer tissues than that in paired non-cancer liver tissues. Adenovirus-mediated XAF1 expression (Ad5/F35-XAF1) significantly inhibited cell proliferation and induced apoptosis in HCC cells in dose- and time- dependent manners. Infection of Ad5/F35-XAF1 induced cleavage of caspase -3, -8, -9 and PARP in HCC cells. Furthermore, Ad5/F35-XAF1 treatment significantly suppressed tumor growth in a xenograft model of liver cancer cells. Western Blot and immunohistochemistry staining showed that Ad5/F35-XAF1 treatment suppressed expression of vascular endothelial growth factor (VEGF), which is associated with tumor angiogenesis, in cancer cells and xenograft tumor tissues. Moreover, Ad5/F35-XAF1 treatment prolonged the survival of tumor-bearing mice. Our results demonstrate that XAF1 inhibits tumor growth by inducing apoptosis and inhibiting tumor angiogenesis. XAF1 may be a promising target for liver cancer treatment.
[Show abstract][Hide abstract] ABSTRACT: Bone marrow-derived myofibroblasts (BMFs) have been shown to promote tumor growth. Here, we found that BMFs or BMF conditioned medium (BMF-CM) induced cancer stem cell-like sphere formation of colon cancer cells. The co-cultured BMFs, but not co-cultured cancer cells, expressed higher levels of IL-6 than BMFs or cancer cells cultured alone. Anti-mouse IL-6 neutralizing antibody, JAK2 inhibitors and STAT3 knockdown in mouse cancer cells reduced BMF- and BMF-CM-induced sphere formation of colon cancer cells. When co-injected, BMFs significantly enhanced tumorigenesis of colon cancer cells in mice. Our results demonstrate that BMFs promote tumorigenesis via the activation of the IL-6/JAK2/STAT3 pathway.
[Show abstract][Hide abstract] ABSTRACT: Bleomycin causes acute lung injury through production of reactive species and initiation of inflammation. Previous work has shown alteration to the production of reactive oxygen species results in attenuation of injury. Vitamin E, in particular, γ-tocopherol, isoform, has the potential to scavenge reactive oxygen and nitrogen species. This study examines the utility of dietary supplementation with tocopherols in reducing bleomycin-mediated acute lung injury. Male C57BL6/J mice were intratracheally instilled with PBS or 2 units/kg bleomycin. Animals were analyzed 3 and 8 days post instillation at the cellular, tissue, and organ levels. Results showed successful delivery of tocopherols to the lung via dietary supplementation. Also, increases in reactive oxygen and nitrogen species due to bleomycin are normalized in those mice fed tocopherol diet. Injury was not prevented but inflammation progression was altered, in particular macrophage activation and function. Inflammatory scores based on histology demonstrate limited progression of inflammation in those mice treated with bleomycin and fed tocopherol diet compared to control diet. Upregulation of enzymes and cytokines involved in pro-inflammation were limited by tocopherol supplementation. Day 3 functional changes in elastance in response to bleomycin are prevented, however, 8 days post injury the effect of the tocopherol diet is lost. The effect of tocopherol supplementation upon the inflammatory process is demonstrated by a shift in the phenotype of macrophage activation. The effect of these changes on resolution and the progression of pulmonary fibrosis has yet to be elucidated.
[Show abstract][Hide abstract] ABSTRACT: Myeloid-derived suppressor cells (MDSC) accumulate in the spleen and tumors and contribute to tumor growth, angiogenesis, and progression. In this study, we examined the effects of curcumin on the activation and differentiation of MDSCs, their interaction with human cancer cells, and related tumor growth. Treatment with curcumin in the diet or by intraperitoneal injection significantly inhibited tumorigenicity and tumor growth, decreased the percentages of MDSCs in the spleen, blood, and tumor tissues, reduced interleukin (IL)-6 levels in the serum and tumor tissues in a human gastric cancer xenograft model and a mouse colon cancer allograft model. Curcumin treatment significantly inhibited cell proliferation and colony formation of cancer cells and decreased the secretion of murine IL-6 by MDSCs in a coculture system. Curcumin treatment inhibited the expansion of MDSCs, the activation of Stat3 and NF-κB in MDSCs, and the secretion of IL-6 by MDSCs, when MDSCs were cultured in the presence of IL-1β, or with cancer cell- or myofibroblast-conditioned medium. Furthermore, curcumin treatment polarized MDSCs toward a M1-like phenotype with an increased expression of CCR7 and decreased expression of dectin 1 in vivo and in vitro. Our results show that curcumin inhibits the accumulation of MDSCs and their interaction with cancer cells and induces the differentiation of MDSCs. The induction of MDSC differentiation and inhibition of the interaction of MDSCs with cancer cells are potential strategies for cancer prevention and therapy.
Cancer Prevention Research 02/2012; 5(2):205-15. · 4.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Autophagy is designated as type II programmed cell death and may confer a tumor-suppressive function. Our previous studies have shown that XIAP-associated factor 1 (XAF1) induced apoptosis and inhibited tumor growth in gastric cancer cells. In this study, we investigated the effect of XAF1 on the induction of autophagy in gastric cancer cells. We found that adenovirus vector-mediated XAF1 (adeno-XAF1) expression markedly induced autophagy, upregulated the level of Beclin-1 and inhibited phospho-Akt and phospho-p70S6K in gastric cancer cells. The downregulation of Beclin 1 or 3-methyladenine treatment suppressed adeno-XAF1-induced autophagy, but significantly enhanced adeno-XAF1-induced apoptosis. A pan-caspase inhibitor prevented adeno-XAF1-induced apoptosis, but significantly increased adeno-XAF1-induced autophagy. Furthermore, adeno-XAF1 induced autophagy in xenograft tumor and inhibited tumor growth. Our results document that adeno-XAF1 induces autophagy through upregulation of Beclin 1 expression and inhibition of Akt/p70S6K pathway, and reveal a new mechanism of XAF1 tumor suppression.
Cancer letters 11/2011; 310(2):170-80. · 5.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: IFN-γ mediates responses to bacterial infection and autoimmune disease, but it is also an important tumor suppressor. It is upregulated in the gastric mucosa by chronic Helicobacter infection; however, whether it plays a positive or negative role in inflammation-associated gastric carcinogenesis is unexplored. To study this question, we generated an H(+)/K(+)-ATPase-IFN-γ transgenic mouse that overexpresses murine IFN-γ in the stomach mucosa. In contrast to the expected proinflammatory role during infection, we found that IFN-γ overexpression failed to induce gastritis and instead inhibited gastric carcinogenesis induced by interleukin-1beta (IL-1β) and/or Helicobacter infection. Helper T cell (Th) 1 and Th17 immune responses were inhibited by IFN-γ through Fas induction and apoptosis in CD4 T cells. IFN-γ also induced autophagy in gastric epithelial cells through increased expression of Beclin-1. Finally, in the gastric epithelium, IFN-γ also inhibited IL-1β- and Helicobacter-induced epithelial apoptosis, proliferation, and Dckl1(+) cell expansion. Taken together, our results suggest that IFN-γ coordinately inhibits bacterial infection and carcinogenesis in the gastric mucosa by suppressing putative gastric progenitor cell expansion and reducing epithelial cell apoptosis via induction of an autophagic program.
Cancer Research 06/2011; 71(12):4247-59. · 9.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carcinoma-associated fibroblasts (CAFs) that express α-smooth muscle actin (αSMA) contribute to cancer progression, but their precise origin and role are unclear. Using mouse models of inflammation-induced gastric cancer, we show that at least 20% of CAFs originate from bone marrow (BM) and derive from mesenchymal stem cells (MSCs). αSMA+ myofibroblasts (MFs) are niche cells normally present in BM and increase markedly during cancer progression. MSC-derived CAFs that are recruited to the dysplastic stomach express IL-6, Wnt5α and BMP4, show DNA hypomethylation, and promote tumor growth. Moreover, CAFs are generated from MSCs and are recruited to the tumor in a TGF-β- and SDF-1α-dependent manner. Therefore, carcinogenesis involves expansion and relocation of BM-niche cells to the tumor to create a niche to sustain cancer progression.
Cancer cell 02/2011; 19(2):257-72. · 25.29 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Colon cancer is one of the most common cancers. Survivin is overexpressed in human colon cancer and correlate with chemoresistance, angiogenesis and poor prognosis. Oxaliplatin, a platinum derivative cancer drug, has been used for treating human colorectal cancers. In the present study, we investigated the effect of the adeno-associated virus (AAV)-mediated survivin mutant Thr34Ala [rAAV-Sur-Mut(T34A)] on colon cancer growth. Infection with rAAV-Sur-Mut(T34A) inhibited cell proliferation, induced apoptosis and mitotic catastrophe, and sensitized colon cancer cells to chemotherapeutic drugs in vitro. Treatment with rAAV-Sur-Mut(T34A) significantly induced apoptosis, reduced angiogenesis and inhibited colon cancer growth in vivo. More importantly, rAAV-Sur-Mut(T34A) treatment strongly enhanced the anti-tumor activity of oxaliplatin and prolonged animal survival. Thus, the use of rAAV-Sur-Mut(T34A) in combination with chemotherapy may be a promising strategy for colon cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: The risk of pancreatic cancer is increased in both Snus (the Swedish variant of oral smokeless tobacco) users and, to a greater extent, in cigarette smokers. Concurrent chronic pancreatitis further increases the risk in cigarette smokers. Little is known about the mechanism by which cigarette smoke or Snus increase the risk of pancreatic cancer in individuals with chronic pancreatitis. This study examined the carcinogenic effects of an aqueous extract of cigarette smoke (tobacco smoke, TS) or Snus in an Elastase-IL-1beta transgenic mouse model of chronic pancreatitis. Both transgenic and wild-type (WT) mice were fed diluted TS water or Snus-containing diet for up to 15 months, and monitored for phenotypic and molecular changes in the pancreas. Both TS- and Snus-treated Elastase-IL-1beta mice, but not WT mice, developed significant pancreatic ductal epithelial flattening and severe glandular atrophy compared with untreated transgenic mice. Ductal epithelial cells displayed a high proliferative index, minimal apoptosis, and induction of COX-2 in the setting of chronic inflammation. Up-regulation of TNF-alpha correlated with the onset of severe glandular atrophy. In comparison with Snus-treated mice, TS-Elastase-IL-1beta mice had an earlier onset and a greater extent of phenotypic changes, which were associated with up-regulation of TNF-alpha and increased expression of IL-6, TGF-beta, and SDF-1. Collectively, these findings provide new insights into the mechanism by which tobacco products are likely to promote carcinogenesis in the setting of chronic pancreatitis.
[Show abstract][Hide abstract] ABSTRACT: XIAP-associated factor 1 (XAF1) antagonizes the anticaspase activity of XIAP (X-linked inhibitor of apoptosis) and functions as a tumor suppressor in colon cancer. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is known as a potential anticancer agent. In this study, the synergistic effect of XAF1 and TRAIL on colon cancer growth was investigated.
Adeno-XAF1 virus was generated and purified. Cell apoptosis was detected by flow-cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. Protein expression of the different genes was determined by Western blot analysis. Tumorigenesis and tumor growth were assessed in subcutaneous nude mouse xenograft experiments.
Stable overexpression of XAF1-sensitized colon cancer cells to TRAIL-induced apoptosis significantly increased the activity of caspase 3, 7, 8, and 9; released cytochrome c; and down-regulated XIAP, survivin, and c-IAP-2. The restoration of XAF1 expression mediated by adenovirus (adeno-XAF1) directly induced apoptosis, and synergized TRAIL-induced apoptosis in colon cancer cells. Ex vivo transduction of adeno-XAF1 suppressed colon cancer formation in vivo. Furthermore, adeno-XAF1 treatment of mice significantly inhibited tumor growth, strongly enhanced TRAIL-induced apoptosis and antitumor activity in colon cancer xenograft models in vivo, and markedly prolonged the survival. Notably, the combined treatment with adeno-XAF1 and TRAIL completely eradicated the established tumors without detectable toxicity in normal tissue.
The combined restoration of XAF1 expression and TRAIL treatment may be a potent strategy for colon cancer therapy.
Cancer 03/2010; 116(5):1252-63. · 4.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent studies with Helicobacter-infected mice have shown that bone marrow-derived cells can repopulate the gastric epithelium and progress to cancer. However, it has not been established which cellular subset can potentially contribute to the epithelium. The aim of this study was to investigate the ability of bone marrow-derived mesenchymal stem cells (MSCs) that express cytokeratin 19 (K19) to contribute to the gastric epithelium. MSCs cultures were established from whole bone marrow and expression of K19 was detected in a minority (1 of 13) of clones by real-time PCR and immunostaining. Transfection of a K19-green fluorescent protein (GFP) vector and isolation of GFP-expressing colonies generated high K19-expressing MSC clones (K19GFPMSC). Incubation of MSCs with gastric tissue extract markedly induced mRNA expression of gastric phenotypic markers and was observed to a greater extent in K19GFPMSCs compared with parental MSCs and mock transfectants. Both K19GFPMSCs and GFP-labeled control MSCs gave rise to gastric epithelial cells after injection into the murine stomach. In addition, after blastocyst injections, K19GFPMSCs gave rise to GFP-positive gastric epithelial cells in all 13 pups, whereas only 3 of 10 offspring showed GFP-positive gastric epithelial cells after injection of GFP-labeled control MSCs. Although K19 expression could not be detected in murine whole bone marrow, H. felis infection increased K19-expressing MSCs in the circulation. Taken together, our results show that bone marrow-derived MSCs can contribute to the gastric epithelium. The K19-positive MSC fraction that is induced by chronic H. felis infection appears to be the important subset in this process.
[Show abstract][Hide abstract] ABSTRACT: Overexpression of trefoil factor 2 (TFF2) is associated with increased cell migration, resistance to apoptosis, and possibly increased gastric cancer invasion. Dysregulation of p53 is frequently observed in preneoplastic conditions of the stomach. Here, we investigated the effect of p53 on the expression and function of TFF2 in gastric cancer cell lines. Gene expression was determined by reverse transcription-polymerase chain reaction, and promoter activity was assessed by dual luciferase reporter assays. Apoptosis was detected by flow cytometry, and cell migration was evaluated by the Boyden chamber assay. Exogenous expression of p53 dose dependently inhibited endogenous TFF2 mRNA, protein, and promoter activity and resulted in induction of cell apoptosis and inhibition of cell migration. Downregulation of TFF2 by small interfering RNA sensitized gastric cancer cells to drug-induced p53-dependent apoptosis. Addition of human TFF2 peptide reversed p53-dependent apoptosis and inhibition of cell migration. The p53-responsive element was mapped to an AP-1-like cis-element at -182 bp upstream of the TFF2 transcription start site. Mutation of this AP-1-like element abrogated p53-mediated inhibition of TFF2 promoter activity. Gel shift and chromatin immunoprecipitation assays demonstrated that c-Jun and c-Fos bind to this AP-1-like element. Ectopic expression of c-Jun/c-Fos or p300 or treatment of cells with phorbol 12-myristate 13-acetate (PMA) stimulated endogenous TFF2 mRNA expression and promoter activity, and p53 inhibited the effects of AP-1 and PMA on TFF2. p53 induces cell apoptosis and inhibits cell migration in part by downregulating TFF2 expression through an AP-1-like site, suggesting that TFF2 may be an important downstream target of p53.
[Show abstract][Hide abstract] ABSTRACT: Chronic pancreatitis is a significant cause of morbidity and a known risk factor for pancreatic adenocarcinoma. Interleukin-1beta is a proinflammatory cytokine involved in pancreatic inflammation. We sought to determine whether targeted overexpression of interleukin-1beta in the pancreas could elicit localized inflammatory responses and chronic pancreatitis.
We created a transgenic mouse model (elastase sshIL-1beta) in which the rat elastase promoter drives the expression of human interleukin-1beta. Mice were followed up for up to 2 years. Pancreata of elastase sshIL-1beta mice were analyzed for chronic pancreatitis-associated histologic and molecular changes. To study the potential effect of p53 mutation in chronic pancreatitis, elastase sshIL-1beta mice were crossed with p53(R172H) mice.
Three transgenic lines were generated, and in each line the pancreas was atrophic and occasionally showed dilation of pancreatic and biliary ducts secondary to proximal fibrotic stenosis. Pancreatic histology showed typical features of chronic pancreatitis. There was evidence for increased acinar proliferation and apoptosis, along with prominent expression of tumor necrosis factor-alpha; chemokine (C-X-C motif) ligand 1; stromal cell-derived factor 1; transforming growth factor-beta1; matrix metallopeptidase 2, 7, and 9; inhibitor of metalloproteinase 1; and cyclooxygenase 2. The severity of the lesions correlated well with the level of human interleukin-1beta expression. Older mice displayed acinar-ductal metaplasia but did not develop mouse pancreatic intraepithelial neoplasia or tumors. Elastase sshIL-1beta*p53(R172H/+) mice had increased frequency of tubular complexes, some of which were acinar-ductal metaplasia.
Overexpression of interleukin-1beta in the murine pancreas induces chronic pancreatitis. Elastase sshIL-1beta mice consistently develop severe chronic pancreatitis and constitute a promising model for studying chronic pancreatitis and its relationship with pancreatic adenocarcinoma.
[Show abstract][Hide abstract] ABSTRACT: X-linked inhibitor of apoptosis protein (XIAP)-associated factor 1 (XAF1) antagonizes the anti-caspase activity of XIAP. XAF1 messenger RNA is present in normal tissues but undetectable in various cancers and thus poses a potential tumor suppressor gene. The aim of this study was to examine the novel pattern of methylation of XAF1 in gastric and colon cancers and locate the important CpG sites for transcriptional regulation and tumor progression.
XAF1 expression was detected by reverse-transcription polymerase chain reaction (PCR) and Western blot analysis. Four different fragments around the transcription start site of XAF1 were cloned and examined putative promoter activities by luciferase reporter assay. Each CpG site in fragment F291 was mutated by site-directed mutagenesis technique, and the change of promoter activity of this fragment was detected by luciferase reporter assay. Methylation status of XAF1 was determined by methylation-specific PCR (MSP) and bisulfite DNA sequencing PCR analysis.
Down-regulation of XAF1 in association with hypermethylation was detected in 3 of 4 human gastric cancer cell lines and 6 of 8 colon cancer cell lines. Of the 4 promoter fragments, F291 showed the highest promoter activity, which could be down-regulated obviously by the mutation of particular CpG sites. Moreover, aberrant hypermethylation of these important CpG sites was strongly associated with the development of gastric and colon cancers.
A cluster of methylated CpG sites instead of CpG islands located in the promoter area resulted in gene silencing of XAF1, and CpGs at -2nd, -1st, and +3rd positions are functionally more important in its transcriptional regulation.
[Show abstract][Hide abstract] ABSTRACT: Aspirin-induced apoptosis is one of the important mechanisms for its antitumour effect against gastric cancer. We aimed at investigating the involvement of bcl-2 family members in the apoptotic pathway in gastric cancer. Gastric cancer cell line AGS and MKN-45 were observed as to cell growth inhibition and induction of apoptosis in response to treatment with aspirin. Cell proliferation was measured by MTT assay. Apoptosis was determined by 4'-6-diamidino-2-phenylindole staining. Protein expression was determined by western blotting. We showed that aspirin activated caspase-8, caspase-9 and capase-3, cleaved and translocated Bid, induced a conformational change in and translocation of Bax and cytochrome c release. In addition, suppression of caspase-8 with the specific inhibitor z-IETD-fmk, as well as the pan-caspase inhibitor z-VAD-fmk, prevented Bid cleavage and subsequent apoptosis. The caspase inhibitors failed to abolish the effects on Bax activation. In conclusion, our results identify a role of caspase-8/Bid and activation of Bax as a novel mechanism for aspirin-induced apoptosis in gastric cancer.
[Show abstract][Hide abstract] ABSTRACT: Reactivation of survivin expression is involved in carcinogenesis and angiogenesis in colon cancer. Previous in vitro studies showed that mutation of the cysteine residue at position 84 (Cys84Ala) of survivin generates a dominant-negative mutant that triggers mitotic catastrophe and apoptosis. We investigated the therapeutic effect of the adeno-associated virus (AAV)-mediated survivin mutant (Cys84Ala) on colon cancer.
Survivin mutant (Cys84Ala) (Sur-Mut(Cys84Ala)) was cloned into the AAV expression vector pAM/CAG-WPRE.poly(A) to generate recombinant AAV-Sur-Mut(Cys84Ala) virus. Cell proliferation, apoptosis, mitotic catastrophe, and tumor growth were measured in vitro and in vivo.
Transduction of colon cancer cells with rAAV-Sur-Mut(Cys84Ala) inhibited cell proliferation and induced apoptosis and mitotic catastrophe in vitro. rAAV-Sur-Mut(Cys84Ala) sensitized colon cancer cells to chemotherapeutic drugs. Furthermore, expression of survivin mutant mediated by AAV inhibited tumorigenesis in colon cancer cells. Intratumoral injection of rAAV-Sur-Mut(Cys84Ala) significantly induced apoptosis and mitotic catastrophe and inhibited angiogenesis and tumor growth in a colon cancer xenograft model in vivo. No obvious cytotoxicity to other tissues was observed. More importantly, rAAV-Sur-Mut(Cys84Ala) expression strongly enhanced the antitumor activity of 5-Fluorouracil (5-FU), resulting in regression of established tumors.
Our results showed that rAAV-Sur-Mut(Cys84Ala) induced apoptosis and mitotic catastrophe and inhibited tumor angiogenesis and tumor growth. Thus, use of AAV-mediated survivin mutant (Cys84Ala) is a promising strategy in colon cancer gene therapy.
[Show abstract][Hide abstract] ABSTRACT: Aspirin exerts antitumor effect partly through blocking tumor promoter-induced activator protein-1 (AP-1) activation. The aim of this study is to determine how specific COX-2 inhibitor SC-236 mediates antitumor effect by modulation of AP-1-signaling pathway.
AP-1 transcriptional activity and DNA-binding activity were detected by luciferase reporter assay and gel shift assay, separately. Mitogen-activated protein kinase (MAPK) activation was determined by Western blot and in vitro kinase assay. Antisense oligonucleotide against c-Jun-N-terminal kinase (JNK) was used to suppress JNK expression.
We showed that SC-236 inhibited 12-O-tetradecanoylphorbol-13-acetate (PMA)-induced cell transformation in a dose-dependent manner in JB6 cells. At a dose range (12.5-50 micromol/L) that inhibited cell transformation, SC-236 also inhibited anchorage-independent cell growth and AP-1-activation in 3 gastric cancer cells, independent of COX-prostaglandin synthesis. SC-236 down-regulated c-Jun-NH2-terminal kinase phosphorylation and activity. Suppression of JNK activity reversed the inhibitory effect on AP-1 activity by SC-236 and suppressed gastric cancer cell growth, indicating that the inhibitory effect of SC-236 on AP-1 activation and cell growth was through interaction with JNK.
The inhibitory effect on JNK-c-Jun/AP-1 activation contributes to the antitumor effect of COX-2-specific inhibitor, and inhibition of JNK activation may have a therapeutic benefit against gastric cancer.