Early modulation of gene expression used as a biomarker for chemoprevention in a preclinical model of colon carcinogenesis

The inhibitory effect of human DEFA5 in growth of gastric cancer by targeting BMI1

Defensins, a class of small cysteine‐rich cationic polypeptides across cellular life, are identified as antimicrobial compounds that display direct antimicrobial and immune signaling activities that are involved in the host defense. In addition to their roles in the innate immune system, accumulating studies have reported that some members of defensins are expressed and involved in some cancer cells, such as colon cancer, colorectal cancer, lung cancer and renal cell carcinomas. However, the roles of α‐Defensin 5 (DEFA5) in tumorigenesis and development remain unknown. In the present study, bioinformatics analysis and quantitative PCR results showed that the expression level of DEFA5 was dramatically downregulated in human gastric cancer. Overexpression of human DEFA5 in gastric cancer cell lines SGC7901 and BGC823 effectively diminished cell proliferation and reduced the colony forming ability. Moreover, DEFA5 overexpression induced cell cycle arrest by significantly increasing the number of G1‐phase cells. Consistently, in vivo tumor formation experiments in nude mice showed the suppression of the tumor growth by DEFA5 overexpression, suggesting an inhibitory effect of DEFA5 in gastric cancer. Mechanistically, DEFA5 directly binds to BMI1, which subsequently decreased its binding at the CDKN2a locus and upregulated the expression of 2 cyclin‐dependent kinase inhibitors, p16 and p19. Taken together, we concluded that DEFA5 showed an inhibitory effect in gastric cancer cell growth and may serve as a potential tumor suppressor in gastric cancer.

Studies on the Interaction of Tumor-Derived HD5 Alpha Defensins with Adenoviruses and Implications for Oncolytic Adenovirus Therapy

Defensins are small antimicrobial peptides capable of neutralizing human adenovirus (HAdV) in vitro by binding capsid proteins and blocking endosomal escape of virus. In humans, the alpha defensin HD5 is produced by specialized epithelial cells of the gastrointestinal and genito-urinary tracts. Here, we demonstrate, using patient biopsy specimens, that HD5 is also expressed as an active, secreted peptide by epithelial ovarian and lung cancer cells in situ This finding prompted us to study the role of HD5 in infection and spread of replication-competent, oncolytic HAdV type 3 (HAdV3). HAdV3 produces large amounts of penton-dodecahedra (PtDd), virus-like particles, during replication. We have previously shown that PtDd are involved in opening epithelial junctions, thus facilitating lateral spread of de novo-produced virions. Here, we describe a second function of PtDd, namely, the blocking of HD5. A central tool to prove that viral PtDd neutralize HD5 and support spread of progeny virus was an HAdV3 mutant virus in which formation of PtDd was disabled (mut-Ad3GFP, where GFP is green fluorescent protein). We demonstrated that viral spread of mut-Ad3GFP was blocked by synthetic HD5 whereas that of the wild-type (wt) form (wt-Ad3GFP) was only minimally impacted. In human colon cancer Caco-2 cells, induction of cellular HD5 expression by fibroblast growth factor 9 (FGF9) significantly inhibited viral spread and progeny virus production of mut-Ad3GFP but not of wt-Ad3GFP. Finally, the ectopic expression of HD5 in tumor cells diminished the in vivo oncolytic activity of mut-Ad3GFP but not of wt-Ad3GFP. These data suggest a new mechanism of HAdV3 to overcome innate antiviral host responses. Our study has implications for oncolytic adenovirus therapy.IMPORTANCE Previously, it has been reported that human defensin HD5 inactivates specific human adenoviruses by binding to capsid proteins and blocking endosomal escape of virus. The central new findings described in our manuscript are the following: (i) the discovery of a new mechanism used by human adenovirus serotype 3 to overcome innate antiviral host responses that is based on the capacity of HAdV3 to produce subviral penton-dodecahedral particles that act as decoys for HD5, thus preventing the inactivation of virus progeny produced upon replication; (ii) the demonstration that ectopic HD5 expression in cancer cells decreases the oncolytic efficacy of a serotype 5-based adenovirus vector; and (iii) the demonstration that epithelial ovarian and lung cancers express HD5. The study improves our understanding of how adenoviruses establish infection in epithelial tissues and has implications for cancer therapy with oncolytic adenoviruses.

Characterization of Changes in Global Genes Expression in the Distal Colon of Loperamide-Induced Constipation SD Rats in Response to the Laxative Effects of Liriope platyphylla

To characterize the changes in global gene expression in the distal colon of constipated SD rats in response to the laxative effects of aqueous extracts of Liriope platyphylla (AEtLP), including isoflavone, saponin, oligosaccharide, succinic acid and hydroxyproline, the total RNA extracted from the distal colon of AEtLP-treated constipation rats was hybridized to oligonucleotide microarrays. The AEtLP treated rats showed an increase in the number of stools, mucosa thickness, flat luminal surface thickness, mucin secretion, and crypt number. Overall, compared to the controls, 581 genes were up-regulated and 216 genes were down-regulated by the constipation induced by loperamide in the constipated rats. After the AEtLP treatment, 67 genes were up-regulated and 421 genes were down-regulated. Among the transcripts up-regulated by constipation, 89 were significantly down-regulated and 22 were recovered to the normal levels by the AEtLP treatment. The major genes in the down-regulated categories included Slc9a5, klk10, Fgf15, and Alpi, whereas the major genes in the recovered categories were Cyp2b2, Ace, G6pc, and Setbp1. On the other hand, after the AEtLP treatment, ten of these genes down-regulated by constipation were up-regulated significantly and five were recovered to the normal levels. The major genes in the up-regulated categories included Serpina3n, Lcn2 and Slc5a8, whereas the major genes in the recovered categories were Tmem45a, Rerg and Rgc32. These results indicate that several gene functional groups and individual genes as constipation biomarkers respond to an AEtLP treatment in constipated model rats.

Evaluation of chemopreventive effects of Acanthus ilicifolius against azoxymethane-induced aberrant Crypt Foci in the rat colon

Background

Acanthus ilicifolius, a mangrove medicinal plant, is traditionally used to treat a variety of diseases. The aim of this research is to assess the chemoprotective outcomes of A. ilicifolius ethanolic extract against azoxymethane (AOM) induced colonic aberrant crypt foci (ACF) in rats.

Methodology/Principal Findings

In our study, rats were arranged in to five groups. Rats in the normal control group were given subcutaneous injections of normal saline once weekly for 2 weeks. The AOM control, reference and treatment groups were given subcutaneous injection of AOM, 15 mg/kg body weight, once weekly for 2 weeks each. The reference group was treated with 35 mg/kg 5-Fluorouracil via intraperitoneal injection once weekly for 8 weeks, and the treatment groups were administered by gavage with 250 and 500 mg/kg A. ilicifolius extract daily for 8 weeks. Both normal and AOM control groups received the vehicle; 10% Tween-20 only.

Rats treated with 250 mg/kg and 500 mg/kg of A. ilicifolius extracts showed a decrease in the mean number of ACF by 65% and 53%, respectively. Those fed with A. ilicifolius showed significantly decreased multiplicity of ACF formations when compared with the results from the AOM control group. The 250 mg/kg A. ilicifolius treatment group showed significant decreases in lipid peroxidation MDA levels when compared with the AOM control group. In immunohistochemistry staining, the proliferating nuclear cell antigen (PCNA)-positive cells were significantly higher in the AOM control group than in the A. ilicifolius-treated groups. RT-PCR showed that A. ilicifolius caused a change in the regulation of apoptosis-related genes expression.

Conclusion/Significance

The results of the current study show that AOM-treated rats receiving oral exposure to A. ilicifolius demonstrated a significant decrease in the number of ACF in the colon when compared to AOM-treated rats receiving vehicle only. A ilicifolius may be an effective herbal approach for the prevention of AOM-induced ACF in the rat colon.

Diet-induced obesity promotes colon tumor development in azoxymethane-treated mice

Obesity is an important risk factor for colon cancer in humans, and numerous studies have shown that a high fat diet enhances colon cancer development. As both increased adiposity and high fat diet can promote tumorigenesis, we examined the effect of diet-induced obesity, without ongoing high fat diet, on colon tumor development. C57BL/6J male mice were fed regular chow or high fat diet for 8 weeks. Diets were either maintained or switched resulting in four experimental groups: regular chow (R), high fat diet (H), regular chow switched to high fat diet (RH), and high fat diet switched to regular chow (HR). Mice were then administered azoxymethane to induce colon tumors. Tumor incidence and multiplicity were dramatically smaller in the R group relative to all groups that received high fat diet at any point. The effect of obesity on colon tumors could not be explained by differences in aberrant crypt foci number. Moreover, diet did not alter colonic expression of pro-inflammatory cytokines tumor necrosis factor-α, interleukin-6, interleukin-1β, and interferon-γ, which were measured immediately after azoxymethane treatment. Crypt apoptosis and proliferation, which were measured at the same time, were increased in the HR relative to all other groups. Our results suggest that factors associated with obesity – independently of ongoing high fat diet and obesity – promote tumor development because HR group animals had significantly more tumors than R group, and these mice were fed the same regular chow throughout the entire carcinogenic period. Moreover, there was no difference in the number of aberrant crypt foci between these groups, and thus the effect of obesity appears to be on subsequent stages of tumor development when early preneoplastic lesions transition into adenomas.

Silibinin, a natural flavonoid, modulates the early expression of chemoprevention biomarkers in a preclinical model of colon carcinogenesis

The flavonolignan silibinin, the major biologically active compound of the milk thistle (Silybum marianum), has been shown to possess anticancer properties in a variety of epithelial cancers. The present study investigated the potential of silibinin as a chemopreventive agent in colon carcinogenesis. The rat azoxymethane (AOM)-induced colon carcinogenesis model was used because of its molecular and clinical similarities to sporadic human colorectal cancer. One week after AOM injection (post-initiation), Wistar rats received daily intragastric feeding of 300 mg silibinin/kg body weight per day until their sacrifice after 7 weeks of treatment. Silibinin-treated rats exhibited a 2-fold reduction in the number of AOM-induced hyperproliferative crypts and aberrant crypt foci in the colon compared to AOM-injected control rats receiving the vehicle. Silibinin-induced apoptosis in the colon mucosal cells was demonstrated by flow cytometry after propodium iodide staining and by colorimetric measurement of caspase-3 activity. Mechanisms involved in silibinin-induced apoptosis included the downregulation of the anti-apoptotic protein Bcl-2 and upregulation of the pro-apoptotic protein Bax, inverting the Bcl-2/Bax ratio to <1. This modulation already takes place at the mRNA expression level as shown by real-time RT-PCR. Furthermore, silibinin treatment significantly (P<0.01) decreased the genetic expression of biomarkers of the inflammatory response such as IL1β, TNFα and their downstream target MMP7, all of them shown to be upregulated during colon carcinogenesis. The downregulation of MMP7 protein was confirmed by western blot analysis. The present findings show the ability of silibinin to shift the disturbed balance between cell renewal and cell death in colon carcinogenesis in rats previously injected with the carcinogen AOM. Silibinin administered via intragastric feeding exhibited potent pro-apoptotic, anti-inflammatory and multi-targeted effects at the molecular level. The effective reduction of preneoplastic lesions by silibinin supports its use as a natural agent for colon cancer chemoprevention.

Treatment of pancreatic cancer using an oncolytic virus harboring the lipocalin-2 gene

BACKGROUND

The 5-year survival rate for patients with pancreatic cancer is <5%, and it is always resistant to the current chemoradiotherapy. Therefore, new, effective agents for the treatment of pancreatic cancer are urgently needed. The promising strategy of cancer-targeting gene virotherapy (CTGVT) has demonstrated great anticancer potential. The objective of the current study was to determine whether 1 CTGVT approach, oncolytic virus (OV)-harboring lipocalin-2, is capable of treating pancreatic cancer.

METHODS

Tissue microarrays were constructed to detect the expression of lipocalin-2 in 60 specimens of pancreatic adenocarcinoma. The clinical significance of lipocalin-2 was investigated in an analysis of correlations between lipocalin-2 expression and matched clinical characteristics. A lipocalin-2-expressing OV, ZD55-lipocalin-2, was constructed by deleting the adenoviral protein E1B55kD. The antitumor efficacy and mechanisms of the OV were investigated in pancreatic cancer cells with v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations in vitro and in vivo.

RESULTS

Lipocalin-2 expression was correlated with a good prognosis in patients with pancreatic adenocarcinoma. ZD55-lipocalin-2 dramatically inhibited the growth of pancreatic cancer in vitro and in vivo by inducing cytolysis and caspase-dependent apoptosis.

CONCLUSIONS

Higher lipocalin-2 expression predicted a better prognosis in patients with pancreatic cancer. The results indicated that ZD55-lipocalin-2, which specifically expressed higher levels of lipocalin-2 in tumor cells, may serve as a potent anticancer drug for pancreatic cancer therapy, especially for patients who have pancreatic adenocarcinoma with KRAS mutations.

Correlations of TOP2A gene aberrations and expression of topoisomerase IIα protein and TOP2A mRNA expression in primary breast cancer: a retrospective study of 86 cases using fluorescence in situ hybridization and immunohistochemistry

Our aim in this study was to assess the status of TOP2A gene aberrations (no change/amplification or deletion) and its correlations with topoisomerase IIα (Topo IIα) protein and TOP2A mRNA expression, respectively. TOP2A amplification, Topo IIα protein expression and TOP2A mRNA expression were assessed using samples of 86 cases of breast cancer by fluorescence in fluorescence in situ hybridization, quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Twenty two (22.57%) had amplification/deletion of TOP2A gene. Twenty eight (32.56%) tumor samples were 17q polysomy or monosomy. Topo IIα protein was expressed in 57 cases (66.27%, 57/86): 22 cases (38.62%, 22/57) and 35 cases (61.40%, 35/57) had amplification/deletion and no change of TOP2A gene, respectively. These three groups showed significant differences by one-way analysis of variance (P < 0.001). The average Ct values of TOP2A mRNA expression in the tumors with deletion, amplification and no change of TOP2A gene were 27.00, 27.33 and 31.66, respectively. We demonstrated that the TOP2A gene was amplified or deleted in breast cancer, with a significant correlation with high expressions of Topo IIα protein and TOP2A mRNA expression. Ki-67 expression index (mean = 14.9) decreased significantly in cases wherein TOP2A gene had no change and Her2/neu protein expression was weakly positive (0-1+, P < 0.001).