Abstract 1448: Unraveling the oncogenic pathway of serrated polyposis syndrome driven by RNF43 germline mutation

Serrated polyps can arise in a sporadic or familial polyposis setting and predispose to colorectal cancer (CRC). Recently, we have identified RNF43 germline mutation in a family with Serrated Polyposis Syndrome (Yan et al, GUT 2016). The presence of second somatic hit in all serrated polyps examined from members of this family further confirmed the pathogenicity of RNF43 germline mutation. In an attempt to further delineate the global genomic alterations in these serrated polyps, so as to understand the RNF43 driven serrated neoplasia pathway for the development of colorectal cancer, we performed whole exome sequencing (WES) on two sessile serrated adenomas (SSAs) resected from an RNF43 germline mutation carrier, together with the paired blood DNA. Consistent with the results from our previous Sanger sequencing study, WES detected complete inactivation of RNF43 through a 2nd hit somatic mutation, c.461 C>T P154L, or loss of heterozygosity (LOH) in the two SSAs, respectively. We also identified 51 and 58 somatic mutations in the two SSAs, respectively. BRAFV600E mutation was the only shared mutation between the two polyps. Interestingly, each of the SSAs carried a truncating mutation in a histone-methyltransferase gene, either PRDM9 or SETD1B, respectively. Other truncating or deleterious mutations included chromatin modifiers (CHD2, CHD4, TSPYL2) or other genes with methyltransferase activity (TRMT2B, METTL12, METTL14, ECE2). In addition, we found few instances of chromosomal aberration or LOH, apart from a region of LOH at chromosome 17 encompassing RNF43 in one of the SSAs.

Overall, we have revealed the genomic landscape of two sessile serrated adenomas resected from a germline RNF43 mutation carrier. The results confirmed somatic RNF43 2nd hit and BRAFV600E mutation as the key events, along with putative roles for histone methyltransferase, as well as other chromatin modifiers. These findings highlight the potentially important role of an altered chromatin in the oncogenic pathway of serrated neoplasia.

Citation Format: Helen Hoi Ning Yan, Jeffrey C W Lai, Siu Lun Ho, Anthony K W Chan, Wai Yin Tsui, Annie S Y Chan, Siu Tsan Yuen, Suet Yi Leung. Unraveling the oncogenic pathway of serrated polyposis syndrome driven by RNF43 germline mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1448. doi:10.1158/1538-7445.AM2017-1448

Abstract 4378: Gastric cancer organoid culture shows preserved genomic stability in long-term passage

With recent advances in 3D organoid culture techniques, normal epithelial and tumor cells can be directly cultured from clinical specimens in vitro and expanded long-term with a very high success rate. Thus, this constitutes a good platform for various mechanistic functional studies and clinical applications. A previous karyotyping and gene expression profiling study has indicated that organoid culture of normal epithelial cells can be propagated for long periods of time without genomic alterations. However, data on the genomic stability of tumor organoids in long-term culture are not yet available. We have successfully established organoid cultures derived from either primary tumor or lymph node metastasis from 4 gastric cancer patients. For each sample, we performed long-term culture for at least 6 months. DNA was extracted from blood, as well as the early and late passages of these organoids, and submitted for whole-exome sequencing (WES), achieving a mean coverage approaching 50X. Somatic mutations detected in early versus late passage gastric cancer organoids were compared. Furthermore, we examined the organoids for copy number variations based on the coverage and loss of heterozygosity (LOH) information derived from exome sequencing.

We detected between 80 to 228 somatic mutations in the 4 early passage organoids, in which over 84-99% of them were retained during long-term culture. We detected 16, 20, 31 and 98 new mutations in the 4 long-term cultures, respectively. The one case with a substantially large number of new mutations (n=98) appeared to have emerged from a subclone of TP53 wild-type cells in a TP53 mutant tumor. Notably, the C>T mutation was the most dominant mutation spectrum in this case, constituting 48%. Despite the presence of frequent long segment LOH and chromosomal aberrations in early passage organoids, indicating the presence of chromosomal instability, these patterns of aberrations were stably maintained in long-term passage.

Overall, with the current organoid culture protocol, tumor genomes are mostly stably maintained with the accumulation of only a small number of new mutations. Our results indicate that this is a reliable and stable in vitro cell culture model for various cancer-related and clinical studies.

Citation Format: Sarah Siu Kuen Yue, Helen Hoi Ning Yan, Hoi Cheong Siu, Siu Lun Ho, Wai Yin Tsui, Dessy Chan, Annie Shuk Yee Chan, Bernard Chi Hang Lee, Anthony Kin Wang Chan, Suet Yi Leung. Gastric cancer organoid culture shows preserved genomic stability in long-term passage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4378. doi:10.1158/1538-7445.AM2017-4378

Abstract B22: Integrative analysis of DNA methylation and gene expression data reveals complex regulation of gastric cancer

Gastric cancer is a heterogeneous disease where diverse genetic and epigenetic alternations can accumulate in different molecular and histological subtypes. We applied our recently developed causality test between genome-wide DNA methylation and gene expression profiles to three independent cohorts of gastric tumors (97 in Hong Kong University (HKU), 159 in University of Singapore (Singapore) and 365 samples in TCGA stomach adenocarcinoma (TCGA) ). We focused on methylation variations within CpG islands in promoter regions, where global hypermethylation was observed, and identified 37, 62, and 537 key regulators in HKU, Singapore, and TCGA dataset respectively. There were 5 common key regulators (ADHFE1, CDO1, COX7A1, FSTL1, and TCF21) whose methylation variations had high impact on mRNA level changes of large number of downstream genes in all three dataset where different cohorts were profiled using different platforms. When we compared two dataset, there were 5 common key regulators in HKU and Singapore dataset (Fisher's exact test (FET) p-value = 2.9×e-07), 27 common key regulators in HKU and TCGA dataset (FET p-value = 6.8×e-35), and 30 common key regulators in Singapore and TCGA dataset (FET p-value = 1.0×e-29). By combining these, 52 genes were identified as key regulators within at least two dataset. Several of the key regulators were known for the association between their epigenetic disruption and the disease (for example, BNIP3, CDO1, TCF21, ZSCAN18, and so on) while other genes have not implicated in the gastric cancer previously. More interestingly, the downstream genes of these key regulators were significantly overlapped and the directions of correlation with methylation levels were almost same within the three dataset. Further clustering key regulators based on their downstream genes overlaps revealed that there were two distinct groups of downstream genes commonly regulated by these key regulators and the expression of these two groups were anti-correlated. One group was enriched for cell cycle related genes and the other group was enriched for genes involved in immune responses. This result indicates that cell cycle and immune response functions were inversely regulated by methylation variations of the same set of genes. It is worth to note that methylation patterns of some key regulators were subtype dependent and the subtype specific methylation patterns were only observed in tumor samples, but not in adjacent normal tissues. Based on integrative analysis of genome-wide DNA methylation and gene expression profiles within three independent gastric cancer dataset, we identified a set of key regulators whose methylation changes might play a ‘causal' role in the transcriptional regulation associated with the gastric cancer. Further experiments are needed to validate and dissect these putative candidate genes' roles in tumorigenesis and progression of this complex and heterogeneous disease.

Citation Format: Seungyeul Yoo, Suet Yi Leung, Jun Zhu. Integrative analysis of DNA methylation and gene expression data reveals complex regulation of gastric cancer. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr B22.

Genomics Study of Gastric Cancer and Its Molecular Subtypes

Gastric cancer is a heterogeneous disease encompassing diverse morphological (intestinal versus diffuse) and molecular subtypes (MSI, EBV, TP53 mutation). Recent advances in genomic technology have led to an improved understanding of the driver gene mutational profile, gene expression, and epigenetic alterations that underlie each of the subgroups, with therapeutic implications in some of these alterations. There have been attempts to classify gastric cancers based on these genomic features, with an aim to improve prognostication and predict responsiveness to specific drug therapy. The eventual aims of these genomic studies are to develop deep biological insights into the carcinogenic pathway in each of these subtypes. Future large-scale drug screening strategies may then be able to link these genomic features to drug responsiveness, eventually leading to genome-guided personalized medicine with improved cure rates.

A mutational signature in gastric cancer suggests therapeutic strategies

Targeting defects in the DNA repair machinery of neoplastic cells, for example, those due to inactivating BRCA1 and/or BRCA2 mutations, has been used for developing new therapies in certain types of breast, ovarian and pancreatic cancers. Recently, a mutational signature was associated with failure of double-strand DNA break repair by homologous recombination based on its high mutational burden in samples harbouring BRCA1 or BRCA2 mutations. In pancreatic cancer, all responders to platinum therapy exhibit this mutational signature including a sample that lacked any defects in BRCA1 or BRCA2. Here, we examine 10,250 cancer genomes across 36 types of cancer and demonstrate that, in addition to breast, ovarian and pancreatic cancers, gastric cancer is another cancer type that exhibits this mutational signature. Our results suggest that 7–12% of gastric cancers have defective double-strand DNA break repair by homologous recombination and may benefit from either platinum therapy or PARP inhibitors.

Cancer genome analysis has demonstrated that some breast and ovarian tumours show reduced homologous recombination, a feature that can be therapeutically exploited. Here, Alexandrov et al. search for this mutational signature in 36 different cancer types and find that some gastric tumours also harbour this mutational spectrum.

Abstract A35: Genomic characterization of immune escape pathways in gastric cancer

This abstract is being presented as a short talk in the scientific program. A full abstract is printed in the Proffered Abstracts section (PR06) of the Conference Proceedings.

Citation Format: Kai Wang, Suet Yi Leung. Genomic characterization of immune escape pathways in gastric cancer. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A35.

Abstract 179: Regulation of stromal miR-125b on normal colonic epithelial cell renewal and its putative role in tumorigenesis

MicroRNAs (miRNAs) are small non-coding RNAs which exert their effects by post-transcriptionally silencing target mRNAs. Deregulation of miRNA expression is a frequent event in tumorigenesis. MiR-125b is a highly conserved miRNA among various species and is composed of three homologs: hsa-miR-125a, hsa-miR-125b-1 and hsa-miR-125-2. The tumorigenic roles of miR-125b have been studied in various cancers including prostate, colon, glioma etc, and studies have demonstrated that it can act as a tumor suppressor or an oncogene depending on the cellular context. It was characterized as an oncogene in prostate cancer and glioma through down-regulation of pro-apoptotic regulators BAK1 and Bcl-2 modifying factor (BMF), respectively. In colon cancer, a recent clinico-pathological study showed that high expression of miR-125b was associated with tumor invasion and poor prognosis. However, the localization of miR125b in normal colon and tumors is currently unknown. Therefore, we aimed to address the precise expression and the functional role of miR-125b in normal colon, which may provide insight on its potential oncogenic effects during carcinogenesis.

We performed gene expression analysis of miR-125b in normal colon tissues from 16 pairs of colon top versus basal crypts and 4 pairs of crypts versus stroma by real-time RT-PCR. Colon top and basal crypts were microdissected from frozen sections, whereas pure normal crypts and stromal fractions were isolated from freshly resected human colon specimens. We found that miR-125b was significantly enriched in the basal crypts (p<0.001) and the stromal compartment (p = 0.027). Functionally, knockdown of miR-125b by a specific miRCURY antisense oligonucleotide was able to dose dependently inhibit the growth of a normal colon myofibroblast cell line, CCD18, and significantly increase the mRNA level of several key Hedgehog signaling components, including PTCH (p<0.001), SMO (p<0.001), GLI1 (p<0.001) and its downstream target BMP4 (p = 0.017). Finally, we observed a drastic decrease in both the number and size of normal colon organoids when they were co-cultured with myofibroblasts transfected with miR-125b antisense oligonucleotide, as compared with negative control. Our results suggest that expression of miR-125b in the colonic stromal basal crypt compartment functions to inhibit Hedgehog signaling, leading to paracrine enhancement of colon crypt proliferation and stem cell renewal. Thus, given the well-known importance of hedgehog signaling in colon cancer, our findings suggest that dysregulated miR-125b

expression may contribute to carcinogenesis through disruption of this pathway.

Note: This abstract was not presented at the meeting.

Citation Format: Helen H N Yan, Jackie K Y Lau, Annie S Y Chan, Wai Yin Tsui, Tsun Leung Chan, Suet Yi Leung. Regulation of stromal miR-125b on normal colonic epithelial cell renewal and its putative role in tumorigenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 179. doi:10.1158/1538-7445.AM2015-179

Treatment of Gastric Metaplasia or Dysplasia by Endoscopic Radiofrequency Ablation: A Pilot Study

BACKGROUND/AIMS

Patients with gastric intestinal metaplasia and dysplasia are at increased risk of gastric cancer development. We tested the feasibility of using endoscopic radiofrequency ablation for the treatment of dysplasia and metaplasia in the stomach.

METHODOLOGY

Patients who had histologically confirmed low-grade gastric dysplasia or IM were recruited. Endoscopic RFA was performed at 8 week-intervals for a maximum of 3 sessions. All patients were followed up by endoscopy until 12 months post-RFA. The primary outcome was the complete eradication of dysplasia or IM on follow-up. Secondary outcome was adverse events related to RFA.

RESULTS

A total of 12 patients were recruited. Four patients had low-grade dysplasia and the remaining 8 patients had non-dysplastic IM at baseline. At one year after RFA, complete eradication of dysplasia was noted in four patients with low-grade dysplasia (100%). Gastric IM persisted in all patients with baseline metaplasia but the severity of IM improved in 6 (75%) patients. Endoscopic RFA was safe with minimal complications encountered.

CONCLUSIONS

RFA successfully eradicated low-grade dysplasia of the stomach. Gastric IM however persisted after RFA but most patients had evidence of histological improvement on follow up.

Increased microRNA-34b and -34c predominantly expressed in stromal tissues is associated with poor prognosis in human colon cancer

The microRNA-34 family (miR-34a, -34b and -34c) have been reported to be tumor suppressor microRNAs (miRNAs) that are regulated by the TP53 and DNA hypermethylation. However, the expression, regulation, and prognostic value of the miR-34 family have not been systematically studied in colon cancer. To elucidate the roles of miR-34 family in colon carcinogenesis, miR-34a/b/c were measured in tumors and adjacent noncancerous tissues from 159 American and 113 Chinese colon cancer patients using quantitative RT-PCR, and we examined associations between miR-34a/b/c expression with TNM staging, cancer-specific mortality, TP53 mutation status and Affymetrix microarray data. All miR-34 family members were significantly increased in colon tumors, counter to the proposed tumor suppressor role for these miRNAs. Increased miR-34b/c were observed in more advanced tumors in two independent cohorts and increased expression of miR-34b/c was associated with poor cancer-specific mortality. While the expression of miR-34 family was not associated with TP53 mutation status, TP53 transcriptional activity was associated with miR-34a/b/c expression that is consistent with the proposed regulation of miR-34a/b/c by TP53. To examine where the miR-34 family is expressed, the expression of miR-34 family was compared between epitheliums and stromal tissues using laser microdissection technique. The expression of miR-34b/c was increased significantly in stromal tissues, especially in cancer stroma, compared with epithelial tissue. In conclusion, increased miR-34b/c predominantly expressed in stromal tissues is associated with poor prognosis in colon cancer. MiR-34 may contribute to cancer-stromal interaction associated with colon cancer progression.

Bioaccumulation of heavy metals in fish and Ardeid at Pearl River Estuary, China

Sediment, fish (tilapia, Oreochromis mossambicus and snakehead, Channa asiatica), eggs and eggshells of Little Egrets (Egretta garzetta) and Chinese Pond Herons (Ardeola bacchus) were collected from Mai Po Ramsar site of Hong Kong, as well as from wetlands in the Gu Cheng County, Shang Hu County and Dafeng Milu National Nature Reserve of Jiangsu Province, China between 2004 and 2007 (n=3-9). Concentrations of six heavy metals were analyzed, based on inductively coupled plasma optical emission spectrometry (ICP-OES). Significant bioaccumulations of Cd (BAF: 165-1271 percent) were observed in the muscle and viscera of large tilapia and snakehead, suggesting potential health risks to the two bird species, as the fishes are the main preys of waterbirds. Significant (p<0.01) linear relationships were obtained between concentrations of Cd, Cr, Cu, Mn, Pb and Zn in the eggs and eggshells of various Ardeid species, and these regression models were used to extrapolate the heavy metal concentrations in the Ardeid eggs of Mai Po. Extrapolated concentrations are consistent with data in the available literature, and advocate the potential use of these models as a non-invasive sampling method for predicting heavy metal contamination in Ardeid eggs.

Whole-genome sequencing and comprehensive molecular profiling identify new driver mutations in gastric cancer

Gastric cancer is a heterogeneous disease with diverse molecular and histological subtypes. We performed whole-genome sequencing in 100 tumor-normal pairs, along with DNA copy number, gene expression and methylation profiling, for integrative genomic analysis. We found subtype-specific genetic and epigenetic perturbations and unique mutational signatures. We identified previously known (TP53, ARID1A and CDH1) and new (MUC6, CTNNA2, GLI3, RNF43 and others) significantly mutated driver genes. Specifically, we found RHOA mutations in 14.3% of diffuse-type tumors but not in intestinal-type tumors (P < 0.001). The mutations clustered in recurrent hotspots affecting functional domains and caused defective RHOA signaling, promoting escape from anoikis in organoid cultures. The top perturbed pathways in gastric cancer included adherens junction and focal adhesion, in which RHOA and other mutated genes we identified participate as key players. These findings illustrate a multidimensional and comprehensive genomic landscape that highlights the molecular complexity of gastric cancer and provides a road map to facilitate genome-guided personalized therapy.

Application of a 5-tiered scheme for standardized classification of 2,360 unique mismatch repair gene variants in the InSiGHT locus-specific database

The clinical classification of hereditary sequence variants identified in disease-related genes directly affects clinical management of patients and their relatives. The International Society for Gastrointestinal Hereditary Tumours (InSiGHT) undertook a collaborative effort to develop, test and apply a standardized classification scheme to constitutional variants in the Lynch syndrome-associated genes MLH1, MSH2, MSH6 and PMS2. Unpublished data submission was encouraged to assist in variant classification and was recognized through microattribution. The scheme was refined by multidisciplinary expert committee review of the clinical and functional data available for variants, applied to 2,360 sequence alterations, and disseminated online. Assessment using validated criteria altered classifications for 66% of 12,006 database entries. Clinical recommendations based on transparent evaluation are now possible for 1,370 variants that were not obviously protein truncating from nomenclature. This large-scale endeavor will facilitate the consistent management of families suspected to have Lynch syndrome and demonstrates the value of multidisciplinary collaboration in the curation and classification of variants in public locus-specific databases.

Biota-sediment accumulation factor (BSAF), bioaccumulation factor (BAF), and contaminant levels in prey fish to indicate the extent of PAHs and OCPs contamination in eggs of waterbirds

Samples of pond sediment, fish, and shrimp were collected from the Ramsar site at Mai Po marshes, Hong Kong (south China), and samples of pond sediment, fish, and shrimp, as well as eggs of water birds (Chinese Pond Herons (Ardeola bacchus) and Little Egrets (Egretta garzetta)), were collected from two smaller wetland sites at Jiangsu Province (mid-China), between 2004 and 2007. Accumulation levels of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the biota were used to calculate biota-sediment accumulation factor (BSAF) and bioaccumulation factor (BAF). For fish and shrimp, BSAFs of OCPs (3.8-56) were greater than those of PAHs (0.12-6.3). BSAFs and BAFs of 11-79 and 4-34, respectively, were registered for OCPs in eggs of the birds and were greater than those for PAHs (0.11-1.5 and 0.02-1.3, respectively). Assuming that fish were the main prey of the birds, greater bioaccumulation of OCPs was detected for both bird species (BAFs =4.5-34), while accumulation of PAHs was only detected in Little Egret (BAF=1.3). A significant linear relationship (p<0.01) was observed between concentrations of OCPs in bird eggs and in the prey fish. The present study provides a new possibility of using OCP levels detected in prey fish to predict the extent of OCPs contamination in eggs of waterbirds including the endangered species, as a noninvasive method.

A randomised controlled trial of sublingual buprenorphine-naloxone film versus tablets in the management of opioid dependence

BACKGROUND

Buprenorphine-naloxone sublingual film was introduced in 2011 in Australia as an alternative to tablets. This study compared the two formulations on subjective dose effects and equivalence, trough plasma levels, adverse events, patient satisfaction, supervised dosing time, and impact upon treatment outcomes (substance use, psychosocial function).

METHODS

92 buprenorphine-naloxone tablet patients were recruited to this outpatient multi-site double-blind double-dummy parallel group trial. Patients were randomised to either tablets or film, without dose changes, over a 31 day period.

RESULTS

No significant group differences were observed for subjective dose effects, trough plasma buprenorphine or norbuprenorphine levels, adverse events and treatment outcomes. Buprenorphine-naloxone film took significantly less time to dissolve than tablets (173±71 versus 242±141s, p=0.007, F=7.67).

CONCLUSIONS

The study demonstrated dose equivalence and comparable clinical outcomes between the buprenorphine-naloxone film and tablet preparations, whilst showing improved dispensing times and patient ratings of satisfaction with the film.

Integration of DNA copy number alterations and transcriptional expression analysis in human gastric cancer

Background

Genomic instability with frequent DNA copy number alterations is one of the key hallmarks of carcinogenesis. The chromosomal regions with frequent DNA copy number gain and loss in human gastric cancer are still poorly defined. It remains unknown how the DNA copy number variations contributes to the changes of gene expression profiles, especially on the global level.

Principal Findings

We analyzed DNA copy number alterations in 64 human gastric cancer samples and 8 gastric cancer cell lines using bacterial artificial chromosome (BAC) arrays based comparative genomic hybridization (aCGH). Statistical analysis was applied to correlate previously published gene expression data obtained from cDNA microarrays with corresponding DNA copy number variation data to identify candidate oncogenes and tumor suppressor genes. We found that gastric cancer samples showed recurrent DNA copy number variations, including gains at 5p, 8q, 20p, 20q, and losses at 4q, 9p, 18q, 21q. The most frequent regions of amplification were 20q12 (7/72), 20q12–20q13.1 (12/72), 20q13.1–20q13.2 (11/72) and 20q13.2–20q13.3 (6/72). The most frequent deleted region was 9p21 (8/72). Correlating gene expression array data with aCGH identified 321 candidate oncogenes, which were overexpressed and showed frequent DNA copy number gains; and 12 candidate tumor suppressor genes which were down-regulated and showed frequent DNA copy number losses in human gastric cancers. Three networks of significantly expressed genes in gastric cancer samples were identified by ingenuity pathway analysis.

Conclusions

This study provides insight into DNA copy number variations and their contribution to altered gene expression profiles during human gastric cancer development. It provides novel candidate driver oncogenes or tumor suppressor genes for human gastric cancer, useful pathway maps for the future understanding of the molecular pathogenesis of this malignancy, and the construction of new therapeutic targets.

Abstract 4535: CENP-E and c-Myc expression identifies a sensitive population of gastric cancer

Centromere-associated protein E (CENP-E) is expressed during mitosis and plays an essential role in establishing and maintaining stable connections between mitotic chromosomes and the microtubules of the spindle. Previous preclinical studies have shown that inhibition of CENP-E function by small interfering RNA, blocking antibodies or small molecule inhibitors arrested cell cycle before metaphase, and could lead to cell death. In a number of cancers, CENP-E is frequently overexpressed in tumor tissues compared with their normal counterparts. In this study, we showed that CENP-E is overexpressed in about 60% of gastric cancer (intestinal and diffuse-type) tissues. In addition, c-Myc up-regulation was observed in more than 50% of the same samples. Overall, about 40% of all gastric tumor samples harbor both CENP-E and c-Myc upregulation. Using a panel of small molecule inhibitors of CENP-E, we evaluated in vitro anti-proliferation effect in a panel of gastric cancer cell lines. Our data suggested that cells with higher levels of c-Myc transcript were more sensitive to CENP-E inhibition. This preliminary study indicated that c-Myc amplification and/or over-expression could be a potential biomarker for selecting gastric cancer patients more likely to respond to CENP-E inhibition.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4535. doi:1538-7445.AM2012-4535

Role of gender disparity of circulating high-sensitivity C-reactive protein concentrations and obesity on asthma in Taiwan

BACKGROUND

Several studies have suggested that the association between obesity and asthma may be stronger in females than in males, but the reason is still unclear.

OBJECTIVE

The aim of this study was to investigate whether differences in high-sensitivity C-reactive protein (hs-CRP) levels explain why obesity is associated with asthma in females but not in males.

METHODS

This study prospectively enrolled 754 subjects ≥ 18 years old from hospital-based asthma patients and population-based controls. We measured adiposity factors [body mass index (BMI), waist circumference and waist-hip ratio], hs-CRP and total IgE levels.

RESULTS

After adjusting for potential confounding factors, we found a significant association between BMI and asthma in females with a significant interaction of gender and BMI on asthma (χ(2) =10.2, P=0.004). If hs-CRP was added to the logistic model, the interaction was attenuated but still significant (χ(2) =7.02, P=0.03). After adjusting for BMI, we did not find that circulating hs-CRP concentrations were significantly associated with asthma in males and females.

CONCLUSION

We found that BMI was associated with asthma in females, but our results do not support the suggestion that hs-CRP levels contribute significantly to the link between obesity and asthma with respect to gender disparity.

Use of nutritional health supplements and associated factors among parents with children at kindergartens in Hong Kong

OBJECTIVES. To estimate the prevalence of so-called nutritional health supplement consumption among kindergarten children; secondarily to explore potential factors associated with such consumption. DESIGN. Cross-sectional, self-administered questionnaire survey. SETTING. One kindergarten each in Hong Kong island, Kowloon, and the New Territories region. SUBJECTS. Parents who had a child studying at the three sampled kindergartens in April 2010. RESULTS. Of 951 sets of parents, 730 (77%) responded. Approximately 52% (95% confidence interval, 47-58%) of the respondents gave regular health supplements to their child. The commonest type of supplement given was cod fish oil (69%). Approximately 36% of the respondents did not know the upper limit dosage of their supplement. Parents of only 66% of regular health supplements consumers, compared to 75% of non-regular users, knew that there was an inherent risk from over-consumption (P=0.018). Parental beliefs that "It is useful/important for normal child development" (adjusted odds ratio=1.93; 95% confidence interval, 1.18-3.16; P=0.009), "It is useful/important for immune function" (1.79; 1.05-3.05; P=0.032) were associated with consumption of health such supplements. CONCLUSION. There is high rate of health supplement consumption among healthy kindergarten children in Hong Kong. There are wrong beliefs from parents that health supplements are important for normal-growing children for their normal growth and body immunity. About one-third of parents has limited knowledge on potential side-effects of overdose and do not know the limit of consumption. Education on "Less (health supplement) is more (health)" is recommended.

Indian hedgehog regulates intestinal stem cell fate through epithelial-mesenchymal interactions during development

BACKGROUND & AIMS

Intestinal stem cells (ISCs) are regulated by the mesenchymal environment via physical interaction and diffusible factors. We examined the role of Indian hedgehog (Ihh) in mesenchymal organization and the mechanisms by which perturbations in epithelial-mesenchymal interactions affect ISC fate.

METHODS

We generated mice with intestinal epithelial-specific disruption of Ihh. Gross and microscopic anatomical changes were determined using histologic, immunohistochemical, and in situ hybridization analyses. Molecular mechanisms were elucidated by expression profiling and in vitro analyses.

RESULTS

Deletion of intestinal epithelial Ihh disrupted the intestinal mesenchymal architecture, demonstrated by loss of the muscularis mucosae, deterioration of the extracellular matrix, and reductions in numbers of crypt myofibroblasts. Concurrently, the epithelial compartment had increased Wnt signaling, disturbed crypt polarity and architecture, defective enterocyte differentiation, and increased and ectopic proliferation that was accompanied by increased numbers of ISCs. Mechanistic studies revealed that Hh inhibition deregulates bone morphogenetic protein signaling, increases matrix metalloproteinase levels, and disrupts extracellular matrix proteins, fostering a proliferative environment for ISCs and progenitor cells.

CONCLUSIONS

Ihh regulates ISC self-renewal and differentiation. Intestinal epithelial Ihh signals to the mesenchymal compartment to regulate formation and proliferation of mesenchymal cells, which in turn affect epithelial proliferation and differentiation. These findings provide a basis for analyses of the role of the muscularis mucosae in ISC regulation.

Ecotoxicological study on sediments of Mai Po marshes, Hong Kong using organisms and biomarkers

Sediments from Mai Po Ramsar site, Hong Kong were in general shown to be highly toxic based on the results of four toxicity tests (Microtox solid-phase test, Daphnia mortality test, algal [Microcystis aeruginosa] growth inhibition test and ryegrass [Lolium perenne] seed germination/root elongation test). Sediment of the mudflat (which is open to Deep Bay, i.e., the pollution source) was the most toxic while sediment of gei wai 24g (an enclosed freshwater pond) was the least toxic. Results of biomarker studies (tilapia hepatic metallothionein; glutathione (GSH) and EROD activity using H4IIE rat hepatoma cell) were also concordant with those in the toxicity tests. Significant liner relationships (p<0.01) were found between GSH contents in the rat hepatoma cells and PAHs, OCPs contents in the sediment extracts. It is recommended that the present suite of bioassays is useful and is biologically relevant for future ecotoxicological studies focusing on similar wetlands.

Abstract 4909: The role of CpG island methylator phenotype 2 (CIMP2) in early onset colorectal cancer patients

CpG Island Methylator Phenotype (CIMP), characterized by methylation at various promoter sites, has been reported as a subgroup in colorectal cancer. CIMP1 is often associated with microsatellite instability (MSI) as well as BRAF mutation while CIMP negative enriched with P53 mutant. Besides, a CIMP2 classification has also been established and indicated to be associated with KRAS mutation. Most of these experiments related to CIMP were carried out on tumor samples from late onset patients with a mean or median age of at least 60. Thus it was of interest to observe any deviation of such pattern among early onset colorectal cancer population. Bisulfite conversion of the extracted DNA from 73 tumor samples with MSS status were examined via pyrosequence for their methylation status among loci MINT1, MINT2 and MINT27, the most frequently methylated sites reported in CIMP 2 phenomenon. These samples were free from MLH1 methylation and BRAF mutation to exclude conditions of CIMP1. The age group ranged from 29 to 68 years old with a mean age of 50.7 years old. Sequencing of its genomic DNA for KRas mutation was also screened as per se to previous studies. It was found that CIMP2 appeared more frequently in patients over the age of 50 (p=0.04) when compared with patients below 50 years old. Furthermore, methylation of the CIMP 2 loci examined (MINT1, MINT2 and MINT27) were most likely accompanied with the mutation of KRas in patients over 50 years old (p=0.05) while there was no observed correlation of CIMP 2 loci and KRas mutation in patient samples under 50 years of age. Since the CIMP2 phenotype is not seen in early-onset CRC samples, our data suggests that an alternative pathway, but not CIMP, may be responsible for the tumorigenesis of early-onset MSS CRC. Moreover, current studies proposed chromosomal instability may be a distinct mechanism in the pathogenesis of CRC, thus investigation would be carried on this aspect.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4909.

Risk assessment of residual DDTs in freshwater and marine fish cultivated around the Pearl River Delta, China

Six species of freshwater fish collected from 10 fishponds in Shunde and Zhongshan, China, four species of marine fishes collected from different mariculture farms [four in Hong Kong (Tung Lung Chau, Ma Wan, Cheung Chau and Kat O) and two in mainland China (Daya Bay and Shenzhen)] together with feed (both trash fish and commercial pellets) and sediment were analyzed for DDTs. Total DDTs in freshwater fish flesh decreased in the order of: carnivores [1742 microg/kg lipid weight (l.w.)] > herbivores (165 microg/kg, l.w.) > omnivores (42.5 microg/kg, l.w.), with the highest concentration detected in mandarin fish (Siniperca chuatsi) (2641 microg/kg, l.w.). For marine fish, snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides) collected in Ma Wan contained elevated levels of total DDTs (2590 and 2034 microg/kg l.w., respectively). Trash fish used in both freshwater and marine fish farms contained significantly higher levels (86.5-641 microg/kg l.w.) (p < 0.05) of DDTs than in commercial pellets, but correlations between DDT levels in fish feed and muscle were not significant. The elevated biota-sediment accumulating factor for tilapia (Tilapia mossambicus) (24.1) indicated that accumulation of DDTs from sediment to the fish was evident. It can be concluded that trash fish should not be used for fish culture in order to lower the level of residual DDTs in fish muscle.

Kinetics of toluene degradation by a nitrate-reducing bacterium isolated from a groundwater aquifer

Groundwater from a xylene-contaminated acquifer was enriched in the laboratory in the presence of toluene, xylenes, ethylbenzene, and benzene. A pure culture that degrades toluene and m-xylene under nitrate-reducing conditions was isolated. Fatty acid analysis, 16S rRNA sequencing, and morphological traits indicate that the isolate was a strain of Azoarcus tolulyticus. The kinetics of toluene degradation under nitrate-reducing conditions by this isolate was determined. Nitrate reduction does not proceed beyond nitrite. Nitrate and toluene are substrate limiting at low concentrations, whereas toluene, nitrate, and nitrite are inhibitory at high concentrations. Several inhibition models were compared to experimental data to represent inhibition by these substrates. A kinetic model for toluene and nitrate degradation as well as for cell growth and nitrite production was developed and compared to experimental data. The results of this work may find important application in the remediation of groundwater aquifers contaminated with aromatic hydrocarbons.

Association of inflammation-related and microRNA gene expression with cancer-specific mortality of colon adenocarcinoma

PURPOSE

Inflammatory genes and microRNAs have roles in colon carcinogenesis; therefore, they may provide useful biomarkers for colon cancer. This study examines the potential clinical utility of an inflammatory gene expression signature as a prognostic biomarker for colon cancer in addition to previously examined miR-21 expression.

EXPERIMENTAL DESIGN

Quantitative reverse transcriptase-PCR. was used to measure the expression of 23 inflammatory genes in colon adenocarcinomas and adjacent noncancerous tissues from 196 patients. These data were used to develop models for cancer-specific mortality on a training cohort (n = 57), and this model was tested in both a test (n = 56) and a validation (n = 83) cohort. Expression data for miR-21 were available for these patients and were compared and combined with inflammatory gene expression.

RESULTS

PRG1, IL-10, CD68, IL-23a, and IL-12a expression in noncancerous tissue, and PRG1, ANXA1, IL-23a, IL-17a, FOXP3, and HLA-DRA expression in tumor tissues were associated with poor prognosis based on Cox regression (/Z-score/ >1.5) and were used to generate the inflammatory risk score (IRS). IRS was associated with cancer-specific mortality in the training, test (P = 0.01), and validation (P = 0.02) cohorts. This association was strong for stage II cases (P = 0.002). Expression of miR-21 was associated with IL-6, IL-8, IL-10, IL-12a, and NOS2a, providing evidence that the function of this microRNA and these inflammatory genes are linked. Both IRS and miR-21 expression were independently associated with cancer-specific mortality, including stage II patients alone.

CONCLUSION

IRS and miR-21 expression are independent predictors of colon cancer prognosis and may provide a clinically useful tool to identify high-risk patients.