Sirtuin 7 super-enhancer drives epigenomic reprogramming in hepatocarcinogenesis.

Hepatocellular carcinoma (HCC) is a major cancer burden worldwide with increasing incidence in many developed countries. Super-enhancers (SEs) drive gene expressions required for cell type-specificity and tumor cell identity. However, their roles in HCC remain unclear because of data scarcity from primary tumors. Herein, chromatin profiling of non-alcoholic fatty liver disease (NAFLD)-associated HCCs and matched liver tissues uncovered an average of ∼500 somatically-acquired SEs per patient. The identified SE-target genes were functionally enriched for aberrant metabolism and cancer phenotypes, especially chromatin regulators including deacetylases and Polycomb repressive complexes. Notably, all examined tumors exhibited SE activation of Sirtuin 7 (SIRT7), genome-wide promoter H3K18 deacetylation and concurrent H3K27me3, as well as tumor-suppressor gene silencing. Depletion of SIRT7 SE in hepatoma cells induced global H3K18 acetylation and reactivated key metabolic and immune regulators, leading to marked suppression of tumorigenicity in vitro and in vivo. In concordance, SIRT7 physically interacted with the methyltransferase EZH2, and they were co-expressed in primary HCCs. In summary, our integrative analysis establishes a compendium of SEs in NAFLD-associated HCCs and uncovers SIRT7-driven chromatin regulatory network as potential druggable vulnerability of this increasingly prevalent cancer.

Multi-omic analysis suggests tumor suppressor genes evolved specific promoter features to optimize cancer resistance.

Tumor suppressor genes (TSGs) exhibit distinct evolutionary features. We speculated that TSG promoters could have evolved specific features that facilitate their tumor-suppressing functions. We found that the promoter CpG dinucleotide frequencies of TSGs are significantly higher than that of non-cancer genes across vertebrate genomes, and positively correlated with gene expression across tissue types. The promoter CpG dinucleotide frequencies of all genes gradually increase with gene age, for which young TSGs have been subject to a stronger evolutionary pressure. Transcription-related features, namely chromatin accessibility, methylation and ZNF263-, SP1-, E2F4- and SP2-binding elements, are associated with gene expression. Moreover, higher promoter CpG dinucleotide frequencies and chromatin accessibility are positively associated with the ability of TSGs to resist downregulation during tumorigenesis. These results were successfully validated with independent datasets. In conclusion, TSGs evolved specific promoter features that optimized cancer resistance through achieving high expression in normal tissues and resistance to downregulation during tumorigenesis.

Targeting the polycomb repressive complex-2 related proteins with novel combinational strategies for nasopharyngeal carcinoma.

Aberrant epigenetic regulation is critically involved in the pathogenesis of nasopharyngeal carcinoma (NPC), where abnormal histone methylation can be found in polycomb repressive complex-2 (PRC2) related cancer gene loci. This study investigated some novel combinational strategies against NPC in vitro using PRC2-targeting agents as a backbone. PRC2 subunit proteins were overexpressed in over 70% of NPC tumors and enhancer of zeste homolog-2 (EZH2) expression correlated with more advanced T-stage. Basal expression of EZH2 and embryonic ectoderm development (EED) was higher in Epstein-Bar virus (EBV)+ NPC cells than EBV- cells. Treatment with an EED inhibitor (EED226) led to reduced levels of H3K27me3 with minimal inhibitory effect on NPC cell growth. The combination of an EZH2 inhibitor (EPZ-6438) and trichostatin-A (TSA) yielded the highest synergy score (12.64) in NPC cells in vitro than combinations using EED226 and agents like chemotherapy and azacitadine. Global gene expression analysis showed that EED226 predominantly affects the expression of major histocompatibility complex (MHC) class I genes and cell cycle-related genes in NPC cells. Furthermore, treatment with EED226 resulted in increased MHC-I proteins in vitro. Based on the prediction of an artificial neural network, a synergistic inhibitory effect on growth was found by combining EED226 with cyclin dependent kinase (CDK) 4/6 inhibitor (LEE011) in NPC cells. In summary, this study found that PRC2-targeting agents could exert synergistic effect on growth inhibition when combined with TSA or LEE011 in NPC cells. Since MHC-I genes alterations are found in a third of NPC tumors, the effect of EED226 on MHC-I genes expression on response to immunotherapy in NPC warrants further investigations.

"Interchangeability" of PD-L1 immunohistochemistry assays: a meta-analysis of diagnostic accuracy.

Different clones, protocol conditions, instruments, and scoring/readout methods may pose challenges in introducing different PD-L1 assays for immunotherapy. The diagnostic accuracy of using different PD-L1 assays interchangeably for various purposes is unknown. The primary objective of this meta-analysis was to address PD-L1 assay interchangeability based on assay diagnostic accuracy for established clinical uses/purposes. A systematic search of the MEDLINE database using PubMed platform was conducted using "PD-L1" as a search term for 01/01/2015 to 31/08/2018, with limitations "English" and "human". 2,515 abstracts were reviewed to select for original contributions only. 57 studies on comparison of two or more PD-L1 assays were fully reviewed. 22 publications were selected for meta-analysis. Additional data were requested from authors of 20/22 studies in order to enable the meta-analysis. Modified GRADE and QUADAS-2 criteria were used for grading published evidence and designing data abstraction templates for extraction by reviewers. PRISMA was used to guide reporting of systematic review and meta-analysis and STARD 2015 for reporting diagnostic accuracy study. CLSI EP12-A2 was used to guide test comparisons. Data were pooled using random-effects model. The main outcome measure was diagnostic accuracy of various PD-L1 assays. The 22 included studies provided 376 2×2 contingency tables for analyses. Results of our study suggest that, when the testing laboratory is not able to use an Food and Drug Administration-approved companion diagnostic(s) for PD-L1 assessment for its specific clinical purpose(s), it is better to develop a properly validated laboratory developed test for the same purpose(s) as the original PD-L1 Food and Drug Administration-approved immunohistochemistry companion diagnostic, than to replace the original PD-L1 Food and Drug Administration-approved immunohistochemistry companion diagnostic with a another PD-L1 Food and Drug Administration-approved companion diagnostic that was developed for a different purpose.

Eukaryotic elongation factor-2 kinase expression is an independent prognostic factor in colorectal cancer.

BACKGROUND: Prognostication of patients with colorectal cancer (CRC) currently relies on tumor-node-metastasis (TNM) staging but clinical outcomes of patients of the same histoclinical stage are heterogeneous. It is therefore imperative to devise novel molecular tests to stratify CRC patients. Our previous work demonstrated that eukaryotic elongation factor-2 kinase (EEF2K) is a tumor suppressor in CRC. Herein, we investigated EEF2K expression in CRC and determined its relationship with clinicopathological parameters. METHODS: Quantitative RT-PCR and Westerns blots were used to examine EEF2K expression in primary tumor and the adjacent non-tumor tissues of CRC patients (n = 20). Kaplan-Meier curves and Cox regression analysis were used to assess the association between clinical outcomes of CRC patients and EEF2K protein expression determined by immunohistochemistry on tissue microarray (n = 151). RESULTS: EEF2K was significantly downregulated at both mRNA and protein levels in tumors of CRC patients. Univariate Cox regression analysis revealed that CRC patients with high tumor grade, advanced TNM staging and low EEF2K expression were associated with worse overall survival. Multivariate analysis further demonstrated that low EEF2K expression was an independent factor for predicting poorer overall survival in CRC patients (p = 0.014; Hazard ratio = 2.951; 95% confidence interval: 1.240-7.024). The 5-year survival rate was 82.8% in the EEF2K-high-expression group versus 63.9% in the EEF2K-low-expression group (p = 0.0118). The association of overall survival with EEF2K expression in CRC patients was verified in The Cancer Genome Atlas (TCGA) cohort. CONCLUSIONS: EEF2K is downregulated in CRC and its expression can be employed as a prognostic marker for CRC patients independent of TNM staging.

WITER: a powerful method for estimation of cancer-driver genes using a weighted iterative regression modelling background mutation counts.

Genomic identification of driver mutations and genes in cancer cells are critical for precision medicine. Due to difficulty in modelling distribution of background mutation counts, existing statistical methods are often underpowered to discriminate cancer-driver genes from passenger genes. Here we propose a novel statistical approach, weighted iterative zero-truncated negative-binomial regression (WITER, http://grass.cgs.hku.hk/limx/witer or KGGSeq,http://grass.cgs.hku.hk/limx/kggseq/), to detect cancer-driver genes showing an excess of somatic mutations. By fitting the distribution of background mutation counts properly, this approach works well even in small or moderate samples. Compared to alternative methods, it detected more significant and cancer-consensus genes in most tested cancers. Applying this approach, we estimated 229 driver genes in 26 different types of cancers. In silico validation confirmed 78% of predicted genes as likely known drivers and many other genes as very likely new drivers for corresponding cancers. The technical advances of WITER enable the detection of driver genes in TCGA datasets as small as 30 subjects and rescue of more genes missed by alternative tools in moderate or small samples.

Assessment of programmed cell death ligand-1 expression by 4 diagnostic assays and its clinicopathological correlation in a large cohort of surgical resected non-small cell lung carcinoma.

Immune checkpoint blockade targeting the PD-1/PD-L1 axis has recently demonstrated efficacy and promise in cancer treatment. Appropriate biomarker selection is therefore essential for improving treatment efficacy. However, the establishment of PD-L1 assay in pathology laboratories is complicated by the presence of multiple testing platforms using different scoring systems. Here we assessed the PD-L1 expression in 713 consecutive non-small cell lung carcinomas by four commercially available PD-L1 immunohistochemical assays, namely, 22C3, 28-8, SP142 and SP263. The analytical performances of the four assays and diagnostic performances across clinically relevant cutoffs were evaluated. The prevalence of PD-L1 (22C3) expression was 21% with a ≥50% cutoff and 56% with a ≥1% cutoff. High PD-L1 expression (using a ≥50% cutoff) was significantly associated with male sex (P = 0.001), ever smoking history (P < 0.001), squamous cell carcinoma (P = 0.001), large cell carcinoma (P < 0.001), lymphoepithelioma-like carcinoma (P = 0.006), sarcomatoid carcinoma (P < 0.001), mutant KRAS (P = 0.005) and wild-type EGFR (P = 0.003). Elevated PD-L1 expression was also significantly associated with shorter survival in patients with adenocarcinoma (log-rank P = 0.026) and remained an independent prognostic factor by multivariable analysis. Among the four assays, 22C3, 28-8 and SP263 were highly concordant for tumor cell scoring. With a cutoff of ≥50% (i.e., the threshold for first-line patient selection), inter-rater agreement was high among the three assays with percentage agreement >97%. In conclusion, three PD-L1 assays showed good analytical performance and a high agreement with each other, but not all cases were correctly classified using the same clinical cutoff. Further studies comparing the predictive value of these assays are required to address the interchangeability of these assays for clinical use.

Genomic analysis of liver cancer unveils novel driver genes and distinct prognostic features.

Objective: Hepatocellular carcinoma (HCC) is a highly heterogeneous disease with a dismal prognosis. However, driver genes and prognostic markers in HCC remain to be identified. It is hoped that in-depth analysis of HCC genomes in relation to available clinicopathological information will give rise to novel molecular prognostic markers. Methods: We collected genomic data of 1,061 HCC patients from previous studies, and performed integrative analysis to identify significantly mutated genes and molecular prognosticators. We employed three MutSig algorithms (MutSigCV, MutSigCL and MutSigFN) to identify significantly mutated genes. The GISTIC2 algorithm was used to delineate focally amplified and deleted genomic regions. Nonnegative matrix factorization (NMF) was utilized to decipher mutational signatures. Kaplan-Meier survival and Cox regression analyses were used to associate gene mutation and copy number alteration with survival outcome. Logistic regression model was applied to test association between gene mutation and mutational signatures. Results: We discovered 11 novel driver genes, including RNF213, VAV3 and TNRC6B, with mutational prevalence ranging from 1% to 3%. Seven mutational signatures were also identified in HCC, some of which were associated with mutations of classical driver genes (e.g., TP53, TERT) as well as alcohol consumption. Focal amplifications of TERT and other druggable targets, including AURKA, were also revealed. Targeting AURKA by a small-molecule inhibitor potently induced apoptosis in HCC cells. We further demonstrated that HCC patients with TERT amplification displayed shortened overall survival independent of other clinicopathological parameters. In conclusion, our study identified novel cancer driver genes and prognostic markers in HCC, reiterating the translational importance of omics data in the precision medicine era.

Combinatorial epigenetic deregulation by Helicobacter pylori and Epstein-Barr virus infections in gastric tumourigenesis.

Epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodelling and microRNAs, convert environmental signals to transcriptional outputs but are commonly hijacked by pathogenic microorganisms. Recent advances in cancer epigenomics have shed new light on the importance of epigenetic deregulation in Helicobacter pylori- and Epstein-Barr virus (EBV)-driven gastric tumourigenesis. Moreover, it is becoming apparent that epigenetic mechanisms interact through crosstalk and feedback loops, which modify global gene expression patterns. The SWI/SNF remodelling complexes are commonly involved in gastric cancers associated with H. pylori or EBV through different mechanisms, including microRNA-mediated deregulation and genetic mutations. While H. pylori causes epigenetic silencing of tumour-suppressor genes to deregulate cellular pathways, EBV-positive tumours exhibit a widespread and distinctive DNA hypermethylation profile. Given the early successes of epigenetic drugs in haematological malignancies, further studies are mandated to enrich and translate our understanding of combinatorial epigenetic deregulation in gastric cancers into interventional strategies in the clinic. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

MET Amplification and Exon 14 Splice Site Mutation Define Unique Molecular Subgroups of Non-Small Cell Lung Carcinoma with Poor Prognosis.

PURPOSE: Activation of MET oncogene as the result of amplification or activation mutation represents an emerging molecular target for cancer treatment. We comprehensively studied MET alterations and the clinicopathologic correlations in a large cohort of treatment-naïve non-small cell lung carcinoma (NSCLC). EXPERIMENTAL DESIGN: Six hundred eighty-seven NSCLCs were tested for MET exon 14 splicing site mutation (METΔ14), DNA copy number alterations, and protein expression by Sanger sequencing, FISH, and IHC, respectively. RESULTS: METΔ14 mutation was detected in 2.62% (18/687) of NSCLC. The mutation rates were 2.6% in adenocarcinoma, 4.8% in adenosquamous carcinoma, and 31.8% in sarcomatoid carcinoma. METΔ14 mutation was not detected in squamous cell carcinoma, large cell carcinoma, and lymphoepithelioma-like carcinoma but significantly enriched in sarcomatoid carcinoma (P < 0.001). METΔ14 occurred mutually exclusively with known driver mutations but tended to coexist with MET amplification or copy number gain (P < 0.001). Low-level MET amplification and polysomy might occur in the background of EGFR or KRAS mutation whereas high-level amplification (MET/CEP7 ratio ≥5) was mutually exclusive to the major driver genes except METΔ14. Oncogenic METΔ14 mutation and/or high-level amplification occurred in a total of 3.3% (23/687) of NSCLC and associated with higher MET protein expression. METΔ14 occurred more frequently in older patients whereas amplification was more common in ever-smokers. Both METΔ14 and high-level amplification were independent prognostic factors that predicted poorer survival by multivariable analysis. CONCLUSIONS: The high incidence of METΔ14 mutation in sarcomatoid carcinoma suggested that MET inhibition might benefit this specific subgroup of patients. Clin Cancer Res; 22(12); 3048-56. ©2016 AACRSee related commentary by Drilon, p. 2832.

Histone Deacetylase HDAC8 Promotes Insulin Resistance and ß-Catenin Activation in NAFLD-Associated Hepatocellular Carcinoma.

The growing epidemic of obesity, which causes nonalcoholic fatty liver disease (NAFLD) and the more severe phenotype nonalcoholic steatohepatitis (NASH), has paralleled the increasing incidence of hepatocellular carcinoma (HCC). Accumulating evidence demonstrates that overnutrition and metabolic pathways can trigger modifications of DNA and histones via deregulation of chromatin modifiers, resulting in aberrant transcriptional activity. However, the epigenetic regulation of HCC development in NAFLD remains obscure. Here, we uncover key epigenetic regulators using both dietary and genetic obesity-promoted HCC models through quantitative expression profiling and characterize the oncogenic activities of histone deacetylase HDAC8 in NAFLD-associated hepatocarcinogenesis. HDAC8 is directly upregulated by the lipogenic transcription factor SREBP-1 where they are coexpressed in dietary obesity models of NASH and HCC. Lentiviral-mediated HDAC8 attenuation in vivo reversed insulin resistance and reduced NAFLD-associated tumorigenicity. HDAC8 modulation by genetic and pharmacologic approaches inhibited p53/p21-mediated apoptosis and G2-M phase cell-cycle arrest and stimulated ß-catenin-dependent cell proliferation. Mechanistically, HDAC8 physically interacted with the chromatin modifier EZH2 to concordantly repress Wnt antagonists via histone H4 deacetylation and H3 lysine 27 trimethylation. In human NAFLD-associated HCC, levels of SREBP-1, HDAC8, EZH2, H4 deacetylation, H3K27me3, and active ß-catenin were all correlated positively in tumors compared with nontumor tissues. Overall, our findings show how HDAC8 drives NAFLD-associated hepatocarcinogenesis, offering a novel epigenetic target to prevent or treat HCC in obese patients.

Profiling of Oncogenic Driver Events in Lung Adenocarcinoma Revealed MET Mutation as Independent Prognostic Factor.

INTRODUCTION: Oncogenic driver mutations activating receptor tyrosine kinase pathways are promising predictive markers for targeted treatment. We investigated the mutation profile of an updated driver events list on receptor tyrosine kinase/RAS/PI3K axis and the clinicopathologic implications in a cohort of never-smoker predominated Chinese lung adenocarcinoma. METHODS: We tested 154 lung adenocarcinomas and adenosquamous carcinomas for EGFR, KRAS, HER2, BRAF, PIK3CA, MET, NRAS, MAP2K1, and RIT1 mutations by polymerase chain reaction-direct sequencing. MET amplification and ALK and ROS1 translocations were assessed by fluorescent in situ hybridizations. MET and thyroid transcription factor-1 protein expressions were investigated by immunohistochemistry. RESULTS: Seventy percent of lung adenocarcinomas carried actionable driver events. Alterations on EGFR (43%), KRAS (11.4%), ALK (6%), and MET (5.4%) were frequently found. ROS1 translocation and mutations involving BRAF, HER2, NRAS, and PIK3CA were also detected. No mutation was observed in RIT1 and MAP2K1. Patients with EGFR mutations had a favorable prognosis, whereas those with MET mutations had poorer overall survival. Multivariate analysis further demonstrated that MET mutation was an independent prognostic factor. Although MET protein expression was detected in 65% of lung adenocarcinoma, only 10% of the MET-immunohistochemistry positive tumors harbor MET DNA alterations that drove protein overexpression. Appropriate predictive biomarker is essential for selecting patients who might benefit from specific targeted therapy. CONCLUSION: Actionable driver events can be detected in two thirds of lung adenocarcinoma. MET DNA alterations define a subset of patients with aggressive diseases that might potentially benefit from anti-MET targeted therapy. High negative predictive values of thyroid transcription factor-1 and MET expression suggest potential roles as surrogate markers for EGFR and/or MET mutations.

Phase I/II study of temsirolimus for patients with unresectable Hepatocellular Carcinoma (HCC)- a correlative study to explore potential biomarkers for response.

BACKGROUND: The oncogenic PI3K/Akt/mTOR pathway is frequently activated in HCC. Data on the mTOR inhibitor, temsirolimus, is limited in HCC patients with concomitant chronic liver disease. The objectives of this study were: (1) In phase I, to determine DLTs and MTD of temsirolimus in HCC patients with chronic liver disease; (2) In phase II, to assess activity of temsirolimus in HCC, and (3) to explore potential biomarkers for response. METHODS: Major eligibility criteria included histologically confirmed advanced HCC and adequate organ function. In Phase I part of the study, temsirolimus was given weekly in 3-weekly cycle; dose levels were 20 mg (level 1), 25 mg (level 2) and 30 mg (level 3). The MTD was used in the subsequent phase II part; the primary endpoint was PFS and secondary endpoints were response and OS. In addition, exploratory analysis was conducted on pre-treatment tumour tissues to determine stathmin, pS6, pMTOR or p-AKT expressions as potential biomarkers for response. Overall survival and PFS were calculated using the Kaplan-Meier method. Reassessment CT scans were done every 6 weeks. All adverse events were reported using CTCAE v3. RESULTS: The Phase I part consisted of 19 patients, 2 of 6 patients at level 3 experienced DLT; dose level 2 was determined to be the MTD. The phase II part consisted of 36 patients. Amongst 35 assessable patients, there were 1 PR, 20 SD and 14 PD. Overall, the median PFS was 2.83 months (95% C.I. 1.63-5.24). The median OS was 8.89 months (95% C.I. 5.89-13.30). Grade ≥ 3 that occurred in > 10% of patients included thrombocytopenia (4) and hyponatraemia (4). Exploratory analysis revealed that disease stabilization (defined as CR + PR + SD > 12 weeks) in tumours having high and low pMTOR H-scores to be 70% and 29% respectively (OR 5.667, 95% CI 1.129-28.454, p = 0.035). CONCLUSIONS: In HCC patients with chronic liver disease, the MTD of temsirolimus was 25 mg weekly in a 3-week cycle. The targeted PFS endpoint was not reached. However, further studies to identify appropriate patient subgroup are warranted. TRIAL REGISTRATION: This study has been registered in ClinicalTrials.gov (Id: NCT00321594) on 1 December 2010.

Novel recurrently mutated genes and a prognostic mutation signature in colorectal cancer.

BACKGROUND: Characterisation of colorectal cancer (CRC) genomes by next-generation sequencing has led to the discovery of novel recurrently mutated genes. Nevertheless, genomic data has not yet been used for CRC prognostication. OBJECTIVE: To identify recurrent somatic mutations with prognostic significance in patients with CRC. METHOD: Exome sequencing was performed to identify somatic mutations in tumour tissues of 22 patients with CRC, followed by validation of 187 recurrent and pathway-related genes using targeted capture sequencing in additional 160 cases. RESULTS: Seven significantly mutated genes, including four reported (APC, TP53, KRAS and SMAD4) and three novel recurrently mutated genes (CDH10, FAT4 and DOCK2), exhibited high mutation prevalence (6-14% for novel cancer genes) and higher-than-expected number of non-silent mutations in our CRC cohort. For prognostication, a five-gene-signature (CDH10, COL6A3, SMAD4, TMEM132D, VCAN) was devised, in which mutation(s) in one or more of these genes was significantly associated with better overall survival independent of tumor-node-metastasis (TNM) staging. The median survival time was 80.4 months in the mutant group versus 42.4 months in the wild type group (p=0.0051). The prognostic significance of this signature was successfully verified using the data set from the Cancer Genome Atlas study. CONCLUSIONS: The application of next-generation sequencing has led to the identification of three novel significantly mutated genes in CRC and a mutation signature that predicts survival outcomes for stratifying patients with CRC independent of TNM staging.

Epigenetic silencing of miR-490-3p reactivates the chromatin remodeler SMARCD1 to promote Helicobacter pylori-induced gastric carcinogenesis.

Chromatin remodeling has emerged as a hallmark of gastric cancer, but the regulation of chromatin regulators other than genetic change is unknown. Helicobacter pylori causes epigenetic dysregulation to promote gastric carcinogenesis, but the roles and functions of microRNAs (miRNA) in this multistage cascade are not fully explored. In this study, miRNA expression in preneoplastic and neoplastic lesions in murine stomachs induced by H. pylori and N-methyl-N-nitrosourea (MNU) was profiled by miRNA expression array. miR-490-3p exhibited progressive downregulation in gastritis, intestinal metaplasia, and adenocarcinoma during H. pylori and MNU-induced gastric carcinogenesis. Significant downregulation of miR-490-3p was confirmed in human gastric cancer tissues in which its regulatory region was found to be hypermethylated. miR-490-3p exerted growth- and metastasis-suppressive effects on gastric cancer cells through directly targeting SMARCD1, a SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeling complex subunit. Knockdown of SMARCD1 significantly attenuated the protumorigenic effects of miR-490-3p inhibitor, whereas enforced expression of SMARCD1 promoted in vitro and in vivo oncogenic phenotypes of gastric cancer cells. SMARCD1 was markedly upregulated in gastric cancer in which its high expression was associated with shortened patients' survival independent of TNM staging. In conclusion, hypermethylation-mediated silencing of miR-490-3p reactivates SMARCD1 to confer malignant phenotypes, mechanistically linking H. pylori, chromatin remodeling, and gastric carcinogenesis.

Intermittent versus continuous erlotinib with concomitant modified "XELOX" (q3W) in first-line treatment of metastatic colorectal cancer: correlation with serum amphiregulin and transforming growth factor alpha.

BACKGROUND: This study evaluated the activity of 2 schedules of erlotinib in combination with chemotherapy, and the prognostic significance of serum amphiregulin (AREG) and transforming growth factor alpha (TGFa) in metastatic colorectal cancer. METHODS: A total of 60 untreated patients were randomized to a "continuous" (CON; erlotinib 100 mg daily) or an "intermittent" (INT; erlotinib 150 mg on alternate day on day 2 to 14, then 150 mg daily on days 15 to 21) schedule of erlotinib with a modified XELOX (capecitabine plus oxaliplatin) regimen. Serum levels of AREG and TGFa were determined serially. RESULTS: Baseline characteristics were similar between the 2 arms. Of the 58 patients evaluated for response, there was a nonsignificant trend toward a slightly higher overall response rate in the INT arm (66.7%) versus the CON arm (56.7%). At a median follow-up of 2.8 years, the median overall survival was 18.8 months (95% confidence interval = 11.3-22.9 months) and 20.7 months (95% confidence interval = 12.5-31 months, P = .19) for the CON and INT arm, respectively. KRAS mutation did not predict drug response. The 2 arms did not differ significantly in toxicity. Baseline serum TGFa was an independent predictor of progression-free survival, whereas a drop in serum TGFa and AREG levels following 3 to 4 cycles of treatment were associated with shorter progression-free survival and overall survival, respectively. CONCLUSIONS: The intermittent erlotinib schedule was associated with a higher response rate, although this is not statistically significant. Serum TGFa and AREG levels have prognostic significance in erlotinib-treated patients with colorectal cancer, and further studies are warranted.

Genome-wide association and sequencing studies on colorectal cancer.

Colorectal cancer is a leading cause of morbidity and mortality worldwide. Understanding its genetic mechanisms is key to improving risk prediction, prognostication and treatment. Results from genome-wide association studies have engendered a growing list of colorectal cancer susceptibility genes whereas the application of genome-wide mutational analysis has enabled the depiction of mutational landscape of colorectal cancer at high resolution. The development of novel technologies, such as metagenomic and single-cell sequencing, is expected to have positive impact on future genetic studies. However, challenges remain to address the changing epidemiology of colorectal cancer, issues on genetic testing, and clinical utilization of genomic data.

Dysregulation and crosstalk of cellular signaling pathways in colon carcinogenesis.

Multiple intracellular signaling pathways, such as Wnt/ß-catenin signaling, epidermal growth factor receptor/Ras signaling, and p53 signaling are frequently dysregulated in colorectal cancer. Recent evidence also points to the involvement of signaling pathways in the developmental process, including Notch signaling, Hedgehog signaling, and Hippo signaling. Dysregulation of these signaling pathways contribute to the acquisition of malignant phenotypes, including unchecked cell cycle progression, evasion of apoptosis, induction of genetic instability, and enhanced invasiveness and metastasis. Understanding their relative importance and crosstalk will provide a rational basis for anticancer drug development.

Helicobacter pylori causes epigenetic dysregulation of FOXD3 to promote gastric carcinogenesis.

BACKGROUND & AIMS: Deregulation of forkhead box (Fox) proteins, an evolutionarily conserved family of transcriptional regulators, leads to tumorigenesis. Little is known about their regulation or functions in the pathogenesis of gastric cancer. Promoter hypermethylation occurs during Helicobacter pylori-induced gastritis. We investigated whether the deregulated genes contribute to gastric tumorigenesis. METHODS: We used integrative genome-wide scans to identify concomitant hypermethylated genes in mice infected with H pylori and human gastric cancer samples. We also analyzed epigenetic gene silencing in gastric tissues from patients with H pylori infection and gastritis, intestinal metaplasia, gastric tumors, or without disease (controls). Target genes were identified by chromatin immunoprecipitation microarrays and expression and luciferase reporter analyses. RESULTS: Methylation profile analyses identified the promoter of FOXD3 as the only genomic region with increased methylation in mice and humans during progression of H pylori-associated gastric tumors. FOXD3 methylation also correlated with shorter survival times of patients with gastric cancer. Genome demethylation reactivated FOXD3 expression in gastric cancer cell lines. Transgenic overexpression of FOXD3 significantly inhibited gastric cancer cell proliferation and invasion, and reduced growth of xenograft tumors in mice, at least partially, by promoting tumor cell apoptosis. FOXD3 bound directly to the promoters of, and activated transcription of, genes encoding the cell death regulators CYFIP2 and RARB. Levels of FOXD3, CYFIP2, and RARB messenger RNAs were reduced in human gastric tumor samples, compared with control tissues. CONCLUSIONS: FOXD3-mediated transcriptional control of tumor suppressors is deregulated by H pylori infection-induced hypermethylation; this could perturb the balance between cell death and survival. These findings identify a pathway by which epigenetic changes affect gastric tumor suppression.