Lisa A. Boardman

Frequency and Spectrum of Cancers in the Peutz-Jeghers Syndrome

Background: Although an increased cancer risk in Peutz-Jeghers syndrome is established, data on the spectrum of tumors associated with the disease and the influence of germ-line STK11/LKB1 (serine/threonine kinase) mutation status are limited. Experimental Design: We analyzed the incidence of cancer in 419 individuals with Peutz-Jeghers syndrome, and 297 had documented STK11/LKB1 mutations. Results: Ninety-six cancers were found among individuals with Peutz-Jeghers syndrome. The risk for developing cancer at ages 20, 30, 40, 50, 60, and 70 years was 2%, 5%, 17%, 31%, 60%, and 85%, respectively. The most common cancers represented in this analysis were gastrointestinal in origin, gastroesophageal, small bowel, colorectal, and pancreatic, and the risk for these cancers at ages 30, 40, 50, and 60 years was 1%, 9%, 15%, and 33%, respectively. In women with Peutz-Jeghers syndrome, the risk of breast cancer was substantially increased, being 8% and 31% at ages 40 and 60 years, respectively. Kaplan-Meier analysis showed that cancer risks were similar in Peutz-Jeghers syndrome patients with identified STK11/LKB1 mutations and those with no detectable mutation (log-rank test of difference χ2 = 0.62; 1 df; P = 0.43). Furthermore, the type or site of STK11/LKB1 mutation did not significantly influence cancer risk. Conclusions: The results from our study provide quantitative information on the spectrum of cancers and risks of specific cancer types associated with Peutz-Jeghers syndrome.

Characterization of human plasma-derived exosomal RNAs by deep sequencing

BackgroundExosomes, endosome-derived membrane microvesicles, contain specific RNA transcripts that are thought to be involved in cell-cell communication. These RNA transcripts have great potential as disease biomarkers. To characterize exosomal RNA profiles systemically, we performed RNA sequencing analysis using three human plasma samples and evaluated the efficacies of small RNA library preparation protocols from three manufacturers. In all we evaluated 14 libraries (7 replicates).ResultsFrom the 14 size-selected sequencing libraries, we obtained a total of 101.8 million raw single-end reads, an average of about 7.27 million reads per library. Sequence analysis showed that there was a diverse collection of the exosomal RNA species among which microRNAs (miRNAs) were the most abundant, making up over 42.32% of all raw reads and 76.20% of all mappable reads. At the current read depth, 593 miRNAs were detectable. The five most common miRNAs (miR-99a-5p, miR-128, miR-124-3p, miR-22-3p, and miR-99b-5p) collectively accounted for 48.99% of all mappable miRNA sequences. MiRNA target gene enrichment analysis suggested that the highly abundant miRNAs may play an important role in biological functions such as protein phosphorylation, RNA splicing, chromosomal abnormality, and angiogenesis. From the unknown RNA sequences, we predicted 185 potential miRNA candidates. Furthermore, we detected significant fractions of other RNA species including ribosomal RNA (9.16% of all mappable counts), long non-coding RNA (3.36%), piwi-interacting RNA (1.31%), transfer RNA (1.24%), small nuclear RNA (0.18%), and small nucleolar RNA (0.01%); fragments of coding sequence (1.36%), 5′ untranslated region (0.21%), and 3′ untranslated region (0.54%) were also present. In addition to the RNA composition of the libraries, we found that the three tested commercial kits generated a sufficient number of DNA fragments for sequencing but each had significant bias toward capturing specific RNAs.ConclusionsThis study demonstrated that a wide variety of RNA species are embedded in the circulating vesicles. To our knowledge, this is the first report that applied deep sequencing to discover and characterize profiles of plasma-derived exosomal RNAs. Further characterization of these extracellular RNAs in diverse human populations will provide reference profiles and open new doors for the development of blood-based biomarkers for human diseases.

Human colon cancer profiles show differential microRNA expression depending on mismatch repair status and are characteristic of undifferentiated proliferative states.

BackgroundColon cancer arises from the accumulation of multiple genetic and epigenetic alterations to normal colonic tissue. microRNAs (miRNAs) are small, non-coding regulatory RNAs that post-transcriptionally regulate gene expression. Differential miRNA expression in cancer versus normal tissue is a common event and may be pivotal for tumor onset and progression.MethodsTo identify miRNAs that are differentially expressed in tumors and tumor subtypes, we carried out highly sensitive expression profiling of 735 miRNAs on samples obtained from a statistically powerful set of tumors (n = 80) and normal colon tissue (n = 28) and validated a subset of this data by qRT-PCR.ResultsTumor specimens showed highly significant and large fold change differential expression of the levels of 39 miRNAs including miR-135b, miR-96, miR-182, miR-183, miR-1, and miR-133a, relative to normal colon tissue. Significant differences were also seen in 6 miRNAs including miR-31 and miR-592, in the direct comparison of tumors that were deficient or proficient for mismatch repair. Examination of the genomic regions containing differentially expressed miRNAs revealed that they were also differentially methylated in colon cancer at a far greater rate than would be expected by chance. A network of interactions between these miRNAs and genes associated with colon cancer provided evidence for the role of these miRNAs as oncogenes by attenuation of tumor suppressor genes.ConclusionColon tumors show differential expression of miRNAs depending on mismatch repair status. miRNA expression in colon tumors has an epigenetic component and altered expression that may reflect a reversion to regulatory programs characteristic of undifferentiated proliferative developmental states.

Mutations in DNMT1 cause hereditary sensory neuropathy with dementia and hearing loss

DNA methyltransferase 1 (DNMT1) is crucial for maintenance of methylation, gene regulation and chromatin stability. DNA mismatch repair, cell cycle regulation in post-mitotic neurons and neurogenesis are influenced by DNA methylation. Here we show that mutations in DNMT1 cause both central and peripheral neurodegeneration in one form of hereditary sensory and autonomic neuropathy with dementia and hearing loss. Exome sequencing led to the identification of DNMT1 mutation c.1484A>G (p.Tyr495Cys) in two American kindreds and one Japanese kindred and a triple nucleotide change, c.1470–1472TCC>ATA (p.Asp490Glu–Pro491Tyr), in one European kindred. All mutations are within the targeting-sequence domain of DNMT1. These mutations cause premature degradation of mutant proteins, reduced methyltransferase activity and impaired heterochromatin binding during the G2 cell cycle phase leading to global hypomethylation and site-specific hypermethylation. Our study shows that DNMT1 mutations cause the aberrant methylation implicated in complex pathogenesis. The discovered DNMT1 mutations provide a new framework for the study of neurodegenerative diseases.

A Randomized, Double-Blinded, Placebo-Controlled Multicenter Trial of Etanercept in the Treatment of Alcoholic Hepatitis

BACKGROUND & AIMS Alcoholic hepatitis is a cause of major morbidity and mortality that lacks effective therapies. Both experimental and clinical evidence indicate that the multifunctional cytokine tumor necrosis factor-alpha (TNF-alpha) contributes to pathogenesis and clinical sequelae of alcoholic hepatitis. A pilot study demonstrated that the TNF-alpha-neutralizing molecule etanercept could be an effective treatment for patients with alcoholic hepatitis. METHODS Forty-eight patients with moderate to severe alcoholic hepatitis (Model for End-Stage Liver Disease score > or = 15) were enrolled and randomized to groups that were given up to 6 subcutaneous injections of either etanercept or placebo for 3 weeks. Primary study end points included mortality at 1- and 6-month time points. RESULTS There were no significant baseline differences between the placebo and etanercept groups in demographics or disease severity parameters including age, gender, and Model for End-Stage Liver Disease score. The 1-month mortality rates of patients receiving placebo and etanercept were similar on an intention-to-treat basis (22.7% vs 36.4%, respectively; OR, 1.8; 95% CI, 0.5-6.5). The 6-month mortality rate was significantly higher in the etanercept group compared with the placebo group (57.7% vs 22.7%, respectively; OR, 4.6; 95% CI, 1.3-16.4; P = .017). Rates of infectious serious adverse events were significantly higher in the etanercept group compared with the placebo group (34.6% vs 9.1%, respectively, P = .04). CONCLUSIONS In patients with moderate to severe alcoholic hepatitis, etanercept was associated with a significantly higher mortality rate after 6 months, indicating that etanercept is not effective for the treatment of patients with alcoholic hepatitis.

Exosomal miR-1290 and miR-375 as Prognostic Markers in Castration-resistant Prostate Cancer

BACKGROUND Extracellular microRNAs (miRNAs) embedded in circulating exosomes may serves as prognostic biomarkers in cancer. OBJECTIVE To identify and evaluate plasma exosomal miRNAs for prognosis in castration-resistant prostate cancer (CRPC). DESIGN, SETTING, AND PARTICIPANTS RNA sequencing was performed to identify candidate exosomal miRNAs associated with overall survival in a screening cohort of 23 CRPC patients. Candidate miRNAs were further evaluated for prognosis using quantitative real-time polymerase chain reaction in a follow-up cohort of 100 CRPC patients. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Cox regression and Kaplan-Meier survival analyses were used to evaluate survival association using candidate miRNAs along with clinical prognostic factors. RESULTS AND LIMITATIONS RNA sequencing in screening cohort generated approximately 6.80 million mappable reads per patient. Of those with normalized read counts ≥ 5, 43% were mapped to miRNAs for a total of 375 known and 57 novel miRNAs. Cox regression analysis identified an association of miR-1290, -1246, and -375 with overall survival (false discover rate < 0.05). Of those, higher levels of miR-1290 and -375 were significantly associated with poor overall survival (p < 0.004) in the follow-up cohort. Incorporation of miR-1290/-375 into putative clinical prognostic factors-based models in CRPC stage significantly improved predictive performance with a time-dependent area under the curve increase from 0.66 to 0.73 (p = 6.57 × 10(-6)). CONCLUSIONS Plasma exosomal miR-1290 and miR-375 are promising prognostic biomarkers for CRPC patients. Prospective validation is needed for further evaluation of these candidate miRNAs. PATIENT SUMMARY In this study, we evaluated whether small RNAs circulating in blood could be used to predict clinical outcomes in late-stage prostate cancer patients. We identified two blood-based small RNAs whose levels showed significant association with survival. Our results warrant further investigation because the noninvasive blood-based test has great potential in the management of late-stage prostate cancer.

Genetic heterogeneity in Peutz-Jeghers syndrome

LKB1, the human gene encoding a serine threonine kinase, was recently identified as a susceptibility gene for Peutz‐Jeghers syndrome (PJS), a disease characterized by the constellation of intestinal hamartomata, oral mucocutaneous hyperpigmentation, and an increased risk for gastrointestinal as well as extraintestinal malignancies. To date, the majority of individuals with PJS have been found to have genetic alterations in LKB1, most of which result in protein truncation. Additionally, linkage analyses have suggested a modicum of genetic heterogeneity, with the majority of PJS families showing linkage to the LKB1 locus. In this study, we evaluated five kindreds with greater than two affected family members, five PJS probands with only one other affected family member, as well as 23 individuals with sporadic PJS for mutations within the LKB1 gene. Conformation sensitive gel electrophoresis was utilized for the initial screen, followed by direct sequence analysis for characterization. Long‐range PCR was used for the detection of larger genetic insertions or deletions. Mutation analysis revealed genetic alterations in LKB1 in two probands who had a family history of PJS. LKB1 mutations were detected in only four of the remaining 23 cases of sporadic PJS. These data suggest the presence of significant genetic heterogeneity for PJS and the involvement of other loci in this syndrome. Hum Mutat 16:23–30, 2000.

miRNA Expression in Colon Polyps Provides Evidence for a Multihit Model of Colon Cancer

Changes in miRNA expression are a common feature in colon cancer. Those changes occurring in the transition from normal to adenoma and from adenoma to carcinoma, however, have not been well defined. Additionally, miRNA changes among tumor subgroups of colon cancer have also not been adequately evaluated. In this study, we examined the global miRNA expression in 315 samples that included 52 normal colonic mucosa, 41 tubulovillous adenomas, 158 adenocarcinomas with proficient DNA mismatch repair (pMMR) selected for stage and age of onset, and 64 adenocarcinomas with defective DNA mismatch repair (dMMR) selected for sporadic (n = 53) and inherited colon cancer (n = 11). Sporadic dMMR tumors all had MLH1 inactivation due to promoter hypermethylation. Unsupervised PCA and cluster analysis demonstrated that normal colon tissue, adenomas, pMMR carcinomas and dMMR carcinomas were all clearly discernable. The majority of miRNAs that were differentially expressed between normal and polyp were also differentially expressed with a similar magnitude in the comparison of normal to both the pMMR and dMMR tumor groups, suggesting a stepwise progression for transformation from normal colon to carcinoma. Among the miRNAs demonstrating the largest fold up- or down-regulated changes (≥4), four novel (miR-31, miR-1, miR-9 and miR-99a) and two previously reported (miR-137 and miR-135b) miRNAs were identified in the normal/adenoma comparison. All but one of these (miR-99a) demonstrated similar expression differences in the two normal/carcinoma comparisons, suggesting that these early tumor changes are important in both the pMMR- and dMMR-derived cancers. The comparison between pMMR and dMMR tumors identified four miRNAs (miR-31, miR-552, miR-592 and miR-224) with statistically significant expression differences (≥2-fold change).

Polymorphisms in DNA Repair Genes, Smoking, and Pancreatic Adenocarcinoma Risk

Base excision repair and nucleotide excision repair are vital responses to multiple types of DNA damage, including damage from tobacco exposure. Single-nucleotide polymorphisms (SNP) in these pathways may affect DNA repair capacity and therefore influence risk for cancer development. We performed a clinic-based, case-control study comprising 481 consecutive patients with confirmed pancreatic adenocarcinoma and 625 healthy controls. Allele and genotype frequencies for 16 SNPs in DNA repair genes ERCC1, XPD/ERCC2, XPC, XPF/ERCC4, OGG1, and XRCC1 were compared after adjusting for age, sex, and smoking history. Subgroup analysis by sex and smoking history was performed. Carriers of one or two XPF/ERCC4 minor alleles at R415Q had decreased risk of pancreatic adenocarcinoma compared with those who had two major alleles [odds ratio (OR), 0.59; 95% confidence interval (95% CI), 0.40-0.85]. Heavy smokers (>40 pack-years) had increased risk for cancer if they were carriers of at least one minor allele for XPD/ERCC2 at D312N (OR, 2.78; 95% CI, 1.28-6.04) or D711D (OR, 2.19; 95% CI, 1.01-4.73). No other significant differences in risk were identified. Minor alleles in DNA repair genes XPF/ERCC4 and XPD/ERCC2 were associated with altered risk for pancreatic cancer.

The Stool DNA Test Is More Accurate Than the Plasma Septin 9 Test in Detecting Colorectal Neoplasia

BACKGROUND & AIMS Several noninvasive tests have been developed for colorectal cancer (CRC) screening. We compared the sensitivities of a multimarker test for stool DNA (sDNA) and a plasma test for methylated septin 9 (SEPT9) in identifying patients with large adenomas or CRC. METHODS We analyzed paired stool and plasma samples from 30 patients with CRC and 22 with large adenomas from Mayo Clinic archives. Stool (n = 46) and plasma (n = 49) samples from age- and sex-matched patients with normal colonoscopy results were used as controls. The sDNA test is an assay for methylated BMP3, NDRG4, vimentin, and TFPI2; mutant KRAS; the β-actin gene, and quantity of hemoglobin (by the porphyrin method). It was performed blindly at Exact Sciences (Madison, Wisconsin); the test for SEPT9 was performed at ARUP Laboratories (Salt Lake City, Utah). Results were considered positive based on the manufacturers specificity cutoff values of 90% and 89%, respectively. RESULTS The sDNA test detected adenomas (median, 2 cm; range, 1-5 cm) with 82% sensitivity (95% confidence interval [CI], 60%-95%); SEPT9 had 14% sensitivity (95% CI, 3%-35%; P = .0001). The sDNA test identified patients with CRC with 87% sensitivity (95% CI, 69%-96%); SEPT9 had 60% sensitivity (95% CI, 41%-77%; P = .046). The sDNA test identified patients with stage I-III CRC with 91% sensitivity (95% CI, 71%-99%); SEPT9 had 50% sensitivity (95% CI, 28%-72%; P = .013); for stage IV CRC, sensitivity values were 75% (95% CI, 35%-97%) and 88% (95% CI, 47%-100%), respectively (P = .56). False positive rates were 7% for the sDNA test and 27% for SEPT9. CONCLUSIONS Based on analyses of paired samples, the sDNA test detects nonmetastatic CRC and large adenomas with significantly greater levels of sensitivity than the SEPT9 test. These findings might be used to modify approaches for CRC prevention and early detection.