Methylation of microribonucleic acid Let-7b regulatory regions in endometriosis.

OBJECTIVE: To evaluate whether Let-7b regulatory regions are methylated in endometriosis and whether there are specific CpG methylation sites that can be identified as key epigenetic regulatory locations. DESIGN: Laboratory study. SETTING: Academic Medical Center. PATIENT(S): Twenty-one women with (n = 12) and without (n = 9) endometriosis. INTERVENTION(S): Laboratory investigation. In vitro assessment of Let-7b methylation. MAIN OUTCOME MEASURE(S): Four targeted regions upstream of Let-7b predicted to be the regulatory regions of this microribonucleic acid (miRNA) were amplified using bisulfite-specific polymerase chain reaction. Deoxyribonucleic acid sequences were analyzed to determine methylation status at each predicted regulatory region and CpG island. RESULT(S): Regions were chosen on the basis of percent (%) GC content and data from Ensembl/ENCODE databases, which predict locations of promoters, enhancers, CTCF, and transcription factor binding sites as well as candidate cis-regulatory elements. A region 1,161 base pairs upstream of the Let-7b coding region was significantly differentially methylated in ectopic samples compared with eutopic endometrium from patients with endometriosis. Four specific CpG islands within this region 2 were further analyzed individually, and 1 was found to be significantly methylated in endometriosis. We identified that transcription factor SP1 was predicted to bind to a sequence that contained this specific methylated CpG in endometriosis. CONCLUSION(S): We identified differential Let-7b methylation in endometriosis, demonstrating that the epigenetic nature of the disease extends to the regulation of miRNAs. Methylation of this novel Let-7b regulatory region explains the decreased levels of this miRNA in endometriosis and is distinct from the regions implicated in regulating Let-7b in cancer. Understanding of the disease-specific mechanisms leading to diminished expression may allow for better understanding of the etiology of endometriosis as well as development of new treatment options.

Effect of Low-dose and Standard-dose Aspirin on PGE2 Biosynthesis Among Individuals with Colorectal Adenomas: A Randomized Clinical Trial.

Low-dose aspirin is recommended by the U.S. Preventive Services Task Force for primary prevention of colorectal cancer in certain individuals. However, broader implementation will require improved precision prevention approaches to identify those most likely to benefit. The major urinary metabolite of PGE2, 11α-hydroxy-9,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid (PGE-M), is a biomarker for colorectal cancer risk, but it is unknown whether PGE-M is modifiable by aspirin in individuals at risk for colorectal cancer. Adults (N = 180) who recently underwent adenoma resection and did not regularly use aspirin or NSAIDs were recruited to a double-blind, placebo-controlled, randomized trial of aspirin at 81 or 325 mg/day for 8-12 weeks. The primary outcome was postintervention change in urinary PGE-M as measured by LC/MS. A total of 169 participants provided paired urine samples for analysis. Baseline PGE-M excretion was 15.9 ± 14.6 (mean ± S.D, ng/mg creatinine). Aspirin significantly reduced PGE-M excretion (-4.7 ± 14.8) compared with no decrease (0.8 ± 11.8) in the placebo group (P = 0.015; mean duration of treatment = 68.9 days). Aspirin significantly reduced PGE-M levels in participants receiving either 81 (-15%; P = 0.018) or 325 mg/day (-28%; P < 0.0001) compared with placebo. In 40% and 50% of the individuals randomized to 81 or 325 mg/day aspirin, respectively, PGE-M reduction reached a threshold expected to prevent recurrence in 10% of individuals. These results support that aspirin significantly reduces elevated levels of PGE-M in those at increased colorectal cancer risk to levels consistent with lower risk for recurrent neoplasia and underscore the potential utility of PGE-M as a precision chemoprevention biomarker. The ASPIRED trial is registered as NCT02394769.

Structure of the Mucosal and Stool Microbiome in Lynch Syndrome.

The gut microbiota has been associated with colorectal cancer (CRC), but causal alterations preceding CRC have not been elucidated. To prospectively assess microbiome changes prior to colorectal neoplasia, we investigated samples from 100 Lynch syndrome patients using 16S rRNA gene sequencing of colon biopsies, coupled with metagenomic and metatranscriptomic sequencing of feces. Colectomy and CRC history represented the largest effects on microbiome profiles. A subset of Clostridiaceae were depleted in stool corresponding with baseline adenomas, while Desulfovibrio was enriched both in stool and in mucosal biopsies. A classifier leveraging stool metatranscriptomes resulted in modest power to predict interval development of preneoplastic colonic adenoma. Predictive transcripts corresponded with a shift in flagellin contributors and oxidative metabolic microenvironment, potentially factors in local CRC pathogenesis. This suggests that the effectiveness of prospective microbiome monitoring for adenomas may be limited but supports the potential causality of these consistent, early microbial changes in colonic neoplasia.