Exosomal microRNAs (miRNAs) have been attracting major interest as potential diagnostic biomarkers of cancer. The aim of this study was to characterize the miRNA profiles of serum exosomes and to identify those that are altered in colorectal cancer (CRC). To evaluate their use as diagnostic biomarkers, the relationship between specific exosomal miRNA levels and pathological changes of patients, including disease stage and tumor resection, was examined. Microarray analyses of miRNAs in exosome-enriched fractions of serum samples from 88 primary CRC patients and 11 healthy controls were performed. The expression levels of miRNAs in the culture medium of five colon cancer cell lines were also compared with those in the culture medium of a normal colon-derived cell line. The expression profiles of miRNAs that were differentially expressed between CRC and control sample sets were verified using 29 paired samples from post-tumor resection patients. The sensitivities of selected miRNAs as biomarkers of CRC were evaluated and compared with those of known tumor markers (CA19-9 and CEA) using a receiver operating characteristic analysis. The expression levels of selected miRNAs were also validated by quantitative real-time RT-PCR analyses of an independent set of 13 CRC patients. The serum exosomal levels of seven miRNAs (let-7a, miR-1229, miR-1246, miR-150, miR-21, miR-223, and miR-23a) were significantly higher in primary CRC patients, even those with early stage disease, than in healthy controls, and were significantly down-regulated after surgical resection of tumors. These miRNAs were also secreted at significantly higher levels by colon cancer cell lines than by a normal colon-derived cell line. The high sensitivities of the seven selected exosomal miRNAs were confirmed by a receiver operating characteristic analysis. Exosomal miRNA signatures appear to mirror pathological changes of CRC patients and several miRNAs are promising biomarkers for non-invasive diagnosis of the disease.

Introduction: Up to 30% stage I lung cancer patients suffer recurrence within 5 years of curative surgery. We sought to improve existing protein-coding gene and microRNA expression prognostic classifiers by incorporating epigenetic biomarkers. Methods: Genome-wide screening of DNA methylation and pyrosequencing analysis of HOXA9 promoter methylation were performed in two independently collected cohorts of stage I lung adenocarcinoma. The prognostic value of HOXA9 promoter methylation alone and in combination with mRNA and miRNA biomarkers was assessed by Cox regression and Kaplan–Meier survival analysis in both cohorts. Results: Promoters of genes marked by polycomb in embryonic stem cells were methylated de novo in tumors and identified patients with poor prognosis. The HOXA9 locus was methylated de novo in stage I tumors (p < 0.0005). High HOXA9 promoter methylation was associated with worse cancer-specific survival (hazard ratio [HR], 2.6; p = 0.02) and recurrence-free survival (HR, 3.0; p = 0.01), and identified high-risk patients in stratified analysis of stages IA and IB. Four protein-coding gene (XPO1, BRCA1, HIF1α, and DLC1), miR-21 expression, and HOXA9 promoter methylation were each independently associated with outcome (HR, 2.8; p = 0.002; HR, 2.3; p = 0.01; and HR, 2.4; p = 0.005, respectively), and when combined, identified high-risk, therapy naive, stage I patients (HR, 10.2; p = 3 × 10⁻⁵). All associations were confirmed in two independently collected cohorts. Conclusion: A prognostic classifier comprising three types of genomic and epigenomic data may help guide the postoperative management of stage I lung cancer patients at high risk of recurrence.

Activation of intrinsic p53 tumor-suppressor (TS) pathways is an important principle underlying cancer chemotherapy. It is necessary to elucidate the precise regulatory mechanisms of these networks to create new treatment strategies. Comprehensive analyses were carried out by microarray. Expression of miR-101 was analyzed by clinical samples of lung adenocarcinomas. We discovered a functional link between p53 and miR-101, which form a molecular circuit in response to nucleolar stress. Inhibition of RNA polymerase I (Pol I) transcription resulted in the post-transcriptional activation of miR-101 in a p53-dependent manner. miR-101 induced G2 phase-specific feedback regulation of p53 through direct repression of its target, EG5, resulting in elevated phosphorylation of ATM. In lung cancer patients, low expression of miR-101 was associated with significantly poorer prognosis exclusively in p53 WT cases. miR-101 sensitized cancer cells to Pol I transcription inhibitors and strongly repressed xenograft growth in mice. Interestingly, the most downstream targets of this circuit included the inhibitor of apoptosis proteins (IAPs). Repression of cIAP1 by a selective inhibitor, birinapant, promoted activation of the apoptosis induced by Pol I transcription inhibitor in p53 WT cancer cells. Our findings indicate that the p53-miR-101 circuit is a component of an intrinsic TS network formed by nucleolar stress, and that mimicking activation of this circuit represents a promising strategy for cancer therapy. FUND: National Institute of Biomedical Innovation, Ministry of Education, Culture, Sports & Technology of Japan, Japan Agency for Medical Research and Development.

Neurotrophic tyrosine receptor kinase (NTRK) fusions function as oncogenes and have been targeted by TRK inhibitors with excellent clinical outcomes. The international expert consensus recommends immunohistochemical (IHC) screening for TRK protein followed by next generation sequencing (NGS) to measure expression of NTRK fusions for tumors with low NTRK fusion expression. To confirm the clinical utility of this recommendation in esophageal and gastric cancers, total TRK protein expression was measured by IHC using anti-pan-TRK antibody in 254 esophageal squamous cell carcinoma (ESCC) and 401 gastric adenocarcinoma (GA) samples. Subsequently, DNA-based NGS and fluorescence in situ hybridization (FISH) were performed for tumors expressing TRK to measure NTRK fusion expression. Further, expression of NTRK fusions was evaluated in esophageal and gastric cancers using public databases. IHC staining revealed TRK was expressed in 10 out of 254 ESCC and 0 out of 401 GC cases. NGS and FISH analyses were performed for 10 TRK positive ESCC cases, identifying that none of these cases harbored NTRK fusions. In silico analyses further confirmed that NTRK fusions are rarely present in esophageal and gastric cancers. IHC screening for TRK protein is recommended to detect NTRK fusions, but this method may include many false-positives cases based on the sequencing analysis.