Purpose: Gut microbiota have been implicated in the development of colorectal cancer. We evaluated the utility of fecal bacterial marker candidates identified by our metagenome sequencing analysis for colorectal cancer diagnosis.Experimental Design: Subjects (total 439; 203 colorectal cancer and 236 healthy subjects) from two independent Asian cohorts were included. Probe-based duplex quantitative PCR (qPCR) assays were established for the quantification of bacterial marker candidates.Results: Candidates identified by metagenome sequencing, including Fusobacterium nucleatum (Fn), Bacteroides clarus (Bc), Roseburia intestinalis (Ri), Clostridium hathewayi (Ch), and one undefined species (labeled as m7), were examined in fecal samples of 203 colorectal cancer patients and 236 healthy controls by duplex-qPCR. Strong positive correlations were demonstrated between the quantification of each candidate by our qPCR assays and metagenomics approach (r ¼ 0.801-0.934, all P < 0.0001). Fn was significantly more abundant in colorectal cancer than controls (P < 0.0001), with AUROC of 0.868 (P < 0.0001). At the best cut-off value maximizing sum of sensitivity and specificity, Fn discriminated colorectal cancer from controls with a sensitivity of 77.7%, and specificity of 79.5% in cohort I. A simple linear combination of four bacteria (Fn þ Ch þ m7-Bc) showed an improved diagnostic ability compared with Fn alone (AUROC ¼ 0.886, P < 0.0001) in cohort I. These findings were further confirmed in an independent cohort II. In particular, improved diagnostic performances of Fn alone (sensitivity 92.8%, specificity 79.8%) and four bacteria (sensitivity 92.8%, specificity 81.5%) were achieved in combination with fecal immunochemical testing for the detection of colorectal cancer.Conclusions: Stool-based colorectal cancer-associated bacteria can serve as novel noninvasive diagnostic biomarkers for colorectal cancer.

Two types of molecular tests have been established to assess the deficiency of the DNA mismatch repair (MMR) system: microsatellite instability (MSI) and immunohistochemical (IHC) analysis. We have developed a reliable method to analyze the MSI status by next-generation sequencing (NGS) based on read-count distribution. A total of 91 patients with primary colorectal cancer were recruited. These patients included 54 cases with loss of expression of any MMR protein in IHC, suggesting deficient MMR (dMMR), and 37 cases of colorectal cancer with staining of all four MMR proteins in IHC, suggesting proficient MMR in the sample after surgery. DNA was extracted from paired tumor-normal tissue for MSI detection by both the ColonCore NGS panel and PCR. The sequencing data from the NGS panel was processed using various MSI detection pipelines for a comparison with the ColonCore panel. Using the MSI-PCR test as the gold standard, MSI-ColonCore achieved 97.9% sensitivity (47 of 48) and 100% specificity (37 of 37) for the detection of MSI status. MSI-ColonCore also showed more efficient and robust performance compared with other NGS-based MSI detection algorithms. The concordance rate was 92.3% between MSI-ColonCore and IHC testing, and 93.4% between MSI-PCR and IHC testing. These results suggest that MSI-ColonCore is a reliable and robust method for MSI status detection by NGS based on read-count distribution.

The gastrointestinal (GI) tract is not a common site of metastasis in primary lung cancer. The aim of the present study was to reveal the clinical and prognostic characteristics of gastrointestinal metastases of lung cancer (GMLC). Information on 366 cases of GMLC was collected and factors that affect severe GI complications were analyzed. Univariate and multivariate survival analyses were performed using the Cox proportional hazards model. Of the cases analyzed, the small intestine (59.6%) and colorectum (25.6%) were the two organs where lung cancer was most likely to metastasize in the GI tract. Squamous cell carcinoma (28.5%), adenocarcinoma (27.6%) and large cell carcinoma (20.9%) were the three most common histological types. However, compared with the histological distributions of primary lung cancer, patients with large cell carcinoma exhibited the highest elevated risk of GMLC [relative risk (RR), 4.07; P<0.001] and those with adenocarcinoma exhibited the lowest risk (RR, 0.58; P<0.001). Differences in organ involvement and in histological type led to varying GI complications. It was also indicated that chemotherapy was associated with a decreased risk of hemorrhage (P=0.006), but there was no reduction in the risk of hemorrhage associated with perforation and obstruction (P>0.05). The median overall survival time of GMLC patients was 2.8 months (range, 0–108 months). The survival analyses revealed that perforation and extra-GI metastasis were negative prognostic factors but abdominal surgery was identified a positive prognostic factor. In conclusion, the histological distribution of GMLC differed from that of primary lung cancer. Sufficient and careful patient evaluation, targeted surgeries and systemic therapies for specific patients are able to increase patient survival rate and improve the quality of life.

Macrophage polarization is a highly plastic physiological process that responds to a variety of environmental factors by changing macrophage phenotype and function. Tumor-associated macrophages (TAMs) are generally recognized as promoting tumor progression. As universal regulators, microRNAs (miRNAs) are functionally involved in numerous critical cellular processes including macrophage polarization. Let-7b, a miRNA, has differential expression patterns in inflamed tissues compared with healthy controls. However, whether and how miRNA let-7b regulates macrophage phenotype and function is unclear. In this report, we find that up-regulation of let-7b is characteristic of prostatic TAMs, and down-regulation of let-7b in TAMs leads to changes in expression profiles of inflammatory cytokines, such as IL-12, IL-23, IL-10 and TNF-α. As a result, TAMs treated with let-7b inhibitors reduce angiogenesis and prostate carcinoma (PCa) cell mobility. Let-7b may play a vital role in regulating macrophage polarization, thus modulating the prognosis of prostate cancer.