Significance: The ability to identify a specific cancer using minimally invasive biopsy holds great promise for improving diagnosis and prognosis. We evaluated the utility of DNA methylation profiles for differentiating tumors and normal tissues for four common cancers (lung, breast, colon, and liver) and found that they could differentiate cancerous tissue from normal tissue with >95% accuracy. This signature also correctly identified 19 of 20 breast cancer metastases and 29 of 30 colorectal cancer metastases to the liver. We report that methylation patterns can predict the prognosis and survival, with good correlation between differential methylation of CpG sites and expression of cancer-associated genes. Their findings demonstrate the utility of methylation biomarkers for the molecular characterization, diagnosis, and prognosis of cancer.

Circulating tumor DNA (ctDNA) has emerged as a useful diagnostic and prognostic biomarker in many cancers. Here, we conducted a study to investigate the potential use of ctDNA methylation markers for the diagnosis and prognostication of colorectal cancer (CRC) and used a prospective cohort to validate their effectiveness in screening patients at high risk of CRC. We first identified CRC-specific methylation signatures by comparing CRC tissues to normal blood leukocytes. Then, we applied a machine learning algorithm to develop a predictive diagnostic and a prognostic model using cell-free DNA (cfDNA) samples from a cohort of 801 patients with CRC and 1021 normal controls. The obtained diagnostic prediction model discriminated patients with CRC from normal controls with high accuracy (area under curve = 0.96). The prognostic prediction model also effectively predicted the prognosis and survival of patients with CRC (P < 0.001). In addition, we generated a ctDNA-based molecular classification of CRC using an unsupervised clustering method and obtained two subgroups of patients with CRC with significantly different overall survival (P = 0.011 in validation cohort). Last, we found that a single ctDNA methylation marker, cg10673833, could yield high sensitivity (89.7%) and specificity (86.8%) for detection of CRC and precancerous lesions in a high-risk population of 1493 participants in a prospective cohort study. Together, our findings showed the value of ctDNA methylation markers in the diagnosis, surveillance, and prognosis of CRC.

In patients with prostate cancer (PCa), bone lesions appear osteoblastic in radiographs; however, pathological fractures frequently occur in PCa patients, and bone resorption is observed in all metastatic lesions under histopathologic assessment. The mechanisms that balance the activities of osteoblasts and osteoclasts in PCa patients remain unclear. We unexpectedly discovered that PCa exosomes are critical mediators in the regulation of bone homeostasis that results in osteoclastic lesions and thereby promotes tumor growth in bone. We evaluated how exosomes derived from osteoblastic, osteoclastic, and mixed PCa cell lines affect osteoblast and osteoclast differentiation, revealing that all three types of PCa exosomes promoted osteoclastogenesis in vitro and induced osteolysis in vivo. Mechanistically, microRNAs (miRNAs) delivered by PCa exosomes were found to play several key roles in bone homeostasis. Among the delivered miRNAs, miR‐92a‐1‐5p, the most abundant miRNA, downregulated type I collagen expression by directly targeting COL1A1, and thus promoting osteoclast differentiation and inhibiting osteoblastogenesis. Furthermore, PCa exosomes also markedly reduced type I collagen expression in vivo. Our findings not only offer a novel perspective on tumor bone metastasis, where—contrary to our initial hypothesis—exosomes derived from an osteoblastic tumor induce osteoclast differentiation, but also suggest potential therapeutic targets for PCa bone metastasis.

Exosomal miR-141-3p regulates osteoblast activity to promote the osteoblastic metastasis of prostate cancer Exosomal miR-141-3p regulates osteoblast activity to promote the osteoblastic metastasis of prostate cancer

Purpose: Novel biomarkers for the diagnosis of prostate cancer (PCa) are urgently required. Increasing evidence suggests that exosomal microRNAs (miRNAs or miRs) in serum may be potential noninvasive biomarkers for certain diseases. The objective of the present study was to investigate and assess whether exosomal miR-141 is an effective biomarker for human PCa. Methods: In the present study, exosomes were isolated from the serum of patients with PCa, patients with benign prostate hyperplasia (BPH), and healthy volunteers. The total RNA was extracted from the exosomes and the level of miR-141 was analyzed by quantitative reverse transcription-polymerase chain reaction. The expression levels of miR-141 were compared between the whole serum and the serum exosomes of the three groups. Subsequently, the relevance of the exosomal expression of miR-141 to the clinicopathological factors in PCa was investigated. Results: The expression of miR-141 was higher in exosomes compared with whole serum (control group, P=0.0003; BPH group, P=0.0016; PCa group, P<0.0001). The level of serum exosomal miR-141 was significantly higher in the patients with PCa compared with the patients with BPH and the healthy controls (3.85-fold, P=0.0007 and 4.06-fold, P=0.0005, respectively). In addition, the expression levels were significantly higher in metastatic PCa compared with localized PCa (P<0.0001). Receiver-operating characteristic curve revealed that the serum exosomal miR-141 yielded an area under the curve of 0.8694, with 80% sensitivity and 87.1% specificity in discriminating patients with metastatic PCa from the patients with localized PCa. Conclusion: Serum exosomes may serve as a more suitable material compared with the whole serum for measuring circulating miR-141 levels in patients with PCa. Exosomal miR-141 is upregulated in the serum from patients with PCa compared with patients with BPH or the healthy volunteers, and it may be a useful potential biomarker for the diagnosis of metastatic PCa.