Cell-free circulating tumor RNAs in plasma as the potential prognostic biomarkers in colorectal cancer.

Background: Cell free RNA (cfRNA) contains transcript fragments from multiple cell types, making it useful for cancer detection in clinical settings. However, the pathophysiological origins of cfRNAs in plasma from colorectal cancer (CRC) patients remain unclear. Methods: To identify the tissue-specific contributions of cfRNAs transcriptomic profile, we used a published single-cell transcriptomics profile to deconvolute cell type abundance among paired plasma samples from CRC patients who underwent tumor-ablative surgery. We further validated the differentially expressed cfRNAs in 5 pairs of CRC tumor samples and adjacent tissue samples as well as 3 additional CRC tumor samples using RNA-sequencing. Results: The transcriptomic component from intestinal secretory cells was significantly decreased in the in-house post-surgical cfRNA. The HPGD, PACS1, and TDP2 expression was consistent across cfRNA and tissue samples. Using the Cancer Genome Atlas (TCGA) CRC datasets, we were able to classify the patients into two groups with significantly different survival outcomes. Conclusions: The three-gene signature holds promise in applying minimal residual disease (MRD) testing, which involves profiling remnants of cancer cells after or during treatment. Biomarkers identified in the present study need to be validated in a larger cohort of samples in order to ascertain their possible use in early diagnosis of CRC.

The diagnostic significance of CDH17-positive circulating tumor cells in patients with colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer deaths in Hong Kong. We tested the hypothesis that circulating tumor cell (CTC) analysis by ARB101 antibody could be used as a tool for CRC detection, progression, and therapy response. RESEARCH METHODS: ARB101 antibody was used for investigation of CDH17 expression in formalin-fixed, paraffin-embedded (FFPE) tissue sections and circulating tumor cells (CTCs) of CRC patients. RESULTS: Using ARB101, highest sensitivity was observed in 98/100 (98%) colorectal cancer tissue compared to 72/100 gastric cancer (72%) and 27/32 pancreatic cancer (84%). Immunoreactivity of CDH17 was significantly higher in distant metastatic (tumor-node-metastasis [TNM] stage IV) than non-distant metastatic (TNM stage I to III) CRC. ARB101 antibody also manifested the higher sensitivity than c-erbB2 (8%) and epidermal growth factor receptor (EGFR)-targeting antibodies (37%) with the significance (p < 0.0001). ARB101 positive CTCs were detected in 64/83 (77%) TNM stage I to IV CRC patients. Furthermore, ARB101 positive CTCs detected in TNM stage I to III CRC patients before and after surgical operation are statistically significant (p < 0.0001). CONCLUSIONS: CTC detection by ARB101 antibody could serve as a potential non-invasive approach for CRC detection, progression, and monitoring of treatment response.

The non-invasive diagnosis of colorectal cancer via a SOX9-based gene panel.

Colorectal cancer (CRC) threatens human health seriously. Early diagnosis of CRC is critical to improving patient survival. Meanwhile, non-invasive detection through tumor-circulating markers can be an important auxiliary diagnosis. In this study, we performed targeted RNA sequencing in paired tumor and adjacent normal fresh frozen tissues from 68 patients, and we also measured circulating mRNA levels in 4 time-point plasma samples collected before and after operation or chemotherapy. Our results showed that SOX9 (6.73-fold with adjusted p value < 1 × 10-45), MYC (20.59-fold with adjusted p value < 1 × 10-57), and MMP7 (131.94-fold with adjusted p value < 1 × 10-78) highly expressed in tumor compared with adjacent normal tissues. Besides, the circulating mRNA of SOX9 (41.14-fold with adjusted p value < 1 × 10-13) in CRC was significantly higher than in the normal control as well. Moreover, a SOX9-based 9-gene panel (SOX9, GSK3A, FZD4, LEF1, DVL1, FZD7, NFATC1, KRT19, and RUVBL1) showed the non-invasive diagnostic value of CRC (AUC: 0.863 (0.766-0.960), TPR: 0.92, TNR: 0.87). In summary, SOX9 expression consistently increases in tumor and plasma samples from CRC patients, which indicates the important role of SOX9 in CRC progression and its potential in non-invasive diagnosis of CRC.

Detection of miR-92a and miR-21 in stool samples as potential screening biomarkers for colorectal cancer and polyps.

OBJECTIVE: The detection of molecular markers in stool samples is a potential strategy for colorectal cancer (CRC) screening. This study evaluated the feasibility of detecting miR-21 and miR-92a in stool samples of patients with CRC or polyps. METHODS: The reproducibility of detection and stability of stool-based microRNA were evaluated. Stool samples were collected from 88 patients with CRC, 57 patients with colorectal polyps and 101 healthy controls. MiRNA levels in CRC tissues and stool samples were detected by real-time quantitative reverse transcription PCR. Stool miR-21 and miR-92a levels were compared before and after the removal of tumour or advanced adenoma. RESULTS: The study demonstrated that stool-based miRNA were stable with highly reproducible detection. The expression of miR-21 and miR-92a was significantly higher in CRC tissues compared with their adjacent normal tissues (p<0.0001). Patients with CRC had a significantly higher stool miR-21 level (p<0.01) and miR-92a level (p<0.0001) compared with normal controls. Stool miR-92a, but not miR-21, was significantly higher in patients with polyps than in controls (p<0.0001). At a cut-off value of 435 copies/ng of stool RNA, miR-92a had a sensitivity of 71.6% and 56.1% for CRC and polyp, respectively, and a specificity of 73.3%. In addition, the stool miR-92a level demonstrated a higher sensitivity for distal CRC than proximal CRC (p<0.05), and a higher sensitivity for advanced adenoma than minor polyps (p<0.05). Removal of tumour resulted in reduced stool miR-21 and miR-92a levels (p<0.01), and the removal of advanced adenoma resulted in a reduction of the stool miR-92a level (p<0.05). CONCLUSION: Stool miRNA are useful for screening CRC and polyps.