Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Health Technology and Informatics | en_US |
| dc.contributor.advisor | Wong, Cesar (HTI) | - |
| dc.creator | Xue, Weiwen | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/9563 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | - |
| dc.rights | All rights reserved | en_US |
| dc.title | Investigate non-invasive early-diagnostic and prognostic biomarkers of colorectal cancer using targeted RNA sequencing | en_US |
| dcterms.abstract | This study aims to find circulating messenger RNA (mRNA) markers for early diagnoses of colorectal adenoma and diagnoses and potential prognoses of colorectal cancer (CRC) based on next-generation sequencing (NGS). In this study, the expression of a panel of 108 CRC-related genes was measured using targeted mRNA sequencing in plasma and tissue samples from normal, colorectal adenoma and CRC patients. Firstly, I studied how different centrifugal forces affect CRC-related mRNA in plasma samples. Targeted mRNA sequencing was used to profile gene expression in 18 healthy donors' plasma samples prepared by 1) 3,500g for 10 minutes at 4°C; and 2) 1,600g for 10 minutes at 4°C followed by 16,000g for 10 minutes at 4°C. Results showed that 75/108 (69.4%) and 86/108 (79.6%) CRC-related genes were detectable in 3,500g and 1,600g followed by 16,000g plasma samples, respectively. Besides, MYC and HIF1A as differential expressed genes (DEGs) were identified by a cut-off as fold change > 4 and adjusted P value < 0.05 based on sequencing data. Secondly, I studied non-invasive early-diagnostic markers for colorectal adenoma. Plasma samples from 39 normal and 40 colorectal adenoma patients were collected. Results showed that GSK3A as the only DEG was identified by a cut-off as fold change > 4 and adjusted P value < 0.05 based on sequencing data, and its expression in colorectal adenoma was significantly lower than those in normal plasma samples (0.01-fold with adjusted P < 0.05). Thirdly, I studied non-invasive diagnostic and potential prognostic markers for CRC. Plasma samples from 65 CRC patients were collected in multiple time points for targeted mRNA sequencing to find candidate genes as non-invasive diagnostic or potential prognostic markers. Results showed that in the comparison between before surgery CRC and normal plasma samples, 22 DEGs were identified by a cut-off as fold change > 4 and adjusted P value < 0.05 based on sequencing data. Among them, TWIST1 and DVL1 showed the most significant up- (41.150-fold change with adjusted P < 1×10⁻¹³) and down-regulation (0.004-fold change with adjusted P < 1×10⁻¹²) in before surgery CRC samples compared with normal samples, respectively. In the comparison between after surgery and before surgery CRC plasma samples, 4 DEGs were identified. All DEGs showed up-regulation in after surgery samples compared with before surgery samples, and FZD4 showed the most significant up-regulation (28.955-fold change with adjusted P < 1×10⁻⁶). In the comparison between before chemotherapy and after surgery CRC plasma samples, 3 DEGs were identified. All DEGs showed down-regulation in before chemotherapy samples compared with after surgery samples. Finally, I validated gene expression in 68 pairs of tumor and adjacent normal tissues to study whether differential expression of candidate markers was tumor-derived. Results showed that 23 DEGs were identified by a cut-off as fold change > 4 and adjusted P value < 1 × 10⁻¹⁰, and the differential expression of MYC and SOX9 in tumor and adjacent normal tissues was confirmed by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Besides, the differential expression of WISP1 was confirmed by RT-qPCR in formalin-fixed, paraffin-embedded (FFPE) tissue samples from normal, colorectal adenoma with different grade of dysplasia and CRC. Information obtained in this study provides candidate non-invasive early-diagnostic markers for colorectal adenoma and diagnostic and potential prognostic markers for CRC, and it may promote the translation of targeted sequencing data of plasma samples into clinical practice. | en_US |
| dcterms.extent | xx, 191 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2018 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.LCSH | Colon (Anatomy) -- Cancer -- Diagnosis | en_US |
| dcterms.LCSH | Rectum -- Cancer -- Diagnosis | en_US |
| dcterms.accessRights | open access | en_US |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 991022144642903411.pdf | For All Users | 9.71 MB | Adobe PDF | View/Open |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/9563