In summary, the genome-wide miRNA analyses on HCC tumors, adjacent non-malignant livers and cell lines revealed distinct differential miRNA expressions. In particular, the findings of deregulated miR-223 and miR-222 underscore the potential role for these microRNAs in the development of HCC. / In the functional examinations of miR-222, inhibition of miR-222 expression in Hep3B and HKCI-9 exerted no effect on cell viability. However, significant retardations on cell migration were observed in both Hep3B (64.5%, p=0.008) and HKCI-9 (52.5%, p=0.048). In Hep3B cells, functional knockdown of miR-222 was further shown to impede filopodia formation (p=0.0273). Coupling expression profiling from functional knockdown of miR-222 in Hep3B and HKCI-9 with pathway analysis, a number of miR-222 modulated pathways was suggested. Examination of such pathways, AKT and JAK/STAT, by Western blot analysis suggested profound decrease of total AKT and STAT3 protein in both Hep3B and HKCI-9. A corresponding diminution of phosphorylated AKT was also shown in both cell lines. In the examination of JAK/STAT pathway, reductions of phosphorylated STAT3 proteins were demonstrated in Hep3B and HKCI-9 following functional knockdown of miR-222. Parallel quantitative RT-PCR analysis did not suggest transcriptional changes of AKT and STAT3 mRNA between miR-222 inhibited cells and mock controls in Hep3B and HKCI-9. This in turn would be suggestive of a post-transcriptional repression of AKT and STAT3 proteins by miR-222 knockdown. Based on the functional characterization of miR-222, it would suggest the likelihood of miR-222 induction on HCC cell motility through modulation of the AKT and JAK/STAT signalling pathways. / MicroRNAs (miRNAs) are an abundant class of small, 19-25 nucleotides, non-coding RNAs with significant roles in transcriptional silencing and translational suppression. Recent studies have emphasized on a causative link between miRNA deregulations and cancer development. However, such information remains minimal in Hepatocellular Carcinoma (HCC). In an effort to characterize differentially expressed miRNAs in HCC development, global expression analyses on HCC tumors, paired adjacent non-malignant livers and HCC cell fines were carried out. Distinct miRNA expression pattern that was able to distinguish HCC tumors from non-malignant cirrhotic livers was suggested. Based on a comprehensive screening, 96 miRNAs showed differential expressions in HCC tumors, within which over 60% of miRNAs displayed increased expressions. / Six top ranked differentially expressed miRNAs, namely down-regulated miR-223, miR-126 and miR-122a, and up-regulated miR-222, miR-221 and miR-31 were subjected to further Northern blot validations. Amongst these verified candidates, miR-223 and miR-222 showed the most consistent expression changes that allowed unequivocal differentiation between HCC and non-tumoral liver (p≤0.002). The potential functional roles of miR-223 and miR-222 were subsequently investigated. Ectopic expression of miR-223 in 3 HCC cell fines, Hep3B, HKCI-C3 and HKCI-10, revealed a consistent growth inhibitory effect of 21-44% (p≤0.01). In an attempt to define potential downstream targets of miR-223, an integrative analysis of overexpressed genes from mRNA array with in-silico predictions was utilized. This approach allowed streamline of 386 targets to a candidate gene, Stathmin1 (STMN1). A significant inverse correlation between STMN1 mRNA and miR-223 expressions was demonstrated (p=0.006). At the protein level, restoration of miR-223 expressions in HCC cell lines resulted in substantial reduction of STMN1. Furthermore, miR-223 could repress the luciferase activity in reporter construct containing the putative recognition site at the STMN1 3'UTR. / Wong, Wing Lei. / Adviser: Nathalie Wong. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3450. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 163-171). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344209 |
| Date | January 2008 |
| Contributors | Wong, Wing Lei., Chinese University of Hong Kong Graduate School. Division of Anatomical & Cellular Pathology. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xix, 171 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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