وثيقة

The impact of long non-coding RNAs on gene expression regulation and pathogenesis mechanisms in ovarian cancer through emerging molecular and bioinformatic analysis.

المصدر
Doctoral dissertation
عناوين أخرى
تأثير الأحماض النووية الرايبوزية الطويلة غير الُمشفرة على تنظيم تعبير الجينات وآليات مسببات المرض في سرطان المبيض من خلال التحليل الجزيئي الحيوي والمعلوماتي
الدولة
Oman
مكان النشر
Muscat
الناشر
Sultan Qaboos University
ميلادي
2024
اللغة
الأنجليزية
نوع الرسالة الجامعية
Doctoral dissertation
الملخص الإنجليزي
Background: Epithelial Ovarian cancer (EOC) is a lethal gynecological malignancy, commonly regarded as a silent killer. The majority (80%) of the EOC patients are diagnosed at the late stages due to the absence of reliable biomarkers, which along with the resistance to drug treatment and recurrence are the major causes for the poor overall survival. Hence, it is imperative to identify biomarkers for early EOC detection and for better survival outcomes. In our previous study, we conducted chromatin immunoprecipitation (ChIP) using E2F5, a transcription factor known for its high expression in early-stage EOC, to identify candidate genes potentially involved in EOC pathogenesis. Through ChIP analysis, we discovered several E2F5 downstream target genes (FBXW7, FAT4, ARID1A), including non-coding RNAs (ncRNAs). Long noncoding RNAs (lncRNAs), may play a role in cancer development and could potentially serve as biomarkers for early cancer diagnosis. However, the precise role of lncRNAs in EOC remains largely unexplored, impeding our understanding of their involvement in gene regulation mechanisms. Materials and Methods: To investigate the downregulation mechanism of E2F5 target genes (FBXW7, FAT4, ARID1A), we employed gene panel exome sequencing, and conducted bioinformatic analysis. Also, methylation-specific PCR (MSP) was performed to analyze the methylation status of FBXW7. Additionally, to assess the functional role of the E2F5 downstream target lncRNA LINC01465, we performed cell proliferation, invasion, and wound healing assays. Furthermore, to identify differentially expressed lncRNAs in primary EOC samples compared to recurrent EOC samples, we conducted bioinformatics analysis using data from The Cancer Genome Atlas (TCGA) database, employing the GDCRNA Tools in R program. Among the differentially expressed lncRNAs, we selected the lncRNA AC243964.2 as a potential candidate for further validation in EOC cell lines. Similarly, analysis using the GEPIA database revealed significantly dysregulated lncRNA (RFX5-AS1), which we further validated in EOC cell lines. Moreover, we quantified the expression of LINC01465, AC243964.2, and RFX5- AS1 in Malformin A1 (MA1)-treated EOC cells to investigate its potential role in modulating drug resistance. Lastly, we monitored the differential expression of AC243964.2 and RFX5-AS1 in HOSE 6-3 cells treated with extracellular vesicle enriched media from OVSAHO cells, and vice-versa. To investigate potential of extracellular vesicles, including exosomes, to reverse the cellular phenotype, we measured the alterations in the expression levels of mesenchymal marker SNAI1 and epithelial marker E CAD in HOSE 6-3 cells treated with extracellular vesicles derived from OVSAHO VIII cells, and vice-versa. Results: Consistent with in-silico analysis, EOC samples did not exhibit FBXW7 methylation. Furthermore, there was an absence of mutation/deletion in the FBXW7, FAT4, and ARID1A genes, indicating an alternative regulatory mechanism involving ncRNAs responsible for their suppression. Consequently, we chose to investigate the functional role of the lncRNA LINC01465, a downstream target of E2F5, in EOC cell lines. Silencing of LINC01465 resulted in reduced migratory ability in SKOV3 and OVSAHO cells, suggesting an oncogenic function. Furthermore, upregulation of LINC01465 was observed in MA1-treated A2780 S and A2780 CP cells, which correlated with increased levels of CASPASE-1, promoting cell death through pyroptosis in A2780 S and A2780 CP cells. Regarding the functional analysis of AC243964.2, inhibiting its expression in OVSAHO cells resulted in a decreased number of colonies compared to the control group (NC). Moreover, while there was a decrease in the expression of ATG5, FOXM1, and the anti-apoptotic marker BCL2, the expression of CASPASE-9 and TP53 increased at the RNA levels. Additionally, BCL2, BCL-XL, and the apoptotic marker CASPASE-3 were downregulated at the protein level, while FOXM1 was overexpressed, suggesting a potential role of AC243964.2 in oncogenesis. In terms of RFX5-AS1, downregulation of SOD2 expression was observed in RFX5-AS1-silenced A2780 CP cells, while RFX5-AS1-silenced OVSAHO cells exhibited lower levels of YAP1 and SOD2. Furthermore, RFX5-AS1 was upregulated, while AC243964.2 levels were lower in MA1-treated A2780 CP and OVSAHO cells compared to untreated cells. Additionally, the expression of AC243964.2, RFX5-AS1, and AC061992.1 lncRNAs was higher in HOSE 6-3 cells treated with extracellular vesicle-enriched media from OVSAHO. Conversely, downregulation in the expression of AC243964.2 and AC061992.1 was observed in OVSAHO cells treated with extracellular vesicle-enriched media from HOSE 6-3 cells. In terms of the epithelial-mesenchymal transition (EMT) markers, we observed a decrease in the epithelial marker E CAD in HOSE 6-3 cells treated with extracellular vesicles enriched media from OVSAHO cells, while the mesenchymal marker SNAI1, was upregulated. Conclusion: Our study uncovers the novel roles of the lncRNAs LINC01465, AC243964.2, and RFX5-AS1 in regulating EOC. Based on our findings, we propose that the lncRNA LINC01465 may play a crucial role in MA1-induced cell death through CASPASE-1-mediated pyroptosis. Additionally, the lncRNA AC243964.2 could influence EOC progression by modulating apoptotic and autophagy pathways. Regarding RFX5-AS1, its regulatory mechanism in ovarian carcinogenesis may involve the YAP1 and SOD2 pathways. Dysregulation of these pathways can lead to uncontrolled cell growth and tumorigenesis, underscoring their significance as targets for cancer research and therapy. Moreover, the field of exosomes is rapidly evolving and holds great promise for biomarker detection, disease diagnosis, and treatment. Future efforts should focus on further elucidating the underlying molecular mechanisms regulated by these lncRNAs, validating their roles as biomarkers, and developing effective strategies to combat this devastating disease.
قالب العنصر
الرسائل والأطروحات الجامعية

مواد أخرى لنفس المؤلف

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Malgundkar, Shika Hanif.
Sultan Qaboos University
2019

مواد أخرى لنفس الموضوع

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Sultan Qaboos University
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Malgundkar, Shika Hanif.
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