Molecular investigation of anticancer genes
File(s)
Author(s)
Masood, Motasim
Type
Thesis
Abstract
The lack of specificity of the therapeutic agents against cancer is one of the prime obstacles in developing effective therapies for the disease. The specificity of chemotherapeutic agents against cancer cells is primarily quantitative rather than qualitative. Despite the earlier success of targeted therapies, it is now clear that among an unselected population of patients, the response rate is usually limited to 10-20%. Further avenues need to be explored for the development of cancer-specific therapies. A recent concept towards such efforts is that of anticancer genes. When ectopically overexpressed, anticancer genes specifically destroy tumour cells without harming normal cells. The examples include TRAIL, MDA7, PAR4, apoptin and Orctl3. In addition, 22 novel anticancer genes were identified through systematic functional genetic screening. This thesis aimed at (i) deciphering the identity of these genes, (ii) investigating their regulation and (iii) exploring the mechanisms behind their cancer specific actions. Sanger sequencing and subsequent analyses revealed that these 22 novel anticancer genes included non-coding RNAs, novel transcripts and protein-coding genes, two among the latter are TMEFF2 and FBLN5. The expression levels of both these genes exhibit a positive correlation with the survival of breast cancer patients and both are positively regulated by FOXO3 in MCF-7 cells. FBLN5 and TMEFF2 cause cell death selectively in the COS-7 cells and not in their untransformed counterparts (CV-1 cells). Mechanistic gene expression profiling and elaborate comparison pathways analyses uncovered that FBLN5 undertakes this action putatively through the downregulation of the downstream targets of MYC and inhibition of oxidative phosphorylation. Additionally, TMEFF2 causes caspase-dependent and p53-independent apoptosis in MCF-7 cells. Gene expression profiling revealed that the TMEFF2 induces potent interferon signalling along with the upregulation of TRAIL in MCF-7 cells. TMEFF2 gives a perinuclear punctate cytoplasmic appearance in MCF-7 cells and does not co-localize with either mitochondria or α-tubulin.
Version
Open Access
Date Issued
2019-07
Date Awarded
2020-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Yagüe, Ernesto
El-Bahrawy, Mona
Publisher Department
Department of Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)