The development of novel metabolic therapies for the treatment of glioblastoma

Glioblastoma is the most common type of adult brain tumour, with a dismal median patient survival of only 15 months. With significant side effects further associated with the current standard of care, there is a desperate need for effective new therapies capable of selectively targeting this tumour. One potential solution is to exploit abnormal metabolic process unique to glioblastoma cells, which play a key role in promoting their rapid unregulated growth and survival. This led to the central aim of this thesis, which was to assess the feasibility of targeting components integral to increased glycolysis and glutamine utilisation in glioblastoma as a potential new therapeutic strategy. RT-qPCR analysis revealed a large number of established glioblastoma cell lines and patient derived short-term cell cultures to upregulate expression of the key first rate-limiting enzyme of glycolysis, HK2. HK2 knockdown was further demonstrated to significantly inhibit the glycolytic activity of these cell cultures upon the seahorse XFp. These findings importantly reaffirmed HK2’s role as a key driver of the elevated glycolysis unique to glioblastoma. Efforts to translate a HK2-directed therapy have been stalled by the current lack of a clinically suitable specific inhibitor. MTT and spheroid reformation cytotoxicity assays conducted on glioblastoma cell cultures with varying levels of HK2 expression showed that the prospective HK2 inhibitors posaconazole, ketoconazole, and xanthohumol lack selectivity towards their intended target. RNAseq of HK2 knockdown cell cultures revealed novel associations between HK2 and chronic inflammation, immune infiltration, and angiogenesis in the glioblastoma tumour microenvironment. This sequencing data was also utilised to identify several ‘matching’ compounds that induce expression changes comparable to HK2 knockdown, which could be explored as alternative HK2-selective inhibitors as part of future research. Further RT-qPCR analysis of patient biopsies indicated that glioblastoma tumours upregulate their uptake of glutamine through overexpressing the transporter ASCT2. Key rate-limiting enzymes involved in the utilisation of glutamine for de novo nucleotide synthesis (PPAT, CAD) were upregulated in the large majority of tumour biopsies, while those involved in glutaminolysis (GLS1, GLS2) were near-universally downregulated. In summary, the data of this thesis reinforced HK2’s potential as a therapeutic target for disrupting glioblastoma glycolysis, while also highlighting co-targets that could be exploited in combination with existing immuno- and anti-angiogenic therapies. This thesis’s findings also point toward glioblastoma tumours increasing their uptake of glutamine to fuel nucleotide synthesis, which subsequently represents another exciting target for metabolic therapy going forward.

Citation

Edwards, C. (2025) The development of novel metabolic therapies for the treatment of glioblastoma. University of Wolverhampton. https://wlv.openrepository.com/handle/2436/626041

Publisher

University of Wolverhampton

URI

https://wlv.openrepository.com/handle/2436/626041

Type

Thesis or dissertation

Language

en

Description

A thesis submitted in fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy.

Collections

Theses and Dissertations