Loss of chaperone protein in human cancer

Thesis

TRAP1 is a Heat Shock Protein (HSP) chaperone to retinoblastoma but also associated to the tumor necrosis factor receptor. HSPs are primarily up regulated in cancer. Work in our lab noted a down regulation of TRAP1 in some non-small cell lung cancers compared to normal lung. The first aim of this project was to evaluate the effect of the loss of TRAP1 on cell proliferation using a spheroid model. The presence of TRAP1 in spheroids promoted cell proliferation and a faster onset of hypoxia. This suggests an oncogenic role for TRAP1 since rapid hypoxia development equates to poor prognosis.

Micro array analysis showed that TRAP1’s loss was associated with increased transcrpition of the Junctional Mediating and Regulatory protein (JMY). JMY possesses an oncogenic property due to its ability to facilitate cell motility. Additionally it has tumor suppressor activity in promoting p53 activation. The second aim of this project was to produce an anti-JMY antibody and use it to characterize JMY and additionally verify the association between TRAP1 and JMY.

JMY was found to be widely expressed in normal tissues and in many types of tumors. In neoplastic tissues, comparing primary versus metastatic tumors, JMY was found to have significantly higher expression in the metastatic compared with the primary tumors. A pilot study showed that nuclear co-expression of JMY and P53 was associated with shorter overall survival suggesting that a possible tumorigenesis mechanism could be via a deregulation/mutation of JMY/p53 or both.

Finally, using 3 dimensional constructions, I demonstrated the distinct morphological difference between an angiogenic tumor and a non-angiogenic tumor. Additionally, I showed a characteristic cytoplasmic p53 sequestration in the non-angiogenic phenotype that is absent in the angiogenic phenotype. This could be the mechanism that the non-angiogenic tumor uses to adapt to hypoxia. This would imply that there is a potential for cancers to escape therapy by switching between these 2 phenotypes.

Authors: Adighibe, O

• Publication date: 2012
• DOI: 10.5287/ora-beqmq5o8z
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: TRAP1; angiogenesis; heat shock proteins; JMY
• Subjects: Clinical laboratory sciences; Molecular haematology; Tumour pathology