AbstractsBiology & Animal Science

Transient receptor potential Vanilloid 1 (TRPV1) in haematological malignancies

by SA Omari

Institution: University of Tasmania
Year: 2014
Keywords: TRPV1; haematological malignancies; capsaicin; metabolic activity; flow cytometry; Western blotting; overexpression
Record ID: 1032733
Full text PDF: http://eprints.utas.edu.au/18728/1/Front-Omari-thesis.pdf



Transient receptor potential vanilloid-1 (TRPV1) is a member of the TRP family of channels that are responsible for nociceptive, thermal and mechanical sensations. It is primarily associated with neuronal cells, but has been detected in different non-neuronal cells, including leukocytes. Capsaicin (CAP), the active ingredient of hot chilli peppers, is one of a number of related endogenous and plant-derived compounds (broadly termed ‘vanilloid-like agents’) that have been shown to induce apoptosis and inhibit cell proliferation in some cancer cells, through both TRPV1-dependent and -independent mechanisms. The expression and function of TRPV1 in haematological malignancies however, has not been extensively investigated. Specific targeting by vanilloid-like agents toward TRPV1 on cancerous cells in patients with haematological malignancies may represent a novel therapeutic approach to treating these diseases. This thesis investigated the expression and function of TRPV1 in haematological malignancies, using both blood cancer cell lines and blood samples obtained from patients with different blood cancers. The specific aims were to; 1) study the effect of TRPV1 agonists and antagonists on the viability of THP-1, U266B1 and U937 haematological malignant cell lines, 2) validate and optimise Western blotting and flow cytometry protocols to detect TRPV1 expression in leukocytes, 3) investigate TRPV1 expression in THP-1, U266B1 and U937 cells, and 4) compare TRPV1 expression in leukocytes obtained from patients with blood cancers to normal subjects. The thesis begins with a comprehensive review and discussion on TRPV1 structure and function, as well as its expression and role in health and disease. In particular, there is a focus on the role of TRPV1 in cancer, including haematological malignancies (Chapter 1). In Chapter 2, the effect of CAP on the metabolic activity of three malignant haematological cell lines, THP-1, U266B1 and U937, was investigated. Metabolic activity assays were performed using the alamarBlue® method. CAP induced cytotoxicity in all three cell lines in a concentration-dependent manner. A biphasic effect on metabolic activity was observed on THP-1 cells [EC50, IC50 (95% CI) = 32.9 (19.9-54.3), 219 (144-246) μM]. U266B1 cells were more resistant to CAP-induced death than THP-1 and U937 cells. TRPV1 and CB1 antagonists (SB452533 and AM251, respectively) suppressed the CAP-induced increase in THP-1 cell metabolic activity (P<0.001). These experiments suggest that CAP inhibits the metabolic activity of malignant haematological cells through a non-TRPV1-dependent mechanism. Chapters 3 and 4 represent the experimental work and trouble-shooting conducted to develop, validate and optimise methods for the detection of TRPV1 expression in human cells. Western blotting (Chapter 3) and flow cytometric (Chapter 4) methods have been previously published, however few have documented the use of appropriate controls for the detection of TRPV1, suggesting that data in the literature may not necessarily be valid. A…