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Title: The effects of snake venoms as cytotoxins on selected prostate cancer cell lines
Author: Abdalsaed, Basher M.
ISNI:       0000 0004 6499 6708
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2017
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Cancer is expected to claim 9 million deaths world-wide by the year 2020. Although there has been an increase in the sophistication of current therapeutic strategies, 40% of patients are still likely to die from the disease. Novel anticancer compounds are needed. Snake venoms may represent a relevant pool for selecting candidates that may have anticancer properties. Snake venoms are complex mixtures of unexplored sources of molecules with potential use in biomedical research and drug development. Some venom molecules are of low molecular weight and might trigger anticancer responses and could have potential therapeutic applications. In this study, selected snake venoms obtained from Naja pallida, Agkistrodon piscivorus conanti and Agkistrodon contortrix laticinctus were evaluated for cytotoxicity and selectivity in vitro against a panel of prostate cancer cell lines (DU145, PC3, LNCaP) and a non-malignant prostate epithelial cell line (PNT2A). The cytotoxicity activity of each venom was initially assessed using the SYTOX Green assay. SYTOX Green is a fluorescent nucleic acid indicator dye that can be used as a marker for cell death. The whole venoms, fractions and sub-fractions of Naja pallida, Agkistrodon piscivorus conanti and Agkistrodon contortrix laticinctus were tested and found to have activity ranging that from 0.1-20μg/ml against prostate cancer cell lines using an assay based on the release of lactate dehydrogenase (LDH). Further characterization of cytotoxic activity, and chemical analysis, including High Performance Liquid Chromatography (HPLC) guided fractionation, gel filtration and ion exchange chromatography has been conducted. The investigation of the possible mode of activity of the most cytotoxic venoms, and prospects for future work and on-going isolation and identification of pure anticancer compounds have been detailed in this study. The different fractions of low molecular weight (< 15kDa) were further fractionated using a C18 reverse phase HPLC column and tested for activity against the prostate cell lines. The N-terminal amino acid sequences of the first residues of active pure fractions from Naja pallida venom were P4F3-2 LKXNQLIPPFWKTXP and P4F4-1 LKXNKLIPIA YKTXPEGKNLXYK. These N-terminal sequences show homology with the group of cobra cytotoxins/ cardiotoxins from the family Elapidae and are likely to be identical to two known cytotoxins, cardiotoxin γ from N. pallida and cardiotoxin 4 from N. mossambica. Another peptide had an N-terminal sequence similar to a phospholipase A2. These peptides were tested for specific cytotoxic activities against on the cell lines by the LDH assay. Fraction P4F4 at 5 and 10μg/ml had strong cytotoxic activity on DU145 and PC3 cells, but less activity on LNCaP cells and no activity on the non-cancer PNT2A cells. The sub-fractions P4F4-1 and P4F4-2 had marked effects on PC3 cells, lesser effect on LNCaP cells and no effect on DU145 and PNT2A cells. Further characterisation is needed, but this may be the first report of cytotoxins with possibly selective anticancer cell activity isolated from the venom of red spitting cobra Naja pallida.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral