| Summary: | A dissertation submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in fulfilment of the requirements for the degree of Master of Science.
Johannesburg, 2013 === Cancer is a hypernym used to describe a group of diseases characterised by the
uninhibited growth and spread of abnormal cells in the body. An estimated 7.6 million
annual deaths are attributed to the disease while 12.7 million new cases are reported
every year. The severity of this disease demonstrates the urgent requirement of novel
anti-cancer therapeutic agents. The non-integrin laminin receptor, here designated the
37 kDa/67 kDa laminin receptor (LRP/LR), is a multifunctional protein located on the
surface, in the cytoplasm, in the perinuclear compartment and in the nucleus of cells.
While this receptor is imperative for normal cellular functioning, it has also been
implicated in many diseases – it serves as a cell surface receptor for numerous
viruses, infectious prion proteins as well as certain respiratory tract pathogens.
Additionally, LRP/LR has been found to have some involvement in zoonotic diseases
and those involving neurodegeneration, such as Alzheimer’s disease. Most
importantly for this study, LRP/LR has been implicated in cancer progression, where
it was found to be overexpressed on the surface of various cancer cell lines, this
overexpression correlating to increased metastasis. The aim of this study was to
investigate the effect of the siRNA-mediated downregulation of LRP expression on
the viability of tumorigenic lung and cervical cancer cells (A549 and HeLa,
respectively). The cell surface LRP/LR and total LRP levels were investigated using
flow cytometry and western blotting, respectively, in A549 and HeLa cells, the results
revealing high percentages of both cell lines expressing LRP/LR on their surface.
Additionally, A549 and HeLa cells express similar total levels LRP. The
transfectability of these cells was confirmed and siRNA-LAMR1 was shown to
significantly downregulate LRP expression (80% and 60% in A549 and HeLa cells,
respectively). MTT assays revealed that the significant 13% and 18% reduction in
cellular viability in A549 and HeLa cells, respectively, was as a consequence of LRP
downregulation. This reduction in cellular viability was found to be a consequence of
induced apoptosis (identified by the visualisation of the loss in nuclear integrity, as
well as the significantly increased activity of the apoptosis-associated protein caspase-
3) and inhibited cellular proliferation in the aforementioned cells. These findings
suggest that siRNA targeting LRP mRNA may act as a potential alternative
therapeutic tool for the teatment of cancer.
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