Probing the role of the 37-kDa/67-kDa laminin receptor precursor/laminin receptor (LRP/LR) on the cellular viability of breast and oesophageal cancer cells by siRNA-mediated downregulation of LRP/LR

dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements of the degree of Master of Science. Johannesburg, 2014Cancer is a global burden due to high incidence and mortality rates and is ranked the second most diagnosed disease amongst non-communicable diseases in South Africa. A high expression level of the 37kDa/67kDa laminin receptor (LRP/LR) is one characteristic of cancer cells. This receptor is implicated in the pathogenesis of cancer cells by supporting tumor angiogenesis, metastasis and especially for this study, the evasion of apoptosis. In the current study, the role of LRP/LR on cellular viability of breast MCF-7, MDA-MB 231 and WHCO1 oesophageal cancer cells was investigated. Western blot analysis revealed that total LRP expression levels of MCF-7, MDA-MB 231 and WHCO1 were significantly downregulated by targeting the mRNA of LRP using siRNA-LAMR1 by 100, 44% and 73%, respectively. This knockdown of LRP expression resulted in a significant decrease of viability in the breast and oesophageal cancer cells as determined by an MTT assay by 72%, 52% and 45% in WHCO, MCF-7 and MDA-MB 231 cells, respectively. Moreover, the reduction in cellular viability was accompanied by a significant decrease in cell proliferation by 26%, 43% and 59% in MCF-7, WHCO1 and MDA-MB 231 cells, respectively. The exposure of the phosphatidylserine protein on the surface of breast MCF-7, MDA-MB 231 and oesophageal WHCO1 cancer cells as detected by the Annexin-V/7-AAD assay indicates that the reduction in cellular proliferation and viability is due to the induction of apoptosis which is elaborated by the loss of membrane symmetry as well as observations of nuclear morphological changes in all cell lines post transfection with siRNA-LAMR1. This data indicates that LRP/LR is crucial for the maintenance of cellular viability of cancerous cells and our findings recommend siRNA technology as a novel alternative therapeutic approach for the treatment of metastatic cancer