Breast cancer is the most commonly diagnosed cancer in women. Despite recent advances in screening and early detection, breast cancer continues to result in a high incidence of morbidity and mortality. In its late stage the majority of patients exhibit signs of destructive skeletal metastasis. This complication is promoted by the production of growth factors by tumor cells which can induce tumor cell proliferation via their interaction with their respective receptors to initiate the vicious cycle of bone resorption. Inhibition of growth factors signaling through their receptors can therefore serve as a useful therapeutic approach to block bone metastasis. / The biological characteristics of cancer cells along with the targeting properties of immune system offer a novel approach in the treatment of breast cancer. Directed against HER-2/nue oncogene, the recombinant humanized monoclonal antibody, Trastuzumab (Herceptin), has shown significant clinical benefits for the treatment of HER-2 positive metastatic breast cancer. / In the present study, the effects of Herceptin and its molecular mechanism of action in abrogating the development and progression of osteolytic bone metastasis is investigated in an experimental mouse model of skeletal metastasis using human breast cancer cells BT-474 which are known to express high levels of HER-2. Treatment of BT-474 cells with Herceptin caused a dose dependent decrease in cell proliferation. In in vivo studies BT-474 cells were injected by into the left ventricle of female BALB/c nu/nu mice. Intraperitoneal infusion of Herceptin from the day of tumor cell inoculation or at the time of radiologically detectable skeletal metastasis either slowed the development or prevented the progression of skeletal metastasis as compared to control groups of animals receiving non-specific IgG. Bone histological analysis of long bones showed the ability of Herceptin to reduce the ratio of tumor volume to bone volume as well as mitotic index when Herceptin treatment was initiated from the day of tumor cell inoculation. Immunohistochemical analysis of long bones showed a significantly lower level of activated (phosphorylated) MAPK in bones of Herceptin treated animals. These studies demonstrate the ability of Herceptin to inhibit the development and abrogate the progression of skeletal metastasis associated with breast cancer by blocking the HER-2 mediated signaling pathways.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.112523 |
| Date | January 2007 |
| Creators | Khalili Boroojeni, Parisa. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002699464, proquestno: AAIMR51291, Theses scanned by UMI/ProQuest. |
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