In Vitro Interactions Among Breast Cancer Cells, Osteoblasts and Megakaryocytes
Open Access
- Author:
- Chandler, Paige Nicole
- Graduate Program:
- Physiology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 17, 2013
- Committee Members:
- Andrea Marie Mastro, Thesis Advisor/Co-Advisor
Connie Jo Rogers, Thesis Advisor/Co-Advisor
Robert Paulson, Thesis Advisor/Co-Advisor - Keywords:
- breast cancer
metastasis
megakaryocytes
osteoblasts
cytokines - Abstract:
- Approximately 80% of women with advanced breast cancer will experience metastasis to bone. Bone metastases often result in skeletal fractures, spinal compression, hypercalcemia, aplastic anemia and greatly decreased quality of life. The significance of breast cancer metastasis to bone is further highlighted by the fact that 90% of cancer-related deaths occur after metastasis. One of the leading causes of death in the metastatic stage of any cancer is thromboembolism, due to the overproduction of platelets. Previously, data from this laboratory indicated that the femurs of mice bearing human metastatic breast cancer cells, a model which promotes bone metastases, contained large numbers of megakaryocytes (MKs). MKs normally comprise about 0.1% of nucleated bone marrow cells and are the progenitors of platelets. We hypothesized that when cancer cells metastasize to bone, they directly interact with MK progenitors to cause an increase in the proliferation and subsequent maturation of MKs. The objective of this study was to understand the basic interactions among breast cancer cells, osteoblasts and MKs in an in vitro system. The three aims developed to test this hypothesis are: (1) To determine the effects cancer cells have on proliferation, migration and differentiation of MKs; (2) To determine the effects that osteoblasts and cancer cells together have on MK proliferation, migration and differentiation; (3) To determine the effects that MKs have on cancer cell morphology, proliferation and migration. In order to evaluate these specific aims, MEG-01 cells (human megakaryoblastic cell line), MDA-MB-231 cells (human metastatic breast cancer cell line), MDA-MB-231BRMS1 cells (metastasis suppressed human breast cancer cell line), and NHOst cells (primary human osteoblasts) were used to make conditioned medium (CM). Conditioned medium was then used at two concentrations (10 or 50%) to observe any effects on proliferation, migration or differentiation of MEG-01 cells or MDA-MB-231 and MDA-MB-231BRMS1 cells. Cancer cell CM, from either MDA-MB-231 or MDA-MB-231BRMS1, decreased MEG-01 proliferation and increased MEG-01 multi-nucleation but had no significant effect on migration. CM from NHOst increased the proliferation and multi-nucleation of MKs but had no effect on migration. Osteoblast/cancer cell CM also increased MEG-01 proliferation and multi-nucleation but had little effect on migration. MEG-01 CM did not cause any change in the proliferation, morphology or migration of the MDA-MB-231 or MDA-MB-231BRMS1 cells. These data suggested that there may be factors secreted by both cancer cells and osteoblasts, which work to increase megakaryopoiesis and may increase malignancy. MKs do not appear to directly affect the cancer cells. By identifying how cancer cells up-regulate MKs, it may be possible to reduce megakaryopoiesis or thrombopoiesis, thereby improving quality of life after metastasis has occurred.