Breast Cancer Cell Chemoattractants Derived From Osteoblasts
Open Access
- Author:
- Campo, Dianalee A.
- Graduate Program:
- Physiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- July 01, 2005
- Committee Members:
- Carol V Gay, Committee Chair/Co-Chair
Ronald Scott Kensinger, Committee Member
Roland M Leach, Committee Member
Andrea Marie Mastro, Committee Member - Keywords:
- Chemoattraction
Osteonectin
RGD
Breast Cancer
Bone
Metastasis - Abstract:
- Metastatic breast cancer cells have an increased propensity to metastasize to bone. Whether bone has a unique chemotactic potential that attracts breast cancer cells is addressed in this study. Osteonectin has been characterized as a possible bone-derived chemoattractant. Through a series of protein analyses for molecular size, glycosylation, phosphorylation, and amino acid sequence, we determined that there was no detectable unique configuration of bone-derived osteonectin. Although osteonectin did increase cell motility, it did not cause the cancer cells to migrate in a directed manner. Osteonectin did not induce directed cell migration of breast cancer cells in transwell migration assays. Although breast cancer cells were not attracted to osteonectin, they were attracted to and migrated toward the mineralized portion of bone matrix (bone extracts). We first assayed the bone extracts for the presence of other bone matrix proteins and confirmed the presence of fibronectin, vitronectin, osteopontin and bone sialoprotein. Through transwell migration assays, it was also confirmed that breast cancer cells migrated toward fibronectin, vitronectin and osteopontin; this migration was RGD-dependent. We then determined that the breast cancer cell attraction and migration toward bone extracts was also RGD-dependent. The next aim of the dissertation was to analyze the soluble portion of bone. The soluble portion of bone was collected in the form of conditioned media from an osteoblast cell culture. We demonstrated that breast cancer cells were also attracted to and migrated toward osteoblast-conditioned media. This migration was not RGD-dependent and was correlated to the concentration of the chemokine, RANTES. We concluded that osteonectin was not a chemoattractant that directed beast cancer cell migration but increased random cellular motility. In contrast, RGD-containing proteins, namely fibronectin, vitronectin and osteopontin attracted breast cancer cells and may contribute to their preferential metastasis to bone. In addition to the RGD-containing proteins, osteoblasts also secreted unidentified soluble factors that attracted breast cancer cells.