THE ROLE OF CELL ADHESION MOLECULES AND MATRIX METALLOPROTEINASES IN OSTEOSARCOMA METASTATIC POTENTIAL
Open Access
- Author:
- Roopnariane, Adriana P
- Graduate Program:
- Genetics
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Timothy M Ritty, Thesis Advisor/Co-Advisor
Timothy M Ritty, Thesis Advisor/Co-Advisor - Keywords:
- Matrix Metalloproteinase
Osteosarcoma
Integrin - Abstract:
- Abstract Osteosarcoma (OS) is the most common bone cancer and the second greatest cause of cancer related death in children behind blood cancers. The American Cancer Society reports that the five year survival rate of patients with metastatic osteosarcoma is 30% even with the use of adjuvant or neo-adjuvant chemotherapy. Although, in the last 30 years there has been significant improvement in osteosarcoma of the extremities, 30-40% patients relapse within three years. Even though the use of adjuvant and neo- adjuvant chemotherapy beginning in the 1980’s has increased survival, progress has since plateaued. Work presented in this thesis specifically focuses on the role of integrin induced matrix metalloproteinases in OS metastasis. We hypothesize that the integrin-MMP expression feedback loop is a mechanism whereby metastasizing osteosarcoma cells can produce specific proteolytic enzymes required for invasion. This model predicts that integrin-mediated cell adhesion to different ECM proteins will result in the expression of different MMPs by the OS cell. To test this hypothesis, we have developed osteosarcoma lines that express high and low levels of the α2 integrin subunit. Our results demonstrate that loss of the α2 integrin subunit results in de-repression of MMP 1 and MMP 3 when grown on non-matrix substrate (plastic) and matrix substrates (fibronectin and collagen). Our data suggest a relationship between integrin ligation of specific ECM proteins and subsequent changes in MMP protein expression. Secondly, we hypothesize that the metastatic potential of OS is influenced by the type and amount of integrin receptors present on osteosarcoma cells. To test this hypothesis, we have evaluated the integrin profile of two osteosarcoma cell lines of low (SAOS-2) and high (LM7) metastatic potential. We found that the metastatic sub-line LM7 has lower alpha 5 integrin subunit levels when compared with the non-metastatic parental SAOS-2 cell line. This reduced alpha 5 integrin subunit expression may implicate this integrin in the metastatic process of osteosarcoma. Further, we also present data on MMP expression in the SAOS-2 parental cell line compared with the LM7 cell line. In this study, we show that the LM7 cell line expresses significantly less MMP 2 when plated on plastic and matrix substrates. Reduced MMP 2 expression in the LM7 cell line may suggest aberrant MMP 2 regulation in osteosarcoma metastasis. Finally, due to the lack of osteosarcoma cell lines, we have isolated and partially characterized a primary osteosarcoma cell line from a patient diagnosed with Marfan Syndrome called Penn State University-Osteosarcoma-Marfan syndrome (PSU-OS-M). We have selected for tumor cells without chemical or viral induction unlike most of the OS research cell lines available. The PSU-OS-M cell line was successfully cultured in vitro and the cells were shown to exhibit attachment independent growth and loss of contact inhibited growth when cultured on plastic (hallmarks of transformation). We hope the establishment of this osteosarcoma cell line will better reflect human osteosarcoma. Since mutations in the fibrillin-1 gene are responsible for Marfan syndrome, we evaluated fibrillin-1 expression. Using immunoflorescent analysis, we observed reduced fibrillin deposition but normal fibronectin deposition in the PSU-OS-M cell line.