טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSayag Rotem
SubjectThe Effect of Stroma Cells Originating from Different
Niches on the Growth of Mantle Cell Lymphoma
Cells
DepartmentDepartment of Medicine
Supervisors ? 10? Netanel Horowitz
? 10? Tamar Katz


Abstract

Mantel cell lymphoma (MCL) is a rare lymphoma originating in B lymphocytes and comprises 3% - 6% of Non-Hodgkin Lymphomas (NHL). The disease is usually aggressive with short-term responses to treatment, frequent recurrence and resistance to chemotherapeutic agents. New targeted therapies have been approved due to their efficacy in treating MCL. These treatments reduce disease recurrence, and act as inhibitors of several metabolic pathways in tumor cells. In addition, they might act as inhibitors of interactions in the tumor niche with the surrounding microenvironment. However, approximately one-third of patients suffer from initial drug resistance, while the other may develop resistance during therapy. Many studies have shown that stroma cells protect lymphoma cells from treatment and therefore reduce its effect.

More than 90% of patients suffer from an extranodal disease i.e. bone marrow, intestines, peripheral blood and other organs. It has been noted that the tumor environment helps the disease to thrive, and resist chemotherapy. Cell survival and migration can be affected as well. Characterizing the various niches in MCL and understanding the interaction between tumor cells and environmental cells is necessary for the development of effective therapeutic strategies to improve the survival rate in MCL patients.

This research was designed to examine the different effects of stromal cells from various niches on mantle lymphoma cells in the following phenomena associated with disease progression: cell proliferation, drug resistance, and cell migration.

The research methods included stroma and lymphoma cells co-culture, immunostaining and cell sorting using flow cytometry, cell cycle assays using Propidium iodide labeling, apoptosis assays using Annexin-PI labeling and Western blot.

We found that stroma cells reduced MCL cell proliferation with a more significant reduction in the presence of stromal cells originated from the bone marrow relative to cells from the lymph node or the colon. We hypothesized that apoptosis or cell cycle arrest could be responsible for the decrease in proliferation and the differences between the different stroma cells that we observed. We showed that there was an arrest in cell cycle phases which indicates a delay in cells entering the DNA synthesis phase, but in this context, no significant difference was found between stromal cells from various niches. We performed apoptosis assays in two different assays, Annexin-PI and Western blot. We conclude that stroma cells do not impose significant apoptosis effect on lymphoma cells in the setting of our experiments. Therefore, it appears that the reduction of MCL cell proliferation is related to cell cycle arrest. That being said, the reason for the differences between stromal cells from the various niches need to be elucidated. The effect of stroma cells from various niches on resistance to anti-cancer therapy was tested with ibrutinib. In the setting of our experiment no difference was found. We found that stroma cells enhanced cell migration, and that the most significant migration occured in the presence of stromal cells originated from the lymph node. Other experiments examining potential differences in the profile of migration related cytokines secreted from stromal cell should be performed.