αvβ3 Integrin Expression and Mitogenic Effects by Thyroid Hormones in Chronic Lymphocytic Leukemia

Area of Science:

• Hematology
• Oncology
• Endocrinology

Background:

• Chronic lymphocytic leukemia (CLL) is the most common adult leukemia.
• Thyroid hormones (T3, T4) are known to promote tumor growth in various cancers by activating alpha-v-beta-3 integrin (αvβ3) and phosphorylating ERK (pERK).
• The role of thyroid hormones and αvβ3 in CLL has not been previously investigated.

Purpose of the Study:

• To investigate the expression of αvβ3 integrin in CLL cells.
• To determine the effect of thyroid hormones (T3, T4) on αvβ3 expression and signaling pathways in CLL.
• To explore the potential mitogenic role of thyroid hormones in CLL.

Main Methods:

• Primary CLL cells from 22 patients were analyzed for disease markers and αvβ3 expression using flow cytometry, ImageStream, Western blots, and immunohistochemistry.
• Archival bone marrow and lymph node tissues were also examined.
• Selected samples were treated with T3 or T4, and the expression of αvβ3, pERK, and PCNA was measured by Western blot.

Main Results:

• αvβ3 integrin was detected on the surface of circulating CLL cells and in bone marrow, but not in lymph nodes.
• Exposure to T3 and T4 significantly increased αvβ3 protein levels in primary CLL cells.
• Thyroid hormones rapidly induced the expression of pERK and PCNA, indicating increased cell proliferation.

Conclusions:

• αvβ3 integrin is present on primary CLL cells and its expression is upregulated by thyroid hormones.
• Thyroid hormones likely act as mitogens in CLL cells, potentially through αvβ3-mediated signaling pathways.
• These findings suggest αvβ3 integrin as a potential therapeutic target in CLL.