Pituitary tumours without distinct lineage differentiation express stem cell marker SOX2

Area of Science:

• Endocrinology
• Oncology
• Cell Biology

Background:

• The 2022 WHO Classification introduced a new category: plurihormonal tumors without distinct lineage differentiation (WDLD). These tumors are characterized by expressing multiple transcription factors in a uniform cell population.
• Understanding the cellular origins of WDLD tumors is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate the expression of stem cell markers (SOX2, Nestin, CD133) in WDLD pituitary tumors.
• To compare stem cell marker expression in WDLD tumors with those of immature PIT-1 lineage, acidophil stem cell tumors, and lineage-committed tumors.

Main Methods:

• Retrospective analysis of surgically resected pituitary tumors.
• Immunohistochemistry and RT-qPCR were used to assess transcription factors (SF-1, PIT-1, T-PIT) and stem cell markers (SOX2, Nestin, CD133).
• Comparison of stem cell marker expression between WDLD tumors and lineage-differentiated tumors.

Main Results:

• Immunohistochemistry revealed significantly higher SOX2 expression in WDLD tumors (70%) compared to lineage-differentiated tumors (23.4%, p=0.005).
• CD133 was positive in 20% of WDLD tumors but absent in lineage-differentiated tumors (p=0.003).
• RT-qPCR showed no significant difference in stem cell marker expression between WDLD and differentiated tumors.

Conclusions:

• This is the first biological characterization of WDLD pituitary tumors.
• WDLD tumors exhibit elevated SOX2 expression, indicating a potential role for stem cells in their pathogenesis.
• Further research is needed to elucidate the precise role of stem cells in WDLD tumor development.