Trisomy 7 in nonneoplastic epithelial kidney cells

Area of Science:

• Genetics
• Oncology
• Nephrology

Background:

• Trisomy 7 is a common chromosomal aberration in renal cell carcinomas (RCC).
• It has been hypothesized that trisomy 7 in RCC and surrounding kidney tissue originates from tumor-infiltrating T-helper lymphocytes.

Purpose of the Study:

• To investigate the cellular origin of trisomy 7 in non-neoplastic kidney tissues.
• To determine if trisomy 7 is associated with T-lymphocytes or epithelial cells.

Main Methods:

• Cytogenetic analysis of metaphase cells.
• Fluorescence in situ hybridization (FISH) of interphase nuclei.
• Immunoenzymatic staining for T-cells (CD3) and epithelial cells (cytokeratins).

Main Results:

• FISH analysis revealed trisomy 7 frequencies ranging from 1.0-8.9% in uncultured cells and 0.4-8.6% in cultured cells.
• Cytogenetic analysis showed trisomy 7 frequencies of 1.0-19.0% after one week of culture.
• T-cell frequencies were 2.9-10% in uncultured and primary cultures, decreasing to <1% with extended culture.
• Combined FISH and immunostaining demonstrated that cells with trisomy 7 were predominantly epithelial cells (0-5% T-lymphocytes).

Conclusions:

• Trisomy 7 in non-neoplastic kidney tissue is mainly found in epithelial cells.
• The previous hypothesis linking trisomy 7 in RCC to T-helper lymphocytes is unlikely.
• These findings necessitate a re-evaluation of the significance of trisomy 7 in renal neoplasia.