Related Experiment Videos
Fas/Fas ligand system and apoptosis induction in testicular carcinoma
Hans U Schmelz1, Michael Abend, Klaus Kraft
1Department of Urology, Federal Armed Forces Hospital, Ulm, Germany. hans.u.schmelz@web.de
Background:
Tumor-infiltrating, Fas ligand (FasL)-expressing lymphocytes are able to eliminate Fas-bearing tumor cells by apoptosis induction. Activated cytotoxic T-cells that express Fas may enter apoptosis in the presence of FasL tumor cells. To date, no studies of patients with testicular carcinoma have correlated the differential expression of Fas and FasL in both cell types with the corresponding apoptotic index (AI).
Methods:
Fas and FasL were investigated immunohistochemically in paraffin embedded tissue sections from 25 patients with nonseminomatous testicular tumors. The percentages of positive cells and the ratios of Fas cells to FasL cells were correlated with the AI of tumor cells and lymphocytes, respectively, using Spearman correlations.
Results:
No association was found between the rate of FasL positive cells and AI of the other cell type or between the rate of Fas positive cells and the AI of the same cell type. Ratios between Fas positive cells and FasL positive cells were not correlated with the AI; however, a significant positive correlation was found between the AI of tumor cells and the AI of lymphocytes.
Conclusions:
It seems unlikely that the Fas/FasL system is responsible for immune escape of the tumor in testicular carcinoma. Rather, the significant positive correlation between the AIs of tumor cells and lymphocytes implicate a previously unknown mechanism of apoptosis induction in both cell types.
Insights
The Fas/FasL system does not appear to drive immune escape in testicular carcinoma. A significant positive correlation between tumor cell and lymphocyte apoptosis indices suggests a novel apoptosis induction mechanism.
Area of Science:
- Immunology
- Oncology
- Cell Biology
Background:
- Tumor-infiltrating lymphocytes expressing Fas ligand (FasL) can induce apoptosis in Fas-bearing tumor cells.
- Activated cytotoxic T-cells expressing Fas may undergo apoptosis when encountering FasL-expressing tumor cells.
- Previous studies have not correlated Fas and FasL expression with apoptotic indices in testicular carcinoma.
Purpose of the Study:
- To investigate the role of the Fas/FasL system in immune escape in nonseminomatous testicular tumors.
- To correlate Fas and FasL expression with apoptotic indices in tumor cells and lymphocytes.
- To explore potential mechanisms of apoptosis induction in testicular carcinoma.
Main Methods:
- Immunohistochemistry was used to analyze Fas and FasL expression in 25 nonseminomatous testicular tumor samples.
- Quantified Fas and FasL positive cells and their ratios.
- Spearman correlation analysis was employed to assess relationships between cell expression and apoptotic indices (AI) in tumor cells and lymphocytes.
Main Results:
- No significant correlation was observed between FasL-positive cell rates and the AI of the other cell type.
- No significant correlation was found between Fas-positive cell rates and the AI of the same cell type.
- A significant positive correlation was identified between the AI of tumor cells and the AI of lymphocytes.
Conclusions:
- The Fas/FasL system is unlikely to be the primary mechanism for tumor immune escape in testicular carcinoma.
- The strong positive correlation between tumor cell and lymphocyte apoptosis indices suggests an alternative, uncharacterized apoptosis induction pathway.
- Further research is warranted to elucidate this novel mechanism of apoptosis in testicular cancer.