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Fas ligand is expressed in normal skin and in some cutaneous malignancies
1Department of Pathology, Catholic University Medical College, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea; Cancer Research Institute, Catholic University Medical College, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea.
Abstract:
Fas, a cell surface receptor and member of the tumour necrosis factor receptor superfamily, induces apoptosis upon oligomerization by its ligand (Fas ligand: FasL). Detailed studies have revealed that Fas is broadly expressed in normal human tissues, but relatively little is known about the range of cell types capable of expressing FasL. The aim of this study was to determine the in vivo patterns of expression of Fas and FasL in human skin tissues. Immunohistochemistry was performed using paraffin-embedded samples of normal and neoplastic skin tissues. In normal skin, FasL was expressed in the epidermis, sebaceous glands, sweat glands and outer root sheath of the hair. In squamous cell carcinomas (SCC), all cases analysed expressed FasL at high levels, whereas 60% of basal cell carcinomas (BCC) were positive for FasL. Expression of Fas in normal skin was observed in the basal and spinous layers of the epidermis, the outer root sheath of the hair, and the sebaceous glands. Expression of Fas was observed in all the SCC tested and none of the BCC tested. Expression of FasL by normal cells and tumour cells in skin tissue, demonstrated for the first time in the present study, may provide an important clue to understanding skin physiology, and immune evasion of skin tumours.
Insights
This study reveals Fas ligand (FasL) expression in normal skin cells and various skin tumors. This finding offers insights into skin physiology and how skin tumors evade immune detection.
Area of Science:
- Immunology
- Dermatology
- Cell Biology
Background:
- Fas receptor triggers apoptosis upon binding its ligand, FasL.
- Fas is widely expressed in human tissues, but FasL expression patterns are less understood.
- Investigating Fas and FasL in skin is crucial for understanding skin immunity and tumor biology.
Purpose of the Study:
- To determine the in vivo expression patterns of Fas and FasL in human skin.
- To compare Fas and FasL expression in normal skin versus neoplastic skin tissues.
- To explore the implications of FasL expression in skin physiology and tumor immune evasion.
Main Methods:
- Immunohistochemistry was utilized on paraffin-embedded human skin samples.
- Samples included normal skin, squamous cell carcinomas (SCC), and basal cell carcinomas (BCC).
- Antibodies specific to Fas and FasL were used for detection.
Main Results:
- In normal skin, FasL was detected in the epidermis, sebaceous glands, sweat glands, and hair outer root sheath.
- All analyzed SCC samples showed high FasL expression; 60% of BCC samples were positive for FasL.
- Fas expression was present in normal skin epidermis, hair outer root sheath, and sebaceous glands, and in all SCCs, but not in BCCs.
Conclusions:
- This study demonstrates FasL expression in both normal skin cells and various skin tumor cells.
- The findings suggest FasL plays a role in skin physiology and immune evasion strategies employed by skin tumors.
- Further research into Fas/FasL interactions in the skin could elucidate mechanisms of skin homeostasis and cancer progression.