Lack Of Fas Expression Research Articles

Regulators of Apoptosis in Cholangiocarcinoma

Dysregulation of mediators of apoptosis is associated with carcinogenesis. For biliary duct cancers, p53 gene mutation is an important contributor to carcinogenesis. Mutations in the p53 gene affect transcription of the Fas gene, resulting in lack of Fas expression on cell membrane. It has been previously shown that cloned Fas-negative but not Fas-positive human cholangiocarcinoma cells are resistant to anti-Fas-mediated apoptosis and develop tumors in nude mice. In addition, interferon gamma induces Fas expression in Fas-negative cholangiocarcinoma cells and makes them susceptible to apoptosis. Therefore, it becomes important to characterize immunophenotypic expression of p53 and Fas in normal and neoplastic human tissues of the biliary tract to further understand the pathogenesis of the disease. To date, human studies to characterize differences in immunophenotypic expression of the Fas protein between intrahepatic and extrahepatic biliary duct cancers and in their precursor lesions have not been performed. To report the immunophenotypic expression of p53 and Fas expression in various stages in the development of bile duct cancers (intrahepatic and extrahepatic tumor location) and their association with tumor differentiation. Thirty bile duct cancer samples (13 intrahepatic and 17 extrahepatic) from 18 men and 12 women who ranged in age from 44 to 77 years (mean age, 65.6 years) were retrieved from the surgical pathology files. Hematoxylin-eosin-stained slides were evaluated for the type and grade of tumor and dysplastic changes in the biliary tract epithelium. Additional slides were immunohistochemically stained with p53 and anti-Fas mouse monoclonal antibody. The pattern of Fas distribution and percentage of cells positive for p53 and Fas expression were determined. The percentage of Fas-expressing cells is significantly (P = .01) more frequently noted in extrahepatic tumors compared with intrahepatic tumors. Furthermore, Fas expression decreased from dysplastic epithelium to cholangiocarcinoma (P = .01), and this decreasing trend continued from well to poorly differentiated tumors. Nuclear p53 expression was not identified in normal and dysplastic epithelium but was noted in 30% of carcinomas (P = .02). Fas expression is an early event in pathogenesis of bile duct cancers. Immunophenotypic expression of Fas is associated with well to moderately differentiated tumors but not with poor tumor differentiation.

The Expression of Fas Antigen (CD 95) on Clonogenic Acute Myeloid Leukemia Cells Correlates with Their In Vitro Sensitivity to Farnesyltransferase Inhibitor (FTI; Zarnestra TM).

The farnesyl transferase inhibitors (FTIs) have demonstrated significant antitumor activities in vitro and in vivo due to their ability to inhibit of Ras- oncogen farnesylation. Besides Ras, there are many other farnesylated proteins in cancer pathways which are potential targets for FTI. In this study, the in vitro effect of the FTI (Zarnestra, Z: provided kindly by Johnson & Johnson Pharmaceutical Research and Development) on clonogenic leukemia cells, expressing CD 34 and Fas were examined. All evaluated patients fullfilled the diagnostic criteria for high-risk AML and demonstrated the CFU-L in vitro growth, or/and expression of CD34 antigen on the myeloblast cells. Bone marrow mononuclear cells from 30 AML patients (M0=3, M1=15, M2=5, M3=1, M4=5, M5=1) were isolated and were plated in serum-free methylcellulose medium with or without growth factors (Methocult, Stem Cell Technologies, Vancouver, Canada) for the 14 days in vitro cultures. The expression of Fas (CD 95) on AML cells were also studied (anti-Fas APO-1, FITC- CD 95, Becton Dickinson, USA) by flow cytometric analysis using Cell Quest Software (Becton Dickinson, USA). MNC incubated with increasing concentrations of Z for 24, 48 and 72 days were analysed for apoptosis (staining for annexin-possitive cells, Annexin V Kit, Pharmingen, USA).The percentage of Fas positivity was variable (range 20–94%) and was related to the morphologic FAB classification with the highest expression in AML-M1 patients (range 28–94, mean 72%, p<0.01).. No relationship was found between Fas and the CD 34 antigen expression. The in vitro CFU-L growth in the presence of cytokines was observed in 19/30 patients (63%) and 37% patients showed the spontaneous CFU-L or no colony growth of blast cells in the in vitro culture. In the majority of evaluated AML cases, a time and dose dependent proapoptotic in vitro effect of Z was found. The above effect was the most frequent in AML-M1 patients (11/23). Within Z concentration between 20–300 nM, the significant increase of apoptosis cell number (mean 60% AN+/PI− cells) was observed. After 24, 48 and 72 h, incubation with Z the number of patients whose cells underwent apoptosis were 49%, 13% and 8% respectively. The Z induced apoptosis showed significant correlation with Fas expression on AML cells.(P<0.01). The myeloblast apoptotic was not detected in the patients (40 %) demonstrated spontaneous CFU-L growth and the lack of Fas expression on blast cells (even after 120 h Z. exposure).Our observations suggest that Z induced apoptosis of AML cells might be mediated at least in part by Fas, expressed on primitive, clonogenic leukemic progenitor cells. Induction of apoptosis throught the Fas pathway might be one of the new approach for effective leukemia therapy.

Expression of Fas and Fas-ligand in primary cutaneous T-cell lymphoma (CTCL): association between lack of Fas expression and aggressive types of CTCL.

Fas (CD95; APO-1) is a transmembrane protein that mediates apoptosis upon cross-linking with Fas-ligand (Fas-L). Interaction of Fas-L expressed by cytotoxic T cells with Fas-expressing tumour cells plays an important part in antitumour immune responses. We aimed to investigate Fas and Fas-L expression in frozen and paraffin-embedded material from a large group of patients with cutaneous T-cell lymphoma (CTCL). Immunostaining with monoclonal antibodies against Fas and Fas-L was performed in material from 23 patients with mycosis fungoides (MF), 10 with lymphomatoid papulosis (LyP), 10 with CD30-positive primary cutaneous large T-cell lymphoma (LTCL) and nine with CD30-negative LTCL. The results were correlated with the type and stage of CTCL and clinical features. Expression of Fas by the large majority of the neoplastic T cells was observed in 15 of 15 cases of plaque-stage MF, 10 of 10 cases of LyP and 10 of 10 cases of CD30-positive LTCL, but only in four of 12 cases of tumour-stage MF and two of nine cases of CD30-negative LTCL. In three of four MF patients in whom both plaques and tumours could be studied, a significant decrease in Fas expression was observed with progression from plaque-stage to tumour-stage disease. Fas-L was expressed by > 50% of the neoplastic T cells in 46 of 56 biopsies, and no clear relationship with type of CTCL and clinical behaviour was observed. This study demonstrates loss of Fas expression in aggressive types of CTCL, but not in indolent types of CTCL. These data suggest that loss of Fas receptor expression may be one of the mechanisms that allow tumour cells to escape an effective immune response, and may contribute to the unfavourable prognosis of some types of CTCL.