• Bcl-x(L) expression in vivo in rheumatoid synovium.

      Busteed, S; Bennett, M W; Molloy, C; Houston, A; Stone, M A; Shanahan, F; Molloy, M G; O'Connell, J; Department of Medicine, Cork University Hospital, National University of Ireland,, Wilton, Cork, Ireland. sandra_busteed@hotmail.com (2012-02-03)
      To examine the expression of the apoptosis regulatory protein, Bcl-x(L), in the synovium of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Immunohistochemistry for Bcl-x(L) was carried out on synovial samples from patients with RA and OA. Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis were performed to qualitatively examine the expression of Bcl-x(L). Bcl-x(L) expression was detected in the lining, endothelium and inflammatory cells of both RA (n=20) and OA (n=10) samples. However, there was significantly more expression in the lining of RA synovium compared to OA (77 vs 61%, p<0.05). Many of the positive cells in the RA subsynovium were noted to be plasma cells. There was a significant correlation between Bcl-x(L) expression and the number of inflammatory cells in the subsynovium of RA and OA patients (r (s)=0.376, p<0.05, n=30). Age and disease duration did not correlate with Bcl-x(L) expression in rheumatoid patients. Bcl-x(L) may play a role in the extended survival of synoviocytes and inflammatory cells in rheumatoid synovium.
    • Prostaglandin E2 stimulates Fas ligand expression via the EP1 receptor in colon cancer cells.

      O'Callaghan, G; Kelly, J; Shanahan, F; Houston, A; Department of Medicine, University College Cork, National University of Ireland, , Clinical Science Building, Cork University Hospital, Wilton, Cork, Ireland. (2012-02-03)
      Fas ligand (FasL/CD95L) is a member of the tumour necrosis factor superfamily that triggers apoptosis following crosslinking of the Fas receptor. Despite studies strongly implicating tumour-expressed FasL as a major inhibitor of the anti-tumour immune response, little is known about the mechanisms that regulate FasL expression in tumours. In this study, we show that the cyclooxygenase (COX) signalling pathway, and in particular prostaglandin E(2) (PGE(2)), plays a role in the upregulation of FasL expression in colon cancer. Suppression of either COX-2 or COX-1 by RNA interference in HCA-7 and HT29 colon tumour cells reduced FasL expression at both the mRNA and protein level. Conversely, stimulation with PGE(2) increased FasL expression and these cells showed increased cytotoxicity against Fas-sensitive Jurkat T cells. Prostaglandin E(2)-induced FasL expression was mediated by signalling via the EP1 receptor. Moreover, immunohistochemical analysis using serial sections of human colon adenocarcinomas revealed a strong positive correlation between COX-2 and FasL (r=0.722; P<0.0001) expression, and between EP1 receptor and FasL (r=0.740; P<0.0001) expression, in the tumour cells. Thus, these findings indicate that PGE(2) positively regulates FasL expression in colon tumour cells, adding another pro-neoplastic activity to PGE(2).