Influence of 1α, 25-dihydroxyvitamin D3 [1, 25(OH)2D3] on the expression of Sox 9 and the transient receptor potential vanilloid 5/6 ion channels in equine articular chondrocytes

Background Sox 9 is a major marker of chondrocyte differentiation. When chondrocytes are cultured in vitro they progressively de-differentiate and this is associated with a decline in Sox 9 expression. The active form of vitamin D, 1, 25 (OH)2D3 has been shown to be protective of cartilage in both humans and animals. In this study equine articular chondrocytes were grown in culture and the effects of 1, 25 (OH)2D3 upon Sox 9 expression examined. The expression of the transient receptor potential vanilloid (TRPV) ion channels 5 and 6 in equine chondrocytes in vitro, we have previously shown, is inversely correlated with de-differentiation. The expression of these channels in response to 1, 25 (OH)2D3 administration was therefore also examined. Results The active form of vitamin D (1, 25 (OH)2D3) when administered to cultured equine chondrocytes at two different concentrations significantly increased the expression of Sox 9 at both. In contrast 1, 25 (OH)2D3 had no significant effect upon the expression of either TRPV 5 or 6 at either the protein or the mRNA level. Conclusions The increased expression of Sox 9, in equine articular chondrocytes in vitro, in response to the active form of vitamin D suggests that this compound could be utilized to inhibit the progressive de-differentiation that is normally observed in these cells. It is also supportive of previous studies indicating that 1α, 25-dihydroxyvitamin D3 can have a protective effect upon cartilage in animals in vivo. The previously observed correlation between the degree of differentiation and the expression levels of TRPV 5/6 had suggested that these ion channels may have a direct involvement in, or be modulated by, the differentiation process in vitro. The data in the present study do not support this

Combining gene and immunotherapy for prostate cancer

The nitroreductase (NR)/CB1954 enzyme prodrug system has given promising results in pre-clinical studies and is currently being assessed in phase I and II clinical trials in prostate cancer. Enhanced cell killing by apparent immune-mediated mechanisms has been shown in pancreatic and colorectal cancer models, by co-expressing murine granulocyte macrophage colony-stimulating factor (GM-CSF) with NR in a single replication deficient adenoviral vector. This consists of the CMV immediate early promotor driving expression of NR, with an internal ribosome entry site (IRES) and the gene for murine GM-CSF (mGM-CSF). To examine if similar enhancement of tumour cell killing could be produced in prostate cancer, the TRAMP model was chosen. Results illustrate that the combination of suicide gene therapy using NR and CB1954, with cytokine stimulation with mGM-CSF gives an improved response compared with either modality alone. The mechanism of this improved response is however likely to be non-immune based as it lacks a memory effect