Cathepsin B, D and K expression in adamantinomatous craniopharyngiomas relates to their levels of differentiation as determined by the patterns of retinoic acid receptor expression

Aims: To investigate the potential predictive value of cathepsins B, D and K in a series of 51 adamantinomatous craniopharyngiomas. While almost always benign, craniopharyngiomas exhibit a high propensity to recur postsurgically and biological markers are therefore needed to predict their recurrence. We have previously demonstrated the potential predictive value of retinoic acid receptors (RARs) (Lefranc et al., J. Neurosurg. 2003; 98; 145–153). Methods and results: Computer‐assisted microscopy was used to determine quantitatively the immunohistochemical levels of expression of the α, β and γ RAR subtypes and cathepsins B, D and K. The levels of expression of cathepsin D and of cathepsin B correlated significantly with the levels of expression of RARβ. The levels of expression of cathepsin K correlated significantly with the levels of expression of RARγ. Conclusions: Recurrent adamantinomatous craniopharyngiomas are characterized by low levels of RARβ and high levels of RARγ. The tendency to recurrence seems, at least partly, to relate to the fact that (i) craniopharyngiomas with low levels of RARβ express low levels of cathepsin D, and (ii) craniopharyngiomas with high levels of RARγ express high levels of cathepsin K.