Endocrine Abstracts (2010) 22 P52

Expression of mTOR and IGF2 and in vitro effects of mTOR inhibitor drugs on cell proliferation and cortisol production in human adrenocortical cancer cells

Maria Cristina De Martino1, P M van Koetsveld1, D M Sprij-Mooij1, Richard A Feelders1, Wouter W de Herder1, Steven W J Lamberts1, Annamaria Colao2, Rosario Pivonello2 & Leo J Hofland1

1Erasmus MC, Rotterdam, The Netherlands; 2Federico II University, Naples, Italy.

Background: Adrenocortical carcinoma (ACC) is an uncommon malignancy with a still scantily understood pathogenesis and generally poor prognosis. Many patients with ACC need new treatment options. mTOR inhibitors, as sirolimus (S) and temsirolimus (T), are promising antineoplastic drugs in several kinds of tumors.

Methods: In three human ACC cell lines (H295, HAC15 and SW13), we evaluated the mTOR and IGF2 expression at mRNA level (by qPCR) and at protein level by immunohistochemistry (IHC) in AgarCyto cell blocks and we tested the dose- and time-dependent effects of S and T on cell growth by the analysis of DNA-measurement. In HAC15 cells we have measured the effects of compounds on cortisol production.

Results: The IGF2 mRNA levels expression in H295 and HAC15 cells were high, whereas very low in SW13. In the three cell lines, no significant differences have been found in the mRNA expression levels of mTOR.

The IHC for IGF2 showed a very strong protein expression in H295 and HAC15 and a very low expression in SW13. However, the IHC for mTOR showed a strong positivity in all three cell types.

S and T were able to suppress the cell growth in all cell lines, in a dose- and time-dependent manner. SW13 (IC≅10−10; maximum effect >90% at the dose 10−8) was significantly more sensitive to these treatment than H295 (IC50≅10−8; maximum effect ≅50% at the dose 10−5) and HAC15 (IC50≅10−8; maximum effect ≅50% at the dose 10−5). In HAC15 6 days of treatment with S or T induced a significant inhibition of cortisol production, corrected for cell number, suggesting a direct effects of the compounds on hormonal synthesis.

Conclusion: The results of the current study demonstrated that sirolimus and temsirolimus inhibit the in vitro proliferation and cortisol production of ACC cell lines, suggesting that mTOR-inhibitors drugs may have a role in the treatment of ACC.