Increased CYP24A1 mRNA expression after 1,25-Dihydroxyvitamin D3 treatment of hepatocellular carcinoma cell lines in vitro and also in human liver cancer

• Published in: Zeitschrift für Gastroenterologie
• Main Authors: Horvath, E, Lakatos, P, Balla, B, Kósa, PJ, Kovalszky, I, Pesti, V, Németh, D, Hasan, J, Korompay, A, Somorácz, Á, Schaff, Z, Kupcsulik, P, Szalay, F
• Format: Conference Proceeding
• Language: English; German
• Published: 06.05.2011
• ISSN: 0044-2771; 1439-7803
• DOI: 10.1055/s-0031-1278459

Background and aims: The active metabolite of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25D3) inhibits cell growth in numerous tumors as colon, prostate, breast. The role of 1,25-D3 in the development of the hepatocellular carcinoma (HCC) has not yet been established. We aimed to study the mRNA expression of vitamin D inactivating CYP24A1 enzyme in HCC cell lines after 1,25D3 treatment in vitro and also in human HCC tissue samples. Methods: HepG2 and HUHneo (Univ. Heidelberg) cells were treated with 4 nM of 1,25D3 in Optimem medium and were incubated in two parallels for duration of 30, 60, 120 minutes, 5, 8, 10, 12, 14, 24, 26, 28 hours. Human liver samples were obtained from surgically removed HCC and the surrounding not-tumor tissue. Total RNA was isolated with Roche High Pure Total RNA Isolation kit and reverse-transcribed to cDNA in both cell lines and in 12 normal liver and 17 HCC human frozen samples. The expression differences were analyzed by Taqman probe-based quantitative real-time PCR. Relative quantification was carried out from collected data by Applied Biosystems 7500 System SDS software 1.3. Results: CYP24A1 mRNA expression was significantly (p<0.001) increased in response to 1,25-D3 administration in a time-dependent manner in both cell lines. In HepG2 cell line the CYP24A1 mRNA expression showed 5300-fold elevation reaching the maximum value at 8 hours. In the HUHneo cells the increase was 152-fold of the baseline level, and the curve reached the maximum at 14 hours. The activating effect of vitamin D3 on CYP24 mRNA expression was at 28 hours still detectable. The CYP24A1 mRNS expression was higher in human HCC tissues than in surrounding non-tumor tissue (p<0.05). Conclusions: Our novel data raise the possibility that the significant increase in the CYP24A1 gene expression of hepatocellular carcinoma cell lines following vitamin D administration may stimulate the inactivation of 1,25-D3., thus „protecting“ the tumor cells against the anti-cancer effects of 1,25-D3. This is the first report on the role of vitamin D3 on the CYP24A1 mRNA transcription in hepatocellular carcinoma cells in vitro.