Dysregulated Expression of MITF in Subsets of Hepatocellular Carcinoma and Cholangiocarcinoma

Dysregulated Expression of MITF in Subsets of Hepatocellular Carcinoma and Cholangiocarcinoma

NATTAKARN NOORON,^1,2 KOJI OHBA,¹ KAZUHISA TAKEDA,¹ SHIGEKI SHIBAHARA^1,3 and ANCHALEE CHIABCHALARD²

¹Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai, Miyagi, Japan
²Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
³Faculty of Sports Science, Sendai University, Shibata-gun, Miyagi, Japan

Cholangiocarcinoma represents the second most common primary liver tumor after hepatocellular carcinoma. Mahanine, a carbazole alkaloid derived from Murraya koenigii (Linn.) Spreng, has been used as folk medicine in Thailand, where the liver fluke-associated cholangiocarcinoma is common. The expression of microphthalmia-associated transcription factor (MITF) is maintained at immunohistochemically undetectable levels in hepatocytes and cholangiocytes. To explore the regulation of MITF expression in the liver, we immunohistochemically analyzed the MITF expression using hepatocellular carcinoma and cholangiocarcinoma specimens of the human liver cancer tissue array. MITF immunoreactivity was detected in subsets of hepatocellular carcinoma (6 out of 38 specimens; 16%) and cholangiocarcinoma (2/7 specimens; 29%). Moreover, immunoreactivity for glioma-associated oncogene 1 (GLI1), a transcription factor of the Hedgehog signaling pathway, was detected in 55% of hepatocellular carcinoma (21/38 specimens) and 86% of cholangiocarcinoma (6/7 specimens). Importantly, MITF was detectable only in the GLI1-positive hepatocellular carcinoma and cholangiocarcinoma, and MITF immunoreactivity is associated with poor prognosis in patients with hepatocellular carcinoma. Subsequently, the effect of mahanine was analyzed in HepG2 human hepatocellular carcinoma and HuCCT1 and KKU-100 human cholangiocarcinoma cells. Mahanine (25 μM) showed the potent cytotoxicity in these hepatic cancer cell lines, which was associated with increased expression levels of MITF, as judged by Western blot analysis. MITF is over-expressed in subsets of hepatocellular carcinoma and cholangiocarcinoma, and detectable MITF immunoreactivity is associated with poor prognosis in patients with hepatocellular carcinoma. MITF expression levels may be determined in hepatic cancer cells by the balance between the Hedgehog signaling and the cellular stress.

keywords —— cholangiocarcinoma; GLI1; Hedgehog signaling; hepatocellular carcinoma; mahanine

===============================

Tohoku J. Exp. Med., 2017, 242, 291-302

Correspondence: Anchalee Chiabchalard, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand.

e-mail: Anchalee.c@chula.ac.th