Prevention of hepatocellular carcinoma by targeting MYCN-positive liver cancer stem cells with acyclic retinoid

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 19; pp. 4969 - 4974
• Main Authors: Qin, Xian-Yang, Suzuki, Harukazu, Honda, Masao, Okada, Hikari, Kaneko, Shuichi, Inoue, Ikuyo, Ebisui, Etsuko, Hashimoto, Kosuke, Carninci, Piero, Kanki, Keita, Tatsukawa, Hideki, Ishibashi, Naoto, Masaki, Takahiro, Matsuura, Tomokazu, Kagechika, Hiroyuki, Toriguchi, Kan, Hatano, Etsuro, Shirakami, Yohei, Shiota, Goshi, Shimizu, Masahito, Moriwaki, Hisataka, Kojima, Soichi
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 08-05-2018
• Subjects: Animal models; Biological Sciences; Biomarkers; Biotechnology; Cancer; Caspase; Caspase-8; Cell culture; Cell death; Flow cytometry; Functional analysis; Gene expression; Genomes; Hepatocellular carcinoma; Hepatocytes; Liver; Liver cancer; Medical prognosis; Metastases; Metastasis; Myc protein; Patients; Stem cell transplantation; Stem cells; Therapeutic applications; Transcription factors; Vitamin A; Wnt protein; β-catenin; acyclic retinoid; MYCN; cancer stem cell; transcriptome; hepatocellular carcinoma
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1802279115

Hepatocellular carcinoma (HCC) is a highly lethal cancer that has a high rate of recurrence, in part because of cancer stem cell (CSC)-dependent field cancerization. Acyclic retinoid (ACR) is a synthetic vitamin A-like compound capable of preventing the recurrence of HCC. Here, we performed a genome-wide transcriptome screen and showed that ACR selectively suppressed the expression of MYCN, a member of the MYC family of basic helix–loop–helix–zipper transcription factors, in HCC cell cultures, animal models, and liver biopsies obtained from HCC patients. MYCN expression in human HCC was correlated positively with both CSC and Wnt/β-catenin signaling markers but negatively with mature hepatocyte markers. Functional analysis showed repressed cell-cycle progression, proliferation, and colony formation, activated caspase-8, and induced cell death in HCC cells following silencing of MYCN expression. High-content single-cell imaging analysis and flow cytometric analysis identified a MYCN⁺ CSC subpopulation in the heterogeneous HCC cell cultures and showed that these cells were selectively killed by ACR. Particularly, EpCAM⁺ cells isolated using a cell-sorting system showed increased MYCN expression and sensitivity to ACR compared with EpCAM⁻ cells. In a long-term (>10 y) follow-up study of 102 patients with HCC, MYCN was expressed at higher levels in the HCC tumor region than in nontumor regions, and there was a positive correlation between MYCN expression and recurrence of de novo HCC but not metastatic HCC after curative treatment. In summary, these results suggest that MYCN serves as a prognostic biomarker and therapeutic target of ACR for liver CSCs in de novo HCC.