Abstract 2240: CK19 based molecular classification defined three distinct hepatocellular carcinoma subtypes with different cell lineage features and therapeutic vulnerabilities
Authors: Wang Qiuyan , Lu Qinchen , Wang Yaobang , Wang Zhenxing , Wang Xi , Tao Yuting , Xiang Bangde , Yang Herry 
Published: April 2023

Abstract
Purpose: CK19 has been recognized as an important molecular marker for poor prognosis of Hepatocellular carcinoma (HCC), however, its molecular determinants and clinical implications is still remains a largely unmet challenge. We sought to identify molecular features and develop a CK19-based molecular classification model to provide new strategies for precise treatment of this deadly HCC.
Experimental Design: Tumor and matched non-tumor liver specimens were collected from 116 patients who underwent partial hepatectomy for primary or recurrent HCC in Guangxi region. HCC patients were classified into two CK19 positive subtypes and one CK19 negative subtype based on CK19 related transcriptomic profiling. The tumor heterogeneity of three subtypes were further characterized by multiomics technology including whole-exome sequencing, bulk and single-cell RNA sequencing, whole genome methylation , and imaging mass cytometry (IMC). Subtype scoring were validated using the TCGA database and in vitro cell line.
Results: We innovatively constructed an accurate classification scoring system for CK19 related HCC, which divided CK19 positive HCC into “Hepatic stem cell”(K1) and “Hepatic progenitor cell”(K2) two distinct subtypes with respective pathway and clinicopathological phenotypes . K1 is characterized by poor prognosis, and activation of Myc and proliferation pathway. Meanwhile, down-regulation of p53 pathway and low differentiation are also unique characteristics of K1, Compared with K1, K2 showed enrichment of pro-oncogene Ras pathway and high expression of inflammatory signals and immune cells. Moreover, these two CK19 positive subtypes have different cell lineage gene expression and they may come from different cell lineage types. K1 may come from CK19 negative HCC by epigenetic regulation but K2 may come from hepatic progenitor cells activated by inflammatory stimulation. Specifically, we identified K1 as a new poor prognosis stem cell subtype of CK19 positive HCC. K1 highly expressed tumor stem cell markers and displayed very low expression of androgen receptor AR, as well as activation of neural related signal pathway, which is ineffective for postoperative TACE treatment.
Conclusion: These data suggest that lineage plasticity may contribute to heterogeneity of CK19 positive HCC, which in turn carry clinical implications regarding new treatment strategies for treatment of HCC with highly recurrence.
Citation Format: Qiuyan Wang, Qinchen Lu, Yaobang Wang, Zhenxing Wang, Xi Wang, Yuting Tao, Bangde Xiang, Herry Yang. CK19 based molecular classification defined three distinct hepatocellular carcinoma subtypes with different cell lineage features and therapeutic vulnerabilities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2240.