GPNMB+Gal-3+ Hepatic Parenchymal Cells Promote Immunosuppressive Microenvironment Formation and Hepatocellular Carcinogenesis

Hepatocellular carcinoma (HCC) involves a multistep pathological process in which heterogenous cells are evolved to shape an immunosuppressive microenvironment. Yet it remains largely unknown regarding the specific cell populations and their evolving routes essential for HCC development. Here, we created a rat model mimicking human HCC and generated a single-cell resolution atlas to HCC development. Specifically, we identified three populations of hepatic parenchymal cells during HCC progression, i.e., metabolic hepatocyte (HC Meta ), hepatic progenitor cell-like population with differentiation potential (HPC-like Diff ) and immunosuppressive malignant transformation subset (H-M Immu ). These three distinct subpopulations formed an oncogenic trajectory depicting a dynamic landscape of hepatocyte carcinogenesis, with signature genes reflecting the transition from HPC-like Diff to H-M Immu . Cross-species comparative analysis further revealed the H-M Immu subset to be highly conserved. Importantly, the H-M Immu (GPNMB + Gal-3 + ) cells exhibit both malignant and immunosuppressive properties. Moreover, SOX18 was found to be required for the generation of GPNMB + Gal-3 + H-M Immu cells and for their ability to form tumors. Enrichment of GPNMB + Gal-3 + H-M Immu subset was found to be associated with poor prognosis and higher rate of recurrence for HCC patients. Collectively, we unraveled the single-cell evolving mechanism of HCC and uncovered GPNMB + Gal-3 + H-M Immu cells as a major subset contributing to the immunosuppressive microenvironment and HCC malignance肝细胞癌（Hepatocellular carcinoma, HCC）是一类多阶段病理过程，异质性细胞在该过程中逐步演化，最终形成免疫抑制性肿瘤微环境。然而，目前针对HCC发生发展所必需的特定细胞群及其演化路径仍知之甚少。本研究构建了模拟人类HCC的大鼠模型，并生成了覆盖HCC发生发展全过程的单细胞分辨率细胞图谱。具体而言，我们在HCC进展过程中鉴定出三类肝实质细胞亚群：代谢肝细胞（metabolic hepatocyte, HC Meta）、拥有分化潜能的肝祖细胞样群体（hepatic progenitor cell-like population with differentiation potential, HPC-like Diff）以及免疫抑制性恶性转化亚群（immunosuppressive malignant transformation subset, H-M Immu）。这三类独特的亚群共同构成一条致癌演化轨迹，刻画了肝细胞癌变的动态景观，其特征基因可反映从HPC-like Diff向H-M Immu的细胞转化过程。跨物种比较分析进一步证实，H-M Immu亚群具有高度保守性。值得关注的是，GPNMB+Gal-3+的H-M Immu细胞同时兼具恶性增殖与免疫抑制双重特性。此外，研究发现SOX18对于GPNMB+Gal-3+ H-M Immu细胞的生成及其成瘤能力均不可或缺。临床相关性分析显示，GPNMB+Gal-3+ H-M Immu亚群的富集与HCC患者的不良预后及更高复发率显著相关。综上，本研究阐明了HCC的单细胞演化机制，并揭示GPNMB+Gal-3+ H-M Immu细胞是促成免疫抑制性肿瘤微环境与HCC恶性进展的核心亚群。