Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Institute of Medical Photonics, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, China.
Department of Urology, Peking University First Hospital, Beijing, 100034, China.
EBioMedicine. 2024 May;103:105070. doi: 10.1016/j.ebiom.2024.105070. Epub 2024 Apr 1.
Cholesteryl ester (CE) accumulation in intracellular lipid droplets (LDs) is an essential signature of clear cell renal cell carcinoma (ccRCC), but its molecular mechanism and pathological significance remain elusive.
Enabled by the label-free Raman spectromicroscopy, which integrated stimulated Raman scattering microscopy with confocal Raman spectroscopy on the same platform, we quantitatively analyzed LD distribution and composition at the single cell level in intact ccRCC cell and tissue specimens in situ without any processing or exogenous labeling. Since we found that commonly used ccRCC cell lines actually did not show the CE-rich signature, primary cancer cells were isolated from human tissues to retain the lipid signature of ccRCC with CE level as high as the original tissue, which offers a preferable cell model for the study of cholesterol metabolism in ccRCC. Moreover, we established a patient-derived xenograft (PDX) mouse model that retained the CE-rich phenotype of human ccRCC.
Surprisingly, our results revealed that CE accumulation was induced by tumor suppressor VHL mutation, the most common mutation of ccRCC. Moreover, VHL mutation was found to promote CE accumulation by upregulating HIFα and subsequent PI3K/AKT/mTOR/SREBPs pathway. Inspiringly, inhibition of cholesterol esterification remarkably suppressed ccRCC aggressiveness in vitro and in vivo with negligible toxicity, through the reduced membrane cholesterol-mediated downregulations of integrin and MAPK signaling pathways.
Collectively, our study improves current understanding of the role of CE accumulation in ccRCC and opens up new opportunities for treatment.
This work was supported by National Natural Science Foundation of China (No. U23B2046 and No. 62027824), National Key R&D Program of China (No. 2023YFC2415500), Fundamental Research Funds for the Central Universities (No. YWF-22-L-547), PKU-Baidu Fund (No. 2020BD033), Peking University First Hospital Scientific and Technological Achievement Transformation Incubation Guidance Fund (No. 2022CX02), and Beijing Municipal Health Commission (No. 2020-2Z-40713).
细胞内脂滴（LDs）中的胆固醇酯（CE）积累是透明细胞肾细胞癌（ccRCC）的一个重要特征，但它的分子机制和病理意义仍不清楚。
通过无标记的喇曼光谱显微镜，该显微镜在同一平台上将受激喇曼散射显微镜与共聚焦喇曼光谱相结合，我们在不进行任何处理或外源标记的情况下，原位定量分析了完整的 ccRCC 细胞和组织标本中单细胞水平的 LD 分布和组成。由于我们发现常用的 ccRCC 细胞系实际上并不具有富含 CE 的特征，因此从人组织中分离出原代癌细胞，以保留与原始组织一样高的 CE 水平的 ccRCC 脂质特征，这为研究 ccRCC 中的胆固醇代谢提供了一个更好的细胞模型。此外，我们建立了一个保留人 ccRCC 富含 CE 表型的患者来源异种移植（PDX）小鼠模型。
令人惊讶的是，我们的结果表明，CE 积累是由肿瘤抑制因子 VHL 突变诱导的，VHL 突变是 ccRCC 最常见的突变。此外，VHL 突变通过上调 HIFα 及其后续的 PI3K/AKT/mTOR/SREBPs 通路促进 CE 积累。令人鼓舞的是，胆固醇酯化的抑制显著抑制了 ccRCC 在体外和体内的侵袭性，而且毒性可忽略不计，这是通过降低膜胆固醇介导的整合素和 MAPK 信号通路的下调实现的。
总的来说，我们的研究提高了对 CE 积累在 ccRCC 中的作用的认识，并为治疗提供了新的机会。
这项工作得到了国家自然科学基金（No. U23B2046 和 No. 62027824）、国家重点研发计划（No. 2023YFC2415500）、中央高校基本科研业务费（No. YWF-22-L-547）、PKU-Baidu 基金（No. 2020BD033）、北京大学第一医院科技成果转化孵化引导基金（No. 2022CX02）和北京市卫生健康委员会（No. 2020-2Z-40713）的支持。
