Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark.
Department of Surgery, Randers Regional Hospital, Randers, Denmark.
Breast Cancer Res. 2023 Apr 25;25(1):46. doi: 10.1186/s13058-023-01644-1.
Carbonic anhydrases catalyze CO/HCO buffer reactions with implications for effective H mobility, pH dynamics, and cellular acid-base sensing. Yet, the integrated consequences of carbonic anhydrases for cancer and stromal cell functions, their interactions, and patient prognosis are not yet clear.
We combine (a) bioinformatic analyses of human proteomic data and bulk and single-cell transcriptomic data coupled to clinicopathologic and prognostic information; (b) ex vivo experimental studies of gene expression in breast tissue based on quantitative reverse transcription and polymerase chain reactions, intracellular and extracellular pH recordings based on fluorescence confocal microscopy, and immunohistochemical protein identification in human and murine breast cancer biopsies; and (c) in vivo tumor size measurements, pH-sensitive microelectrode recordings, and microdialysis-based metabolite analyses in mice with experimentally induced breast carcinomas.
Carbonic anhydrases-particularly the extracellular isoforms CA4, CA6, CA9, CA12, and CA14-undergo potent expression changes during human and murine breast carcinogenesis. In patients with basal-like/triple-negative breast cancer, elevated expression of the extracellular carbonic anhydrases negatively predicts survival, whereas, surprisingly, the extracellular carbonic anhydrases positively predict patient survival in HER2/ErbB2-enriched breast cancer. Carbonic anhydrase inhibition attenuates cellular net acid extrusion and extracellular H elimination from diffusion-restricted to peripheral and well-perfused regions of human and murine breast cancer tissue. Supplied in vivo, the carbonic anhydrase inhibitor acetazolamide acidifies the microenvironment of ErbB2-induced murine breast carcinomas, limits tumor immune infiltration (CD3 T cells, CD19 B cells, F4/80 macrophages), lowers inflammatory cytokine (Il1a, Il1b, Il6) and transcription factor (Nfkb1) expression, and accelerates tumor growth. Supporting the immunomodulatory influences of carbonic anhydrases, patient survival benefits associated with high extracellular carbonic anhydrase expression in HER2-enriched breast carcinomas depend on the tumor inflammatory profile. Acetazolamide lowers lactate levels in breast tissue and blood without influencing breast tumor perfusion, suggesting that carbonic anhydrase inhibition lowers fermentative glycolysis.
We conclude that carbonic anhydrases (a) elevate pH in breast carcinomas by accelerating net H elimination from cancer cells and across the interstitial space and (b) raise immune infiltration and inflammation in ErbB2/HER2-driven breast carcinomas, restricting tumor growth and improving patient survival.
碳酸酐酶催化 CO/HCO 缓冲反应，对有效 H 迁移、pH 动力学和细胞酸碱感应具有重要意义。然而，碳酸酐酶对癌症和基质细胞功能的综合影响、它们之间的相互作用以及患者的预后尚不清楚。
我们结合了（a）对人类蛋白质组学数据的生物信息学分析，以及与临床病理和预后信息相结合的批量和单细胞转录组学数据；（b）基于定量逆转录聚合酶链反应的乳腺组织基因表达的离体实验研究、基于荧光共焦显微镜的细胞内和细胞外 pH 记录，以及人乳腺癌活检中免疫组织化学蛋白鉴定；以及（c）在实验诱导的乳腺癌小鼠中进行肿瘤大小测量、pH 敏感微电极记录和基于微透析的代谢物分析。
碳酸酐酶——特别是细胞外同工酶 CA4、CA6、CA9、CA12 和 CA14——在人类和小鼠乳腺癌发生过程中经历了强烈的表达变化。在基底样/三阴性乳腺癌患者中，细胞外碳酸酐酶的高表达预示着生存不良，而令人惊讶的是，细胞外碳酸酐酶在 HER2/ErbB2 富集型乳腺癌中预示着患者的生存良好。碳酸酐酶抑制可减弱细胞净酸外排，并从扩散受限的人类和小鼠乳腺癌组织的周边和灌注良好的区域中消除细胞外 H。体内给予碳酸酐酶抑制剂乙酰唑胺可使 ErbB2 诱导的小鼠乳腺癌的微环境酸化，限制肿瘤免疫浸润（CD3 T 细胞、CD19 B 细胞、F4/80 巨噬细胞），降低炎症细胞因子（Il1a、Il1b、Il6）和转录因子（Nfkb1）的表达，并加速肿瘤生长。支持碳酸酐酶的免疫调节影响，与 HER2 富集型乳腺癌中外源性碳酸酐酶高表达相关的患者生存获益取决于肿瘤的炎症特征。乙酰唑胺可降低乳腺组织和血液中的乳酸水平，而不影响乳腺肿瘤灌注，表明碳酸酐酶抑制可降低发酵性糖酵解。
我们得出结论，碳酸酐酶（a）通过加速癌细胞和细胞间隙的 net H 消除来提高乳腺癌中的 pH 值，以及（b）提高 ErbB2/HER2 驱动的乳腺癌中的免疫浸润和炎症，限制肿瘤生长并改善患者的生存。
