Ivanova Lāsma, Zandberga Elīna, Siliņa Karīna, Kalniņa Zane, Ābols Artūrs, Endzeliņš Edgars, Vendina Ineta, Romanchikova Nadezhda, Hegmane Alinta, Trapencieris Pēteris, Eglītis Jānis, Linē Aija
Latvian Biomedical Research and Study Centre, Ratsupites Str 1, Riga, 1067, Latvia.
Cancer Chemother Pharmacol. 2015 Feb;75(2):235-46. doi: 10.1007/s00280-014-2635-1. Epub 2014 Nov 25.
Carbonic anhydrase IX (CAIX) is a hypoxia-inducible enzyme with extracellular catalytic domain that is overexpressed in a variety of cancers including breast cancer and plays a crucial role in maintaining favourable intracellular pH and reducing extracellular pH. The purpose of the current study was to elucidate the prognostic significance of CAIX in the intrinsic subtypes of breast cancer and to characterise CAIX as a drug target in breast cancer.
The prognostic significance of CAIX mRNA expression was interrogated in a cohort of 3,455 breast tumours by using an online tool, Kaplan-Meier plotter. The functional effects of stable CAIX depletion by shRNA in three breast cancer cell lines—MDA-MB-231, MCF7 and SKBR-3, representing basal-like, luminal A and HER2+ subtypes, respectively—were studied by proliferation, invasion, clonal spheroid formation and chemosensitivity assays under normoxia and hypoxia. Finally, the effect of pharmacological CA inhibition alone or in the combination with doxorubicin on self-renewal was assessed by spheroid-forming assay.
High CAIX mRNA expression was significantly associated with poor survival in patients with basal-like, luminal B and triple-negative breast cancer, but not luminal A and HER+ subtypes. Silencing of CAIX expression had no significant effect on the cell proliferation or viability upon treatment with doxorubicin in any of the cell lines studied, while it inhibited spheroid formation in hypoxic conditions. Furthermore, pharmacological inhibition of CAs using acetazolamide had a synergistic effect with doxorubicin on decreasing the spheroid-forming efficiency in MDA-MB-231 cells.
Inhibition of CAIX reduces the self-renewal capacity of breast cancer cells, and the combination of doxorubicin and CAIX inhibition is an attractive therapeutic strategy in basal-like and triple-negative breast cancer, which warrants further investigations.
碳酸酐酶IX（CAIX）是一种具有细胞外催化结构域的缺氧诱导酶，在包括乳腺癌在内的多种癌症中过表达，在维持有利的细胞内pH值和降低细胞外pH值方面发挥关键作用。本研究的目的是阐明CAIX在乳腺癌内在亚型中的预后意义，并将CAIX表征为乳腺癌的药物靶点。
使用在线工具Kaplan-Meier plotter在3455例乳腺肿瘤队列中研究CAIX mRNA表达的预后意义。通过在常氧和缺氧条件下的增殖、侵袭、克隆球体形成和化学敏感性测定，研究了shRNA稳定敲低CAIX在三种乳腺癌细胞系（MDA-MB-231、MCF7和SKBR-3，分别代表基底样、腔面A型和HER2+亚型）中的功能效应。最后，通过球体形成试验评估单独或与阿霉素联合使用的药理学CA抑制对自我更新的影响。
CAIX mRNA高表达与基底样、腔面B型和三阴性乳腺癌患者的不良生存显著相关，但与腔面A型和HER+亚型无关。在所研究的任何细胞系中，用阿霉素处理后，CAIX表达的沉默对细胞增殖或活力没有显著影响，而它在缺氧条件下抑制球体形成。此外，使用乙酰唑胺对碳酸酐酶进行药理学抑制与阿霉素对降低MDA-MB-231细胞球体形成效率具有协同作用。
抑制CAIX可降低乳腺癌细胞的自我更新能力，阿霉素与CAIX抑制的联合是基底样和三阴性乳腺癌中一种有吸引力的治疗策略，值得进一步研究。
