AbstractMultidrug resistance is a major challenge in clinical cancer therapy. In particular, overexpression of certain ATP‐binding cassette (ABC) transporter proteins, like the efflux transporter ABCG2, also known as breast cancer resistance protein (BCRP), has been associated with the development of resistance to applied chemotherapeutic agents in cancer therapies, and therefore targeted inhibition of BCRP‐mediated transport might lead to reversal of this (multidrug) resistance (MDR). In a previous study, we have described the introduction of a boron‐carbon cluster, namely closo‐dicarbadodecaborane or carborane, as an inorganic pharmacophore into a polymethoxylated 2‐phenylquinazolin‐4‐amine backbone. In this work, the scope was extended to the corresponding amide derivatives. As most of the amide derivatives suffered from poor solubility, only the amide derivative QCe and the two amine derivatives DMQCc and DMQCd were further investigated. Carboranes are often considered as sterically demanding phenyl mimetics or isosteres. Therefore, the organic phenyl and sterically demanding adamantyl analogues of the most promising carborane derivatives were also investigated. The studies showed that the previously described DMQCd, a penta‐methoxylated N‐carboranyl‐2‐phenylquinazolin‐4‐amine, was by far superior to its organic analogues in terms of cytotoxicity, inhibition of the human ABCG2 transporter, as well as the ability to reverse BCRP‐mediated mitoxantrone resistance in MDCKII‐hABCG2 and HT29 colon cancer cells. Our results indicate that DMQCd is a promising candidate for further in vitro as well as in vivo studies in combination therapy for ABCG2‐overexpressing cancers.
摘要多药耐药性是临床癌症治疗的一大挑战。特别是某些ATP结合盒(ABC)转运蛋白的过度表达,如外排转运蛋白ABCG2(又称乳腺癌耐药蛋白(BCRP)),与癌症治疗中化疗药物耐药性的产生有关,因此靶向抑制BCRP介导的转运可能会导致这种(多药)耐药性(MDR)的逆转。在之前的一项研究中,我们介绍了在聚甲氧基化的 2-苯基喹唑啉-4-胺骨架中引入硼碳簇,即闭合二碳化十二硼烷或碳硼烷,作为无机药基。在这项工作中,研究范围扩展到了相应的酰胺衍生物。由于大多数酰胺衍生物的溶解性较差,只有酰胺衍生物 QCe 和两种胺衍生物 DMQCc 和 DMQCd 得到了进一步研究。硼烷通常被认为是对立体要求较高的苯基模拟物或异构体。因此,我们还研究了最有前途的碳硼烷衍生物的有机苯基和立体要求苛刻的金刚烷基类似物。研究表明,之前描述的五甲氧基化 N-硼烷基-2-苯基喹唑啉-4-胺 DMQCd 在细胞毒性、抑制人类 ABCG2 转运体以及逆转 BCRP 介导的米托蒽醌在 MDCKII-hABCG2 和 HT29 结肠癌细胞中的抗药性方面远远优于其有机类似物。我们的研究结果表明,DMQCd是一种很有希望的候选药物,可用于进一步的体外和体内研究,以联合治疗ABCG2表达缺失的癌症。