MECHANISMS OF RESISTANCE TO AZOLE ANTIFUNGAL AGENTS IN CANDIDA-ALBICANS ISOLATES FROM AIDS PATIENTS INVOLVE SPECIFIC MULTIDRUG TRANSPORTERS
MECHANISMS OF RESISTANCE TO AZOLE ANTIFUNGAL AGENTS IN CANDIDA-ALBICANS ISOLATES FROM AIDS PATIENTS INVOLVE SPECIFIC MULTIDRUG TRANSPORTERS
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DOI：
10.1128/aac.39.11.2378
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发表时间：
1995-11-01
影响因子：
4.9
通讯作者：
BILLE, J
中科院分区：
文献类型：
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作者：
SANGLARD, D;KUCHLER, K;BILLE, J
唑类抗真菌药物，特别是氟康唑已被广泛用于治疗艾滋病患者的口咽念珠菌病，但临床上对氟康唑的耐药病例越来越多，而且往往与体外耐药有关。为了从分子水平研究临床分离的白色念珠菌对唑类抗真菌药物的耐药机制，我们重点研究了与唑类药物细胞靶标相关的耐药机制，即细胞色素P450(14 DM)(14 DM)和调节氟康唑转运或蓄积的机制。对5株对氟康唑耐药水平不断提高的同基因白念珠菌序列的分析表明，编码14 DM I基因的过度表达或基因扩增或基因失控不是这些临床分离株耐药的主要原因。然而，我们发现对氟康唑耐药的白色念珠菌分离株不能积累H-3标记的氟康唑。在耐药细胞中，这一现象通过用叠氮抑制细胞能量供应而被逆转，这表明耐药性可能由需要能量的外排泵介导，例如那些被描述为ATP结合盒(ABC)多药转运体的细胞。事实上，一些但不是所有对氟康唑耐药的临床白色念珠菌菌株最近克隆的ABC转运体基因CDR1的mRNA水平相对增加了10倍。在一种不过度表达CDR1的耐唑白色念珠菌分离株中，另一种名为Ben(R)的外排泵的基因大量过度表达。该基因是从白色念珠菌中克隆的，用于酿酒酵母对苯菌灵的抗性。因此，至少这两个基因的过度表达或解除调控可能介导了白念珠菌对唑类药物的耐药性，即艾滋病患者口咽念珠菌病的临床分离株。ABC转运蛋白在唑类耐药中的作用进一步得到证实，缺乏多药转运蛋白的酿酒酵母突变株对包括氟康唑、伊曲康唑和酮康唑在内的唑衍生物具有超敏性。
Azole antifungal agents, and especially fluconazole, have been used widely to treat oropharyngeal candidiasis in patients with AIDS, An increasing number of cases of clinical resistance against fluconazole, often correlating with in vitro resistance, have been reported. To investigate the mechanisms of resistance toward azole antifungal agents at the molecular level in clinical C. albicans isolates, we focused on resistance mechanisms related to the cellular target of azoles, i.e., cytochrome P450(14DM) (14DM) and those regulating the transport or accumulation of fluconazole. The analysis of sequential isogenic C. albicans isolates with increasing levels of resistance to fluconazole from five AIDS patients showed that overexpression of the gene encoding 14DM I either by gene amplification or by gene deregulation was not the major cause of resistance among these clinical isolates. We found, however, that fluconazole-resistant C. albicans isolates failed to accumulate H-3-labelled fluconazole. This phenomenon was reversed in resistant cells by inhibiting the cellular energy supply with azide, suggesting that resistance could be mediated by energy-requiring efflux pumps such as those described as ATP-binding cassette (ABC) multidrug transporters, In fact, some but not all fluconazole-resistant clinical C. albicans isolates exhibited up to a 10-fold relative increase in mRNA levels for a recently cloned ABC transporter gene called CDR1. In an azole-resistant C. albicans isolate not overexpressing CDR1, the gene for another efflux pump named BEN(r) was massively overexpressed. This gene was cloned from C. albicans for conferring benomyl resistance in Saccharomyces cerevisiae. Therefore, at least the overexpression or the deregulation of these two genes potentially mediates resistance to azoles in C. albicans,ls clinical isolates from AIDS patients with oropharyngeal candidiasis. Involvement of ABC transporters in azole resistance was further evidenced with S. cerevisiae mutants lacking specific multidrug transporters which were rendered hypersnsceptible to azole derivatives including fluconazole, itraconazole, and ketoconazole.