Pregnane X receptor (PXR, NR1I2) is a member of the ligand-activated nuclear receptor superfamily. This receptor is promiscuous in its activation profile and is responsive to a broad array of both endobiotic and xenobiotic ligands. PXR is involved in pivotal cellular detoxification processes to include the regulation of genes that encode key drug-metabolizing cytochrome-P450 enzymes, oxidative stress response, as well as enzymes that drive steroid and bile acid metabolism. While PXR clearly has important regulatory roles in the liver and gastrointestinal tract, this nuclear receptor also has biological functions in breast tissue. In this review, we highlight current knowledge of PXR’s role in mammary tumor carcinogenesis. The elevated level of PXR expression in cancerous breast tissue suggests a likely interface between aberrant cell division and xeno-protection in cancer cells. Moreover, PXR itself exerts positive effect on the cell cycle, thereby predisposing tumor cells to unchecked proliferation. Activation of PXR also plays a key role in regulating apoptosis, as well as in acquired resistance to chemotherapeutic agents. The repressive role of PXR in regulating inflammatory mediators along with the existence of genetic polymorphisms within the sequence of the PXR gene may predispose individuals to developing breast cancer. Further investigations into the role that PXR plays in driving tumorigenesis are needed.

中文翻译：

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孕烷X受体与乳腺癌的生长和进展之间的关联。

孕烷X受体（PXR，NR1I2）是配体激活的核受体超家族的成员。该受体的活化特性是混杂的，并且对多种内生和异源配体都起反应。PXR参与关键的细胞排毒过程，包括调节编码关键药物代谢细胞色素P450酶，氧化应激反应以及驱动类固醇和胆汁酸代谢的酶的基因。虽然PXR在肝脏和胃肠道中显然具有重要的调节作用，但这种核受体在乳腺组织中也具有生物学功能。在这篇综述中，我们重点介绍了PXR在乳腺肿瘤致癌作用中的最新知识。癌性乳腺组织中PXR表达水平升高表明癌细胞中异常细胞分裂与异种保护之间可能存在界面。此外，PXR本身对细胞周期产生积极影响，从而使肿瘤细胞易于抑制增殖。PXR的激活在调节细胞凋亡以及对化学治疗剂的获得性耐药中也起着关键作用。PXR在调节炎症介质中的抑制作用以及PXR基因序列中遗传多态性的存在可能使个体容易患上乳腺癌。需要进一步研究PXR在驱动肿瘤发生中的作用。从而使肿瘤细胞易于抑制增殖。PXR的激活在调节细胞凋亡以及对化学治疗剂的获得性耐药中也起着关键作用。PXR在调节炎症介质中的抑制作用以及PXR基因序列中遗传多态性的存在可能使个体容易患上乳腺癌。需要进一步研究PXR在驱动肿瘤发生中的作用。从而使肿瘤细胞易于抑制增殖。PXR的激活在调节细胞凋亡以及对化学治疗剂的获得性耐药中也起着关键作用。PXR在调节炎症介质中的抑制作用以及PXR基因序列中遗传多态性的存在可能使个体容易患上乳腺癌。需要进一步研究PXR在驱动肿瘤发生中的作用。