ABCB1，又名MDR1，是一种编码P-糖蛋白（P-gp）的基因，它是一种与膜相关的ATP依赖性转运蛋白。P-gp在许多健康组织中广泛表达，包括胃肠道、肝脏、肾脏和血脑屏障。P-gp的功能是将外源性化合物（如毒素和药物）从细胞中排出。P-gp在卵巢、乳腺和肺等多种癌症类型中也常见上调。ABCB1的过度表达与这些癌症的化疗耐药性发展相关。在大量药物敏感性和耐药性癌细胞系的体外实验中，已经证明在使用阿霉素、顺铂和紫杉醇等化疗药物时，ABCB1会上调表达。这种上调部分是由多种遗传和表观遗传机制引起的，其中包括单核苷酸变异，可增强P-gp三磷酸腺苷酶活性，而不增加ABCB1的RNA和蛋白水平。在本综述中，我们总结了目前对多种癌症化疗耐药性环境中ABCB1上调和P-gp增强ATP酶活性的遗传和表观遗传机制的了解。

ABCB1, also known as MDR1, is a gene that encodes P-glycoprotein (P-gp), a membrane-associated ATP-dependent transporter. P-gp is widely expressed in many healthy tissues-in the gastrointestinal tract, liver, kidney, and at the blood-brain barrier. P-gp works to pump xenobiotics such as toxins and drugs out of cells. P-gp is also commonly upregulated across multiple cancer types such as ovarian, breast, and lung. Overexpression of ABCB1 has been linked to the development of chemotherapy resistance across these cancers. In vitro work across a wide range of drug-sensitive and -resistant cancer cell lines has shown that upon treatment with chemotherapeutic agents such as doxorubicin, cisplatin, and paclitaxel, ABCB1 is upregulated. This upregulation is caused in part by a variety of genetic and epigenetic mechanisms. This includes single-nucleotide variants that lead to enhanced P-gp ATPase activity without increasing ABCB1 RNA and protein levels. In this review, we summarize current knowledge of genetic and epigenetic mechanisms leading to ABCB1 upregulation and P-gp-enhanced ATPase activity in the setting of chemotherapy resistance across a variety of cancers.