School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand.
Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand.
Int J Pharm. 2021 Jun 1;602:120659. doi: 10.1016/j.ijpharm.2021.120659. Epub 2021 Apr 30.
Chemoresistance is a major factor driving cancer recurrence. This study investigated the potential of zebularine, a dual cytidine deaminase (CDA)/epigenetic inhibitor, to circumvent gemcitabine-resistance in pancreatic cancer using a nanomedicine co-delivery approach. The mRNA expression of key metabolic enzymes, including CDA for gemcitabine deactivation in a gemcitabine-resistant cell line Gr2000 and its parental MIA PaCa-2 was compared using quantitative reverse transcription polymerase chain reaction. A highly gemcitabine-resistant population (HRP) in Gr2000 were characterised for their growth pattern, β-galactosidase activity (a hallmark of senescence) and chemosensitivity to zebularine after isolation. The CDA inhibition effects of zebularine on the intracellular gemcitabine accumulation and pharmacokinetics in rats when co-delivered with pH-sensitive liposomes (pSL) were investigated. Gr2000 had a 3-time upregulated mRNA expression and enzyme activity for CDA. The HRP (28% of bulk Gr2000) were predominately senescent cells which re-proliferated following a growth arrest for a week. Zebularine suppressed the regrowth of senescent cells, meanwhile enhanced cellular gemcitabine concentration by 2-fold. When co-delivered with pSL, zebularine increased cellular gemcitabine concentration by 4-fold, and extended the half-life of gemcitabine in plasma by 22-fold in rats. In conclusion, multiple mechanisms including therapy-induced senescence were identified with gemcitabine-resistance. Co-delivery of zebularine using liposomes could provide multifaceted benefits in gemcitabine therapy for pancreatic cancer treatment.
化学耐药性是导致癌症复发的主要因素。本研究采用纳米医学共递药方法，研究了双胞嘧啶脱氨酶（CDA）/表观遗传抑制剂 zebularine 规避吉西他滨耐药性的潜力。采用定量逆转录聚合酶链反应比较了吉西他滨失活的关键代谢酶 CDA 在吉西他滨耐药细胞系 Gr2000 及其亲本 MIA PaCa-2 中的 mRNA 表达。对 Gr2000 中的高度吉西他滨耐药群体（HRP）进行了特征分析，包括其生长模式、β-半乳糖苷酶活性（衰老的标志）以及分离后对 zebularine 的化学敏感性。研究了 zebularine 与 pH 敏感脂质体（pSL）共递药时对细胞内吉西他滨积累和大鼠药代动力学的 CDA 抑制作用。Gr2000 的 CDA mRNA 表达和酶活性上调了 3 倍。HRP（Gr2000 的 28%）主要是衰老细胞，在生长停滞一周后重新增殖。Zebularine 抑制衰老细胞的再增殖，同时将细胞内吉西他滨浓度提高 2 倍。与 pSL 共递药时，zebularine 将细胞内吉西他滨浓度提高 4 倍，并将吉西他滨在大鼠血浆中的半衰期延长 22 倍。总之，与吉西他滨耐药性相关的多种机制包括治疗诱导的衰老。使用脂质体共递药 zebularine 可以为胰腺癌的吉西他滨治疗提供多方面的益处。
